5th Meet
Posted by: smithj
5th Meet - 12/07/2004 15:51
Guys,
I have just got back, thanks for a great time at the meet.
We had a play with the new build while waiting for the ferry, had to buy a mic in Amersfoort supermarket (ever tried asking for a mic when you don't know the dutch word!!)
Thanks to the build brothers for the build. I can at least say David Bowie and it works, took a while for me to work out the new menu's.
Once again thanks for a great time.
Cheers
Jason
PS: Patrick, it was my idea about where to put the usb socket!!
Posted by: tonyc
Re: 5th Meet - 12/07/2004 16:03
Quote:
I can at least say David Bowie and it works
The sound you're hearing is the sound of everyone who wasn't at the meet drooling on their keyboards.
Glad someone spilled the beans!
Posted by: pgrzelak
Re: 5th Meet - 12/07/2004 16:06
Mic??? As in "microphone"?!?!?! As in "a use for the mic in jack"?!??!?!
Posted by: genixia
Re: 5th Meet - 12/07/2004 16:13
It can't be...
Surely not...
No, I can't believe it...
Really?....
<pinches self>
Is this _really_ the long awaited VR feature?
Posted by: mtempsch
Re: 5th Meet - 12/07/2004 16:15
Quote:
Mic??? As in "microphone"?!?!?! As in "a use for the mic in jack"?!??!?!
Yup. Hope you haven't hijacked the mic wires for other uses...
But I think tonyc got the wrong idea of usage... 
A comment from one of the build brothers about shuffle applies...
At the meet the reaction was pretty much 
Posted by: mcomb
Re: 5th Meet - 12/07/2004 16:23
Quote:
Is this _really_ the long awaited VR feature?
<does a little happy dance>
Oh boy, oh boy, oh boy. Gimme, gimme, gimme
-Mike
Posted by: loren
Re: 5th Meet - 12/07/2004 16:31
Wow. That one post instantly made me forget about getting an iPod/Alpine link box. I'm back in full bore if this works!
Hrm... i wonder if i can use the same mic my wired bluetooth car kit uses...
Oh man oh man oh man....
Posted by: g_attrill
Re: 5th Meet - 12/07/2004 16:32
<swoons>
Posted by: peter
Re: 5th Meet - 12/07/2004 16:43
Quote:
<swoons>
Pack it in, you lot! There is no VR in those releases. This would be a different use for the microphone input.
Peter
Posted by: genixia
Re: 5th Meet - 12/07/2004 16:46
Hmm. Auto EQ based upon ordered sound file tracks?
Posted by: peter
Re: 5th Meet - 12/07/2004 16:49
Quote:
Hmm. Auto EQ based upon ordered sound file tracks?
Now wouldn't that be a nice feature? 
Peter
Posted by: schofiel
Re: 5th Meet - 12/07/2004 16:49
No, but it IS the long-discussed and awaited
(Censored) which - by the way - works pretty damn good, I have to say. Wonderful! The car sounds better already....
Posted by: pgrzelak
Re: 5th Meet - 12/07/2004 16:53
Hmmm... If the car sounds better, if must be something to configure audio. Perhaps an automatic EQ configuration system or dynamic volume control???
Posted by: loren
Re: 5th Meet - 12/07/2004 16:55
awwwww... no VR. =[ I got all worked up too. heheh.
Posted by: mcomb
Re: 5th Meet - 12/07/2004 16:55
Quote:
Now wouldn't that be a nice feature?
<shuffles feet and mumbles quietly>
Well, I guess that is pretty good too.
Its actually a much more useful feature I would imagine, but it doesn't quite have the same geewiz factor.
-Mike
Posted by: Phoenix42
Re: 5th Meet - 12/07/2004 16:56
volume control?
the more background noise the louder it gets?
Posted by: loren
Re: 5th Meet - 12/07/2004 16:57
Quote:
I can at least say David Bowie and it works, took a while for me to work out the new menu's.
?? So what does that mean exactly? *confused*
Posted by: mtempsch
Re: 5th Meet - 12/07/2004 17:02
Probably playing around with it w/o speakers, providing "David Bowie", spoken, as input to the mic, instead of the expected pink noise...
It behaved funnily at the demo, partly because shuffle and partly because it heard our clapping and cheering.
Posted by: pgrzelak
Re: 5th Meet - 12/07/2004 17:06
Hmmm... This implies something dynamic! Dynamic volume adjustment or EQ... Hmmm... Which could it be... Or, as was stated above, not quite VR but an audio match to perform specific actions on the player. Also intensely cool.
Question: why would this remain top secret / censored after the meet??? I know that the build is limited access, but surely the enhancements would be public... Right???
Posted by: genixia
Re: 5th Meet - 12/07/2004 17:09
So how'd'ya get over the sampling rate issue?
Posted by: peter
Re: 5th Meet - 12/07/2004 17:10
Quote:
It behaved funnily at the demo, partly because shuffle and partly because it heard our clapping and cheering.
The shuffle didn't stop it doing all the right things, just not necessarily in the right order. The clapping, cheering, cries of "Bravo", wolf-whistles, crowd-surfing, throwing of knickers etc. did skew the final part of the demo, but frankly, given the limitations of the sound system it was driving, that skewing provided a far more compelling demonstration of the principles than a perfectly clean demo would have done.
Peter
Posted by: pgrzelak
Re: 5th Meet - 12/07/2004 17:12
Instant drool!!!
If I read that right, this is an automatic EQ configuration system! RTA?!?!? SWEET!
So, what kind of microphone should I immediately go out and buy?
Posted by: peter
Re: 5th Meet - 12/07/2004 17:14
Quote:
Question: why would this remain top secret / censored after the meet??? I know that the build is limited access, but surely the enhancements would be public... Right???
I think the Amersfoortians are just collectively enjoying teasing the non-Amersfoortians. There's no official secrecy or censorship of that information -- in fact, the release notes all recommend the BBS as a good place to discuss the new features.
And just think how many days earlier you'd find this stuff out if you came to the next Empeg meet!
Peter
Posted by: genixia
Re: 5th Meet - 12/07/2004 17:16
Quote:
And just think how many days earlier you'd find this stuff out if you came to the next Empeg meet!
Hopefully not many. 
Posted by: peter
Re: 5th Meet - 12/07/2004 17:18
Quote:
So how'd'ya get over the sampling rate issue?
The sample rate is what, 29KHz or something? That gives us everything up to 14.5KHz in frequency, and above there we don't care. Very high frequencies are rarely the issue in this problem space.
Edit: I will just add that I only have a layman's knowledge of this particular feature -- I knew what John had done but hadn't even seen it in operation before Amersfoort. Really he should be answering all these questions, but I don't think he's on the board right now.
Peter
Posted by: mtempsch
Re: 5th Meet - 12/07/2004 17:18
Quote:
So, what kind of microphone should I immediately go out and buy?
Development was made with a "Ultra-mini electret insert" from Maplins (part no QY62S)
It's only reasonably flat between 50 and 13kHz, and they don't currently have the exact curve, but working on it -- if there's someone out there with a good reference mic and measuring gear, they could reportedly help out...
Posted by: tfabris
Re: 5th Meet - 12/07/2004 17:28
Quote:
The sample rate is what, 29KHz or something? That gives us everything up to 14.5KHz in frequency, and above there we don't care. Very high frequencies are rarely the issue in this problem space.
We were told a long time ago that the limit was something more like 11khz...
Posted by: peter
Re: 5th Meet - 12/07/2004 17:43
Quote:
We were told a long time ago that the limit was something more like 11khz...
That's a much rounder number and so probably right (though maybe it does 22KHz normally and 29KHz in some kind of Super Pursuit Mode if you program all the right bits). But even if it's 11KHz, the comment still stands: all the action here is in the bass.
Peter
Posted by: tfabris
Re: 5th Meet - 12/07/2004 17:49
Agreed.
Quote:
Guys,
I have just got back, thanks for a great time at the meet.
We had a play with the new build while waiting for the ferry, had to buy a mic in Amersfoort supermarket (ever tried asking for a mic when you don't know the dutch word!!)
Thanks to the build brothers for the build. I can at least say David Bowie and it works, took a while for me to work out the new menu's.
Once thanks for a great time.
Cheers
Jason
PS: Patrick, it was my idea about where to put the usb socket!!
Is it April Fool's Day somewhere?
Posted by: AndrewT
Re: 5th Meet - 12/07/2004 22:19
Quote:
There's no official secrecy or censorship of that information -- in fact, the release notes all recommend the BBS as a good place to discuss the new features.
So, would the BBS be a good place to post the release notes? Hint, hint! Is that allowed? 
(Sorry, I can't hide my impatience after the serious appetite whetting that's gone on above!)
Posted by: weasel
Re: 5th Meet - 12/07/2004 22:43
i have the VR working ... how cool!
Posted by: mlord
Re: 5th Meet - 13/07/2004 00:07
I'm now back at home in Canada, and have a suitable mic with me here. All ya have to do is drop by to try it out. I also have one of the disc's here..
Cheers
Posted by: JonnyGee
Re: 5th Meet - 13/07/2004 08:22
Quote:
So how'd'ya get over the sampling rate issue?
I don't. But then I can't hear over about 14K so from a purely personal POV I don't care
In theory, since the (censored) is only measuring the RMS (censored), some sort of electronic hack could be performed eg calculating the RMS electronically and regenerating a signal of the correct level (it could just be a sinewave at a fixed frequency).
Maybe we should be collecting together this info somewhere for future reference - that will be easier if/when the veil of secrecy is lifted.
Posted by: JonnyGee
Re: 5th Meet - 13/07/2004 08:26
Quote:
Quote:
It behaved funnily at the demo, partly because shuffle and partly because it heard our clapping and cheering.
The shuffle didn't stop it doing all the right things, just not necessarily in the right order. The clapping, cheering, cries of "Bravo", wolf-whistles, crowd-surfing, throwing of knickers etc. did skew the final part of the demo, but frankly, given the limitations of the sound system it was driving, that skewing provided a far more compelling demonstration of the principles than a perfectly clean demo would have done.
Peter
In fact it was unlikely to work properly in the demo even if I'd turned off shuffle - the mic was far too close to the speaker, which was far too quiet and there was way too much background noise.
Cheers, John
Posted by: JonnyGee
Re: 5th Meet - 13/07/2004 08:38
Quote:
That's a much rounder number and so probably right (though maybe it does 22KHz normally and 29KHz in some kind of Super Pursuit Mode if you program all the right bits). But even if it's 11KHz, the comment still stands: all the action here is in the bass.
The input can be set to 11.025KHz, 22.05KHz or 29.4KHz. The 11KHz limit mentioned corresponds to a 22.05KHz sample rate which is probably the rate used when sampling aux or tuner for visuals generation (I think Toby wanted to use one of the "standard" rates for his algorithms).
I just maxed out to 29.4KHz for (censored) because the RMS algorithm doesn't care about the sample rate.
It might be a little strong to say that high frequencies are entirely irrelevent. There certainly seem to be fewer peaks and dips up there than in the bass range in real car systems, but you never know when someone's tweeters might have a horrible peak at say 17KHz - unpleasent for anyone who can hear that high.
Cheers, John
Posted by: genixia
Re: 5th Meet - 13/07/2004 13:58
Ah, I didn't know about the 29.4KHz rate. I don't believe it was mentioned in the old kernels and I've never read the full specs for the CS4231A. I'm guessing that makes a big difference. There's a lot of audible information between 11.05KHz and 14.7KHz.
If you're looking for a way to regenerate sine waves of a known frequency then I may be able to help. About a year ago I created a hijack patch to use the DSP's tone generators to produce any tone on demand. Unfortunately the patch never made it into the hijack tree, and since then some of the existing code that the patch relied on has been removed (I used the calculator UI for numerical entry), so it's not a completely trivial merge. The patch included ioctls and also included a fixed point library for the kernel which could be useful for doing other DSP related coding, athough I guess you've got such a library in the player codebase anyway.
Anyway, if you are interested then once I get the new alpha then I can create a patch against it.
Posted by: FireFox31
Re: 5th Meet - 14/07/2004 00:32
Quote:
Development was made with a "Ultra-mini electret insert" from Maplins (part no QY62S)
Aw shoot, maybe I'm too electronically disinclined for this mic. Does it require soldering to get a cable and a jack on there? And... hm, I forget how the mic in line on the sled works. Is it just a bare mono line, or a single phono?
In other words, will it require me to learn how to solder and then tear up my install to use the cool newness of V3a8?
Posted by: Daria
Re: 5th Meet - 14/07/2004 02:03
Can i drop by and try out the disc?
Posted by: mtempsch
Re: 5th Meet - 14/07/2004 02:37
Quote:
I forget how the mic in line on the sled works. Is it just a bare mono line, or a single phono?
It's a 3.5mm mono jack - it looks like the microphone is "bare", ie you'd have to solder on a wire (and the wire to a 3.5 mm mono plug at the other end)
Quote:
In other words, will it require me to learn how to solder and then tear up my install to use the cool newness of V3a8?
Solder: either you or someone else to do it for you. It's just 4 solder points in all.
Tear up: depends on where your mic input jack is currently stashed, if you can get your fingers on it or not, and if you can feed the wire from the mic from somewhere to the rear/top of the sled and connect jack and plug together w/o having to remove the sled.
Posted by: mlord
Re: 5th Meet - 14/07/2004 03:17
By all means, feel free!
Posted by: Daria
Re: 5th Meet - 14/07/2004 03:52
Hm. Wonder how far of a drive it is.
Posted by: mlord
Re: 5th Meet - 14/07/2004 09:02
Mmmm.. about 7-8 hours I should imagine -- it takes me about 6.5 hours to get here from the Mohonk Preserve (aka "gunks"), which is 70miles this side of NYC.
Cheers
Posted by: FireFox31
Re: 5th Meet - 14/07/2004 23:29
Thanks Mike.
Hm, I wonder if I should buy like 10 of these mic's (no, not possessive, just using an apostrophie to pluralize an abbreviated word). Since I'd have to ship from the UK, I might as well make it worth the cost.
.... scratch that. A quick attempt to register with Maplins shows that they don't ship to the US. Hm, ok. No "Build Brothers Certified" mic for me.
Posted by: Phoenix42
Re: 5th Meet - 14/07/2004 23:32
I'm sure some one here will do the honours of mailing over a bundle of them to someone for forward to others.
Posted by: genixia
Re: 5th Meet - 15/07/2004 02:23
I'm sure that we could find a local equivalent.
Posted by: RobotCaleb
Re: 5th Meet - 15/07/2004 03:32
apostrophe*
Posted by: jarob10
Re: 5th Meet - 15/07/2004 04:18
Quote:
I'm sure some one here will do the honours of mailing over a bundle of them to someone for forward to others
I will gladly help out.
Posted by: JonnyGee
Re: 5th Meet - 15/07/2004 11:46
Don't worry too much about which mic element to use - I'll try and calibrate mine this weekend but I expect to find it's flatish from about 100Hz to 10KHz and just droops a bit outside this range. Pretty much any small condenser element should behave similarly.
Maybe someone over there in the US could choose an easily obtainable element and calibrate it (or you could post a sample to me and I'll do it, but my setup isn't exactly professional
).
One with a published curve would be better of course.
Cheers, John
Posted by: robricc
Re: 5th Meet - 15/07/2004 12:02
Does
this work for you? I can get this and send it over asap.
Posted by: genixia
Re: 5th Meet - 15/07/2004 12:56
That mic. is unidirectional, not omnidirectional.
A more likely RatShack candidate is
this one.
If that's not suitable then digikey have a long list of mic's. I'd be willing to do a bulk order.
Posted by: mlord
Re: 5th Meet - 15/07/2004 13:08
It has to be a condensing microphone -- dunno if that one is or not.
On a related note -- running AutoEQ with NO MICROPHONE attached currently does not do what one might expect of it.. needs some fine tuning, I guess.
Cheers
Posted by: pgrzelak
Re: 5th Meet - 15/07/2004 13:11
Wow... And I was looking in the entirely
opposite direction when it came to a microphone...
Posted by: genixia
Re: 5th Meet - 15/07/2004 15:05
Hmm. I thought that all electret microphones were condensers...
What we do need to know is which parameters are important for this use. We know that we don't need a response beyond 15KHz as the sampling rate is 29.4KHz, although a microphone with an extended range may be flatter for longer. What what about the low end? The Maplin model goes down to 50Hz. We know the DSP is capable of EQing lower than that (17Hz IIRC), although it was limited in software (to 50HZ IIRC). How low does the autoEQ measure?
Is the sensitivity important? Presumably, because the software doesn't know anything about amp gains, it cannot make any assumptions about the audible volume vs the empeg's logical volume. As such, I would also presume that the software has to be fairly smart and would level the frequency response to the average volume, without caring what that volume actually was, hence making the sensitivity of the microphone non-critical.
Voltage and impedance requirements? The Maplin one is 4.5V (optimum) and 1Kohm. How much variance is acceptable?
Posted by: JonnyGee
Re: 5th Meet - 15/07/2004 16:27
Hi
Both Radio Shack microphones are condensor types and will be compatible with the car player's input (I think the phantom power supply is about 3V in a car player). There's a data sheet for the KUC1515-01-0850 at
http://support.radioshack.com/support_supplies/doc9/9798.htm which specifies a wide voltage range of 2-10Volts. From this, and thinking about how these mics work, I believe the exact voltage isn't critical in general.
We do however need to use an omnidirectional mic, since omni mics measure the pressure due to the sound not the air velocity (hence we get a true SPL).
I also prefer the KUC1515-01-0850 as a "standard" unit because it has wires on. Soldering onto those mics is a bit tedious for someone with "normal" soldering skills like me.
I love the Behringer ECM8000 measurement mic - in fact the idea of AutoEQ came from a rainy day in Somerset with Roger, John Ripley and me in Roger's car with my ECM800 and UltraCurve2496 basically trying to determine how Roger's EQ should be set for a flat response. Sadly the ECM8000 specifies 15-42 volts DC supply (typical for pro equipment). It might just work anyway at 3V, but I couldn't guarantee it would still be flat, making the excercise a bit pointless. Another option might be to pre-amp the mic properly and use that signal.
The frequency ranges specified for the microphones is likely to be a "reasonably flat in this range" type thing. We should be able to compensate as long as the microphone doesn't lose so much sensitivity out of range that its signal drops below the noise floor.
I just looked at the EQ code, and can't find a trace of the limits that I added based on some research by someone on this BBS into which low-frequency settings make the EQ go wrong. It's in there somewhere, I'm sure
. Basically it replaced the old 50Hz limit with a combination of limited boost/cut limits at frequencies below 50Hz.
AutoEQ bands are centred on:
- 25
- 40
- 63
- 100
- 160
- 320
- 800
- 2k
- 5k
- 12.5k
In the absence of calibration data you should only rely on the results for bands comfortably inside the mic's flat range. Other bands can be set to 0dB or set by ear.
Best microphone positioning is near your head, because that's where your ears are. You also need to keep background noise as quiet as possible (including handling noise). While AutoEQ is running, the level should be within the range of the cute little VU meter
and ideally >=10dB higher than the background noise level. AutoEQ won't do this for you, you have to do it yourself and that may take a few trial runs.
Cheers, John
Posted by: tfabris
Re: 5th Meet - 15/07/2004 16:32
Quote:
I just looked at the EQ code, and can't find a trace of the limits that I added based on some research by someone on this BBS into which low-frequency settings make the EQ go wrong. It's in there somewhere, I'm sure
That was me, and the reason you can't find it is because that's one of the things that went into place after the codebase tree split. It's in the 2.0 tree and not the 3.0 tree.
Please don't put the limits back into the 3.0 tree. I did the research hoping to find out why I was getting strange distortions and I thought it might be an easy bugfix. I didn't want to be artificially limited in the EQ ranges.
Posted by: pgrzelak
Re: 5th Meet - 15/07/2004 16:48
I love the Behringer ECM8000 measurement mic - in fact the idea of AutoEQ came from a rainy day in Somerset with Roger, John Ripley and me in Roger's car with my ECM800 and UltraCurve2496 basically trying to determine how Roger's EQ should be set for a flat response. Sadly the ECM8000 specifies 15-42 volts DC supply (typical for pro equipment).
I can think of no better recommendation. And, because I have a 9V battery operated phantom power supply (as linked to in the other thread), I think this will be a good choice. Thanks!
Posted by: FireFox31
Re: 5th Meet - 16/07/2004 00:39
Quote:
apostrophe*
Aw, man. What have I ever done to you? 
And where were you for my past nearly 2 years of horribly spelled posts?
Posted by: Miltoid
Re: 5th Meet - 16/07/2004 01:03
Quote:
Please don't put the limits back into the 3.0 tree... I didn't want to be artificially limited in the EQ ranges.
I'll second that! I've been afraid to ask if the 50Hz limit from 2.0final had migrated into 3, since I've been too chicken to subject "Tux the tunebox" to any alpha builds.
Posted by: tfabris
Re: 5th Meet - 23/07/2004 16:41
Quote:
I also prefer the KUC1515-01-0850 as a "standard" unit because it has wires on.
Mister Graley, sir, I have a question.
In preparation for the autoEQ feature, I just bought a Radio Shack 270-092, which I think (from what I can gather from this thread) is the unit described in that datasheet you linked, Model # KUC1515-01-0850.
Depending on where you look, the last digits of the model number are either 092 or 0092, but I think those two are synonymous in the ratshack parts system. Anyway...
The part I purchased doesn't look like the photo at the radio shack web site linked above. It has three wires coming off of it when I expected two. There is a red and a white wire, as well as a sheath to the white wire. Photo attached...
I thought that the mic connector on the empeg was only two conductors, i.e., mono 1/8". I thought that three conductors meant a balanced connection. So here are my questions:
- Will this mic work?
- I've purchased a mono 1/8" male jack to solder to this microphone so that I can plug it into the empeg's mic connector. If this mic will work, then which wires do I solder to the tip and sleeve of the mono 1/8" jack?
Posted by: wfaulk
Re: 5th Meet - 23/07/2004 16:52
The
mechanical drawing lists the red wire as the "power supply wire" and the gray wire(s?) as the "output wire". That doesn't really help me, but maybe it'll mean something to someone else.
Posted by: tfabris
Re: 5th Meet - 24/07/2004 19:25
Here is a clearer schematic, from the back of the box. From the looks of it, this microphone needs to be powered. Not sure.
Anyone?
Under the white wire it says "Optional coupling capacitor". Think that means the white is optional? The others it says exactly what they are, Output and Ground. I should really take and electronics class sometime....
Posted by: tfabris
Re: 5th Meet - 24/07/2004 19:35
You're reading it wrong.
Red= V+
White = Output
Shield = Gnd
The "optional coupling capacitor" refers to the capacitor symbol drawn on the white (output) wire.
Posted by: andym
Re: 5th Meet - 24/07/2004 19:50
That sucker needs volts.
The diagram shows a little triangle, that's an amp hence it needs power. I'm sure you could power it off a battery. However it's probably easier to just get one that doesn't need power.
Posted by: tfabris
Re: 5th Meet - 24/07/2004 20:01
Actually, I happened to have a little two-double-A battery holder sitting here with a couple of wires hanging off of it. I'm trying that next.
Doh!
I see now what you mean... Have to look closer next time!
Posted by: tfabris
Re: 5th Meet - 24/07/2004 20:26
Quote:
However it's probably easier to just get one that doesn't need power.
Anyone have any idea which radio shack part number would be the correct one, then?
Adding 3v power to this one works, however its output level is quite low.
Posted by: gbeer
Re: 5th Meet - 24/07/2004 20:42
It would be low on only 3v. Try patching in a 3rd battery to bring it up to 4.5v.
Posted by: tfabris
Re: 5th Meet - 24/07/2004 21:14
Quote:
It would be low on only 3v. Try patching in a 3rd battery to bring it up to 4.5v.
I just tried 9 volts on it (was easier than patching in a 3rd AA batery), and got the exact same output level. Recorded myself into Sound Recorder saying the same thing at the same volume level with the same distance from the mic, once with 3v power and once with 9v power. Same level of output when the two wav files were played back. They were both very quiet (needed to turn my speakers up all the way to hear it) but very clean.
Posted by: dizar
Re: 5th Meet - 25/07/2004 01:43
First of all, a liitle 101 on microphones: there are 2 kinds:
Dynamic - They are somewhat the opposite of speakers (sound waves move a coil in a magnet), are extremely directional (they have a "cardioid" response in horizontal level) and are typically used in drum sets and some high end models as cheap alternatives in various applications where good performance is required (community radio would be a good example). They don't need to be supplied with power and they don't come in small sizes.
Condenser - They are in essence a capacitor, as the diaphragm is placed over a back plate and as the diaphragm vibrates to sound waves the capacitance between the two changes. For them to work the diaphragm must be polarized, hence the need for power. Condenser mics are omni-directional (when you see a mic on a round table or the mics worn on clothes in TV you can safely bet it's a condenser one although there are exceptions), have generally better frequency response than dynamic ones but are susceptible to room volume and ambient noises.
Now to the point:
The schematic you have is obviously wrong since the way it is drawn it clearly indicates a short between power and ground (1 and 3). I think the black dot was intended to go after the triangle. That also explains the "optional coupling capacitor" that is there to cut off DC and let just the signal go through (and I think that may be why you are having poor performance with yours).
This is all more thoroughly explained
here from where I'm copying the following:
Code:
vcc
O
|
/
\
/
\ EQUAL TO REQUIRED IMPEDANCE
/ EX.= 1000 Ohm
\
|
| CAPACITOR MOST ANY VALUE 10uF 16v
|---| | + | /
| |---0----| |------- AUDIO OUT
| | | \
| |----O--------------
|---| |
|
-----
---
-
Now what made me wonder is John Graley's post where he claims "Both Radio Shack microphones are condensor types and will be compatible with the car player's input (I think the phantom power supply is about 3V in a car player)."
Now I did measure with my multimeter and tada, there IS an aprox. 4.5V power supply on the mic connector, so I guess you can just plug wires 2 on the tip and 3 on the ring of the empeg connector and it should work ( i.e. the coupling capacitor should be inside the empeg somewhere and the mic will "feed" by power provided from the unit). Or perhaps you might need to connect 1 and 2 together on the tip if the mic refuses to work out of the white wire.
Sorry for the length and hope this helps.
Dimitris Zarafonitis.
Posted by: Shonky
Re: 5th Meet - 25/07/2004 04:25
Quote:
The schematic you have is obviously wrong since the way it is drawn it clearly indicates a short between power and ground (1 and 3). I think the black dot was intended to go after the triangle. That also explains the "optional coupling capacitor" that is there to cut off DC and let just the signal go through (and I think that may be why you are having poor performance with yours).
Actually that schematic is correct. It does not show a short to ground at all. The triangle is a preamp (op-amp) inside the mic somewhere. That's pretty standard having the power connections come in either side of the op-amp diagram.
Thus the 3 connections to the mic.
Posted by: dizar
Re: 5th Meet - 25/07/2004 10:57
Quote:
The triangle is a preamp (op-amp) inside the mic somewhere.
So that's what it (clearly ) is
Andy M mentioned it too, but I didn't notice. As I glanced at the schematic it seemed like line 1 was going under the op-amp not like a component with 4 connections. My bad.
So I guess this means for Tony that 1+2 go into the tip of the connector and 3 on the ring. This should work since emped does have phantom power so it must have the coupling capacitor in it's circuit internaly or else it would feed DC to it's mic stage.
The (oversimplified) schematic should look like this:
Code:
empeg unit
------------------------
| |
| |
| | vcc |
| / |
| \ |
| / |
--------- | \ |
| | | | |
|---| -------- | | | | / |
| |---|OP-AMP|---o-------0---| |-- |
| | -------- | | \ AUDIO |
| | | | OUT |
| |------O--------------------o---- |
|---| | | |
| --- |
| - |
------------------------
Cheers.
Edit: Allthough now that cofee has kicked in I can't help but think that a capacitor is needed between the op-amp output and the point where red and white wires get joined to cut off DC coming onto the op-amp's output. Hence the reference to the optional coupling capacitor on the mic's schematics.
Which should be lesson enough to not post a) before bed and b) after just having waked up
Code:
empeg unit
------------------------
| |
| |
| | vcc |
| / |
| \ |
| / |
------------ | \ |
| | | | |
|---| -------- \ | | | | | / |
| |---|OP-AMP|--| |-o-----0---| |-- |
| | -------- / | | | \ AUDIO |
| | | | OUT |
| |------O---------------------o---- |
|---| | | |
| --- |
| - |
------------------------
Posted by: tfabris
Re: 5th Meet - 25/07/2004 14:16
This is very good information. Now the only real remaining question is whether I need the capactior or not.
Question: The capacitor, doesn't it change the frequency response of the microphone?
Posted by: tfabris
Re: 5th Meet - 25/07/2004 14:29
Hm, I've got a box of 0.1uF capactiors, would that work?
... And I'm not clear on which direction (plus or minus) the leads are supposed to go in the schematic. For that matter, I'm not sure which leads are plus or minus on these capactiors. They're little ceramic jobbies, ratshack part number 272-109a. It's not like an LED where one lead is longer than the other, they're both the same length...
Posted by: mtempsch
Re: 5th Meet - 25/07/2004 14:43
Quote:
little ceramic jobbies
Most likely non-polarized...
Posted by: tfabris
Re: 5th Meet - 25/07/2004 15:04
Thanks. Okay, tried it with the 0.1uF capacitor in place trying to use phantom power on the signal line as drawn. Works, but is quieter than when I supply the voltage myself without the capacitor. Since I'm plugging into my SoundBlaster Live instead of the empeg, it's possible that the soundcard doesn't supply phantom power at all.
Still don't know whether this capacitor is changing the frequency response or not?
Posted by: dizar
Re: 5th Meet - 25/07/2004 16:22
Quote:
Thanks. Okay, tried it with the 0.1uF capacitor in place trying to use phantom power on the signal line as drawn. Works, but is quieter than when I supply the voltage myself without the capacitor. Since I'm plugging into my SoundBlaster Live instead of the empeg, it's possible that the soundcard doesn't supply phantom power at all.
Still don't know whether this capacitor is changing the frequency response or not?
Check here again about 1/4 down the page where it says "Soundcards and electret microphones". Check the whole section as it has many alternative wiring methods for soundcards. Apparently SB has a stereo plug that uses "Input Wiring: Audio on Tip, Ground on Sleeve, 5Volts DC Bias on Ring" as mentioned on the page.
In other words, if you use SB then you can connect ground/red/white to sleeve/ring/tip respectively and it will work without a capacitor (if you have a stereo jack, then it would be interesting to let us know the results this way). If you used a mono jack on the SB, then you're not feeding the mic any power. On the empeg just use a capacitor and a 2 conductor wire (coaxial preferable).
I don't think the capacitor will (significantly) alter the frequency responce of the microphone.
Cheers.
Posted by: tfabris
Re: 5th Meet - 25/07/2004 16:26
Thanks, makes sense.
Quote:
I don't think the capacitor will (significantly) alter the frequency responce of the microphone.
Since the purpose of auto-EQ is precise frequency adjustment, even small changes in the frequency response would be undesirable. Anyone know just how much the capacitor would change the frequency response if at all?
Posted by: andym
Re: 5th Meet - 25/07/2004 17:28
How will the empeg provide this power? Bearing in mind the jack is mono.
Posted by: tfabris
Re: 5th Meet - 25/07/2004 17:42
Quote:
How will the empeg provide this power? Bearing in mind the jack is mono.
On the signal line (tip of plug) as phantom power, just as drawn in the schematics above. Signal line does double duty: supplies power as well as sensing the signal.
Posted by: andym
Re: 5th Meet - 25/07/2004 18:04
Never heard of single ended phantom power. Then again I try not slum it in domestic audio.
Posted by: dizar
Re: 5th Meet - 25/07/2004 21:37
Tony,
Try the following 2 on your SB:
Code:
----------------------- TIP
|
|---| -------- \ |
| |---|OP-AMP|--| |------------- RING
| | -------- / |
| | |
| |------O---------------------- SLEEVE
|---|
| /
------------ ---| |-- TIP
| | | | \
|---| -------- \ | | |
| |---|OP-AMP|--| |-o---o------- RING
| | -------- / |
| | |
| |------O---------------------- SLEEVE
|---|
Schematic 1 is the ideal, while 2 is closer to what you'll get on the empeg. Try recording with the two configurations and see what goes on.
I would suggest recording the same parts of a track out of your stereo with the mic in the exact same position and the volume untouched. If you get significant difference try using capacitors nearer the 10uF value (or even bigger) of high-quality plastic film type. Also bear in mind the voltage of your capacitors (the 16V offered in the aforementioned page is OK for a theoretical maximux 10V voltage).
If I understand the theory in this correctly, the capacitors will not in any way alter the response FREQUENCY WISE since the signal is of alternating nature and measured in the range of a few hundred mVolts max. There is a chance though that you will get weak signal, that's why I'm suggesting experimenting a little with the capacitance and you can also try adding a resistor as in the following shematic to adjust to the input impedance that is 600 to 1500 Ohms in SB. I have a tie clip type condenser here that uses a 22uF after its 1.35 volts button battery and a 1000 Ohms resistor.
Code:
| /
---/\/\/\--- ---| |-- TIP
| | | | \
|---| -------- \ | | |
| |---|OP-AMP|--| |-o---o------- RING
| | -------- / |
| | |
| |------O---------------------- SLEEVE
|---|
Me has no idea what the input impedance is on the empeg, but I'm quessing roughly the same as the SB.
Cheers.
PS. OTOH, istead of going through all this trouble, you could just go and get yourself a 2 wire condenser
Posted by: tfabris
Re: 5th Meet - 25/07/2004 23:32
Quote:
istead of going through all this trouble, you could just go and get yourself a 2 wire condenser
See, that's the problem. I want to get the exact correct mic that can be used for the auto-EQ feature on the v3a8 player software. I came to this thread and was directed to that radio shack part number. So was that part number wrong?
If so, then what is the right part number?
Posted by: StigOE
Re: 5th Meet - 26/07/2004 05:54
I'm not sure if they'd work, but you can put them either way. They're not polarized. Just try and see if it works.
It's a long time since I last read about these microphones, but I seem to remember that you'd need to put a resistor between pin 1 and 2. A Google should turn up something about them...
Stig
Edit: Looks like I just replied to an earlier post.... Think I need to check my cache settings. Bummer...
Edit 2: I think a 0.1uF cap is too small. I know that an amplifier I built used a 2.2uF at the input. And yes, the cap will affect the frequency-curve. It will be a LF-filter, but I can't remember much of the theory. It's about 16 years since I learnt (and used) it...
Posted by: JonnyGee
Re: 5th Meet - 26/07/2004 15:19
Oooh dear it lookes like I've got a lot of catching up to do.
The AutoEQ is not optimised for any particular mic. It assumes the microphone has a flat frequency response. The better the mic you use, the better the AutoEQ will perform, but for thorectially perfect results, you would have to know the frequency response of your mic and correct for it afterwards (by simply adjusting the eq gains manually).
Now, my idea about nominating a particular model of microphone for a "standard" is simply that we can determine its frequency response and share that info between everyone who has the same mic. Rather like internet standards, consistency is more important than quality.
However, it turns out that radio shack were rude enough not to mention in their
datasheet that the KUC1515-01-0850 is a 3 lead model.
This makes it hard to connect to the player without additional components, and those component values will affect frequency repsonse... thereby undermining our attempts sharing a measured frequency response.
The question is, how many people have bought one? If lots of you guys have then we now need to invent a
recommended standard way of connecting the KUC1515-01-0850 to the car player otherwise I will
un-recommend the KUC1515-01-850 and pick something else with 2 leads to recommend instead.
I couldn't find a circuit on
http://www.hut.fi/Misc/Electronics/circuits/microphone_powering.html for connecting a mic such as KUC1515-01-850 to a car player. I would have thought, referring to
Tony's image that
- empeg ground to mic ground
- empeg signal to mic power (red) via 3.3K resistor
- empeg signal also to mic signal (white) via 4.7uF capacitor
might work from looking at the car player schematics (basically trying to seperate AC signal from DC power).
Cheers, John
Posted by: matthew_k
Re: 5th Meet - 26/07/2004 15:33
At a total of $4, I'm pretty sure most people would be willing to buy a seccond more appropriet one should they have already bought the radio shack one.
Matthew
Posted by: tfabris
Re: 5th Meet - 26/07/2004 15:59
Yes, I'd be happy to spend a few bucks on another mic, provided that I knew for sure it was going to work.
I stopped in Radio Shack today and found a 2 conductor Omnidirectional Condenser microphone for $1 less than the other one. Model number 270-090 (no docs on radioshack.com) The frequency response looks the same. From its wiring diagram it looks to do just like what we were saying before combining the power and output leads. It puts both power and output on the same lead, but wants a resistor later when it is split up(this would be inside the empeg?)
Differences from Tony's include:
Supply Voltage: 1.0 to 10VDC
Current Drain: 0.3mA (max)
Signal/noise: 60dB(min)
Sensitivity: -64 + or - 2dB
And now for the crappy pics! Sorry, no camera with macro capability.
Next to wiring diagram it says "Optional coupling capacitor (1-10 ufd)" and between the wires it says: "Resistor required (up to 1k)"
Posted by: JonnyGee
Re: 5th Meet - 27/07/2004 08:44
Looks hopeful. How about this time we try out the mic first and then standardise on it once we're sure it's suitable.
If others have the 3-wire mic and are impatiant to try out the feature, I suggest in the meantime using either batteries or my suggested circuit to run the mic and have a go... it will take a while to get used to the EQ. Remember to turn off shuffle, xfade etc and set EQ locks to independant.
Cheers, John
Posted by: tfabris
Re: 5th Meet - 27/07/2004 16:46
Quote:
If others have the 3-wire mic and are impatiant to try out the feature, I suggest in the meantime using either batteries or my suggested circuit to run the mic and have a go...
Tried it with the batteries and the gain level was too low for v3a8 to do proper compensation. The level meter only flicked a few pixels briefly on the lowest frequencies. This was with the volume cranked uncomfortably loud on the player.
Posted by: JonnyGee
Re: 5th Meet - 29/07/2004 13:07
It's possible that the mic is rolling off down at those frequencies. Were all the other bands looking OK for levels during the test? If so, then those other bands are probably EQ'd correctly.
Cheers, John
Posted by: tfabris
Re: 5th Meet - 29/07/2004 15:35
No, I'm talking about the animated "VU Meter" bar on the upper left of the screen. It blinks and shows the input level when the microphone gets input. For instance, if I tap the mic, I see it flash a level for a moment.
So I can tell when the mic is "hearing" something loud enough to register.
What I'm saying is that this particular mic is nowhere near sensitive enough to make any of the frequencies register at all, except the lowest subwoofer bass notes that make my car shake. Only those lowest car-shaking frequencies made that little level meter blink at all. The midrange and higher frequencies didn't even make it blip.
The mic just doesn't get "loud enough".
Posted by: matthew_k
Re: 5th Meet - 29/07/2004 17:33
Quote:
The mic just doesn't get "loud enough".
Should of got one that went up to 11, eh?
Matthew
Posted by: wfaulk
Re: 5th Meet - 29/07/2004 17:35
should've
Posted by: tfabris
Re: 5th Meet - 29/07/2004 19:02
Gotta fix your user title back to "Grammar Police" again.
Posted by: genixia
Re: 5th Meet - 13/08/2004 01:26
Ok, I picked up a RatShack 2 wire pcb-mount electret mike today,
270-090 for $2.59. The specs that their webpage link to do not match those given on the back of the package though. Package is;
V+: nominally 4.5V, 1V < V+ < 10V
ID: 0.3mA max.
SnR: 60dB min.
Sensitivity: -64 +/-2dB
Ro: 1kohm.
Frequency response graph is identical to that which Tony scanned earlier in the thread, flat from 30Hz to about 2.5kHz, 10dB/octave rise to 5kHz, 10dB/octave rolloff from 5KHz (ie 0dB at 10kHz).
I also picked up a cable. It turns out that RatShack sell one ideally suited to this task - 1/8" mono plug to tinned wire ends, 6' long, for $3.29. (42-2434)
I'll let you know how I get on with this when I get a chance to play with it.
Looks like the exact mic I have here as well. I haven't messed with mine yet so I can't wait to hear how yours turned out. I really need to go get more heat shrink as it's the only thing keeping me from finishing this.
I was planning on picking up these parts today. Have you had any luck with them?
I have about 4 or 5 local friends and family that have empegs (and for some reason never got involved on this BBS) and I'm going to setup my spare empeg with the AutoEQ alpha to bring to each of their cars. Granted, they'll have to pull their dash to gain access to the microphone input, but then we'll simply copy the EQ settings over to their players.
Is there a way to transfer only the EQ presets via ftp from one empeg to another?
Posted by: andym
Re: 5th Meet - 15/08/2004 13:17
Guys, I don't know if you've already tried Auto Eq, but I warn you that you might be disappointed. It's still in the early stages of development, and out of the half-a-dozen curves I've made with this feature, only 1 is listenable and my favorite setting is still the one made by using the flaps of skin either side of my head.
The best feature of alpha8 is the extended memory support.
Hm... I could have sworn a few people posted that they were getting great results with this. I think Mark Lord was one of them, I don't remember the others.
Posted by: andym
Re: 5th Meet - 15/08/2004 13:52
It seemed to work the first time I tried it in the house but once I got in the car there was clicking/popping/whining noises as the eq tried to adjust itself. This was after following all of JonnyG's instructions.
Posted by: schofiel
Re: 5th Meet - 15/08/2004 18:45
Then I would suggest that either your sled wiring is damaged for the mike (loose earthing crimp?) or that you have got the mike positioned pretty close to one channel of the amp output. Try checking them out.
Posted by: andym
Re: 5th Meet - 15/08/2004 19:06
I checked the sled before I installed the mic and everything was okay. The empeg behaves flawlessly in every other aspect so I doubt the amp wiring is at fault. The mic was held in the centre of the car. I have tested the mic with several other sources.
If I were to say anything was faulty then I think it's the DSP. As I mentioned in another thread, it never seems to play all the tones, there always one or two tones that you couldn't hear. Of course another run of the auto eq would result in another tone being inaudible. I very nearly damaged the speakers last time and was left with a high pitched whining noise that you could only get rid of by selecting another eq preset. I'm not really keen on trying it again just yet.
Has anyone sucessfully used AutoEq in a car? Because i'm unable to find any posts that say this.
Posted by: genixia
Re: 5th Meet - 15/08/2004 19:11
One thing to note - having shuffle mode activated can cause unpredictable results.
Posted by: andym
Re: 5th Meet - 15/08/2004 19:17
I think I said earlier on that i'd made sure all of that sort of stuff was off.
Shuffle Off
Cross Fading Off
Pitch Bend Off
Hijack Bass and Treble set to 0
EQ Locks Independant
Posted by: tfabris
Re: 5th Meet - 15/08/2004 19:35
May I say that I've also seen situations where the auto-EQ does not properly play the tones. Sometimes it works fine, and sometimes it locks up or makes odd noises. I don't think Andy is imagining it.
Posted by: Shonky
Re: 5th Meet - 15/08/2004 20:16
Quote:
The best feature of alpha8 is the extended memory support.
What about these then? If someone can tell me they are fixed or not I'll start harassing people for 3a8 or alternately I'll go back in my hole respectively depending on the answer.
Posted by: genixia
Re: 5th Meet - 15/08/2004 23:56
Oh, two more things to check... Hijack's L/R time alignment, and VolAdjust.
Posted by: image
Re: 5th Meet - 16/08/2004 16:15
Loudness also set to 0db.
Posted by: andym
Re: 5th Meet - 25/08/2004 19:35
Tried setting everything back to normal. Had another go and blew the HF driver on my front components. Oh well, looks like an upgrade is on the cards now.