Topic: Simple hack to increase SPL on AT853

[Chuck]

So Richard:

You replace the 27k resistor (in your famous black board battery box drawing) with the 4.7k resistor?

Chuck

You have two choices:

- two-wire configuration: replace my (27k) resistor with 4.7k, and use *standard* battery box.  (This has a 10k resistor in series with 9v).

- three-wire: what I drew previously.  That resistor can be anywhere from 5-30k and it will work.  The ideal value is about 10k for AKG CK9x capsules or 22k for AT853 (my previous value was a bit high).  Anyway, I often use 15k so I can use my boxes with both AKG and AT caps.

  Richard

Can you point me to the drawings of either one of these, new ways to wire them up?
In the "AT853 Three Wire Battery Box" drawing, there is no 10k resistor. Just the 27k.

I don't have the other drawing to reference...

[soundpro]

Hello all:

I spoke with an engineer at Audio Technica about the modification in this thread. He confirmed that it would lower sensitivity and increase the SPL capability of the AT853 mics.

He also said that it would lower the S/N ratio as the self noise will remain the same (lower sensitivity and same self noise=worse S/N ratio).

Thought you would all like to know this.

Best Regards,

Chris Carfagno
The Sound Professionals, Inc.
3444 Sylon Blvd.
Hainesport, NJ 08036
USA
www.soundprofessionals.com
Toll Free: 800-213-3021
Phone: 609-267-4400
FAX: 609-267-0054

[poorlyconditioned]

Hello all:

I spoke with an engineer at Audio Technica about the modification in this thread. He confirmed that it would lower sensitivity and increase the SPL capability of the AT853 mics.

He also said that it would lower the S/N ratio as the self noise will remain the same (lower sensitivity and same self noise=worse S/N ratio).

Thought you would all like to know this.

Best Regards,

Chris Carfagno
The Sound Professionals, Inc.
3444 Sylon Blvd.
Hainesport, NJ 08036
USA
www.soundprofessionals.com
Toll Free: 800-213-3021
Phone: 609-267-4400
FAX: 609-267-0054

Thanks for the info.

I'm not sure about the SNR though.  I think it might depend on where the noise is coming from, the FET or the electret element itself.

Hmm.  If it comes from the FET then you might lose some SNR.  Suppose you have a 10k load resistor (standard battery box).  Then adding the 4.7k resistor is like really having a ~15k load, but only "using" 10k of it.  Then you would expect to see a voltage output of (10k/15k) ~= 2/3 compared to the usual "three wire" circuit, with say, a 15k load resistor on the source.  So, the *power* loss is 20*log10(2/3) ~= -3.5dB.  That is what I would expect to lose on both sensitivity and on SNR (compared to the three wire).

Now, if the noise is coming from the Capsule itself, then there should be *no* loss of SNR.  Both the noise and the signal are attenuated by ~3.5dB.

Any other ideas?  Like from someone who knows electronics .

  Richard

[Church-Audio]

I don't know electronics as well as some on this board but, I will say that the increase in signal to noise, from having done this mod for over 10 years to panasonic capsules and the like is almost none  existant. And in a loud rock concert situation where you would need it I dont think you would ever hear the difference. Because the source would be so much louder then any self noise could ever be.

Chris Church

Hello all:

I spoke with an engineer at Audio Technica about the modification in this thread. He confirmed that it would lower sensitivity and increase the SPL capability of the AT853 mics.

He also said that it would lower the S/N ratio as the self noise will remain the same (lower sensitivity and same self noise=worse S/N ratio).

Thought you would all like to know this.

Best Regards,

Chris Carfagno
The Sound Professionals, Inc.
3444 Sylon Blvd.
Hainesport, NJ 08036
USA
www.soundprofessionals.com
Toll Free: 800-213-3021
Phone: 609-267-4400
FAX: 609-267-0054

Thanks for the info.

I'm not sure about the SNR though.  I think it might depend on where the noise is coming from, the FET or the electret element itself.

Hmm.  If it comes from the FET then you might lose some SNR.  Suppose you have a 10k load resistor (standard battery box).  Then adding the 4.7k resistor is like really having a ~15k load, but only "using" 10k of it.  Then you would expect to see a voltage output of (10k/15k) ~= 2/3 compared to the usual "three wire" circuit, with say, a 15k load resistor on the source.  So, the *power* loss is 20*log10(2/3) ~= -3.5dB.  That is what I would expect to lose on both sensitivity and on SNR (compared to the three wire).

Now, if the noise is coming from the Capsule itself, then there should be *no* loss of SNR.  Both the noise and the signal are attenuated by ~3.5dB.

Any other ideas?  Like from someone who knows electronics .

  Richard