Aleph P with balanced shunt attenuator

lauret · 10th May 2010, 08:44 AM

Hello all,

I'm using my Aleph P1.7 right now single-ended with a 10K 41-step 1,5dB-per-step series attenuator on the output from Acoustic Dimension. Would it be possible to use this attenuator in a balanced series-shunt attenuator like shown on the right side in this picture:

Ok, I have three questions regarding this setup:
Any drawbacks in this configuration? Is the Aleph P1.7 up to this config? And lastly what should be the value of the series resistors?

Thanks!

Bill Fuss · 10th May 2010, 10:10 AM

It should work OK, I would try 1k for starters.

lauret · 02:30 PM

Quote:

Originally Posted by Bill Fuss

It should work OK, I would try 1k for starters.

Just for learning purposes: what is the reasoning behind 1k?

BTW, can I still use it SE when configured in the balanced shunt way?

Bill Fuss · 10th May 2010, 09:07 PM

That's a good question. Referencing the signal to ground, it would surely change the response. After thinking a minute, no, it wouldnt work correctly single ended. A simple DPDT switch would work though, switching the bottom of the att. from ground to the other output.

1K is just a guess as you are using it as a variable voltage divider.

Nelson Pass · 11th May 2010, 02:13 AM

Maybe a little higher - 5 to 10k

lauret · 11th May 2010, 06:19 AM

Quote:

Originally Posted by Bill Fuss

That's a good question. Referencing the signal to ground, it would surely change the response. After thinking a minute, no, it wouldnt work correctly single ended. A simple DPDT switch would work though, switching the bottom of the att. from ground to the other output.

I see that the D1 also uses such a volume control, but there it is squeezed between active circuitry. So that would be the condition for both the functioning of SE and balanced without a switch?

Bill Fuss · 11th May 2010, 11:20 AM

I'm not familiar with the D1, but I bet that other poster knows something about it.

daly41k · 11th May 2010, 02:41 PM

If you go to Erno Borbely's web site you will find a tweak for a balanced volume control that looks very similiar to yours that he recommends for use with his equipment. You can compare the resistors used in the balanced arrangement. I have tried it and it works fine. dave

dobrivoje · 12th May 2010, 08:47 PM

Go to Uskok_Preamplifier. There you'll find exellent balanced attenuator. Some text is Croatian, but drawings are in English.

DiyFan · 13th May 2010, 01:54 AM

This site: Shunt Pot Volume Control - World-Designs-Forum shows how to calculate values for shunt controls.

Sean

10th May 2010, 08:44 AM	#1
lauret diyAudio Member Join Date: Oct 2007 Location: Amsterdam	Aleph P with balanced shunt attenuator Hello all, I'm using my Aleph P1.7 right now single-ended with a 10K 41-step 1,5dB-per-step series attenuator on the output from Acoustic Dimension. Would it be possible to use this attenuator in a balanced series-shunt attenuator like shown on the right side in this picture: Ok, I have three questions regarding this setup: Any drawbacks in this configuration? Is the Aleph P1.7 up to this config? And lastly what should be the value of the series resistors? Thanks!

11th May 2010, 02:41 PM	#8
daly41k diyAudio Member Join Date: Feb 2007 Location: Phillipsburg, New Jersey	balanced attenuator If you go to Erno Borbely's web site you will find a tweak for a balanced volume control that looks very similiar to yours that he recommends for use with his equipment. You can compare the resistors used in the balanced arrangement. I have tried it and it works fine. dave

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10th May 2010, 10:10 AM	#2
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	It should work OK, I would try 1k for starters.

10th May 2010, 09:07 PM	#4
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	That's a good question. Referencing the signal to ground, it would surely change the response. After thinking a minute, no, it wouldnt work correctly single ended. A simple DPDT switch would work though, switching the bottom of the att. from ground to the other output. 1K is just a guess as you are using it as a variable voltage divider.

11th May 2010, 02:13 AM	#5
Nelson Pass The one and only Join Date: Mar 2001	Maybe a little higher - 5 to 10k

11th May 2010, 11:20 AM	#7
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	I'm not familiar with the D1, but I bet that other poster knows something about it.

12th May 2010, 08:47 PM	#9
dobrivoje diyAudio Member Join Date: Aug 2009 Location: Smederevo, Serbia	Go to Uskok_Preamplifier. There you'll find exellent balanced attenuator. Some text is Croatian, but drawings are in English.

13th May 2010, 01:54 AM	#10
DiyFan diyAudio Member Join Date: Jun 2004 Location: Pacific NW	This site: Shunt Pot Volume Control - World-Designs-Forum shows how to calculate values for shunt controls. Sean

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