attenuator selection

Dominick22 · 15th April 2006, 01:56 AM

I saw this on Ebay

http://cgi.ebay.com/for-Vintage-Ampl...QQcmdZViewItem

Is it any good?

I would actually like to spend a little less.

Any reccomendations??

Thanks,
Dominick

Dominick22 · 15th April 2006, 01:58 AM

This is for the LM4780 chips and I would actually like a 4 channel version but can make due with 2-2 channel models.

Dominick

Greg Erskine · 15th April 2006, 03:03 AM

hi Dominick22

Here it is for A$50

http://www.diyfidelity.com.au/produc...products_id=32

regards

Nuuk · 15th April 2006, 08:47 AM

Dominick22 - you need to know what impedance you require for the attenuator.

The one that Greg has pointed out is actually A$75 assembled and uses a different switch mech (that is actually more compact than the one on Ebay if space is at a premium! .

I have both types of attenuator and am pleased with them!

Dominick22 · 15th April 2006, 03:42 PM

hmm, I am sure this has been asked before, but how do I select impedence. In my current set up-I have used a carbon 10k and a cheapo from radioshack that was 100k. They both seemed to work fine?

So what is the difference?

Dominick

Nuuk · 15th April 2006, 07:07 PM

It depends on the output impedance of the previous stage (CDP , DAC etc) and the input impedance of the following stage (buffer/power amp).

Most CDP's will work OK into a 10K attenuator but the NOS DACs prefer 20-25K. Trouble is if you use an inverted GC or one of the class-T amps, they prefer a 10K attenuator so you need to buffer it.

jleaman · 15th April 2006, 07:39 PM

Dominick22,

The ebay link you have provided, that pot would be horrible in a amplifier. You can ask Briangt on this forum how fast the one he had in his chip amp came out. Id say less than 15 min. They make lots of noise they are clunky the attract signal too. Id have to say id never buy one again and never recommend one to any one either. I think if you want a nice pot for a amp your best bet is a nice alps pot.

Look at this picture. This is the pot i removed from Brian's chip amp and threw in the garbage.

http://www.briangt.com/gallery/lm3886amp/proto_amp_4

Nuuk · 15th April 2006, 07:57 PM

Quote:

The ebay link you have provided, that pot would be horrible in a amplifier. You can ask Briangt on this forum how fast the one he had in his chip amp came out. Id say less than 15 min. They make lots of noise they are clunky the attract signal too. Id have to say id never buy one again and never recommend one to any one either. I think if you want a nice pot for a amp your best bet is a nice alps pot.

I humbly bow before such great knowledge!

jleaman · 15th April 2006, 08:43 PM

Quote:

Originally posted by Nuuk

I humbly bow before such great knowledge!

Thats what the DIYAUDIO.com site is all about. We help each other out. I just wanted to warn you of this type of pot. You may spend that $$$ on a pair of pot's from http://www.percyaudio.com/

Jase

Greg Erskine · 15th April 2006, 08:55 PM

Hmmm.....

What about the one at diyfidelity then:

http://www.diyfidelity.com.au/produc...products_id=32

Is it really different? Is it good or bad? A lot of people seems to be buying them.

15th April 2006, 01:56 AM	#1
Dominick22 diyAudio Member Join Date: Aug 2005	attenuator selection I saw this on Ebay http://cgi.ebay.com/for-Vintage-Ampl...QQcmdZViewItem Is it any good? I would actually like to spend a little less. Any reccomendations?? Thanks, Dominick __________________ A real amateur enthusiast!

15th April 2006, 01:58 AM	#2
Dominick22 diyAudio Member Join Date: Aug 2005	This is for the LM4780 chips and I would actually like a 4 channel version but can make due with 2-2 channel models. Dominick __________________ A real amateur enthusiast!

15th April 2006, 03:03 AM	#3
Greg Erskine diyAudio Member Join Date: Jan 2002 Location: Sydney/Australia	hi Dominick22 Here it is for A$50 http://www.diyfidelity.com.au/produc...products_id=32 regards __________________ Greg Erskine

15th April 2006, 08:47 AM	#4
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	Dominick22 - you need to know what impedance you require for the attenuator. The one that Greg has pointed out is actually A$75 assembled and uses a different switch mech (that is actually more compact than the one on Ebay if space is at a premium! . I have both types of attenuator and am pleased with them! __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

15th April 2006, 03:42 PM	#5
Dominick22 diyAudio Member Join Date: Aug 2005	hmm, I am sure this has been asked before, but how do I select impedence. In my current set up-I have used a carbon 10k and a cheapo from radioshack that was 100k. They both seemed to work fine? So what is the difference? Dominick __________________ A real amateur enthusiast!


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15th April 2006, 07:07 PM	#6
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	It depends on the output impedance of the previous stage (CDP , DAC etc) and the input impedance of the following stage (buffer/power amp). Most CDP's will work OK into a 10K attenuator but the NOS DACs prefer 20-25K. Trouble is if you use an inverted GC or one of the class-T amps, they prefer a 10K attenuator so you need to buffer it. __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

15th April 2006, 07:39 PM	#7
jleaman Banned Join Date: Apr 2002	Dominick22, The ebay link you have provided, that pot would be horrible in a amplifier. You can ask Briangt on this forum how fast the one he had in his chip amp came out. Id say less than 15 min. They make lots of noise they are clunky the attract signal too. Id have to say id never buy one again and never recommend one to any one either. I think if you want a nice pot for a amp your best bet is a nice alps pot. Look at this picture. This is the pot i removed from Brian's chip amp and threw in the garbage. http://www.briangt.com/gallery/lm3886amp/proto_amp_4

15th April 2006, 08:55 PM	#10
Greg Erskine diyAudio Member Join Date: Jan 2002 Location: Sydney/Australia	Hmmm..... What about the one at diyfidelity then: http://www.diyfidelity.com.au/produc...products_id=32 Is it really different? Is it good or bad? A lot of people seems to be buying them. __________________ Greg Erskine

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