John Curl's Blowtorch preamplifier part II - Page 299

PMA · 20th November 2009, 07:16 AM

Quote:

Originally Posted by Allen Wright

Anyone actually also tried cermet critically?

The Vishay cermet is my favorite -

Yes, actually the Vishay cermet multiturn trimpot, in a Vbe multiplier.

john curl · 20th November 2009, 07:56 AM

As trimpots go, I would go for Vishay or a multiturn wirewound.

john curl · 20th November 2009, 03:41 PM

As far as rotary volume controls go, I find that TKD, Penny and Giles, Spectrol multi-turn wire, and custom discrete switches made into volume controls lead the list of 'A' rated attenuators.
'B' rated might be Alps, Noble, Bourns, etc. Not perfect, but pretty darn good.

Joshua_G · 20th November 2009, 04:14 PM

Thank you, John. I find it very useful info.

Netlist · 20th November 2009, 04:27 PM

I'm interested into what makes these particular brands A or B rated.
I would say that every brand has good and less good parts so if find the generalisation a bit difficult to accept 'As is'.
Can you be more specific, John? Application, environments...?

john curl · 04:38 PM

Listening experience is the best bet. Internal construction, especially substrate for conductive materials is another clue.
I work in a very competitive environment, and the best of the best, always goes for the A rated stuff, including the CTC Blowtorch (TKD), and the Ayre preamp (custom resistors and switches) We win listening contests with this as we challenge each other in the process.
Alps, for example, is in my 'B' line of products and has been for the last 30 years or so.
The Parasound JC-2 falls in this group, along with many other products, by other noted manufacturers. I have been able to hear the sound of the Alps BLACK dual pot in my STAX headphone amplifier, and I don't use that pot, anymore. The BLUE are pretty good, but if I can, I use TKD or P&G.

Netlist · 20th November 2009, 04:45 PM

Thanks, what about step ladder attenuators as the best? Of course, I realize it comes with a different price tag.

1audio · 20th November 2009, 04:56 PM

John:
I had a different experience with P&G in particular. I never liked what they sounded like and can't pin it down. The Alps and Nobels always seemed good as did the TKD's. but for the serious work we build controls from Tech Labs switches (similar to Daven) and either Holco (for the cash strapped) or Vishay resistors. 29 per switch and really tedious to build. The Vishay control sounded the best by far (totally subjective). I found a conductive plastic control from Bourns that seemed to be on a par with the Vishay. It was only available as a single gang. I don't know the part number any more. However at $1.50 ea. vs. about $300 ea. it was a very attractive solution. I had moved on from working with preamps at the time. I think this was the part: http://www.bourns.com/data/global/pdfs/Slimline.pdf

john curl · 20th November 2009, 05:11 PM

Well, Demian, this is what makes a 'horse race' Personally I find P&G a little 'soft' sounding, but that is OK for most program material.

john curl · 20th November 2009, 07:59 PM

I don't have much experience with commercial Ladder or shunt attenuators to be able to say anything important. It would be wonderful to know WHY volume controls make as much difference as they do. Still, I can't measure the good ones as especially different from each other, yet they sound different. I know that SY likes BLUE so that might be a factor for him. ;-)

20th November 2009, 04:35 PM	#2986
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	Listening experience is the best bet. Internal construction, especially substrate for conductive materials is another clue. I work in a very competitive environment, and the best of the best, always goes for the A rated stuff, including the CTC Blowtorch (TKD), and the Ayre preamp (custom resistors and switches) We win listening contests with this as we challenge each other in the process. Alps, for example, is in my 'B' line of products and has been for the last 30 years or so. The Parasound JC-2 falls in this group, along with many other products, by other noted manufacturers. I have been able to hear the sound of the Alps BLACK dual pot in my STAX headphone amplifier, and I don't use that pot, anymore. The BLUE are pretty good, but if I can, I use TKD or P&G. Last edited by john curl; 20th November 2009 at 04:38 PM.

20th November 2009, 04:56 PM	#2988
1audio diyAudio Member Join Date: Mar 2004 Location: SF Bay Area	John: I had a different experience with P&G in particular. I never liked what they sounded like and can't pin it down. The Alps and Nobels always seemed good as did the TKD's. but for the serious work we build controls from Tech Labs switches (similar to Daven) and either Holco (for the cash strapped) or Vishay resistors. 29 per switch and really tedious to build. The Vishay control sounded the best by far (totally subjective). I found a conductive plastic control from Bourns that seemed to be on a par with the Vishay. It was only available as a single gang. I don't know the part number any more. However at $1.50 ea. vs. about $300 ea. it was a very attractive solution. I had moved on from working with preamps at the time. I think this was the part: http://www.bourns.com/data/global/pdfs/Slimline.pdf __________________ Demian Martin Product Design Services

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20th November 2009, 07:56 AM	#2982
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	As trimpots go, I would go for Vishay or a multiturn wirewound.

20th November 2009, 03:41 PM	#2983
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	As far as rotary volume controls go, I find that TKD, Penny and Giles, Spectrol multi-turn wire, and custom discrete switches made into volume controls lead the list of 'A' rated attenuators. 'B' rated might be Alps, Noble, Bourns, etc. Not perfect, but pretty darn good.

20th November 2009, 04:14 PM	#2984
Joshua_G diyAudio Member Join Date: Nov 2008 Location: Israel	Thank you, John. I find it very useful info.

20th November 2009, 04:27 PM	#2985
Netlist diyAudio Moderator Join Date: Jan 2003	I'm interested into what makes these particular brands A or B rated. I would say that every brand has good and less good parts so if find the generalisation a bit difficult to accept 'As is'. Can you be more specific, John? Application, environments...?

20th November 2009, 04:45 PM	#2987
Netlist diyAudio Moderator Join Date: Jan 2003	Thanks, what about step ladder attenuators as the best? Of course, I realize it comes with a different price tag.

20th November 2009, 05:11 PM	#2989
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	Well, Demian, this is what makes a 'horse race' Personally I find P&G a little 'soft' sounding, but that is OK for most program material.

20th November 2009, 07:59 PM	#2990
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	I don't have much experience with commercial Ladder or shunt attenuators to be able to say anything important. It would be wonderful to know WHY volume controls make as much difference as they do. Still, I can't measure the good ones as especially different from each other, yet they sound different. I know that SY likes BLUE so that might be a factor for him. ;-)

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