stepped attenuator kits ?

jimbo1968 · 8th December 2005, 05:57 PM

I want to build a pre-amp box that will contain passive attenuator, a simple buffer and an active crossover. It will also let me switch sources between CD and AVamp, thus letting me remove the AV amp for music.

Opinion seems to be that stepped attenuator beats potentiometer, so does anyone know where I can get a kit of parts? Or can recommend where to buy the dual 12way switch (does it need to be a quality item?).

Maybe someone has a built attenuator for sale?

Tony D. · 8th December 2005, 06:07 PM

Here is one from www.diyfidelity.com

http://www.diyfidelity.com.au/index....a22fcb47d0eed9

T.D.

Vikash · 8th December 2005, 06:51 PM

I built a 12 step attenuator with parts from Farnell. Full details at Decibel Dungeon

jimbo1968 · 8th December 2005, 07:36 PM

thanks for those replies. I'm getting a shipping price for the built one. I have read most of decibel dungeon, but I hadn't spotted the pre-amp/crossover, exactly what I want.

hermanv · 9th December 2005, 05:29 PM

Quality is a relative term.

I built my passive pre using Shallco switches (coin silver contacts, high wipe, high pressure) bought at Michael Percy.

He also carries several brands of audiophile resistors priced from oh dear to oh my god.

12 steps seems minimal, if I were to do mine again I would choose steps of 1.5 dB in the nominal listening volume range. Outside that range I would expand to 3 dB steps and then maybe 6 or 10 dB.

A good design would probably run from -40 to +6 dB total range. So 3 steps of 6dB gets you from -40 to -28, then maybe 4 steps of 3dB gets you to -16. Now 7 steps of 1.5dB each gets you to -6.5 followed by 4 steps of 3 dB to get to +5.5. That's 18 steps, a lot of resistors.

My passive stacks up against the very best pre-amp sound quality I have ever heard. For all the work you are about to do, I would consider buying very good parts in order to make it the last one you'll ever build.

jimbo1968 · 9th December 2005, 10:03 PM

Thanks for the comments, I think I'll start with a mid-range unit though as I've only just added pre-amp to my list of things to build and I'm not ready for $300 attenuators yet.

Besides, if I started with a $300 shalco I wouldn't have anything to reference it against.

hermanv · 10th December 2005, 12:05 AM

The Shallco is only $94 it's the damn vishay resistors that run $300.

pblossom · 10th December 2005, 12:31 AM

You could also try
http://www.goldpt.com/

They have kits, as well as DIY instructions.

dnsey · 10th December 2005, 09:06 AM

Look out for Winkler stud switches. Expensive new, but available as military surplus sometimes. They come with silver- or gold-plated contacts, and are excellent in this application.

Paul Dimaline · 10th December 2005, 09:13 AM

White Noise Audio UK based and a nice guy to deal with.

8th December 2005, 05:57 PM	#1
jimbo1968 diyAudio Member Join Date: Nov 2004 Location: UK, bristol	stepped attenuator kits ? I want to build a pre-amp box that will contain passive attenuator, a simple buffer and an active crossover. It will also let me switch sources between CD and AVamp, thus letting me remove the AV amp for music. Opinion seems to be that stepped attenuator beats potentiometer, so does anyone know where I can get a kit of parts? Or can recommend where to buy the dual 12way switch (does it need to be a quality item?). Maybe someone has a built attenuator for sale?

8th December 2005, 06:51 PM	#3
Vikash diyAudio Moderator Emeritus Join Date: May 2003 Location: UK	I built a 12 step attenuator with parts from Farnell. Full details at Decibel Dungeon __________________ "The human mind is so constituted that it colours with its own previous conceptions any new notion that presents itself for acceptance." - J. Wilhelm. (But I still think mine sounds better than yours.)

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8th December 2005, 06:07 PM	#2
Tony D. diyAudio Member Join Date: Feb 2001 Location: Vancouver, B.C., Canada	Here is one from www.diyfidelity.com http://www.diyfidelity.com.au/index....a22fcb47d0eed9 T.D.

8th December 2005, 07:36 PM	#4
jimbo1968 diyAudio Member Join Date: Nov 2004 Location: UK, bristol	thanks for those replies. I'm getting a shipping price for the built one. I have read most of decibel dungeon, but I hadn't spotted the pre-amp/crossover, exactly what I want.

9th December 2005, 05:29 PM	#5
hermanv diyAudio Member Join Date: Apr 2004 Location: Northern California	Quality is a relative term. I built my passive pre using Shallco switches (coin silver contacts, high wipe, high pressure) bought at Michael Percy. He also carries several brands of audiophile resistors priced from oh dear to oh my god. 12 steps seems minimal, if I were to do mine again I would choose steps of 1.5 dB in the nominal listening volume range. Outside that range I would expand to 3 dB steps and then maybe 6 or 10 dB. A good design would probably run from -40 to +6 dB total range. So 3 steps of 6dB gets you from -40 to -28, then maybe 4 steps of 3dB gets you to -16. Now 7 steps of 1.5dB each gets you to -6.5 followed by 4 steps of 3 dB to get to +5.5. That's 18 steps, a lot of resistors. My passive stacks up against the very best pre-amp sound quality I have ever heard. For all the work you are about to do, I would consider buying very good parts in order to make it the last one you'll ever build.

9th December 2005, 10:03 PM	#6
jimbo1968 diyAudio Member Join Date: Nov 2004 Location: UK, bristol	Thanks for the comments, I think I'll start with a mid-range unit though as I've only just added pre-amp to my list of things to build and I'm not ready for $300 attenuators yet. Besides, if I started with a $300 shalco I wouldn't have anything to reference it against.

10th December 2005, 12:05 AM	#7
hermanv diyAudio Member Join Date: Apr 2004 Location: Northern California	The Shallco is only $94 it's the damn vishay resistors that run $300.

10th December 2005, 12:31 AM	#8
pblossom diyAudio Member Join Date: Jan 2004 Location: Michigan	You could also try http://www.goldpt.com/ They have kits, as well as DIY instructions.

10th December 2005, 09:06 AM	#9
dnsey diyAudio Member Join Date: Mar 2004 Location: Shropshire, England	Look out for Winkler stud switches. Expensive new, but available as military surplus sometimes. They come with silver- or gold-plated contacts, and are excellent in this application.

10th December 2005, 09:13 AM	#10
Paul Dimaline diyAudio Member Join Date: Feb 2004 Location: Lincolnshire, UK	White Noise Audio UK based and a nice guy to deal with.

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