About volume control and input switching - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 11th August 2001, 08:51 PM   #1
diyAudio Member
 
Join Date: Aug 2001
Location: Kouvola, Finland
Hello all DIYers!

I'm having a preamplifier project going on (I am not the only one, I guess ). At first I thought the preamp would have semiconductor input switches and volume control (MAX4662 and CS3310), but then I looked at the Pass Labs Aleph P 1.0 service manual and saw how simplified the input switching and volume control was. Now I'm re-considering my own preamp design and I have some questions:

1. What kind of relays you would use for audio switching (of what brand / model).

2. Wouldn't the relays be really stressed when used in volume controlling (especially the "LSB" relay)? Do they last? Do I have to be afraid of connection failures and "static" in the sound?

3. Hasn't the development in solid state switches made them an alternative worth considering (recent switches have on resistance something like 2.5 ohms or less)?

Thanks in advance

Janne

ps. My first post here
  Reply With Quote
Old 12th August 2001, 09:36 AM   #2
diyAudio Member
 
promitheus's Avatar
 
Join Date: Jan 2001
Location: Germany
Hi there Janne,
Good luck in your preamplifier. The use of a relay is a very good idea. You donīt have to worry about any stresses on the relays. The currents are so small you wonīt have any problems. So donīt use big relays rated 5-10A. You can use ones rated at 1-2A. Try to find relays that are sealed from the enviroment like omron or siemens have . They are small in size and a few models are offered with gold or rhodium contacts for very long life. So if you find sealed relays with good contact material thats what you need.
About semiconductors, now that hard to say. They donīt seem to have the sound of simple circuits even if theoreticaly they are perfect. They are never used in high end circuits.
Anyway good luck again
Greetings
Ilias
  Reply With Quote
Old 12th August 2001, 01:24 PM   #3
diyAudio Member
 
Join Date: Apr 2001
Location: Germany
Default volume ctrl

Hi,

i find the aleph P 1.0 volume control very interesting.
It seems to be much simpler than the P 1.7's.
ADC0804 is a cheap 8-bit AD-Converter and the investment in 6 relays per channel seems reasonable.
Unfortunately the drive circuit is not shown in the service manual.
Service Manual location:
http://www.passlabs.com/pdf/Apserv10.pdf
volume ctrl circuit is on page 7.
What kind of input is expected on the "Ref B" input?

How can you make this attenuator move one step up and down?

The only thing that i want is a remote controlled ladder attenuator that can do without complex control computer etc (or at least i don't want to build the control computer).
I would use a kit remote control/receiver.
Any pointers to similar projects are appreciated.

Thanks,
Timo
  Reply With Quote
Old 13th August 2001, 10:19 PM   #4
hifi is offline hifi  Sweden
diyAudio Member
 
Join Date: Mar 2001
Location: sweden
what is not shown ?? the layout hmm ref b is from the PS thik it is 9,1 or 18,2 V from the zener stack...

if any body decides to draw a layout for the AD chip...plz mail it to me on hifi@hotbrev.com


/micke
  Reply With Quote
Old 13th August 2001, 11:20 PM   #5
diyAudio Member
 
Join Date: Aug 2001
The Sutherland Engineering Preamp uses the MAX335 serial switch for switching instead of relays and for volume control uses the LM1972. The only draw back is you will have to program a microcontroller to control both.

I have been told that the "Build Your
Own High-End Audio Equipment" book, available
through Old Coloney Sound Labs has some good volume
control schematics

For what its worth.
  Reply With Quote
Old 14th August 2001, 04:52 PM   #6
diyAudio Member
 
Join Date: Apr 2001
Location: Germany
Hi Micke,

Ok, only a voltage on Ref B. Fine.

And you adjust volume with what? The 100 k pot??

Regards
Timo
  Reply With Quote
Old 14th August 2001, 05:40 PM   #7
hifi is offline hifi  Sweden
diyAudio Member
 
Join Date: Mar 2001
Location: sweden
to my understandign yes...if you draw (a working) layout of the input part plz mail it to me on hifi@hotbrev.com

/micke
  Reply With Quote
Old 15th August 2001, 05:50 AM   #8
Ignite is offline Ignite  Canada
diyAudio Member
 
Join Date: Jul 2001
Location: Toronto, Ontario, Canada
Send a message via ICQ to Ignite
I actually went with a high-power l-pad. It works well. Thanks for the input, everybody.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Volume control on DVD player remote. Lose resolution at low volume? Circlotron Digital Source 2 10th June 2011 07:20 PM
help with my volume control, input selector, and other questions jufreese Chip Amps 5 26th March 2009 04:39 PM
Input selection and volume control with balanced output, transportable? jmaurer Solid State 0 11th August 2007 07:08 AM
Poll! What do you use in your X-BOSOZ or BOSOZ for Volume Control and Input Selector? promitheus Pass Labs 87 19th February 2006 03:15 PM
Need enlightments on GainClone input impedance and volume control Elkaid Chip Amps 10 8th April 2004 07:35 PM


New To Site? Need Help?

All times are GMT. The time now is 10:58 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2