About Attenuators - 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 3rd November 2002, 11:06 AM   #1
Account Disabled
 
Join Date: Sep 2002
Default About Attenuators

I would try some good slide potentiometers Penny & Giles, one advantage is if you mount them side by side you have a instant balance control I must admitt that the balance controls where not on my schedule but I have realized that one have to use a balance control of some type, it's most convenient if you don't want to move speakers.
One idea is to use reed relays, just the switch element, and build a sliding type of attenuator device these elements is rather cheap and I think very good switches say that one use 24 x 2 it is about 48 $ plus the resistors.
  Reply With Quote
Old 3rd November 2002, 11:37 AM   #2
Account Disabled
 
Join Date: Sep 2002
Default P&G

I found a rotary P&G with very good specs check this link http://www.pgcontrols.com RF 15 maybe it is very expensive but I think it will do the job much better then a stepped attenuator much because of the infinity resolution.
  Reply With Quote
Old 3rd November 2002, 11:42 AM   #3
diyAudio Member
 
Brett's Avatar
 
Join Date: Jan 2002
P&G = expensive for the performance. These attenuators are designed for studio mixing consoles and the like where repeatable precision in level is required. Because of all the open area, they're also a dog to keep clean. Remeber studios have a maintenance tech to do it all the time.

Reed relay = best relay for audio, especially the shielded types. If you build a shunt attenuator like the Aleph pre's, you will only need 8 to 12 a channel and you can get a 70dB range in 1 dB steps if you use high precision resistors (0.1%).

Even simpler is a shunt using an Alps or Noble motorised pot as the shunt element. They track within a dB or 2 over a 60dB range and are really cheap and easy to implement.
  Reply With Quote
Old 3rd November 2002, 12:36 PM   #4
diyAudio Member
 
mrfeedback's Avatar
 
Join Date: Feb 2002
Location: Perth, Australia.
leiade,
Alps make (made ?) a volume control with detented 1dB steps.
The range is 0dB down to -20dB then mute.
You could add a 20 or 40 dB pad before or after to give lower level control.
I had a system where 0dB from the cd player would drive the amp to momentary clip with the pots at max.
The detented level steps made repeatable level setting a piece of cake.

Eric.
  Reply With Quote
Old 3rd November 2002, 12:58 PM   #5
Account Disabled
 
Join Date: Sep 2002
Default Attenuator

Hi,

This is my idea, no fancy digital electronics that controls the attenuating device, just simple mechanics with cheap parts this results in a very precise audio attenuator.
You can make this at home with ordinary tools of course the resluts will be better if you have an mech workshop.
Use aluminium, brass and steel of some quality use ready sprocket wheels the pro type with sprocket belts fine for exact function.

Look at the coarse drawings it is NOT to scale I don't claim that this is the final solution but it is something to begin with here it is.
Attached Images
File Type: jpg atn.jpg (41.7 KB, 473 views)
  Reply With Quote
Old 3rd November 2002, 01:46 PM   #6
diyAudio Member
 
Join Date: May 2002
Location: wheeling illinois
The lecson preamp of the late 70's did this for all input
switching. Works great (till the magnet falls off)

remember to space the reed relays enough apart such that
the magnet only triggers one at a time.
  Reply With Quote
Old 3rd November 2002, 02:01 PM   #7
Account Disabled
 
Join Date: Sep 2002
Default Lecson

Yes I remember their obscure products I have tried to repair one of their power amp it was very hard to take apart, well I have done this drawing with this product in mind but nowaday we have better parts for doing this mechatronic attenuator I think no parts have to fell apart, with som extra care when assembling this device it would work for many years without any service.
It would also be very simple to make the adjustments for different kind of switchings.
Well, Dears Sirs come on let's make it who will begin.

I repeat the cost of this will almost be nothing and the resluts will be outstanding no Hallco, DACT or any have a fair chance.
  Reply With Quote
Old 3rd November 2002, 08:23 PM   #8
diyAudio Member
 
Join Date: Feb 2002
Location: Belgium
Have tought about that myself, but the space it takes held me back. It will create a very large loop that can pick up interference. Be careful with your layout.

Infinite resolution from a pot? Just try it! Use a very stable supply and a 6 digit voltmeter HP quality (Agilent now, but on those it will still be HP, they are that old). See if you can set it on whatever voltage you want and if you can repeat it.
  Reply With Quote
Old 3rd November 2002, 08:54 PM   #9
Account Disabled
 
Join Date: Sep 2002
Default Resolution

Ok!
If you draw everthing to it's end there is nothing that being what one think, nothing that we can create is perfect but some will be near, for example a high precision wirewound potentiometer from any good manufacturer but it is not cheap about 100 $ or more and it's linear so it makes something easier.I have seen some with 0.25% linearity or better over its whole length it was a 10 turn device, it may be used as a volume pot.
Remember not even a SKF ball is not exactly round.
BTW the small reeds they are about 1.8 mm so the total lenght may be about 65 mm depending on the space between the elements if you use 23 pcs.You also have possibilities to make a stepped click indicator option using the sprocket belt as template.
65 mm and good shielding practise may be worth a try I will build one prototype just to se if it is good enough for high end, I think so.If you have a good mech workshop you may even make this reed device look like a ordinary round switch.
  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
Attenuators stven Parts 0 12th January 2009 03:05 AM
Attenuators ------ Please Help soundbadger Tubes / Valves 5 13th February 2008 04:19 PM
Alps attenuators Miniwatt Tubes / Valves 11 16th January 2006 01:29 PM
Building Attenuators enzedone Chip Amps 3 23rd December 2004 10:00 AM
Any advice on attenuators? Jim B Solid State 3 5th May 2004 02:00 PM


New To Site? Need Help?

All times are GMT. The time now is 03:44 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2