Multichannel splitter and gain structure control box - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

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 23rd October 2012, 12:51 AM   #1
diyAudio Member
 
Join Date: Jan 2008
Location: Southern California
Default Line Level splitter/mixer and multichannel master volume control

I originally posted in the Multiway speaker forum and it was moved to this forum.

I figure that most people that have active crossovers and multiple subs need some type of solution to source and feed all the different amps. Hopefully some of you already have built something similar and will be able to assist.

I have been playing with both MINIDSP active crossovers and multisub setup to equalize room LF. The problem I always have is the gain structure of the MINIDSP. The minidsp likes a full line level signal. Using the minidsp for volume control is not good IMO.

Has anyone build something like this diagram below or know if something similar is commercially available for home use (small, nice looking unit).
Attached Images
File Type: jpg GSSV Network.jpg (193.8 KB, 240 views)

Last edited by avincenty; 24th October 2012 at 08:31 PM. Reason: clearer title
  Reply With Quote
Old 23rd October 2012, 08:55 PM   #2
diyAudio Member
 
linuxworks's Avatar
 
Join Date: Jul 2008
Location: santa clara, CA
I use an active xo and needed a multi way vol control.

currently, I'm trying out (and liking) the cs3318 chip. it gives 8ch and 3 master faders that you can assign the 8 chans to.

see my post on 'arduino and cs3318'. its not a pcb yet but its on its way to being one. I do plan a group buy once the proto stage is complete.

the attenuation is all in the analog domain even though control is digital.

that's my take on the 'how to match XO outputs to amps'

your box would need some extra mixing or summing but that's all I see as being different.
__________________
My Photostream:http://www.flickr.com/photos/linux-works/
  Reply With Quote
Old 23rd October 2012, 09:51 PM   #3
diyAudio Member
 
Join Date: Jan 2008
Location: Southern California
Looks really good! Like you say, I would still need the splitting/mixing portion.

I think the box could be quite flexible. The drawings below are applicable for multiple sub woofers, but similarly it can be applied to 2/3/4 way active crossovers.

I have been researching and I am initially leaning towards using DIY B1 Pass buffers and a LDR master volume control.

If I add input selection I might be able to eliminate my existing preamp from the chain. I have started to purchase some of the components already.
Attached Images
File Type: jpg MiniSW Pre.jpg (303.4 KB, 200 views)
File Type: jpg SW Pre.jpg (284.7 KB, 179 views)
File Type: jpg SW Looped.jpg (264.5 KB, 172 views)
  Reply With Quote
Old 24th October 2012, 12:46 AM   #4
diyAudio Member
 
linuxworks's Avatar
 
Join Date: Jul 2008
Location: santa clara, CA
I'm not sure ldr's are best if you have to gang them (multi channel). but that's a religious discussion and some people like ldr's.

my needs are at least 4ch (for a 2way active xo spkr system), and ideally 5way to include a discrete sub. doing 5 is the same as doing 6. the cirrus chip supports 8, so there's room left over

the neat thing about multichannel chips is that you have accurate atten on all channels and its atomic (you set one value and they all 'run' at the same time, at least in theory). you set offsets between them and they stick.

its like relays: they work well when there are only a few channels. but as you want more channels and you want them to 'click' at the same exact time, as you vary the vol knob, relays just don't scale (numbers of boards of them, that is).

the solid state way seems to be best, but you are free to choose the method you think best. at least consider the solid state solution.
__________________
My Photostream:http://www.flickr.com/photos/linux-works/
  Reply With Quote
Old 24th October 2012, 01:01 AM   #5
diyAudio Member
 
Join Date: Jan 2008
Location: Southern California
From where do you source the multiple inputs? Do you just do Y's on the stereo pair line level?
  Reply With Quote
Old 24th October 2012, 01:10 AM   #6
diyAudio Member
 
linuxworks's Avatar
 
Join Date: Jul 2008
Location: santa clara, CA
if you are asking about summing, it would be some resistors that come together at the input of a buffer or amp stage.

with that building block, you could sum inputs or outputs. then that would be a new 'channel' (when I see your L+R stuff).
__________________
My Photostream:http://www.flickr.com/photos/linux-works/
  Reply With Quote
Old 24th October 2012, 02:00 AM   #7
diyAudio Member
 
Join Date: Jan 2008
Location: Southern California
My question was about your implementation, but I just realized that you are going from your line source into the active crossover and from there you get the sources for the master volume. You have the signal splitting/buffering inside your active crossover.
  Reply With Quote
Old 24th October 2012, 05:01 PM   #8
diyAudio Member
 
Join Date: Jan 2008
Location: Southern California
Default Master Volume Proposed Circuit

Here is the master volume proposed circuit, I simply took the respective designs and spliced them together.

Pass Labs B1 Buffer

DIY LDR Attenuator

There is a circuit from Nelson Pass with both the LDR attenuator and a Buffer. That one requires a complimentary to the 2sK170 that is hard to get and would not be cost effective for me. The B1 uses two 2sk170 per channel. I got the 2sk170 for $0.38 each at MCM electronics (hope they are not fakes). Bought plenty so I can match pairs.

My plan is to use a large DELL 19V laptop power supply to power it. I will definitely have to test if in the end I will have enough gain for my system. I think I will, I have >95db speakers.

I am now drawing up the Splitter and Mixer circuit, will post it once done.
Attached Images
File Type: jpg Master Volume Circuit.jpg (207.1 KB, 162 views)
  Reply With Quote
Old 24th October 2012, 05:38 PM   #9
diyAudio Member
 
Join Date: Jan 2008
Location: Southern California
Default First Pass at Splitter and Mixer Circuit

For the Splitter buffers and mixers I also used the B1 buffer. I just put modules back to back. I think I may be able to remove either the 10uf Cap on the input L & R buffers or all the 1uf on all the output buffers. Can someone confirm if my thinking is correct.

Does the mixing seem correct? Will I need to attenuate the L+R outputs?
Attached Images
File Type: jpg Splitter and Mixer Circuit.jpg (173.0 KB, 61 views)
  Reply With Quote
Old 24th October 2012, 07:00 PM   #10
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007

Moved to Analog line level forum at OP's request as this will concentrate on the analogue signal stages.
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  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
What is Gain Structure? Pano diyAudio.com Articles 106 2nd August 2014 02:24 PM
multichannel volume control SashaV Analog Line Level 6 18th February 2012 06:42 PM
Multichannel volume control sumacSK Analog Line Level 0 31st December 2010 05:07 PM
help on amp gain structure nicoch58 Tubes / Valves 3 17th December 2010 12:09 AM
multichannel volume control coloradosound Parts 21 21st November 2007 05:24 PM


New To Site? Need Help?

All times are GMT. The time now is 11:49 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