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 16th January 2014, 04:32 PM   #1
mqmq0 is offline mqmq0  Hungary
diyAudio Member
 
Join Date: Jan 2014
Default two amp in hafler's sound system?

Hi guys,
I'm not sure I'm posting it on a right section, if not please move it.

So my problem is:
I built the "poor man's surround" system on the other day with 2.1 pc speaker + 2.0 system (cut out the 2.0 amp and re-wired accordingly the haflers circuit). But, volume on the rear speaker are extremely low.
Is it possible somehow re-implement the 2.0's amp to amplifie the rear speakers?
I'm open to other solutions as well.

Last edited by mqmq0; 17th January 2014 at 11:42 AM.
  Reply With Quote
Old 18th January 2014, 02:36 PM   #2
mqmq0 is offline mqmq0  Hungary
diyAudio Member
 
Join Date: Jan 2014
anyone?
  Reply With Quote
Old 18th January 2014, 03:59 PM   #3
diyAudio Member
 
Join Date: Apr 2010
Location: Coffs Harbour, on the east coast
Let me get this right, you are talking about the ~1970 "Hafler-Dynaco" Quad adaptor ambience system ( a couple of Caps and resistors to connect a pair of rear speakers across +L and +R output terminals?

If so, the output level depends on the stereo difference between channels so some program will have almost no output as will central sources like the main vocalist, instrumentalist or bass. Phase correction is dependent on the resistors which further reduce output but as "ambience" speakers, they were not expected to be noticeable - just "there". I built a couple of boxes for this many years ago and even with high sensitivity speakers, the results weren't worth it. - too low an output with modern recording and sound mixing practice.

If you just want more volume, the rear speakers have to be boosted with another pair of amplifiers but this also requires a filter that mimics the system of in the original design. This is at preamplifier level, so small components can be used with higher impedance to suit the inputs. Really though, you are looking for a surround sound adaptor and that can be expensive.

Have a look at this project and the introductory details: http://sound.westhost.com/project18.htm
__________________
regards
  Reply With Quote
Old 18th January 2014, 04:17 PM   #4
mqmq0 is offline mqmq0  Hungary
diyAudio Member
 
Join Date: Jan 2014
I follow this description:
How to add Surround into a plain stereo system - Everything2.com
So basicly I just connected my 2 spare pc speakers between the +L +R in the 2.1 amp.
Now I have a spare amp circuit from it and I wonder can I use it somehow to amplify the rear speakers, connect it parallel or in series, just not sure how exactly.
Unfortunatly I can't open your link, its loading endlessly.

I'm not looking for a surround sound adaptor (atleast not right now) just I like to re-use old stuff and build something useful.
  Reply With Quote
Old 18th January 2014, 04:28 PM   #5
diyAudio Member
 
Join Date: Apr 2010
Location: Coffs Harbour, on the east coast
Yes that's the original Hafler-Dynaco arrangement circuit and won't do much, particularly not "near-field" as are PC speakers. The system was best in a large room with rear speakers closer (right behind you). The ESP site seems down here too, only in the last 30 mins.
__________________
regards
  Reply With Quote
Old 19th January 2014, 02:37 AM   #6
diyAudio Member
 
Join Date: Apr 2010
Location: Coffs Harbour, on the east coast
OK, the site is up again and link working. Given that you can't just rearrange speaker connections to achieve what you want, I think you'll find the discussion and circuits shown there aimed squarely at your needs, still low-cost.
__________________
regards
  Reply With Quote
Old 28th January 2014, 06:42 PM   #7
mqmq0 is offline mqmq0  Hungary
diyAudio Member
 
Join Date: Jan 2014
I'm wondering about this circuit since you showed me, and I think I'll try to build it soon, but one thing bothers me. There are no volume control for the rear speakers, any chance that I could change one of the resistors to a pot? And which one
  Reply With Quote
Old 29th January 2014, 02:38 AM   #8
Bare is offline Bare  Canada
diyAudio Member
 
Join Date: Dec 2001
Location: vancouver
Go here:
AK Database PDF Gallery - Dynaco/Dynaco ST120 Assembly/Owner's Manual
Download the Dynaco St120 assembly manual PDF.
Then go to page 6 for the Speaker wiring diagram for the "quad ' setup.
A simple early Hafler invention... No extraneous parts required.
  Reply With Quote
Old 29th January 2014, 03:30 AM   #9
diyAudio Member
 
Join Date: Apr 2010
Location: Coffs Harbour, on the east coast
Page 6 shows just another variation of the OP schematic discussed here. The only volume controls I have seen in these simple, unamplified arrangements is a 20-100R wirewound pot. or fixed resistors in series with the rear speaker pair or that centre, bridging speaker (if used).

In a local variation I saw at the time, 220 uF capacitors were used, connected in a non-polarised arrangement, to give some rear speaker phase shift. The volume was reduced further but you could hear a more believeable sound. Obviously, you can't increase volume this way in a passive circuit and there is going to be some interaction of controls.
__________________
regards
  Reply With Quote
Old 29th January 2014, 05:21 AM   #10
diyAudio Member
 
Join Date: Apr 2010
Location: Coffs Harbour, on the east coast
Quote:
Originally Posted by mqmq0 View Post
There are no volume control for the rear speakers, any chance that I could change one of the resistors to a pot? And which one
Which ESP shematic are you referring to? Both fig.2 & 3 schematics operate at line level (input signal plug level) and require amplification with, for example, your original set of powered speakers you described as "cut out".

Just reconnect the speakers in your original 2.0 system to their amplifier. You then have adjustable volume rear speakers when you connect the adaptor between the input signal and the 2.0 input socket. Note: you have to add shielded wiring to connect the signal from the 2.1 system input socket to do this.
__________________
regards
  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
Sound Code System Amp Specs?? Zero Cool Solid State 2 14th November 2012 04:19 AM
Sound Card Based Audio Test & Measurement System, 21-day fully functional Free Trial! VIRTINS Vendor's Bazaar 43 29th July 2011 03:10 PM
My sound system PROFESSOUR2003 Chip Amps 7 20th June 2010 04:51 PM
Hafler parts - Sound Valves? DMF Solid State 21 24th March 2010 08:12 PM
New sound system djfatben Multi-Way 16 17th December 2004 07:41 PM


New To Site? Need Help?

All times are GMT. The time now is 09:50 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