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How to parallel amps |
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Muckerbarnes1 
Old Croc 
Joined: 20 March 2010 Location: Stroud Status: Offline Points: 2654 |
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 Posted: 16 March 2018 at 1:42am |
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Sniggers like Mutley
 , politely. As Alan has correctly pointed out the capability of the average op amp is more than capable of driving several amp inputs, depending on the amp input impedance and of course the resistance in the mixer o/p after the final op amp. It may have a 0.3R output impedance (which is awesome), but if loaded at such with a suitable PSU, it would burn up very, very quickly. This not the case. The output impedance of the mixer on average as stated Vs the input impedance of the amps is a NO BRAINER. You could of course calculate the drop in gain by adding several amps, which will of course be negligible and pointless. You could also look at the more serious change in frequency Vs gain, but will then need much, much more info, and STILL it will be feck all. I'm older than Alan, and maybe I did not pay attention and learnt nothing in electronics, however resistance calculations we did at school in physics in 1972. ( honest guv) I remember it well. I did this whilst setting fire to something. Anyway, what am I blabbin' on about. Just connect the buggers up fer Pete's sake. Many a time I've had 10 amps on the SAME input chain. Works the same the world over. So for the OP... Just do it if you ARE serious about sound.  |
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Billy Dawg.
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mini-mad
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Joined: 13 July 2012 Location: london Status: Offline Points: 6903 |
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Posted: 16 March 2018 at 10:34am |
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THAT'S WHAT I KEEP SAYING!!!!!!!!
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If it sounds like a gorilla is trying to escape, turn it down.
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Earplug
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Joined: 03 January 2012 Location: Europe Status: Offline Points: 7216 |
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Posted: 16 March 2018 at 12:54pm |
Let´s see if this can get to (at least) 10 pages, c´mon...  And obviously power supply in the US is weaker than anywhere else in the world. +/-15V rails drop to 0 under the minimum stress.  |
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Earplugs Are For Wimps!
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Meat
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Joined: 05 June 2009 Location: Manc Status: Offline Points: 1514 |
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Posted: 16 March 2018 at 1:14pm |
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Pardon my ignorance but in the context of opamps is there a concern regarding damping factor like when running speakers? Would you expect the bass to get flabby as you run more and more in parallel?
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Don't test the champignon sound
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DMorison
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Joined: 14 March 2007 Location: Aberdeen Status: Offline Points: 1649 |
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Posted: 16 March 2018 at 1:36pm |
Nothing wrong with asking the question, that's how loads of us learn Anyhoo, short answer - no damping factor to worry about. Reason: A large subwoofer cone has physical momentum when it's moving, and when the signal stops, that momentum will make it want to carry on moving, causing an "overhang" of sound after the signal from the amp stops. That is what damping factor from an amp is really trying to control. With direct electronic connection, there is no physical moving component, hence no momentum to be damped. Cheers, David.
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APW
Young Croc 
Joined: 13 November 2012 Location: Kent, UK Status: Offline Points: 1174 |
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Posted: 16 March 2018 at 1:40pm |
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As above....
A speaker is an electro-mechanical device i.e. it has moving parts..... Damping factor is the ability of the driving amplifier to control (or dampen) unwanted mechanical movement in the speaker’s cone & motor due to their moving mass, this is not an issue here as we have no mechanical movement. Edited by APW - 16 March 2018 at 1:42pm |
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Meat
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Joined: 05 June 2009 Location: Manc Status: Offline Points: 1514 |
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Posted: 16 March 2018 at 5:11pm |
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Thanks, for answering my slightly off-topic question, that makes perfect sense.
In terms of the main subject here; what is the reason that we see earlier posters saying that Lab Gruppen recommend only using a daisy-chain of 4 amps? Is this to do with some other property of the circuit or just what they deem as being best practise? I'd assume that they're issuing advice based on some reasoning..? |
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Don't test the champignon sound
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Jo bg
Young Croc
Joined: 08 March 2017 Status: Offline Points: 552 |
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Posted: 16 March 2018 at 6:00pm |
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Hi
With the manual in my hands it literally states that " a typical source can drive up to 4 amplifier channels before external line drivers MIGHT BE required to buffer the signal". I does not say that over 4 amps you NEED a line driver, but they don't know what you are feeding the amp with, so with some sources with high output impedance you could need it, but they assume up to four should not need it, and 5 is not such a different load I think. They are just being very cautious as far as I can see |
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Earplug
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Posted: 16 March 2018 at 6:23pm |
There is a big difference between low (line) level signal processing and driving speakers. Opamps work with voltage rails around +/-15V-18V and milliamps, power amplifiers with voltage rails from the 20´s to the 100´s and need to supply real amperage. |
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Earplugs Are For Wimps!
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dylan-penguinmedia
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Joined: 14 April 2011 Location: Brighton Status: Offline Points: 4575 |
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Posted: 16 March 2018 at 6:40pm |
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Just daisy chain them passively.
It’ll be fine. NEEEEEEXXXXXTTTTT! |
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mini-mad
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Posted: 16 March 2018 at 7:26pm |
I've been repeating that and we're up to 5 Damn pages now..... Edited by mini-mad - 16 March 2018 at 7:26pm |
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If it sounds like a gorilla is trying to escape, turn it down.
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dylan-penguinmedia
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Posted: 16 March 2018 at 8:30pm |
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Did someone say something?
Naah, must be the wind! 
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mini-mad wrote: