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bencat

Will two identical Amplifiers with different Smoothing capacitors sound different

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Super Wammer

I am going to put this here and in the Technical section as I want the answer from two different view points .

I have an active speaker system I have made at home with a pair of KEF 103 Speakers with the passive crossovers removed and the driver connected directly to four 4mm inputs . I use a MiniDSP DDRC 24 unit to provide both the digtial crossover and a DIRAC Live DSP room filter .

The Speakers are powered by a pair of Quad 405 amplifiers that have both been converted by Fidelle Audio and input and output matched . So far so simple . However one of the 405 units has already been fitted with a pair of 10,000uF Elna Cerafine mains smoothing Capacitors while the other as advised by Peter at Fidelle was fitted with two 15,000uF Gold Tune Capacitors .

So all things being equal these are two fairly identical amplifiers except of this one component . Should this make any sonic difference ? Would this make any difference in the amplifiers overall ability to perform ?

It was my intention to fit these amplifiers one per speaker with each amplifier handling the bass output on the right channel and the treble output on the left cahnnel for each speaker . So a single stereo amplifier for the left speaker and the other stereo speaker for the right speaker.

Currently I have tow amplifiers one of the Qaud 405 units for the bass for both speakers and a Trio Basic poer amplifier for the treble for both speakers . This currently sounds very good indeed .

So when the second Quad comes back would it still be better to go with the one amp one speaker or use the 15,000uF amp for the bass and the 10,000uF for the treble .

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They should sound the same in my opinion .. the larger caps fitted to one may improve transient response when the amps are being run at full power (but I could be wrong) but as long as the capacitors used are equal to or greater than the originals you probably will not notice any difference.  This may prove of assistance https://www.electronics-notes.com/articles/analogue_circuits/power-supply-electronics/capacitor-smoothing-circuits.php

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IMHO, FWIW, my gut feel is you're unlikely to hear a difference but I guess if you have the option of hooking it all up, do it and have a listen.

My (probably foo) tech thinking says that it may make a difference to the level of signal filtering, which all depends on whether you've got anything other than 50hz on your mains in the audio band, although even the smaller size is already well big enough I expect.

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Moderator
2 minutes ago, awkwardbydesign said:

Of course you could bi-amp horizontally rather than vertically if you are worried about this.

This. At least then it won't be nagging at the back of your brain while you are listening to it.

Having said that, I very much doubt that you would hear a difference between the two amps.

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Super Wammer
5 hours ago, awkwardbydesign said:

Of course you could bi-amp horizontally rather than vertically if you are worried about this.

Okay I give in what does this mean ?

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35 minutes ago, bencat said:

Okay I give in what does this mean ?

I think horizontally refers to your suggestion (in your question) to use one for bass, and the other for treble.  Vertically would be one for one channel, and t’other for the other channel. 

For me the psychology of knowing they aren’t identical would make me go ‘horizontal’.  (A bit like I could never have speaker cables a different length as I’d imagine it would unbalance the sound!)

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Super Wammer

I should come out with what I believe here and that is that this very small difference will not make any difference . My gut feeling (because I do not have the technical knowledge or experience) is that a single amp for each speaker is the better option as it means each amplifier is completely electrically seperate (zero crosstalk) and both amplifiers will be fed similar signals meaning they will both have similar stress .

As I note I have no proof for this and the system does sound very good in its present mode with amplifiers for bass and treble . This was only done however because I am using very different amplifiers with different input and output sensitivities . Now DIRAC LIve takes this in to account when you run a measurement session and changes the sensitivities of each to compensate .

I think that with two of the same specified units that have very recently both been worked to match that this will be less nessesary but DIRAC will still make any changes should there be any differences .

I know it would be interesting to try this just because i can but it will mean that I will have to run a full measurement session between each change as it may well change the readings by altering the drive line up . That is only extra time for me but will mean there would be a very long delay between being able to listen to each set up and this is never good for comparison as audio memeory is not very accurate.

What I think I will do is put the reurned 405 straight in in place of the Trio amp and run a measurement . Give that a listen for three or four days and then change the set up to one amplifier per speaker and see how that sounds . Unless I can notice a real difference and a preference I will leave this set up in place and use that for the future.

Will drop a line here when this is completed so probably about ten - fourteen days from now.

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Super Wammer

Personally I would use one amp for Bass duties, and one for treble, that way the pair of speakers are getting the same power output.

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Super Wammer
Just now, greybeard said:

Personally I would use one amp for Bass duties, and one for treble, that way the pair of speakers are getting the same power output.

And also, 'IF' there is any difference between the amps, that fact they are working across different frequency ranges would mean that any potential minor difference will be hidden. 

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Even I would prefer going the horizontal bi amp route, with the amp with the larger smoothing capacitors doing bass duties :)

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Super Wammer

Well I now have the two Quads back and working . Wednesday and Thursday I ahd them set up with one for the bass and one for treble . It sounded good but if i am honest not as good as the Trio/Quad set up (and yes I did do a complete new measurement for DIRAC Live with Quads) .

Today I have amde the complete set up switch and gone with a single stereo amp for each speaker . This sound s not only better than the Quad/Quad for Bass and Treble oit also sounds better than the Quad / Trio arrangement . In fact it is now the best sound I have been able to get out of this system todate with the main improvement now being seperation and imaging which is much stronger .

I have no thought that any of this is due to the different Mains Caps i just think for me in my system this arrnagement works and sound better.

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Glad you have it working well - I look forward to hearing them at Kegworth!

Edited by Tony_J

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Super Wammer
3 minutes ago, Tony_J said:

Glad you have it working well - I look forward to hearing them at Scalford!

Freudian slip Tony or deliberate , I think you mean Kegworth . I am looking forward to being there as I enjoyed last years so much but I am also dreading it a bit . I have been a little over zealous with posts about this and that and I realised today that all of this has been done in a small spare room on a system that only i really listen to . My Wife Linda did pop her head in before and say that the last track (Solomon Burke) sounded very good so I hope that I am getting it right . But you alwasy worry that maybe it is just to your personal taste and will not translate to a wider audience . We will have to see .

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3 minutes ago, bencat said:

Freudian slip Tony or deliberate , I think you mean Kegworth . I am looking forward to being there as I enjoyed last years so much but I am also dreading it a bit . I have been a little over zealous with posts about this and that and I realised today that all of this has been done in a small spare room on a system that only i really listen to . My Wife Linda did pop her head in before and say that the last track (Solomon Burke) sounded very good so I hope that I am getting it right . But you alwasy worry that maybe it is just to your personal taste and will not translate to a wider audience . We will have to see .

Yes, Kegworth - brain fart there.

As you say, it's difficult to know how the system will come across in a hotel room, and never sure whether it really sounds any good until someone else confirms it for you. Mine have been developed in a much less-than-ideal setting - too close together, firing slightly obliquely across the room, lots of other crap stuff littering the room (it is our study, so 3 desks, bookshelves, etc. etc., plus two small Serama Bantam chicks cheeping away in a cage in the corner because they are too small to survive outside) - so the fact that they sound presentable in here is remarkable really. But I guess that is all part of the fun...

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