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View Full Version : Matching a power amp to an intergrated or AV amp?



HighFidelityGuy
16-04-2009, 09:12
Hi,

I currently have an AV amp which has lots of speaker outputs and pre-amp outputs as they usually do. I currently bi-amp my speakers using 2 pairs of speaker outputs as the amp allows you to do this. My speakers are tri-ampable, so I have the option of getting a separate power amp and connecting this to the front pre-out to give me a tri-amp setup. That part I understand.

Where it starts getting complicated is matching a separate power amp to the internal amp. The AV amp manual says you must use a power amp that has 31dB gain, as if you don't the sound will be unbalanced, which makes sense. Unfortunately not all amp manufacturers supply the gain rating.

What I'm wondering is; is there anything else to consider like output or input impedance etc and is it possible to work out from other specs which amps will work together properly?

For example; my AV amp has a gain of 31dB, an output impedance of 600 Ohm and and output voltage of 2V RMS @ 0db gain (3.5V RMS max).

One power amp I'm looking at getting has a gain of 29dB, an input impedance of 47K Ohm and will generate full power from an input voltage of 1.13V RMS.

Will these two match together well or will the sound be unbalanced? :confused:

I'd be really grateful if someone could explain how this works to me. :)

Thanks,

David.

Alan
16-04-2009, 13:00
Does your AV amplifier manufacturer make a power amp from the same range? If they do there is a good chance they will be compatible. Otherwise it can be a little tricky to match amps - even if they match on paper they might not go well together, whilst another amp might not be quite the perfect match on paper, but sound pretty nice...:confused:

Worth sticking with though as Bi and Tri - Amping can pay handsome dividends when correctly done.

HighFidelityGuy
16-04-2009, 13:26
Yeah, it's Arcam so I could get one of there's and be sure that it will match but I like to keep my options open. :eyebrows:

The Grand Wazoo
16-04-2009, 19:33
I see elsewhere that you're going to go the 'one-make route'.

Anyway, for what it's worth, I'll let you know about my experiences with this.
I've been multi-amping for years & almost always with great results. The worst mismatch I had was with a mixture of Radford STA 15 driving the mids & the Levinson ML11 on the bass & treble. I got around this in several ways at different stages.

I had a pair of 20dB pads between the Radford and the pre-amp when I was using it to drive speakers full range (my SP8 pre-amp has enough gain on it's own to drive some speakers!!). So I tried this set up accompanied by the Levinson & it sounded good enough to know there was enough potential there to explore further.

I then made up a passive pre using a Sfernice pot to control the Radford. This was excellent with a very short interconnect between pot & power amp - long cables cause treble roll-off (I used an inch or so of cable - a bugger to construct though!).

In it's final incarnation, I made up a small chassis with several sets of output sockets & one set of inputs. I took the pre out into this & inside it I applied resistance as required or not by each amp (I was tri-amping with the Radford, a Cary, and the Mark Lev by then). This sounded brilliant, & in fact I was surprised by the effect of the input/output splitter box. I had several sessions of listening to each amp individually with & without it and in every case, it sounded better with the splitter than without - don't ask why.

Nowadays, my speakers are only bi-amp capable & I use two Mark Lev's (same vintage, same gain).

It doesn't take long to hear the advantages of multi-amping!

Alan
16-04-2009, 20:31
It doesn't take long to hear the advantages of multi-amping!

Amen! Testify, brother...:gig:

HighFidelityGuy
17-04-2009, 12:41
I've not fully decided whether to go the "one-make" route or not yet. As I mentioned before I'm keeping my options open and weighing it all up.
Currently after giving this some more thought I think that mixing and matching amps in a tri-amp setup is going to be beyond my patients and mainly beyond my budget. I can't really afford to invest in multiple amps and keep swapping and changing until I find the right balance. I was hoping there was a simple rule of thumb to follow that would simplify the process but that doesn't seem to be the case.

So I think I'm going to limit my self to two options to try and simplify things.
Option one is to get an Arcam power amp to add to my Arcam AV amp to give me tri-amping.

Option two is to get a big higher end power amp to add to my Arcam AV amp but to just use this to run the speakers on it's own. This would give me full flexibility on what make of amp to get. The down side of this is that it would cost more than option 1 and "waste" 4 amp channels I've already paid for.

Opinion seems to be a bit divided as to which of these options would be best out of the people I've spoken to about it. So I think my best option is to try both and decide for my self. That way I can't go wrong.

Alan
17-04-2009, 15:46
"Opinion seems to be a bit divided as to which of these options would be best out of the people I've spoken to about it. So I think my best option is to try both and decide for my self. That way I can't go wrong."

That is the way forward - you can't beat the satisfaction of learning & constructing a system for yourself. And, as you've found, there is loads of info & advice on forums to guide you when the waters get murky (as they will).

One make solutions (if you find a make you like) are the simplest approach to passive poly-amplification - but as you already have an amp you like I don't want to push that idea at you too hard as it involves significant outlay if you hit it in one go.

HighFidelityGuy
26-04-2009, 17:09
I managed to pickup a pair of Musical Fidelity 550K monoblocks over the weekend. They were on sale at £699 for the pair, down from £3000.:eyebrows: You've gotta love a bargain. Check out Unilet in Surrey if you're interested, be quick though as they're going fast.

They've definitely improved the sound. More detail, better imaging and sound stage and better dynamics etc.

I think I'm still going to borrow an Arcam power amp from my local dealer to try out tri-amping for comparison but I'll wait a month or two before then to give the MF's time to run in.

I'm currently using my Arcam AV amp as the pre-amp for the monoblocks but I did try running the mono's directly off my Beresford 7520 DAC and I think the sound was better. I'm going to try running them off the DAC again to double check. If running them directly off the DAC does sound better I have a bit of a dilemma as the DAC doesn't have a remote control for the volume, so I may need to pickup a pre-amp or something to get the best sound but that causes other complications. I'm going to have to give this some thought. :scratch:

muffinman
26-04-2009, 17:51
I managed to pickup a pair of Musical Fidelity 550K monoblocks over the weekend. They were on sale at £699 for the pair, down from £3000.:eyebrows: You've gotta love a bargain. Check out Unilet in Surrey if you're interested, be quick though as they're going fast.

They've definitely improved the sound. More detail, better imaging and sound stage and better dynamics etc.



Thanks for highlighting that deal, i'll look into it tomorrow. If there's none left then i can only assume that the credit crunch is not affecting audiophools :)

I tried to find out wether people had an opinion on the Quad 909 power to no avail. I'm looking to go valve pre (WDpre probably) -solid power in the future and as such want to get a good deal when it arises.
With that in mind, does anyone have an opinion on wether the 550kpr or the Quad 909 are any good?:confused:

HighFidelityGuy
26-04-2009, 17:59
They had an ex-demo 909 for £699 as well, I bet that's gone though. I was very tempted by it but decided to try the MF's instead. The MF's are a lot more powerful and more flexible because of their design. They also got a lot of good reviews at their original price, so I think at £699 they'll be very difficult to beat. The 909's are meant to be a very good amp as well though. They also had an ex-demo Rotel RB-1092 at £799. That's 500W per channel and also meant to be very good. Check out Unilet.net for the full sale price list. :)

muffinman
26-04-2009, 18:19
They had an ex-demo 909 for £699 as well, I bet that's gone though.


This is part of my problem. i've got a promise on a 909 (BNIB) for £500
the mfs' are more appealing at £200 extra though, oh for a third opinion :doh: