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Question Can I combine Quad power amplifiers with any other pre-amp

pflik

Novice Member
Short story:
I want to drive my Magnepan 1.6QR with a quad poweramp.

Question: Are these poweramps compatible with every preamp or do they need to be combined with quad only pre amps? (i.e. 909 with a 99 preamp)

Long story:
It's been a while, but have slowly started to collect a modest system.
Currently I have:
  • Nad 3400 integrated amp
  • Magnepan 1.6qr
  • Magnepan SMGa
  • DIY Dual subs with an Hypex amp
As I just moved house, things are slowly starting to take place. It is becoming apparent that the Magnepan SMGa will be going to the study room and i'll most likely drive them with the Nad 3400.

In the living room will keep the Magnepan 1.6qr with the subs. However, I want to augment this with a 5.1/7.1/atmos setup. My idea is to have these cheap speakers for the surround channels (and front). Especially as watching movies is not really a priority (anymore...)

It is proving to be difficult to find a receiver that can properly drive these speakers and I'm thinking of getting a power amp to drive them and taking the left and right channel pre-outs from a receiver. This will give me some options in what receiver i can choose, as the requirements for the surround speakers are much less. (I would be able to drive them with 30/50 watt).

I know that the quads work very well with the magnepans. I've heard them live and it's absolutely stunning. However, i did understand that the older power amps (303 and i think 405 etc..) where not compatible with preamps other than the Quads. It had something to do with the input voltage being higher or lower that the industry standard.

Anyone that can enlighten me?
 

dogfonos

Prominent Member
As far as industry standards go, I wish there was a definitive answer to your question but, IME, there isn't. I thought that 750mV input for a power amp to give full output power was standard but I've seen many power amp input sensitivities (for full power output) range from 400mV to 1.5 V.

The Quad 405 gives full power output with just 500mV signal input, according to specs on Stereophile. That's a fairly low signal level for full output. I've not heard of an active pre-amp that outputs less than 500mV max. therefore most pre-amps (aimed at the domestic hifi market) would happily drive the 405 to full power - though I'm loath to state they all will. Best to check maximum voltage output of any pre-amp prior to purchase.

IME, most power amps will give full power for signal inputs exceeding 1V. Most active (hifi) pre-amps and DAC's output around the 1.5 to 2.0 V mark. Pre-amp output and power amp input voltages are often, but not always, different for professional products and some pro-sumer products to.

Other factors which could, in theory, affect compatibility between pre-amp and power amp, are output and input impedances. If a power amp has a particularly low input impedance then some (possibly cheaper?) pre-amps may not have a sufficiently sturdy output stage to drive them. Never come across this myself though.
 

pflik

Novice Member
hmm, other thing i will need to take into account... can i set the output voltage of the amplifier enough to be inline with the other surround speakers... Not only will the speaker itself have a impact on the volume, but also the fact that 0.5v into a quad amplifier will have a different volume than 0.5v into the internal amplifier.
 

Jampot90

Established Member
An older receiver with pre outs should fit the bill. Or any pre-pro but of course that means more power amps and cost. I have previously used an Arcam 350 this way with some success into Quad power amps (though not with Maggies) and presently use a Linn Akurate into a combo of Aragon 4400 (front L/R) and Quad 77 stereo power amps (bi-amped Quad centre and rear L/R).

All the quad amps have regular rca phono connections (or din in the very old ones) but the likes of the 77 /707/99/909 will only use remote functions when used in combination with the quad bus cables.

In my experience there should be enough adjustment in a decent receiver with pre outs) or pre-pro to balance channels in a multi channel application even with older amps with high sensitivity.

Unless you have a particular yen for the likes of a 303/306 or 405 (and are prepared to have them serviced) a 77, 707, 99 or 909 will be a simple solution as sensitivity is more conventional.

Jim
 

pflik

Novice Member
I was thingking about the 405 as a DIY package (i.e. get an old one and service it myself). But the other thought i had was to get a newer one (with sonic improvements). Specifically the 606 and the 909. I didn't have the 707 on my radar so thanks for the suggestion, i'll look into this.

I think the last thing i'm wondering, is the current dumping amplifier the best bang for buck given that i have a magnepan. I heard the Quads with a 20.6 magnepan, and it was stunning. However, i'm worried i might just be staring blindly at the brand and missing something much better for the money.
 

Paul7777x

Distinguished Member
From the 606 upward it would be difficult to do better than the quads for power per pound power amps.

Even the 405 has the current dumping ability, but noticeably less of it.

And as you’ve already heard the Quads and love them then they sound like the ideal amp for you.

Also, so far as I remember, Quad (at Huntingdon) can still service them to practically brand new spec should the need or desire arise.

Add the impressive power capabilities and I’d not look elsewhere.
 

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