My system is feeling pretty tube-y and I was looking for suggestions of a solid state amps that people are liking with their original Quad ESLs. Looking for more speed and more of the bass I know the Quads can put out if set up right.
I found this exerpt from The Complete Guild To High End Audio. "Some amplifiers barely increase their output power when driving 4 ohms; others can double it. This means that not all 100wpc amps are created equal. One 100wpc amplifier might put out 150w into 2 ohms, while another might deliver 350wpc into 2 ohms. This ability to drive low-impedance loads (specifically, to deliver lots of current) has a large influence on an amplifier's sound and subjective power capability. This is where our dBW rating again comes into play. When calulating dBW, subtract 3dBW from the 8 ohm dBW rating when the amp is driving 4 ohms, and subtract 6dBW when the amp is driving 2 ohms. In the example of of the two 100wpc amplifiers in the preceding paragraph, each is rated at 100wpc into 8 ohms, or 20dBW. But the first amplifier puts out only 150wpc into 2 ohms, while the second puts out 350wpc into 2 ohms. Converting the 2 ohm power ratings into dBW, we see that the first has a dBW rating of 15.76 at 2ohms, while the second has a dBW rating of 19.44dBW into 2 ohms. Quite a difference-nearly 4dB-between two 100wpc amplifiers."
He doesn't explain why you have to subtract 3dBW when driving 4 ohms as opposed to 8 ohms but I have read this elsewhere also.
Maybe some transitor amps run out of voltage when trying to drive a high impedance load and thats why there is a tonal imbalance? Or am I wrong about this?
Hi Sean, Whatever that was that you read is misleading- it violates Kirchoff's Law, the law of electrical energy conservation. IOW if you put 100 watts into 4 ohms or 100 watts into 8, the output will be the same if the speaker efficiency is the same.
Atmasphere, Thanks for setting me straight. I have no experience with quads and Atmasphere's knowledge is much more complete than mine. So it looks like a tube amp is the best course.
I read somewhere that for instance if 100 wpc into 4 ohms produces 100db spl then 100 wpc into 8 ohms should produce 103 db. I think it was a car stereo book. It seemed to say that every time you half the impedance you loose 3 db of output. This seems to contradict what you are saying. Does what they are saying only apply to the voltage paradigm and not the current paradigm. I've read many of your posts about this and I still don't quite understand it all.
Sarcher30, Innersounds are built with lower impedances in an effort to make the speaker more compatible with transistors. The Quad ESL 57 has a peak of more than 50 ohms in the bass; there simply are not a lot of transistor amplifiers that can drive a load like that with any power.
To give you an example, let's try a 200 watt SS amp, which does 400 watts into 4 ohms. Into the Quad, it will be limited to about 30 watts in the bass. OTOH, it will be able to make 500 watts at high frequencies! Its easy to see why people perceive such amplifiers as very bright and no bass when used on the ESL 57.
Never used them with the speakers, but based on Atma-sphere's comments, it is possible that the older Pass Aleph amps might work in terms of the impedance issues mentioned - they are of course very good sounding SS amps, but the matching issue may be handled by the Aleph's output into changing loads, if I rememebr correctly, they worked much like tubes in that sense.
The Quads will only take a limited amount of power and can be damaged by over driving. I never had any trouble as I was careful with the volume but one of my customers bought 63s and a Musical Fidelity 270 [100 Watts?] and had to have them repaired 3 times because he constantly over drove them. A big amp is fine used with care.
That's interesting! I have two Parasound Halo JC1s but never thought these are good amps also for the Quads ESL Do you think they are good on the Quad ESL63 too?
It does sound like maybe I'm barking up the wrong tree. Maybe it's a front end issue. I have heard the JC1's sound great with Quads but they are out of my price range unfortunately....
The transistor amps will not give you what you want , in my opinion. I have been a confirmed user of transistors since I built a Heathkit in 1963 and was a Quad dealer for 15 years. Transistors are undoubtedly faster on cone speakers , because of higher dampening factor among other considerations. But these factors do not apply to the Quad, which is already faster than any cone. When I was a dealer I drove my 63s with Krell, Musical Fidelity and Stax class A solid state amps but could not detect a difference in speed or bass between them and good tubes. A friend drives his 57s, which I sold him in 1975, with a rebuilt Heath tube amp , it sounds as good as anything I have ever heard drive them. Foster Blair rebuilds them, they are available through Mapleshade. This is one case where having a transformer in the line helps the sound. After all, they were designed with a lower powered tube amp in mind. If I wasn't happy with the sound of the 57s driven by a good tube I would look at another speaker, they are what they are and the amp will not change them that much.
Given Atmasphere's explanation, maybe this is why some find that the old Quad 303 works reasonably well with Quads. It is solid state, but my understanding is that its power output actually drops as impedance drops. There are a few firms that do updates, like Net Audio or the new one that advertises on EBAY.
Bass is hard to get with transistors and Quads. The problem is that the speaker does not run according to the rules that a lot of box speakers use- it seems to work best with amplifiers that can make constant power regardless of load- which is usually a tube amp.
Many transistor amps will double power as you cut the load impedance in half. The Quad has high impedances in the bass and low impedances in the treble/HF region. Most transistor amps will play the speaker with weak bass and too much highs.
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