Help mismatch maybe?


Hello folks,

I recently purchased a pair of Quad 21L2's here on Agon. I tried them with some older Adcom electronics, which were uninvolving. Having read alot of good things about Nad products, and since they were in my price range, I purchased a C372 Intergraded amp here on Agon. The sound of the Nad and Quads are very detailed which I like more then less. Although, I would like the sound to be a little fuller & organic in the midrange. As it stands right now, the system sounds as though the treble control is almost maxed and the bass control is half way on the minus side. (I am in tone defeat mode).
My wife who is also my listening buddy, finds the setup too bright for her ears, and she is unable to listen with me now, unless the volume is very low. Our listening tastes in music range from Classical, to Classic Rock to Jazz, to Female/Male vocals, and everything in between.

Our front end consist of a Arcam FMJ CD23. IC's are of the Monster, and Z squared varity. PC's are PS and Z squared types. SC's Monster M2's Speakers are on the long wall in a Near Field configuration far away from the side walls and at least 3 feet from the rear. I have tried various placement scenario's and the NF seems to be the best overall.

Now, Is it possible That the Nad and the Quads are a mismatch?
If so, I would like to keep the Quads. If it's the electronics, I would like to stay with a Intergrated amp.
Are there any simular experiences, or recommendations you could offer?

Any help along these lines would be appreciated.
Thanks.
mickey13

Showing 4 responses by atmasphere

You have a mismatch. The speakers are a Power Paradigm device (they expect constant power from the amplifier, regardless of load), and your amplifiers so far are Voltage Paradigm (they make constant voltage regardless of load). Anytime you mix the two a tonal aberration is created; in this case your description is exactly how this combination will act. For more information see:

http://www.atma-sphere.com/papers/paradigm_paper2.html
Mapman, the short answer is no.

All you have to do is look at the designer's intent, particularly with the speaker designer. What is the amp that he is using in the design process? Is it tubed? If so, its likely that he has engineered the speaker to work properly without the ability for the amp to double power as the impedance is cut in half.

OTOH, look at a B&W 802. There is not a tube amp in the world that will play bass right on that speaker- you need transistors, as the woofers are running at 3 db less efficiency as the midrange and tweeters are. You need an amp that will double power when it encounters the 4 ohm woofer load, while the rest of the speaker is 8 ohms. That makes the woofers play at the same level as the rest of the system.

In the case of all planar speakers, they must be at least 5 feet from the wall for proper response, otherwise you will not realize everything they have to offer. If people are getting good bass out of Quads with a transistor amplifier, nice times out of ten I find that the speaker is fairly close to the wall too. This causes a bass enhancement at certain frequencies, wherein the backwave is able to reinforce the diaphragm, but it results also in a 'one-note bass' sort of like a boom-car.
Mapman, that could be- sort of. The problem is that ESLs in general do not have an impedance curve based on box or free air resonance. It is based loosely on a capacitance. Consequently, it will require constant power with respect to impedance, not constant voltage.

Unfortunately, but like many deisgners, Quad has chosen to try to make their products operate under the Voltage Paradigm rules, but if you have spent a lot of time with Quads, you know that they have had only limited success (don't believe me? -look at all the original 57s, 63s in service and they even went so far as to reproduce the 57...) with that route.

Martin Logan has been following that route for years (trying to get a Power Paradigm technology to work with Voltage Paradigm amplifiers) and you see similar issues: it takes the right kind of amp to really make the speaker sound like real music. Yes, you can drive them (the impedances are quite low, thus favoring transistors in a way) but its really really hard to get them to not be bright and otherwise sound natural. That's what I mean by 'tonal aberration'.

Its a fact that all amplifiers (transistor, tube and class D) sound better when driving higher impedances. So its important to understand that the differences between VP rules and PP rules are not about the total impedance, and more about the behavior of the relationship between the amp and speaker. Nor is it about tube vs SS, although that debate is better understood if you know the differences between the paradigms, which in fact is what that debate is all about (as is objectivist vs subjectivist).

The bottom line is that even though ML and Quad have been taking a similar path, both would benefit by increasing impedance, if nothing else.

BTW, a set of ZEROs (http://www.zeroimpedance.com) will often allow a tube amp to easily drive either load.
Mapman, ya learn something new every day. I would not have thought that Quad would do something like that... from the looks of it, with the woofers in parallel and Quad's tendency in the last 20 years to use transistors, my bet is that these speakers are Voltage Paradigm devices- doing what they could not do with ESLs (although I am sure the ESLs have higher resolution...).