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I was thrilled to find a pair of used electrostats ( Martin Logan Quest Z speakers ca. 1993) I could afford and brought them home with great anticipation. However, when I set them up (jumpers between the two speaker terminals) with one amplifier, though the treble was great, the bass was so subdued as to be practically not there at all. (My amps are Cary 70 watt per channel monoblocks)So I hooked up my Dynaco ST-70 to the woofer leads and biamplified. Now the bass was heavy, tubby, chesty, extremely obtrusive and unbalanced. It sounded like a cheap subwoofer. I couldn't stand it.
My dealer suggested the problem might be fixed by using a solid state amp which has a volume control and carefully balancing the degree of bass until it blends smoothly with the treble panels.
Has anyone ever tried this? Is it likely to work?
The dealer will allow me to return the speakers for full refund and I can go back to my Audio Physic Sparks which are an extremely well balanced speaker. They do nothing gloriously, but everything well.
Follow Ups:
I was just having the same type of problem with my Mirage M3si. I was lent a smaller solid state pwr amp for a few weeks (my own amp is OOC) and the amp has only one set of speaker posts per side. I usually use dual runs of Straightwire Maestro II, but the amp terminals would not hold both sets. So I had to use my home theater single run of Analysis Plus Oval 12 with matching Oval 12 jumpers. By the way, I run the speaker cable to the mid/high speaker terminal and use the jumpers to the low input.The sound, though nice and pretty smooth, was disjointed. The bass was predictably less controlled, but was also way too heavy or thick and way off from the mids and treble. I replaced the sigle run Oval 12 with a single run of Maestro and it was quite a bit better. However the bass, while cleaner and better defined than before, was still somewhat disjointed, sounding like it was coming from different speakers or something. I replaced the Oval 12 jumpers (going to the low input) with the original stock jumpers that came with the speakers. While this is not ideal (lacking bass power and definition), the sound is now cohesive and balanced.
In other words, the speaker wires and jumpers have a profound effect upon the proper integration of the woofer into the overall sonic fabric from the speakers, at least in my system.
I have an earlier pair of Quests (circa 1992). I tried a number of different 100 watt solid state amps that just did not work. Even a pair of good quality (museatex) 100 watt stereo amps that were used via bi-amping. I eventually got a pair of bryston 7bst monoblocks and suddely they really worked. Now, my room for these speakers is huge and with major volume and loud peaks the protection circuitry is occasionally tripped, but the speakers are fine in a minute or so.The deal suggestion may work, but the dyna was never a great low end amp. There are a lot of very nice older amps (forte, mc, ps audio, etc. etc.) that can be had for A couple of hundred bucks that could handle the woofer. AN older pair of bryston 4bst could be excellent.
The speakers can really sing, but lots of power is critical. In all honesty, I am surprised that your amp does the panels well. My problem was always with the panels, not the woofer.
to make them sing properly. I am driving mine with an ARC D-250 (250 w/c) tube power amp with a lot of power to spare. If you want to passively bi-amp them make sure that the two power amps that you are using have their own attenuation so that you can match the gain between the panels and the sub-woofer properly and seamlessly.I have tried the passive bi-amping route with them a while back using the Hafler P-500 (500 w/c) on the bottom end and the ARC D-250 driving the panels. The sound was fast together with excellent dynamics to say the least. However, the sound on the bottom was a little dry for my taste as the bloom on the midbass was missing. Therefore, I went back to my old configuration using only the ARC D-250 driving them.
BTW, if you can find a vintage Sansui BA 5000 power amp is a good match with them as well. I have auditioned it about a couple of months ago. The sound was almost as good as my ARC D-250 in the midrange coupled with an excellent pitch definition on the bottom end much better than the Krell KSA 250 that I have tried a while back.
Were you ever satisfied with the sound? Did it produce a pleasing match or are you still aware of a bass/ treble disconnect?My dealer suggests that an inexpensive SS stae amp with attenuation should work fine. I'm not so sure but will try it. If it takes such expensive gear to achieve good function, I'll just return the speakers.
As far as I am concerned one of the reasons, why you have heard the lacking of cohessiveness between the panel and the subwoofer is you are under powering them. I have heard this anomaly before when I was using the Adcom GFA 555 (200 w/c) power amp to drive them. You would think that 200 w/c was enough to make them sing properly I was wrong as the Adcom didn’t have enough current to fully control the bottom end.BTW, Martin Logans speakers are very transparent so if you feed them with garbage, garbage you get.
Hybrids: the promised land
The obvious promise of a hybrid loudspeaker is that it combines the best of two worlds—the bass extension and punch of a dynamic speaker with the midrange transparency, speed, and detailing of an electrostatic panel. However, the hidden promise is a speaker that does much more. For example, a full-range ESL suffers from poor sensitivity due to the need to space the stators far enough apart to allow the diaphragm sufficient excursion to reproduce bass frequencies at high levels. The size of the panel also escalates to intimidating proportions to maintain decent bass extension in the face of dipole or front-to-back cancellation in the lower octaves. Relieving the panels of responsibility for reproducing bass frequencies allows the designer to optimize the design for greater sensitivity. It also makes it possible to use a curved diaphragm for increased high-frequency dispersion.However, there are three basic problems standing in the way of a successful integration of two disparate technologies.
The first has to do with driver "speed." The common (mis)conception is that a dynamic driver isn't fast enough to keep up with an electrostatic panel, the overall presentation lacking cohesiveness. The disparity in speed constantly calls attention to itself, giving the impression of a sea of upper-range detail emerging from a sluggish low-frequency foundation.
Such a picture, while useful for a taste or flavor of the problem, is technically misleading. Dynamic woofers have received a bum rap in audiophile circles. There is no reason that a cone woofer's acceleration or risetime could not equal that of a lightweight diaphragm. It's a question of force over mass—as Newton discovered three centuries back—and ML proudly makes mention of its woofer's risetime in its literature. But this is all a red herring. Woofers don't need speed. Yes, Virginia, tweeters do, but, most emphatically, woofers don't. Spending their time in the basement, as it were, reproducing a bandwidth limited to just the first several hundred hertz or so, woofers don't require large accelerations.
(Dick Olsher, October, 1993)
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