Return of Quad 22 preamp
There is no doubt that I'm a passionate Quad lover. I've been since the beginning of the century when I acquired my first set of Quad 22 preamp and Quad II mono blocks. Soon after the amps I also got hold of the ESL-57s to go with them. Today I have three whole sets.
One is downstairs in the living room where the family is watching TV. That system is not in frequent use for obvious reasons. The second set stays upstairs, and is incessantly used, especially during the weekends. The third one, also fully functional, is an auxiliary one.
The set upstairs has three turntables to choose from: EMT 927 with EMT 139ST preamp, SME 30 or EMT 930. The cartridge is the classic EMT TSD-15, and here I go against many. I like the basic TSD-15 Spherical more than Koetsu Rosewood, VanDen Hull Gold coil modified Rosewood, Clearaudio Accurate, and even more than TSD-15 SFL (super fine line).
From the EMT 927 - the main turntable in charge - the signal travels to the input (Radio) of the Quad 22, and from there to the Quad IIs, and finally to ESL 57s standing on top of Gradient SW-57 dipole subs. For the highest frequencies I've added a Fountek Ribbon tweeter shooting to the ceiling. There is no crossover except a simple high-pass filter for the tweeter. Three speaker cables come out from the Quad monos: one to ESL, another to the sub and from there to the tweeter.
A very cool point about the Quad II's is that one can run them with no speakers connected. No need to worry about impedances or anyway less than with many other power amps. In my system that property is much appreciated since the Gradient subs are driven without the Gradient active crossover, just parallel to the ESLs. The two 10 inch woofers in the Gradient subs are also connected in parallel. I haven't calculated what the actual load impedance is, but with the Quad IIs this setup is possible.
Over the years I've looked into the innards of the Quads quite often. In this I've got valuable help from Keith Snook personally and also from his excellent website
http://www.keith-snook.info/QUAD-stuff.html
As a result, I've changed certain resistors and capacitors, and so on.
In listening to the Quads, one striking observation has been how good the Quad 22 can sound despite the fact many of the capacitors and resistors often have quite drifted values. This in mind, and while fixing a Quad 22 preamp for a friend, it occured to me how would the Quad 22 work and perform with no negative feedback? To the best of my knowledge, hardly anybody has tried it.
After delivering the modified Quad 22 to the happy owner - happy since the 22 can sound outstandingly good when all components are according to the original specs - I took another 22 on a table to work with, and to check how it would perform without negative feedback. I soon found the NF loop and disconnected the Capacitor C10 & C11 in order to cut off the loop.
Then I simply listened to the resulting sound. Remember, I'm not a technician. I'm just curious about these amps and if I don't understand something, I ask help from others who know. There was a lot of hum and noice, but the music behind sounded fine to my ears. That was just what I needed. A fast and powerful sound, even if a bit aggressive.
The next step was to consult my knowledgeable friends. I have two to thank for especially. Miikka is there for my basic stupid questions, to which he's always willing to answer. The other is Vesa, an electric engineer and the actual designer of the no-NF 22 preamp, with whom I frequently talked to and changed emails before we got the project into a working stage.
Vesa found a basic schematic from the internet. The schema was sufficiently close to the line stage circuitry of the Quad 22. I started to solder the new preamp according to the new schematic. The sound wasn't that great, but it had the potential. We then started to rework and finetune the schema. It took several weeks. At the moment I am so pleased with the sound quality that I am afraid to proceed any further.
I also disabled all the possible tone adjustments. I had always used the Quad's ingenuous cancel (direct) position (bypassing all tone controls). Now that we went for a straighter sound it was natural to get rid of all the tone controls completely.
I also disconnected the channel balance to keep the signal path as clean as possible. Every true owner of the Quad 22 preamp knows that the volume pot of the 22 is a kind of balance control in itself. That is, the balance can be directed a bit to left or right by turning the pot.
I have always believed in the "less is more" principle in electronics. The Quad 22 is a remarkable example of the principle. At first sight, the 22 may look messy from inside but actually the circuitry is minimalistic.
Simplicity is one reason why I also respect the RIAA section of the Quad 22. The whole RIAA is realized with one EF86, a few capacitors and resistors per channel. Having eliminated the NF from the line stage, the next step was to correct the drifted capacitor/resistor values of the RIAA stage. I've failed to see a single Quad 22 in which the values would have been correct. For example, the value for the C1 & C2 should be 5000p but in all individuals that I've looked into the value's been double or more: hardly beneficial to the RIAA calculation. Invalid component values must be one of the reasons why the 22 has got the bad reputation that it has had. Very unfair. In fact it's a kind of miracle that they sound so good given that most of them are so out of specs.
I normally use the EMT 139ST as a phono stage. The same Haufe MC transformers as in the EMT 139ST are to be found also in JPVanVliet's Tonearm-Interface-Box. The transformers sound so good that I now take signal straight from the JPVanVliet transformers to the Quad 22's RIAA. I'm enthused about the sound so much that I have agreed with JPVanVliet to sell his transformers in Finland (the same price as from VanVliet) in order to give people a chance to try them. More detailed info here:
http://www.jpvanvliet.nl/TIB.html
My system is now this: EMT 927, JPVanVliet StepUp transformer, Quad 22 preamp. When a MC cartridge is used, a quality stepup transformer is a must with the Quad RIAA, which was originally developed for a 4mV moving magnet cartridge in mind. I have tried Denon AU-300LC/1:10, and it was OK. Denon AU-320 was better. Bent Audio Copper 1:20 was better still but the JPVanVliet Haufe 1:40 the best. The last one may be the best match for the Quad 22's 68K input also: it likes to have power in the input.
As far as I'm concerned, sonically the new Quad 22 SE was a big success. The sound is very dynamic, open, natural. Instuments sound, more than before, like themselves. The sound is rolling and lively. In comparison, the 22 with negative feedback (but with right component values) sounds a bit too nice, too comfortable. Sometimes when switching back and forth I may still feel that the difference isn't that big. Then the best thing to do is to play the two versions for a while with all possible music material, and compare. I'd say that the SE version has more of everything.
There are some drawbacks too and I might get back to them later.
To crosscheck my findings I will next send the two versions, with and without NF, together with the JPVanVliet stepup transformer and the Quad II monos to other people with good ears and relevant experience of tube preamps and amps. Kari Nevalainen's second opinion is presented below.
My friend Marko, who has owned a refurbished Quad 22 for a long time, compared his unit with the Quad 22 SE, and now wants the latter for himself too. This is good news because over the years I've learned to trust Marko's judgement in these matters.
Quad 22 SE Signature
The new Quad 22 SE in my system, I started to entertain the idea of making a "super" version of it, ie. otherwise the same unit but with the best components that I could find easily. I had already used carbon film resistors which to my ears are the best: as a rule I don't trust metal film resistors, and carbon film is more stable than carbon composition, - and sounds at least as good.
As for caps, I ordered the Auricaps: they were easily available and raved by many modifiers. Once the caps arrived, I immediately replaced the old Icel caps with them, and holy cow!, the sound was a way better in many respects, so much so that one could consider it as a totally different preamplifier.
It will now be super exciting to test the three amplifiers side by side: the basic Quad 22 with reset specs, the Quad 22 SE with no NF, and finally the Quad 22 SE Signature with no NF and new caps. Quickly evaluated, I'd say that if the basic version sounds better than expected, and the SE version sounds better still: more energetic and faster; the best version is the SE Signature with by far the best bass performance.
It is curious that when a preamplifier's sound gets better and better, I hear the improvement most easily in the bass. Not only is there more and deeper bass but its quality is also better, less muddy, less round. This finding lends support to the often made claim that amplifiers and speakers equipped with Auricaps have more bass.
Since the only difference between the SE and the SE Signature is the capacitors, the change in the sound quality, if any, must be caused by them. To me the magnitude of the difference between ordinary and excellent caps was something that I couldn't imagine beforehand. Amazing. I'm now waiting to get more Auricaps to make more Signatures. Perhaps I should try some other quality caps too ...
Second opinion: Kari Nevalainen
At some point of my audiophile career I've owned a Quad 22/Quad II combo myself. It wasn't at all like this combo under review. The Quad 22 was in pretty bad condition, mainly useless. My Quad II monos were not powered via the Quad 22 preamp as in this case but had new a PS. Nevertheless I liked the Quad II monos driving my Quad ESL57s (with and without a DIY dipole sub), and the Decca/Kelly Ribbon tweeter. With certain music/recording the 50 year old system was unbeatable, and I think, still would be.
But none of my memories of my Quads could prepare me for the big surprise that I experienced when I first swicthed on Ilkka's Quad 22/Quad II combo (the speakers were Penaudio's new Cenya). A very, very competent sound. My nearest reference was my heavily modified Dynakit PAS-III preamp with a 6V6 PP power amp made solely of vintage components. The Quad 22/Quad II combo sounded more dynamic, more transparent, more like a true highend tube gear (the input tubes of my power amp are almost useless, and its suffers from an audible 100Hz AC noise, but still).
And this was just the basic version reset to the original values. The no-NF version sounded, not necessarily more dynamic (both pres had a good sense of power), but a tad more transparent with a more developed soundstage. The edge between the two versions was there but it was partly overshadowed by the general level of sound quality of both preamps when played with the Quad II monos. But it will certainly be interesting to audition the super version, SE Signature. And when I do I will also put my pen and ear on the Quad 22's RIAA-stage fed by JPVanVliet StepUp transformer.