Bringing the QUAD 22 control unit back to use
- Tuesday, 25 May 2010 14:21
- Last Updated on Wednesday, 06 November 2013 21:08
- Written by Jeroen
While busy with the QUAD II power amplifiers, I decided it would be very nice to have a matching 22 controller unit with them. For a few months I watched local adds, hi-fi shops, and Ebay closely. After seen various examples passing by I took my chance on an example from the UK which I found on Ebay. Not the sweetest example but quite a bargain, and "still working" as the seller claimed ...of course it was not. Well, there was sound I have to give him that.
The QUAD 22 inside-bottom view after replacing all caps and all what was needed.After fixing a few dry joints and replacing the ECC83 amplifier tubes, there was a little bit more sound. But soon it started to thick and plop. Hoping that it was not a faulty C7,C12,C15 combination, I started to replace just everything that was out of spec or could possibly fail. You can see this on the picture on the right.
After that was done the amp sounded better, yet the plops did not fade. Talking with Manfred Stein from QUAD GmBH about it he had a spare replacement left from the adoption of QUAD machinery back in the late nineties. It was not cheap but had a nice fit with mounting clips and all, it solved the click-and-plop problem.
Most of the crackles on the controls and knobs were eliminated with some Kontakt-60, spraying gently inside the volume and tone controls. Still the sound did not strike me and I put the unit on the shelf as 'must have' but 'not useful'.
Along the way, after leaving it for months just on the bookshelf in front of me, I found it time to give it another go.
After powering up, most of the crackles were back (of course...).
Also a suitable CD input would be nice - I mean, what use is it if it can not handle my most used program materials? And so I made a special attenuated cable following a scheme I found on QUAD-World. Now the CD-player could be connected to the tape-replay without needing the tape adapter - which was not up for the job anyway.
Oddly the tape input is somewhat on the end of the switching board, depending on other contacts and one of the weakest constructions on the QUAD 22 are the switches. So, it plays nicely one day - it fails the other - and you never know when or which channel. Adding to that the balance pot started to fail causing the sound quality to drop even further.
Some call the QUAD 22 'nice' but a bit 'out-dated'. Yes indeed, the standard QUAD 22 is; and so it lived on the bookshelf in front of me - chewing on me some more. What good is this control unit if I can only look at it? Yes it works but its quality is nowhere near the QUAD II power amps.
Although my intension is always to keep things as close to original as possible, it was clearly not ging to work with the QUAD 22. Not as long as you want the most out of it, like me. I am used to the sound of newly revised QUAD 33/303 and considering the quality of the QUAD II power amplifiers, it should come close, at least.
After gathering more information about this subject on the internet, I decided to write an email to Keith Snook at www.keith-snook.info about cleaning and alternative volume and balance controls. He came back to me directly with the advice to first try to dismantle the original pots and if still right, clean them or fix them. Along with this he promply updated his website with the original QUAD balance modification intructions. He also found a spare volume pot, in case I needed it - but urged me first to try fix my own (try finding such a salesman nowdays that gives support over sales!). To bad I forgot to make photo's of the complete inside but I only have the one you see above - which is the inside of the on/off switch on the back of the volume pots. If you look closely you can see the two contacts are fixed with expoxy resin (tip from Keith again). After cleaning the pots gently with paper and some alchohol i put it back together - it has been working marvelously for over a year now.
Time to clean switchboard. But how? All these wires made me nervous when I looked at them. Would I ever get them back in place correctly, I asked myself. All those rather confusing paths to and from the pickup and tape adapters. I wanted to have a correct RIAA stage for my pickup too. I had fixed this around the female plug from the pickup adapter inside the QUAD 22 already - but never found the exact capacitor values - and so the pickup was still no option.
Most users probably only use the radio, tape and pickup inputs with the original adapters, which are not really up for the job nowadays. Looking over the various options Keith offers on his website, I found it was worth trying out his QUAD-22-Switching-C.pdf option, which turns the tape-input into a direct switched CD-input, and the tape-output into another CD-input while leaving the radio1 inputs intact, and turn mic+radio1 into another 100k? input. On top of this, I could add Keith's RIAA PCB to accommodate a 'correct' RIAA input for my pickup. Making a total of five inputs but no outputs.
On the right you see the stripped down QUAD 22. Switchboard and RIAA section removed. Also note the gold plated inputs, using the existing holes. No drilling needed - keeping just everything restoreable.
At first I was a bit worried if I would ever be able to get this back together - but along the way stripping down - I found it was actually getting simpler. The most confusing part of this amp is the complex switching along with adapter configurations. Removing those options leaves you with the bare amplifier on the bottom side - and the tone controls on the top side.
When the switchboard was disconnected, I removed all old solder with a pump and de-solder wire. Then removed the dirt left on the joints with alchohol.
After that I removed the springs and dipped the whole thing (not the knobs) in a pot with hot water, washing-soda and some aluminium foil, leaving it for 30 minutes or so.
This cleaned most dirt pretty well but not enough for me, so I removed all contact PCB's from the switch and carefully polished them with Brasso, metal polish. I polished the contact-forks that were left on the switch with a soft brush, cotton and Brasso. Then fixed the whole thing with a few drops of epoxy resin on each contact board and greased the switches with a tiny bit of pure petroleum jelly. See the picture above.
For the cinch connectors I found a model at Conrad Electronic that fits just into the holes left when you remove the original connector boards. Fitting them on a blank PCB inside and secure the whole lot with four bolds where the rivets had been before.
The RIAA PCB is made of quality components, and has new ceramic tubes bases. It fits perfectly on the bottom plate of the QUAD 22 so the EF86's stay in place. Inputs are directly wired from the pickup input connectors and the output directly onto the switchboard. The other connections are for heaters and HT, very easy.
Soldering the wires back on the switchboard is more difficult on the top-side as there is little space left (if you like to wire it up nicely) . (left)
The bottom side is fairly easy to rewire. The switching-C scheme also covers the stereo-mono switches, making it work just like original.
The moment of truth - testing
After double checking all connection paths, the moment of testing was here. I first did a dry run without anything connected - everything appeared to be all fine. Time to connect sources and speakers. It all worked as should. Time for some real testing - wire up the ESL '63s, sit down and be amazed!
Starting off with 'Españoletas' a Ruiz de Ribayaz improvisation - which was last on when I was finishing up the controller - a good piece to begin with! See www.alpha-prod.com. This CD is both extraordinarily musical as well as a recording art-work. It was amazing to hear so much music now instead of just 'sound' or even 'good sound'.
I personally do not like the 'how it sounded better' reviews. Everything always sound better then before and may the most impressive (read "expensive") piece win. But yes, the lower bass, clearness and imaging and all of those are really good. It probably makes more sense to tell what I am used to and if this was as good or better.
I mostly use a revised QUAD 33 with two mono 303 amps along with two up-to-spec ESL '63s. As source I mostly use my good old Rotel RCD 970bx, a FM3 or FM4 and a standard Thorens TD125 mkII with Denon DL-160 cartridge. The QUAD 33 is adjusted somewhat to my liking and I, therefor, prefer it above a QUAD 34 I had before. The sound of the valve combination sounds very much like this but seems a little bit more open and smoother. Probably tubbish :-) The pickup input is a little soft because of my low output cartridge but sounds by far the best of all i have tried on the QUAD 33 and 34 - and makes it well worth building this into the QUAD 22 controller unit.
The pictures below show how it looks now.
Tone controls upgraded with 1% extended foil polystyrene caps.
Sprayed the same as the power amplifiers.