The Redmere Soloist

...a hard to find heavyweight from the seventies

1) General

 

This page started in September 2010 when I was going through some old drawings from years back and this unusual amp turned up. I've never seen another copy of the schematics and, although we're talking late seventies not sixties here, I thought it deserved a look. Just out of interest, PA:CE's workshop was just at the other end of our road at one time.

If anyone read this page a few years ago, the drawings were obviously early development versions. They've since been replaced by details taken from a strip down of genuine production units.

The Soloists were available as separate head units or combos, both built into flightcases. The combo weighed about half a ton and it certainly wasn't car or shin friendly. On the other hand it was a brave attempt to offer a huge range of sounds in one box and probably deserved to sell better than it did. There's a very interesting article by designer Tony Reeves in the Summer 78 issue of MM Musician magazine which documents the development process from 1977 prototypes up to the 1978 production launch.

Estimates for production numbers vary from ten (definitely not right) upwards but, until someone who was there at the time helps out, these are just wild guesses. I've come across at least ten in the UK, one in Belgium, one in Holland and four in the USA. The highest serial number I've actually seen is 51056 (dated Feb 1979) and Dennis Burns has number 50046. If the 50000 and 51000 series are separate runs (51013 exists) then we're up over a hundred. Gary Dobbins of Crosstown Studios in Boston (USA not Lincs) had three of them....

Dec 2012 from Gary...I had a recording studio and small instrument store in Boston in the late 70's. I bought the first three Redmere's that were sold in the US. I sold the first two and still have the last....We had a problem with the second one and had a repair person rebuild the unit putting in Sockets for the chips to allow easy replacement and they strengthened all the rails to the circuit boards....We created a tape of the Redmere sounds for a Music convention in Boston in 79". A guy named Jack Morgan played and discussed the different sounds......The amp still works (I just had some repairs recently (new caps etc.)....The amps listed for $2,600.

Having looked at a unit dated 1979, there are obvious signs of cost cutting and a general lowering of the build standards between this and earlier examples. The Molex plug-in connectors are gone and the loom is soldered straight onto the board headers (still the mating Molex parts funnily enough). That's a shame because it makes it a pig to repair. On the other hand I've spent hours tracking down a very intermittent loss of volume that turned out to be a corroded connector on the power board. Be very careful unsoldering the touch switches, you'll never find another one.

There are anomalies in the serial numbers too. They seem to fall into three groups, 50000 series, 51000 series and a lot with no serial number at all. The labels were only stuck onto the back panel, but they shouldn't have fallen off without leaving some trace and it's hard to believe that so many amps were stolen and disguised.

One thing to ignore if your thinking of buying one of these is "used to belong to (insert name of famous musician)". It usually isn't true and, even if it is, the leftover DNA on the knobs won't help you play any better. Just go by price and condition. There are some clean examples about, but anything stored in the damp will be suffering from corrosion issues by now and a proper service will mean a complete strip down and several hundred pounds in parts and labour (that's if you can find somebody daft enough to do it). I've just rebuilt one that's been stored in the damp for ten years or so and it's been nothing but expense and headaches.

Original parts will be difficult to find and expensive. Most of the caps, for instance, are Mullard C280 series tropical fish and the ends of the casings will have started to fall off. The Egen pots and sliders aren't made any more either and their exact size is important to mount the boards in the right position.

Asking prices seem to range from 'free to a good home' (always welcome, but beware unless your very rich or know what your doing) to silly money for immaculate examples. Bear in mind that, while they're a lot of fun, they are extremely large, too heavy for one person to lift and won't fit into the average car. The very complicated (and irreplaceable) footswitch is also needed to make the most of the channel switching facilities and it's normally missing.

Apart from all that, they are a lot of fun and if you have a few hundred pounds to spare, don't have back problems, you own a studio or you have a large house and a very understanding wife, go for it.

 

Feb 2016. There's probably enough feedback from owners now to start another page covering Soloists actually in use for anyone who's never used or heard one. It might take a while to put it together but use this link or the one at the top of the page to see how it's getting on.

Please use the information as a starting point and watch out for mistakes (by me) and variations in your own unit.

The power amp schematic below is for a later version and very early units are different (see section 16). It's quite possible that there are several versions of all of the boards.

On production models, the low voltage supply will be  +/-12v not +/-15v as shown on some of the earlier drawings

Finally, Apologies to anyone who actually worked at PA:CE and knows what they're talking about (I didn't and don't), but this is all we've got to keep these old things on the road for the time being.

2) Nov 2010 

 

Thanks Steve for sending in pictures of this immaculate and virtually un-used thirty year old. The serial number is 51013.

(Sorry Steve I've lost your details. If you get in touch I'll give you a proper acknowledgement.)

 

3) Dec 2012

 

Thanks to Huub Dirks in the Netherlands for these pictures of his amp. The Pye electrolytic has a date code, 7827, which we're guessing is week 27 in 1978. Unfortunately I don't have the serial number. Incidentally, all of the Pye caps in production Soloists are probably from some time in 1978. 

 

4) Dec 2015

 

Thanks to Dennis Burns for a huge amount of help with circuit details and photographs. He came up with this Redmere pamphlet that has models I've never heard of let alone seen. Tony Reeves, writing in MM Musician magazine, says that a simplified version was exhibited at the 1977 Frankfurt Trade Show so these may be the early prototypes.

5) Dec 2015

 

Thanks very much to Graham Smith for these photographs of what must be the world's most expensive footswitch . Graham's combo came out of the factory in 1979 and has a slightly different flight case construction to the others you see here. The three banks of slide switches set up the effects on each of the footswitch selections.

 

From left to right

SW1. V1 (presumably Voice or Channel 1)

SW2. V2 (presumably Voice or Channel 2)

SW3. V3 (presumably Voice or Channel 1)

SW4. REV (Reverb)

SW5. C/SUS (probably Compressor/Sustain)

SW6. FLANGE

SW7. CHS (Chorus)

 

You can allocate each footswitch on the top panel to any, or all, of the three input channels and set up different effects for each selection (they could all be the same channel with different effects). The large numbers on the back refer to the footswitches, not channels.

Interesting account of using two switches at once here.

6) What does it do?

Although PA:CE never specifically named the amps that the Soloist was modelled on, there are some heavy hints in the publicity claims.

These quotes are taken from the "MM Musician and Redmere Amplification" magazine of summer 1978;

  • 'Channel 1 of the Soloist simulates a familiar American valve amp usually bought in the "twin reverb" form.'
    We'll take that to be a Fender Twin Reverb without the capital letters. 

  • 'The second channel gives you the sound of the top British rock valve amp used by practically any big rock band you can think of. ....This sound is clean up until 25 watts and then distorts more and more. Once you reach a certain volume, the sound changes and distorts dramatically to give a familiar raunchy blues sound that you'll recognise as soon as you here it.'
    That's got to be a Marshall of some sort.

  • 'If you were a fan of The Beatles...you'll be familiar with the 30-watt combos they used. The Redmere Soloist gives you the sound of the Sixties Beat Boom with channel three.'
    Vox AC30 for channel three then.

With no mention of any particular year or version, these references are still difficult to tie down and, with the greatest respect to the designers, it's probably best to judge this amp on it's own merits.

7) Signal Path Overview

  • Note how much of the processing and mixing is done on the Channel 1 circuit board. For instance, Ch2 and CH3 can both stop working if the FX Send Mix circuit (on Ch1 pcb) dies, leaving Ch1 to carry on as normal.
     

  • Touch switch circuits are cheap and cheerful and not particularly reliable. Clean the metal pads with a small amount of Isopropyl Alcohol (IPA) on a cloth. If they still don't work just rest your hand against the front panel aluminium trim while you touch them (or take off your shoes or open a window - whatever works at the time).
     

  • Although most of the effects can be bypassed with the touch switches, the Graphic Equaliser is always in circuit so it can be a show stopper. Very difficult to access as well. Other problems include corrosion on the Molex connectors on the wiring loom and dirt in the Aux input and Stereo Chorus jacks. The Stereo Chorus jack allows the Chorus effect to be routed to a different amplifier or mixer channel. With no plug inserted, the shorting contact routes the effect back into the main amp so it needs to be clean. Similar story with the Aux input.
     

  • The CH3 FET switch on the power board is part of the AC30 (reportedly) emulation circuit and changes the feedback characteristics. It also increases the gain slightly if you select Channel 3 while using the Aux input to test the output stage (one way to see if it's working).
     

  • The power amplifier uses current sensing feedback, so it's important not to ground the negative speaker terminal. Scopes and other test equipment shouldn't be connected directly across the speaker/dummy load unless they're battery powered or have a ground lift facility. Checking the output with the scope grounded to the chassis is close enough for Country.
     

  • Chorus, Flanger and Sustain effects aren't the quietest things in the world so they're all designed to activate the Noise Gate when they're selected. If you're playing at low level this can cause really annoying signal dropout unless the gate control is set fully anti-clockwise.

8) Mechanical Parts

Most of the faults that turn up these days will be down to old age and misuse, particularly on earlier chassis that use plug and socket connections for the wiring loom. These are really useful for service work but a bugger for noise and open circuits when they corrode. On a later unit inspected the looms were soldered directly to the boards except for the footswitch wiring.

Spare mechanical parts are very difficult to find, the push-on control knobs on the earlier versions being a particular pain. There are two different types on the panel. They look identical, but the flats on the vertical effects boards are in a different place to those on the horizontal channel boards (that probably only makes sense if you've seen one). Neither are available but you can still buy the grub screw type used on later units. These can be adjusted to fit all positions.

The drop down rear panel is fitted with a coffin lock (honest). You can buy a fairly close replacement and a key from Penn Elcom. 

The butterfly catches are also odd. Unusually, they have the butterfly on the removable lid section. That's a good idea to avoid rattles, but they appear to be specially made to fit into the limited width available. Good luck finding a replacement.

Before diving in to fault find, it's worth spending some time looking through the overview drawings and studying the signal paths. They aren't complicated but they're interlinked with the switching logic and each other.

 

Circuit boards have identification codes in the track side artwork, typically 'S - n - 1'  'S - n - 2' or 'S - n - 3'  where S = Soloist, n = the board number and 1, 2 or 3 is the board issue number. Later boards also have what might be a stock number '005 00nn'.

There seem to be three types of chassis serial numbers: a 50000 series, a 51000 series (I've got 51056) and a surprising number of chassis with no serial number at all (I've got one of those as well). Make your own mind up how amps with no serial plates got into the system. Somebody must know how many were made but they're not saying, so it will probably stay a mystery. It was certainly a lot more than the ten that you'll read about on the internet (but then the internet is full of misinformation happily repeated as fact in forums and for sale ads - quick rant there).

Heads up about a few problems:

  • Don't use the two mounting screws on issue 1 power boards for a scope ground, they're connected to the output transistor collectors. Use the chassis as a ground.

  • Don't ground the speaker negative terminal, it will short out the current feedback resistor.

  • Be careful moving the flight case with the front cover attached. The whole thing is very unstable and likes to fall over forwards. For the same reason, don't stack other equipment on top.

  • Don't buy one of these if you've got a bad back.

9) Tooling

Some of the board connectors are obsolete now but the table below shows the modern alternatives. The pins on the board headers are now round instead of square.

10) Drawings List

 

Click on the links below to open the drawings in a separate page.

© 2015 by backfromthesixties.co.uk