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Right now I’m out of stock of the 538.
I’m working very hard on the introduction of the new Alice 828 Mk3 so it’s unlikely that I will have any new stock of the 538 for a couple of months…… But it would certainly do the job that you talk about!
That’s a nice looking 828 Mk2 and if it ever gets back to ther UK, I should have a look at it and fix the problems….. Meter lighting was always seriously awful on those Sifam meters. Nowadays I take them apart and fit white LEDs.
I see that the last post was in January this year…. a lot has happened since then!
In co-operation with Paul Andersson, the present MD of Alice Ltd., I got my act together during the awful ‘lock-down’ and concentrated on a re-design of the old Alice 828 Mk1.
The result is that now it actually exists! There are a couple of videos on ‘you tube’, the second one is called ‘Alice 828 Mk3 Introduction’.
And here’s a few words about it.
Not necessarily. There were a number of variations and yours could possibly have been a ‘mono’ one.
However, the new 828Mk3 is now a reality, it has taken the whole of the ‘Covid’ period to develop, but it is now done and sounding the same as the original…. well, it should do; it’s using the same circuitry. The original needed a team of girls in the Windsor factory to do all the point-to-point wiring. The new one has clever precision circuit boards that eliminate all the channel wiring except the faders.
it’s sounding good…. and will be announced very soon!
No, that’s not right. The 828 range all have stereo monitoring with mono/dim switching but with mono PFL.
The new 828 Mk3 has the same but it also has a relay mute system so that the mixer is suitable for ‘self-op’ radio use.
BTW, the new 828 Mk3 is on final test now and will be announced shortly.
Here is the circuit diagram.
It would be possible to add an EQ in/out switch, but there may be problems with levels.
The top of the channel fader is fed by a 100uF cap. Switching the input of that from the output of the input amplifier should do the job, but I would advise against it because of probably unforseen level and stability problems.
If anyone asks me to carry out that mod, the answer would be no!
That’s a lovely very early one! But Yuk! Someone has drilled a hole right through my signature!!
But seriously, that model should compress wonderfully, that is the original SC2. There is certainly a problem.
With that model the most likely cause is faulty transistors in the compression drive circuit; there are 4 transistors and it is worthwhile to change them all.
If you need the circuit information for this model I can email it to you.
If you would like me to repair it and set it up correctly, then drop me an email at
The additional output gain control should not affect the compression in any way.
Yes, you are right, the new P38EX Mk2 is very nearly here…. in fact I have the electronics in production with 5 sets complete and tested today (30th Oct 2019).
That was the good news; the not so good news is that I don’t know of any tech people that I would recommend, Opto compressors are not particularly ‘advanced’ in circuitry, but they can be tricky to set up. If you want to trust it to a local tech, I am happy to let you have copies of the original circuit sketches and any other info I have; the info is a little scrappy, I never get the time to refine it! To get the info, please drop me an email on
If you want to send it back to me to sort out, that’s OK too.
A general note to anyone sending equipment to me to fix from the USA…… The equipment will not be working so be sure to mark it clearly as ‘NOT WORKING, RETURNING TO MANUFACTURER FOR SERVICE’. And on the customs forms put a very low value, otherwise I get interrogated by the customs here in the UK and end up having to argue for a couple of weeks and eventually having to pay full import duty. If it’s all kept ‘low key’, there is no problem; getting out from the UK is easy and trouble-free.
Keep an eye open for my new website….. it should be up in a couple of weeks; complete with pictures of the new super-smart P38EX Mk2 with its illuminated push-buttons!
I can’t be absolutely sure, but I would expect that this one has mic transformers which switch into circuit with the ‘Hi/Lo’ switch.
Note that it is fitted with PPMs so it must have been originally intended for a broadcast application.
That model (the 62/3) was the mixer model immediately before the introduction of the 828 Mk1 and the circuitry is very similar; the mic amp circuit (shown on this ‘subject’ in an earlier post) uses the same transformer as all the later 828s.
I would NOT recommend replacing capacitors unless they are faulty; as I have said often, capacitors have extremely long lives unless they are subjected to high temperatures. Old valve equipment often needed ‘recapping’, but I rarely come across faulty electrolytics in equipment that runs at normal room temperatures.
As for power supplies, I don’t want to get into recommendations. When I am repairing/updating equipment I often use Chinese manufactured switch-mode supplies but it’s not that simple; these supplies are reliable and efficient, but they often produce awful interference radiation that is not simple to deal with. If you are not experienced in dealing with power supplies generally, then be wary.
I believe the 62/3 mixer needs just a single 22 or 24V DC supply.
The very early ones, of which there were only a handful, were transformerless and I don’t have the circuit for that one.
The slightly later ones had a mic transformer and the switch just switched the transformer in and out.
Here’s the only circuit I have…..
The output control was simply a ganged pot inserted immediately before the balanced output stage. The pot had absolutely no influence on the sound of the compressor.
The ‘dark’ switch I introduced on the suggestion of an engineer in a London studio; he said that the later SC2 V2 sounded ‘lighter’ than the original V1.05 and 1.07, so I had a look at the timings around the release control and introduced a change that could switch in the exact characteristic of the earlier versions…. but the difference is extremely small and not noticeable on most music material. I have repeated the changes in the new TFPRO538 stereo compressor, this one also has a ‘dark’ switch. The main difference is an extended release time and a slightly ‘heavy’ effect.
But the main characteristic of the sound of all these compressors is the use of a batch of opto devices that I bought back in 1988. I still have a good quantity left and while I changed to a more modern (and much faster acting) type for the P38EX, I have gone back to the original opto device for all new compressors including the TFPRO538 and also the new P38EX Mk2 that will be ready in October or November this year (2019).
Compressors are extraordinarily complex things!!
😯 I will send what I have to your email address.
The MQ1 worked OK in some large format PCs, but the danger was always one of interference from the switching power supplies in the computer.
😥 Ha! That’s a very special VC3! We made just 2 or 3 of those painted yellow for a professional audio show in the US. That must have been in about 1981.
It’s probably worth a lot more than the original price!
The spec of the power supply is simply 12 volts AC. The supply should be capable of 300 milliamps or more, so any 12VAC supply will be OK.
I have a few of the first batch left now (22nd July 2019) and I can offer the standard BRICK2 at 25% professional discount, £690.62 (normal price £920.83).
There is the ECO version BRICK2 which is electronically identical but without the very expensive control knobs (but it still looks nice!) at £15% professional discount; £530.54 (normal price £624.17).
Those are the final complete prices with freight included for UK and EU.
My normal guarantees apply…. If there are any problems at all I fix it, no time limits!