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  • in reply to: Alice 62/3 mixer question #16195
    Ted Fletcher
    Keymaster

    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…..

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    in reply to: SC2 1.07 #16190
    Ted Fletcher
    Keymaster

    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!! 😯 :)

    in reply to: Joe Meek Mq1 Schematic #16193
    Ted Fletcher
    Keymaster

    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. 😥

    in reply to: VC3 PRO Channel #16191
    Ted Fletcher
    Keymaster

    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. :)

    in reply to: WHAT ABOUT THE BRICKS? #16150
    Ted Fletcher
    Keymaster

    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! 8-)

    in reply to: SC2 1.07 #16187
    Ted Fletcher
    Keymaster

    We only made the very early V1.05 with the bevelled front panel for a few months; it became obvious that the cost of the panel with its milled edges and the ‘coachwork’ paint finish were not really necessary….. the main thing was the sound!

    There was no difference between the design and performance of the 1.05 and the 1.07, I don’t clearly remember but the change was probably some small layout change on the PC board.

    The gain control on the back was put there because lots of users wanted an output control and I didn’t want to change the appearance of the front! In hindsight that was fairly dumb, but I still think appearance is important.

    Technically, the SC2 compressor adds to the compressed sound by dynamically adding harmonics during the time it takes to control the volume level. These changes are of extremely short duration and not noticeable, but have a profound effect on the ‘feel’ of the sound. Sounds complicated but in reality, it’s simple, the behaviour of the controlling electronics happens to emulate effects that our brains like; the ‘optical’ compression circuits are much nicer sounding than any other analogue compression circuit, and far superiour of course to any digital system no matter how carefully programmed!

    in reply to: R5 Burnt Out in P48 Circuit #16185
    Ted Fletcher
    Keymaster

    No, I have never seen this problem before.

    That power supply is normally, in fact always, reliable, so I can’t comment.

    Of course, it’s an old design, but it really has stood the test of time, so I suggest replace the parts and carry on using it! :)

    in reply to: The TFPRO 538 500 series #16180
    Ted Fletcher
    Keymaster

    IMPORTANT NOTE: The TFPRO538 is designed to fit 500 series racks that have ‘aux input’ and ‘aux output’ sockets; suitable racks are Bento 6S and Midas Legend L6 and L10. The TFPRO538 will not operate in stereo in the standard API or Neve rack due to lack of terminations.

    The situation today (9th April 2019) is that I have the first 6 production 538 units finished and tested, and up to 30 will be available by the end of next week.

    I’m going to offer these out on a ‘sale or return’ basis to serious engineers….. but please note my ‘important note’ above, otherwise it will only work as a mono unit!!

    Please feel free to contact me on [email protected]. :) :)

    in reply to: SC2 rev 1.05 not / hardly working #16183
    Ted Fletcher
    Keymaster

    Hi Daan, would you like to come back to me on email? It’s [email protected].

    The early SC2 compressors do tend to suffer from a problem in the LED drive circuit; I have known a few of them to go ‘soft’ and not compress as hard as when they were new. I do have a fix for that, it is to replace all the LED drive transistors, and sometimes even replace the opto cells….. I do have a stock of the original cells; I’m using them in my new 538 compressor. :)

    in reply to: Meeting Ted Fletcher and the ITAM 10/4 #16181
    Ted Fletcher
    Keymaster

    It was more than 40 years ago that we made that mixer, back in Windsor.

    Who would have believed at the time that equipment like this would be cherished and used again in the 21st century!

    Technically, a modern digital mixer is superior in performance and the facilities and versatility is far superior to our 1970s efforts, and yet the sound created from the Itam 10/4, the Alice 828, the 828S and other analogue mixers of the day, has a comforting warmth and ‘stability’ that is missing from later electronics.

    I can argue that it’s down to overload margins and the onset of various sorts of harmonic distortion, but then I start to sound like a HiFi anorak; the truth is complex but undeniable, as Joe Meek used to say, ‘If it sounds right………’ :geek:

    in reply to: Hooters B1 #16177
    Ted Fletcher
    Keymaster

    Why??? 😯

    The B1 output is a low impedance unbalanced feed, with 470 ohm buffer resistors. Its performance is excellent unless you want to drive audio feeds more than about 50 yards. Seriously, there is no advantage to using a transformer on the output unless you want the additional distortion created by the transformer. :)

    in reply to: Hooters B1 #16175
    Ted Fletcher
    Keymaster

    Yes, a standard 12VAC supply is all you need, the current requirement is low so anything greater than 250 milliamps will be OK.

    The B1 was a quirky but very good wide ranging mic-amp/compressor. I have just had a look at the original circuit from 1998 and it looks good to me from the perspective of 2018! :)

    in reply to: SC2 version question #16174
    Ted Fletcher
    Keymaster

    Hi Daan,

    The great thing about the very early SC2 versions was that they were impossible to make bad sounds! The later versions had wider values of attack and decay and so actually were not so easy to use, but be assured, the compression was all the same on all those SC2 compressors including the later SC2.2, they just needed a little more time to set up. The compression circuits were the same and they are the same as I am using on a new 500 series version.

    regards

    Ted

    in reply to: P38V7 #16173
    Ted Fletcher
    Keymaster

    No, there are no rack-mount compressors being made now; but I shall produce some early next year as I get many requests!

    I’m working on a 500 series stereo compressor that will also be available in the new year, it’s a version of the P38 but in the API format taking up two 500 series spaces. :)

    in reply to: Stereo Link on VC1 v.2.01 #16171
    Ted Fletcher
    Keymaster

    Hi Benjamin,

    Now this is embarrassing! I don’t have any circuit information on the VC1 version with the stereo link! But I think you will find that the co-ax socket is just an extension of the rectified sidechain, so connecting them together will allow both units to control the compression. I can’t be absolutely sure about that (without having one of the units here) but I do remember that it was not a successful facility owing to the fact that the opto cells vary so much and the compression was never balanced. As you noticed, we very quickly dropped the facility! 😳

Viewing 15 posts - 31 through 45 (of 451 total)