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  • in reply to: Hearing problem #30695
    Ted Fletcher
    Keymaster

    I have been thinking about it!
    This problem keeps cropping up;I have had many requests for equipment to improve listening on TV.
    Presently, and partly as a result of these requests, I’m working on the development of a new TV loudspeaker (working title TVTR) which will be a simple low price device, but fitted with a form of filtering and compression specifically to help with perception of dialogue. By definition this will help with listening to all types of sound where the dynamic range is too great or where there is interfering noise.
    The new loudspeaker will be under the Orbitsound label and should appear mid next year.

    in reply to: Hearing problem #30679
    Ted Fletcher
    Keymaster

    As it happens I do have a number of compressors in stock so was able to do some experiments today……
    At first I tried putting some classical music through the limiter circuits of my new 828 Mk3 mixer. This was not a success, the limiters do the job of preventing overloads perfectly, but when pushed, add a degree of harshness without accenting the quiet sections sufficiently.
    I also tried my P38EX mastering compressor, but I think this one is generally too well behaved; it refuses to carry out the necessary increase on quiet passages.
    Lastly I tried a combination of two TFPRO538 stereo compressors in a 500 series rack. Having thought about it overnight I wanted to try using a fast and sharp compressor to bring up quiet sections and to follow it with a much slower’heavy’ compressor to operate more as an automatic gain control for the complete signal.
    Of course, the 538 is a sophisticated compressor in its own right; it already has shaped attack and release curves and reacts at different speeds depending on the level and dynamics of the signal, running two of them in series I expected a greater degree of control.
    The system works extremely well. I have the first compressor set with about 18dB of audio gain, slowish attack and fast release, with a compression ratio of about 10:1.The second compressor has about 15dB gain, fast attack and slowest possible release. The ratio is about 6:1.
    The result is an extremely complex array of time constants that hold the maximum volume level stable and brings up the volume of quiet sections by as much as 22dB with remarkably little noticeable level shifting. The result is acceptable quality and I think, offers a solution to the particular problem.
    I’m not sure that this is a practical answer as these compressors are not cheap, but it is certainly an answer. Ideally, I would design a completely new compressor fitted with dual sidechains and optical circuits to emulate the effect of the pair of 538s, but I think the cost would actually be greater than for a pair of existing 538 compressors!
    If you are interested in taking this further, please email me at [email protected]

    in reply to: Hearing problem #30677
    Ted Fletcher
    Keymaster

    Sorry to read about your hearing problem……
    The short answer is yes; it is certain that using a compressor will make it possible to hear quieter sections of music. The principle is a good one, the real question is how to produce a compressor with the best characteristics so that it works well enough without destroying the musicality of the audio.
    Over the years I have experimented with many types of compressor and have had systems that would probably do the trick, but I must think further on this…….. I’m going to consider it for a few days and will come back to you.

    in reply to: Tfpro 538 #30660
    Ted Fletcher
    Keymaster

    To those interested in the TFPRO538, there is now a new version with a modified connector arrangement so that it works OK in a standard MCI or Neve 500 series frame. See the product page for news of the version V5!

    in reply to: Modify for EQ on/off switch – Alice 828 MK1 #30658
    Ted Fletcher
    Keymaster

    Hi Ilcaccillo,
    There’s a lot going on!
    The way I changed the circuitry on the Mk3 828 to include an on/off switch was by adding a further buffer stage immeiately before the channel fader, this made the mod possible but it’s not really a practical proposition on an existing Mk1 mixer, bearing in mind that the mixer is now very old and the mod requires a great deal of work.

    in reply to: Tfpro 538 #30548
    Ted Fletcher
    Keymaster

    Hi Stefano,
    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!

    in reply to: Alice 828 from Hungary? #30514
    Ted Fletcher
    Keymaster

    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.

    in reply to: ALICE KEEPS ON GOING! #30381
    Ted Fletcher
    Keymaster

    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.

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    in reply to: 828 Mk 1 Monitor Output #30377
    Ted Fletcher
    Keymaster

    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!

    in reply to: 828 Mk 1 Monitor Output #30374
    Ted Fletcher
    Keymaster

    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.

    in reply to: Modify for EQ on/off switch – Alice 828 MK1 #16917
    Ted Fletcher
    Keymaster

    Here is the circuit diagram.

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    in reply to: Modify for EQ on/off switch – Alice 828 MK1 #16916
    Ted Fletcher
    Keymaster

    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!

    in reply to: SC rev 1.05 NEED HELP #16200
    Ted Fletcher
    Keymaster

    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 [email protected]. :)

    The additional output gain control should not affect the compression in any way. :(

    in reply to: P38 #16199
    Ted Fletcher
    Keymaster

    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 [email protected].

    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! :)

    in reply to: Alice 62/3 mixer question #16197
    Ted Fletcher
    Keymaster

    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.

Viewing 15 posts - 16 through 30 (of 451 total)