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ARCHIVED FORUM -- April 2007 to March 2012
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This is the first Archived Forum which was active between 17th April 2007 and 1st March February 2012

 

Latest post 07-26-2011 12:36 PM by tournedos. 30 replies.
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  • 07-25-2011 3:51 AM In reply to

    Re: HiFi Stereo Amplifier 608

    classic:

    Martin, please explaine in danish the [ Bandmaster ] receiver, what is the dansih name for that one? or better the type if possible.

    Frede

    In Sweden the Bandmasters come up for sale fairly frequently, so I suppose that name was used when they were sold in Sweden. Prices are usually in the 60 euro range, unless the condition is near mint.

     

     

  • 07-25-2011 4:18 AM In reply to

    Re: HiFi Stereo Amplifier 608

    Hi Wolf, hope you haven't yet given up hope for getting an answer!

    wolf251066:
    I read what I can find on the internet about this amplifier and came to sites that had the technical data for the Type 608 and there was a description of some kind of "adaptor" with which the output sensitivity of the "Gramophone" input can be changed from Magnetc Pickup 2 mV to Crystal Pickup 50 mV - now i am not very good at this technical stuff, but maybe the low volume when listening to records has something to do with that ? But I cannot find that "Adaptor" - is that a separate unit or something inside the amplifier ?

    Yes, this level incompatibility must be the issue. I don't know about this "adaptor" myself, but whether it was an internal circuit board or an external box, it must be very hard to find nowadays. Magnetic pickups were rare in those days, so it probably never was a popular option.

    But, this is exactly the same problem you have when attaching a modern MM pickup to a line level input. Therefore you can try using any external RIAA preamplifier to solve this.

    -mika

  • 07-26-2011 1:40 AM In reply to

    Re: HiFi Stereo Amplifier 608

    Thanks Mika, I tried to go with external RIAA pre amp (NAD PP1) via the Tape input, but the sound was missing the "magic" compared with the "Phono" input ... I guess the one 12AX7 / ECC83 tube in the 6o8 is for the Phono input and bypassing it loses the special sound ?

    Now could I try to go with external RIAA pre amp in the Phono input ?

  • 07-26-2011 4:16 AM In reply to

    Re: HiFi Stereo Amplifier 608

    I only now realized that we have the user & service manuals for this amplifier on site Smile

    I wasn't aware that it actually has a transistorized preamplifier built in (circuit board 915 H 23 B, two per set). Apparently it can be changed between dynamic (2 mV) pickup and crystal (50 mV) pickup levels by replacing some kind of a plugin board, which contains a few resistors and capacitors. Board 915 H 50 is for crystal pickups, do you have those installed now?

    The tape input should be the one to use with an external amp, but it may indeed sound different (more modern, or simply duller if you like). The internal preamp uses germanium transistors which probably colour the sound somewhat.

    EDIT: the interchangeable equalizer boards should apparently be sticking up in the left rear corner of the chassis. 915H50 for crystal pickups, 915H24 for magnetic pickups. There are also two 470k resistors at the phono input connector, they are short circuited for MM pickups.

    If you have the boards for crystal pickups now, they should be easy to modify for MM use if nobody is able to supply the alternative boards for you.

    -mika

  • 07-26-2011 12:07 PM In reply to

    Re: HiFi Stereo Amplifier 608

    Thanks again, I will open it up and take a look. Any pointer where i can find the user & service manuals for this amplifier here ?

  • 07-26-2011 12:36 PM In reply to

    Re: HiFi Stereo Amplifier 608

    Main site -> products -> user & service manuals, but you'll need to upgrade your membership before you can access them.

    The adapter part of the schematic is really simple though, I don't think anybody will kill me if I supply just that as an appetizer. The service manual is in Danish anyway Smile


    -mika

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