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Help! My Gretsch 1965 6162 Amp Sounds Anemic. Help!!

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  • Help! My Gretsch 1965 6162 Amp Sounds Anemic. Help!!

    Help. I need recommendations on how to bring anemic sounding Valcos back to life.

    Hello everyone,

    Admittedly, I'm a valco amp junky and just can't help myself from buying these old amps online. Unfortunately, there are times when one of these beauties arrives, I plug it in, dime it and sadly my excitement turns to disappointment when all I get is an anemic clean tone when I was expecting a roar. Such was the case with a Gretsch 6162 I recently got from the west coast. I played a 6162 before that roared but this one definitely doesn't. Not to mention, I have a couple more Valcos in my collection that should roar but don't. This being the case, I set myself out on a mission on how to bring these back to life. So here I am praying that the collective experience of this forum can help me trouble shoot this anemic amp and replace what ever needs replacing to bring it's former glory.

    I did do a bit of homework before posting and from what I've read on this forum (as well as other's) I found the following:

    1) Check/replace the ground reference caps coming off the preamp plates (this was Leon's advice). Many valcos use the brown paper variety but mine has the dark red (polyester??) ones in place. Question: would these dark red ones be as prone to fail as the brown paper ones??

    2) Check/replace the white 35uf mallory electrolytic cathode bypass caps. Now where does one get 35uf caps these days??

    3) Check OT. What are the chances of a bad OT in these anemic valcos? Saying that, I know I've had at least 2 Supros with mismatched OTs. A 1961 1624T with a replaced OT specced for an 8ohm speaker hooked up to a stock 4ohm rola
    The other was a 59 Coronado with a replaced OT spec'd out for a 3 speaker layout (like a 6161). I replaced that one with a Thunderbolt OT and a fresh Celestion G30H. Now that amp just screams.

    4) Check Tubes: Easy enough but for a 6EU7 with is hard/expensive to find. I've read that rewiring that socket to take a 12ax7 is easy to do.

    5) Check Speakers: easy enough to do.

    Now can anybody here add to this. What would be the logical trouble shooting approach to finding the problem with an anemic sounding 6162.

    Schematic link (mine is the single channel version):

    http://www.guitaramplifierblueprinti...es/6162sch.gif

    Here is a link to some pictures of my anemic 6162.

    https://www.dropbox.com/sh/yv7xsmkuc...rpMjjzTVE-OiHa

    Any comments would be appreciated. Thanks

    Joseph

  • #2
    The first thing I would do, especially for an anemic amp, is to replace the filter caps. The orange Mallory dates to 1968 ......over 45 years old. Also replace the multi-section can capacitor. You'll want higher voltage caps due to the higher wall voltage we have today. Lots of vendors will have these....AEC, Mojo, Triode, etc. The power supply has to be working properly for everything else in the amp to do their jobs. Other than tubes, filter caps are the most likely culprit. Do this before you start messing around with coupling caps, transformers, etc.

    Comment


    • #3
      Pardon my ignorance here, but are you describing a loss of volume/power or a loss of tone/frequency response?

      Comment


      • #4
        The schematic doesn't seem to match the images. For example I see 6EU7 in the power amp section whilst the schematic has 12AX7.

        BTW you can buy tube adapters off eBay. They have a little PCB inside with the pins that is wired to the socket terminal to suit. I think they come prewired for a 6CG7 but I think you should be able to pull them apart and rewire.
        Experience is something you get, just after you really needed it.

        Comment


        • #5
          Hi Cluster
          Looks like you've got a good restoration project there.
          Down here in the land of the kangaroo we don't see to many of these "American bargain bin" amps although
          we had our own variation with Goldentone, Moody & Maton etc.

          See here
          http://www.ozvalveamps.org/
          Australian and New Zealand valve amplifiers for guitar and P.A. c1930's - 1970's.


          Regarding your query about 35uF capacitors 33uF is acceptable although
          if money is no object Mouser seems to have Vishay / Sprague (formally Philips as I understand)
          capacitors of that value. (The Australian prices are shown.)

          Mouser Part #: 75-TE1306-E3
          Manufacturer Part #: TE1306-E3
          Manufacturer: Vishay / Sprague
          Description: Aluminum Electrolytic Capacitors - Leaded 50V 35uF
          Pricing (AUD) 1:$4.91

          OR (below is not stocked not sure why they list it...?)

          Mouser Part #: 598-NLW35-50-PB
          Manufacturer Part #: NLW35-50-PB
          Manufacturer: Cornell Dubilier
          Description: Aluminum Electrolytic Capacitors - Leaded 35UF 50V
          Pricing (AUD) 1: $6.39 (Non stocked)

          Something like this should be fine

          ELNA-74413 33uF / 50VDC, ROA Series, 10mmD x 12.5mmL, Each $1.50 pcX USD Price

          (And 52Bill to me "anemic" means both !)

          This MEF link may be of interest

          http://music-electronics-forum.com/t15379/

          Had a quick look at your photos and couldn't help noticing where 2 of the half watt resistors had been replaced
          and am going to suggest you check all the values in the HT circuit.
          Its possible something might be starved of power !

          Attaching the schematic with circled values to check.

          Click image for larger version

Name:	6162schBIG.jpg
Views:	1
Size:	136.9 KB
ID:	833708

          Comment


          • #6
            Originally posted by 52 Bill View Post
            Pardon my ignorance here, but are you describing a loss of volume/power or a loss of tone/frequency response?
            Sorry for the confusion. I meant volume/gain loss. Not tone.

            Comment


            • #7
              Originally posted by nickb View Post
              The schematic doesn't seem to match the images. For example I see 6EU7 in the power amp section whilst the schematic has 12AX7.

              BTW you can buy tube adapters off eBay. They have a little PCB inside with the pins that is wired to the socket terminal to suit. I think they come prewired for a 6CG7 but I think you should be able to pull them apart and rewire.
              thanks. yes the schematic shows a 2 channel 6162 with a 12ax7 pi. mine is a one channel with a 6EU7. everything else is the same. i couldn't find the exact schematic.
              Last edited by cluster; 06-26-2014, 10:42 PM. Reason: error

              Comment


              • #8
                Originally posted by 66tele View Post
                The first thing I would do, especially for an anemic amp, is to replace the filter caps. The orange Mallory dates to 1968 ......over 45 years old. Also replace the multi-section can capacitor. You'll want higher voltage caps due to the higher wall voltage we have today. Lots of vendors will have these....AEC, Mojo, Triode, etc. The power supply has to be working properly for everything else in the amp to do their jobs. Other than tubes, filter caps are the most likely culprit. Do this before you start messing around with coupling caps, transformers, etc.
                Yes. I also heard (from Leon) that those dark red/brown caps off the preamp plates should be changed too. Apparently, they go bad easy.

                Comment


                • #9
                  Originally posted by oc disorder View Post
                  Hi Cluster
                  Looks like you've got a good restoration project there.
                  Down here in the land of the kangaroo we don't see to many of these "American bargain bin" amps although
                  we had our own variation with Goldentone, Moody & Maton etc.

                  See here
                  Classic ANZ Valve Guitar Amplifiers
                  Australian and New Zealand valve amplifiers for guitar and P.A. c1930's - 1970's.


                  Regarding your query about 35uF capacitors 33uF is acceptable although
                  if money is no object Mouser seems to have Vishay / Sprague (formally Philips as I understand)
                  capacitors of that value. (The Australian prices are shown.)

                  Mouser Part #: 75-TE1306-E3
                  Manufacturer Part #: TE1306-E3
                  Manufacturer: Vishay / Sprague
                  Description: Aluminum Electrolytic Capacitors - Leaded 50V 35uF
                  Pricing (AUD) 1:$4.91

                  OR (below is not stocked not sure why they list it...?)

                  Mouser Part #: 598-NLW35-50-PB
                  Manufacturer Part #: NLW35-50-PB
                  Manufacturer: Cornell Dubilier
                  Description: Aluminum Electrolytic Capacitors - Leaded 35UF 50V
                  Pricing (AUD) 1: $6.39 (Non stocked)

                  Something like this should be fine

                  ELNA-74413 33uF / 50VDC, ROA Series, 10mmD x 12.5mmL, Each $1.50 pcX USD Price

                  (And 52Bill to me "anemic" means both !)

                  This MEF link may be of interest

                  http://music-electronics-forum.com/t15379/

                  Had a quick look at your photos and couldn't help noticing where 2 of the half watt resistors had been replaced
                  and am going to suggest you check all the values in the HT circuit.
                  Its possible something might be starved of power !

                  Attaching the schematic with circled values to check.

                  [ATTACH=CONFIG]29420[/ATTACH]
                  Wow. Thanks for that great info. Will source those parts you mentioned.

                  Comment

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