Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: zapped on December 21, 2022, 01:01:44 pm
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Seasons Greetings. It has been a very long time since I have posted on this forum. I have a very old West Laboratories. I'm trying to find someone who is familiar with West amps and the history. I think it is the Grande but that's just a guess. I have not found a matching schematic yet.It uses Dynaco III mono block Hifi amp transformers and the circuit board that holds the phase inverter tube but they did not use the tube rectifier or choke. 2 x KT88 or 6550 OP tubes and a single 12ax7 preamp circuit.
Thanks . Regards Ed
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How 'bout this? Found it on their Facebook page in a Google search.
Edit: I'd ditch the death cap setup and use a proper cord set with a ground.
https://www.facebook.com/170878092963773/posts/does-anyone-have-a-grande-schematic/2019781591406738/ (https://www.facebook.com/170878092963773/posts/does-anyone-have-a-grande-schematic/2019781591406738/)
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That's exactly like the Fender AB763 except for the UL OT. I wonder which came first. Can you share some hi-rez pics?
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JPK thank you very much for the schem. I will see how close it is to the amp. Sluckey I will try to post some pics tonight.
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One pic at a time?
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Ok. 2 at a time works.
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2 more
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I hope they are clear enough
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Last 2 thanks for looking
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Hmmm. That's not pics. That's postage stamps. :icon_biggrin:
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I will try to post again with larger photos :w2:
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That's ok. I've seen enough.
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Thanks for looking Steve. Have you seen any of these before?? I can't tell if it's a clone or just very early model.
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I never heard of this amp before your post. Google turned up some good pics of the Grande.
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Deleted
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I hope they are clear enough
Hoffman has to conserve server space, and is not a great place to upload your pictures.
High resolution (aka "large file size") can be uploaded to your account at Imgur.com. Then you can copy the "Direct Link" and paste it here using the "Insert Image" tool.
... the circuit board that holds the phase inverter tube ...
This goes to show how some comments about "good/bad printed circuit boards" may be 50 years out of date.
Usually, we read that "board mounted tube sockets are bad." Well, the kind used here (and by Dynaco) are the bad ones. Inserting/removing the tube will stress the board.
MESA uses the good board-mounted sockets today (though their older products had the bad sockets (https://images.reverb.com/image/upload/s--QEt9D_t7--/a_exif,c_limit,e_unsharp_mask:80,f_auto,fl_progressive,g_south,h_620,q_90,w_620/v1486928284/bv2vhzp5433e8runsqpr.jpg)). Their sockets are large (http://www.in2guitar.com/express/expresschassis.jpg) and apply any stress over a larger area of the board, reducing the risk of damaging traces. These larger sockets also have better insulation between pins, and are great for preventing arcing & measurement accidents.
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That's exactly like the Fender AB763 except for the UL OT. I wonder which came first.
going with Fender on this one :icon_biggrin:
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Thanks for allowing the post and comments. I was offered the unit because of an interest in Grand Funk Railroad. Legend has it that West was the favorite amps for GFR. Thanks again