It's been on the shelf for 15 or so years the PT was bad and I used the OPT
for a Dumble build. So it has all changed Iron I can go JTM-45 or 75
I have two OPT for it KT66 or KT77, EL34 or KT88 I'm thinking to start
with a GZ34 with GEC KT77
Steve.
PARK-75
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Re: PARK-75
How much B+ are you expecting? Do you have the rest of the amp?
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Re: PARK-75
a park 75 is just a jmp50 with kt88s. a jtm45 has a very different OT
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Re: PARK-75
Thank you.
I have both OPT and the PT is dual voltage secondary's high and low plus 5v taps. Well see how it ends up. I want to start with a GZ34 with GEC KT77
it may be to much for the GZ34 if so I will use the JTM45 OPT with 6L6 or Kt66.
Steve.
I have both OPT and the PT is dual voltage secondary's high and low plus 5v taps. Well see how it ends up. I want to start with a GZ34 with GEC KT77
it may be to much for the GZ34 if so I will use the JTM45 OPT with 6L6 or Kt66.
Steve.
Re: PARK-75
It's a mess now but I should have all the NOS resistors to make it real.
Steve.
Steve.
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Re: PARK-75
Did Park 75 ever have a GZ34? The rectifier socket may be in a chassis hole originally used for a cap.
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Re: PARK-75
The park 75 never had a recto tube, that hole was for another filter and a filter that it needs!!!!!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: PARK-75
If you already have the JTM45 replacement trannies I guess your asking for suggestions is rhetorical. Still, my suggestion would be to use its proper trannies: 784-139 & 1202-118, especially if you still have the original cab in fair shape with the Park badge intact and the front or rear panel isn't chewed up. I get off on proper restorations, but that's just me. I'd go with Marstan or Merren iron and put a search for orig trannies in my ebay faves and wait over the years for something to show up, PTs probably never but 139 OTs do show up occasionally.
Why so enthused with the tube rectifier for this one? If you're willing to settle for a Duane Amp with EL34s instead of a JTM45, Marstarn has a PT with 5V + high/low HT taps. And just so it looks right you should try and find a McMurdo socket if you insist on this. Finding just one isn't as hard as a full set.
Anyway, for me plopping a restored Park 75 down whereever you show up will sure elicit attention. And you'll have a very versatile Marshall as it's just a JMP50 with KT88s. With a tube swap and a few, fast, cap and resistor swaps you can have every 50W Marshall made btwn the late '60s and the mid '80s.
Why so enthused with the tube rectifier for this one? If you're willing to settle for a Duane Amp with EL34s instead of a JTM45, Marstarn has a PT with 5V + high/low HT taps. And just so it looks right you should try and find a McMurdo socket if you insist on this. Finding just one isn't as hard as a full set.
Anyway, for me plopping a restored Park 75 down whereever you show up will sure elicit attention. And you'll have a very versatile Marshall as it's just a JMP50 with KT88s. With a tube swap and a few, fast, cap and resistor swaps you can have every 50W Marshall made btwn the late '60s and the mid '80s.
Last edited by rp on Tue Mar 03, 2015 6:27 pm, edited 1 time in total.
Re: PARK-75
As far as options go, I have put KT-88 in a 100 watt Marshall and I didn't think it was worth the pain, the amp ran hotter, the output valves were never correctly biased as I feared they would take out the power or output transformers. I didn't think the extra headroom was worth the effort.
Should you go down the KT-88 path I'd get transformers that are up to the task or use KT-77's.
Should you go down the KT-88 path I'd get transformers that are up to the task or use KT-77's.
Yours Sincerely
Mark Abbott
Mark Abbott
Re: PARK-75
I guess I got stuck on the GZ34 on my last 3 builds.
I have Marstan 1202-118 and 784-139 in it now and a new choke
I may as well start it off stock with the exception of the KT77'S
I have the head box with the Park logo.
Steve
I have Marstan 1202-118 and 784-139 in it now and a new choke
I may as well start it off stock with the exception of the KT77'S
I have the head box with the Park logo.
Steve