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FDP Forum / Amp Mods, Repairs, and Projects / The Cure for Cat Scratch Fever

Leftee
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VA

Jan 17th, 2019 08:36 AM   Edit   Profile  

I have a soft spot for old, abused Marshalls. I picked this one up on Reverb, cheap, and it was kinda sad.

Here kitty kitty

Leftee
Contributing Member
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VA

Jan 17th, 2019 08:40 AM   Edit   Profile  

Here it is today. A new handle is on order.

I also did the stacked op-amp mod, so it has richer gain.

The previous owner had put a WGS Retro 50 in it. It's a great speaker for the amp. I guess the previous owner (before the last guy) had stuck an 8 Ohm speaker in it as something happened to the original 4 Ohm.

Any ways - the amp sounds great, now!

It's an '83, based on the S/N.

No kitty

ejm

usa

Jan 18th, 2019 09:57 AM   Edit   Profile  

Just curious: How did you do the stacked op amp mod?

Did you solder them piggyback?
Did you use a dual chip adapter?
And.....
What op amps did you or have you tried?


Leftee
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VA

Toxic Humility
Jan 18th, 2019 12:45 PM   Edit   Profile  

Soldered a new pair piggy-back. Took the original out and installed the new pair.

I used 1458s - as it was the stock chip in the amp. I have tried JRC4558s before. Those were smoother but also noticeably noisier. They tended to squeal if the gain was cranked.

I did install an 8 pin socket in a 5005 years ago so I could try different chips.

(This message was last edited by Leftee at 05:11 PM, Jan 18th, 2019)

ejm

usa

Jan 19th, 2019 08:25 AM   Edit   Profile  

There's a whole voodoo thing about using different op amps, stacking them, etc. Just like swapping tubes.

In the right circumstances it can make a noticeable difference.

You probably know this, but Monte Allums (among others, probably) sells adapters/sockets for stacking op amps without soldering them on top of each other.


Leftee
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VA

Toxic Humility
Jan 19th, 2019 01:22 PM   Edit   Profile  

Yeah, but I haven’t gone that road.

I’ve got 2 JCM800 SS amps and both now have stacked op-amps. (-:

Years ago when I did the Lead 12 I really liked the 4558s. But the noise was too much.

I’ve got a newish Boss SD-1 that I stacked 4558s. That’s all I did to it, though. I definitely like it better.

But I really don’t think I want to deep dive this world. Not enough time.

(This message was last edited by Leftee at 03:24 PM, Jan 19th, 2019)

Leftee
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VA

Toxic Humility
Jan 19th, 2019 02:21 PM   Edit   Profile  

Re-griling the 5275 now. It didn't have CSF. Just a bit too much sun. The grill cloth from the JCM800 series was always bad about fading.

External link

(This message was last edited by Leftee at 06:39 PM, Jan 19th, 2019)

Peegoo
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Just beyond Mars

there's a world of fools
Jan 19th, 2019 02:33 PM   Edit   Profile  

That sad little amp looks quite happy now!

Nice work, Leftee.

Leftee
Contributing Member
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VA

Toxic Humility
Jan 19th, 2019 04:41 PM   Edit   Profile  

Thanks!

Here's the 5275 all gussied up.

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FDP Forum / Amp Mods, Repairs, and Projects / The Cure for Cat Scratch Fever




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