Revisit High-Plate Classic with a 5-piece chassis

[ijedouglas]

After the positive results from previous builds using a 5-piece chassis, I'm making my way through my amps and rebuilding them. This was an amp I completed a couple of years ago and I've slowly upgraded it as I found better parts. It was a good sounding amp but I wanted to see if the new chassis provided any improvement. I took quite a bit longer to build the chassis as I wanted to avoid having to re-paint it (previous builds had issues with the paint and clear-coat).

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[GAStan]

Looking great Ian, as always with your work. Nice job with the clear adhesive (RTV?) on the power caps, barely noticeable-I missed it at first.

[mikeram]

Beautiful build! Did you build a new board for the preamp? Looks pretty clean. Looks like you found a blue tantalum capacitor similar to what HAD used. Is that NOS or new stock?

Thanks,

Mike

[ijedouglas]

Thanks Glenn and Mike.

The tantalum is NOS. I have no idea the brand but they sound great

[timrobertson100]

What kind of wire are you using there, please?

[ijedouglas]

What kind of wire are you using there, please?

20AWG solid core

[ijedouglas]

Before the preamp board goes in:

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[rootz]

Absolutely beautiful work Ian!! Incredible to see even the correct relays (as well as all other NOS parts). That attention to detail gets me hooked on every single one of your builds.

So this is a mix between #94 and #128 you said. Can you share what makes #128 what it is? For example: I see a cap over the 220k grid stopper of V1b. That cap is not in #94 I believe. Is it in #128? I also believe the trigger trimmer was supposed to be 1meg in #94 (or at least by me, who has never been in that amp must I say). Is it confirmed to have a lower value?

[ijedouglas]

Absolutely beautiful work Ian!! Incredible to see even the correct relays (as well as all other NOS parts). That attention to detail gets me hooked on every single one of your builds.

So this is a mix between #94 and #128 you said. Can you share what makes #128 what it is? For example: I see a cap over the 220k grid stopper of V1b. That cap is not in #94 I believe. Is it in #128? I also believe the trigger trimmer was supposed to be 1meg in #94 (or at least by me, who has never been in that amp must I say). Is it confirmed to have a lower value?

Thanks for the kind words. As far as I know the two amps differ, as you noted, in the OD trimmer (#094 1Meg / #0128 100K) and V1B 500pf snubber (missing on #094). I am really just using them as a lead dress guide. #0128 has metal film on the bass pot and deep switch, a CTS OD trimmer and 200pf bright cap whereas #094 has CF, piher OD trimmer and a300pf bright cap. I went with CF on bass and deep, 100k piher on OD, 500pf snubber on V1b and 200pf bright cap. I think #0128 also had 2 x 40uf can cap on V1 and V2 whereas #094 has 2 x 20uf. I am probably closer to #0128 in circuit.

[ijedouglas]

Finished. Amp fired up first time with no issues. Sounds pretty good out the gate with a strat. I did notice that the clean is a lot quieter than my other amps. When I kick the OD in it is back to ear-bleed so I need to check a few things. I think I'm also going to go back to the 500K trimmer. The OD sounds good but I think the 500K will beef it up a little (especially with a strat)

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[dbharris]

Looks great, Ian! Would love to hear a clip once you get it dialed in. What tubes are you running?

-Dan

[ijedouglas]

Looks great, Ian! Would love to hear a clip once you get it dialed in. What tubes are you running?

-Dan

Thanks Dan. I have NOS GE 12AX7WA preamps and TAD STR redbase 6L6s

[rootz]

Damn, I would hang that chassis on the wall and just stare at it for days.

How are you liking those rebase tubes by TAD? I recently had one fail in a quad in a new amp, some nice fireworks inside. Already had a bit of discoloured glass before installation, but I thought they would be good to go. I was wrong. Whenever I test such a premium TAD tube, they seldomly test accordingly. Some as much as 50% off from the datasheet and not at all like a Telefunken ecc83 they are based on. Not to worry you Ian, I just might have had a Monday morning tube...

[dbharris]

Looks great, Ian! Would love to hear a clip once you get it dialed in. What tubes are you running?

-Dan

Thanks Dan. I have NOS GE 12AX7WA preamps and TAD STR redbase 6L6s

I just put a quad of those in my #102. I am liking them so far but still burning in. One has drifted more than the others. I have a quad of the old version TAD black plates in my JM Sig and like them a lot.

[ijedouglas]

Looks great, Ian! Would love to hear a clip once you get it dialed in. What tubes are you running?

-Dan

Thanks Dan. I have NOS GE 12AX7WA preamps and TAD STR redbase 6L6s

I just put a quad of those in my #102. I am liking them so far but still burning in. One has drifted more than the others. I have a quad of the old version TAD black plates in my JM Sig and like them a lot.

I'm really liking them. Did you get Apex matched with burn-in?