Transition Generation ODS #093 Inspired Build

[dbharris]

Got the preamp board loaded in. Cap can all wired up. Pot side and bus bar wired up. Bias circuit and GNFB wired in.

Next up are the novals sockets then heaters. I'm out of town next two weekends, so I am hoping to fire it up by the end of the month.

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-Dan

[martin manning]

Another work of art!

[dbharris]

Thanks Martin!

[fred.violleau]

She’s a beauty, great documented build! Can’t wait to hear it!

[dbharris]

Thanks Fred. I'm excited to hear her too!

-Dan

[Raoul Duke]

Martin’s right - very clean and authentic looking! Fantastic job!

[dbharris]

Well it's been a while haha. We are expecting our first baby in about 6 weeks so lots of other projects around the house have been higher priority. But I did have some time today to work on the amp. Finished wiring the preamp and effects loop jacks. About half way done with the heaters too.

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-Dan

[dbharris]

Alright, this build is complete! Burned in for about 20 hours so far. This is the most versatile ODS circuit I've built. Sounds great with a strat, les paul, silver sky, les paul special, and lap steel.

Does anyone know of a source for 100K 30% taper Audio pots? The 10% I have now for the Level and Ratio are not ideal imo.

I learned the importance of triple checking everything after several self-inflicted errors due to building this amp over so many months in short bursts.

I had a short to ground at my V2 dropper due to breaking a standoff and replacing it with an extra I had that was just slightly wider than the type I typically use. The lead under the board was just barely touching it. Got that sorted out.

When I built my relay PS board I went with a FWB and was going to order a 12v PT. But they were out and I ordered a 6v. I forgot all about the board now needing a doubler with my 12v relays. Of course they did not work and I had to repurpose the board into a doubler. Simple circuit so no big deal.

My quad of JJs for testing biased right up. My permanent tubes for this build would only come up to about 45%. So I adjusted to bias resistor to a 4k7 Koa half watt. All good.

I wired the Accent switch upside down. Fixed that.

I wired the dual bright switch wrong. It didn't function as a bright but instead was like a mega mid boost that made the amp really beefy and with more output. But it also kind of messed with the normal range of the tone stack. Fixed that as well.

Rolled tubes and settled with a TAD selected red base in V1, NOS RCA short grey plate in V2, and an NOS RCA long grey plate in V3. TAD red base 6L6GCM-STR for the power tubes. It sounds great!

I dialed in the OD entrance trimmer at about 22.8K to ground. I set it to 25K and with PAB and overdrive on played with it listening for when strong separation started to decline and then dialed it back a pinch.

Voltages (before I balanced the PI)
Mains 120.9

B1 434v
B2 433v

Biased at about
V4 .0467v 64%
V5 .0448v 61%
Avg 62.5%

V6 .0447v 61%
V7 .0476v 65%
Avg 63%

B3 412v
V3_a 287.8
V3_b 292.7

B4 289 3
V2a 199.3
V2b 193.6

B5 279.5
V1a 184
V1b 188.6

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-Dan

[martin manning]

Does anyone know of a source for 100K 30% taper Audio pots? The 10% I have now for the Level and Ratio are not ideal imo.

https://store.mesaboogie.com/products/p ... shaft.html

Looks great!

[dbharris]

Thanks on both!

[Raoul Duke]

Looks great Dan! I bet it sounds fantastic.
I share your observations about building over an extended period of time as well. I try to avoid it - but life comes first and always wins, lol.

[GAStan]

She's a real beauty! Inside & out. Great job!

[j0k3335]

A truly superb piece of work!

[dbharris]

Thanks guys!