New amp build

[splgeo]

new build, Skyline, low gain od, 220/150/180/120 el34

od entrance is 470k/47pf, 200k, 25k 4.7k tail, 68k grid

[splgeo]

pic of the outside ce chassis

[Guy77]

Hi splgeo, looks great!! Every time I see a new build I get the itch to start one!
I am getting tired of drilling chassis's myself. I may order one as well for next build.
Can you tell me what models you used for the Power and Output transformers?
Also is this a HRM style build?

Cheers!

keep the iron hot.

Guy

[splgeo]

Skyline HRM 220/150/180/120 low gain od entrance. el34 Classic-Tone iron Marshall 100watt 1.7K, Fender Twin power and choke

[Guy77]

Thanks for the update.

I also ran Marshall style output and Fender power transformers in a Brown Note d'lite 44 build.
Never thought Marshall and Fender could sound so good together until I tried it!

Cheers!

[UltraHookedOnPhonix]

splgeo,

What is the Wattage of those 270K bleeder/balancing resistors in your build? Assuming a 460-ish plate voltage, those should be at least 1W (2W even better IMHO).

Congrats on the new build!

[splgeo]

they are some that I had laying around. ive got a mouser order on the way. I built it after the 97Notes

[martin manning]

What is the Wattage of those 270K bleeder/balancing resistors in your build? Assuming a 460-ish plate voltage, those should be at least 1W (2W even better IMHO).

At 460V B+ they are dissipating less than 0.2W each, so 1/2W should be enough, no?

[splgeo]

also, ive been looking around, and haven't found the answer. What do the really amps use as far as resisters. Ie all signal path are carbon comp, and plates and cathodes are metal film? what do the real amps use?

[sonicmojo]

also, ive been looking around, and haven't found the answer. What do the really amps use as far as resisters. Ie all signal path are carbon comp, and plates and cathodes are metal film? what do the real amps use?

I think you are on the right track. If you look very closely at the layouts and pictures in the Dumble Files section you'll get a decent idea. The different types are mostly marked on the layouts but the extra pictures help too. Good luck finding any of those red Piher carbon film resistors though. They are scarce.

[ToneMerc]

also, ive been looking around, and haven't found the answer. What do the really amps use as far as resisters.

It depends on which era; earlier amps had 1% MF on plates and cathodes and 5% CF in the signal path mostly. The 80's grail tone amps had mostly 2% CF across the board, but you will find amps like #183 which has MF on the plates.Then when you get into the 90's it obvious that his stash of 2% CF resistors started to get low and he used more of the MF resistors.

At the B+ Nodes very early amps had CC and then he transitioned to CF. At V1b grid stopper he occasionally used a thick film glass passivated MF.

In his hey day he had a real affinity for European resistors, even the blue MF NTE reseller resistors of the 90's.

TM

[splgeo]

thank you for the help the 12k/10k resistor will come in today. I post up how close my voltages are to the 97notes.

[UltraHookedOnPhonix]

What is the Wattage of those 270K bleeder/balancing resistors in your build? Assuming a 460-ish plate voltage, those should be at least 1W (2W even better IMHO).

At 460V B+ they are dissipating less than 0.2W each, so 1/2W should be enough, no?

Martin, you are of course correct. I ran it as the entire 540K string, forgetting to divide by 2...yielding a quite sensible margin of error of a bazillion%. Like you said, there should be about 195.5mW through each resistor. I wonder why Dumble consistently used 2 Watters in that slot but 1/2W in the rest of the PS because even though the off-load voltage rises by about 20V in standby, it really doesn't warrant using chunkier resistors here.

[ToneMerc]

thank you for the help the 12k/10k resistor will come in today. I post up how close my voltages are to the 97notes.

AFAIK, that "97 ODS" was not an actual amp but just an conceptual layout. When you get down to the brass tacks, the only voltages that matter are what's in your own amp. You will also find that by just rolling different preamp tubes the voltages will change.

My personal experiences with HRM's is that it's a thin line between sounding good and sounding like ass and V2 plate voltage has to be within a certain window.

YMMV, the real building is tweaking to taste.

TM

[ToneMerc]

I wonder why Dumble consistently used 2 Watters in that slot but 1/2W in the rest of the PS because even though the off-load voltage rises by about 20V in standby, it really doesn't warrant using chunkier resistors here.

UHOP, I think they were mostly 1W in the rail, but I have seen .7W 22Ks used. He also used a 2W for the rail bleeder in the MM style supply amps.

TM