Randall Diavlo RD1 tube layout?

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GJgo

GJgo

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So I just picked one of these up used at GC for $170, for a bedroom amp. I like the bigger brothers a lot so I figured what the hell.

I see it has a pair of 12AX7s, and a 12AU7 for the "power tube". Does anyone know..

- V1 should be pretty straightforward.
- Is V2 a preamp stage, or does this layout use it as a phase inverter?
- Any opinions on replacing the 12AU7 with a different 12A*7 tube type for...?
 
I think I found the answer about the 12AU7 in some tube forums- while the "gain" is low, it dissipates around 2.5 watts where the 12AX7 dissipates around 0.3w. Didn't see what the 12AT7 puts out, but I'm guessing they use the 12AU7 for a reason. Seems popular with the DIY guys in 1W push/pull setups.

Now just curious about the V2 function.
 
Got the amp, rolled some pre tubes. Just like its bigger brother my RD20, the Chinese tubes it shipped with were very high gain but sounded fizzy. I ended up running a Tung Sol in V1 & a LPS in V2. Just left the Chinese 12AU7 in there for now.

This amp has no clean headroom. I didn't expect much, but wow. My active pickups don't help...

The gain voicing sounds great for a bedroom amp- blows away any low wattage solid state job IMO. It sounds a little thin with the supplied 8" speaker, but it will push my 4x12 cab at decent bedroom levels no problem. With only 3 knobs & the TSS switch there are really just a couple good sounds, which I expected, but they are good. The TSS switch does exactly what you need to for switching between scooped & middy, so it's fine that it doesn't have separate knobs for this.

I'd love to hear a RD5 since it runs class A! I think the Diavlos are killer little metal amps for the money.
 
GJgo":20shvpj8 said:
Got the amp, rolled some pre tubes. Just like its bigger brother my RD20, the Chinese tubes it shipped with were very high gain but sounded fizzy. I ended up running a Tung Sol in V1 & a LPS in V2. Just left the Chinese 12AU7 in there for now.

This amp has no clean headroom. I didn't expect much, but wow. My active pickups don't help...

The gain voicing sounds great for a bedroom amp- blows away any low wattage solid state job IMO. It sounds a little thin with the supplied 8" speaker, but it will push my 4x12 cab at decent bedroom levels no problem. With only 3 knobs & the TSS switch there are really just a couple good sounds, which I expected, but they are good. The TSS switch does exactly what you need to for switching between scooped & middy, so it's fine that it doesn't have separate knobs for this.

I'd love to hear a RD5 since it runs class A! I think the Diavlos are killer little metal amps for the money.
Click to expand...

I owned the RD45H twice. Loved it both times, and almost bought another a few months ago. I owned a Blackstar HT-5 head that I liked a lot, but would love to try the RD5 over it. I love the Randall's voicing!
 
If anyone grabs the 5 watt combo be warned that fitting a new speaker in there is a major challenge. So much as though I gave up on mine and sold it. The 6V6 drops down behind the magnet. Any speaker I tried would hit the tube. The stock speaker has a pretty small and thin magnet on it. That's why it fits but most others won't. Just be sure to measure before buying.
 
Don't be sad, the missing guts are currently with Mike B. for a 30 year refresh. :)
 
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