Thoughts on the Marshal 8008 Valvestate

[ghosty999]

I just picked one of these up cheap to replace the Cat C "Solid State" Thomann power amp which sounded awful and thin. Got it all plugged in and running into a Greenback 2x12 marshall cab in stereo with a ADA MP-1 and MIDI Verb3 at the front end. Anyone have any advice or experience with these? I've heard there is not alot of output protection and they can go on fire haha. I have Valvestate mode switched on and sounds 10x better than the Thomann

 

[Hung Huy Tran]

I've had a Lee Jackson Sp-1000 for years and love it. I've always wanted to try out an 8008 because as I've always liked the VS100 and 8100 heads.

Anyway, congrats on the power amp and looking forward to clips at some point!

 

[ghosty999]

That looks like an interesting power amp! Not heard of them before. I will to an ADA-MP1 + 8008 video soon. Hopefully playing with a new Nightswan replica me and my friend is building

 

[messenger]

They're good enough for Billy Gibbons

 

[geetarmikey]

I've used this with my GSP1101 in the past. It did the job well (Didn't like the valvestate mode on it, seemed a bit scooped), but when I got my Velocity 300 the difference was very obvious in terms of clarity and punchiness.

Good for a spare, but I don't use it out of choice anymore.

 

[ghosty999]

I've used this with my GSP1101 in the past. It did the job well (Didn't like the valvestate mode on it, seemed a bit scooped), but when I got my Velocity 300 the difference was very obvious in terms of clarity and punchiness.

Good for a spare, but I don't use it out of choice anymore.

What does the Valvestate actually emulate in terms of tube power? I haven't tried the other setting, seems to sound okay with the ADA, it just lacks the bottom end push that my EL84 20/20 has

 

[raiken]

Valvestate mode enables current-mode feedback on the power amp instead of voltage-mode feedback. Current-mode feedback makes the output impedance higher, like a tube amp output stage, while voltage-mode feedback makes the output impedance essentially zero.

Higher output impedances react more to the cabinet impedance, which peaks up at the low resonant frequency point and rises at higher frequencies. If you drive a speaker cabinet with a zero output impedance, the amp doesn't respond to these impedance peaks, so it sounds flatter and more midrangey, and less dynamic. If you drive it with a higher output impedance, the amp responds to the cabinet impedance peaks and has a low-end resonant boost and high-end boost, and sounds more "tubey" and natural.

FWIW, I have a Marshall 8008 power amp I used back in the rack days, but it has the black front instead of the gold front. I love it, it sounds very good.

 

[ghosty999]

Valvestate mode enables current-mode feedback on the power amp instead of voltage-mode feedback. Current-mode feedback makes the output impedance higher, like a tube amp output stage, while voltage-mode feedback makes the output impedance essentially zero.

Higher output impedances react more to the cabinet impedance, which peaks up at the low resonant frequency point and rises at higher frequencies. If you drive a speaker cabinet with a zero output impedance, the amp doesn't respond to these impedance peaks, so it sounds flatter and more midrangey, and less dynamic. If you drive it with a higher output impedance, the amp responds to the cabinet impedance peaks and has a low-end resonant boost and high-end boost, and sounds more "tubey" and natural.

FWIW, I have a Marshall 8008 power amp I used back in the rack days, but it has the black front instead of the gold front. I love it, it sounds very good.

Really interesting information thanks man! I'm running it through an old Marshall 2x12 in my apartment. No idea what speakers are in it, might be chinese Celestions. Bought the 8008 so I can play the ADA at low volumes and occasionally high volume at practice. It seems to respond pretty well to the cab, I'd love to find out what model the cab is so I can find out about the output impedance that you mention.