PRS HX/DA Amp

[Zen Guitar]

I currently have one of these that I am demoing and am really impressed. I was wondering if any of the amp gurus here could tell me how the circuit on these amps differs from a stock late '60's Plexi circuit? Seems like there might be a bit extra gain on tap. I find myself preferring to set the switches to the HX (lead spec) mode. The MV works really well... Wondering if this is just a Lar Mar PPIMV or something different?

Cheers!

[whitewave]

you should tell us!
The video where Paul plays it in PRS factory is quite impressive. I have a gut shot where it seems that the amp is based on 1986 model, the DA (Duane Allman) position. The shot isn't so detailed, and I cannot read most of cap values. Phase inverter section is from the 1986.
The first switch is a shared/split cathode switch. Values here seems way different from regular ones, but cannot read them.
Second switch should bypass V2a Rk with a small cap. Does it make a very noticeable difference?
Third switch does something I cannot understand in NFB section.
Master Volume seems regular LarMar.

Could you upload some detailed internal shots?


Thanks.

[neikeel]

Looks like a hybrid of a 1986 and a 1987 with a PPIMV (Lar Mar as the 220k bias feed resistors are missing from the board) as the extra knob.

PI and couplers are exact 1986 and the three mini toggles seem to control a V1 shared/split cathode, a switch in the tone stack and bias changes.

Is that a big Jensen PIO cap on the V1b coupler? Filtering looks to be 100uF PI, 47uF mains (100+100 in series), 22uF screens (47 + 47 in seroesand 33uF in preamp but I could be wrong!

Seems there is a spare space for another preamp tube and a valve rectifier too. Interesting to see carbon comps, Sozos and eyelet type board construction.

Also interesting that some of the amps here have neater wire dress

[Zen Guitar]

Thanks, guys! I'll see about some more detailed pics. I'd love to know the difference between the HX/DA amp with everything set to HX (lead) vs a standard '68 JTM50 lead circuit. Considering what to buy and, although I like the HX/DA very much, I'd probably leave it set to HX. And, I'd prefer a more classic vintage Marshall style look. It's also not exactly inexpensive. Wondering if a quality JTM50 clone with PPIMV wouldn't suit me better.

Cheers!

[Zen Guitar]

I spent some time under the hood and would love to hear everyone's assesment of how the circuit differs froma stock 1987 or 1986 circuit from 68-69. However, before posting any pics, I wanted to first ask if this sort of thing was okay?... I'm a relative newby and I don't want to step on the toes of the kind folks at PRS or break any forum rules...

Also, pics are around ~57MB. Would I just copy them into a post? I don't have any photo sharing, etc. If someone would prefer me to send them and they host the pics, just PM me.

Thanks!

[neikeel]

Cool with me!

[demonufo]

I don't think there's really anything groundbreaking in there, or anything that PRS could truly claim as their own for them to have any right to get upset about it. As an owner, I think you have every right in this instance. It's not like they've asked you to keep the guts a secret.

[whitewave]

I can host images if you want

[bman5150]

I don't know a thing about any tech when it comes to the innards of a tube amp. However, I got to play this amp at Sweetwater's Fort Wayne, IN headquarters last year and just fell in love with it. Killer overall tones, even at moderate volumes. I was impressed.

Even got to crank a jtm 45 for 10 minutes that same day. Fun!

[whitewave]

just to keep this topic active.
I love how it (seems to) sound

http://www.youtube.com/watch?v=DXok7Ujs_6Q

http://www.youtube.com/watch?v=CZAgQUWbw9A