PRS HDRX amp

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mark
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PRS HDRX amp

Post by mark » Fri Oct 14, 2022 11:51 pm

I remember when they came out I was somewhat amazed as it was posthumous amp, the concept didn’t sit well with me. Though you have to wonder if it’s a good amp regardless.

I was wondering if anyone has seen inside these amps and seen what separates them from the typical SLP Marshall?

Thanks for your assistance.

Mark

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Re: PRS HDRX amp

Post by daveweyer » Sun Oct 16, 2022 9:00 pm

I didn't know anything about it until Joe from the Jimi Hendrix Foundation called me. He was reading from the promo material which explained how PRS had been given one of Jimi's modded heads by Janie, to reverse engineer. Joe was surprised too because it seemed like it should have been Marshall itself who would produce an amp with "some" of my mods still left intact.
PRS seemed to be playing it safe by not making too many exaggerated claims, and I appreciated that. I think the amp they made had one tone stack tweak, but that was about all that had been left in Jimi's amp for them to reverse engineer.

It seems to me that they, or Janie, should have called me first if they wanted to build the actual Jimi mods in a newly produced replica amp; I could have at least given them some basics on where to start, and that would have made the amp a lot more authentic. I could have done this without giving away the farm either, so to speak. Still in all, it was nice to hear they mentioned me in their advertising, even if only to sell more amps.

So, are these amps really good, or just another wanna-be Jimi product??

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Re: PRS HDRX amp

Post by mark » Sun Oct 16, 2022 9:20 pm

Hi Dave

Thanks for your reply it’s quite helpful. I was aware of the tone stack mod, but not much else. I did read your thread and it was timely and in the end I couldn’t work out what Jimi was shooting for.

PRS mentioned mods to save the valves, though it might only be 1K screen resistors.

I haven’t heard the amp as there isn’t one locally available to try. I would be suspicious of any product which is Jimi in a box, though I liked Robert Keeley’s Monterey pedal. It’s a good taster that doesn’t break the bank.

I agree it’s unusual for PRS to be doing the amp instead of Marshall, though I suspect the demand must not be there for them to do it. Who knows?

Thanks again for your response.

Regards

Mark

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Re: PRS HDRX amp

Post by daveweyer » Sun Oct 16, 2022 10:38 pm

I'll go out on a limb here, but to answer what Jimi was shooting for, at least in the short term, one needs to look no further than the amp and fuzz that Mason Beckham has--that kit pretty well embodies what Jimi was shooting for in 1969 and 1970.
Beyond that, as far as anyone knows, he was shooting for the ideas he left in my notebook from West Coast Organ and Amp Service. He was trying some prototype circuits I made to help him work out where he wanted to go with his sound, and the guitar in general. I can say with some confidence that he wanted to hone the circuits he was using during the summer of 1970, but make a leap from there into new sounds and new music, which at that time were nascent visions and not fully developed.

This could be a whole new thread, and a long one, because it touches upon the unanswered questions of a lifetime.
I did not mean to begin a master class in speculative Jimi intentions and perceptions, just give you a short synopsis of what Jimi was likely shooting for.

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Re: PRS HDRX amp

Post by mark » Mon Oct 17, 2022 4:54 am

Thank you for your reply Dave. I’m not familiar with Mason Beckham, I did some searching and found his music but nothing about the gear he uses. Could you please tell me what he uses?

It’s quite mysterious what equipment Jimi used and if it was particularly instrument to his sound. He used a few different fuzz pedals and wah pedals vary with the different inductors. I have a Castledine board in a Crybaby (Halo inductor) which sounds quite Cream like while my Teese wah has a stack of dimes inductor which is different again. I have two Fuzz face clones which also sound very different.

Thanks for your assistance Dave.

Regards

Mark

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Re: PRS HDRX amp

Post by daveweyer » Mon Oct 17, 2022 9:40 am

I'll see if I can get Mason to post here and elaborate a little on his kit. Geoffrey Teese basically copied (arrived) at the same wah circuit I made for Jimi in 1969, even using 5089 transistors and some original Thomas inductors which he thought sounded best. There were some sonic differences though.
But the fuzz units were quite different from what people think Jimi had.

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Re: PRS HDRX amp

Post by masonbeckham » Tue Oct 18, 2022 6:49 pm

Hi Mark!

The amp and fuzz kit I use are what is discussed in the West Coast thread. Modded Marshall with 6550’s, Class B, 560v on the plates, etc. It’s a lengthy read now at this point but it’s so worth it! The fuzz is the unique circuit that Dave made for Jimi, the always on 3 transistor fuzz. With these together you will get any Jimi tone you could want from April of 1969 to September of 1970! (Especially Band of Gypsy’s)

The PRS amp has EL-34’s. I haven’t plugged into one, but from what I’ve heard it lacks a lot of clarity compared to the real mods Dave did. It’s kind of close, but every amp is kind of close when you’re going for Jimi. This is the real deal!

I assume the music you found was from our first album. I was using a vintage Dual Showman at the time. There will be new music with the West Coast rig very soon!

Mason

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Re: PRS HDRX amp

Post by VelvetGeorge » Wed Oct 19, 2022 11:31 am

Very cool Mason! Thanks for first-hand info as always Dave!

I agree, odd for PRS to be building a Hendrix amp. Very disconnected.

I guess we can discuss now that years ago Dave put people in contact with me about building some replica amps that would incorporate Dave's mods. After months of back and forth it fizzled out. What a shame. I figured it would surface elsewhere eventually, but would not have guessed it would be from PRS.

I've just announced my new version of the Super-Plex. The first channel is spot on JTM 45/100 tones. As soon as they are shipping I'll get one in the hands of someone who can do some Hendrix style clips.

https://store.metropoulos.net/collectio ... -watt-head
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Re: PRS HDRX amp

Post by daveweyer » Wed Oct 19, 2022 1:43 pm

Wow George, I did not know you were still building replica heads!! So good to see your post!
Let's do it now if you are still up for it and have got the energy.
I built one myself for Mason because I was tired of just talking about it and hearing everyone else do the same, and wanted to get an actual West Coast SL amp out into the world--I wanted real feedback from actual Jimi players who never quite got the sound they were hearing in their long studies of Jimi. (no matter what gear they were using or had tried)
Soon Julijan Eric will have one, and Xplorer too, because I sent them kits with all the right parts.These include the right transformers with the right regulation, and the right inductance for the output tubes, reverse engineered Stancor cores which fit perfectly in the old Dagnall bells.

I talked to Joe at the Hendrix Foundation yesterday, reminding him that any Jimi amps should start with a "Marshall" type head, since that is what everyone remembers and will accept. All the rest of Jimi's ideas can be implemented from that basis; Xplorer calls the new Jimi ideas the "Universe Series". I spent the last three years designing this stuff based on Jimi's notes in my West Coast notebooks, but Mason, Xplorer and others want to see the original 1969 and 1970 modded equipment become available first because that's the sound Jimi had at that point in his career.

So what do you think??

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Re: PRS HDRX amp

Post by mark » Thu Oct 20, 2022 3:48 am

Hi Dave

One question I haven’t asked is how many Marshall’s did you rebuild for Jimi?
I’m not sure I correctly understood the previous replies. Dave are you saying that you would like to see your incarnation of Jimi’s amp made by Marshall?
Marshall have already have made a Hendrix amp, I wonder if there is enough demand for another Hendrix amp?
I guess that would be up to the bean counters at Marshall.

https://www.creamcitymusic.com/2006-mar ... ull-stack/

It’s good to see forum members building clones of the Hendrix amp. Perhaps they can post clips and demonstrate the qualities of the amp and how it differs from the stock amp when they finish building their amps?

Hi Mason

Thanks for your reply. Sorry I didn’t reply earlier, I was hoping to read the West Coast thread again but time was against me.
I remember reading that Dave replaced the PI 12AX7 with a 12AT7 initially and given the AX7 (100) has a lot more gain than AT7 (60), even more so for the 5687 (16-21). The stock amp would break up more than the modded amp. I assume Jimi was one of the first guys to use the amp as an effects platform. How do you find it differs from a stock Marshall?

Regards

Mark

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Re: PRS HDRX amp

Post by VelvetGeorge » Thu Oct 20, 2022 11:23 am

Most of my current work is contract design and manufacturing for other companies. All under NDAs so I can't talk about it. Grueling work that runs me ragged. But it's keeping the lights on while I finish my own designs.

I have turned out a couple replica amps this year. A plexi 50 watt. And just recently a block end JTM 45:

https://youtu.be/kFLenKmrIxg

I have a new contract job in the works that leans heavily in the replica direction. But, like all this work, I can't discuss it.
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Re: PRS HDRX amp

Post by daveweyer » Thu Oct 20, 2022 1:48 pm

Well it's good to know you are busy. I thought that work had run you so ragged that you couldn't do replicas anymore.
Most of my work has been contract too, but it is not like my bills are being paid.

If you are interested in building a real West Coast Marshall, with all the original re-engineered components, just let me know. I don't have time to make them myself, that chapter was an earlier time. The Foundation is still interested in a larger scale production, but so many things have fallen by the wayside during these last couple years of the virus nonsense, and all that went along with that. Long story, we can email about that.

There was some interest in having Marshall itself produce the amps that Jimi actually used, but from what I have been able to gather, Janie and Marshall have had their problems, but Marshall still has some obligation to preserve the relationship--that precludes them from moving on any other Jimi related product. It just made a lot of sense for Marshall to be the company that produced a Jimi amp which embodied the circuits from West Coast. I think I have a copy of a letter I wrote to Jim Marshall many years ago advising him what I was doing and how the changes would preserve the amp--that would be the perfect fit for a retro amp introduction.

Mason's amp was actually a product authorized by Janie, the Super 100 replica, which was supposed to embody all the original elements of the amp, including Drake inductors. But wow, it was a long way off in sound and performance, as Mason will attest if he reads this post. I won't detail all of that here, but if players bought those amps hoping to capture Jimi's sound from 69 and 70, they were bound to be very disappointed. Logic would lead one to conclude that the PRS gambit was a new attempt to capture Jimi's actual sound from those years by actually copping some tweaks from West Coast, and it may be the case that Janie's relationship with PRS was on more friendly terms.

The conspiracy types imagine that the PRS affair was Janie's attempt to thwart the Foundation's effort to release a Jimi amp with all the West Coast circuits and designs, by getting product into the market first.

I don't really know, other than hearing Mason's amp and effects playing real Jimi music, and as long time valued forum member Revolver said when he heard it too, "That's it!!!"

My efforts on this forum have been to show the members how to do it, and to provide what information I can toward that end, notwithstanding all the earlier arguments about my authenticity and the reality of the West Coast experience. The PRS announcement pretty well ends any argument about the contentions of forum members that the whole story is just a farce--that those fights brought the forum down several times just seems silly now, because time has showed what really did happen.

As I mentioned, I rebuilt a Marshall replica into a real West Coast amp myself, just like in the old days, and sent it to Mason, just to get his response. I really couldn't have asked for more. It was a lot like hearing Bill's and Xplorer's and Shakti's efforts from their own builds, very affirmative.

So if someone wants to build real West Coast amps, to finally satisfy whatever market is left for the younger players who want to embrace Jimi as close a humanly possible, there is an opportunity. Who knows where it all goes?

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Re: PRS HDRX amp

Post by masonbeckham » Thu Oct 20, 2022 5:49 pm

Yes the 12AT7 cleans things up a little bit but there is plenty of gain available from the amp. It gets rid of the “buzzy” distortion and it’s more clear sounding.

Going off of memory and recordings of my JH100, it feels like a Tube Rectifier amp vs a Solid State Rectifier compared to the WC amp. There was a lot of “sag” in the JH100. It was quite trebly too, and the bass would get woofy when you added any in my case. I’d have it on 10 with a fuzz and notes would still die out and not sustain.

If you want early Hendrix, the JH100 will get you there “kind of”. I think there is better 45/100 style circuits out there. (Get one of George’s clones if you can find them!)

Comparing the WC amp to a clone of a 67 Superbass (El34’s) the Superbass sounds very 2D if that makes any sense. The WC amp sounds so huge! It is 100% pure Band of Gypsy’s on its own, the 3 transistor fuzz just enhances it and makes it shine even more!

It’s hard for me to describe this rig in words. The most simple way I can put it is compare Band of Gypsy’s to earlier Hendrix!

One thing to note is that you don’t lose any tone with this amp on a low volume. I’ve never experienced anything like it!

Mason

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Re: PRS HDRX amp

Post by daveweyer » Thu Oct 20, 2022 8:53 pm

Bear in mind that the 12AT7 was used for a larger purpose; the output tubes were run in Class B, meaning they were biased way down ro a few mils of current at idle, and with that much negative bias it takes more swing in the driver stage. It just so happened to improve the sound, not just by itself, but within the larger system and new operating parameters. Part of the sound is the output tubes running at a different operating point. See the 6550 thread....

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Re: PRS HDRX amp

Post by mark » Fri Oct 21, 2022 6:15 am

daveweyer wrote:
Thu Oct 20, 2022 8:53 pm
Bear in mind that the 12AT7 was used for a larger purpose; the output tubes were run in Class B, meaning they were biased way down ro a few mils of current at idle, and with that much negative bias it takes more swing in the driver stage. It just so happened to improve the sound, not just by itself, but within the larger system and new operating parameters. Part of the sound is the output tubes running at a different operating point. See the 6550 thread....
If the amp is running in class B does this mean that crossover distortion is clearly heard when it is clean and distorting?
So amps seem very forgiving of crossover distortion, though the 18 watt Marshall clones had some issues with crossover distortion and Paul Ruby came up with a clamping circuit to get rid of it.

The negative bias voltage on the 6550’s would have to be around -60VDC. I suppose the 12AT7 could provide enough drive to get the output stage grid to forward conduct.

I would love to hear comparisons recording between the Weyer amp and the Marshall.

Regards

Mark

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