Dickinson Schematic

[Ydna]

Hi, I've been looking into the Dickinson 45/100. First of all, does the sound change? I've been getting mixed info, either it adds "Voodoo vibes" or it doesn't do much at all. Second, I got the lay out of the dickinson amp, but I was wondering if anyone has a schematic for it. I searched the forums before posting this, and searched google, but I couldn't find a schematic.

[Brian Wallace]

I have one I did back in 07.

http://www.marstran.com/HendrixAmpMod.gif

[neikeel]

I have a copy of that schematic tucked away

One thing I am unsure of is the asterisked components. Are they there to suggest non-stock parts?

I would have thought that the 470R on the screens were stock for KT66 amp?
The asterisked 10k first decoupler is usually a 8k2 and the second 10k is added between the preamp filter cans (I presume that this era of amp would usually have been a 16uF or 22uF single).

Bits that are not asterisked are the 33k/560pF (is it a 560/500 or 470pF) and the 33k in the tone stack.

I think I will give this tone stack a try in on of my shared cathode 100watters but which one? The KT66 or EL34

[Flames1950]

Without digging through the photographic evidence I have, I think the Dickinson amp was the only 100-watt KT66 amp I could find evidence of with 470ohm screen resistors -- every other one where the printing was legible had 1K's. So it was probably questionable whether they were stock or not.

[VintageCharlie]

Neil, maybe this helps as motivation - here's a quote from Kindburro (G. Germino) of thegearpage (i quote it not because of the technical side, which everyone here knows, but because of the info regarding the tonal changes):

"So the JH stack is based on the single OPT version of the JTM-45/100 "Super Amplifier".......but with a couple of changes that members here on this thread have been kind enough to point out. Yes, the tone stack was changed to the later "lead" values of 500pf/33K slope resistor. This pushed the range where the tone controls operate specifically in the upper mids. It might even be thought of as brightening the amp up a bit. The original versions were pretty dark unless the Treble, Mid and Presence controls were spun up around 7 or 8. Even with this mod you still need to push the controls a bit to get out of darker territory. However with a strat it is pretty nice!
The other aspect of the JH amp that is not disclosed but is there for the astute eye to see is the pre-amp and tone stage are decoupled by a 10K resistor and each stage gets 32uf of filtering. This is pretty far from the two stages not being decoupled and sharing 16uf. This tightens things up and drops votage at the pre-amp slightly. It's a feel thing and does affect the sound as well.
[...]
The Monterey Classic as shown on my website does not have the Hendrix spec's incorporated. The last one I built, which Jerrod owns, we decided to utilized these component changes. I was very pleased with the results and thought it did remove some of the inherent dark character that has always been part of this circuit design. The decoupling of the tone and preamp stage was welcome also and gave a tightening feel/removed some softness seemingly adding a bit of clarity."

It's a quote from a big and informative post that can be found here: http://www.thegearpage.net/board/archiv ... 96965.html" onclick="window.open(this.href);return false;

This post that i found yesterday helped me decide, that i'll go with the Dickinson spec for my 45/100 build.

Hope it helps others too.

All the best,

VintageCharlie

[Ydna]

I figured instead of starting a whole new thread, I could ask in this thread, but could someone that has built a 45/100 give me a estimate of what it cost them? Even better, if you have built a Dickinson 45/100, and you can give me an estimate of price, that'd be great.

[neikeel]

The cost is the same as any basic Metro 100watter for either version.

If you add in NOS mustards/mullards/resistors you can spend shed loads or lots of time searching for parts at more sensible prices.

A basic alloy chassis with panels and boards (bare bones) kit was around $200 IIRC and the transformers are around $350 a set and the caps I guess is around 10-15 per cap and a board set of components and sozos less than $100? Add in a quad of KT66 and x3 decent 12AX7s. Head boxes are up to $300. I guess you are looking at $1000 for the parts plus more if you want to go as mad as Vintage charlie has done

I hope that George will have the store open again and will still be able to offer a range of amp kits and popular things like the bare bones kits and his transformers at prices that both make money and are not too expensive that people run away - not easy.

[Ydna]

Oh. Ok. For some reason when I totalled it with all new components in the metroamp store, it was in the ballpark of $1,700. And now I realized that that really doesn't make sense. If the Bare Bones 45/100 Kit is still offered, I'll buy that in the future sometime. I'm going Dickinson, but I'll buy all that stuff outside of Metroamp, because I don't think a few capacitors and resistors would help George profit. I'm going with all new, just because I'm a bit skeptical of the whole mustard cap thing. I heard the mixed clips, and not many people could tell the difference. An audience isn't going to notice a difference. NOS glass is understandable, but expensize. I have tons of NOS 12au7s, but no 12ax7s, which is a bit aggravating. So i'm looking at under 1,200 to put together a 45/100?

[Arclight]

You are missing the most important parts-the quad of GEC KT66's. Add another 800-1000 IF you can find a matched (reasonably) matched quad.

Just putting a pair into my JTM45 completely transformed the amp. The Gold Lions from Russia-made the bass much tighter-but there is no comparison with the real GEC's.

[Ydna]

I can't spend that much on glass. I know that is key to getting the sound perfect, because those handle higher B+ voltage, but how many people actually risk their NOS GECs for the higher B+ voltage. This amp would be for shows and such, I don't want to have a panic attack when I lose a 1,200 dollar amp, and 1,000 dollars of tubes.

[Arclight]

Why bother with all the other particular specs then? Although there aren't many venues where you could unleash THAT MUCH MARSHALL FURY Have you ever played through a 100watter?

[Ydna]

Yea. I've cranked a 100 watter out of a 4x12. With attenuation, it's manageable. I'm bothering with all the specs to get as close as possible, I just don't have money for NOS tubes. Besides, a 45/100 isn't as loud as a superlead. And if the band gets good, people wont mind if we play loud. I crank my Dual Showman Monday-Friday in the early afternoon normally. Nothing has been said to me, but my neighbor told my Dad it sounded good. Haha. Maybe he's just trying to figure out if it's coming from my house, then he'll steal the amp so he wont be annoyed? Who knows.

[Ydna]

Another question, and I thought I might as well use my thread again. Would it be possible with a switch to change the 45/100 to a Solid State rectified jtm45? I was thinking of having a switchable tone stack between dickinson and stock 45/100, using the standbyswitch as the switch, but that might be a bit too complicated.

[neikeel]

If it helps you a 45/100 is not as loud as the other superleads and probably puts out 80w clean, probably half as much again when fully cranked with a fuzz or similar.

You can probably get by with a 45/100 with a single 4x12 and an attenuator on -4dB.

I do not cane mine, I like it in the cleaner/break up zone (5-6) using a Strat with occasional pedal abuse. Although the amp is a clone it had NOS Mullard ECC83s and a very closely matched NOS quad of GEC KT66s.

My other 45/100 is an original block end which runs EL34s and has the extra preamp filtering that the Dickinson amp has but still uses the early tone stack.


Much more raunchy with more hair

I have gigged the KT66 amp a few times but generally use my 50watter with EL34s, having said that at our last outdoor gig I needed a 100watter with more clean headroom

[Ydna]

Gah. Those amps are beautiful. I don't even know where I would start for finding NOS GEC KT66s. They're hard to come by. If I get a job, I'll probably start the build in about a year. Long time away, but I have to be realistic. Yea, I'll be running an attenuator. I'll be making one myself as well. I'm about to aquire and restore a 70s bassman 50 with matching 2x12. Depending on the sound, I'll either sell it or keep it. I've heard of just the head selling for $800+. If I can do that, the amp could come much sooner.