bradm
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Post by bradm on Oct 26, 2020 20:14:34 GMT -7
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Post by pcns on Oct 26, 2020 20:41:06 GMT -7
Just the prototypes had the switch. I loved the EL34's in that amp, it had a great roar to it when you cranked it up!!
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bradm
Junior Member
Posts: 74
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Post by bradm on Oct 26, 2020 20:46:43 GMT -7
Just the prototypes had the switch. I loved the EL34's in that amp, it had a great roar to it when you cranked it up!! Thanks, good to know! And, I remember running it through it's paces two years ago. Client had me remove the KT's and pop in some EL34's ...sweet amp tones for sure!!! (Reminds me of the old '72 Orange 120watt head I had in 1977...it rocked...well, when on 10!!!
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Post by pcns on Oct 27, 2020 5:15:09 GMT -7
Just the prototypes had the switch. I loved the EL34's in that amp, it had a great roar to it when you cranked it up!! Thanks, good to know! And, I remember running it through it's paces two years ago. Client had me remove the KT's and pop in some EL34's ...sweet amp tones for sure!!! (Reminds me of the old '72 Orange 120watt head I had in 1977...it rocked...well, when on 10!!! awesome amp and as Dr Z said when it was released "you'll need your big boy pants" with this amp because it likes to be cranked!!!
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Post by Jaguarguy (Mike) on Oct 27, 2020 15:31:59 GMT -7
Congrats! Here's some background on the amp for you. There were six of the prototypes made - I have prototype #1. I believe #2 was with David Holt for a while. Here's a video of him demo'ing the amp.
When I spoke with Doc, he mentioned one of the reasons that the EL84/switching never came out was that people preferred the KT66s. Change resulted in less complexity and cost. I keep mine on the KT66 set-up - I just like the sound of the KT66s better.
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bradm
Junior Member
Posts: 74
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Post by bradm on Oct 28, 2020 18:37:27 GMT -7
Congrats! Here's some background on the amp for you. There were six of the prototypes made - I have prototype #1. I believe #2 was with David Holt for a while. Here's a video of him demo'ing the amp. When I spoke with Doc, he mentioned one of the reasons that the EL84/switching never came out was that people preferred the KT66s. Change resulted in less complexity and cost. I keep mine on the KT66 set-up - I just like the sound of the KT66s better. I saw that, Mike. Noting he has the finished product with the 'Antidote' faceplate. I thought I saw a Youtube video somewhere of David with this particular amp...will have to scour. If anyone is interested, I may be letting this go along with a Mesa cab. Will post appropriately if I do. For now, I have a pair of Gold Lion KT66's I want to pop into it and check out the tones. I am really torn between the two tube sets at the moment. LOVE being able to bias for either set of tubes and just flip a switch. I know the EL34's in it (I think Mullard Reissues) are ok for now. KT's are intriguing.
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Post by Jaguarguy (Mike) on Oct 28, 2020 18:52:01 GMT -7
I think this may be the exact amp
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bradm
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Posts: 74
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Post by bradm on Oct 28, 2020 19:36:27 GMT -7
I think this may be the exact amp Hahahahaha! I was JUST about to post the same! Yes, it is! "Beat me to the punch!" But, the very next year...same location...he has the production amp...note the faceplate (below). David Holt live
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Post by Jaguarguy (Mike) on Oct 30, 2020 6:38:51 GMT -7
I never updated my faceplate - kinda like the "Special Design" name.
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bradm
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Posts: 74
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Post by bradm on Oct 30, 2020 10:55:34 GMT -7
I never updated my faceplate - kinda like the "Special Design" name. He didn't either. Wonder how that worked out...whether it was swapped for a current model, or the final production version sent...? I certainly won't do it.
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bradm
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Posts: 74
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Post by bradm on Nov 10, 2020 13:14:46 GMT -7
Well, this head has my mind spinning. Maybe not in a good way...or, maybe in an awesome way! Ya never know until you venture out, right??
So, I was searching on info for a specific amp demo and the Doc's video on the idea behind the Antidote pops up in the YouTuber list. I'd seen it before, but stopped to watch. Now, mind you...this time watching I had just finished restoring a '78 Marshall 100W Master for a client. I restored it with three exceptions. I used a 120pF silver mica for the bright cap (that lets "just the right amount" of high frequency harmonics through when the volume control isn't maxed. Some clip it and fight not enough top end glassiness.) And, I used metal oxide resistors for the front (jack mounted) input resistors. That greatly reduces entry level hiss which, in turn, gets amplified by successive stages.
Now, Doc said the amp was loosely based on a JTM45. And, he goes on to explain the that, instead of the 4 hole Marshall variety where folks jumper channels together...he tied them together internally. That was all I had to hear and I started pulling out schematics and comparing notes. (A LOT of Marshalls in that era shared the same (or similar) output sections.
Well, after finishing the 2203 Marshall...the gain stage was amazing. Best master-controlled amp I've plugged into in a long time. Then I realized that...it would not take much to change a JTM45 style input to a 2203 style cascading input for more gain. To do that, you open up the parallel tie of the channels. Yeah, you likely see where I'm going with this.
So, it's a Special Design...a prototype...and, I'm a tinkerer SO LONG AS I do not have to drill holes...and...can revert an amp entirely back to stock in an hour.
Here's the idea: Open the channel binding...replace the vintage/modern switch with a 4PDT switch to enable Antidote mode...or flip the switch for 2203 mode. The foot switched tone stack lift stays as-is for a nice boost. The HI volume is what it does best. And, the NORM volume is now your NORMal volume control or...inserted after the Treble wiper to be a typical 2203 master volume.
What might've complicated this further is that the original JTM45 stage1 for both channels shared the same cathode resistor||cap network...Doc's already broken that out separate for an easy conversion. I've not drawn this out yet, but I "think" 4PDT toggle can pull it off. If I find I need additional switching, I'll forego any relay complications and minimize what the switched mode actually does...likely chosing the HI channel of the Antidote and foregoing the Norm.
The cool part is...no holes drilled...and reversing it all is very simple if it doesn't yield the result. But, after seeing Doc's remark on not adding a PPIMV due to isolation complexity at the insertion point...one added stage from a rewire just might make for the best of both worlds. Any of y'all ever goosed the Antidote that way?
brad
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bradm
Junior Member
Posts: 74
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Post by bradm on Dec 24, 2020 21:57:22 GMT -7
Well, I threatened to do this back in November and, tonight, I finally did it. The prototype is now a 'prototype, new edition'! I knew I had to open it up and do a little maintenance, so I got a little radical. Here's the story: With steel & aluminum showing a bit of oxidation over time and hum invading, I had to get into this Antidote and care for it. But, as it was a prototype, it had the EL34/KT66 switch. Well, EL34''s were in it, so I took it over to Gold Lion KT66's. Welllll...since I was in there, a loosely designed JTM45 (which doc noted on a video) really isn't too far from a Marshall 2203 master volume circuit (a fave of mine). As this amp is a well-built keeper...I just couldn't help it. It took just a few hours to convert it to 2203 specs...sort of. Kept KT66's...cool choice with this circuit! Then there's the HI & NORM volumes. The HI became the 'Volume' and the 'NORM' became the Pre-PI master right after the tone stack. The extra series gain stage was exactly what I was looking for. Some typical pot/jack/chassis cleaning resolved all the residual low level hum and this amp now rocks to suit my tastes!!! And. per typical Dr. Z specs, it's a rugged version of it's now-ancient predecessor! Might have some sound samples to come this winter. Cheers! Brad
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Post by j4gitr (John) on Dec 25, 2020 3:44:34 GMT -7
The Antidote was one of my favorite amps, but it was just too loud for me. Sounds like you’ve found a way to enjoy all its glory responsibly. Congrats.
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bradm
Junior Member
Posts: 74
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Post by bradm on Dec 25, 2020 11:13:40 GMT -7
I sure did! And, yes, it still gets pretty loud, but having the master in there really let's you enjoy some madness and STILL hear!
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bradm
Junior Member
Posts: 74
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Post by bradm on Jan 2, 2021 16:28:38 GMT -7
Not only did the Antidote prototype get a new tone...it got a slight facelift! A friend found a valence by Harvey and it made my day when installed today. Love it!
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bradm
Junior Member
Posts: 74
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Post by bradm on Jan 16, 2021 21:42:04 GMT -7
This is the pot settings for the sound clip soon to follow. Keep in mind the 'High' channel is analogous to Volume and the 'Norm' channel control is now a master volume as it was converted to a single channel amp. (i.e. quasi-2203). Here's the setup for the clip: Late-model Les Paul with 1966 Gibson humbuckers installed...straight into the amp...no added flavor. The "Volume" is at 10...the "Master" (i.e. old Normal channel) is between 2-3 somewhere. KT66's are still in the amp. More video of the clean/dialed-back tones to come later. Changes involved separating the first two stages and cascade them, metal film 68K & 1M resistors at the front end to reduce hiss contribution when pushing the preamp. (Same with the signal path 470K resistors in the successive stages.) The vintage/modern switch and the tone stack footswitch lift circuit remained intact and as the Doc designed. Why did I do this? I'm not a huge JTM45 fan, but this head is everything aesthetically I love and Doc builds solid amps made for the road. I just wanted a pushed tone at lower levels and the 2203 circuit is where I wanted to take it. After all...this is a prototype...right???
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Post by runninwiththerevil (Matthew) on Jan 27, 2021 20:07:42 GMT -7
Dang that looks and sounds great.
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bradm
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Posts: 74
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Post by bradm on Jan 29, 2021 11:54:43 GMT -7
Dang that looks and sounds great. Thanks, Matthew! It gets better...a purple leather handle with cream stitching arrives tomorrow from Brookwood Leather to round out the look. (I was hoping to do cream with purple stitching, but his cream leather wasn't up to par for the weight of a head.) I gotta make time to do some clean demos. It was at a friend's house being tested with cabs. Just got it back and looking to have fun with it now.
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bradm
Junior Member
Posts: 74
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Post by bradm on Jul 13, 2021 21:09:42 GMT -7
Final shot of the rig altogether. Had ordered a Mojo Canyon cab, 1x12 @ Marshall 1936 specs and dropped an Eminence CV75, 16 ohm into it. The cab has a front facing port so the speaker breathes really well. The guitar is an '07 PRS Singlecut Satin with 57/08's in it. Paired with the Z and that cab, it's a fun, LOUD, yet very small rig. The only caveat I ran into is that "Fender Rough Blonde" has changed colors a little over the course of time. The cab is the newest "version"...I prefer the version Doc used on the head. Finding it is a bear. On a stage, you'd never know it. The very last addition to the head was some custom purple knobs (didn't photograph correct). Were also made using a fluorescent dye and will really pop under a blacklight. Better sound samples coming soon...
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Post by Mark (Basement Enthusiast) on Jul 14, 2021 7:25:45 GMT -7
That PRS is siiiiiiickkk!!!
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bradm
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Posts: 74
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Post by bradm on Jul 14, 2021 20:39:17 GMT -7
Thanks, Mark! I definitely agree! It has that 'Fat/wide' profile which is their take on the '57 Les Paul neck. One thick slab of mahogany and it rings for days. The big plus??? At 8 lbs or slightly less, it's really easy on the shoulder (super important for us old guys!!!). Doc's build on that head dimension was stellar. Perfect size, weight and yet some beefy transformers to make quite a little monster amp platform.
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Post by Mark (Basement Enthusiast) on Jul 15, 2021 6:15:10 GMT -7
Thanks, Mark! I definitely agree! It has that 'Fat/wide' profile which is their take on the '57 Les Paul neck. One thick slab of mahogany and it rings for days. The big plus??? At 8 lbs or slightly less, it's really easy on the shoulder (super important for us old guys!!!). Doc's build on that head dimension was stellar. Perfect size, weight and yet some beefy transformers to make quite a little monster amp platform. Agreed--PRS singlecuts can tend to get a little heavy, so 8 lbs. or below is pretty remarkable. I've got (among other PRS's) an ~8.5 lb. Stripped '58 with 57/08 pickups and the wide-fat neck, as well. That guitar is a beast in the best way possible.
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Post by captainron (Ron) on Aug 8, 2021 7:17:12 GMT -7
Congrats on a fantastic amp! Dang I want one!
Ron
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bradm
Junior Member
Posts: 74
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Post by bradm on Aug 11, 2021 20:29:10 GMT -7
Thanks, Ron! It's been a work in progress. Likely the closest Z stock amp I've ever had to match tone would've been the Galaxie head I had. I didn't know how good it sounded until the day I swapped it. I thought...well, I'd better pop a footswitch in to test the jack. Then I found out what I'd WISHED I'd known...that you needed the footswitch to pop in the gain-side. I would've called off the deal, but got an amazing trade weighted in my direction. Lol, they knew what they were getting.
This particular amp was fun to continue the "prototype" adventure the amp started life with. Knowing all along that it's a simple swap back to stock if someone prefers JTM45-ville. It is, as all Doc's amp builds are, just a beast of a platform. As an samp tech, I absolutely love the simplicity and straightforward builds Mike does. Makes for a solid touring amp and a beauty to repair when needed...and, if you know your stuff, no schematic needed.
Brad
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Post by rickc007 on Aug 18, 2021 6:36:33 GMT -7
Just came across this thread. This amp has really been put to good use.
I was the second owner, traded David Holt a Fender Vibroverb for it. Watched him play it a bazillion times in Austin. He made it sound great live, but I was smitten with it clean in my house. JTM45 is probably my favorite tone I had this the same time as a Germino Classic 45, and Fender Bassman Each a thing of beauty
Congrats on getting this rare beast, and glad you're having fun with it
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bradm
Junior Member
Posts: 74
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Post by bradm on Aug 18, 2021 20:13:59 GMT -7
[Just came across this thread. This amp has really been put to good use. I was the second owner, traded David Holt a Fender Vibroverb for it. Watched him play it a bazillion times in Austin. He made it sound great live, but I was smitten with it clean in my house. JTM45 is probably my favorite tone I had this the same time as a Germino Classic 45, and Fender Bassman Each a thing of beauty Congrats on getting this rare beast, and glad you're having fun with it] Thanks for commenting! I love documenting the history on pieces I've owned through the years. Swapped a Vibroverb for it, eh? So, from you...where'd the amp end up? On a rather funny note. I'd added David as a friend in Facebook and sent him a photo of the amp's transitions I've taken it through. His response about this particular one?? "I'm not missing it!" (As he posted back a photo of his current Two Rock! LOL!!!) As for the amp now, I'm presently rolling through some preamp tubes to see what subtle tweaks I can concur up. Just popped a few long plate ECC803's in it...awaiting a clear hour or two to embark on cranking it a little above the norm. Appreciate the comments about it! Add more if you recall! I'm down here in SW Ohio if you happen to be close to the area. Brad
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bradm
Junior Member
Posts: 74
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Post by bradm on Sept 25, 2021 12:51:01 GMT -7
All, here is a clip, albeit poor quality & playing, of the Antidote prototype after modding it to '78 2203 specs and then adding a typical S.I.R "30-something" gain stage between V1b and V2a and inserted via the Vintage/Modern switch. The playing was done cold and I really didn't have the ideal mic setup to do this. The audio does NOT do the tone justice. All the tone you hear is at a comfortable room level. Remember, HI is the gain volume...NORMAL is the Master (in typical Marshall style of Pre-PI).
For you that don't want the historical review of my mods...the audio starts right about 5 min in.
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