Friedman JJ 100w gut shots

Mourguitars

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It was Biased real cold technomancer 25mA

Plate voyage was 452 i do believe so about 32mA with the bias calculator ..having a bit of problem here

2 tubes were Biased at 25mA
One was 23 mA..thats ok but ...
4th tube was reading 16mA

I tried 4 sets of brand new quads i have and on one tube im getting a real low number of about 8 mA

Got to do some reading....but somethings off

Took the Mullards i had in my Ceriatone 800 those are with in 2.5mA between all 4 in that quad...still had that reading on that one socket of 7.3 mA lower than the other 3

Socket is the last one from left to right next to the single 12ax7 im getting a bad reading on

Mike
 

technomancer

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That is odd for it to be off that much if it isn't the tube (which it obviously isn't). Shoot an email to [email protected] and Dave will get back to you (at least he always has with me, even with stuff not directly about his amps).
 

Mourguitars

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Thank you technomancer !

Just sent a email..thanks for that

From what ive been reading some people dont mind 10mA off..they like it as long as it dont hum..odd

Remember the days when a tube went..put a new one in and crank and rock out !

If it glows it goes...!

Mike
 

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Dave emailed back very quickly and told me to check the voltage again it should be higher and use a variac set to 120

Fired up the Variac at 120..checked plate voltage came up on all pins 479.8

Dave said voltage should be 470 ish...

Set bias at 32 , Calculator said 31.26 and had these reading below..Dave said set amp at 32mA
31.9
30.7
9.5
12.3

Ok...wtf moment

I moved the right pair of tubes over to the left and left pair to the right and got these readings
32
29.9
31.2
31.8

ok what just happened....left on 30 mins, played made some noise for about 20 mins....it drifted up to 33.2 and i set it back to 32 ...now tubes are within 2-3 mA of each other

I like this Bias Master...but it reads different even with amps with bias points with a good Fluke meter

I think everything is fine as of now still on same readings but i think these leads on this Bias master are cheap , this thing is that accurate ...i dont know , its getting the side eye from me now

Going to recheck in the am....

Mike

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technomancer

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Yeah definitely could be the probe. Sounds like all is good though which is the important thing.

I always really liked the JJ circuit, the BE channel on it with the JBE off is a blast. I found myself wishing it had a touch more gain that way though so I built one with added HBE channel and the full Deluxe-style NFB controls. It's one of my most played amps.

Dave is awesome, literally one of the most helpful guys I have ever dealt with.
 

Mourguitars

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Yeah definitely could be the probe. Sounds like all is good though which is the important thing.

I always really liked the JJ circuit, the BE channel on it with the JBE off is a blast. I found myself wishing it had a touch more gain that way though so I built one with added HBE channel and the full Deluxe-style NFB controls. It's one of my most played amps.

Dave is awesome, literally one of the most helpful guys I have ever dealt with.


Awesome on you amp and yes..Dave is very helpful , i wonder if he has any free time..hard working guy for sure !

I bought this Bias tester off Amazon...it will be here friday and quickest one i could get delivered here the fastest

Ill recheck the amp then..again ! Just want to make sure..my peace of mind

61fqH9U5phL._AC_SL1220_.jpeg


Just another tool..hope it works out and i like tools ...you should see my Snap-On box !

Mike
 

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How's the reliability of those amplifiers? I see a bunch of no-noes in there.

As in neotronic ?

Other than the piggy back caps im sure were tweaks made to Jerry's taste..other than some solder flux here and there that should have been cleaned ...easy to change parts and work on is what im happy with

I think on Tony Mackenzie vid on the JJ jr there was a nest of resistors , i think it was on that vid..but Randy from Phaez amps does that..and there is no way anyone could service that Pheaz amp i have but Randy

I havent heard or read anything negative about any issues with Friedman amps..some of TGP guys dont like how tight feeling they are and compressed ...but they mostly play Classic rock and blues over there it seems mid gain stuff or pedal platforms

Man, Dave answers emails back quick..and you talk to him...i like that if there is ever a issue....

Thats a big Plus !!!

Hey Shask.....if you are reading this , how hard would it be to build a box with a 4 way rotary switch with the Bias probes with 4 inputs with these mini plugs in on that bias thing i just bought ..and have a out jack with banana plugs going to my Fluke meter to test the bias with...possible ?

I know you can buy a single Bias plug to fit with you meter..i have 4 Good meters ..just trying some new ideas to make my life a little simpler and build something new ...lol

Mike
 

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Ok , this Bias meter was dead on with with my last set of TAD meters readings

All is good...time to button up and play and check out the Friedman loop today !

Those bias wire's on that TAD....i still dont trust them or have something off in the octal socket itself

Mike

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I've owned 3 with no problems and haven't seen a lot of problems across multiple online groups.

I'm curious to hear what you consider "no-noes"

Preface:
The reason I am asking is not to bash on the amp/maker. I am just wondering which of the theoretical problems are actually non-issue on an amp in normal use. Given the responses I've got, it looks like all's fine.

What I consider a no-no (it all comes down to vibration):
* radial electrolytic caps used in place of axials: if there's vibration, the base doesn't work as support against lateral loads - it's just the leads that take up the load. The caps weren't designed to handle it.
* the radial film caps - the same problem as above and on top of it if the lead is bent right next to the body of a cap the resin can crack - moisture might creep in over time which would lead to capacity drift and dc leakage
* components supported by one lead, the other end hanging in free air, soldered to a wire
* components, especially relatively heavy film caps hanging on very long leads
* sharp bends on single core wires
 

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This JJ doesn't need a boost at all but , the last few days playing it with different cabs and boosting the front in a little...i like to boost amps..im loving it

Seems it likes TS9s -808s and my TS7 (the sleeper ) the best over my Centura and SD-1 and a Cab with T75/V30s its a ..well a Friedman !

Cab with ReaperHP/Retro30 that sounds great with my 800 was a tad bright but could be dialed out

I might put 2 greenbacks in my Avatar 2x12 and put on top of the Friedman cab to check out but i wanna get so play time in this weekend...this amp likes V30s tho

Im running a Flashback Delay with a Doug Aldrich tone print for a rhythm delay...with a Les Paul its a pure tone machine...and i like the stock pickups in both LP's i bought...they sound righteous with my Rack and Ceriatone 800 as well

I took out the original 12AX7s...they were JJ's , Dave had 2 x12AX7 and 2x 7025 and i put the EHX Pre's in and there 7025's...didnt tell much sound wise but next time i have it on the bench i may swap out the 7025's with some old glass i have. or maybe all old glass....but it seems these amps from what i read like the NP tubes

Mike

BTW ...i did find out i have a short on one pair of leads from the TAD BM...I like the cheap one from Amazon tho and will get new set for the TAD....man, that thing about gave me a heart attack with the low reading...its brand new ...things happen !
 

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Preface:
The reason I am asking is not to bash on the amp/maker. I am just wondering which of the theoretical problems are actually non-issue on an amp in normal use. Given the responses I've got, it looks like all's fine.

What I consider a no-no (it all comes down to vibration):
* radial electrolytic caps used in place of axials: if there's vibration, the base doesn't work as support against lateral loads - it's just the leads that take up the load. The caps weren't designed to handle it.
* the radial film caps - the same problem as above and on top of it if the lead is bent right next to the body of a cap the resin can crack - moisture might creep in over time which would lead to capacity drift and dc leakage
* components supported by one lead, the other end hanging in free air, soldered to a wire
* components, especially relatively heavy film caps hanging on very long leads
* sharp bends on single core wires

In all seriousness none of those are anything I would actually worry about (nor have I seen anybody else concerned). What I'd consider the final word is Cantrell and Steve Stevens have been touring with these amps for years with zero issues. :shrug:

Also wiring is stranded not solid core so definitely not an issue. Generally anyone that isn't clueless will not use solid core wire in amps because it can get breaks in it way too easily.

To be fair I have never see a turret or hybrid amp that was built following actual mil-spec construction and solderinng... everybody does their leads "wrong" for strain relief etc etc etc
 

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In all seriousness none of those are anything I would actually worry about (nor have I seen anybody else concerned). What I'd consider the final word is Cantrell and Steve Stevens have been touring with these amps for years with zero issues. :shrug:
Awesome, thanks! :yesway:

Also wiring is stranded not solid core so definitely not an issue. Generally anyone that isn't clueless will not use solid core wire in amps because it can get breaks in it way too easily.
Components do (I should have used the word "leads" instead of wires).

To be fair I have never see a turret or hybrid amp that was built following actual mil-spec construction and solderinng... everybody does their leads "wrong" for strain relief etc etc etc
Yeah, in military if things fail, people die, often a lot of them. While a guitar amp is a different story. The conditions the equipment is used in is different too... Both the engineering and market prices reflect it.
 

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Awesome, thanks! :yesway:


Components do (I should have used the word "leads" instead of wires).


Yeah, in military if things fail, people die, often a lot of them. While a guitar amp is a different story. The conditions the equipment is used in is different too... Both the engineering and market prices reflect it.

Yeah while eliminating all of the things you mentioned would make it more durable, they are pretty much things all turret / hybrid based amps have in common and not typically an issue in a guitar amp. If it was an aircraft with much more vibration and motion related stresses different story.
 

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I think on Five Watt World i thought i heard that Ken Fisher on his Trainwreck amps used solid core wiring...i wonder what his reasoning was , yes, it will stay where ya lay it and maybe looks cleaner to some ...but stranded is more pliable and most likely be more durable being the industry standard

Mike
 

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I think on Five Watt World i thought i heard that Ken Fisher on his Trainwreck amps used solid core wiring...i wonder what his reasoning was , yes, it will stay where ya lay it and maybe looks cleaner to some ...but stranded is more pliable and most likely be more durable being the industry standard

Mike

Use teflon insulated stranded, best of both worlds. You just need sharp wire cutters to strip it cleanly.
 


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