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Garnet Pro sounds like shit - techs please help

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Re: Garnet Pro sounds like shit - techs please help

Postby biscuitdough on Wed Oct 28, 2015 10:45 am

Any news? I'm curious about this case, and these amps in general...
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Re: Garnet Pro sounds like shit - techs please help

Postby TylerSavage on Wed Oct 28, 2015 12:27 pm

I can't find my gut shots at all but I'm hoping to grab mine from my parents basement at christmas
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Re: Garnet Pro sounds like shit - techs please help

Postby llllllllllllllllllllllll on Wed Oct 28, 2015 2:40 pm

biscuitdough wrote:Any news? I'm curious about this case, and these amps in general...


Haha, well. I've got the flu and this:

Image

Bad roof leak during a rain last weekend. Everything is covered and moved to a dry area, getting in there with a wet vac and a razor today. It doesn't look like any of my amps were hit and I've pulled out everything I could fit in my Civic, so it'll probably be a few days before I try to turn any of my amps on, just in case they got wet.
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Re: Garnet Pro sounds like shit - techs please help

Postby biscuitdough on Thu Oct 29, 2015 12:31 pm

OOF. Good luck!
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Re: Garnet Pro sounds like shit - techs please help

Postby TylerSavage on Tue Oct 17, 2017 3:05 pm

Back on this as mentioned in the 'what's on it's way' thread. Can't help but feel this has to be a relatively easy fix.
The stringer on the 6JW8 schematic of a Pro :190 (LB190D in the garnet book) is in parallel with the tone stack, so coming in right after he first half of the first tube. So there could still be that crappy sound coming through but you're getting the added stinger circuit on top of it which, with that madness would more than compensate. (mine doesn't sound like yours there, yours sounds great.

So I'm coming back onto something shifting the bias of the first half of the first tube because it sounds like when I've screwed up a mod. The 100k resistor, 1.5k resistor or 25uf/25V cap would be my suspect

What makes it even more confusing to look at is the footswitch for the stinger is grounding the input of the stinger circuit, not actually taking the circuit out of the equation....
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Re: Garnet Pro sounds like shit - techs please help

Postby yard barf on Thu Oct 19, 2017 9:13 pm

Like FM TylerSavage, I am a huge fan of Garnet amps. I have a Garnet Pro with a stinger. If gut shots are of any help, I'd be happy to snap some pics of my amp with it's chassis pulled down.
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Re: Garnet Pro sounds like shit - techs please help

Postby TylerSavage on Thu Oct 19, 2017 11:15 pm

I'll snap some video of my pro and we can compare sound - mine has some ghost issues as well but it's definitely useable.

when I used to play actively in Canada a lot of people thought garnets sounded like shit - there were basements with corners full of them given to people by aunt's and uncles... almost every time I bought a garnet it had the original tubes, let alone he original electrolytics, 40 years later. I think they sounded so good for so long that no one took care of them or were willing to sell them until they gave up playing whereas they found their way into hands of people that didn't know any better. Eventually the Internet started correcting this
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Re: Garnet Pro sounds like shit - techs please help

Postby llllllllllllllllllllllll on Fri Oct 20, 2017 12:15 am

I hope it is something simple, but unfortunately I can't repair amps aside from speaker swaps and simple troubleshooting. Can't solder. So if anybody has any ideas I'm down to try something easy, otherwise I'm going to ship it out to Dr Balls once I get a couple things paid off. Unfortunately this thing saw four or five trips to two different techs, so I figured out pretty quickly that it needed to go to someone who knows what they're doing.
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Re: Garnet Pro sounds like shit - techs please help

Postby TylerSavage on Fri Oct 20, 2017 12:07 pm

Hmm, you could do that - or you can let us keep guessing and linking schematics for a couple years. Your choice I guess
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Re: Garnet Pro sounds like shit - techs please help

Postby llllllllllllllllllllllll on Fri Oct 20, 2017 3:30 pm

Oh hell yes. Don't let me get in the way!!
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Re: Garnet Pro sounds like shit - techs please help

Postby Dr Tony Balls on Thu Feb 08, 2018 2:29 pm

Anyone know what the impedance out should be on this Pro LB190 head? Me thinks its 4ohm but not terribly sure
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Re: Garnet Pro sounds like shit - techs please help

Postby llllllllllllllllllllllll on Thu Feb 08, 2018 2:57 pm

Yeah I think it’s 4 ohm.
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Re: Garnet Pro sounds like shit - techs please help

Postby yard barf on Thu Feb 08, 2018 5:37 pm

Dr Tony Balls wrote:Anyone know what the impedance out should be on this Pro LB190 head?


I own that same head. Pretty sure it's 4 ohms. I'll check when I'm home. Happy to provide gut shots or be of other service.
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Re: Garnet Pro sounds like shit - techs please help

Postby TylerSavage on Thu Feb 08, 2018 6:34 pm

4 ohms %100.

I brought mine with me to a jamspace last night - there was a jcm2000 already hooked up so I figured what the hell I'll just play that. Its nice to have contrasting perspective to your own stuff.
After one song I couldn't take it and plugged the Pro in and it was night and day better on every single front.
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Re: Garnet Pro sounds like shit - techs please help

Postby Dr Tony Balls on Fri Feb 09, 2018 2:56 pm

Update time: So upon recieving the amp its got a different problem then in the original post. Instead of sounding good for awhile and then sounding crummy, its barely putting out anything at all. Volume cranked and I can only barely hear it. Voltages in the preamp and power tubes look fine, but the phase inverter seems amiss with ~130V on the grids and close to 200V on the cathodes. I dont keep a spare 6SN7 around so i've gotta order one before I can continue checking it out. The original issue could be related or maybe not...time will tell. The amp was also biased far too hot which could have played into things.

General thoughts:I have never previously looked into Garnet circuits but the basic circuit on this one is cool, and very similar to what I have done on the Balls Twenty and Hundo. Bax stack with a LTPI...pretty cool. The "stinger" function I havent really messed with yet, but the implementation of it is bonkers to me. I have no idea why you'd put a gain stage in parallel with the tone stack. Seems like it would be killer as a front end pentode booster instead (and ive thought about doing the same thing on some amps myself).

Another thing I cant wrap my head around is the 6SN7 phase inverter. I've been using the schematic below which matches the amp pretty damn close and shows a 12AX7 phase inverter, which is pretty common. The 6SN7 is a LOT lower gain than that though, and seems like you could go with a higher gain tube. Maybe.

http://www.thetubestore.com/lib/thetube ... 0D-PRO.pdf

Also, the amp uses 2 12AX7s in the preamp and only uses HALF of each tube! WTF!
Last edited by Dr Tony Balls on Thu Mar 01, 2018 9:43 am, edited 1 time in total.
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Re: Garnet Pro sounds like shit - techs please help

Postby llllllllllllllllllllllll on Fri Feb 09, 2018 3:25 pm

Ah shit, that sucks. If it helps I hooked it up to a different four ohm cab before I shipped it out and it had the same old problem as before. Sounded good at first but after a while (say 20 min after playing it with the vol knob up a little past half way) it did that spitty sound it did before.
I was even wondering why I never used the pull boost switches before, but I didn’t mess with the Stinger. Didn’t want to test the 1x12 I was playing it through. Wonder if something else got fucked up in transit.
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Re: Garnet Pro sounds like shit - techs please help

Postby TylerSavage on Fri Feb 09, 2018 10:15 pm

Let me know if you need anything Dr. I have the Garnet book with every schematic on my desk at work, can scan things monday
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Re: Garnet Pro sounds like shit - techs please help

Postby Dr Tony Balls on Thu Mar 01, 2018 1:42 pm

Turns out the problem where i was getting no power out was user error (doh). Working great just cant yet get it to make the original problem. Gonna reset the bias as hot as it was when i got it and see if that changes anything.
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Re: Garnet Pro sounds like shit - techs please help

Postby TylerSavage on Thu Mar 01, 2018 4:58 pm

I still don't know why exactly the 6SN7 was used in the pro considering the 6SL7 was in the Rebel series.. because the preamp isn't generating an insane amount of gain anyway.

Go figure when I started googling I just run into my own topics: https://www.guitarscanada.com/index.php ... sl7.37755/
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Re: Garnet Pro sounds like shit - techs please help

Postby biscuitdough on Sat Mar 03, 2018 12:19 am

Dr Tony Balls wrote:Update time: So upon recieving the amp its got a different problem then in the original post. Instead of sounding good for awhile and then sounding crummy, its barely putting out anything at all. Volume cranked and I can only barely hear it. Voltages in the preamp and power tubes look fine, but the phase inverter seems amiss with ~130V on the grids and close to 200V on the cathodes. I dont keep a spare 6SN7 around so i've gotta order one before I can continue checking it out. The original issue could be related or maybe not...time will tell. The amp was also biased far too hot which could have played into things.

General thoughts:I have never previously looked into Garnet circuits but the basic circuit on this one is cool, and very similar to what I have done on the Balls Twenty and Hundo. Bax stack with a LTPI...pretty cool. The "stinger" function I havent really messed with yet, but the implementation of it is bonkers to me. I have no idea why you'd put a gain stage in parallel with the tone stack. Seems like it would be killer as a front end pentode booster instead (and ive thought about doing the same thing on some amps myself).

Another thing I cant wrap my head around is the 6SN7 phase inverter. I've been using the schematic below which matches the amp pretty damn close and shows a 12AX7 phase inverter, which is pretty common. The 6SN7 is a LOT lower gain than that though, and seems like you could go with a higher gain tube. Maybe.

http://www.thetubestore.com/lib/thetube ... 0D-PRO.pdf

Also, the amp uses 2 12AX7s in the preamp and only uses HALF of each tube! WTF!


The schematics I was looking at showed a transformer phase inverter with 6SN7 driver for the BTO. The Pro I'm looking at has a preamp 12AX7, 6JW8 fuzz and tremolo, 12AX7 phase inverter.

It seems that the description of the Pro as a half-power BTO is either incorrect, or there were multiple designs for each that differed in key aspects.

BTO with no preamp/drive

Pro, 2 pages
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