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Dirk, a HRD/GB is a different type circuit than a DRRI, PRRI, or a Twin that uses a 12AT7 in the phase inverter V3 position. Now you have the wrong plate voltage feeding your power tubes hence your bias adjusting is hindered.
You need some type of 12AX7 balanced tube for V3 for proper voltage into your power tubes. The very best sounding IMO is a Genelex Gold Lion gold pin or a Sovtek 12AX7LPS though they are long plate triodes they won't last as long but the tone is clean and very warm. A short plate will last longer but not sound as sweet IMO. If you don't has a balanced tube in V3 you will have different voltages going into your 2 power tubes. Not good and you cannot get a proper bias.
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04-13-2016 12:17 PM
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List of tubes i just bought for my HRD GB
V1:JJ 5751 (~ ECC83) JJ Electronic this one was only 10 euros don't know why i saw a NOS but that was 40 is there significant difference ?
V2: EH 12AY7 / 6072A Electro Harmonix
V3: Sovtek 12AX7LPS / ECC83 Balance-Selection for double triodes
Powertubes: 6L6GC-STR RCA-Style black-plate TAD PREMIUM Selected, Pair (2 matched tubes) good choise ??
When the tubes get here i will bias the amp as Vinny says at 68 (if i get the courage to do it my self ) and sample a before and after comparison,
It seems strange to me that a nearly new (the guy i bought it from used it 2 times) amplifier will have that kind of problem., and one has to install a rubber pad on the tubes to get it solved. wouldnt it dampen the tone ?
thanks everybody.
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Great choice reefer. If you can get a NOS 5751 they are wonderfully great sounding and worth the high price. Yes those rubber dampners also dampen tone. With good tubes and a proper bias you shouldn't need them. I consider them a bandaid fix. LOL
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Just swapped the tubes in the amp and I'm getting a weird electricity noise coming from the back of the amp also the power tubes are glowing blue
Inviato dal mio iPhone utilizzando TapatalkLast edited by reefer_man; 04-18-2016 at 01:53 PM.
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There's also a plastic cover in v3 not sure if that is blocking the tube from getting all the way in .. It isn't glowing as the others do
Inviato dal mio iPhone utilizzando TapatalkLast edited by reefer_man; 04-18-2016 at 01:57 PM.
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Inviato dal mio iPhone utilizzando Tapatalk
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Rattle went away and sound is much much better.
Inviato dal mio iPhone utilizzando TLast edited by reefer_man; 04-18-2016 at 01:58 PM.
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The round blue screw is your bias adjustment.
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Thanks vinny does the v3 tube has to glow like the others?
Inviato dal mio iPhone utilizzando Tapatalk
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Originally Posted by reefer_man
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All fixed amp no longer rattles ( I removed the cage around the power tubes ) It sounds much much better with the new tubes and proper bias which I settled at 67 . Special thanks to vinny for helping
Inviato dal mio iPhone utilizzando Tapatalk
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Are you still using one ? Favorite tone settings to emulate a Tweed vs Black Face sound ? Input 1 vs Input 2 and tube choices ?
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yup, I still have it and still use it.. I have a number of amps. DV little mark jazz, fender blues jr.. and the george B... for jazz the g.b rules. my settings depend on the guitar.. I have a gibson l-5 wesmo,, the new ES-275, and a crimson ed. BBking..
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I am curious about your settings for the WesMo. For chord-melody for instance.
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I am new to this forum but have gleaned a lot of very good information about the George benson hrd. I found a brand new amp for a very good price and finally pulled the trigger. I'm really looking forward to getting it. I'm pretty comfortable with tube gear so making adjustments to the GB is not to daunting to me. I'm just a hobby player but really enjoy playing. I've been happy trying to trick my current amp for the last few years(Marshall class 5) into being a jazzy amp but that's not really what it was designed for. I play a 335 '59 reissue. I really love the versatility of the guitar and look forward to hearing what it sounds like through the GB. There were no GBs in my area but I did try a standard HRD III which I really enjoyed.
Anyway. Great thread with some very helpful information!
thanks
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After having owned a 1996 HRD I which I sold late last year due to developing noise issues (after 20 yrs, maybe a recap due), I also just took delivery of a brand new GB HRD. Sounds wonderful with both my Telecaster and Gibson ES-175.
Bass and treble on 1, mids on 4, reverb on 2 1/2, input 2. Jazz tone just drips out.
Also a great deal through Sweetwater!Last edited by boatheelmusic; 03-26-2017 at 01:26 PM.
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I got the GB amp a few weeks ago. I've been having a lot of fun with it. I'm still trying to tweak the sound. Getting the sweet jazz tones is probably missing due to my playing style more than anything else. But the amp is what I was looking for in tone. I checked the bias and it was at 70. I didn't mess with it since I had read that setting gave the amp a sweeter tone than a lower bias. I was very pleased at how easy it was to check the bias and make adjustments to it. I'm going to try some different 12ax7s. I have a nice stash of nos and new stock tubes I've accumulated over the years. I don't have any 12at7s or 5751s but I'll do some research and try something.
Cheers
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