from 2000
Yes, the amp is from 2000 so is not a point-to-point wire circuit
but have pcb, for now i have only paralleled R6-C6 with a wire
and paralleled C2 with a larger cap so the mods can easily removed
Sure that if i can have the wanted results swapping only one or 2 valves is more simple but for me is a way to learn something about valves and the way they works/sounds (possibly doing a non-destructive interventions!)
Now i'm looking for 2 goods valves to modify the 2 ECC83.
What is the exact function of valve 1 and 2?
Thanks
Yes, the amp is from 2000 so is not a point-to-point wire circuit
but have pcb, for now i have only paralleled R6-C6 with a wire
and paralleled C2 with a larger cap so the mods can easily removed
Sure that if i can have the wanted results swapping only one or 2 valves is more simple but for me is a way to learn something about valves and the way they works/sounds (possibly doing a non-destructive interventions!)
Now i'm looking for 2 goods valves to modify the 2 ECC83.
What is the exact function of valve 1 and 2?
Thanks
V1A is the input preamp, V1B is the post volume control gain recovery, V2 is the phase inverter.
I would leave V2 alone as it isn't going to have that much effect on the clean sound you are looking for. V1A is the most important stage here. It is the stage that gets overdriven first by using humbucking pickups. Humbuckers tend to have much higher output than single coils especially when comparing Gibson guitars to Fender guitars.
This is also why the plate resistor on V1A needs to be changed to a 100K. This will drop the gain of the first stage even if the 12AX7 is left in.
Unfortunately, the first two stages are part of the same tube. What you would really like is to change V1A only to a lower gain stage and keep V1B as the 12AX7. Dropping the gain in V1A will cause the volume control to be turned up higher for the same output level. Having V1B also drop in gain forces the volume control to be turned up even higher to achieve the same output level.
I would leave V2 alone as it isn't going to have that much effect on the clean sound you are looking for. V1A is the most important stage here. It is the stage that gets overdriven first by using humbucking pickups. Humbuckers tend to have much higher output than single coils especially when comparing Gibson guitars to Fender guitars.
This is also why the plate resistor on V1A needs to be changed to a 100K. This will drop the gain of the first stage even if the 12AX7 is left in.
Unfortunately, the first two stages are part of the same tube. What you would really like is to change V1A only to a lower gain stage and keep V1B as the 12AX7. Dropping the gain in V1A will cause the volume control to be turned up higher for the same output level. Having V1B also drop in gain forces the volume control to be turned up even higher to achieve the same output level.
Hi Felipe, at home have only 12AX7 now (a phono preamp) and some electronic components, if i have the valves sure i would try! i'm informing on where can found them but you know now i have few holidays and shop are closed for Christmas so in th meantime i can try to add some resistors/caps in parallel here in there (like advised) and hear what happen, all reversible operations
Love this guitar sound
This is the sound i have in mind :
http://www.youtube.com/watch?v=0MmMn273f54
love expecially that warm and clean chords, nice!
Happy Christmas DIYholics and thank for all!
This is the sound i have in mind :
http://www.youtube.com/watch?v=0MmMn273f54
love expecially that warm and clean chords, nice!
Happy Christmas DIYholics and thank for all!
Wow.
It's a work for a Jazzy amplifier. To go at this way, you can change the input tube for a 12au7, 12ay7 or 12at7. These tubes is very inexpensive and it is good if you can buy someone to test.
I think you can start changing the firts 12ax7 with 12at7 and if you see a lot of gain. You can do the mod to chance R1 into 100k. If you bypass the capacitors of the power supply with a 100nF capacitor. It will be good too.
Can you go to this sound at this video here?
http://www.youtube.com/watch?v=Jx3hd8jHYhU
I think you can have your song with the 12at7 or 12ay7. Modifications can be good too.
Regards,
Felipe Navarro
Merry Xmas for you too.
It's a work for a Jazzy amplifier. To go at this way, you can change the input tube for a 12au7, 12ay7 or 12at7. These tubes is very inexpensive and it is good if you can buy someone to test.
I think you can start changing the firts 12ax7 with 12at7 and if you see a lot of gain. You can do the mod to chance R1 into 100k. If you bypass the capacitors of the power supply with a 100nF capacitor. It will be good too.
Can you go to this sound at this video here?
http://www.youtube.com/watch?v=Jx3hd8jHYhU
I think you can have your song with the 12at7 or 12ay7. Modifications can be good too.
Regards,
Felipe Navarro
Merry Xmas for you too.
In my personal opinion JJ ECC83 and ECC82 are much better than Electro-Harmonix for example, never tried a Sovtek though. I play death metal usually so YMMV. Electro-Harmonix 12AY7 is the only one in current production so there are no options if you don't want to buy NOS 12AY7 (I wouldn't recommend that just in order to do few tests). I haven't tried it myself because I don't want less gain but I've heard it's a good quality tube.
If I recall correctly, an ECC82 doesn't bias to a very good operating point when substituted this way, but because gain is so much lower it might just work well enough. If you like the sound it is good enough but you might still able to get a cleaner sound by drawing the load lines and adjusting the cathode resistor(s) accordingly if you need to. 12AY7 is a direct substitute with slightly lower gain. I don't like the sound of an ECC81/12AT7 at all (JJ ECC83 sounds much better than a Brimar NOS ECC81 to me, in a same circuit).
If I recall correctly, an ECC82 doesn't bias to a very good operating point when substituted this way, but because gain is so much lower it might just work well enough. If you like the sound it is good enough but you might still able to get a cleaner sound by drawing the load lines and adjusting the cathode resistor(s) accordingly if you need to. 12AY7 is a direct substitute with slightly lower gain. I don't like the sound of an ECC81/12AT7 at all (JJ ECC83 sounds much better than a Brimar NOS ECC81 to me, in a same circuit).
mod_evil said:
Yes Felipe, now i have that sound, not very jazzy
moonshine said:
Thanks moonshine for your contribution, another fine example of the sound i love is from Peter Bernstein, he usually use a fender old Vibrolux or a vintage blackface twin or supereverb. He has a slight and mellow distortion when solos and a sweet tone when
play behind the soloist (of course guitar have a strong contribution to his sound)
check this sound :
http://www.youtube.com/watch?v=vmS4kw1FTU4
For that kind of sound ECC82 ought to be a good choice, as it has a gain of ~11 and should not clip at all with a guitar signal, not even when gain is dimed. In an old Finnish valve amp book from '50s they used Ra=47k and Rk=2.2k (bypassed with a 22μF capacitor although 2.2μF should be fine for guitar) for this valve in a Hi-Fi preamp so I would go with those values if you're too lazy (like I am!) to draw a load line and do the calculations.
GA15RV
Hi,
I found this old thread and joined the forum because I have the same amp and similar problems. I try to get a good jazz tone with an ES175 but I find it impossible. I have experimented with all preamp and power tube combinations: 12ax7, 12au7, 12at7, 5571...you name it. I also replaced the speaker with a Celestion Blue (check the jazz sample at celestion's web: http://professional.celestion.com/guitar/features/tone/index.asp). Anyway, the amp is very midrangy, with litlle bass. I am surprised because in most reviews they mention it as a good amp for jazz. As I say, I can't get a good smooth jazz sound out of it. It is VERY clean though, almost impossible to crank it without blowing my ears, so I guess the problem is not headroom but the inherent tone of the amp that is rock voiced. Did you finally improve the tone doing any mods?
Hi,
I found this old thread and joined the forum because I have the same amp and similar problems. I try to get a good jazz tone with an ES175 but I find it impossible. I have experimented with all preamp and power tube combinations: 12ax7, 12au7, 12at7, 5571...you name it. I also replaced the speaker with a Celestion Blue (check the jazz sample at celestion's web: http://professional.celestion.com/guitar/features/tone/index.asp). Anyway, the amp is very midrangy, with litlle bass. I am surprised because in most reviews they mention it as a good amp for jazz. As I say, I can't get a good smooth jazz sound out of it. It is VERY clean though, almost impossible to crank it without blowing my ears, so I guess the problem is not headroom but the inherent tone of the amp that is rock voiced. Did you finally improve the tone doing any mods?
works done!
Hi Lars, have done your mods AND swap the speaker (a celestion vintage 30) with
an used alnico from a Ampeg j20 amp and now the amp have a very nice vintage jazz tone!
Now have a lot of bass, do you think the C3 input cap can be mantained and only put a higher value to reduce the bass a bit?
Thanks
Hi Lars, have done your mods AND swap the speaker (a celestion vintage 30) with
an used alnico from a Ampeg j20 amp and now the amp have a very nice vintage jazz tone!
Now have a lot of bass, do you think the C3 input cap can be mantained and only put a higher value to reduce the bass a bit?
Thanks
Hi revintage, i have done that mods, now the amp have good tone but seems there is always a distortion in the sound, can be due to the too high gain input stage or how can i reduce the distortion?
thanks
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