Hello,
Can anyone tell me how to run a single ended 6v6 in triode mode?
I would like to perform this modification on this circuit: http://www.kbapps.com/audio/schematics/tubeamps/fender/champ5f1.html
I built this amp and it sounds great, but now I want to see what else I can do with it.
Thanks so much!
Can anyone tell me how to run a single ended 6v6 in triode mode?
I would like to perform this modification on this circuit: http://www.kbapps.com/audio/schematics/tubeamps/fender/champ5f1.html
I built this amp and it sounds great, but now I want to see what else I can do with it.
Thanks so much!
WRyan said:
I would say fugeddaboudit. It's a guitar amp, not HiFi. I'd leave it alone if you like the sound. The specific "tone" of guitar amps is heavily dependent on its particular distortion. As such, trying to change it, especially by trying a more linear final, just might end up sounding too dull.
Furthermore, 6V6's don't do so well trioded as SE amps. The output power is quite low. You can go here: Frank's and check out some 6V6 specs. These include trioded plate characteristics. Run some loadlines and you'll see what I mean.
oldeurope said:
At 300V/40 mA 5K load you get approx. 1.6W with 5% THD.
The 45 is not exceptionally efficient as well (because it has low Gm essentially) but it is much better than 6V6:the sonic perfomance is in another league, at low levels THD is much lower and the IMD is incomparably better, especially with filament DC supply.
So the 6V6 gives an anode efficiency of 1.6/12 = 13.3%!!
The 45 needs 250V/34 mA only for 1.6W at the same THD and so its efficiency is 18.8%.
The triode connected EL84 is much better than 6V6 as you get approx. 2W with less than 8W anode dissipation.
Cheers,
45
Re: Re: Running Single Ended 6V6 in Triode Mode
I disagree almost completely. First off, the low power output allows the amp to be overdriven without it reaching ear-splitting volume levels.
Second, the reduced gain/changed gain structure will change the tone of the amp. Whether he likes the tone or not only he can decide. As well, the reduced gain will also reduce the amount of NFB, also changing the tone.
It's likely the amp will be "cleaner" in triode, and depending on playing style, etc., it can be very pleasing. I've installed "triode switches" on a number of Fenders, and the owners have been pleased in every case.
I agree with revintage - I'd put a switch in so I could have it either way, triode or pentode.
Miles Prower said:
I disagree almost completely. First off, the low power output allows the amp to be overdriven without it reaching ear-splitting volume levels.
Second, the reduced gain/changed gain structure will change the tone of the amp. Whether he likes the tone or not only he can decide. As well, the reduced gain will also reduce the amount of NFB, also changing the tone.
It's likely the amp will be "cleaner" in triode, and depending on playing style, etc., it can be very pleasing. I've installed "triode switches" on a number of Fenders, and the owners have been pleased in every case.
I agree with revintage - I'd put a switch in so I could have it either way, triode or pentode.
Re: @ #7
What do you mean?
I could not find in practice a better option for a good performance.
Basically you have to "squeeze" the tube.
You can go for lower dissipation but power output will decrease accordingly and above all it will sound worse.
However, a 6V6 can be used at very low anode voltage (24V for both anode and screen grid, 1.5V bias) with 10K load giving 20mW output....
Cheers,
45
oldeurope said:
What do you mean?
I could not find in practice a better option for a good performance.
Basically you have to "squeeze" the tube.
You can go for lower dissipation but power output will decrease accordingly and above all it will sound worse.
However, a 6V6 can be used at very low anode voltage (24V for both anode and screen grid, 1.5V bias) with 10K load giving 20mW output....
Cheers,
45
Thanks to everyone for your time and comments. A few points of clarification:
This amp is really a learning project. I want to hear for myself how these kinds of changes sound and feel. This is the second of many “experiments” to come…. already removed NFB and I like the change, but can see use in both. I plan to add a switch for that.
In the guitar community, it is pretty commonly accepted that there is a useful difference between pentode and triode mode. Many seem to feel that triode mode is noticeably “smoother” and maybe a bit more compressed. If I find this to be true, it will be a useful feature.
One other appealing thing (to me) is the lowered output level. Home recording can’t always tolerate a cranked 30 – 50 watt tube amp. My situation will benefit from a lowered output level.
Doubtful that a SE 6V6 in triode mode is really going to do me much good on stage though…time to start my AC30 project!
Revintage provided the info I was looking for… with a schematic! Thanks revintage!! … and thanks to everyone for your comments. I am learning a lot by reading them!
This amp is really a learning project. I want to hear for myself how these kinds of changes sound and feel. This is the second of many “experiments” to come…. already removed NFB and I like the change, but can see use in both. I plan to add a switch for that.
In the guitar community, it is pretty commonly accepted that there is a useful difference between pentode and triode mode. Many seem to feel that triode mode is noticeably “smoother” and maybe a bit more compressed. If I find this to be true, it will be a useful feature.
One other appealing thing (to me) is the lowered output level. Home recording can’t always tolerate a cranked 30 – 50 watt tube amp. My situation will benefit from a lowered output level.
Doubtful that a SE 6V6 in triode mode is really going to do me much good on stage though…time to start my AC30 project!
Revintage provided the info I was looking for… with a schematic! Thanks revintage!! … and thanks to everyone for your comments. I am learning a lot by reading them!
Re: Re: Re: @ #7
680 ohm for 70 mA at 165V ? That looks impossible to me.
Anyway, in my situation, going for lower supply voltage resulted in a too "dark" sound (good only if you overdrive the tube but not in the clean mode).
By squeeze I mean running it at high plate dissipation (basically no less than 8W).
45
oldeurope said:
Are you ready for a change? Yes we can.
I think you'll take 70mA @165VDC, don't you?
A 680 Ohms cathode bias resistor will help.
Kind regards,
Darius
PS: What does "squeeze a tube" mean?
680 ohm for 70 mA at 165V ? That looks impossible to me.
Anyway, in my situation, going for lower supply voltage resulted in a too "dark" sound (good only if you overdrive the tube but not in the clean mode).
By squeeze I mean running it at high plate dissipation (basically no less than 8W).
45
Yes, I get a blazing 1.5 watts out of my 6V6 simple SE, but it sounds really really good. Not quite as good as the Tubelab SE with 45's but the whole amp cost me less than one of the OPT's did on the 45 amp. These are HiFi amps though. I think that if you want a clean low powered sound for a guitar a trioded 6V6 may work, but I prefer the sound of a 6V6 in pentode cranked to 11 for guitar.
Re: @ #14
I think you should play a guitar before passing judgment!
Also, everyone likes a certain guitar/amp combination depending on his taste and the genre of music he plays.
For me, triode connection works only together with crunch and distortion, while pentode connection is more flexible.
45
oldeurope said:
I see you didn't understand the wink. (see #13)
Squeeze a triode: This is the word I was searching for describing how people run triodes these days. Thanks
Kind regards,
Darius
I think you should play a guitar before passing judgment!
Also, everyone likes a certain guitar/amp combination depending on his taste and the genre of music he plays.
For me, triode connection works only together with crunch and distortion, while pentode connection is more flexible.
45
On my 5F1 build I also disconnect the NFB for a little "more." Also added a bypass cap to the 1st stage. I used a 0.1u to favor the higher frequencies since mine was a little dark. Try a 25u there if you want to keep the bass/treble balance as is, but want even more "gain" (in the guitar amp sense.)
Here's a clip at various guitar volume settings:
http://www.geocities.com/jjsant/champo_sm58.mp3
Here's a clip at various guitar volume settings:
http://www.geocities.com/jjsant/champo_sm58.mp3
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