Hoffman's 6v6 Plexi build
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Hoffman's 6v6 Plexi build
Hello,
I am ordering parts for a 6v6 plexi build, with 3 preamp tubes. I will use SS rectifier. Do I need sag resistor, if yes, where it will be best to put in. Also, I am planning to use a Hammond 125E OT. Please advise if there is a better option OT wise.
also which secondary lugs should be wired for best output with 8 ohm V30 speaker.
Thanks
I am ordering parts for a 6v6 plexi build, with 3 preamp tubes. I will use SS rectifier. Do I need sag resistor, if yes, where it will be best to put in. Also, I am planning to use a Hammond 125E OT. Please advise if there is a better option OT wise.
also which secondary lugs should be wired for best output with 8 ohm V30 speaker.
Thanks
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- crgfrench
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Re: Hoffman's 6v6 Plexi build
Last edited by crgfrench on Sat 02/13/21 1:42 am, edited 1 time in total.
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Re: Hoffman's 6v6 Plexi build
With a couple of 6V6’s in a push pull config, I’d look for a Classictone Deluxe Reverb OT first. That will give you great output at about 22W. Depending on how you configure the gain stages in your pre-amp this OT will give you the best tone IMO.
I’ve tried Heyboer on two amp builds and Hammond on 1 SE build. I’ve not been able to tell if one has more punch or range than the other. I’ve not tried a CT version of the Hammond yet. It’s on my build list tho. Hammond is definitely the least expensive option.
These are personal opinions and should be taken as such. It’s extremely objective as to the tone you’re looking for. The best answer is to try one and if it just doesn’t have “that” sound, try another.
You’re the creator and the creation is influenced by your ear.
I’ve tried Heyboer on two amp builds and Hammond on 1 SE build. I’ve not been able to tell if one has more punch or range than the other. I’ve not tried a CT version of the Hammond yet. It’s on my build list tho. Hammond is definitely the least expensive option.
These are personal opinions and should be taken as such. It’s extremely objective as to the tone you’re looking for. The best answer is to try one and if it just doesn’t have “that” sound, try another.
You’re the creator and the creation is influenced by your ear.
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Re: Hoffman's 6v6 Plexi build
Specifications for the 125E look good at 8 ohms. You want to use the 8.2K setting (2&5) for a pair of 6V6. I assume frequency response would fall between the 5.6K and 11.6K curves in the Hammond graph below. If so, it's down only about 1dB at the lowest note on a six string (at 15W output). Low frequency THD and phase shift also appear to be well-controlled. Can't comment on the tone personally, but I wouldn't hesitate to use one of these in a build. Bear in mind it won't perform as well at higher output levels.
Jack
Jack
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Re: Hoffman's 6v6 Plexi build
thank you for input. I heard that under sized OT sounds a little pushed/compressed, so lets see how it sounds. and I do not plan to use the amp at full volume.
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Re: Hoffman's 6v6 Plexi build
Is hammond 1760H would give slightly more fuller output than 125E ?
please advise
please advise
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Re: Hoffman's 6v6 Plexi build
1760H is a 20 watt and 125E is a 15 watt. I use a 8 ohm V30 celestion / closed cabinet.
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Re: Hoffman's 6v6 Plexi build
Hello'
I finished the build with 1760 OT. Amp is poweing on okay.
now i want to bias the amp for proper tube life/good tone.
Plz advise me with steps to set the bias
Thank you.
I finished the build with 1760 OT. Amp is poweing on okay.
now i want to bias the amp for proper tube life/good tone.
Plz advise me with steps to set the bias
Thank you.
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Re: Hoffman's 6v6 Plexi build
The first step is to test all your voltages. Then you can put your voltages into a calculator (or do the math yourself). For example: https://robrobinette.com/Tube_Bias_Calculator.htmmehfuzhoss wrote: ↑Sat 03/06/21 2:20 amHello'
I finished the build with 1760 OT. Amp is poweing on okay.
now i want to bias the amp for proper tube life/good tone.
Plz advise me with steps to set the bias
Thank you.
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Re: Hoffman's 6v6 Plexi build
Hello,
I set bias at 22.5ma. sounds decent. B+ is quite high at 462. Amp feels a little stiff and sterile st MV 2/3. with pedals at front sounds amazing and i like it.
any suggestion to make the amp feel a little softer/fatter/spongier!
Any suggestions are welcome.
i have a lite ii that feels spongier than ss 6v6
Thanks
I set bias at 22.5ma. sounds decent. B+ is quite high at 462. Amp feels a little stiff and sterile st MV 2/3. with pedals at front sounds amazing and i like it.
any suggestion to make the amp feel a little softer/fatter/spongier!
Any suggestions are welcome.
i have a lite ii that feels spongier than ss 6v6
Thanks
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Re: Hoffman's 6v6 Plexi build
An EL84 pushed into OD is hard to beat imho
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Re: Hoffman's 6v6 Plexi build
Hello,
I want to lower amp's b+ voltage. I have two 1n5408 diodes and planning to use them in series on filter cap that has 40/20/20/20 uf poles. which pole would be best to solder them into? and how much voltage can I expect to cut down with these diodes? currently, b+ is 462V
advise or recommendation is appreciated.
Thank you.
I want to lower amp's b+ voltage. I have two 1n5408 diodes and planning to use them in series on filter cap that has 40/20/20/20 uf poles. which pole would be best to solder them into? and how much voltage can I expect to cut down with these diodes? currently, b+ is 462V
advise or recommendation is appreciated.
Thank you.
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Re: Hoffman's 6v6 Plexi build
You need Zener diodes. the thread in my signature.mehfuzhoss wrote: ↑Thu 03/11/21 9:18 pmHello,
I want to lower amp's b+ voltage. I have two 1n5408 diodes and planning to use them in series on filter cap that has 40/20/20/20 uf poles. which pole would be best to solder them into? and how much voltage can I expect to cut down with these diodes? currently, b+ is 462V
advise or recommendation is appreciated.
Thank you.
Thanks,
Josh
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Re: Hoffman's 6v6 Plexi build
Those aren't Zener diodes. Each one will drop the voltage about 0.7V in the forward direction.mehfuzhoss wrote: ↑Thu 03/11/21 9:18 pmHello,
I want to lower amp's b+ voltage. I have two 1n5408 diodes
As an aside, I wouldn't recommend installing Zener(s) of any significant value between the reservoir caps and the center tap of the output transformer. Unless your power supply has bleeder resistors, the filter caps will be left with a charge equal to the drop across the Zeners whenever the amp is powered off. That would create a safety hazard for anyone who opens it up.
Jack
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Re: Hoffman's 6v6 Plexi build
That's often true regardless of Zeners. Bleeder resistors are always a good idea there. Of course any experienced amp tech would probably drain the caps before working in an amp...TriodeLuvr wrote: ↑Fri 03/12/21 1:46 amThose aren't Zener diodes. Each one will drop the voltage about 0.7V in the forward direction.
As an aside, I wouldn't recommend installing Zener(s) of any significant value between the reservoir caps and the center tap of the output transformer. Unless your power supply has bleeder resistors, the filter caps will be left with a charge equal to the drop across the Zeners whenever the amp is powered off. That would create a safety hazard for anyone who opens it up.
Jack
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