Choosing a vintage recicled PT for 5f11 project!

[Chuck H]

Hey Chuck, isn't that Depth control for varying the bias voltage as a function of a bias modulated tremolo? See the top half of the first 12AX7? Doesn't that function as the tremolo oscillator and the depth is the adjustment for the effect it has on bias voltage? That .25uF 400 volt cap couples the tremolo output signal to the 250k pot and it functions as a voltage divider for the -31 volt non-adjustable bias and the adjustment for tremolo depth. You can see the speed control just above it. It is a Vibrolux after all. Not a huge deal, just to clarify is all. Were it not a tremolo amp, it would indeed vary the bias voltage.

What did you think I was talking about? I don't understand your direction or reason for correction.

[DRH1958]

This is copy and pasted from your response: "That tap is just a convenient way to derive bias voltage. You can design a bias circuit without the tap and in fact that's what the GA30rvt does..." It sounds from this that you were just describing it as only a bias adjustment since the OP asked the question " what about the tap on the HT winding that goes to the "depth" pot?". If I interpreted your answer wrong, then I apologize. I guess having read many of your very detailed responses in the past, that you would have gone into more detail as to how these two interact with each other through that 250k pot to adjust the interaction of the fixed bias supply and bias modulation from the tremolo. Again, I apologize it I took it wrong. I was just trying to clarify it for angelothewolf. At the end I did say this: "Not a huge deal, just to clarify is all".

EDIT: This stems from me liking things to be very clear. Everyone has been so helpful to me here and explained things very well, so I like to do the same since we don't know the ability level of people who pose questions. So for me, I like to err on the side of more info to be sure people understand things clearly.

[Chuck H]

Well you DID take it wrong

I was operating on the assumption that AOTW (angelothewolf) just needed to know that the circuit could be duplicated without that tap. I was remiss in not explaining the circuit, which, your right, I usually do. Somehow I interpreted that it was sort of "too much information" at that moment. But any questions that arise from explanations are also good questions

[angelothewolf]

I bought an old Peavey Classic 30. With a fried PT. The original idea was to restore it and keep it for myself. Then I take it apart, and when i saw that awfull PCB (in wich i have worked many times before) I thought maybe is a much better idea to build one from scratch inside of it. So as it seems quite a tweed, I choose the 5F11...

I have a pair of hammond 7591 and was thinking to use that too, with the Gibson output iron... So I think this is going to be a Frankestain, I really like to keep it simple, with good parts. Ill try to draw the circuit, maybe with the bias arrangement of that later version of the Vibrolux, all your thoughts are very welcome!

[Chuck H]

That sounds like a good plan. Thanks DRH for directing us to an appropriate schematic

[J M Fahey]

I bought an old Peavey Classic 30. With a fried PT. The original idea was to restore it and keep it for myself. Then I take it apart, and when i saw that awfull PCB (in wich i have worked many times before) I thought maybe is a much better idea to build one from scratch inside of it. So as it seems quite a tweed, I choose the 5F11...

Many modern awful PCB amps can be improved by stripping them bare and mounting an eyeletted or simiar board inside.

NOT because "PTP is better than PCB" which is nonsense but because the older simpler circuits are MUCH better than modern *designs* , mainly because these try to squeeze too much from a couple tubes.

Compare a JCM900 which boasts of 2 switchable channels, high gain, active effects loop, reverb, compensated line out and a couple other gimmicks (triode/pentode, etc.) to a muscular Plexi, both have 3 x 12AX7 and same complement of power tubes, the old one has only 1 channel , no master, no loop or reverb, but provides bone crushing killer sound.

Same with converting the "Classic"º 30 to a Tweed.

Only problem is that you end up with too many empty holes on the front panel

[Justin Thomas]

Only problem is that you end up with too many empty holes on the front panel

Meh, sheet aluminum is cheap AND easy to work! My solution to that problem, anyway...

Or you could just stick in random pots, lights, & switches, label them with what they actually DO in the circuit, and listen to the customer rave about the subtle nuances that the "Nothing" switch provides in the On position...

Justin

[Leo_Gnardo]

Same with converting the "Classic"º 30 to a Tweed.

Only problem is that you end up with too many empty holes on the front panel

Too many holes? Let the amp ventilate! Put in lights. Dummy knobs in kandy kolors?

With Peavey Classic series amps, you also have those series wired filaments to contend with. phooey.

[angelothewolf]

Hi there, so, im planning to use the gibson OT and 7591 instead the 6V6s. 5E11 circuit except for the bias negative supply wich will be from the 6G11-A circuit
AAny suggestions about the 7591s? just pinout or I will have to do another correction? what you think?

[angelothewolf]

[angelothewolf]

Hi there, just to update. Now I have all the pieces to mount this amp. Im using that gibson transformer wich has a 720VAC HT secondary, so Im thinking how to deal with it. I know that I can drop that voltage after rectification for the 6V6s, but do you think this will be too much voltage for the rectifier tube?

[Chuck H]

I didn't reskim the whole thread so I don't recall if you referenced a CT. If you have one then it's easier to reference 360-0-360. That would be a lot for a 6V6, typically. A 5y3 rectifier should handle the voltage with no trouble and will drop a lot of voltage. You'll probably end up with around 410V-420V. No problem for 7591's or most modern 6v6's. I wouldn't recommend running used good pulls of any vintage 6V6. Otherwise I think you're ok.