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I think I have the mod bug pretty bad.
#11
(05-23-2016, 09:06 AM)GoldenVulture Wrote: Well you won't need a Phase Inverter. :toast:

That's just what I'm looking at right now. You are right. It's not necessary. Only need to worry about 1 more 12ax7.

Everytime I learn something new, it conflicts with something I though I had set to memory. 

If I do that cathode follower setup on V2b like the 2203, I though the PI had to be there to put it back in phase, but I was wrong again. 

I obviously have a few more things to get a better understanding of, but I'm on the right path. I know 10 times now what I knew just a month ago, but there is still more to go. Most all of it is in the power section of these amps.
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#12
PI is only necessary when your running push/pull pairs. splits your signal into a 180 Deg phase difference.
The basic concept of the power amp section is pretty simple. Signal into valve , out of valve and into transformer to speaker.
It is essentially always on max output. Alittle water anology. Water is the signal . Preamp is a tap. Power amp is the pipe its feeding into.

Driving your output valve would be say a 12A** valve. Something like a 12AT7 [ i hope I've got that right ] is used because it has a stronger output current to drive the output valve than a 12AX7. The trade off is it doesn't have as large a gain factor.
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#13
(05-23-2016, 10:42 AM)GoldenVulture Wrote: PI is only necessary when your running push/pull pairs. splits your signal into a 180 Deg phase difference.
The basic concept of the power amp section is pretty simple. Signal into valve , out of valve and into transformer to speaker.
It is essentially always on max output. Alittle water anology. Water is the signal . Preamp is a tap. Power amp is the pipe its feeding into.

Driving your output valve would be say a 12A**  valve.  Something like a 12AT7 [ i hope I've got that right ]  is used because it has a stronger output current to drive the output valve than a 12AX7. The trade off is it doesn't have as large a gain factor.

Yup, I've been doing some much needed reading this morning on power sections. I was thinking the PI worked a little different than it does. Had go back and stare at the 2203 schematic for a minute to see it and make it click, but I see it now.

For some stupid reason I got a little mixed up on how the power tubes ran as well, but we don't need to go into that. I make myself look like a dumbass enough as it is. I guess I just forgot the section on push/pull operation in school.

After what I'm learning this morning and what I want in an amp, I'm going to have to buy a new PT or salvage one from another amp. 

I want a 12-15W version of what my Windsor is now. An exact 2204 setup, on a pair of EL84s. If I can get the transformers sorted out, I can do it. It's not like it has never been done before, and the Classic Tone OT can handle 15W.

Any one have a 1.5A, 120V primary, and 6.3V & 260-290V secondary PT?
I hear Mexico is nice this time of year.
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#14
Only 1.5 Amp PT ? Surprising.
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#15
(05-23-2016, 11:47 AM)GoldenVulture Wrote: Only 1.5 Amp  PT ? Surprising.

I think that's bare minimum.

Edit:

You are right again. The stock PT can handle 880ma. I'm going to more than double that. I need at least 2A.

I need this.

http://www.classictone.net/40-18056.html
I hear Mexico is nice this time of year.
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#16
Let's look at this from another point of view. Not really a start from scratch, but kind of.

I have this.

[Image: 14nk7w.jpg]

It has been nothing but trouble. Every time I fix one stupid little thing, another stupid little thing pops up. And to be quite honest, there is way too much digital shit going inside for me to work on, and it really isn't that great of an amp over all.

GV, please correct me if I'm wrong, but nothing ever says it's a bad thing to have too much transformer. Those 2 pieces of iron take care of 3x12ax7s, and 4x6v6s. Does that mean they can handle 2x EL84s? I'd like to think it would, just looking at requirements.

Those should do what I want quite nicely, huh?
I hear Mexico is nice this time of year.
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#17
A quick rough guess says yes. Find out what the primary winding resistance for the output transformer is, 6V6 based stuff tends to have a higher resistance on the primary of the O.P.T.

Are there any big caps hiding away there ? a Power Supply that can deliver usually has a big can or two.
Is the H.T. from that enough for the EL's ?
Big transformers , big caps = headroom

There looks like plenty of room on that chassis to play around with.
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#18
I'll get back to you on that. I have an amp to tear apart. :evil:

I'm talking EL84s, not 34s. I'm looking at 18W max. If it's powering 4 6v6s, 2 EL84s should be a breeze. I'd hope.
I hear Mexico is nice this time of year.
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#19
EL84
Quote:Maximum Output Power
(single-ended Class A) 5.7W
@10% THD
into 5200 ohms, 250V supply, 4.3VRMS input
.....[O.T. Primary][ supply = H.T. ][ From pre]


Quote:Maximum Output Power

(2 tubes, push-pull Class AB) 17W
@4% THD
into 4+4 k ohms, 300V supply, 10VRMS input
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#20
175ohms across the blue and brown wires.

[Image: 14nrz3.jpg]
I hear Mexico is nice this time of year.
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