Twin Regulated Filament Power Supply

[mooreamps]

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[mooreamps]

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[skyboltone]

You don't understand.. I could not find a separate filament transformer for "international" power. Go back my read my design goals.-g

No, I get it. I'm just talking out loud about my own use of both 5 and 6.3V coils so that I can recycle some wonderful old iron I have that doesn't have enough 6.3V to run EL-34s. I like what you're doing.

Dan

[nickt]

Ah... wow... don't usually have that issue in Oz as we're 240V. Thanks for the info - now I see where you're coming from.

Yes, you do. Which is also the reason for the "international" power transformer which, when this amp is built will be shipped, to Sydney.
-g

Chrikey! I'll ownup to being an ex gigging guitarist - I guess my perspective would have been "this room sounds crap!" never thought it was the power tanking out. I guess there's so many things happening with PA's, crews, stages and rooms that you just get used to ignoring what you're hearing unless it's out and out bad and hoping for the best - Thanks g.

[mooreamps]

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[tele_player]

In small clubs like the QuarterNote, I measured the voltage on stage during one of the jam sessions, it was 103 volts.

Yikes, the Quarter Note... I haven't been there since... Wednesday. Small world.

I still can't quite picture how you've wired up the 5V and 6.3V secondaries feeding that circuit, but I like the idea of improving the amp's behavior on severely messed up AC mains.

[mooreamps]

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[paulster]

A regulated DC heater supply for the preamp tubes tough is a good thing. In my amps I'm using 12.6V regulated DC for the heaters, fed into all pin 4's, while all pin 5's are grounded and all pin 9's unused. The result is absolutely hum free amps, even dimed not a tad of a hair of hum

On this photo you may see (and borrow the idea) on the right end of the board, how you might do it. Very close the big blue filter (10,000µF), the additional (black) after the regulator (1,000µF), and the regulator itself (LM317K) mounted to the chassis:
http://www.larry-amplification.de/briti ... pur096.jpg

I use regulated DC for the preamp tubes in all of my builds too, as I think it is a worthwhile improvement over AC heaters.

Rather than use custom-wound transformers as Larry does to get the additional heater winding, I've found that by careful choice of voltage regulator (a low-dropout one is essential) and the use of Schottky diodes for the rectifier (with a very low Vfd) you can get a stable 6.3Vdc from the regular 6.3Vac winding. With the combination I use I can get 6.3Vdc from as low as about 5.5Vac, at which point the power tubes would be suffering and the B+ will be off spec, but it gives the idea.

I've built these onto small PCB cards and use them routinely now on any build I start, or even as retrofits.

[UR12]

You don't understand.. I could not find a separate filament transformer for "international" power. Go back my read my design goals.-g

No, I get it. I'm just talking out loud about my own use of both 5 and 6.3V coils so that I can recycle some wonderful old iron I have that doesn't have enough 6.3V to run EL-34s. I like what you're doing.

Dan

I usually try and ignore Gary’s posts because of his arrogance, but in the interest of helping someone to not blow up a PT, I though I would chime in on this one. One thing I think needs to be said before everyone starts putting your 5 and 6 volt heater windings in series is that you are limited by the lowest current rating on one of the windings. What I mean is that if you have a 2a rating on your 5v winding and a 6.5 amp rating on you 6.3 volt winding and you series the windings, you have limited yourself to the 2 amps on the 5v winding for your total current. If you exceed 2 amps then you could fry your tranny so be careful about just picking up any old tranny and expecting it to do more than it was designed for. Gary isn’t showing us in his schematic just how he has the secondarys wired. Only one labled 6.3, 5 and N with a circle around it. I am assuming that the N is where the two other sides of the windings comes together to make a centertap in which case he really doesn’t have a series configuration. The other thing I don’t understand that instead of trying to kludge something together to work with off the shelf trannys why not just have a tranny wound with the correct 12v heater winding for the application you need it for. There are numerous tranny manufacturers that for just a few dollars more will wind you what you need “If you cant find what you want on a shelf” Seems like a poor design model to me.

It could "easliy" have been the power tanking out. Play though an amp with pre-amp filaments running at 5 volts, you'll see "exactly" what I mean. Also, for the record, any 2 or 3 grand "boutique" amp that does not have twin regulated filaments, not worth the asking price.
-g

There are a lot of amps in that price range that have worked for the last 20 years without the need of DC regulated heaters that were well worth the asking price. Where do you come up with these arrogant BS statements? I would put any of the Trainwreck amps in that category, none have DC heaters, and all are worth 10 times more that their original asking price. I was a gigging musician for 17 years. One thing that any prudent sound guy or musician should do is check the power at a venue before plugging in any equipment. If it is not up to code then don’t plug your stuff in until it is fixed, plain and simple.

[brownnote]

Also, for the record, any 2 or 3 grand "boutique" amp that does not have twin regulated filaments, not worth the asking price.


-g

My first criteria is that the amp sounds good.
If the amp sounds like dogshit, I don't care what the price is, or what design features it has.

[mooreamps]

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[mooreamps]

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[UR12]

It's a great design model. Just not willing to give away my research to my compeition. Folks who would rather pinch my design work of the web, instead of being straight and up front with me. -sorry.....

-g

I would think a GREAT design would incorporate the right tranny and not one that has to be retrofitted with a dual bridge twin regulated DC heater supply to make it work.

NOT TRUE !!!! A double-bridge circuit takes the 6.3 volt winding at full rated current value and the 5 volt winding at full rated current value......

-g

You need to finish your sentence. What I said was true. If you have a 5 volt winding that is rated at 2 amps and if you try and pull more than two amps either at 6.3v or at 5v you are exceeding the rating of the tranny. In your paranoia to exclude how you have the trannys wired, it would appear that you have people on this forum believing that if they just series the 6.3 and 5v windings to get 11.3 and then rectify that they can somehow come up with the additonal curent to drive a set of power tubes heaters. While it MAY be true it might also be false depending on how much current is needed. Personally , for reasons already discussed by others in this thread I can't see the need to use this type of circuit to regulate the heaters in a PP amp. You were discussing a SE design with 2 different power tube types and you will probably need all the regulation you can get in that case.

Why even come here and start a discussion like this if you are paranoid that someone is going to steal your design. If you really feel that way spare the rest of us the condescending attitude and keep it to yourself.

[skyboltone]

I usually try and ignore Gary’s posts because of his arrogance, but in the interest of helping someone to not blow up a PT, I though I would chime in on this one. One thing I think needs to be said before everyone starts putting your 5 and 6 volt heater windings in series is that you are limited by the lowest current rating on one of the windings. What I mean is that if you have a 2a rating on your 5v winding and a 6.5 amp rating on you 6.3 volt winding and you series the windings, you have limited yourself to the 2 amps on the 5v winding for your total current. If you exceed 2 amps then you could fry your tranny so be careful about just picking up any old tranny and expecting it to do more than it was designed for

Ah come on Dana. You mean you don't believe in the "Free Lunch"?

This is what I come out of this discussion with: Also, if you don't mind me interjecting a completely OT statement......in buck boost situations the lower amperage winding only contributes current in proportion to the IXE that it contributes to the circuit. Yes, I know, this is NOT one of those cases! Anyway, does this work? With one volt lost in the rectifier you get 10.3 into the filter. Using 1.35 times Vin to a Cap entrance filter, that leaves us with 13.9VDC minus 1.9 Vref for the regulator gives us maybe 12 VDC for the preamp filaments. ?

OH! Figure .45A for the pre filaments and 3A for the PA filaments.
[IMG:718:497]http://i21.tinypic.com/1q25jq.jpg[/img] Well, for reasons I cannot explain, tinypic refuses to connect the lines. I've edited and re sent the file twice to no avail. Continue lines as needed.

[UR12]

Ah come on Dana. You mean you don't believe in the "Free Lunch"?

This is what I come out of this discussion with: (Damn, paint sabotaged me........continue lines as needed )Also, if you don't mind me interjecting a completely OT statement......in buck boost situations the lower amperage winding only contributes current in proportion to the IXE that it contributes to the circuit. Yes, I know, this is NOT one of those cases! Anyway, does this work? With one volt lost in the rectifier you get 10.3 into the filter. Using 1.35 times Vin to a Cap entrance filter, that leaves us with 13.9VDC minus 1.9 Vref for the regulator gives us maybe 12 VDC for the preamp filaments. ?
[IMG:718:497]http://i23.tinypic.com/dfy5go.jpg[/img] OH! Figure .45A for the pre filaments and 3A for the PA filaments.

No I don't, and I don't think Mr Kirchoff did either Yes your circuit should work as described but since the curent flow is through the windings in series I don't care what you regulate the voltage down to if you try and hook a load to this thing that will require more than 2 amps from the 5 volt winding you run the chance of melting down your tranny. That's all I'm trying to say.