Fidelius amp, ultralinear OT, Choke and other things

[uki]

I saw them.

Are the pics good enough to figure out what the power tubes could be ?

Thanks man , It is much clear now what it is all about, I think I got this !!  So then if the desired impedance is 8k then use 8ohm speaker in the 32:1 wiring ? And all those numbers is what the OT can handle yes?

Yes, that's correct, but that also means you wouldn't want to use the other windings and you should just cover them and make a single output jack.  Some minor variances are okay, because the output tubes mirror what the OT is reflecting to them within reason, in your sample case a 16 ohm speaker may work fine in the 25:1 winding because its 10k and that's 'close' to the 8200 you're seeing in the 32:1, but I may be mistaken that it is safe, I don't yet understand what is a tolerable variance there. 

~Phil

Ok so it is good thing to have a switch for the different outputs?

Another thing that bugs me is the tube charts, in some old tube charts for the el34 I see the plate resistance under class B push pull,  few numbers, they are at the line Raa~: 2.4 , 4.0 ,  2.8 , 3.8 (this is what I should look for yes?)
those numbers are from the data sheet page 3: http://tubedata.altanatubes.com.br/sheets/010/e/EL34.pdf
same from this other one: http://tubedata.altanatubes.com.br/sheets/128/e/EL34.pdf   
so those two give about the same numbers.

Now in this other chart there is a totally different number, electro-harmonix one says 15k and it says nominal, what that means ?
Look those two(less info on those new datasheets):
http://multcomercial.com.br/doc/valvulas/eh-el34eh.pdf
http://www.drtube.com/datasheets/el34-jj2003.pdf   

[PRR]

You are getting too tangled-up to unsort tonight.

The PT will give something near 350V with vacuum rectifier, over 450V with Silicon rectifier.

At 200mA, this means 70 Watts or 100 Watts of raw DC.

Tube amp is not much over 50% efficient. The "clean" audio output can be 35W or 50W.

35W-50W is up in the EL34 and 6L6GC class. (Or 6550/KT88 for extra-sturdy.)

The relation of push-pull OT nominal load to DC available (V/A) is near 2:1.

So the vacuum rectifier case wants like 3.5K load, the SI rect case wants 5K load.

At 5K load either the EL34 or the 6L6GC will do fine. The 6L6GC may be marginal at 3.5K and 4K may be a happier load for it.

Sluckey told you what impedances are possible from your OT tests.

[uki]

You are getting too tangled-up to unsort tonight.

Sorry about that. And thanks for the reply !!
Well I'm trying to learn but some things aren't very clear yet in my mind. Sometimes some language barrier may step in the way too, I'm not English born speaker.
And there are lots of things I yet don't really understand, I'll get there eventually.
And that may be why I might not be making the right questions.
I really appreciate everyones help !!!

 

The PT will give something near 350V with vacuum rectifier, over 450V with Silicon rectifier.

At 200mA, this means 70 Watts or 100 Watts of raw DC.

Hmm I'm not sure what the raw DC term means 

Ok I did this little math here:
tube rectifier:  350v * 1.2 = 420  (i know depending on tube type it will change)
silicon rectifier: 350 * 1.4 = 490 

does exist different diodes that can give different ratio lets say 1.3 ?
                         350 * 1.3 = 455 ?


I know this is what is gonna feed the amp B+. (only recently I find why it is called B+(batteries))

Tube amp is not much over 50% efficient. The "clean" audio output can be 35W or 50W.

35W-50W is up in the EL34 and 6L6GC class. (Or 6550/KT88 for extra-sturdy.)

The relation of push-pull OT nominal load to DC available (V/A) is near 2:1.

So the vacuum rectifier case wants like 3.5K load, the SI rect case wants 5K load.

At 5K load either the EL34 or the 6L6GC will do fine. The 6L6GC may be marginal at 3.5K and 4K may be a happier load for it.

What would be a happier load for EL34 ?

Sluckey told you what impedances are possible from your OT tests.

Yes that does help !!
I've just found this doc it may help others to understand transformers. Gotta read it.
  https://nickzouein.files.wordpress.com/2012/03/transformer-calculations.pdf

[shooter]

class B push pull

Most guitar stuff works in AB AB1, so whenever possible pick that on the tube charts.  They also have columns with various plate, and screen(G2) conditions.  so take the values you know, learned, find something close (+/-10%) and "run with it".

[PRR]

> I find why it is called B+(battery)

No.

Early radios used *three* batteries.

Filaments
Plates
Grids

A lot of wires to hook up.

A+/- is filament (perhaps 1.5V at 0.5A)
B+/- is plate (135V at 20mA)
C+/- is grid bias (7.5V at zero mA)

Somehow "B" survived into the wall-power era but A and C names for supplies faded out.

[drgonzonm]

Regarding the choke,
I believe the O/T is wired down stream from the choke, as the plates and and one group of screens are fed from the transformer.

regarding reflected impedance, I would use the values for ultralinear tapping, to determine which tube was originally used. 

If you are not going to use the O/T in U/L applications, then use the AB1 Raa values. 

Regarding tap selection, Please do not put a 4 ohm speaker on you 16 ohm taps, I believe you might fry the O/T. 

Also check out Hammond's 1650 transformer data specs.   modified

[Paul1453]

Regarding the choke,
I believe the O/T is wired down stream from the choke, as the plates and and one group of screens are fed from the transformer.

regarding reflected impedance, I would use the values for ultralinear tapping, to determine which tube was originally used. 

Regarding tap selection, Please put a 4 ohm speaker on you 16 ohm taps, I believe you might fry the O/T. 

Sorry,

OT is upstream from choke, usually.  PT/Rectifier/OT B+/Choke

use the values for ultralinear tapping, to determine which tube was originally used.
How would that tell you what was used?
The KT88 data sheet specifically lists UL applications, others not so much.
You could use/not use the UL taps with most big bottles, no?

There really is no specific ohm tap, but there is a specific Z(Impedance) for each tap.
You can hook up whatever speaker load (4,8,16 ohms) x the taps Z that makes your output tubes happy at the voltage you are running them at, yes?   

[drgonzonm]

All the tubes I listed have been used in U/L applications. 

You are correct, getting info for u/l applications on a lot of tubes is difficult at the best.

Regarding 4 ohm on 16 ohm taps.  The wiring gauge on 8 ohm and 16 ohm taps is typically finer (higher gauge number).  than the 4ohm secondary windings.  While you have higher turns for the 4 ohm windings, with the larger diameter wire, dc resistance is lower. 

Look at the spec sheets for push pull transformers, the ratio of output voltage ratios are 1 for 4 ohm, 1.41 for 8 ohm and 2 for 16 ohm.  PLEASE NOTE I MODIFIED MY PREVIOUS POST.

look at the ohm power calculator, P=V*V/R, leading to the conclusion that a 4 ohm speaker will demand 4 times the power than a 16 ohm speaker.   and twice the power of an 8 ohm speaker.  Hence the warning, do not hook up two ohm or 4 ohm speakers into a 16 ohm speaker jack.

[uki]

> I find why it is called B+(battery)

No.

Early radios used *three* batteries.

Filaments
Plates
Grids

A lot of wires to hook up.

A+/- is filament (perhaps 1.5V at 0.5A)
B+/- is plate (135V at 20mA)
C+/- is grid bias (7.5V at zero mA)

Somehow "B" survived into the wall-power era but A and C names for supplies faded out.

I did fix the post, Thanks!!

Hence the warning, do not hook up two ohm or 4 ohm speakers into a 16 ohm speaker jack.

Yes I'm aware of that, but it is always good to remind those important details, thanks!
Uncle Doug have a video about it, good info ! (speaker part start at 6:52) 1962 Fender 6G12-A Concert Amp Head

Good thing you mentioned the UL taps, I've wondering after reading(file attached) some stuff about UL OT if it would work to use those taps in a Plexi 50?

[shooter]

use those taps in a Plexi 50?

I've always used the UL taps when I have them, although I normally build SE not PP.  They *generally* keep the grid voltage at some ratio below plate voltage, the one's I use are typically 40% tapped.  You may still want to use a dropping R on G2 if you're running close to max on the tubes.

[uki]

use those taps in a Plexi 50?

I've always used the UL taps when I have them, although I normally build SE not PP.  They *generally* keep the grid voltage at some ratio below plate voltage, the one's I use are typically 40% tapped.  You may still want to use a dropping R on G2 if you're running close to max on the tubes.

In the original amp there were a big 1k resistor, maybe 10watts, between the tube and the OT. In the 1st post there is a pic where you can see it.

[sluckey]

If you're gonna build a Plexi just tape up the UL leads. If you're gonna build an old Sunn amp then use the UL leads. IOW, let the schematic you will build dictate when to use UL leads.

[uki]

If you're gonna build a Plexi just tape up the UL leads. If you're gonna build an old Sunn amp then use the UL leads. IOW, let the schematic you will build dictate when to use UL leads.

I see and I will follow you advise, thanks for the heads up. I would like to understand better why not. It is better not to use it due to the way the amp was designed, would it harm the amp or OT or make it sound bad ? 

[uki]

I got cap cans with 32-32/450-500v from the Fidelius amp but the plexi says 50/500, the ones I have aren't close enough to the value or is it possible to use them ?
If not possible to use the 32-32/450-500v ones,  would those small ones handle(really small size DIP 18*25 mm spec 47/500)?
http://pt.aliexpress.com/item/10pcs-lot-500V-47UF-DIP-Aluminum-Electrolytic-Capacitors-47UF-500V-Free-shipping/1860630005.html?spm=2114.02020208.3.36.0Kpq6Y&ws_ab_test=searchweb201556_10,searchweb201602_5_10017_405_404_507,searchweb201603_7&btsid=544a3864-0290-4e4c-bcd7-38f1f811a6eb