Tino Z's 5b6 ptp

[RWood]

Can anyone venture a guess as to the effects of using 47/22/22 filters instead of 30/20/20 in such a finicky build as octal 5b6.
I have a drawer full of 47s and 22s

A lot of posts I've read say 5b6s are kind of hit or miss, but tino's ptp is usually a great.

[Phil_S]

I can't find a maximum microfarad rating for the 5U4 or 5U4GB for the first filter cap. The Tung Sol data sheet for 5U4GB indicates 40mf for typical operation. In the bad old days of 5B6 manufacture, caps where probably spec'd -20%/+50%, meaning that 30mf cap could have been 45mf and passed as OK by the factory.

There is no practical difference between 20mf and 22mf. It's my impression that 20mf, 22mf, and 25mf are regularly interchanged and that people use whatever they have available. Think of that swap as no change at all.

The general effect of more filtering (47 vs 30) is to stiffen the power supply (less sag). Given how stout the 5U4GB is to begin with, I'm guessing you won't hear much difference.

I'd use those if that's what I had on hand.

As an alternative, you might consider a pair of 22mf in parallel for 44mf to get you a little closer to 30mf, but really, the difference between 44mf and 47mf is insignificant. In practice, because tolerance specs allow it, your 44mf pair might actually have more capacitance than the single 47mf or maybe not.

You could also go with a single 22mf for the first filter cap. If you don't like what you hear, you can always change it.

IMO, using 47mf or 22mf instead of 30mf isn't that much of a change, especially on the 5B6, which has a relatively light current draw for that particular rectifier tube.

[Structo]

Also figure that most electrolytics have a tolerance of 20% +-

You have to step it up quite a bit before you notice it.

[M Fowler]

I used a can cap 40/20/20/20 on my Tino PTP 5b6 cage amp and it works very well running 5u4, 5AR4 and SS plug. Currently owner is using SS plug for more B+.

We have run 6L6, 6550, KT88 and KT120 in the amp to see which was preferred. I think he is currently running NOS 6L6GC, NOS 6SC7 and NOS 6SL7.

The design is very good even without a choke which I have often thought about adding not that it is needed I just always wondered about it.

Building another cage amp 5b6 identical to my first one but will be using axial filter caps on this one 47uf, 22uf, and 22uf.

Also purchased two more of those retro toasters for 5b6 preamps.

Mark

[RWood]

Thanks guys. I know the "electro/math" as my mentor called it. I was just wondering if anybody used higher values on this particular circuit which has a reputation (justified or not) of being finicky.
I've played through three, two of which were combos which were a bit flabby and microphonic with a touch too much sag. The third was a PTP head which I placed beside a 15" cabinet...It gave my semihollow bass the sweetest tone I've ever heard. He let me swap the rectifier with a Copper cap which tightened the sag ever so slightly...Instant mojo !!!!
He had followed Tino's book so I got one.

This will be my 5th build (2nd PTP). I'm following Tino's layout with the exception of the caps which I stacked in a pyramid and soldered to terminal strips, and a standup Weber PT that I already have, so no cutout for that.
I don't know if orientation/proximity of trannys matter yet.

I'm a big fan of the cage head M Fowler did.

[JazzGuitarGimp]

OR, you could use THREE of those 22's: two in series for 11, then parallel that with the third for 33! Weeeee….

[Structo]

Welcome to the Amp Garage RWood.

You will find similarly afflicted tube heads here.

The only advice I can give is to try it and see if you like it.

[RWood]

Anyone tapped a line out on this amp?
Best place and configuration would be appreciated.

[M Fowler]

Anyone tapped a line out on this amp?
Best place and configuration would be appreciated.

Yes both a passive effects loop and direct out off speaker jack.

You can see a 8ohm 25w resistor on right side I tried to have it so you could run the amp without speaker load.

But it didn't work, not sure if the 8R/25w (line out jack) has to be isolated from ground to get that speakerless function to work.

Any who the effects loop and direct out work great just keep an impedance load on the amp.

Mark

[RWood]

Thanks M Fowler... I don't intend using without speaker as the amp will be my monitor. The line out off the speaker jack is not a good idea either because I don't want to change audience level if I need more or less stage level. I could just mike it but a line out would be easier since we only do one gig every other month that requires using the board. Mostly venues small enough for just 30w amp.

The last mod I did on a ss amp had a line out tapped off the end of the preamp board before the power section board to a pot for level control. I've never done it on a tube amp before. I know I'll lose the power tube tone but that'll be ok. I was just wondering which point I should tap from with PTP.

[M Fowler]

See the attached 5b6 schematic.

[RWood]

As I see it, that is an effects send/return...right?
So if I tap the input side of the vol pot I'd get a constant signal for line out independent of amp volume, and tapping the wiper, the line out would be variable, dependent on volume pot... or am I missing some theory?

[M Fowler]

I think you should be fine sending the preamp signal from pin 2 through a .01uf/600v cap to the preamp out jack hot terminal.

The rest of the circuit would remain stock no effects loop.

[tubeswell]

If somebody can post a pic/gutshot of Tino's layout with the reservoir cap clearly shown, we could tell what he used.

[M Fowler]

Tino used a 3 section can cap 30/20/20 @450v