output tranformer size and wattage like bandmaster Vs Super

[steveo7868]

I have always been curious how a lot of older 6l6 amplifers have a reasonably sized output transformers
and I have also used and abused the classictone 40W bandmaster transformers on closer to 50W amps
like a JTM-45 type, even the power level of the bandmaster itself as opposed to a super , just seems
the transformer size is way bigger, I know a lot of guys go for the overbuilt approach, and I get that too...
just curious about how folks here think about that , like is there any mojo in a slightly undersized OPT?

[sluckey]

...like is there any mojo in a slightly undersized OPT?

Absolutely! Just look at some of those Valcos, Silvertones, Supros, etc. that people are drooling over these days.   

[shooter]

 


In my xSE world, I like big UL iron, closer to HFi than saggy saturated.
I did go "up" in my Slivertone build...a little 

[AmberB]

If you're building a tube bass amp, sag is not what you want, but for guitar, a lot of people like that sag because it can add something to the distortion characteristics that they're looking for.  That's probably why some people also prefer a tube rectifier...

[Ed_Chambley]

Of all the "clone" amps I have built, the Brownface 63 Vibroverb has been built the most.  Side by side with CTS 10"s with my Blackface Deluxe 1, 12" Greenback, the 5881's breakup sooner and more gradual in the 6g16 Circuit.  The correct output transformer is small.  Compared to the 6G6B Bassman, the output transformer appears half the size, but the same size vibrolux.  Anyway, larger iron makes a larger sound, cleaner, louder sound with more punch, you then have to figure out to distort you new cleaner signal earlier.

[shooter]

search the forum for "how to increase headroom"
It seem alot of builders "want that".  there are lots of "fixes", including bigger OT iron.
distortion is pretty each these days, having both clean AND distorted requires some homework

[dude]

If you're a pedal guy, maybe the big iron is what you want, more headroom for the pedal to break-up
I don't use pedals, maybe a compressor and an OD pedal, maybe. The 6V6 Plexi's I have sound pretty good with an 18 watt OT, the 6V6's saturate that OT.  I use 5881's in one Plexi but did upgrade the OT to 30 watts, sounds great, actually it's my best sounding 6V6 or I guess 5881 plexi I have.

[shooter]

The 6V6 Plexi's 

when I build my version, I didn't have 6V6, so I used EL34's, self biased, I also used a UL- OT meant for a Marshall 100W (It didn't saturate:)
according to the guitarist's that worked with me during tweaking; "That's the best amp you ever created", It's also the only one that produced a  positive ROI 

[pdf64]

My understanding is that with smaller OTs we may push them past the linear section of the BH curve, up into the rounded off knee area. I think that will do the stuff typically described as OT saturation.
Actual hard saturation would sound like ass, as inductance would collapse, the OT's primary impedance would = its resistance, and power output would fall through the floor.
But that can't happen with pentode output stages anyway, due to their high output impedance; not like triodes or especially BJTs, that can push more current as load impedance falls.
Rather our output stages can only ever be pushed up to the knee of the curve, can't go past that and flatline into saturation.
Whatever, it's only a low freq thing; as freq rises, the amount of magnetic material in the core required to maintain the magnetic field reduces. That's why SMPS are so small compared to regular linear supplies, they're work at a much higher freq so as to reduce the transformer size needed.

[Ed_Chambley]

The 6V6 Plexi's 

when I build my version, I didn't have 6V6, so I used EL34's, self biased, I also used a UL- OT meant for a Marshall 100W (It didn't saturate:)
according to the guitarist's that worked with me during tweaking; "That's the best amp you ever created", It's also the only one that produced a  positive ROI 

Can you really listen to a Guitar Player?  Come on now!


I built a Matchless Chieftan, K bias EL34's.  Used a PT 275-0-275, so plate volts are lower and used a 6.6K multitap.  Of course, not much difference in the LTPI voltage.  It reminds me a lot of the Trainwreck Express.  Is it loud coming out of a 4, 12 with Greenbacks?


My point being is I find MOST amps sound great when you turn them up till breakup, good breakup.  Roll back on the guitar to get clean.  Then usually the additional signal created from rolling up will let me get snappy and making them squeal a little.  Boost that and Singing Tube Nirvana.


The OT saturation and tone stack from the brown era Fender amps is popular at present.  I find even with the 6G6B Bassman you have a bit of hair on the notes.  Just a little.  Can you cover Van Halen well?  No, but Mark Knoffler, yes.


Money for nothing, Chics for free!

[steveo7868]

Interesting discussion, thanks guys