Output transformer size

[pentoad]

Is this size of OPT too small for a 6V6 champ style guitar amplifier about 6 watt
they are most likely from a radio such as dac90a or similar

[kalee20]

It depends what sort of performance you're expecting!

They'll work, and should be fine for a practice amplifier. But if it's a bass guitar and you want all of your 6 watts at low distortion, then you might be disappointed.

[GrimJosef]

You could check out a couple of commercial 5-6W 6V6 transformers, such as these

https://www.hammfg.com/files/parts/pdf/1750C.pdf
https://www.vvttransformers.co.uk/vts13141-1100.htm

to get an idea of the size of units specified for this job.

Cheers,

GJ

[retailer]

I had an original mid 60's Champ and the OT I recall looked quite puny and no different from the type you'd see in a mantle radio that ran a 6V6 in the output, those you have pictured look ok size wise - just make sure the impedance is correct. The attached pic is of a mid 60's Champ OT you can judge the size compared to the octal sockets.

[joebog1]

The transformers you pictured are a bit piddly really. Look at GJ,s second link. THats what I would recommend.

Joe

[pentoad]

It doesn't matter if it small, so long as it can take the power. If it saturates it produces a better rock guitar tone - allegedly!

[pentoad]

Originally Posted by retailer

I had an original mid 60's Champ and the OT I recall looked quite puny and no different from the type you'd see in a mantle radio that ran a 6V6 in the output, those you have pictured look ok size wise - just make sure the impedance is correct. The attached pic is of a mid 60's Champ OT you can judge the size compared to the octal sockets.

It does look the same size - I have tested a bigger one below ( but it might be overkill ) in theory it should sound better
I think i will go ahead and test one off the smaller ones for comparison

[Osvaldo LW1DSE]

The size of a traffo depends mainly in the power capability and the frequency range. An old professor known as Ladislao Koros from the Universidad Nacional de La Plata (a city here in Argentina) wrote a paper in 1950 where he explain that a large core size warrants high frequency range because larger area means small number of turns, so small interwinding capacitance and smaller leakage inductance, although at first view it seems contradictory.

[tri-comp]

Originally Posted by GrimJosef

You could check out a couple of commercial 5-6W 6V6 transformers, such as these

https://www.vvttransformers.co.uk/vts13141-1100.htm

Cheers,

GJ

Is VVT still in business ?
In the past I've ordered several transformers from them and never been disappointed.
Some time ago, maybe in connexion with the Brexit, they stopped selling outside the UK and last fall I believe they announced closing all together by the end of 2021.
Their web-page is still up but the price calculatier seems to have be taken off-line, or that could be possibly only for foreign customers ?
Anybody knows what's going on ?

rgds,

/Torben

[buggies]

Their news page https://www.vvttransformers.co.uk/news.htm includes this item:-

We will be offering surplus materials for sale shortly after a stock take.
We will retain some equiment and materials for personal use after formal close down at the end of our financial year on 31 Mar 2022.

[Diabolical Artificer]

VVT are no more but Primary Windings do decent OPT's at reasonable prices.

[Ed_Dinning]

There is also the tradeoff that a small transformer may well have very fine primary windings that will not like the current and effect the power output as they heat up and increase in resistance.
If overdone they will eventually burn out

If it gets hot then it is too small; also note that copper has quite a high coefficient of resistance and there is a very measurable difference in resistance between 20C and 50C

Ed

[snowman_al]

Primary Windings do a 5 watt 6V6 / EL84 guitar output transformer (al la Ampmaker kit) which has 4, 8 and 16Ω outputs.