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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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22nd Jan 2022, 3:31 pm | #1 |
Hexode
Join Date: Feb 2011
Location: Newcastle upon Tyne, Tyne and Wear, UK.
Posts: 280
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Output transformer size
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 |
22nd Jan 2022, 4:41 pm | #2 |
Dekatron
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,088
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Re: Output transformer size
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. |
22nd Jan 2022, 4:41 pm | #3 |
Dekatron
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 4,311
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Re: Output transformer size
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
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23rd Jan 2022, 12:15 am | #4 |
Heptode
Join Date: May 2005
Location: Adelaide, South Australia
Posts: 541
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Re: Output transformer size
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.
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23rd Jan 2022, 12:52 am | #5 |
Banned
Join Date: Jun 2015
Location: Mareeba, North Queensland, Australia
Posts: 2,704
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Re: Output transformer size
The transformers you pictured are a bit piddly really. Look at GJ,s second link. THats what I would recommend.
Joe |
23rd Jan 2022, 4:49 pm | #6 |
Hexode
Join Date: Feb 2011
Location: Newcastle upon Tyne, Tyne and Wear, UK.
Posts: 280
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Re: Output transformer size
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!
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23rd Jan 2022, 6:41 pm | #7 | |
Hexode
Join Date: Feb 2011
Location: Newcastle upon Tyne, Tyne and Wear, UK.
Posts: 280
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Re: Output transformer size
Quote:
I think i will go ahead and test one off the smaller ones for comparison Last edited by pentoad; 23rd Jan 2022 at 6:46 pm. |
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2nd Feb 2022, 7:35 pm | #8 |
Tetrode
Join Date: Jan 2022
Location: Barrio Garay, Almirante G. Brown, Buenos Aires, Argentina
Posts: 76
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Re: Output transformer size
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.
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19th Apr 2022, 1:14 pm | #9 | |
Heptode
Join Date: Oct 2008
Location: Aalborg, Denmark
Posts: 903
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Re: Output transformer size
Quote:
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 |
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19th Apr 2022, 5:46 pm | #10 | |
Heptode
Join Date: Jan 2009
Location: West Lothian, UK.
Posts: 762
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Re: Output transformer size
Their news page https://www.vvttransformers.co.uk/news.htm includes this item:-
Quote:
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20th Apr 2022, 6:08 am | #11 |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
Posts: 7,670
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Re: Output transformer size
VVT are no more but Primary Windings do decent OPT's at reasonable prices.
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20th Apr 2022, 7:15 am | #12 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,195
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Re: Output transformer size
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 |
20th Apr 2022, 11:19 am | #13 |
Octode
Join Date: Dec 2018
Location: Llandeilo, West Wales, UK.
Posts: 1,092
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Re: Output transformer size
Primary Windings do a 5 watt 6V6 / EL84 guitar output transformer (al la Ampmaker kit) which has 4, 8 and 16Ω outputs.
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