What’s the minimum power transformer required to build a gainclone amplifier?

Katapum · 27th November 2005, 02:51 PM

Hi all,

I have two power transformers with 2 separated winding each (2x12V/3.33A +2x12V/3.33A). Is it enough to build an inverted gainclone (Thorsten style)?

Any comments or suggestions are very welcome.

Katapum

neutron7 · 27th November 2005, 08:17 PM

if you can get 2x24v 3.3a each thats about 160 VA which should be enough for stereo pair. or use one each side if you prefer . then you will have power to spare.

Katapum · 27th November 2005, 10:18 PM

Hi,

Just to clarify I have two power transformers:

One (two separated windings and no centred tap):
12Vac/3.3A
12Vac/3.3A

Another (two separated windings and no centred tap):
12Vac/3.3A
12Vac/3.3A

I don´t have any 24Vac transformer.

(att. IGC schematic)

Katapum

peranders · 27th November 2005, 11:05 PM

They might do if your average output power is far from 100%. If the transformers are getting real hot they are probably too small for your needs.

If I understand you right you have two transformers of 80 VA each. This will do. I'm quite convinced of it.

tja · 27th November 2005, 11:28 PM

Quote:

Originally posted by Katapum
Hi,

Just to clarify I have two power transformers:

One (two separated windings and no centred tap):
12Vac/3.3A
12Vac/3.3A

Another (two separated windings and no centred tap):
12Vac/3.3A
12Vac/3.3A

I don´t have any 24Vac transformer.

Put the secondaries of each transformer in series, that will give you two transformers with 24V. One for + and one for -.

Take

Leolabs · 28th November 2005, 02:43 AM

AC12V from a transfomer still sufficient to power a gainclone,only the output power get reduced.

neutron7 · 28th November 2005, 06:37 AM

if you do as Tja said

you can use the transformers together to be equivelant to a 160 VA 24 + 24 which will work very well.

you have to connect the 2 winding of each transformer in series, so you will need to make sure you know the phase.

Katapum · 28th November 2005, 10:49 AM

Hi all,

I built the amplifier. It’s incredible bad. I need to turn the pot at 3 o’clock to get some power (but not too much). Maybe I have done something wrong. The amplifier worked with 95dB diy open baffle speakers.

I have also a 300B tube amplifier (9W) and it has much more power.

What do you think?

Amplifier also has a little hum problem but I think it’s because the power input is too near input line and output speakers. Am I right?

Quote:

so you will need to make sure you know the phase.

How can find winding transformer phase (I have only a DMM)?

Katapum

tja · 28th November 2005, 10:54 AM

How did you wire the transformers?

Take

Katapum · 28th November 2005, 11:00 AM

Hi,

Katapum

27th November 2005, 02:51 PM	#1
Katapum diyAudio Member Join Date: Mar 2003 Location: Europe	What’s the minimum power transformer required to build a gainclone amplifier? Hi all, I have two power transformers with 2 separated winding each (2x12V/3.33A +2x12V/3.33A). Is it enough to build an inverted gainclone (Thorsten style)? Any comments or suggestions are very welcome. Katapum

27th November 2005, 11:05 PM	#4
peranders Electrons are yellow diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 1	They might do if your average output power is far from 100%. If the transformers are getting real hot they are probably too small for your needs. If I understand you right you have two transformers of 80 VA each. This will do. I'm quite convinced of it. __________________ /Per-Anders (my first name) or P-A as my friends call me BPA300 Group Buy Round 4, SMD-kit and DRV134 pcb, checking interest Sign up HERE Rectifier bridge RFB03 Group Buy Round 2, checking interest Sign up HERE

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27th November 2005, 08:17 PM	#2
neutron7 diyAudio Member Join Date: Dec 2003 Location: Toronto Canada	if you can get 2x24v 3.3a each thats about 160 VA which should be enough for stereo pair. or use one each side if you prefer . then you will have power to spare.

28th November 2005, 02:43 AM	#6
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	AC12V from a transfomer still sufficient to power a gainclone,only the output power get reduced.

28th November 2005, 06:37 AM	#7
neutron7 diyAudio Member Join Date: Dec 2003 Location: Toronto Canada	if you do as Tja said you can use the transformers together to be equivelant to a 160 VA 24 + 24 which will work very well. you have to connect the 2 winding of each transformer in series, so you will need to make sure you know the phase.

28th November 2005, 10:54 AM	#9
tja diyAudio Member Join Date: Feb 2004 Location: Leiden	How did you wire the transformers? Take

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