SMALL SIZE OUTPUT TRANSFORMERS

el156 · 7th November 2010, 10:23 AM

Hi !
I found a small size transformer that can be interesting for low power amps. It is from RS, and code is 210-6475 , the primary impedance is between 4K - 15 K , the secundary 3 - 15 Ohms ,and allows 40mA DC, with 3.5 Watts max power. I tested it ,and the sound is OK for the size!
Perfect for a mini tube amplifier! The cost is about 10 Euros!
Hope is usefull
Silvino

CSlee · 7th November 2010, 10:37 AM

I just bought a pair of those for my 6DT5 SET, havnt fired it up yet, so im glad to hear that they work well. Plus they are really cheap!

Thanks for the info

Charlie

bigwill · 7th November 2010, 11:24 AM

Hmm, I think it's guitar amp time!

artosalo · 7th November 2010, 06:19 PM

Note the primary inductance, only 12,4 H.
This means that the actual primary impedance at 50 Hz is only 3,9 kohms and at 100 Hz 7,8 kohms respectively. With proper amount of NFB this could be used without too poor low frequency response.

Hi-Q · 7th November 2010, 09:53 PM

As this has a centre tapped primary, could this transformer be used in push-pull mode with suitable Triodes having a low Ra? I was thinking of something like the 5687. Might make a good headphone amplifier.

el156 · 8th November 2010, 06:36 PM

Hi !
I used this transformer in SE with ECC804 with the triodes in parallel for headphone amplifier,but i think it can be used in PP as well ! I will make a test in PP and post the results! I have some 6N7 ,maybe it worth a test!
Just for Fun
Silvino

CSlee · 8th November 2010, 08:19 PM

Hi Silvino,

I hooked these OTs to my SE 6DT5, and a few seconds after turn on there is an increasingly loud hum.

I thought it might be my wiring, so ive just rewired the whole amp, and am sill noticing the same hum. Im concerned it might be the transformers, as the old transformers were fine.

Have you noticed a problem like that?

Can you, or anyone offer some suggestions?

Thanks

Charlie

el156 · 9th November 2010, 10:39 AM

Quote:

Originally Posted by Charlie Slee

Hi Silvino,

I hooked these OTs to my SE 6DT5, and a few seconds after turn on there is an increasingly loud hum.

I thought it might be my wiring, so ive just rewired the whole amp, and am sill noticing the same hum. Im concerned it might be the transformers, as the old transformers were fine.

Have you noticed a problem like that?

Can you, or anyone offer some suggestions?

Thanks

Charlie

Hi Charlie!
No ! No hum at all! and as far as i know a OT doesnt make any hum ! If the wiring is ok,the hum has to come from somewhere else,i think ! Are the OTs mounted very close to the Power Transformer?

Silvino

CSlee · 9th November 2010, 10:44 AM

Hi Silvino,

Ive fitted the components into an old radio, so there isnt much space, but ive made sure that ive given the OTs enough room from the PT.

When testing the B+ on the primary the 'buzzing' intermitently gets worse and cuts out. Ive checked as much as I can, but my knowledge isnt good enough to diagnose the problem.

It seems there is some serious interference from somewhere.

Do you have any ideas?

Thanks

Charlie

CSlee · 9th November 2010, 10:46 AM

Ive checked for faulty diodes, caps, and ive moved the transformers around.

Ive also checked my wiring again, and to me it seems satisfactory.

Im a bit lost

7th November 2010, 10:23 AM	#1
el156 diyAudio Member Join Date: Apr 2010 Location: ALBUFEIRA ;PORTUGAL	SMALL SIZE OUTPUT TRANSFORMERS Hi ! I found a small size transformer that can be interesting for low power amps. It is from RS, and code is 210-6475 , the primary impedance is between 4K - 15 K , the secundary 3 - 15 Ohms ,and allows 40mA DC, with 3.5 Watts max power. I tested it ,and the sound is OK for the size! Perfect for a mini tube amplifier! The cost is about 10 Euros! Hope is usefull Silvino

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7th November 2010, 10:37 AM	#2
CSlee Clueless diyAudio Member Join Date: Mar 2009 Location: London	I just bought a pair of those for my 6DT5 SET, havnt fired it up yet, so im glad to hear that they work well. Plus they are really cheap! Thanks for the info Charlie

7th November 2010, 11:24 AM	#3
bigwill General Nuisance diyAudio Member Join Date: Dec 2004 Location: UK	Hmm, I think it's guitar amp time!

7th November 2010, 06:19 PM	#4
artosalo diyAudio Member Join Date: Feb 2010	Note the primary inductance, only 12,4 H. This means that the actual primary impedance at 50 Hz is only 3,9 kohms and at 100 Hz 7,8 kohms respectively. With proper amount of NFB this could be used without too poor low frequency response.

8th November 2010, 06:36 PM	#6
el156 diyAudio Member Join Date: Apr 2010 Location: ALBUFEIRA ;PORTUGAL	Hi ! I used this transformer in SE with ECC804 with the triodes in parallel for headphone amplifier,but i think it can be used in PP as well ! I will make a test in PP and post the results! I have some 6N7 ,maybe it worth a test! Just for Fun Silvino

8th November 2010, 08:19 PM	#7
CSlee Clueless diyAudio Member Join Date: Mar 2009 Location: London	Hi Silvino, I hooked these OTs to my SE 6DT5, and a few seconds after turn on there is an increasingly loud hum. I thought it might be my wiring, so ive just rewired the whole amp, and am sill noticing the same hum. Im concerned it might be the transformers, as the old transformers were fine. Have you noticed a problem like that? Can you, or anyone offer some suggestions? Thanks Charlie

9th November 2010, 10:44 AM	#9
CSlee Clueless diyAudio Member Join Date: Mar 2009 Location: London	Hi Silvino, Ive fitted the components into an old radio, so there isnt much space, but ive made sure that ive given the OTs enough room from the PT. When testing the B+ on the primary the 'buzzing' intermitently gets worse and cuts out. Ive checked as much as I can, but my knowledge isnt good enough to diagnose the problem. It seems there is some serious interference from somewhere. Do you have any ideas? Thanks Charlie

9th November 2010, 10:46 AM	#10
CSlee Clueless diyAudio Member Join Date: Mar 2009 Location: London	Ive checked for faulty diodes, caps, and ive moved the transformers around. Ive also checked my wiring again, and to me it seems satisfactory. Im a bit lost