Hammond SE Transformer question

alk · 8th May 2004, 10:36 AM

Hi,
I have just build my first tube amp and i was designing a nice rosewood box for it when i found my output transformer was just too big for this little amp- my mistake. I wanted to do a little and cute box.... The trafo is a hammond 125ESE. I have seen the smallest of the SE line rating 3W really cheap (Hammond ASE) and as my amp puts out 2w am thinking of buying it and use the ESE(15w) for a guitar amp(the amp i made is too clean for electric guitar).
My question is this: will i miss something in the sound?
I am happy with its sound but i plan to make another amp with some Russian valves i saw in the future. Will i repent if i replace the transformer? If somebody tells me the sound would change for worse i would not do it.
I'm not an audiophile but my ears are not fooled easily.
Thanks

baggystevo82 · 8th May 2004, 11:02 AM

Hi,
So long as the primary resistance and the secondary taps are correct it should be fine. I think as far as transformers go, all other things being equal, the smaller they are the better the frequency response will be, though I dont know if this will be noticable. If it's rated 3W, has the right primary resistance and the right secondary taps, and is cheap, Id go for it. If you decide you dont like it you can always swap it back as you say you can get them cheap

I'm a beginner myself so dont take any of this as fact!! I'd wait to see what everyone else has to say on it...
Good luck,
Steve

alk · 8th May 2004, 01:56 PM

Thanks Steve ...it is also my opinion but i'm also a beginner. People seem to relate big sound to big iron...i dunno

fdegrove · 8th May 2004, 02:02 PM

Hi,

Quote:

the smaller they are the better the frequency response will be,

At what end of the spectrum?

There's alot more than physical size to a good OPT but you just can't get any decent low frequency response out of a miniature sized one...

Cheers,

baggystevo82 · 8th May 2004, 02:04 PM

Hi,
Big sound needs big iron due to high power, or the transformer would get too hot. In the case of single ended amps they also have to cope with higher DC flow on the primaries. Your amp is 2W and using a huge opt won't change that.
Just googled for that transformer and apparently the 125ESE can cope with 80mA DC on its primaries and is more suited to single ended KT88 kind of power, which seems a little overkill. I think you should go with the ASE

Steve

baggystevo82 · 8th May 2004, 02:08 PM

Quote:

Originally posted by fdegrove
At what end of the spectrum?

There's alot more than physical size to a good OPT but you just can't get any decent low frequency response out of a miniature sized one...

I was on about losing top end with really big opt. Im just quoting out of Morgan Jones's book here, I haven't any actual experience apart from the amp I just built. I remember seeing on the sowter site some frequency response curves for their opt, maybe hammond do the same?
Steve

baggystevo82 · 8th May 2004, 02:17 PM

Hmmmm, it says on the hammond site that none of the 125 series are for hifi use

Steve

alk · 8th May 2004, 02:56 PM

Hi Steve, here they don't think so.
http://members.myactv.net/~je2a3/125ESE.htm

baggystevo82 · 8th May 2004, 03:01 PM

Well theyre cheap anyway so you may as well try em...
According to hammond their response is 100Hz to 15KHz @-1dB and their hifi series is rated 20Hz to 20KHz @-1dB, dunno if you would hear a difference though.
Steve

baggystevo82 · 8th May 2004, 03:06 PM

Hi again,
I just read through a bit more of that link. I think they went for that one as you can configure it for lots of different primary resistances. It is a bit of a worry that two transformers acted so differently though

Maybe if you bought more than you need (if they are really really cheap) and picked out the good ones?
Steve

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8th May 2004, 11:02 AM	#2
baggystevo82 diyAudio Member Join Date: Dec 2003 Location: Herefordshire	Hi, So long as the primary resistance and the secondary taps are correct it should be fine. I think as far as transformers go, all other things being equal, the smaller they are the better the frequency response will be, though I dont know if this will be noticable. If it's rated 3W, has the right primary resistance and the right secondary taps, and is cheap, Id go for it. If you decide you dont like it you can always swap it back as you say you can get them cheap I'm a beginner myself so dont take any of this as fact!! I'd wait to see what everyone else has to say on it... Good luck, Steve

8th May 2004, 01:56 PM	#3
alk diyAudio Member Join Date: Apr 2004 Location: tiny place	Thanks Steve ...it is also my opinion but i'm also a beginner. People seem to relate big sound to big iron...i dunno

8th May 2004, 02:04 PM	#5
baggystevo82 diyAudio Member Join Date: Dec 2003 Location: Herefordshire	Hi, Big sound needs big iron due to high power, or the transformer would get too hot. In the case of single ended amps they also have to cope with higher DC flow on the primaries. Your amp is 2W and using a huge opt won't change that. Just googled for that transformer and apparently the 125ESE can cope with 80mA DC on its primaries and is more suited to single ended KT88 kind of power, which seems a little overkill. I think you should go with the ASE Steve

8th May 2004, 02:17 PM	#7
baggystevo82 diyAudio Member Join Date: Dec 2003 Location: Herefordshire	Hmmmm, it says on the hammond site that none of the 125 series are for hifi use Steve

8th May 2004, 02:56 PM	#8
alk diyAudio Member Join Date: Apr 2004 Location: tiny place	Hi Steve, here they don't think so. http://members.myactv.net/~je2a3/125ESE.htm

8th May 2004, 03:01 PM	#9
baggystevo82 diyAudio Member Join Date: Dec 2003 Location: Herefordshire	Well theyre cheap anyway so you may as well try em... According to hammond their response is 100Hz to 15KHz @-1dB and their hifi series is rated 20Hz to 20KHz @-1dB, dunno if you would hear a difference though. Steve

8th May 2004, 03:06 PM	#10
baggystevo82 diyAudio Member Join Date: Dec 2003 Location: Herefordshire	Hi again, I just read through a bit more of that link. I think they went for that one as you can configure it for lots of different primary resistances. It is a bit of a worry that two transformers acted so differently though Maybe if you bought more than you need (if they are really really cheap) and picked out the good ones? Steve

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