transformer for gainclone

SQ Kid · 1st April 2003, 11:03 PM

hey, been noticing this amp has been the talk of this forum, so i figured i'd give it a shot. inexpensive is a good word for a college kid to hear

. i'm ordering all of my parts through parts express (unless someone knows a place thats cheaper for us here in the US). the only thing i'm not too sure about is the transformer. they have 2 that look like they could do the job, but just want to make sure.

part #129-030 40v CT power transformer (20-0-20). however its only rated at 5A. i am using one power supply for two amps, so is this too low?

part# 120-225 48v CT power transformer (24-0-24). this one is only rated at 3A. is that too little?

anyone have a better idea for something inexpensive? i would like to keep the trans below $25. anything good at radio shack? any better online suppliers? thanks very much for your help.

blip · 2nd April 2003, 02:26 AM

That's funny... This college student was thinking about the exact same question and the exact same concern about expenses!

Here is my read .(primarily from what I've gathered in the monster gain clone thread) I think that the 5a version is better because it
comes closer than to the 18-0-18 ideal that Peter Daniel's talks about. (Of course he has said that it isn't always better, and may produce too much bass. But hey, I'll admit to being a closet bass head so I don't mind that too much.

)

Anyway, hopefully a more experienced member than I will answer this more definitively.

JAZZ2250 · 2nd April 2003, 03:49 AM

I tried 129-030 for both channels of my gainclone and it worked OK.
Everybody is using massive transformers much higher than 200VA. However, as long as you don't want to rock your whole house, transformers with lower rating will be just fine. I even tried toroidal transformers, which I got from AllElectronics (18-0-18V @ 2-3 A), with great success. Of course, they were pretty cheap. But, they are discontinued unfortunately.
You could also try ones from Apexjr.com. They have some cheap transformers which, I think, are surplus items.

Good luck.

Philo · 2nd April 2003, 01:46 PM

Not everyone is using huge brand name transformers in their gainclones. I have 2x 120VA (2x18 secondaries ea) toroids and they are easily sufficient. Two transformers usually are more expensive but small ones are usually easier to find cheaply in surplus shops. Look around in your local industrial and electronic surplus shops for transformers. Ask them what they have, sometimes you strike gold.

SQ Kid · 3rd April 2003, 04:27 AM

any other ideas? sites? thanks

Apex Jr · 4th April 2003, 11:02 PM

Hi....
I might have a few you might be interested in.
Small quantitys and not listed on the website
Toroid.... 44Vct 250Va $27.50 I think only 2 left
E I core 35Vct 4 amp Triad $12.50ea about 6 in stock
Listed on the clearance page
E I core 48Vct 7A and 24Vct $9.95 only 10 left (BL1733A)
picture on website
Steve @ Apex Jr

swirv · 5th April 2003, 01:26 PM

I have this transformer from apexJr. Should this work well?

Its 14-0-14 and 24-0-24. I had planed on using the 14v side for a few lm3875s 80hz up and the 24v side for two lm3886's for subs.

blip · 6th April 2003, 01:12 AM

Quote:

Originally posted by swirv
I have this transformer from apexJr. Should this work well?

Its 14-0-14 and 24-0-24. I had planed on using the 14v side for a few lm3875s 80hz up and the 24v side for two lm3886's for subs.

What is the amp rating on the two lines?

swirv · 6th April 2003, 03:43 PM

Primary 120V Secondary 48VCT 7A & 28VCT 3A

blip · 6th April 2003, 11:35 PM

The 28 VCT line has enough current but it is a little low voltage. I'll check the minimum rated voltage later.

The other line will be just fine.

2nd April 2003, 01:46 PM	#4
Philo diyAudio Member Join Date: Jul 2002 Location: Ever sunny San Diego	Not everyone is using huge brand name transformers in their gainclones. I have 2x 120VA (2x18 secondaries ea) toroids and they are easily sufficient. Two transformers usually are more expensive but small ones are usually easier to find cheaply in surplus shops. Look around in your local industrial and electronic surplus shops for transformers. Ask them what they have, sometimes you strike gold. __________________ Philip "If you didn't make it with your own two hands, its not really yours".

4th April 2003, 11:02 PM	#6
Apex Jr diyAudio Member Join Date: Jun 2002 Location: Torrance, Calif	Transformer's Hi.... I might have a few you might be interested in. Small quantitys and not listed on the website Toroid.... 44Vct 250Va $27.50 I think only 2 left E I core 35Vct 4 amp Triad $12.50ea about 6 in stock Listed on the clearance page E I core 48Vct 7A and 24Vct $9.95 only 10 left (BL1733A) picture on website Steve @ Apex Jr

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1st April 2003, 11:03 PM	#1
SQ Kid diyAudio Member Join Date: Apr 2003 Location: MA	transformer for gainclone hey, been noticing this amp has been the talk of this forum, so i figured i'd give it a shot. inexpensive is a good word for a college kid to hear . i'm ordering all of my parts through parts express (unless someone knows a place thats cheaper for us here in the US). the only thing i'm not too sure about is the transformer. they have 2 that look like they could do the job, but just want to make sure. part #129-030 40v CT power transformer (20-0-20). however its only rated at 5A. i am using one power supply for two amps, so is this too low? part# 120-225 48v CT power transformer (24-0-24). this one is only rated at 3A. is that too little? anyone have a better idea for something inexpensive? i would like to keep the trans below $25. anything good at radio shack? any better online suppliers? thanks very much for your help.

2nd April 2003, 02:26 AM	#2
blip diyAudio Member Join Date: Mar 2003 Location: Salem, OR	That's funny... This college student was thinking about the exact same question and the exact same concern about expenses! Here is my read .(primarily from what I've gathered in the monster gain clone thread) I think that the 5a version is better because it comes closer than to the 18-0-18 ideal that Peter Daniel's talks about. (Of course he has said that it isn't always better, and may produce too much bass. But hey, I'll admit to being a closet bass head so I don't mind that too much. ) Anyway, hopefully a more experienced member than I will answer this more definitively.

2nd April 2003, 03:49 AM	#3
JAZZ2250 diyAudio Member Join Date: Mar 2002 Location: Seoul. Korea	I tried 129-030 for both channels of my gainclone and it worked OK. Everybody is using massive transformers much higher than 200VA. However, as long as you don't want to rock your whole house, transformers with lower rating will be just fine. I even tried toroidal transformers, which I got from AllElectronics (18-0-18V @ 2-3 A), with great success. Of course, they were pretty cheap. But, they are discontinued unfortunately. You could also try ones from Apexjr.com. They have some cheap transformers which, I think, are surplus items. Good luck.

3rd April 2003, 04:27 AM	#5
SQ Kid diyAudio Member Join Date: Apr 2003 Location: MA	any other ideas? sites? thanks

5th April 2003, 01:26 PM	#7
swirv diyAudio Member Join Date: Aug 2002 Location: South Carolina	I have this transformer from apexJr. Should this work well? Its 14-0-14 and 24-0-24. I had planed on using the 14v side for a few lm3875s 80hz up and the 24v side for two lm3886's for subs.

6th April 2003, 03:43 PM	#9
swirv diyAudio Member Join Date: Aug 2002 Location: South Carolina	Primary 120V Secondary 48VCT 7A & 28VCT 3A

6th April 2003, 11:35 PM	#10
blip diyAudio Member Join Date: Mar 2003 Location: Salem, OR	The 28 VCT line has enough current but it is a little low voltage. I'll check the minimum rated voltage later. The other line will be just fine.