I just got two from Ebay from this guy at $12.00 each. The auction is closed but he said he has plenty and is going to post some more.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2552227721&category=4665
If anyone wants his e-mail for direct sales, I am pretty sure he would set you up with as many as you want.
They are 44v centertap (22-0-22) and 150-200 VA, perfect for dual supply monoblocs.
Combine these with sample chips, scrounged heatsinks (or bent aluminum bar from Home Depot) and you have some potentially very nice GC's for purdy durn cheap.
GnD
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2552227721&category=4665
If anyone wants his e-mail for direct sales, I am pretty sure he would set you up with as many as you want.
They are 44v centertap (22-0-22) and 150-200 VA, perfect for dual supply monoblocs.
Combine these with sample chips, scrounged heatsinks (or bent aluminum bar from Home Depot) and you have some potentially very nice GC's for purdy durn cheap.
GnD
Cheap non-toroidal that's suitable
Parts Express has a 40vct 5a 200w transformer for 9.88
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Product_ID=119955&CATID=45
Getting closer to dumpster diving pricing, yo.
Parts Express has a 40vct 5a 200w transformer for 9.88
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Product_ID=119955&CATID=45
Getting closer to dumpster diving pricing, yo.
I was looking at those all yesterday...
I was going to buy some, but was concerned about the quality of them. The first question that pops to mind is why doesn't he know the VA rating on them? 150-200 still makes them perfect for GC's, it just makes me wonder how much variance there is in the other specs.
So, I decided to hold off until someone tried these. I guess now we'll know.
I'd love to do a fully dual-mono Joe Rasmussen tube buffered GC, but money is pretty tight right now and marque toroids like Plitron are way out of my ballpark.
I was going to order some Avel-Lindberg toroids yesterday for a single PSU. Specifically, their 330VA 115V/25-0-25V (P/N #Y236750) for the LM3875's and the 50VA 115V/25-0-25 (P/N #Y236206) for the buffer stage.
But, if these turn out to be reliable, then all bets are off and I'm going dual-mono
I was going to buy some, but was concerned about the quality of them. The first question that pops to mind is why doesn't he know the VA rating on them? 150-200 still makes them perfect for GC's, it just makes me wonder how much variance there is in the other specs.
So, I decided to hold off until someone tried these. I guess now we'll know.
I'd love to do a fully dual-mono Joe Rasmussen tube buffered GC, but money is pretty tight right now and marque toroids like Plitron are way out of my ballpark.
I was going to order some Avel-Lindberg toroids yesterday for a single PSU. Specifically, their 330VA 115V/25-0-25V (P/N #Y236750) for the LM3875's and the 50VA 115V/25-0-25 (P/N #Y236206) for the buffer stage.
But, if these turn out to be reliable, then all bets are off and I'm going dual-mono
PE X-formers
Just an FYI... I ordered one similar to these from PE (same style/ price, different VA rating) and it came with one or two broken (plastic) tabs at the tap points. (The unit is still functional.) PE happily and quickly replaced it, but the replacement arrived with broken tabs as well.
Ryan
Just an FYI... I ordered one similar to these from PE (same style/ price, different VA rating) and it came with one or two broken (plastic) tabs at the tap points. (The unit is still functional.) PE happily and quickly replaced it, but the replacement arrived with broken tabs as well.
Ryan
Thanks for the "head's up" RKH...
Rather than risk it, I'll just build mine with an overrated single PSU. This is going to be my first amp project and I need everything to go smoothly if I'm going to have any chance at success.
I guess the old adage "If it looks too good to be true, then...." applies here.
Rather than risk it, I'll just build mine with an overrated single PSU. This is going to be my first amp project and I need everything to go smoothly if I'm going to have any chance at success.
I guess the old adage "If it looks too good to be true, then...." applies here.
Re: Cheap non-toroidal that's suitable
Hardly....
If the louts at PartsExperss would bother to do a Google search, they might correctly describe these MCI Transformer Corp #4-07-8036 transformers as 36V CT @ 2.8amps, half the VA they tout.
http://www.mcitransformer.com/i_4-06_1.html
Still, a potentially nice transformer for gainclone use, albeit, at reduced power...
taterhead said:
Hardly....
If the louts at PartsExperss would bother to do a Google search, they might correctly describe these MCI Transformer Corp #4-07-8036 transformers as 36V CT @ 2.8amps, half the VA they tout.
http://www.mcitransformer.com/i_4-06_1.html
Still, a potentially nice transformer for gainclone use, albeit, at reduced power...
To answer the too-good-to-be-true warnings, these were overstock from an audio component (manufacturing) project.
My guess is (assuming that there is a lack of documentation) he is going by weight and wire guage for the VA.
BTW, this guy is a DIY amp-builder, and seemed to know what he was talking about.
There are lots of people who surplus entire lots of stuff like this on the cheap and sell them a few at a time on Ebay for a profit.
They seem pretty safe for dual mono's. At $12 each, I can live with it.
GnD
My guess is (assuming that there is a lack of documentation) he is going by weight and wire guage for the VA.
BTW, this guy is a DIY amp-builder, and seemed to know what he was talking about.
There are lots of people who surplus entire lots of stuff like this on the cheap and sell them a few at a time on Ebay for a profit.
They seem pretty safe for dual mono's. At $12 each, I can live with it.
GnD
It'd be nice to test one....
I'm no expert (actually a complete newbie), but wouldn't powering one up and measuring it's secondary under a "no load" situation tell us it's quiescent current consumption?
Then, we could simply compare it's "QCC" against some of the better know high-end boutique toroids of similar specs for an idea of it's relative efficiency and/or the quality of it's windings.
Of course, this won't tell us if the tx's hum or buzz.
How soon will you be getting yours, Graham?
Man, at that price I could go fully dual-mono for almost half the price of a single PSU
I'm no expert (actually a complete newbie), but wouldn't powering one up and measuring it's secondary under a "no load" situation tell us it's quiescent current consumption?
Then, we could simply compare it's "QCC" against some of the better know high-end boutique toroids of similar specs for an idea of it's relative efficiency and/or the quality of it's windings.
Of course, this won't tell us if the tx's hum or buzz.
How soon will you be getting yours, Graham?
Man, at that price I could go fully dual-mono for almost half the price of a single PSU
I got a pair of AVEL Y236503 160VA 22V+22V toroidals from Parts Express as well. I wanted to get the 250VA 25V+25V transformers but they were sold out.
I'm thinking that the 22v+22v should be fine for my 50wpc GC monoblocks. I should have thought more about saving money on the transformers cause spending $80 on two is like 50% of my GC budget.
I'm thinking that the 22v+22v should be fine for my 50wpc GC monoblocks. I should have thought more about saving money on the transformers cause spending $80 on two is like 50% of my GC budget.
I have ordered from this guy before. I have several transformers still sitting in the box. I'm in Los Angeles, CA if interested. I also ordered Avel Tororoidal Transformers from Parts Express which are what I am using currently.
GrahamnDodder said:
We ought to see if we can negotiate some sort of group price with him. If he can sell 10 or 15 of them directly to members of this forum, he might be willing to let them go for $10/ea. Otherwise, we're just bidding them up against each other on eBay.
Hey Idex, I'm in LA also (San Pedro).....
How do these cheapies compare to the Avel's that you are using?
Is there any chance you can power one up and test the secondaries for their "no load" current consumption?
It would be interesting to see if it's 15mA, 20mA, or whatever.
Don't feel bad houRman9, I'd need 4 of those Avel's if I'm going fully mono
Obviously, that's not going to happen, so either I go single PSU with Avel's or dual mono with these cheapies - $80 vs. $45 - it's almost no contest except I'd like to have 25V secondaries.
How do these cheapies compare to the Avel's that you are using?
Is there any chance you can power one up and test the secondaries for their "no load" current consumption?
It would be interesting to see if it's 15mA, 20mA, or whatever.
Don't feel bad houRman9, I'd need 4 of those Avel's if I'm going fully mono
Obviously, that's not going to happen, so either I go single PSU with Avel's or dual mono with these cheapies - $80 vs. $45 - it's almost no contest except I'd like to have 25V secondaries.
I ordered 5 of the MCI transformers from Part's Express awhile back and I received 2 of them with broken tabs. I just used epoxy to fix the broken tabs and that seemed to work well. I called MCI and they informed me that the the transformers were indeed 100VA instead of the 200VA that Part's Express stated. Still using 1 transformer for each channel it would only be $20 for a stereo gainclone. This is how I used the transformers and even using Allen-Bradley 1W resistors and cheap electrolytics, I still get wonderful sound from the gainclones that I have built. I get about 28 volts DC from the power supply with no load using MUR860 diodes and using the 1000 uF caps as close as I can get them to the LM3875 IC. I am using 4 ohm speakers and with the power supply voltage that I am using it works well. I find that the gainclone is a wonderfully simple amplifier to build and even with cheap parts it sounds better than alot of the cheaply built receivers on the market(ie. Sony,JVC,etc.) I will have to check out the toroidal transfomers that you listed Grahamn Dodder. Thanks for the tip.
Re: the toroids
The guys text on e-bay says that they were designed for 220 volts and that they put out 22-0-22 at 120v
so.. they were probably designed for 44-0-44 at 220v input
The question then is: If they were rated at say 300 VA at 220, what are they rated at 110? I think (and some appear to agree on other threads) that when you cut the input volts in half , you cut the VA capacity in half also. The secondaries aren't designed for higher amperage required for the 300 VA at a lower voltage.
If you want 300VA output at 22v rather than 44m, then you need twice the current in the secondary.
So... I suspect that the seller knows this and is adjusting their VA rating to corespond to the lower output volts. He isn't sure, so mentions a range. Is he doing it correctly? I don't know (I really don't because the above is just my opinion) BUT I don't think you can do it by weight, infact it might have to weigh twice what a transformer designed for 110 would weigh for the same VA.
BUT AGAIN: Often we get oversized transformers to insure a clean supply, and I can't help but think that for short surges caused by transients (in a class AB amp like the chip amps) the 220v input run at 110 would have much more capacity, The secondaries would eventually heat up if the high output were continuous though. It would help to know if the manufacturer has any markings on them to indicate what the VA rating was at 220v. Anyone have one in hand and notice any writing to this effect? Or an opinion of my opinion?
The guys text on e-bay says that they were designed for 220 volts and that they put out 22-0-22 at 120v
so.. they were probably designed for 44-0-44 at 220v input
The question then is: If they were rated at say 300 VA at 220, what are they rated at 110? I think (and some appear to agree on other threads) that when you cut the input volts in half , you cut the VA capacity in half also. The secondaries aren't designed for higher amperage required for the 300 VA at a lower voltage.
If you want 300VA output at 22v rather than 44m, then you need twice the current in the secondary.
So... I suspect that the seller knows this and is adjusting their VA rating to corespond to the lower output volts. He isn't sure, so mentions a range. Is he doing it correctly? I don't know (I really don't because the above is just my opinion) BUT I don't think you can do it by weight, infact it might have to weigh twice what a transformer designed for 110 would weigh for the same VA.
BUT AGAIN: Often we get oversized transformers to insure a clean supply, and I can't help but think that for short surges caused by transients (in a class AB amp like the chip amps) the 220v input run at 110 would have much more capacity, The secondaries would eventually heat up if the high output were continuous though. It would help to know if the manufacturer has any markings on them to indicate what the VA rating was at 220v. Anyone have one in hand and notice any writing to this effect? Or an opinion of my opinion?
Variac said:
Makes them ideal for an understressed supply... if we get a group buy, i'd be tempted to get at least a couple...
dave
They aren't understressed if they were rated 160VA at 220 volts
by the manufacturer.
I agree that they are probably just fine and yes I'm tempted
to get some too
by the manufacturer.
I agree that they are probably just fine and yes I'm tempted
to get some too
planet10 said:
I'd go in for 2 or 3, assuming the seller keeps the price at or not much above the $10-$15 he's been getting for them on eBay.
Warning: Avoid the Ebay Toroids I mentioned. This guy is a little "out there."
He can't even spec them accurately, yet demands you pay with a USPS money order (any other brand he sends right back to you) or, get this, cash through the mail.
Uh huh. Okay. That should have warned me.
I don't think he is even established enough to have an actual bank account. And he is moving his "product" 5 at a time. Hmm. Wonder where he got them. I'd be a little too nervous to put one of the mystery toroids into a GC.
Sorry for the goose chase.
🙄
GnD
He can't even spec them accurately, yet demands you pay with a USPS money order (any other brand he sends right back to you) or, get this, cash through the mail.
Uh huh. Okay. That should have warned me.
I don't think he is even established enough to have an actual bank account. And he is moving his "product" 5 at a time. Hmm. Wonder where he got them. I'd be a little too nervous to put one of the mystery toroids into a GC.
Sorry for the goose chase.
🙄
GnD
I guess there is something to the old saying...
"If it sounds too good to be true....."
Sorry to hear about your wild goose chase.
Hopefully, another budget opportunity will pop up for us, soon.
"If it sounds too good to be true....."
Sorry to hear about your wild goose chase.
Hopefully, another budget opportunity will pop up for us, soon.
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