I found a toroidal xfmr that somebody might be interested in at Fair Radio:
115 Dual 17V 5A 4.3x1.2 Torroidal 6 #4365-P1S2 $22.00
http://www.fairradio.com/lowvol.htm
This is a German made xfmr . I bought one a few years back from somwhere and just found it while digging around my "just in case someday I might need this" boxes. Might not be quite as high voltage as what Brian and Peter are using, but the Price is certainly right!
If anybody else orders one of these, could you post or e-mail me the color code for the windings, I've lost mine. I know, just hook it up with a low anp fuse and test it, but i'm too lazy to make a test clip lead for the 110.
Variac,
I ordered the largest of the three on your link:
enc-8-6 Aluminum Enclosure with ribbed 12.00
I figured that it since it was ribbed, my wife wouldn't complain about all these packages coming to the house!
I'm thinking about turning it 90 degrees so the ribs are on the sides and making a face plate out of bronze, if i can locate the right piece.
Thanks again for the tip on that!
Lee35210
(Boards finished, waiting on case and connectors
)
115 Dual 17V 5A 4.3x1.2 Torroidal 6 #4365-P1S2 $22.00
http://www.fairradio.com/lowvol.htm
This is a German made xfmr . I bought one a few years back from somwhere and just found it while digging around my "just in case someday I might need this" boxes. Might not be quite as high voltage as what Brian and Peter are using, but the Price is certainly right!
If anybody else orders one of these, could you post or e-mail me the color code for the windings, I've lost mine. I know, just hook it up with a low anp fuse and test it, but i'm too lazy to make a test clip lead for the 110.
Variac,
I ordered the largest of the three on your link:
enc-8-6 Aluminum Enclosure with ribbed 12.00
I figured that it since it was ribbed, my wife wouldn't complain about all these packages coming to the house!
I'm thinking about turning it 90 degrees so the ribs are on the sides and making a face plate out of bronze, if i can locate the right piece.
Thanks again for the tip on that!
Lee35210
(Boards finished, waiting on case and connectors
)
certainly qualifies as cheap parts... only a one off -- it was just over $10 CAD -- i'll have to bang out a few dents and drill some holes. The included trafo isn't GC suitable, but i have some surplus 18-0-18 225 VA Plitrons kicking around that are almost exactly the same size... room in here to put 4 amps w 2 trafos 
even room for XOs maybe.
dave
even room for XOs maybe.dave
Attachments
I interpret dual as having 2 outputs of 17 volts.
If so, thats 4 wires out. that's how the transformers Brian is using are, and it will wire right up.
So the total output is 2*17*5= 170VA which is maybe a bit low
for 2 channels, but would no doubt work fine in ordinary use.
I think that matches the size mentioned about right.
Are my assumptions right Lee?
Using one per channel is more than enough- Real luxury monoblocks
Now , I wish I could get a definitive opinion on the easiest way to wire up transformers with a center tap, which isn't shown in the original online manual. Do you have an opinion J-P ? (P.S. no knobs have appeared yet )
If so, thats 4 wires out. that's how the transformers Brian is using are, and it will wire right up.
So the total output is 2*17*5= 170VA which is maybe a bit low
for 2 channels, but would no doubt work fine in ordinary use.
I think that matches the size mentioned about right.
Are my assumptions right Lee?
Using one per channel is more than enough- Real luxury monoblocks
Now , I wish I could get a definitive opinion on the easiest way to wire up transformers with a center tap, which isn't shown in the original online manual. Do you have an opinion J-P ? (P.S. no knobs have appeared yet )
BZO,
weight and size is correct. Current is per winding, hence the weight. I know about size because I had mine sitting on a CDR spindle case last night. And it is a HEAVY sucker!
Uvobee,
This xfmr has dual sec windings, so no CT is necessary.
| |--------17
| |
| |---------0
|
| |---------17
| |
| |--------0
Lee35210
weight and size is correct. Current is per winding, hence the weight. I know about size because I had mine sitting on a CDR spindle case last night. And it is a HEAVY sucker!
Uvobee,
This xfmr has dual sec windings, so no CT is necessary.
| |--------17
| |
| |---------0
|
| |---------17
| |
| |--------0
Lee35210
Sorry Variac, missed your post during my drawing time. Your dead on as usual. I'm building mine to drive my Stax Headphones, so I don't for see needing gobs of watts. May drive speakers with it, but 10a seems plenty, just lower power out due to lower rail vltges. BUt hey, I think I paid about $15USD for mine ~10 yrs ago!
~$50 for an Avel or more for a Victoria is not an option at this point. (my TT needs a new belt)
Lee35210
~$50 for an Avel or more for a Victoria is not an option at this point. (my TT needs a new belt)
Lee35210
Parmetal:
First I wasted about a week trying e-mail. A total waste of time...
Then I got the woman on the phone. She was pleasant, but needed her boss to answer questions about the optional thicker front plate.
She told me he said that it would be a solid 2 weeks because they had to process the order, forward it to new jersey, and ship it from there.
They don't appear to be organized for really low quantities from people they aren't used to working with. I requested handles as an upgrade, and had to repeat that I wanted silver with the black face plate, but once she accepted it , that was fine.
All in all, I'm optimistic- the value seems good, and I think it will look good. Also , half the price of Peter's. I set my budget at less than half Peters, because if it got to be close to his price, better to go with his which is so nice!
I don't remember menetion of any confirming call so I can't help you on that. Maybe best t o wait a couple of days , then call them.
First I wasted about a week trying e-mail. A total waste of time...
Then I got the woman on the phone. She was pleasant, but needed her boss to answer questions about the optional thicker front plate.
She told me he said that it would be a solid 2 weeks because they had to process the order, forward it to new jersey, and ship it from there.
They don't appear to be organized for really low quantities from people they aren't used to working with. I requested handles as an upgrade, and had to repeat that I wanted silver with the black face plate, but once she accepted it , that was fine.
All in all, I'm optimistic- the value seems good, and I think it will look good. Also , half the price of Peter's. I set my budget at less than half Peters, because if it got to be close to his price, better to go with his which is so nice!
I don't remember menetion of any confirming call so I can't help you on that. Maybe best t o wait a couple of days , then call them.
Did you order this tranny?
Hey Variac,
I just got around to looking at it. It looks interesting!--did you order 1 (or more)? I am curious how it looks. Also, if you ordered 1, what was the shipping--the site says $5.95 for $20 or less, but it seems too cheap to ship 12 lbs of trannys (2 of 'em) from the midwest. These are looking more interesting every min. By the by, all the expensive units seem to use toroid trannys insead of open frame ones--anyone know why?
Thanks,
Bret Morrow
Variac said:
Hey Variac,
I just got around to looking at it. It looks interesting!--did you order 1 (or more)? I am curious how it looks. Also, if you ordered 1, what was the shipping--the site says $5.95 for $20 or less, but it seems too cheap to ship 12 lbs of trannys (2 of 'em) from the midwest. These are looking more interesting every min. By the by, all the expensive units seem to use toroid trannys insead of open frame ones--anyone know why?
Thanks,
Bret Morrow
, I= the smartie. Anyways I got a invoice # from them and from the sounds of it I will see the cases in about 3 weeks.
Hey Brett,
Best I can understand, you need 2 of those transformers to get v+, v- and 2 neutrals. OR something like that. What Uvodee said about 2 wire amps DOES apply here.
So you need 2 transformers just to make it work, with both channels paralled as Brian's basic approach.
i.e. If you want monoblocks you need 4 transformers ($40)The extra stuff- switches and connectors are what make this a deal-plus the shipping- see below.
Toroids have some advantages- more compact, less stray magnetic fields, better regulation. BUT some people prefer the classic open frame. Unless they are something exotic, open frames are cheaper usually
Their shipping policy is great!!! It's by value, not weight. The 2 JBL 15" drivers I am constantly mentioning that I got from them, cost me $15 to ship both!!!!!!!!!!!!!!!! (about 55 lbs)
A slightly lighter pair of 15" drivers from Parts Express cost me $50 to ship.
Best I can understand, you need 2 of those transformers to get v+, v- and 2 neutrals. OR something like that. What Uvodee said about 2 wire amps DOES apply here.
So you need 2 transformers just to make it work, with both channels paralled as Brian's basic approach.
i.e. If you want monoblocks you need 4 transformers ($40)The extra stuff- switches and connectors are what make this a deal-plus the shipping- see below.
Toroids have some advantages- more compact, less stray magnetic fields, better regulation. BUT some people prefer the classic open frame. Unless they are something exotic, open frames are cheaper usually
Their shipping policy is great!!! It's by value, not weight. The 2 JBL 15" drivers I am constantly mentioning that I got from them, cost me $15 to ship both!!!!!!!!!!!!!!!! (about 55 lbs)
A slightly lighter pair of 15" drivers from Parts Express cost me $50 to ship.
THANK YOU THANK YOU THANK YOU
I really appreciate that Variac
I have been trying to explain (but I'm not good at it cause I am not an EE, I did learn enough on diyaudio though to see how a gc power supply works) but some people are still not grasping it.
btw: look at tha other thread as well gc power supply trouble ; same thing they think overthere that with a 2 wire trannie the gc will be working ar a 4 wire will serve 2 gc's.
one needs a pos, a neg and a 0 volt wire AND prefereably not higher than 25 volts measured between the pos and neg. Cause you reach the max of the chip. In my experience, so far I have made 5 gc's not including the groupbuy, which I have laying here in fornt of me, my worst sounding result was the set up with the power from a 25 volt 8 amp transf. = the actual read out says 27 volts before and 41 after rectifier and I think the 3875's don't appreciate that .....
the difference is very present , even I can hear it.
I really appreciate that Variac
I have been trying to explain (but I'm not good at it cause I am not an EE, I did learn enough on diyaudio though to see how a gc power supply works) but some people are still not grasping it.
btw: look at tha other thread as well gc power supply trouble ; same thing they think overthere that with a 2 wire trannie the gc will be working ar a 4 wire will serve 2 gc's.
one needs a pos, a neg and a 0 volt wire AND prefereably not higher than 25 volts measured between the pos and neg. Cause you reach the max of the chip. In my experience, so far I have made 5 gc's not including the groupbuy, which I have laying here in fornt of me, my worst sounding result was the set up with the power from a 25 volt 8 amp transf. = the actual read out says 27 volts before and 41 after rectifier and I think the 3875's don't appreciate that .....
the difference is very present , even I can hear it.
Variac said:
Actually, Brians boards are made for a Transformer that has
2 pairs of output wires. My understanding is that the 2 pairs are in parallel. Each pair has a hot and neutral wire.
The way his bridge is set up, I think that the two hot wires are what create the Plus and Minus 25 volts . The two neutral wires are together equivalent to the center tap, but are kept separate.
I think if you measure between the pos and neg you will get 50 volts.
The way Brian gets 2 channels off of one bridge is that he just hooks them up in parallel. If you have enough power supply, I guess you could parallel a bunch of the amp cards onto the outputs of the Power board.
This is the best I can figure out. This proves how actually doing things helps one learn. One can think that one has a good grasp of what's going on, but when the building starts one discovers that there are big gaps in their knowledge.
If you have successfully hooked a center tapped transfpormer to Brian's power supply board , I need to hear about it right away!!!
2 pairs of output wires. My understanding is that the 2 pairs are in parallel. Each pair has a hot and neutral wire.
The way his bridge is set up, I think that the two hot wires are what create the Plus and Minus 25 volts . The two neutral wires are together equivalent to the center tap, but are kept separate.
I think if you measure between the pos and neg you will get 50 volts.
The way Brian gets 2 channels off of one bridge is that he just hooks them up in parallel. If you have enough power supply, I guess you could parallel a bunch of the amp cards onto the outputs of the Power board.
This is the best I can figure out. This proves how actually doing things helps one learn. One can think that one has a good grasp of what's going on, but when the building starts one discovers that there are big gaps in their knowledge.
If you have successfully hooked a center tapped transfpormer to Brian's power supply board , I need to hear about it right away!!!
Re: THANK YOU THANK YOU THANK YOU
WOW perfect timing! I went out for a run to contemplate what Variac said & considered compose an email directly to you with my questions after Variac mentioned you and I remembered reading about you starting up your first GC a couple of months ago. When I get back new post from you--great!!! I hope you don't mind if I pick your brain, I'm still am a bit confused--likely because I'm not an EE, an E, or even an e! I read through the other post (GC power supply trouble) and this all seems to make sense for a lot of trannys, that have 2 wire secondaries out (e.g. this discription of a tranny cut 'n'pasted from www.sciplus.com part #26271)
"Once you plug this transformer into a line cord with an IEC female end (not included), it will put out 25 VAC at 7.5 amp through wires 1 and 2, (SNIP)."
In that tranny the difference between wire 1 & 2 is 25 VAC (right?) and this would work for a GC. Although from what you posted--this maybe too much for a GC (bummer, it was a good deal). How would you use something that has its power listed as say 20-0-20? (e.g. from www.partsexpress.com part #129-030)
"Center tapped power transformer originally made for use in medium power audio amplifiers. Features 40 VAC (20-0-20) center tapped secondary, rated at 5A (200W)"
Specifically, like Variac, I'm using BrianGT's PCB and the inputs doesn't seem to match up at least to me. The 2 hot wires are + and -20 VAC, respectively--how does this connect to a PCB that seems to want 2 neutrals & 2 hots?
Thanks in advance!,
Bret Morrow
uvodee said:
WOW perfect timing! I went out for a run to contemplate what Variac said & considered compose an email directly to you with my questions after Variac mentioned you and I remembered reading about you starting up your first GC a couple of months ago. When I get back new post from you--great!!! I hope you don't mind if I pick your brain, I'm still am a bit confused--likely because I'm not an EE, an E, or even an e! I read through the other post (GC power supply trouble) and this all seems to make sense for a lot of trannys, that have 2 wire secondaries out (e.g. this discription of a tranny cut 'n'pasted from www.sciplus.com part #26271)
"Once you plug this transformer into a line cord with an IEC female end (not included), it will put out 25 VAC at 7.5 amp through wires 1 and 2, (SNIP)."
In that tranny the difference between wire 1 & 2 is 25 VAC (right?) and this would work for a GC. Although from what you posted--this maybe too much for a GC (bummer, it was a good deal). How would you use something that has its power listed as say 20-0-20? (e.g. from www.partsexpress.com part #129-030)
"Center tapped power transformer originally made for use in medium power audio amplifiers. Features 40 VAC (20-0-20) center tapped secondary, rated at 5A (200W)"
Specifically, like Variac, I'm using BrianGT's PCB and the inputs doesn't seem to match up at least to me. The 2 hot wires are + and -20 VAC, respectively--how does this connect to a PCB that seems to want 2 neutrals & 2 hots?
Thanks in advance!,
Bret Morrow
A little more info....
I don't have any EE's at all either.
We sure need some EEEEEEs right now, Please comment.
At the moment it's blind leading the blind
Various people are using 25v transformers. Some say it's a bit high, but I'd say the majority of people are using that voltage.
The important thing is that you can't just use the Am Sci amp by itself, you need 2 of them I think.
This is the distinction I've tried to make. The Parts Express toroids have TWO PAIRS of outputs- A total of 4 wires out.
Other transformers like the Am Sci have ONE pair of outputs- a total of 2 wires out.
BUT you CAN combine two of the Am Sci to create the equivalent
of a transformer with 4 wires out.
The very important thing I THINK is that there isn't a pair of wires
from the transformer that go to one amp, then the other pair goes to the other, INSTEAD, you need at least 3 or 4 wires for just ONE amp. Yoiu then in effect just add amps in parallel to the same wires.
Anyway that's how I see it.....
I don't have any EE's at all either.
We sure need some EEEEEEs right now, Please comment.
At the moment it's blind leading the blind
Various people are using 25v transformers. Some say it's a bit high, but I'd say the majority of people are using that voltage.
The important thing is that you can't just use the Am Sci amp by itself, you need 2 of them I think.
This is the distinction I've tried to make. The Parts Express toroids have TWO PAIRS of outputs- A total of 4 wires out.
Other transformers like the Am Sci have ONE pair of outputs- a total of 2 wires out.
BUT you CAN combine two of the Am Sci to create the equivalent
of a transformer with 4 wires out.
The very important thing I THINK is that there isn't a pair of wires
from the transformer that go to one amp, then the other pair goes to the other, INSTEAD, you need at least 3 or 4 wires for just ONE amp. Yoiu then in effect just add amps in parallel to the same wires.
Anyway that's how I see it.....
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.