Power Transformers available
Hi:
I have moved the listing for my transformers for sale to:
http://www.geocities.com/dmfraser77/parts4sale.html
Please have a look for some power transformers suitable for the UcD180 amplifiers.
Hi:
I have moved the listing for my transformers for sale to:
http://www.geocities.com/dmfraser77/parts4sale.html
Please have a look for some power transformers suitable for the UcD180 amplifiers.
quick and dirty
Hi,
here you may find my first approach to an 4-channel amp with UcDs. It is foreseen to drive the smaller 3-way-speaker during its "tuning", using a behringer dsp crossover. After that it may be used by my son for his band, therefore the 19" case.
Please forgive me the dirty design, I was very keen to hear both channels together. First I was surprised about the very different sound, compared to my simple Technics SU-VX500 - until I noted the activated loudness.
After that I was not able to spot a significant difference, which I could describe well. The main reason was the lack of a A/B-switch behind the amps. The bigger speakers are not well suited for that comparison, too.
But I liked the Japanese drums of Ondekoza very much at that volume level!
After a while I noted the remarkable temperature of the output chokes, more than 50 degC. They seem to be the hottest, most lossy part of the whole module.
I wait for the gold plated XLRs still. The volume control I realised with double log pots in series, it works satisfactory.
The PS is not ideal, the next will have only double 2way-rectifiers instead of bridges. The 330W-transformer seems to be symmetrical up to 0.1V. I should implement a softstart too, now I need 4A-fuses on the primary side minimum.
A thought about caps: I tried to find cheap ones with low ESR and small dissipation factor. I believe, these are their main characteristics for audio purposes. On that score aerovox and other "audiophile" caps are not the best. Bruno described already, that the ESL of the standard caps is low enough, so why slit foil and T-caps? Is anybody really sure to hear that? Remember Bruno's blind test of PS-caps together with his father.
Thank you, Bruno, Jan-Peter, JohnW and all the others for your useful hints and explanations.
edit:
I connected the mute-contact to ground hard-wired. Sometimes there is a remarkable "thunder" while switching on. A few seconds after switch off a small chirp occurs. I do only hear noise, if I creep into the tweeters, 20cm away I don't hear anything - very good! I like the UcDs very much and hope, they and their successors will conquer the audio scene.
Best regards, Timo
Hi,
here you may find my first approach to an 4-channel amp with UcDs. It is foreseen to drive the smaller 3-way-speaker during its "tuning", using a behringer dsp crossover. After that it may be used by my son for his band, therefore the 19" case.
Please forgive me the dirty design, I was very keen to hear both channels together. First I was surprised about the very different sound, compared to my simple Technics SU-VX500 - until I noted the activated loudness.
After that I was not able to spot a significant difference, which I could describe well. The main reason was the lack of a A/B-switch behind the amps. The bigger speakers are not well suited for that comparison, too.But I liked the Japanese drums of Ondekoza very much at that volume level!
After a while I noted the remarkable temperature of the output chokes, more than 50 degC. They seem to be the hottest, most lossy part of the whole module.
I wait for the gold plated XLRs still. The volume control I realised with double log pots in series, it works satisfactory.
The PS is not ideal, the next will have only double 2way-rectifiers instead of bridges. The 330W-transformer seems to be symmetrical up to 0.1V. I should implement a softstart too, now I need 4A-fuses on the primary side minimum.
A thought about caps: I tried to find cheap ones with low ESR and small dissipation factor. I believe, these are their main characteristics for audio purposes. On that score aerovox and other "audiophile" caps are not the best. Bruno described already, that the ESL of the standard caps is low enough, so why slit foil and T-caps? Is anybody really sure to hear that? Remember Bruno's blind test of PS-caps together with his father.
Thank you, Bruno, Jan-Peter, JohnW and all the others for your useful hints and explanations.
edit:
I connected the mute-contact to ground hard-wired. Sometimes there is a remarkable "thunder" while switching on. A few seconds after switch off a small chirp occurs. I do only hear noise, if I creep into the tweeters, 20cm away I don't hear anything - very good! I like the UcDs very much and hope, they and their successors will conquer the audio scene.
Best regards, Timo
edit button is gone...
Forgot to add, that I used Schottky rectifiers MBR10100 (yes, with small Cs in parallel). I hope, the Schottkies perform even better than fast rectifiers due to their lack of recovery time issues. Additionally, they have lower Vf. The results should be a lower supply output resistance and less possibility of spike generation (will check that with a scope sometimes, or the input ac-coupled to the supply
).
regards, Timo
Forgot to add, that I used Schottky rectifiers MBR10100 (yes, with small Cs in parallel). I hope, the Schottkies perform even better than fast rectifiers due to their lack of recovery time issues. Additionally, they have lower Vf. The results should be a lower supply output resistance and less possibility of spike generation (will check that with a scope sometimes, or the input ac-coupled to the supply
).regards, Timo
finally finished the casework ...
the top case is just a source selector and volume pot, i still have to build a decent pre.
why isn't the image being shown? i did enclose the link in img tags !?
the top case is just a source selector and volume pot, i still have to build a decent pre.
An externally hosted image should be here but it was not working when we last tested it.
why isn't the image being shown? i did enclose the link in img tags !?
here ya go
My original plan was to mount the xformer in the centre and the psu caps bbehind it, also in the centre. That way you can have really short wires from the psu to the modules. Alas, i miscalculated the size of the psu board by a centimetre and it just wouldn't fit nicely.
a bit messy. I think Usvr posted a pic of the internals of his amp somewhere around page 70 of this thread.
found usvr's post: http://www.diyaudio.com/forums/showthread.php?postid=462744#post462744
My original plan was to mount the xformer in the centre and the psu caps bbehind it, also in the centre. That way you can have really short wires from the psu to the modules. Alas, i miscalculated the size of the psu board by a centimetre and it just wouldn't fit nicely.
a bit messy. I think Usvr posted a pic of the internals of his amp somewhere around page 70 of this thread.
An externally hosted image should be here but it was not working when we last tested it.
found usvr's post: http://www.diyaudio.com/forums/showthread.php?postid=462744#post462744
matjans said:the first link in my previous post is *my* amp.
Oh, I see! Sorry about that, looked only at the second link...
Yes, that is what I thought you must have done. Did you just glue them on to the outsides then?
How warm do the sides of the case get when it is running full tilt?
[I need quite a few of these amps and was hoping to stack them in close proximity to each other. On my Zappulse I used a sheet of Alu on the base, which is attached to the steel bottom and they have trouble dissipating all the heat (it gets about 50-60C on the top side of the case). I am curious as to whether by attaching them to the sides which are Alu of this case you keep the temp *easily* under control, or *only just* under control? Basically, once I stack 4 of these on top of each other and then put them in an equip rack with a door (to keep the baby out), then I don't want them to melt...]
UrSv: What is the spec of your powersupply? I see two torroids - do you find the double torroids makes a useful difference? What rating are they?
(I was going to get single 500-800Va for each stereo amp, but then I saw the small price incremental on the 1000Va ones, so was considering one of those. However, farnell have encapsulated 500Va transformers and I was curious as to whether these might be better for our application?
http://www.farnell.com/datasheets/38565.pdf )
Thanks
matjans said:finally finished the casework ...
the top case is just a source selector and volume pot, i still have to build a decent pre.
An externally hosted image should be here but it was not working when we last tested it.
why isn't the image being shown? i did enclose the link in img tags !?
Hi!
Is it a Galaxy box?
What's the temp inside?
yes it is a galaxy case (23x28) and yes,, they're bolted to the sides of the case.
haven't done any temp measurements (i will, gotta get a digital thermometer for that) but the sides stay pretty cool. lukewarm, no more. At normal listening levels, that is. Haven't tried full tilt for an hour or so but that's undoable. And my speakers aren't really that sensitive (89dB).
Heatsink temperature is not so much of a problem. It's harder to get the air-temp inside the case under control. The coil gets pretty hot.
I'll try some bass heavy music next at somewhat louder levels.
Looks like the audiokit galaxy cases are going to be the standard eh?
haven't done any temp measurements (i will, gotta get a digital thermometer for that) but the sides stay pretty cool. lukewarm, no more. At normal listening levels, that is. Haven't tried full tilt for an hour or so but that's undoable. And my speakers aren't really that sensitive (89dB).
Heatsink temperature is not so much of a problem. It's harder to get the air-temp inside the case under control. The coil gets pretty hot.
I'll try some bass heavy music next at somewhat louder levels.
Looks like the audiokit galaxy cases are going to be the standard eh?
Yes, the Galaxy are nice cases, although ordering them from Audiokit is a complete pain... My last ones took about three weeks including the re-order when they arrived all battered and twisted (the muppets sent them in a "large envelope" and as you might expect the shippers bounced all the corners until they were round...)
The price is good, but shipping is quite expensive. They are very good and will talk english to you, but it's clearly a second language, so you must expect a slower response than if you can write Italian.
They have lots of other nice stuff as well though!
Ed W
The price is good, but shipping is quite expensive. They are very good and will talk english to you, but it's clearly a second language, so you must expect a slower response than if you can write Italian.
They have lots of other nice stuff as well though!
Ed W
Ok, can you give me the real internal size for the GX288?
I've a project to build one in the GX248 box (same box but only 40mm height). One box per UcD module.
I've found a supplier for a 2 x 32V 180VA tor transformer with only 37mm height (with fix kit). The price is same of one good 300VA.
Curently all my size simulation seems fine. I'm just afraid of the temp.
If not working, I'll switch to use a GX288 box as you but with a 300VA.
I've a project to build one in the GX248 box (same box but only 40mm height). One box per UcD module.
I've found a supplier for a 2 x 32V 180VA tor transformer with only 37mm height (with fix kit). The price is same of one good 300VA.
Curently all my size simulation seems fine. I'm just afraid of the temp.
If not working, I'll switch to use a GX288 box as you but with a 300VA.
it took my cases about two weeks to get to me. And that wasn't audiokit's fault. The dutch postal service decided to deliver the cases to some other guy called m. janssen on a different address.
if he hadn't sent audiokit an email i still wouldn't have had them.
internal dimensions for the gx248 are 21,0x28,0x4,0
internal dimensions for the gx288 are 21,0x28,0x8,0
if he hadn't sent audiokit an email i still wouldn't have had them.
internal dimensions for the gx248 are 21,0x28,0x4,0
internal dimensions for the gx288 are 21,0x28,0x8,0
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