I did the same sort of thing. I also have an extra set if I want to put them underneath. When need arises for babysitter, I can slide a fan under with a low voltage wall wort. Silent, and it has little tiny padded feet that raise it a smidge so air can suck under. I dont need much cooling help, so that works the trick simply.
I used thermal paste. Mine is a SET version and it may be biased just a touch over 1.8A. The Toroidy's also produce a little heat.
I don't have optimal ventilation, but it's not poor either, so take my numbers with a grain of salt.
My comment was mainly that if you are looking at two different chassis sizes, go with the bigger one as xa252 produces some good heat.
I am sure you will love it!
I don't have optimal ventilation, but it's not poor either, so take my numbers with a grain of salt.
My comment was mainly that if you are looking at two different chassis sizes, go with the bigger one as xa252 produces some good heat.
I am sure you will love it!
Overkill. I had the 252SIT on a babysitter... 5U, 400MM, with fully ventilated top and bottom plates ( Ask Gianluca ). The baby sitter ( A dual fan lap top cooler ) dropped the temps about 5C but it wasn't a deal killer.
Now it's has been reborn as a plain 252. I turned it on the other day for a bit, didn't feel so hot. We'll see.
I think the requirement for 500mm is overkill. Just give it air flow ( the ventilated lid and bottom do help ).
998? That is the price of that case in RMB on taobao. I think the type is 4320.
Apart from that, for heat sinks, you want height and baseplate thickness/overall depth over width unless you are mounting 10 or so outputs alongside. With all the heat coming from only two output transistors, a thick baseplate to spread the heat plus height for dissipation matter most. Hence my reluctance to go with dissipantes,for their thin and wide heatsinks.
Since you are in the uk, why not buy a couple of those, quite a few amps have already been built with them. They outdo any of the options mentioned above, but you have to build the case yourself. The eBay seller accepts offers.
Fwiw; I have used 5U 400mm heatsinks from modushop. This in combination with 15mm thick ALU heat spreader, bolted with 20 M5 DIN912 bolts. With bias at 1,7A, you can keep your hand for Max 5
Seconds on the heatsinks. It’s that hot.
If I had the room to use 500mm, I would use the 500mm. Room temperature is 21degr Celsius.
Seconds on the heatsinks. It’s that hot.
If I had the room to use 500mm, I would use the 500mm. Room temperature is 21degr Celsius.
Even in the quietest moments
I wish I knew what I had to do
And even though the sun is shining
Well I feel the rain, here it comes again, dear
And even when you showed me
My heart was out of tune
For there's a shadow of doubt that's not letting me find you too soon
The music that you gave me
The language of my soul
Oh Lord, I want to be with you.
Won't you let me come in from the cold?
I've been using the LP to compare the op amps in the P3... I bought the LP new. Fool's Overture is a great song to exercise the system. And From Now On has the great piano and the vocal harmonies.... A most excellent album. I'm playing right now...
Guess I'll always have to be
Living in a fantasy
It's you for you, and me for me
From now on
Guess I'll always have to be
Living in a fantasy
That's the way it's got to be
From now on
And, recently I had to buy the Crisis What Crisis LP because I couldn't find the original... I mean it's somewhere in there.... Another Man's Woman is a jewel, hidden at the end of the LP...
BTW, your boxes are bigger than my boxes... I need to do something about it. I'm very jealous. My motto is: more boxes, cables, wires, lights, switches, motors....
You know, we're in this hobby because of the music after all....
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I finally played the XA252 base amp, not the SET or SIT.
Oddly enough, like the SIT, is just never seems to be loud enough and it drives you to turn it UP.
I had it on the Maggie 1.7s driving by an Iron Pre Bal via the balanced interconnects, the P3 was driving it, also balanced.
Playing Dream Boat Annie by Heart. You know, you sit down for one song and play the whole thing? Anyhow, it was playing beautiful so I cranked it up. I kept thinking, Damn I want to get to 11!... Anyhow, at one point the right channel didn't sound right, so I turned down the left side ( the Iron Pre Bal has dual pots for L and R ). Sure enough... so I lowered the volume and things came back to normal.
I figured I'd hit the protection circuit....
Well, at least we know the base 252 protection circuit works, the SIT... well... long story.
It does sound pretty good. Both base and SIT have the ability of sounding so clean that they never sound loud enough.
Oh, I was comparing the mosfet 252 with the BA3-bridged F4.... more on that later.
Short term, the XA252 mosfet drives Maggies to 9/10. The XA252 "Macho" SIT won't. Although Mr. Macho has better bass, much more solid.
(Note: my Macho SIT experience is with 90db/w speakers, the Maggies are 83.... ). I have not tried the 252 with the AN... speakers, although I've hooked them up to a pair of Acoustic Energy AE1s, we'll see how that one sounds.
Spoiler- Playing the 45RPM MoFi of Brothers In Arms.... it feels like you can reach out and touch the singer in front of you. Voices over the 252 are amazing.. they have body to them. So does the piano, wonderful sonality.
Oddly enough, like the SIT, is just never seems to be loud enough and it drives you to turn it UP.
I had it on the Maggie 1.7s driving by an Iron Pre Bal via the balanced interconnects, the P3 was driving it, also balanced.
Playing Dream Boat Annie by Heart. You know, you sit down for one song and play the whole thing? Anyhow, it was playing beautiful so I cranked it up. I kept thinking, Damn I want to get to 11!... Anyhow, at one point the right channel didn't sound right, so I turned down the left side ( the Iron Pre Bal has dual pots for L and R ). Sure enough... so I lowered the volume and things came back to normal.
I figured I'd hit the protection circuit....
Well, at least we know the base 252 protection circuit works, the SIT... well... long story.
It does sound pretty good. Both base and SIT have the ability of sounding so clean that they never sound loud enough.
Oh, I was comparing the mosfet 252 with the BA3-bridged F4.... more on that later.
Short term, the XA252 mosfet drives Maggies to 9/10. The XA252 "Macho" SIT won't. Although Mr. Macho has better bass, much more solid.
(Note: my Macho SIT experience is with 90db/w speakers, the Maggies are 83.... ). I have not tried the 252 with the AN... speakers, although I've hooked them up to a pair of Acoustic Energy AE1s, we'll see how that one sounds.
Spoiler- Playing the 45RPM MoFi of Brothers In Arms.... it feels like you can reach out and touch the singer in front of you. Voices over the 252 are amazing.. they have body to them. So does the piano, wonderful sonality.
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"Well, Tony... I think it's a great thing to do, to try to mix together three different amplifiers into a one thing.. I had some experience at mixing oil and vinegar myself... something that living in the Balkans teaches you to do..."
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even he lost count how many times we were bombed by ........ allies
sometime even with his blessing
sometime even with his blessing
I have question about small hum problem and turn on/off small pops. I have 500VA 18AC donut with Aliexpess soft start and LT4320 active rectifiers with 8x10 mF caps and no R between them. One main 2.5A fuse after soft start. I have had a donut horizontally and vertically but still small hum. Could be that the baseplate also affects it? I kind a remember that I did not had that issue before the baseplate. 🙄
Using XA252 SET with not matched FQA mosfets. In the same 5U/500mm case I also have FW F5m installed for comparison testing.
Any thoughts and ideas how to improve it?
Using XA252 SET with not matched FQA mosfets. In the same 5U/500mm case I also have FW F5m installed for comparison testing.
Any thoughts and ideas how to improve it?
Attachments
no pops with regular style of PSU (peasant bridges)
can't comment anything else, nor seeing anything suspicious from pics
now, can you describe that signal wiring , from RCA to pcbs?
regarding pops - in the end, best to implement speaker protection, with delay On and immediate Off
can't comment anything else, nor seeing anything suspicious from pics
now, can you describe that signal wiring , from RCA to pcbs?
regarding pops - in the end, best to implement speaker protection, with delay On and immediate Off
Very difficult to see how psu is wired, but LT4320 active rectification cannot be used with center tapped transformer configuration.
interesting
after initial examination of concept, where I decided set of improvements isn't interesting enough to hassle with, I even didn't got to that detail
can you explain, in few sentences?
If not, just say and I'll dive in datasheet to do my own homework
after initial examination of concept, where I decided set of improvements isn't interesting enough to hassle with, I even didn't got to that detail
can you explain, in few sentences?
If not, just say and I'll dive in datasheet to do my own homework
You will need to be able to tap threads into the heatsink, even if buying from AliExpress. There are obviously no ready made kits for the inverter sinks, the rest of the case can be built with wood/acrylic sheets or whatever you find in the shed.
I believe the reason has to do with AC phase feeding the LT4320 rectifier.
Connected to a center tapped transformer, the positive rail would give expected output, but negative rail will be lower than expected (and wonky) creating non-symetrical bipolar output.
Probably not a good technical answer, but thats what I’ve experienced and read.
Connected to a center tapped transformer, the positive rail would give expected output, but negative rail will be lower than expected (and wonky) creating non-symetrical bipolar output.
Probably not a good technical answer, but thats what I’ve experienced and read.