I’ve never heard an oversized transformer sound worse either. I’ve SEEN worse power factor (increased harmonic current on the power line) with oversized transformers. If that results in worse sound, you’re doing something else wrong - like over or under sized filter capacitors or poor wiring.
If you went by sine wave current draw for that amplifier, you would need 2000 VA to handle the load indefinitely (assuming 2-channel) and stay within temperature rise ratings. Even the biggest baddest pro stuff on the market never did that. Typical rule in the olden days was to size down by half, as that would handle playing music as loud and obnoxiously distorted as anyone would ever do (And not overheat on 4 hour gigs). And it would get you within spitting distance of what the bigger one would do in terms of voltage regulation (better results in slightly more continuous power but no more playing music). For home use you could size it down from there. The better stuff would go from 1kVA down one size to 800. Some will cheap out and go as low as 400-500 VA in this application. But going that small you lose enough voltage regulation to notice - and the continuous sine wave tests will bear that out. Even ”pro” equipment is cheaping out like that nowadays. They are all going switchmode and class D anyway, and the cost in terms of performance of undersizing everything there is far worse than doing it with an old school toroid.
The 1500VA Antek would not hurt anything using it, other than your back or the hassle of fitting it in the chassis. The 1000 VA unit will give you close enough to the same sine wave power capacity at 12 pounds lighter and $59 cheaper. You could go smaller but in that application I would use the 1000 VA. 800 is as small as I would ever go for a piece of high quality gear at that power level, and it’s not smaller/cheaper by enough to matter.
If you went by sine wave current draw for that amplifier, you would need 2000 VA to handle the load indefinitely (assuming 2-channel) and stay within temperature rise ratings. Even the biggest baddest pro stuff on the market never did that. Typical rule in the olden days was to size down by half, as that would handle playing music as loud and obnoxiously distorted as anyone would ever do (And not overheat on 4 hour gigs). And it would get you within spitting distance of what the bigger one would do in terms of voltage regulation (better results in slightly more continuous power but no more playing music). For home use you could size it down from there. The better stuff would go from 1kVA down one size to 800. Some will cheap out and go as low as 400-500 VA in this application. But going that small you lose enough voltage regulation to notice - and the continuous sine wave tests will bear that out. Even ”pro” equipment is cheaping out like that nowadays. They are all going switchmode and class D anyway, and the cost in terms of performance of undersizing everything there is far worse than doing it with an old school toroid.
The 1500VA Antek would not hurt anything using it, other than your back or the hassle of fitting it in the chassis. The 1000 VA unit will give you close enough to the same sine wave power capacity at 12 pounds lighter and $59 cheaper. You could go smaller but in that application I would use the 1000 VA. 800 is as small as I would ever go for a piece of high quality gear at that power level, and it’s not smaller/cheaper by enough to matter.
The differences may have been due to stray magnetic fields, capacitive coupling between the primary and secondary windings, or mechanical hum.
Ed
That's what was thinking. I was looking at some other manufacturers and I noticed the higher end guys are going oversize. Like the Mark Levinson ML-9 which is 100w x2@8
Power Supply
Consists of a 1,2 kVA toroidal transformer, a 30A bridge rectifer, and two 36,000 µF capacitors. So I'm going with the 1500va. Now on to what outputs to use. I will be testing the output and thd and imd when finished. This is for home use so it's totally overkill but that's what Diy is all about.
Power Supply
Consists of a 1,2 kVA toroidal transformer, a 30A bridge rectifer, and two 36,000 µF capacitors. So I'm going with the 1500va. Now on to what outputs to use. I will be testing the output and thd and imd when finished. This is for home use so it's totally overkill but that's what Diy is all about.
Outputs? Big as you can. With the 1500 VA trafo you can’t count on voltage dropping like a stone on 2 ohms load (which is actually good) so more SOA is better. I would be using MJL3281/1302 for home use, MJL21193/4 for heavy duty use. 4281 type unnecessary at this voltage, and has some disadvantage in terms of low voltage hFE. If you like the N-suffix package better, bump up the quantity.
I only buy new semis from Mouser or Digikey. Only thing you have to fight there is stock availability (L 21194 not in stock ATM). Looks like half the pair is out now, regardless of which type/package. Big shipment of multiple types coming in April. Id just put in the backorder, and get the one you can now. You could mix L,W, and N package between sides of the complementary pair for a quick test, using only one output and testing at high-ish impedance (8-20 ohms). That could get you a handful of something now. But get them consistent when you fully populate and start running it hard. You end up with a few mismatched spares that way, but I’ll end up using them for drivers in something big. That one doesn‘t need to match the rest of the bank.
Dont buy new semiconductor types or discontinued Jap types (ie 2SC3281) anywhere but regular distribution. They won’t be real anywhere else. I used to buy plenty of generics, older JEDEC types and house numbers from the surplus dealers that used to advertise in the magazines back in the 70’s and 80’s. I was always buy a couple, try, and then order a batch of they were good. I rarely got fakes, even right up to the end. Most of these places have disappeared (the last few during Covid). The ones still around charge a fortune. And the stuff you could get wasn’t suitable for this kind of build anyway.
Dont buy new semiconductor types or discontinued Jap types (ie 2SC3281) anywhere but regular distribution. They won’t be real anywhere else. I used to buy plenty of generics, older JEDEC types and house numbers from the surplus dealers that used to advertise in the magazines back in the 70’s and 80’s. I was always buy a couple, try, and then order a batch of they were good. I rarely got fakes, even right up to the end. Most of these places have disappeared (the last few during Covid). The ones still around charge a fortune. And the stuff you could get wasn’t suitable for this kind of build anyway.