Yup. Pick a temperature or a wallet slice to pick the temperature... My Triad runs over 80°C (250VA for idle of 320V @ 240mA and large PS caps, 12GT5) and it's run 24/7 for almost a year so far.... My Hammond runs 95°C though (454VA for idle of 560V@400mA, small PS caps, KT88) so who cares how hot it gets it it's within spec?
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My "Pass de-lite" mod that uses a tube front end to drive a source follower loaded with 300W light bulbs (22R or so I think) runs at ~100°C.
My 6P45S amp which is the same as the 12GT5 except for current, is running on a 625VA Hammond (1182P117), 320V @ 400mA. It's about 60°C but it costs more.
My designs want peak currents because the power section runs from a Delon doubler, and the front end runs from a quadrupler. Almost 6000µF in one of them, too... That's why I spec a 250VA part for a 30W stereo amp.
My 6P45S amp which is the same as the 12GT5 except for current, is running on a 625VA Hammond (1182P117), 320V @ 400mA. It's about 60°C but it costs more.
My designs want peak currents because the power section runs from a Delon doubler, and the front end runs from a quadrupler. Almost 6000µF in one of them, too... That's why I spec a 250VA part for a 30W stereo amp.
FWIW I hate running transformers very hot, 80C and even worse 95C are VERY hot, and 100C is crazy, you can melt or at least soften and deform a plastic bobbin and definitely toast a cellulose based insulator sheet.
If anything because copper is PTC and the needless high temperature makes resistive losses even worse.
In my fan cooled amps, part of the air flow goes through and around power transformer, go figure.
I find it important to dedicate forced cooling for it, that´s how much I care.
If anything because copper is PTC and the needless high temperature makes resistive losses even worse.
In my fan cooled amps, part of the air flow goes through and around power transformer, go figure.
I find it important to dedicate forced cooling for it, that´s how much I care.
Personally, I have a zero fan in audio equipment policy. Also the 100°C number I quoted is the heat sink temperature - it's a class A SE amp. Transformer should be slightly cooler. Toroidal transformers don't have a plastic bobbin to worry about, either 🙂
I'm running it that hot to stress test it. So far the only failure I've had was a 12V SMPS that worked fine until it cooled down to room temp, then it wouldn't turn on anymore. IIRC it needed new caps.
I'm running it that hot to stress test it. So far the only failure I've had was a 12V SMPS that worked fine until it cooled down to room temp, then it wouldn't turn on anymore. IIRC it needed new caps.
Interesting link, I try that power Transformer work under 60ºC more comfortable for all.
seem that toroidal transformer are better for low voltage big current as filament supply and SS amp.
Now my war is with mechanical noise, where resin-varnish, tension of the wire, diameter of the wire and dielectric material are very important.
this mechanical noise travel around all, where at the end the good or worse depend not only about the timbre, punch etc, noise is important too.
a good power transformer for me is when work under 35db at 60ºC ( 20ºC room )
seem that toroidal transformer are better for low voltage big current as filament supply and SS amp.
Now my war is with mechanical noise, where resin-varnish, tension of the wire, diameter of the wire and dielectric material are very important.
this mechanical noise travel around all, where at the end the good or worse depend not only about the timbre, punch etc, noise is important too.
a good power transformer for me is when work under 35db at 60ºC ( 20ºC room )
A good transformer should not make any noticeable sound 🙂
My Hammond sounds like a pad transformer but I can only hear my toroids when power is first applied (like a Degauss in a CRT monitor kind of).
My Hammond sounds like a pad transformer but I can only hear my toroids when power is first applied (like a Degauss in a CRT monitor kind of).
Noisy transformer can't be good by default.
That usually means bad assembly or load capacity out of spec.
That usually means bad assembly or load capacity out of spec.
all power transformer generating noise, to test put the mic in contact with the core, a bad transformer when wires are not to tense or not good varnish give over >45db at is possible to listen at 3m in silent room, when transformer work under 35db is not possible to listen. but there are many PSU Trans. for me the problem is 950v line with 10 layer of small wire, now I order with teflon between them and two bath with varnish.
My mics are dynamic so I'll I'd hear is the magnetic field, not the mechanical noise. 🙂
Ever just potted it instead?
Ever just potted it instead?
Don't need a stethoscope... A screw driver is good enough for that. 🙂
In the auto shop we do this:
In the auto shop we do this:
I’m 30 years into it all, not a pro, not an EE, just years of building and listening… there is no denying you are listening to your power supply.
You can build an excellent power supply with any type/format of transformer, just pay attention to the resulting limits. You want to avoid “good enough”. You want excellence.
It’s worth building one very good power supply and use it on multiple builds via umbilical, or better yet multiple power supplies 🙂 If each tube has its own “meal” it’s going to perform to its maximum potential. Its a lot of fuss, weight and space but, it leads to excellent results. Give in early and have more fun!
EEs and their type will argue all day about theory and different ears each with different abilities and training will argue endlessly. You will get agreement on one thing if you dig intelligently, you are listening to your power supply, make it the best you can!
Oh, for the record, Antek makes very good transformers for cheap, just stay well inside their ratings. I also use a lot of Hammond, Edcore and Lundahl… just stay way inside of their ratings 🥰 and remember you get what you pay for.
You can build an excellent power supply with any type/format of transformer, just pay attention to the resulting limits. You want to avoid “good enough”. You want excellence.
It’s worth building one very good power supply and use it on multiple builds via umbilical, or better yet multiple power supplies 🙂 If each tube has its own “meal” it’s going to perform to its maximum potential. Its a lot of fuss, weight and space but, it leads to excellent results. Give in early and have more fun!
EEs and their type will argue all day about theory and different ears each with different abilities and training will argue endlessly. You will get agreement on one thing if you dig intelligently, you are listening to your power supply, make it the best you can!
Oh, for the record, Antek makes very good transformers for cheap, just stay well inside their ratings. I also use a lot of Hammond, Edcore and Lundahl… just stay way inside of their ratings 🥰 and remember you get what you pay for.
Any preference or guidance between the two? Mechanical noise or DC line issues with the Antek? The target project is a small amp bench testing with a Hammond 270HX rated at 550V CT @ 200 ma. Powering one amp channel at 60 ma gets the Hammond too hot for a 5 second touch test while buzzing audibly. Based on previous experience I don't trust it not to go up in smoke with two channels. Thanks.
On the contrary, not much stuff to argue between Engineers (of any kind) because they are talking about measurements, "numbers".
Say, any doubt about a transformer temperature? 85C? ... 95C? ... just stick a thermometer there and read the display or scale.
No arguments possible after that.
While the NON Scientific ones (those who despise or plain ignore Physics and Math) can argue for Centuries on subjective opinion.
Great to know, thanks. Doesn't hurt that even with the optional cover they're the least expensive.
(Kyuss fan?)
Imagine a guy sitting at the window of a roadside diner , enjoying his coffee and casually watching the traffic flow by on the highway.
Something red in the periphery of his vision makes him focus on a yup, you guessed it, a Ferrari , looking so . . . . . Ferrari.
As he's taking in the driver's blonde hair and wishing he had some binoculars handy, behind the Ferrari in the left lane a Burgman motor scooter slides by a good bit faster than the (by now in his imagination) gorgeous blond babe .
Now, not being into technical stuff that much he's satisfied with the data he's just collected and after finishing his coffee walks away thinking, "Huh, Motor scooters are faster than Ferraris. I never knew. Amazing!"