Has anyone done reasonably thorough comparative testing of different DHT heater supplies? I am interested in Rod Coleman's boards, but wonder how they stack up against various others out there. I could build one myself, but doubt it would be as good as Rod's. I know Guido Tent is marketing one and I have seen one from DIY Hi-Fi Supply. I would like to get the best within reason, but price is important too. Any suggestions would be most welcome.
Thanks,
William.
Thanks,
William.
Don't forget choke input filament supplies!! Or some variation of that like small input caps round 220 - 470uF. I ignored that option because it seemed (and is) a huge undertaking in terms of weight and size. but when I tried it I immediately understood why others recommend it.
My preamp uses filament bias, and that demands a totally clean DC supply. So I actually ended up with a choke input supply feeding Rod Coleman boards.
There are a few such "hybrid" options - Rod uses a gyrator for example.
Andy
My preamp uses filament bias, and that demands a totally clean DC supply. So I actually ended up with a choke input supply feeding Rod Coleman boards.
There are a few such "hybrid" options - Rod uses a gyrator for example.
Andy
Thanks Andy. My feelings about choke input supplies are much like yours were. I would have to have a choke locally made, meaning I would have to provide a design and specifications for it and then hope they are followed properly. My first option is to look at a board; if that can be improved upon by filtering the supply to it, then I will do that too, but afterwards.
Do you know if anyone has done any comparisons between various boards?
Do you know if anyone has done any comparisons between various boards?
I've not compared boards but I have been through a few options. I used LM1084 supplies for a while and I still have one in my amp that needs replacing. There were the basis for the Ronan Reg which had two voltage regs followed by a current reg. They get the job done and are reasonably good. Advantage is the voltage is rock solid and not too sensitive to the input voltage.
Rod's supplies vary a little more with the input voltage but I don't think that matters, and they certainly run cooler which means smaller heatsinks so it's a win situation. They sound audibly better than LM1084 options.
I haven't tried Guido's options - he's done a lot of work on this.
I'm in the UK so Rod is kind of the home team for me, most helpful, and very easy and rewarding to communicate with - which is really useful when you're experimenting with these things. He really is very thorough and has tried out a large range of options to optimise his design.
Andy
Rod's supplies vary a little more with the input voltage but I don't think that matters, and they certainly run cooler which means smaller heatsinks so it's a win situation. They sound audibly better than LM1084 options.
I haven't tried Guido's options - he's done a lot of work on this.
I'm in the UK so Rod is kind of the home team for me, most helpful, and very easy and rewarding to communicate with - which is really useful when you're experimenting with these things. He really is very thorough and has tried out a large range of options to optimise his design.
Andy
I use some big 280mH chokes I got NOS stock - 2.7A so pretty useful. First I used a 10Y with filament bias in my preamp, but eventually preferred the 26 in filament bias. Attached circuit.
I should really use choke input for all 3 stages of my setup - 26, 46 and 300b. One day when I can find space to put all the stuff! You need a rack just for the amp parts, what with HT PSU and filament supplies plus heatsinks etc.
Andy
I should really use choke input for all 3 stages of my setup - 26, 46 and 300b. One day when I can find space to put all the stuff! You need a rack just for the amp parts, what with HT PSU and filament supplies plus heatsinks etc.
Andy
Attachments
nope. you need (big) iron cores. minimum inductance is in the 10mH ballpark and gap from 3A and up for a L-input filter with smallish triodes (300B, 801A etc...).
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