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I unboxed my DRD 45 kit this evening. I was completely awed by the size of these power trannies. What gives? These are 1.5W amps! They weigh nearly 10lb. Does this mean that my 845 monoblocks, to be to scale to output power, ought to weigh 150lb?! Now, I'm sure that's not the case, as the transformer is going to have some base "constant" in its weight... but to be to scale, just how big would the power tranny of an 845 amp of 30W output need to be?This got me thinking about power supplies and realizing just how little I know (no surprise, I'm not a designer nor EE). What is "enough" for a class A amp? What ensures that the power supply voltage will never sag and have completely adequate dynamics? Is this a good discussion to have here or is it too basic?
Follow Ups:
Ummm, well, in a manner of speaking - probably.So far I have been reluctant to weigh my Dowdy designed GM70/75TH amps _grin_
At a recent bottlehead listening session, somebody said "what amps do you want to listen to next?"
Dowdy said "the amps with the most pounds per watt"
It takes a lot of iron to squeeze out the retrieval of low level detail.
I'm not familiar with Dowdy. What do these things weigh?The deHav GM70 amps sound killer and lb/W is, well, pretty low. Lower than my Consonance 845 monos and most other 845 monoblocks.
I know this isn't something as simple as "the more it weighs the better it sounds", but this is interesting. Well, for me. For most here it's probably rather basic.
Jim Dowdy is a custom amp builder. He was christened the DowdyLama by Harvey Rosenberg and posts here under that user name.It is not just as simple as lbs per watt. However, all other things being the same, lbs per watt will probably win.
I honestly don’t know how much my 75th/GM70 amp weighs. Hell, both filament supplies alone probably outweigh many production amps. Then there’s a mercury vapor rectified power supply that’s big and heaver than the filament supplies, then signal chassis for each channel. There are five chassis'
Regards
will use the biggest iron I have ever seen...except perhaps Orey. But that is audio on the far outer fringes of reality.Ed knows the story there...:)
Did he use surplus or those Italian monsters? Low DCR comes with a [size] price, you know. Josh's stuff weighs in pretty high too. He uses amorphous c-core iron which weighs less than the big EI stuff, but it still adds up when you build amp of this quality.
At any rate, the lineup of 75TH/GM-70 is about as good as audio gets. All tungsten filaments, all DHT...NO cathode followers to spoil the sound....just good clean fun.
And that copper glow....mmmmmmmmmmm.
I'm thinking he got the output transformers from you _grin_Got a toriod out of maryland for the power supply.
I think surplus sales for the filament supplies.
You're right about the combination - certainly the best I've ever heard _grin_
we want to see those beasts. ;-)sounds like tube-rectified filament supplied maybe?
Dowdy rules.
75th/GM70 all chassis' weigh 263 lbs.I'll try to take a pic of it with everything lit up.
While we're listening to them now - I built the boxes out of plywood, and have plans to wrap them with something in a more attractive finish.
So, what I'm saying is - they're not pretty at this point _sad grin_
They sure do souund great - Got the system coming together now, pretty good.
There is a lot of glow coming from the GM70's, and 75th's - then the soft blue glow of the four 872's in the power supply beneath.
Sounds like a great setup! damn, lots o weight. Pics would be great. I hear what you mean re: building chassis - that takes the most time when it comes to making a nice DIY amp. The lightshow is almost as good as the music on an amp like these. I use 75TH's too, a great tube.
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