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Old 8th June 2006, 01:15 PM   #1
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Default filament supply: batteries v TentLabs?

Hi

I was looking a really good preamp, and have chosen to build one of the three Jim de Kort designs using the 26 tube at www.vt52.com/diy/myprojects/projects.html (I would be using it in either a 100 dB efficient system or 115 dB horns).

Two of the three of Jim's designs , to overcome the propensity to hum of the 26, use a battery filament supply.

Iím not opposed to batteries, but the other really good option is the TentLabs Directly Heated Tubes Supply http://www.tentlabs.com/ProductEntit...terSupply.html Probably a little more expensive and a little more convenient.

My #1 criteria is sound quality. Has anyone tried both or have a comment about which should sound better?

Thanks!
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Old 8th June 2006, 01:35 PM   #2
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Bas

What do you think?

Cheers
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Old 8th June 2006, 01:57 PM   #3
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My speakers are about 87db efficient and I can run my DHTs in the preamp off bench DC power supplies. I didn't hear any special improvement with batteries. the convenience of DC supplies certainly beats the fuss of recharging batteries. Battery supplies have always been - for me - a kind of "good idea at the time" that I've abandoned through sheer aggravation. There is a rather cool circuit about which automatically switches between two banks of batteries - Gary Pimm or somebody like that. At least that would be a "build it and forget it" option.
I think all this depends on the efficiency of your speakers. Below 90db and you're probably fine with DC supplies. Over 100db and you may well be looking at batteries. I'm looking at common mode chokes in the DC supply as well as voltage regs. Haven't built the supply yet. there's also the RonanReg circuit which is no doubt about on the Net, though John Leverault has run out of boards. Andy
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Old 8th June 2006, 02:19 PM   #4
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You think neither the TentLabs or the RonanReg would be ok over 100 dB?

Cheers
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Old 8th June 2006, 02:43 PM   #5
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Quote:
Bas

What do you think?
I'm not qualified to give an educated opinion. I will say this. DHTRob tried one of the Tentlabs for a preamplifier. Remember the Tentlabs were initially made with your typical output tube say a 300B in mind. Rob found they were quite noisy (for a preamp DHT). Guido agreed and declared his intent to improve the tentlabs supply for preamp dht duty, I don't know if he has done that yet. An email to tentlabs can clarify that.

I find the Tentlabs expensive (but that is a fact of life if dealerships are involved) that is the only drawback. Batteries are cumbersome.

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Old 8th June 2006, 02:46 PM   #6
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You think neither the TentLabs or the RonanReg would be ok over 100 dB?>>

I don't know the answer to that - I've only tried various filament supplies with my 87db speakers, where DC supplies are fine. I know from reading posts that noise becomes a big issue with high efficiency horns, but you'd have to ask people that use them. Andy
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Old 8th June 2006, 02:48 PM   #7
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Why not build your own?
pdf
http://home.quicknet.nl/qn/prive/sus...mentSupply.pdf

or if you don't have pdf check out the attached jpg.

This is one Kees Soeters built for his 27 driver tube.

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File Type: jpg keessoetervccs.jpg (41.4 KB, 1338 views)
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Old 8th June 2006, 03:10 PM   #8
EC8010 is offline EC8010  United Kingdom
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Why do you need a pre-amplifier? Are your power amplifiers such low gain that you need to amplify the signal from CD?
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Old 8th June 2006, 10:16 PM   #9
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Bas

How well would Kees work for preamp dht duty?

EC8010

Good question, buy a friend put an Ultrapath pre in a passive pre system, and both of us preferred detail and imaging . . (other ears liked it less, but I usually listen through mine

Cheers
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Old 9th June 2006, 12:39 AM   #10
Rocky is offline Rocky  Norway
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Quote:
Originally posted by Bas Horneman

Batteries are cumbersome.


You got that right, but in some cases still less cumbersome than trying to put together something that'll work as good. I've never tried Guido's supply modules so I can't speak for them. I ended up with batteries because I'm too lazy to investigate other options - and once chargers and relay control unit is built it's really not that much hustle at least not with my tubes - but they don't draw an amp like the '26 either..

For my 5V/250mA filaments I use 12V batteries and current regulators. Works like a charm.
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