Battery powered tube preamplifiers?

treitz3

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Dec 25, 2011
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The tube lair in beautiful Rock Hill, SC
Good afternoon, gentlemen of the forum. I have come to a point in my audio journey where I am having some serious self-debate with regards to the pre-amplification of my rig. I currently have and have had for years a custom made Dodd MLP tubed pre-amplifier. I consider myself lucky because it is one of only 42 ever made and the only one of it's kind with a wood faceplate with matching wood remote [both of which were not offered with this model] as well as it being the only known Dodd MLP preamp to have wooden input selector and volume knobs, on a now discontinued model. Gary prides himself on being a minimalist with regards to his designs and the remote is no exception. There is only an up and down button for the volume control but for my needs, it's perfect.

It has a separate power supply with a 5' umbilical cord to keep the two apart from each other. Being a 12Ax7 based unit, it utilizes 4 12AX7 tubes producing a real quiet background and respectful, clean frequency response by any audiophile standard. The tubes I have found that pair well with the Dodd MLP are the Ei 12AX7 Ei Gold pins. It has an HT bypass as well as 3 inputs, 2 outputs and a mute switch.

The build quality is quite impressive with nice attention to detail, cleanliness and layout. The tubes are easily rolled and you don't have to remove any boards or go through your elbow to get to your rear end to get too them. 10 Allen screws, lift the top and you are in like Flynn. It is apparent once you see the Dodd MLP that quality products were used. From the power supply all of the way up to the inputs of the pre, to the laser imprints on the wood faceplate.

When I first saw it, I referred to it as the "Fred Flinstone" pre-amplifier. It looked like something that one might find in his stone hut. Of course once I heard it? I listened for hours on end with the system it was on. We played around with different combinations of gear, PC's, IC's SS CDP's and tubed CDP's and even different speakers. The Dodd MLP performed so well, I knew right then and there that one day, I would own one.

Long story short, life happened and a couple of years go by and a good friend of mine asked me if I wanted to borrow a pre-amplifier when I had a bout with Mother Nature and she not so kindly offered me a lightning strike at my house, which fried certain components within the rig. I asked him which pre he was talking about and I couldn't really think as to which one he was talking about. When I asked that he describe it to me, the more I heard, the more I realized that he was talking about this "Fred Flinstone" pre I had heard years before.

Long story short, I ended up purchasing the unit and it turns out that it was the very same unit I had heard at an audio event years before. Well, I had heard it once before and it commanded my attention. When I first put it into my rig, the sound commanded my attention once again. There were just so many things that were now apparently obvious that I used to have to strain to hear....along with all of the new sounds that were always there, just masked. This pre has been in my rig ever since. The only thing that has changed is the tubes and like I have mentioned before, I have settled on the Ei 12AX7 Gold pins.

Why is it discontinued, you ask? Well, Gary has apparently outdone himself and built an even better pre-amplifier. The reviews are glowing and Gary flat out told me that he discontinued the other pre lineups because this one sounded so much better. The new pre he has is a tubed preamp but this time, it is battery powered.

Now, I am a little skeptical because I absolutely love the Dodd MLP and what it does for the end result as to what hits my ears. What I was wondering is if anybody here has any experience with battery powered pre-amplifiers and what observations they may have on them.

Might this be something that you would recommend [a battery powered pre]? What may be the pro's or con's to having a battery powered tube preamp? Any insight or observations that you may have had or have now would be greatly appreciated.
 
Hai ive owned the nagra plp for 3 years .
The battery operation gives a kind of slick smoothnes to the sound , my impression .
I wouldnt think of miracles happening from batterypower , i heard the pll on many occasions , and that might have sounded better , i suspect one could get loss of dynamics using battery power at least in that design.
secondly the bass is now much better , i dont know if that has to do with the battery , or the different build up /circuit

Oeps i once dropped that lightweight powersupply unit on the floor , that costed me money.
 
My first battery powered preamplifier was a modified Meridian 101 or similar (I am not sure anymore) using 4 x 2Ah 12V lead acid batteries . At that time I was very deceived as it did not sound better than the standard battery, but the batteries were useful to power a small hobby drill ...

More recently, I spent some time with a full Nagra system (PLL, CDC and the 845 based VPA monoblocks). I could get it at a very nice price because it was taken by a dealer in part exchange and it did not power, as it needed 8 D NiCad cells, that I could get easily in a battery shop. :rolleyes:

The tubed PLP was not directly powered by the batteries - they powered an internal DC-DC converter. I could never understand why the preamplifier was battery powered and the CDC used only a mains power supply - the big advantage of having a full floating system was lost this way.

The Dartzeel preamplifier also operates in 4 Lead acid batteries - and I can tell it sounds better when used only on batteries.

Some modern power regenerators, such as PurePower can operate on batteries - soon I intend to try one of them. Two friends who own Dartzeel amplifiers swear it is was a big improvement in their systems, but I did not listen to it yet.
 
Don't forget the Veloce.

Also battery technology is changing allowing things to be done that weren't possible a couple of years ago. Years ago, my biggest complaint will battery powered units was a loss of dynamics. Clean but boring :(
 
There's also the Dynaudio Arbiter preamplifier. I would consider it among the best preamplifiers ever built.
 
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I did try also having it on juice for a day , and then switching to battery power as well as removing the AC powercord completely .
It did play for a certain amount of time , but it seemed like the life got sucked out of the presentation .
kind of the same feeling i have about powerconditioners , i heard them at dealers and i didnt like it , a compressed /smooth operation.

I havent heard the dartzeel yet , shame on me
 
One thing folk may fail to realize is that batteries are by no means a perfect source. No power-supply hum, true (assuming a linear regulator), but they tend to have variable output voltage and impedance. The former may require a good regulator circuit, and the latter storage caps to provide charge storage for transients. If a switching supply is used to generate higher voltages then it will have all the same issues of any such supply.
 
One thing folk may fail to realize is that batteries are by no means a perfect source. No power-supply hum, true (assuming a linear regulator), but they tend to have variable output voltage and impedance. The former may require a good regulator circuit, and the latter storage caps to provide charge storage for transients. If a switching supply is used to generate higher voltages then it will have all the same issues of any such supply.

French designer Jean Hiraga designed some audio equipment powered by batteries in the late 70s and as far as I remember he used huge capacitors (up to 1 Farad ) to decouple the batteries and provide charge storage for transients, as you say.

The good thing is that they are a floating noiseless DC supply - I remember reading something as low as 10 nV at low frequencies.
 

Edwin's been working on this unit forever :) I thought it got a review in SP a while back? Or then somewhere. Maybe HiFI+? I think that it's probably available in Europe but the US Siltech distributor doesn't bring it in. Edwin also showed a speaker at CES three or four years ago that had a lot of promise but it never has seen the light of day. I had tried many years ago to get a a unit for review but it never panned out.
 
Don't forget the Veloce.

Also battery technology is changing allowing things to be done that weren't possible a couple of years ago. Years ago, my biggest complaint will battery powered units was a loss of dynamics. Clean but boring :(

This was my experience as well. I had the Rowland Coherence II for a couple of years and once I replaced it with the Boulder 1010 the whole system came to life.
 
Just to add to Don's comments, the downsides of the two types of supplies can be characterised also as:

Mains supply: very poor quality AC, as a sine wave it's a disaster; very high levels of very nasty noise superimposed. A good power supply has to block all the unpleasant stuff, and generate decent DC from the poor quality, very non-ideal AC signal.

Battery supply: already DC, no unpleasant noise and transient rubbish present, but as a DC supply, pretty terrible, will sag dramatically at the slightest provocation. So a good power supply has again to do quite a bit of work to generate high quality, constant voltage under all conditions, levels.

Frank
 

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