[icefox]

Hi fellow experts,

Since my return to vinyl my collection of MC pre preamplifier has been incereasing.

All these pre-preamps share a common trait being operated in DC. I read here and there about better performance by operating the unit with battery.

However, I never find a good and easyly achievable solution.

Currently, I have a FM Acoustics 212 and Thorens PPA 990.

If you happen to build something of similar purpose feel free to share your thoughts.

I know basic electronics and can mange stuff in kit form and basic circuit.

iCefoX

[DVV]

Hi fellow experts,

Since my return to vinyl my collection of MC pre preamplifier has been incereasing.

All these pre-preamps share a common trait being operated in DC. I read here and there about better performance by operating the unit with battery.

However, I never find a good and easyly achievable solution.

Currently, I have a FM Acoustics 212 and Thorens PPA 990.

If you happen to build something of similar purpose feel free to share your thoughts.

I know basic electronics and can mange stuff in kit form and basic circuit.

iCefoX

Theoretically, batteries represnt a perfect pool of energy. They are DC by default, and hence no line dirt can ever get past them, period. These days, one can buy even large capacity batteries - Panasonic, for example, manufactures an outstanding range of batteries rated at 12V, 2...5 amps, enough for such a circuit for many, many hours. Especially if you use symmetrical supplies, which implies using two such batteries in plus and minus configuration.

However, practice is a bit different. In my experience, there are two major problems with batteries:

1. charging them. There are literally thousands of circuits freely available to do this, but what is required is a quality automatic circuit, which would cut in after the batteries are no longer used and would charge them slowly rather than fast. This provides for longer charging times, but also better quality charge and increased battery life span, and

2. They tend to sound a little slow and lazy, as if they don't really care to respond to the requirements placed on them. This can be overcome by selecting different types of batteries, but this is a long heueristic process based on the "try it and see" method, which is redious and not too short.

Admittedly, if your circuit is strongly biased into pure class A, this laziness is somewhat reduced as an effect.

Overall, I prefer classic power supplies.

Cheers,
DVV

[icefox]

DVV,

Thank you for your sharing. Do you know of any readily available information on Battery Power Supply kit?

I still want to make one as a DIY project and see how it perform.

Through my reseach alone the line on 47Lab's gear, it looks like there is an offer called PurePower PS. Have you heard about it?

iCefoX

[DVV]

DVV,

Thank you for your sharing. Do you know of any readily available information on Battery Power Supply kit?

Offhand, no, but I will look it up.

I still want to make one as a DIY project and see how it perform.

Of course you do - it's the natural thing to do. It won't cost an arm and a leg, and with a bit o' luck, you might get a really good result. Battery supplies do have their advantages, as I said.

I suppose you understood I wasn't trying to put you off in any way, just pointing out that any technology has its good and bad sides - just as classic power supplies do. There is no perfect technology.

Through my reseach alone the line on 47Lab's gear, it looks like there is an offer called PurePower PS. Have you heard about it?

iCefoX

Frankly, no, I haven't. Which of course means nothing, nobody can have experience with everything. Any particular reason why you ask?

Cheers,
DVV

[8thnerve]

However, I never find a good and easyly achievable solution.

Currently, I have a FM Acoustics 212 and Thorens PPA 990.

If you happen to build something of similar purpose feel free to share your thoughts.

I know basic electronics and can mange stuff in kit form and basic circuit.

iCefoX

I just recently finished the Hagerman Technology Bugle Kit.  It is a fantastic unit that runs off of two 9 volt batteries.  They have a manufacturers forum here.

The kit was very easy to do with plenty of room on the PCB and a very intuitive layout.  And the price is nothing short of glorious.  $25 for the PCB with instructions and a parts list you can get from www.digikey.com for about $26 total!  A great phono pre for $51!!

It's not a Phonomena level pre, but at a tenth of the price, it beats every moderate priced phono section in a preamp that I've heard.  Sounds great with my MMF-5.  And Michael Fremer had very nice things to say about it in a recent Stereophile.

[JoshK]

While we are on the topic of battery power supplies, I have a couple questions.

Teres Audio (which also have a forum here) offer a battery option for their TT motor.   They report great improvement for a nominal optional cost.  This got me to thinking.  Dejan, you said that batter PSs tend to sound slow as if they weren't responding to higher demand but with a TT motor this should be a relatively constant demand, am I wrong?  

Would the transport mechanism of a CD player also require a relatively constant demand?  I know transports don't have a constant rotational speed but I believe they have a constant acceleration.

I am intrigued to know whether powering the transport mechanism of a CD player off a battery would improve the performance of the player but taking a noisy job off the power supply that also does the work for the digital section.

I have many project ideas stirring in my brain if I can ever find time to do them.  I had been thinking about building a top loading transport and powering via a battery PS.  This is totally a brain storm idea at this point but I thought I would ask your guys' thoughts.

[DVV]

While we are on the topic of battery power supplies, I have a couple questions.

Teres Audio (which also have a forum here) offer a battery option for their TT motor.   They report great improvement for a nominal optional cost.  This got me to thinking.  Dejan, you said that batter PSs tend to sound slow as if they weren't responding to higher demand but with a TT motor this should be a relatively constant demand, am I wrong?  ..

No Josh, you are quite right.

Also, please understand, the term "slow" is very relative. They are snail speed compared to Siemens Sikorel caps, which slew at over 10 amps per microsecond, but look at their price. Than add the price of what is required to preceed them.

It becomes even more relative if you actually need say 5 mA from a circuit, and you bias it at say 10 mA. Then the circuit will constantly draw twice the worst case current, so its speed will be defined by the circuit, not the power supply. In such a case, the issue of PSU speed is of no consequence.

Cheers,
DVV

[Dan Banquer]

One of the problems with batteries is that they generally have a high output impedance. There are two ways around this problem.
   1. Use a voltage regulator to lower the output impedance.
   2. Use a large electrolytic cap across the battery.
              d.b.

[DVV]

One of the problems with batteries is that they generally have a high output impedance. There are two ways around this problem.
   1. Use a voltage regulator to lower the output impedance.
   2. Use a large electrolytic cap across the battery.
              d.b.

Dan, if I say "agreed" now, that DOES NOT mean I want another six-pack. You don't have to mortgage the house again.

But seriously, I do agree. Of course, adding either will make the overall circuit larger and more costly still. Typically, for a top notch supply, you will want to add both ...

Cheers,
DVV

[Dan Banquer]

It's a good thing you said that; I'm running out of room in the basement.
                                               

[Gbatokai]

Theoretically, batteries represnt a perfect pool of energy. They are DC by default, and hence no line dirt can ever get past them, period. These days, one can buy even large capacity batteries - Panasonic, for example, manufactures an outstanding range of batteries rated at 12V, 2...5 amps, enough for such a circuit for many, many hours. Especially if you use symmetrical supplies, which implies using two such batteries in plus and minus configuration.

However, practice is a bit different. In my experienc ...

Batteries (I'm assuming we're talking lead acid here) CAN produce small pops and clicks as a result of the chemical reactions that produce the power. I've heard of this being a "problem" in phono stages, although it's easy to solve with an lc-filter. Basically, the power is pure, though.

As for the laziness, this is easy to remedy using reservoir caps of appropriate size. I found this out myself, as I built my first battery power supply (from the bottom up) just a month ago. I built a symmetric supply like you say, and found that bass and macrodynamics where improved when adding a couple of RIFA PEG124 2200uF capacitors for reservoir purposes. The load is approx. 50mA.

[DVV]

Batteries (I'm assuming we're talking lead acid here) CAN produce small pops and clicks as a result of the chemical reactions that produce the power. I've heard of this being a "problem" in phono stages, although it's easy to solve with an lc-filter. Basically, the power is pure, though.

As for the laziness, this is easy to remedy using reservoir caps of appropriate size. I found this out myself, as I built my first battery power supply (from the bottom up) just a month ago. I built a symmetric supply li ...

All well and fine, but just rewind the text - you need a battery charger, batteries, LC filters, capacitors ....

With all that on line, thank you, but I prefer to make a decent classic AC-DC power supply, especially in view of the fact that I have a house full of DeZorel line filters, one of which (Audio Reference Senior) is dedicated to my audio only, the PC uses another PowerStation 1, so there's no crosstalk from the chopper power supply in it (axe swinging hacker power supply is a better term).

Actually, I did experiment with battery power supplies, using lead acid, NiCd, even silver-based batteries. Without the existing base of line filters, they do perform better than your typical, classic AC-DC power supply. One could argue that the line filter adds much to the cost, which is true, but then it also cleans up all the much for the rest of the system, and with three filter stages in parallel, there's still nop crossatlk even after the filter.

All in all, I still much prefer classic AC-DC power supplies, though I freely admit I make them a lot better than you typically see in commercial audio.

Cheers,
DVV

[Gbatokai]

All well and fine, but just rewind the text - you need a battery charger, batteries, LC filters, capacitors ....

Yeah, I'm aware of the cost perspective - a decent battery psu does cost the same as a very decent DIY ac psu. The results with the battery supply have been very good in my opinion, and will be tested by several people against the "stock" preamp sometime soon.

Another thing: For the inexperienced DIY'er - such as myself - it is much easer to build a battery psu than a complete AC psu.

I do own and use line filters; currently one of my own making powers the stereo, while the DeZorel power the computer etc. The reason for this arrangement, is that I'm steadily trying to improve the DIY filter. The Dezorel is good enough as it is, and I bought it partly on your recommendation, Dejan

[DVV]

Yeah, I'm aware of the cost perspective - a decent battery psu does cost the same as a very decent DIY ac psu. The results with the battery supply have been very good in my opinion, and will be tested by several people against the "stock" preamp sometime soon.

Another thing: For the inexperienced DIY'er - such as myself - it is much easer to build a battery psu than a complete AC psu.

I do own and use line filters; currently one of my own making powers the stereo, while the DeZorel power the computer etc. The reason for this arrangement, is that I'm steadily trying to improve the DIY filter. The Dezorel is good enough as it is, and I bought it partly on your recommendation, Dejan

Really? I hope you are pleased with it. You know, for 19 years I have been testing hardware equipment for PCs in the local media, as an editor, author and anchor on my own TV shows, etc, and over that time, my only real fear, my nightmare if you like, has been that of making a mistake. When somebody's stock sells out or stays unsold on my say-so, well, that's a responsability. Sure, it comes with the job, but I still worry about it.

Recommending something here, even if this is a fun forum, is really not any different at all. I'm still influencing, even if only partly, people's decisions to buy and hence their pockets.

So, tell me, are you pleased with it? Do you feel you made the right choice?

Cheers,
DVV

P.S. Actually, I do believe if you worked out the bill of materials for both types of power supplies, I think you'd end up at about the same. Comparing a well made battery supply with a stock AC-DC supply is really no test; the test would be comparing it to an also well made AC-DC supply costing the same +/- 5%. Lastly, batteries are very hard to implement for high voltage, high current supplies; it has been done (e.g. Stax, used to run their 2x100/200/400/800W into 8/4/2/1 ohm loads power amps, with 400 lbs of batteries loaded into a mobile housing), but I would not call that practical, and I'd just HATE to work out the cost of that baby.

[Gbatokai]

I am pleased with it - it is one of the few things I never expect to sell, since there is always use for an extra line filter. It is also good to have as a reference for my own endeavours. Also, the dialog with DeZorel has been enjoyable and interesting - they are very friendly and helpful guys.

As for battery power, I agree with you. The battle stands between two PSUs of the same total cost, and battery power has limited applications dependent of voltage and capacity.

The implementation of battery power is often a sorry sight - MC or car batteries naked on a chair beside the stereo rack, with crocodile clamps providing the connections. I can't imagine that all that ugliness helps the listening experience, apart from being less than optimal electrically.

[icefox]

Batteries (I'm assuming we're talking lead acid here) CAN produce small pops and clicks as a result of the chemical reactions that produce the power. I've heard of this being a "problem" in phono stages, although it's easy to solve with an lc-filter. Basically, the power is pure, though.

As for the laziness, this is easy to remedy using reservoir caps of appropriate size. I found this out myself, as I built my first battery power supply (from the bottom up) just a month ago. I built a symmetric supply li ...

[DVV]

I am pleased with it - it is one of the few things I never expect to sell, since there is always use for an extra line filter. It is also good to have as a reference for my own endeavours. Also, the dialog with DeZorel has been enjoyable and interesting - they are very friendly and helpful guys. ...

That's a load off my chest, I seriously mean that. Maybe I worry too much, but I can't help it. Sure, I do my best to make it any assessment a fair one, but I'd be a fool to say mistakes cannot happen despite everything.

Anyway, the point is you're satisfied with it.

As for the DeZorel people, I agree, they are nice guys trying to do their job as best they can. I'm not saying they are perfect, I faulted them a few times, but to their credit, they did something about it. And they still are, that's what I like about them, they never sleep, they are always looking for ways to improve their products.

Cheers,
DVV

[icefox]

http://sound.westhost.com/project98.htm

Guys, have a quick scan through of above articles, seems to have a lot of good info.

Unfortunately, I am not technical enough to make the best use of it. I hope some chaps like DVV and Gbatokai can make a better sense out of it.

Gbatokai, do you think it can give some sort of improvement to your current project?

[Gbatokai]

Yep, it would be the next improvement, since I must now manually switch between charging and operation.

Have you had any success decoding the hurried description I sent you?

[DVV]

http://sound.westhost.com/project98.htm

Guys, have a quick scan through of above articles, seems to have a lot of good info.

Unfortunately, I am not technical enough to make the best use of it. I hope some chaps like DVV and Gbatokai can make a better sense out of it.

Gbatokai, do you think it can give some sort of improvement to your current project?

Looks like a nice project, the link to Rod Elliot you sent, Icefox. Very straightforward, no bull, just the essence. Good design principle, I'd say. Also, easily available parts, at least here in Europe.

Just one thing about it I don't understand - he used a BD139 (80V, 10W, 2 A, Hfe > 60, Ft > 60 MHz), which is at the bottom of the medium power transistor list, although it's an outstanding device (heck, I'd cut my veins if it didn't exist). Why not use another, just as good in most respects, but far more powerful, like Motorola's MJE 15030? Not implying greater currents, just offloading the poor thing which has to swing all of the voltage and all of the current?

Cheers,
DVV