Line preamps using battery power supply _ any experience ?

[gino1961]

Hi to Everyone
When low noise is a much wanted requirement batteries can help for sure
Do you have any experience of line preamps powered by batteries ? in the high end sector i know of some Jeff Ropwland Design Group units Very very nice but also expensive
I live in a place where the grid voltage is quite dirty The batteries can provide a very nice plus with a complete separation from the grid
Then my fantasy was pumped up by this old paper i found in the web
https://tf.nist.gov/general/pdf/1133.pdf
Impressive indeed
Anyone who has experience of battery powered preamps ?

 

[DVDdoug]

Anyone who has experience of battery powered preamps ?

No, but batteries WILL give you clean power.

I live in a place where the grid voltage is quite dirty

Is that actually causing problems with your audio? Is the noise coming from your preamp?

All audio electronics have filtered power supplies and they should be highly-immune to power-line noise. You are more likely to get ground-loop noise, and balanced connections are the best solution for that.

If you are getting power dropouts, brownouts, or big glitches on your power line, your whole system may need to be battery powered. Or, maybe you can get a good-quality "inverter" (DC to AC converter) and run it from car batteries.

A "real" preamp (phono preamp, or microphone preamp) with high gain will be more sensitive to noise than a preamp that's mostly a control-center with line-level inputs.



...I saw a phono preamp schematic once with dual voltage regulators. The main preamp operated at something like 15V, with that regulated voltage fed into a lower voltage regulator for the phono stage. Since voltage regulators are trying to hold constant voltage they help to filter-out noise.

 

[Blumlein 88]

I've had a MC cartridge head amp that was battery powered. A Sota designed by John Curl. It certainly was quiet. Hum is a notorious problem with MC cartridges because they require so much gain. OTOH, I had a tube based MC cartridge head amp from David Modjeski. You did need to figure out how to get the hum low, but once you did, it seemed just as quiet and performant as the SOTA headamp. With modern op-amps and good design it would be unlikely you'll benefit from battery power.

 

[levimax]

I powered a DIY pre-amp with a DIY +/- 12 volt battery power supply which would completely disconnect from the mains when running on battery and then charge when turned off. It worked perfectly and was dead quiet but so was a good quality linear supply (and I'm sure a good quality switching supply would as well). In the end I didn't see any benefit and it made things more complicated so I don't use it any more.

 

[LTig]

With modern op-amps and good design it would be unlikely you'll benefit from battery power.

This! My Cambridge Duo is dead silent on its MC-input. Any decent line level preamp is dead silent as well. If not it's either broken or a bad design.

 

[gino1961]

No, but batteries WILL give you clean power.
Is that actually causing problems with your audio? Is the noise coming from your preamp?
All audio electronics have filtered power supplies and they should be highly-immune to power-line noise. You are more likely to get ground-loop noise, and balanced connections are the best solution for that.
If you are getting power dropouts, brownouts, or big glitches on your power line, your whole system may need to be battery powered. Or, maybe you can get a good-quality "inverter" (DC to AC converter) and run it from car batteries.
A "real" preamp (phono preamp, or microphone preamp) with high gain will be more sensitive to noise than a preamp that's mostly a control-center with line-level inputs.
...I saw a phono preamp schematic once with dual voltage regulators. The main preamp operated at something like 15V, with that regulated voltage fed into a lower voltage regulator for the phono stage. Since voltage regulators are trying to hold constant voltage they help to filter-out noise.

hi thanks a lot for the very valuable reply As i said i was shocked by the noise graphs in the paper
Some types of batteries added no noise to that of the analyzer
for sure very quiet power supplies can be built using electricity from the grid
and batteries are big heavy and not very convenient
the fact that nobody mess with batteries must mean something The cons outweight the pros

 

[anmpr1]

I never owned a battery powered line level stage, but a couple of battery powered MC step ups (3 to be exact). Those designs were somewhat popular back in the '70s. I think all three were take-offs in one way or another from (the late) Marshall Leach's circuits. I still have one of them in a closet somewhere. They were inexpensive, pretty LN as I recall, but hum prone--you had to situate the box in a certain place for best results. A little movement here or there increased the hum. The location I had best results with was me standing next to the record player holding the box in the air, about three feet above the record player. It worked OK, and sounded fine with Denon cartridges, but after a while my arm got tired of holding it in the air.

Below links to a couple of Leach's designs.

Moving Coil Cartridge Head Amps

Two Head Amps for Moving Coil Cartridges, by W. Marshall Leach, Jr.

leachlegacy.ece.gatech.edu

Actually, very few researchers have seriously studied battery brands and their sonic effects in preamplification circuits. Effects which can make a huge difference in the sound of your music. Those in the know call it 'battery rolling'. Just like tube rolling, only different. And you can do it quickly, almost A/B, without burning your fingers like you would with tubes.

The most well-known researcher cataloging sonic effects of different batteries on sound is probably Josh Scott of JHS. Below links to his important research, along with a demo his recent creation, the JHS Bat-Sim. While not an 'audiophile' product per se, it could probably be easily modded--maybe placed in the tape monitor loop or something, so that audiophiles could partake of its benefits.

 

[MaxwellsEq]

Crimson used to make a popular preamplifier

About Crimson Products Limited

There was the Pink Triangle PIP 2 preamplifier as well.

Reading around the subject, reliability seems to put people off. Also, presumably, internal resistance might play a part over the long-term.

 

[antcollinet]

the fact that nobody mess with batteries must mean something The cons outweight the pros

Or that there are no pros when the equipment is well designed.

 

[gino1961]

I never owned a battery powered line level stage, but a couple of battery powered MC step ups (3 to be exact). Those designs were somewhat popular back in the '70s. I think all three were take-offs in one way or another from (the late) Marshall Leach's circuits. I still have one of them in a closet somewhere. They were inexpensive, pretty LN as I recall, but hum prone--you had to situate the box in a certain place for best results. A little movement here or there increased the hum. The location I had best results with was me standing next to the record player holding the box in the air, about three feet above the record player. It worked OK, and sounded fine with Denon cartridges, but after a while my arm got tired of holding it in the air.

Below links to a couple of Leach's designs.

Moving Coil Cartridge Head Amps

Two Head Amps for Moving Coil Cartridges, by W. Marshall Leach, Jr.

leachlegacy.ece.gatech.edu

Actually, very few researchers have seriously studied battery brands and their sonic effects in preamplification circuits. Effects which can make a huge difference in the sound of your music. Those in the know call it 'battery rolling'. Just like tube rolling, only different. And you can do it quickly, almost A/B, without burning your fingers like you would with tubes.

The most well-known researcher cataloging sonic effects of different batteries on sound is probably Josh Scott of JHS. Below links to his important research, along with a demo his recent creation, the JHS Bat-Sim. While not an 'audiophile' product per se, it could probably be easily modded--maybe placed in the tape monitor loop or something, so that audiophiles could partake of its benefits.

hi thank you very much for your kind and very valuable reply
i have developed a certain interest for battery power supplies because practical issues aside their design is very simple Just a decent cap at the output and its done
moreover i am using presently some very cheap headphone amp battery powered and i have a good feeling
These units are so cheap that is unbelievable Their main weakness are pots quality and connections
The gain could be just fine because many provide the option of gain selection
If i had the instruments i would immediately test them Unfortunately no battery headphone amp has ever been tested on this wonderful site
I have a strong feeling that it could a very nice surprise
I bought one from aliexpress for just 12 euro ! i can see through a small transparent lid that is even made with discrete parts !!!
the others 5 are all opamp based
i am thinking to by pass the internal pot add another decent pot and listen
as i said i am impressed by the lack of noise Maybe the distortion would not be that low but i do not know for sure

 

[Ken Tajalli]

I've had a MC cartridge head amp that was battery powered. A Sota designed by John Curl. It certainly was quiet. Hum is a notorious problem with MC cartridges because they require so much gain. OTOH, I had a tube based MC cartridge head amp from David Modjeski. You did need to figure out how to get the hum low, but once you did, it seemed just as quiet and performant as the SOTA headamp. With modern op-amps and good design it would be unlikely you'll benefit from battery power.

I had one of those!
But frankly, outside MC headamp usage, there isn't much point to batteries. I sent in a 10-year-old DAC with analogue preamp function, Amir measured it (kindly) and the analogue section had a noise distortion figure of -120dB, it was based on 5532 opamps.

 

[gino1961]

Crimson used to make a popular preamplifier

About Crimson Products Limited

There was the Pink Triangle PIP 2 preamplifier as well.
Reading around the subject, reliability seems to put people off.

hi thank you for the very interesting reply For sure phono preamps powered with batteries have been more popular than line preamps
One line preamp i know is the Jeff Rowland Synergy preamp Very beautiful but also very expensive A joy to see and maybe to listen to as well

Also, presumably, internal resistance might play a part over the long-term.

Thanks Maybe this is why in car audio big caps are placed at the output of the batteries ?

 

[gino1961]

I was thinking similar for DAC / preamp. Have a look to see if it helps:
Building a 5V and 12V regulated power supply (using LT3045) with NiMH / Li Ion battery for DAC and 12V PreAmp | diyAudio

hi thanks so much for the link I have to say that if i would use batteries i would not regulate them Just a decent and low esr cap at the output and it is done
I have often heard about batteries noise but i have never seen a nice noise spectrum showing that noise
i am admired by the quality of the tests carried out by Dr Amir that i respect immensely
Unfortunately no battery powered unit has been tested to confirm the noise performances
Yes i think that some dacs could be used with batteries as well But better to check the power consumption
I have one from Cambridge Audio Dacmagic 100 with a 12VDC input that should draw like 0.5A
a battery charge would not last long for sure
Preamps can be done with very little power consumption Like 40-50mA total i.e. ten times less consumption

 

[gino1961]

Sony emphasized the importance of using batteries for their flagship DMP-Z1. There are a few sub-batteries systems in it to separate the noise.
Sony DMP-Z1 portable music player review | What Hi-Fi? (whathifi.com)

thanks a lot again I read from the article

It does have a 10-hour battery capacity when not plugged into the mains

if this unit can be left always on it would be just a matter of disengage the mains when listening
But yes Charge duration is an issue
but for a line preamp i could need just 20mA per channel
That would mean about 100 hours of listening from a 4Ah 12V battery

 

[gino1961]

Not sure how good these batteries-based power supplies are. Some said their noise is less than 1uV.

May be worth to try something similar to see if it works better:

View attachment 366123
LHY Audio LT3042 Low Noise High Precision Linear Regulator 12V2A Dc Power Battery Powered Usb - AliExpress

thank you very much Very nicely built indeed
Speaking of a 12VDC solution i would stay with Sealed Lead Acid batteries
i had a bad experience with a LiIon battery that i pierced by mistake
i have used two in the past to get +/- 12VDC for a simple opamp preamp
they usually draw very little current like 10-20mA what makes them fine for batteries

 

[gino1961]

View attachment 366115
I had one of those!
But frankly, outside MC headamp usage, there isn't much point to batteries. I sent in a 10-year-old DAC with analogue preamp function, Amir measured it (kindly) and the analogue section had a noise distortion figure of -120dB, it was based on 5532 opamps.

hi very interesting Do you have brand and model number maybe ? this sounds very interesting indeed

a noise distortion figure of -120dB

wow

 

[gino1961]

Or that there are no pros when the equipment is well designed.

Hi ! yes you are clearly very right
speaking of practicality, nothing beats a switching power supply and in fact they are everywhere
perhaps a weird solution to isolate the equipment from the mains could be a step-up DC DC converter that takes the 12 VDC from the battery and raises it to the voltage level necessary for the circuit
like it is done in car audio for instance
Unfortunately I don't have the slightest possibility of measuring small noises and I regret it immensely
I'm not saying measure the distortion but at least the noise carpet
When the noise is very low even the self-noise of cheap measuring instruments can be deceiving
Such a shame. I have to find out about the best and cheapest way to measure noise levels of mV
Noise has absolutely nothing to do with music
When the noise is low the listening experience can become exciting. You can hear everything
I am captured

 

[gino1961]

I was thinking about the Sealed Lead Acid batteries too but someone in DIY said it is quite dangerous as it could explore very badly.
Someone on that site mentioned that he saw a really really bad explosion case and he would never put any sealed aead acid batteries indoor.

Wow thank you very much I am sure i have some old ones in my apartment somewhere
I have to check on them immediately
This is a bad issue indeed It could be a show stopper for using SLABs

For me, I believe Sony has done a lot of reasech on the battery types and they finally selected Li Ion may indicate it is a very good choice for our use cases. I was thinking about NiMH but I think Li Ion would be better.

yes you are very right That is a flagship unit I guess they have used the best around
The portable devices i have opened they all use Li Ion batteries of course and they work fine
As i said above their main weakness could be the volume control pot that must be very low in quality considering the overall price
One is not working at all
But they are very quiet indeed I am impressed by a sense of ease in the music
For sure if they can drive an headphone they should be fine with a power amp as well
I cannot perform measurements
I have not seen any test on portable equipment on the site
yet

 

[gino1961]

For the Sony DMP-Z1, I saw some interviews a long time ago, they mentioned that they could make it with A/C power only but they decided to make it to run on battery because of noise consideration as they would like to make the best DAP.

It has different power source modes:

DMP-Z1 | Help Guide | Switching the power source (sony.net)

View attachment 366132
As I was looking at DMP-Z1 recently, their idea prompt me to think about a DIY battery power solution for my DAC / preamp.

Thanks a lot again for the precious information
I am now looking at 18650 battery holder very convenient to put 4 batteries in series ( 4 batteries x 3.7 VDC will provide almost 15VDC good enough for a decent line preamp circuit indeed )
the recharge procedure could be less practical It should mean to remove all batteries from the holder and put them in a charger
It would be nice to have an holder that can switch from parallel to series connection
the chargers operate always with the batteries all in parallel
However it could work
Very interesting

 

[levimax]

One thing you need to keep in mind is that pre-amp circuits are going to use a +/- 12 or +/- 15 volt supply. This is not as straight fotward as you may think. The easiest way is to use 2-12 volt batteries in series and take the power from + from - and from the middle connection. The two issues are batteries are usually not exactly the same voltage and you want the split rails to be identical. The other is the internal resistance of the battery is relatively high. My solution was to use 2- 12 volt batteries in series and a voltage splitter circuit design I found online which used some regulators to split the voltage and some decent size caps to lower the internal resistance. You can use resistors to accomplish this as well but they waste a lot of power. If you are interested I can dig up the link or if the link is dead I have the schematic somewhere.