LEAD ACID BATTERY POWERED JLH CLASS A

[batteryman]

Views please on using 2 pairs of 12v 24AH lead acid batteries (in series) in place of a regulated mains power supply.
The amp I am building is the higher power version of the JLH 10w Class A design (the Tcass dual output transistor updated 1996 design) with +- 24v dc supplies.

However since an amplfier could be regarded as a power supply modulator, the power supply is of equal importance yet often seems to relegated to a secondary (no pun intended) role.
I have heard it said that a LA battery is not noise free, yet I can't believe this noise cannot be filtered out just as it would on a mains supply.

Has anyone compared sound quality of LA or SLA batteries versus a mains supply?
Ian

[geraldfryjr]

If I didn't already have a pair of large transformers this was the route that I was going to take as I have drawn up a class A BTL deisgn that is to run on 24v Down to 2 ohms.
Filtering the noise should not be a probelm as it will probably be mostly high frequency white noise!
The only thing about batterys is that you have to put back into them what you take out in order for them to be fully charged.
Another words if you pull 50 amps in an hour it will take 5 hours to fully charge with a 10 amp charging supply.

jer

[Luke352]

Whats the average ampage that transformers would need to supply in that situation? I think you'll find battaries of that size at least will struggle to give you any kind of decent listening time. Plus you have to remember that at full charge the batteries will comfortably float up over 14v but once loaded and after a short time will be sitting quite lower, will this affect the amp in some way. You'd probably want some decent Deep Cycle battaries, just normal Lead acids will have a short lived life if discharged significantly and than charged constantly. I'd look at getting decent Deep cycles like AGM Deep Cycle Battery, Batteries - Optima Yellow Top the 55ah versions, but that will be quite expensive probably over $1000 by the time you get 4.

[geraldfryjr]

Optima's are a very nice battery but quite costly.
Over here you can get a decent deep cycle type from $70 to $130 each Depending on the current rating and amp/hour range you choose to use.

jer

[batteryman]

Originally Posted by geraldfryjr

If I didn't already have a pair of large transformers this was the route that I was going to take as I have drawn up a class A BTL deisgn that is to run on 24v Down to 2 ohms.
Filtering the noise should not be a probelm as it will probably be mostly high frequency white noise!
The only thing about batterys is that you have to put back into them what you take out in order for them to be fully charged.
Another words if you pull 50 amps in an hour it will take 5 hours to fully charge with a 10 amp charging supply.

jer

You need to put in more than you took out to fully charge a battery so would take about 7hours to recharge yours.

Another advantage of batteries for this sort of intermittent use is being able to recharge & keep fully charged using solar or wind power.

In my case I only need about 8amps total and rarely listen for more than an hour or two so 24ah scooter batteries should be fine.

Ian

[Radugazon]

About noise, there is some infos here in an old thread (post 202)
and infos for alkaline or Ni accus in TNT audio.

is it "noise vs 50 Hz" debate ?

[batteryman]

Originally Posted by Radugazon

is it "noise vs 50 Hz" debate ?

Thanks for the links.

No its not noise V mains hum.

But I prefer the idea of a stiff power supply that does suffer from any mains ripple or other mains borne interference so hence my leaning towards rechargeable battery power.

Then I remembered some discussions about LA batteries generating noise from the electrochemical reaction. But this is surely relevant to electrolytic capcitors as well and I've not seen any criticism of these from a noise standpoint.

No doubt different battery designs (Wet/dry/AGM/Gel) influence the sound but thats an experiement for another time!
I