I'm my endless quest to find a suitable xformer for my GC mono blocks locally, I suddenly realised that using batteries would be actualy cheaper and better.
Why not? sealed lead/acid 24v, 2 per GC (or 2 for the 2, w'ell see)
(like 15$ each....)
and a simple circuit to charge them (and you know how simple they can be).
with current peak up to 500 amps, I guess they will beat any standart power supply. Shine! Bright yellow, little 1 inch thick rod.
(taken from a personal experience with some batteries when I was young)
So, anyone has any comments or things to say that I could take into consideration?
Why not? sealed lead/acid 24v, 2 per GC (or 2 for the 2, w'ell see)
(like 15$ each....)
and a simple circuit to charge them (and you know how simple they can be).
with current peak up to 500 amps, I guess they will beat any standart power supply. Shine! Bright yellow, little 1 inch thick rod.
(taken from a personal experience with some batteries when I was young)
So, anyone has any comments or things to say that I could take into consideration?
for LM3875 +/- 24V sounds considerably better that +/- 12V
to get nice earthing you need separate battery supplies for each amp.
some kind of quality electrolytic bypass cap improves the sound. I have not experimented to find optimum but I would guess 47uF - 470uF would be a good starting point.
don't forget to use fuses on the battery terminals !
mike
to get nice earthing you need separate battery supplies for each amp.
some kind of quality electrolytic bypass cap improves the sound. I have not experimented to find optimum but I would guess 47uF - 470uF would be a good starting point.
don't forget to use fuses on the battery terminals !
mike
I tried +/- 24 v on the rails and to be honest i really couldnt hear any difference.I also tried larger caps on the rails to ground, found that the lowest value (that could do the job) was better,also the 6.8 uf caps sounded like it gave a better HF response.The caps on the rails are there to keep out any AC hum (and provide current on instant demand) and with battery P/S this is not a problem.The cap between the power pins is there to keep out HF hum and as stated i found out (trial and error, and lots of error LOL) that the lowest that you can get away with ,the better.
I am using fostex fe-103e horns and as i am in a small apt i really dont need the greater power of the +/- 24v P/S.I am also using 250K feedback resistors as the gain is more than adequate and i hardly ever go beyond 10 o clock using 10k/50k pot shunted to ground.I am also using a 500k multi turn pot from pin 7 to ground and after letting the amp warm up for 2 hrs i just dial in 0 offset.
ron
I am using fostex fe-103e horns and as i am in a small apt i really dont need the greater power of the +/- 24v P/S.I am also using 250K feedback resistors as the gain is more than adequate and i hardly ever go beyond 10 o clock using 10k/50k pot shunted to ground.I am also using a 500k multi turn pot from pin 7 to ground and after letting the amp warm up for 2 hrs i just dial in 0 offset.
ron
I have to confess that I went straight from the 1uF that thorsten suggested to DNM 10,000uf T network slit foil caps.
the T networks were clearly better than the 1uf so I left it there.
I guess the ideal supply voltage depends on the speaker sensitivity at the time I was using 89db/w/m and +/- 24V helped.
cheers
mike
the T networks were clearly better than the 1uf so I left it there.
I guess the ideal supply voltage depends on the speaker sensitivity at the time I was using 89db/w/m and +/- 24V helped.
cheers
mike
To me batteries sound much better too even compared to a maximised gc power supply.I can tell easily because in my set up I can switch between the two almost on the fly.It reminds one more of the advantages of good SET or tube amps without the disadvantages.There is more depth and liquidity while the hard to describe word "musicality" pops in your mind.All this and excellent speed and dynamics in the bass as well.
The AC ps while not bad at all sounds a bit dry and constricted in direct comparison.
I would also vote for 24V , at least on my OPA 549 chip it sounds more dynamic.With 12v everything sounded a tad slow and it will only work with very efficient speakers needing only a few watts but it is easy to experiment with this and find the best solution for you. Don't forget batteries in numbers can get expensive.A dual mono 24v set with 8 batteries will cost much more than a simple AC gainclone.
The AC ps while not bad at all sounds a bit dry and constricted in direct comparison.
I would also vote for 24V , at least on my OPA 549 chip it sounds more dynamic.With 12v everything sounded a tad slow and it will only work with very efficient speakers needing only a few watts but it is easy to experiment with this and find the best solution for you. Don't forget batteries in numbers can get expensive.A dual mono 24v set with 8 batteries will cost much more than a simple AC gainclone.
I did get an AC supply to sound pretty much the same as batteries but it consisted of
0.1cap/transformer/4.7cap/bridge/2200cap/choke/4700cap/choke/10000cap
( this was for a balanced working amp so I did not have +/- rails and thus halved the number of caps used )
so the cost is about the same or more that 8 batteries & 2 chargers ( the chargers where just transformer & bridge )
so perhaps batteries pro rata are cheaper !
mike
0.1cap/transformer/4.7cap/bridge/2200cap/choke/4700cap/choke/10000cap
( this was for a balanced working amp so I did not have +/- rails and thus halved the number of caps used )
so the cost is about the same or more that 8 batteries & 2 chargers ( the chargers where just transformer & bridge )
so perhaps batteries pro rata are cheaper !
mike
Your asking the question has highlighted in my mind that I used very nice caps, DNM slit foil, throughout and the most make shift chokes as is possible - the secondaries of multicomp El 20VA 4.5V + 4.5V transformer from Farnell.
The increasing cap values towards the amp tends to reduce ringing or overshoot on turn-on.
this pic shows the stuff from the diodes onwards but the 4.7uf after the transformer really smooths out the sound.
K1 + K2 are inductive coupling
The increasing cap values towards the amp tends to reduce ringing or overshoot on turn-on.
this pic shows the stuff from the diodes onwards but the 4.7uf after the transformer really smooths out the sound.
K1 + K2 are inductive coupling
Attachments
How much playing time do you get w/ batteries?
After reading this thread I started looking up batteries and chargers and was wondering how you figure out which AH rating is needed(assuming 24V +/- rails)?
I've found some reasonably priced 12V sealed lead/acid batteries and there are plenty of 3-mode chargers for cheap. Hook them up in series and we're cooking (or not).
The question is how powerful of batteries do you need for reasonable playing time with fairly efficient speakers (97dB/8ohm & 90dB/4 ohm) at a decent level?
Is this a stupid question?
After reading this thread I started looking up batteries and chargers and was wondering how you figure out which AH rating is needed(assuming 24V +/- rails)?
I've found some reasonably priced 12V sealed lead/acid batteries and there are plenty of 3-mode chargers for cheap. Hook them up in series and we're cooking (or not).
The question is how powerful of batteries do you need for reasonable playing time with fairly efficient speakers (97dB/8ohm & 90dB/4 ohm) at a decent level?
Is this a stupid question?
7 amp/hr offer good value for money , I think this is because they are a made & used in high numbers.
this size offers reasonably low internal resistance
I have found that they last for several days normal usage.
you can work it all out by dividing the average current consumption into the into the amp/hr figure.
personally I would leave the batteries on float charge whenever the amp was not being used.
mike
this size offers reasonably low internal resistance
I have found that they last for several days normal usage.
you can work it all out by dividing the average current consumption into the into the amp/hr figure.
personally I would leave the batteries on float charge whenever the amp was not being used.
mike
I've found some sealed-lead/calcium batteries...
Power-Sonic 12V/7AH for $15 retail. That's a lot more pricey than the lead-acid($10), but you never have to worry about acid leak.
I started looking into SLC's as a result of stumbling across a Jeff Riwland paper that explains hy they use SLC's in their " DC Power Supply (DCPS)"
J Rowland Battery supply
Of course, this could get pretty expensive (for the JR tube-buffered GC) once you take multiple chargers into account.
Well, maybe not if you consider a dual-mono supply using Plitron or other quality trannis - 4 x 160VA/24V ($70) for LM38735 and Heaters, and 2 x 15VA/6V ($50) filament toroids. That's $350+ with tax and shipping.
Going batteries:
4 x 12V/7AH ($15) for LM3875's
6 x 12V/7AH ($15) for heaters
2 x 6V/7AH ($15) for filaments
$180 for SLC batteries or $120 for SLA's
Chargers:
IBEX Manufacturing
2 x 12V/1A 115VAC chargers($80) for 4 LM3875 batteries
2x 6V/0.5A 115VAC chargers($45) for the filament batteries
The heater supply would shoot everything to hell, though. 36V would be really expensive to do both battery and charger wise if you wanted to use 3-mode intelligent chargers.
I've found some cheaper 2-mode cgargers, but don't know if they are ideal.
chargers
Power-Sonic 12V/7AH for $15 retail. That's a lot more pricey than the lead-acid($10), but you never have to worry about acid leak.
I started looking into SLC's as a result of stumbling across a Jeff Riwland paper that explains hy they use SLC's in their " DC Power Supply (DCPS)"
J Rowland Battery supply
Of course, this could get pretty expensive (for the JR tube-buffered GC) once you take multiple chargers into account.
Well, maybe not if you consider a dual-mono supply using Plitron or other quality trannis - 4 x 160VA/24V ($70) for LM38735 and Heaters, and 2 x 15VA/6V ($50) filament toroids. That's $350+ with tax and shipping.
Going batteries:
4 x 12V/7AH ($15) for LM3875's
6 x 12V/7AH ($15) for heaters
2 x 6V/7AH ($15) for filaments
$180 for SLC batteries or $120 for SLA's
Chargers:
IBEX Manufacturing
2 x 12V/1A 115VAC chargers($80) for 4 LM3875 batteries
2x 6V/0.5A 115VAC chargers($45) for the filament batteries
The heater supply would shoot everything to hell, though. 36V would be really expensive to do both battery and charger wise if you wanted to use 3-mode intelligent chargers.
I've found some cheaper 2-mode cgargers, but don't know if they are ideal.
chargers
Ok, well I got 4 12v 4.5AH Ultratech SLA's, from a home alarm store, at about $15 cdn each.
What about using this simple charger?
http://www.aaroncake.net/circuits/charger1.htm
Now all I need is to find time to make the chargers and go to solen and get some quality caps, they have nice prices for Cerafine caps and I'll try the bennic polyester caps for this project.
Should be done with all that next week, If I have time and if everything goes well.
What about using this simple charger?
http://www.aaroncake.net/circuits/charger1.htm
Now all I need is to find time to make the chargers and go to solen and get some quality caps, they have nice prices for Cerafine caps and I'll try the bennic polyester caps for this project.
Should be done with all that next week, If I have time and if everything goes well.
Texas Instruments has an IC that does it all...
The UC3906
Here's the TI application notes for the basic use UC3909 and provides simple circuits that do everything needed for a 4 phase charger:
1. Trickle charge for fully discharged or damaged batteries.
2. Bulk Charge; 80-90% of fast charge
3. Over-Charge; remaining 5% of charge
4. Float - maintaining max charge during extended non-use
I've got the flu right now, so it's hard to concentrate, but the above manual gives a pretty good step-by-step walkthrough of all the calculations necessary for designing a perfect charger.
The UC3906
Here's the TI application notes for the basic use UC3909 and provides simple circuits that do everything needed for a 4 phase charger:
1. Trickle charge for fully discharged or damaged batteries.
2. Bulk Charge; 80-90% of fast charge
3. Over-Charge; remaining 5% of charge
4. Float - maintaining max charge during extended non-use
I've got the flu right now, so it's hard to concentrate, but the above manual gives a pretty good step-by-step walkthrough of all the calculations necessary for designing a perfect charger.
I wonder, In cars, the charger is simply a voltage regulator that limits voltage to 14.5V, well what about doing the same? and as voltage will get near lets say 14.5v the current will get smaller and smaller unti it reaches 14.5v.
And for that I guess we need nothing more than a lm317 and like 3 resistors.
And for that I guess we need nothing more than a lm317 and like 3 resistors.
Funny, I'm looking at the spec sheet right now...
I like the idea of 3 or 4 phase charging rather than simple bulk charge, but if that works then lets do it.
If you use the LM317 in conjunction with and LM3647 and 4 resistors (page 3) it makes a universal battery charger that monitors voltage, tempeture, and current.
What do you think?
A better charger with minimal effort?
I like the idea of 3 or 4 phase charging rather than simple bulk charge, but if that works then lets do it.
If you use the LM317 in conjunction with and LM3647 and 4 resistors (page 3) it makes a universal battery charger that monitors voltage, tempeture, and current.
What do you think?
A better charger with minimal effort?
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