- Posted by mikeyb (A) on May 08, 2007 at 10:17:22
In Reply to: SLA cells are cheapie like borsch. posted by cheap-Jack on May 8, 2007 at 08:13:16:
Whta are 'SLA' cells? I have never heard the term.
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In Reply to: SLA cells are cheapie like borsch. posted by cheap-Jack on May 8, 2007 at 08:13:16:
Whta are 'SLA' cells? I have never heard the term.
...usually contain a gelled electrolyte and so can usually be used in any position compared to liquid electrolyte as in automobile battery. The SLA has some advantages over the common NiCad but low weight isn't one of them.
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A SLA with a wide bandwidth series inductor?dave
Hi.Battery, dry or wet, is a very complex AC network by itself, techncally much worse than a capacitor.
To provide a bypass for the return signals, I installed a 5uF250VAC fan-motor cap, & a 333nF250VAC PP box film cap parallel to the battry O/P terminals. Also 2uF100V PE box film cap at the heater
DC supply I/P in the phonostage side.If the idea of addding a "wideband" series inductor is to remove the RF noises emitted from the SM charging board, then it would be needed.
As when the SLA cell is draining to power the tube heaters, the SMPS board is swithced off & electrically totally disconnected from the battery circuit. Of course, I already add RF ferrous suppressor ring onto the phonostage power cord as well as the DC O/P power cord of the batttery power pack as a RF safeguard.
c-J
the last thing you want to do is bypass the battery. since AC signal (your music) will appear on the + terminal it has two choices to get to audio ground. through the DCR of the filament or through the impedance of the filament supply. The wideband series choke prevents the music from using the battery as a path to ground.dave
Hi.Do I still need a wideband choke?
c-J
If you want to go down the SLA road you're going to need big batteries and efficient chargers - another poster suggested a 30 which is a fraction of the consumption and a very good DHT - one of a number of DHTs originally intended for battery use, which are typically 60mA to 120mA. But I will say that in a test of several different filament supplies, the batteries were not clear winners as one might expect, so don't expect miracles. And do expect to do a lot of recharging batteries rather than having a build-and-forget solution.
Hi.If you want PURE DC to power the tube filaments, what can be better than a rechargeable cell like SLA, cheap to own & no hassles to run.
I am using one for my phonostage heaters (0.6A6.3V) powered by a small 5AH cell, rechargeable by a switch-mode PS. The whole outboard power supply pack, comprising the SLA cell, the SMPS board & charge/discharge swithces/LED indicators/voltage check-points, etc, is DIY built in a small cheapie plastic equipment box (7"x2.75"x4.5"). It looks cool & neat, sitting beside my phonostage/linestage.
This is my "build-and-forget" pure DC supply solution for my phonostage tube heaters. No "miracles" if you know the way.
For 1A or larger current loads, you can go for 7AH or high rating.
One cell can do it all.c-J
PS: Any battery, dry or wet, is a complex AC network itself. Something got to be done to make it sound good. SLA cells are no exceptions.
'This is my "build-and-forget" pure DC supply solution for my phonostage tube heaters.'Really ? It seems that you built it then forgot a battery does not maintain it's charge . I bet a 5AH cell only has around four hours use , less if you've purchased cheap batteries which have past their shelf life date . How do you keep the heaters within +/- 5% of 6.3 volt for the heaters ? A much better solution would be to use an extra SLA in series and a CCS between the heater supply and the battery . This would maintain the heater supply at optimal conditions , even when the batteries begin to drain .
HI.Being a very very busy guy, I seldom get the luxury of 5-hour (!!) session for my vinyls.
BTW, you ever touch vinyls? If not yet, don't try it, amen!
Here is 'routine' rituals I go through to play a vinyl, put the LP on, secure it with the disc stabilizer, inspect & clean the stylus, check the DYNAMIC balance of the cartridge/stylus, wet the disc with pure distilled water (ad I always play wet), check the motor speed again, then lower the cartridge to the right track dead-slow manaully using the turntable hydraulic lever..........
But before I start these sorta painful rituals, everytime I check the cell voltage first, monitored by a dedicated voltage digital meter always inserted to the voltage check points installed on the power pack housing. I push the quick-charge button to start charging the cell if found drop a bit too low. This is always done before I start to exercise my time consuming LP routine rituals.
So far so good. Well, it worths the "pain" considering the joy of
musical enjoyment & sorta being-there engagement that only vinyl can offer.c-J
PS: Your CCS suggestion is correct, technically. But as a vinyl fan, I try to refrain from any SS sonic pollution after going such a long long way.
Neato, Jack. I've never heard of this being done.I've thought about doing this before, but didn't because I thought that the water would trap more airborne dust and cake it to the record's surface.
It really sounds like a good idea with many benefits (noise reduction and heat dispersal being the big ones) but I have a concern: does the viscosity (albeit very low viscosity) of the water affect in any noticable way the cantilever's recovery time? I realize that the resistance of pure water is going to be very low, especially when the force is being exerted by a recovering (returning to zero on axis) low-compliance cartridge, but it still seems that there would be a noticable affect...probably an audibly positive one.
I like the idea. I'm going to try it!
...esp when cost is factored in.
