CurtPalme.com Home Theater Forum

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Mac or Curt or anyone who might have experiance if this would be ok.

I have an older Velodyne VA 1012 sub it has an 80 watt amp using a STK 4032II-M.

I was looking at similar STK's that have a higher output.

This STK says its a split power supply 40 watt: http://pdf1.alldatasheet.com/datasheet-pdf/view/41542/SANYO/STK4032II.html

I was wondering how high I could go?

I know if I go Higher I might have to up the transformer and the filtering caps
from 4700uf to 10,000uf that the higher watt amps IC show on the data sheet.

I was looking at this.

http://pdf1.alldatasheet.com/datasheet-pdf/view/41558/SANYO/STK4042XI.html

The STK in my Sub has a.4% distortion while this is .008%. And its an 80 watt split power supply so would that mean it will double my output to 160 watt amp since the STK 4032 is a 40 watt split power supply and that puts out 80 watts?

Any Advice? I now its an old Sub but it really does sound nice but I want to see if I can get any more power out of it.

It would also be a learning experience.

Thanks for the help.

Athanasios

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

I think your first problem to solve is the transformers. Neither gives you the AC output or wattage of the transformers. And you may not even have the listed one and your current one may be adequate.

I would test your current VCC +- and see where it's at.

**Curt Palme** · Posted: Fri Jan 25, 2013 8:03 pm Post subject:

I think you're going to a lot of effort for little to no reward. Remember that you need twice the power for a 3db increase, and if you add 3db via an equalizer to a system, it really is very little gain. If this is one of those servodrive units, then you can't mess with the amp stage at all. That was 20 years ago though, those servo units were HORRIBLE units. My guess is that it's a plain amp, in which case, get an aftermarket power amp and drive it that way. That would be your cheapest option.

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

ecrabb · Posted: Fri Jan 25, 2013 8:26 pm Post subject:

Athanasios - You're probably wasting your time. Subs are usually designed as a system, such that the amplifier, driver(s), and enclosure are matched in terms of output capability. Driver xmax, radiating area and system Q (impedance), and amplifier power are all interlinked. It's highly likely that the system output is limited only by the amplifier, in which case increasing amplifier won't accomplish anything.

Like Curt said, doubling the amplifier power will only result in a 3dB gain. So, if the sub's max SPL is 90dB now, it will be 93dB after you double the power - an audible, but neglible increase. Now, if you went from 40w to 500w, then you'd be talking about a significant, noticeable increase in SPL, but then you'd over-excursion and destroy the driver long before you ever got that SPL. With most of those older subs, the drivers aren't capable of much output in terms of xmax, which like I said, is what's really limiting overall system output.

Craigslist it for $75 and put the money into another toy. Wink

SC

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

I understand Steve, however as I said before. Its just a learning exercise and I might put a larger driver in the cabinet. There are
people who have up it to a 12 inch driver and then just tuned the passive radiator with more or less weight/ resistance. I have to see how this one is set up. Some use a bungee cord tying the radiator to the opposite wall and others use weight on it.

For a quick experiment I can take the sub line in to my adcom 200 watt amp's center channel and then run that to the sub and test
the sub with some low Frequency test tones. At least I can see what 200 watts does. The nice thing I can do it this way since the amp cabinet is sealed from the rest of the sub chamber.

What I'm after is not more spl but more extension. even just a little I'd be happy.

Athanasios

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Boy, talk about a bunch of nay sayers........ Where's your sense of adventure....... Laughing

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Here is the 100W Split Power supply.

http://pdf1.alldatasheet.com/datasheet-pdf/view/41561/SANYO/STK4044XI.html

And a 120W !!!

http://pdf1.alldatasheet.com/datasheet-pdf/view/41563/SANYO/STK4046XI.html

Also .008% THD compared to .4% of the original. SO if the Original is a 40w split power supply and output's 80 watts does that mean the 100W split Power supply will output 200W's?

Athanasios

ecrabb · Posted: Fri Jan 25, 2013 10:01 pm Post subject:

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Nashou

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Here is the transformer and rectifier.

barclay66 · Posted: Sat Jan 26, 2013 9:50 am Post subject:

barclay66 · Posted: Sat Jan 26, 2013 10:17 am Post subject:

Me again,

I just compared the datasheets. If the original part is a STK4032II You could use the STK4046XI instead if the following modifications were done:

- Replace the transformer with one having 2 x 48V output (configuration: [48V AC] - [Center Tap] - [48V AC]) at max. 3A per winding (should be rated at 250-300W). Will yield +/- 66V as recommended. Take care of other voltages needed as described in my previous post.

- Replace the bridge rectifier with a 400V/5A one.

- Replace the eletrolytic caps with 2 x 10,000µF and min. 80V.

- Replace the STK and modify the circuit as required (three additional pins now resulting in four outputs together with pin 13, additional inductor at the output and additional parts between pins 8 and 11).

- Replace the smaller caps near the supply pins (5, 12, 14 and 15) with ones supporting at least 100V.

That should be it...

Regards,
barclay66

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Thanks for the info Barclay, that 4046 might be too much work with the extra pins. So I think I might just go to the 100w STK4044XI

http://pdf1.alldatasheet.com/datasheet-pdf/view/41561/SANYO/STK4044XI.html

Looks like the same pinouts. So just the rectifier and transformer would need a change.

Athanasios

barclay66 · Posted: Sat Jan 26, 2013 2:57 pm Post subject:

Yep, that should work.
The transformer should have around 40 to 45 Volts and 200-250W then. Don't forget about the capacitors at the supply pins. The resistors and the inductor at the output seem quite important to me too...

Regards,
barclay66

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Thanks Barclay, HWat is your Name anyway?

I'll try to take pics of the board later today. I wish I has schematics.

But from 80 watts to 200 should be a nice improvement in control of the driver at least. And the lower distortion is what I like best.

But As mac says, the STK's are junk amps. But For a sub I think Its ok, never would use them in a stereo amp design.

Athanasios