Greetings from the thermionic emission side of the isle 
As you can probably tell by my username, I'm a toob kinda guy, so I'm just dipping my toes here.
I recently bought a pair of Extremis 6.8's to use from 300-400hz down in a tri-amp setup. Not wanting to drain the grid with a array of big hot tubes, and the AC needed to cool the room, I have decided to go over to the dark side () with a UCD180 on the woofers (SE tube elsewhere).
This brings me to my question. I found this surplus power supply (PDF attached), and I need the digi experts to tell me if it's suitable for a UCD180 mono-block driving a stable 8ohm load.
That is all.
-Casey
As you can probably tell by my username, I'm a toob kinda guy, so I'm just dipping my toes here.
I recently bought a pair of Extremis 6.8's to use from 300-400hz down in a tri-amp setup. Not wanting to drain the grid with a array of big hot tubes, and the AC needed to cool the room, I have decided to go over to the dark side (
) with a UCD180 on the woofers (SE tube elsewhere).This brings me to my question. I found this surplus power supply (PDF attached), and I need the digi experts to tell me if it's suitable for a UCD180 mono-block driving a stable 8ohm load.
That is all.
-Casey
This eBay store sells something similar (if not identical). It is a bit dearer but he provides detailed information and instruction on how to adapt the SMPS to your application.
Stadholder Tek
Modification instructions:-
Stadholder Tek
Modification instructions:-
+-45v @ 2A is pretty useless for a 4 or even 8 ohm load. You will be lucky to get a clean 25 watts of output power before the SMPS runs out of current. You would only be able to use the supplies full power with a high impedance load.
Don't skimp on your UCD project. Either take the money you would have wasted on those supplies and buy a proper transformer, or save up a little more and get a proper SMPS from coldamp.
Don't skimp on your UCD project. Either take the money you would have wasted on those supplies and buy a proper transformer, or save up a little more and get a proper SMPS from coldamp.
I don't know much about SMPS and I'm hoping to learn something here.
Just looking at the numbers - the Coldamp SPS30 is a 400W +/- supply - so it would provide 3.3A on each rail.
Combining two of these Lambda supplies would provide 4A on each 45V rail. If you are only interested in voltages of around +/-45....wouldn't this be suitable?
Just looking at the numbers - the Coldamp SPS30 is a 400W +/- supply - so it would provide 3.3A on each rail.
Combining two of these Lambda supplies would provide 4A on each 45V rail. If you are only interested in voltages of around +/-45....wouldn't this be suitable?
I didn't say in the start of this thread (my bad), but that was my thinking. After reading the link on Lambda mods posted by Fin, I became convinced that they could be modded to run in parallel (though the link doesn't say this specifically). So convinced in fact, that I ordered 6 of them..3 per channel for 6 amps continuous, 9 amps peak. Thats a little over a nickel a watt, and at 80 watts per unit, wont need any forced cooling
On another front, I have decided to hold off on digital for now. I just need an amp for upper bass/ lower mid and lower (Extremis 6.8 in a transmission line), and have decided that a BPA200 chip amp will give me twice the slam for the same price. This will also allow me to run a linear post regulator down to +/-35V for more noise reduction/stiffer supply.
Thanx all for your time...I'll be back I'm sure.
-Casey
Fin said:
You are overlooking the fact that the supplies from Coldamp can be requested in other voltages. A SPS30 with a voltage of +-35v @ 5.7A would be far more useful for 4-8 ohm loads than one with +-60v @ 3.3A.
I wouldn't use multiple SMPS to create a single supply if you can avoid it. Most SMPS have fairly high idle power consumption, so using multiple supplies will eat up quite a few watts even when there is no load.
The output current you are calculating that way is the continuous DC current allowable. As you said, a SPS30 outputs 400W and at +/-60V that means 3.3A continuous per rail.
However, the instantaneous current is much higher, for example, you can output a continuous sinewave of 110Vpp at 4 ohm. That means around 370W rms. If you calculate the peak current, it is 55/4=13.75A.
We can, of course, provide supplies with other voltages on request. Just drop us an e-mail to info@coldamp.com and we will be glad to help you.
Best regards,
Sergio
However, the instantaneous current is much higher, for example, you can output a continuous sinewave of 110Vpp at 4 ohm. That means around 370W rms. If you calculate the peak current, it is 55/4=13.75A.
We can, of course, provide supplies with other voltages on request. Just drop us an e-mail to info@coldamp.com and we will be glad to help you.
Best regards,
Sergio
If you read the comments at All Electronics I linked to, And The mod link from Fin, the real world output of this Lambda is around +/- 43V under load. With a handful of parts, and an afternoon you can make it anything from 30 somthing to 50 something without stressing it out. I'm leary of "switchers" in general, and plan to run a linear reg after it. So with a target of +/- 35V, 40 or so volts out of the switcher sounds about right.
This is a concern, I guess I'll find out if it's excessive or not, and if there is some kind of "stand by" scheme I can come up with.
I have little doubt that the Coldamp switcher is a fine product, and if I wasn't such a tight a** (have to be), I would give it a try.
-Casey
I found some information on what might need to be done in order to connect some of these supplies in parallel.
It is from this Site:-High Efficiency Power Converter
Does this help in any way?
It is from this Site:-High Efficiency Power Converter
Does this help in any way?
Bigtime
I hadn't considered this was possible, I assumed the filter caps on the output would take care of this. A simple diode on the output would prevent this. I wonder what a ORing diode is
.I'll have to read the whole thing to be sure they're not talking about paralleling the switchers before the caps.
Thanx.
-Casey
Not suprising, they have a rep to maintain, and would surely advise against using there product "out of spec".
To be clear, I do not intend on hooking the outputs directly together. They would go through a load balancing resistor network first (think emitter resistors in a power amp). I need to "burn" off 8V anyway, so a half a volt or so across a resistor is no big deal before the linear reg.
I will be doing some breadboarding before I arrive at the final scheme.
-Casey
This will be before the linear regulators, so I don't see it affecting performance in any real way.
Just to give an idea as to how robust these supplies are, here's a snip of a review from a user of these supplies...
This guy apparently strapped 2 supplies directly together (not my plan) with no ill effects.
Between blocking diodes, and sharing resistors, with a post reg., I see no reason this won't work.
-Casey
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