Hi,
What about capacitance at the output? One of the things that concerns me with modding gear with discrete power supplies is that some of these high performance circuits have stipulations on how much capacitance they can tolerate on their output - it's possible to make things worse than the good old 7812 etc. I guess.
-Raja
What about capacitance at the output? One of the things that concerns me with modding gear with discrete power supplies is that some of these high performance circuits have stipulations on how much capacitance they can tolerate on their output - it's possible to make things worse than the good old 7812 etc. I guess.
-Raja
Which makes perfect sense when you think about it.
With no load, or a pure resistive load, the output will be amazingly quiet and stable.
But in taking the output node and using it to bootstrap the reference, any noise coming back from an ACTIVE load, like an amp, could potentially inject noise back into the regulator and the virtuous circle becomes vicious.
A fix is easy though, just filter the bootstrap voltage with LC or RC before using it in the reference, and just leave the error amp powered by the rail.
Just my 2 cents.
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www.belleson.com shows available for sale a negative voltage regulator; i.e. an improved substitute for LM337. Informative and easy to surf site. The patent was granted. There is simultaneous text which still says patent pending.
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It's not noise we're concerned about, it's the modulation of the rails with harmonics of the fundamental. (The line amplifier used for the listening test was very low THD, but poor PSRR.)
...and when we think of PSRR we probably concern ourselves most with minimizing line harmonics, emi, etc. emanating from the supply end, what happens when you ping the rail with (for instance) a really loud and percussive sound is that the rail is splattered with harmonics.
it would be interesting to test the Belleson for reverse PSRR.
Interesting and informative thread; corrupt the power rails! Will two LM317s which are connected in series give any performance advantage? The first LM317 connected to the raw power supply shields the second in a manner like cascoding an amplifying transistor which is beneficial in this app.
The "euphonic" Burson reference is _not_ bootstrap powered by its output-- don't be confused by the name similarity of "Burson" and "Belleson."
Jack, please contact me via personal email if you do any further testing, I'd prefer that you test the most recent (and currently shipping) product version.
Brian Lowe
Maybe a stupid question but I can get my hands on a pair of Belleson +/- 18V 2A regulators. I would like to try them out in my preamp but unfortunatly I need +/- 15V. The website of Belleson states that the voltage is being set by only one transistor on the leg of a current source. Can this resistor be altered to ajust the regulators to +/- 15V instead of +/- 18V ?
Yes it is resistor "R12" on the schematic attached to post #1 in this thread (for the positive supply). The negative supply almost certainly has a mirror image schematic, where you would fool with R12_conjugate to adjust the output voltage.
Start with a trimpot, dial till you get what you want, measure R, and substitute a fixed resistor.
Just figured out that the regulators are completely dipped in epoxy, so no go in altering anything by myself. Too bad. Really wanted to try them, not gonna buy new ones. Shipping and import tax is way too high nowadays to order anything from the USA. Looking further for some good 2A regulators here in europe.
I agree that shipping costs are high, even via standard post. If it helps, Superpower are available from Parts Connexion in Canada.
Sjef, if the Belleson 18V regulators are still available, you are still interested and you can tell me the part type (SPJ17 or SPJ78) of the positive one, I can send a picture to show how to connect a resistor to bring Vout to 15V by adding a 13K7 resistor to the back side of the PCB.
Brian
Belleson LLC
Hi Brian, that's great news. Yes they are still available. It's a spj78 / spj79 pair at 18V/2A. I want to use them in my DEQX crossover wich requires +/- 15V. That's the voltage of the smps psu. After the smps there are is a lm317/337 pair adjusted at +/- 12V for the analog section and a dc/dc convertor for the digital section. Both are powered from the same +15V rail. I think I would get some more improvement by subtituting the lm317/337 pair for.the Belleson regulators but I would like to keep the main board in tact because in a case of any fault I'm not able.to repair it myself. Replacing the smps.for.a.lineair supply with some good regulators should give some improvememt I guess.
Thanks in advance
Sjef
Thanks in advance
Sjef
Hi Sjef,
See attached photos, the 13K7 goes between the red and blue nodes, blue is ground. The added resistor is in parallel with a 4K7 internal resistor and they share 2.5mA to set Vout. You may need to use 30 gauge wire-wrap wire to connect, also note that the holes will be epoxy filled.
A linear regulated supply should give improvement over the SMPS, but as you say the analog section won't have any better power source than the LM317/LM337 because they are in series with the Superpowers.
If the DC/DC can accept lower Vin, maybe consider dropping to 12V instead of 15V to power both analog and the DC/DC. But never mind, this requires removing the LM317/LM337 pair and you don't want to do that.
Also before you start, be aware that SPJ78/SPJ79 have no current limit and no thermal protection. Even a brief short from Vout to ground will damage a SPJ Superpower. Use Vin to the regulators as close to 16 or 17V as you can, to keep regulator power dissipation as low as possible. You don't say the current required for the system-- if it's above 1A the regulators will need heat sinks, even at Vin = 16V. Consider connecting and debugging with LM7815/LM7915 then when everything is working, replace with SPJ78/79.
Good luck!
Brian
See attached photos, the 13K7 goes between the red and blue nodes, blue is ground. The added resistor is in parallel with a 4K7 internal resistor and they share 2.5mA to set Vout. You may need to use 30 gauge wire-wrap wire to connect, also note that the holes will be epoxy filled.
A linear regulated supply should give improvement over the SMPS, but as you say the analog section won't have any better power source than the LM317/LM337 because they are in series with the Superpowers.
If the DC/DC can accept lower Vin, maybe consider dropping to 12V instead of 15V to power both analog and the DC/DC. But never mind, this requires removing the LM317/LM337 pair and you don't want to do that.
Also before you start, be aware that SPJ78/SPJ79 have no current limit and no thermal protection. Even a brief short from Vout to ground will damage a SPJ Superpower. Use Vin to the regulators as close to 16 or 17V as you can, to keep regulator power dissipation as low as possible. You don't say the current required for the system-- if it's above 1A the regulators will need heat sinks, even at Vin = 16V. Consider connecting and debugging with LM7815/LM7915 then when everything is working, replace with SPJ78/79.
Good luck!
Brian
Attachments
In the listening test, it should measure the specification of pre-amplifier that used with those regulators. How those regulator can affect to the performance of the pre-amplifier.
I designed several regulators, series and shunt. Those regulator was built by my friends and they claimed it was better than LM317/LM337. But I still do not understand what the most important of regulator specification in audio application. I just do the best I can using easy to find components in my country and make cheap as possible.
I designed several regulators, series and shunt. Those regulator was built by my friends and they claimed it was better than LM317/LM337. But I still do not understand what the most important of regulator specification in audio application. I just do the best I can using easy to find components in my country and make cheap as possible.
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