JS-2 Power Supply

[Superdad]

5 hours ago, ikemi said:

Many people on this form talk about using one linear power supply to power another linear power supply. How does that work and what are the benefits if any of going that? 

 

Hi Ron:

Well the JS-2 is a full AC>DC dual-output, choke-filtered, 5-7.4 amp linear power supply.  One can not power it with some other LPS.

 

However, there are some DC>DC power supplies (including a somewhat popular DIY board brand) which take DC in at one voltage (just about the target output voltage) and run that though low-noise regulators to then output DC.

 

And then there is the unique case of our own UltraCap LPS-1.2, which must be "energized"/charged from an external DC supply. With that model we include a customized 36W SMPS as charger. We do not think there is any benefit to charging the UltraCap LPS-1.2 from a linear supply. [If you study the design of our UltraCap model, you will see that the bank of capacitors connected to the cascaded and paralleled ultra-low-noise output voltage regulators at any given moment are disconnected from the charging power domain. The other bank is being charged at that moment--and then we alternate.]

 

I hope the above information is helpful to you.  And welcome to the Audiophile Style forums!

--Alex C.

[Superdad]

40 minutes ago, davide256 said:

I like the Linear Tube Audio MZ2 I have, it performs amazingly well as a 1 watt class A amp with my Magnepan 1.7 speakers using the JS-2 for DC power supply. I'm thinking of pairing the MZ2 with their Zotl 10MkII amplifier as I think that would give me the added db's I need but would prefer to use

(trust) a JS-2 instead of their LPS for stablity under full PS load. Can a JS-2 be configured to support this?

"The ZOTL10 comes with a power supply that supplies 10A of 24V. "

 

Hi Dave:

A nice thought, however:

a) the JS-2 definitely can not be configured to produce 24V;

b) at 12V, 7.4 amps (with full 12VAC input) is the max we can continuously output;

c) the LTA ZOTL10 MkII already comes with a nice PS with Belleson regulators;

d) the supply it uses may in fact be a bi-polar (+ and -) DC supply, whereas the JS-2 is just +DC.

 

I always like to give a complete answer--and to learn about other products which use external DC supplies. So when my Googling did not turn up details on the LTA supply other than seeing that it uses a Neutrik SpeakON connector (which can be anywhere from 2-pole to 6-pole), I decided to give Linear Tube Audio a call.

I met David Berning (of ZOTL fame) decades ago, when he was offering his tube amp as the ultimate car stereo amp! And I was tickled to see how Mark Schneider has expanded the ZOTL offering to a whole range of models in just a few years. While Mark is not who answered the phone, I had a pleasant chat with a fellow there who already knew of UpTone and who owns a Sonore ultraRendu. He is going to get back to me with further details about the PS for the LTA ZOTL10 MkII (most specifically if it is a bi-polar supply). I'll pass along anything new or interesting. BTW, I mentioned to him that you are using their MZ2 to drive your Maggie 1.7s and the shock in his voice was priceless! 

 

Cheers,

--Alex C.

[Superdad]

1 hour ago, davide256 said:

"The ZOTL10 comes with a power supply that supplies 10A of 24V. "

 

So I just received a very nice and informative reply from LTA, and it is very much worth sharing because it turns out the external PS box for their ZOTL10 is not a complete supply.  Here is the what was said:

 

Alex - 

Good to talk to you just now. 

As we discussed, there is no (easy) way to use an external power supply with the ZOTL10 Mk II. Most of the power supply is inside the amp, it's just the toroidal transformer that's in the external chassis.

It uses a full wave rectifier, so it's + and -, though - is treated as 0 volts. The umbilical we use is four conductor, but we only use three for the ZOTL 10 Mk II.

If you or the customer has any other questions, just let me know!

Stay healthy, stay safe!

Nicholas Tolson

Director, Sales & Marketing // Linear Tube Audio

301.448.1534

[Superdad]

3 hours ago, davide256 said:

Configuration: JS-2 optioned at 2x12V DC connected to NUC8i7BEH as USB audio source and LTA Microzotl 2 as headphone/speaker amplifier

With either DAC USB connected to NUC  and RCA connected to MZ2 I get a background of random computer noise on all connected/unconnected RCA inputs, noise

volume level remains basically the same regardless of volume knob position. Putting the original MZ2 power supply into use for either component eliminates the problem.

 

Hi David:

Thanks for your message.  You are forming a loop--from your JS-2, to the NUC, to your DAC, to your amp, and back to the JS-2.

 

The JS-2’s DC outputs are “floated” (though the chassis and shield of the transformer are grounded to AC mains for safety) and separately regulated.

Yet the two -VE/0-volt “grounds” of the JS-2’s separately regulated outputs are common to each other (because only one R-core transformer secondary, one set of Schottky diodes, one large filter choke). 

 

You could try connecting one of components back to AC mains ground to see if that eliminates the issue.

The JS-2 chassis screws are common to its AC inlet ground pin, and since it is the whole -VE/0-volt DC "ground" domain I am suggesting you try grounding, you could just as a test touch one end of a wire to a JS-2 chrome-plated top cover screw and the other end to the shell/barrel of any of the DC plugs. I'm not promising that will solve it, but if it does we can work with you towards a cleaner implementation of that.

 

Best,

--Alex C.

[Superdad]

27 minutes ago, davide256 said:

Thanks, will test and report back. Had turned all gear off last night, JS-2 connected to both components again, no symptoms right now, waiting for noise to come back.

 

Well I would not think that would be something intermittent.  Is there a chance that you have also have some other connection in common? For example (and we have seen this before) say an HDMI video cable from your NUC to a TV, and also from that TV to your amp?  You can see how that too would form a side loop of ground domains.

[Superdad]

2 hours ago, jacques_racine said:

Would you know what cable I need to power a Sonicorbiter i7?

 

1 hour ago, MrDerrick said:

I believe the STi7 end is a 7.4 x 5.0 mm inlet.

 

That is correct.  And here is an adapter that takes 5.5mm x 2.5mm at its rear and exits with a 7.4mm x 5.0mm plug:

https://www.bixpower.com/CNT-C24-p/cnt-c24.htm