[Folsom]

Does anyone know the input impedance of the 50+50 Yuan Jing Blue Black board?  The website appears to be down or I would have looked it up myself.

Thanks,
Ed

It's based on gain, check the 3116 data sheet.

[rajacat]

For those interested, Astron SL-11A can also be adjusted to output 15V.

I went over the spec. sheet for both models and you're right. I didn't notice it the first time. I was wondering what was the difference between the R version and the A version. The R spec. sheet intro mentioned the adjustability but the A version intro didn't.
I was feeling lucky that I found one that has this feature.   

[Markvdv]

Standard gain for both YJ blue and red is set at 26dB, giving 30k input impedance. (sometimes wrong resistors are mounted, read about that a couple of times)
If you need or like 60k input impedance better just remove the left side 100k resistor for all other options you need to change resistors.

[HaroldHill]

...The R spec. sheet intro mentioned the adjustability but the A version intro didn't.
I was feeling lucky that I found one that has this feature.   

The only way I knew that the A version is adjustable is that I opened mine up and found the little thumbwheel and put it to use. 

[wushuliu]

The only way I knew that the A version is adjustable is that I opened mine up and found the little thumbwheel and put it to use. 

That's only an extra volt or so difference right. How much extra watts is that?

[randytsuch]

So I ordered from Audiobah on 6/17, got it yesterday on 7/2, about 2 weeks.

I'm in LA, so probably a little faster than other parts of the country.

Randy

[HaroldHill]

That's only an extra volt or so difference right. How much extra watts is that?

If I recall correctly, the thumbwheel covered a range from 12V to 15V. Would increasing the voltage simply decrease the amperage? Sorry...I'm not even sure when to apply Ohm's law...

[Folsom]

Who cares? It's got enough A for three units full blast, even if it did.

But to answer the question, no, it does not. The transformer in it and recifiers are probably upwards of 18-21v , and the rest I believe is shunted off (I looked at the schematic awhile ago, it could be switching limiter too on the output, but I remember liking the design so probably not)

[wushuliu]

Who cares? It's got enough A for three units full blast, even if it did.

But to answer the question, no, it does not. The transformer in it and recifiers are probably upwards of 18-21v , and the rest I believe is shunted off (I looked at the schematic awhile ago, it could be switching limiter too on the output, but I remember liking the design so probably not)

Him so could it by modified then to get the 18v straight?

[Folsom]

Him so could it by modified then to get the 18v straight?

It depends on what the actual rectified voltage happens to be. One could check the rails. However there's a loss of quality in the voltage regulation as a potential because if the AC 120v dips, at 15v the voltage may not, but at close to the rails it will. Also it may cause a significant reduction in any of the noise attenuation as the shunting is reduced to an insignificant amount.

Personally I'd say you're doing damn good for the price you paid already. Upgrades are possible not in the voltage increase.

* Lowering ESR/ESL properties on the shunt side may be an option for more filtration.
* high quality capacitors, as always, could be an option.

Maybe I'll get into it later, I can't in a timely manner on my phone.

[matt_garman]

Looks like Astron's LS- series has stock 28V output, but is adjustable down to 22V.

A quick ebay search didn't come up with any matches, so I don't think these are as common as the 12V PSUs.

$130 for a new LS-10A from Ham Radio Outlet.  Steep price increase for the next one up: $205 for an LS-18A.

[Markvdv]

Life of the Astron with these superefficient amps will be very easy, the Astron spec suggests you could run 2 boards, (Astron specs are looked at differently then other PSU specs, the SL11A is said to be really a 4 to 5A powersupply). But plenty of the headroom. A previous life of the Astron might not have been as easy as powering a little d-class amp, and the slim SL11A is said to get very hot, and in production since 1990? So I think capacitors is reasonable to look at, possible temperature and possible age considering. Google is giving very many hits, this one I could follow with my limited skill:

http://www.repeater-builder.com/astron/astron-repair/astron-repair.html

[lacro]

Is the wire gauge and length critical for best SQ from Astron PS to amp. I am currently using a very light gauge wire (20/22?) about 4' long because one end has the barrel connection to plug into my experimentation boards jack. 

[Folsom]

Is the wire gauge and length critical for best SQ from Astron PS to amp. I am currently using a very light gauge wire (20/22?) about 4' long because one end has the barrel connection to plug into my experimentation boards jack.

Theoretically, yes. The shorter any wire is the better. In practice? Well there's been a lot of "long" runs of wire and people still listening to music; considering people are always worried about the distance down to millimeters.

Sooo just try to keep it reasonable.

[Markvdv]

There are a lot of caraudio calculators online. 1 meter AWG20 for 13.8V and 40watt total amppower 85% efficient (gives ~3.5A) has ~250mV loss, 1 meter AWG 17 ~125mV loss. For caraudio they feel 500mV is acceptable. But no idea what effect this difference has on sound, sorry

[rhing]

Is the wire gauge and length critical for best SQ from Astron PS to amp. I am currently using a very light gauge wire (20/22?) about 4' long because one end has the barrel connection to plug into my experimentation boards jack.

Here's the calculator I use:

http://www.bulkwire.com/wireresistance.asp

I use a 1m twisted pair of Kimber 19AWG TCSS wire with a Switchcraft 2.1mm x 5.5mm DC power connector at the amp end with my Astron RS-12A linear power supply. 

[Markvdv]

The main difference between calculator I used and rhing's is mine doubles the lenght, cable lenght plus and min is added.

[OzarkTom]

I'm interested.
I'll be purchasing an Astron any day now.
I've also ordered the audiobah board.

Well, I am definitely buying one of these cables. 

I have been listening to quite a few cable combos because of the cable tours here on AC and several sets were so detailed that I lost the emotion and the magic. I had to put at least one soft sounding cable to get the magic back.

After hooking up this power cord to my Itube, the sound was too soft. So I then hooked up the detailed cable and that what I was needing. This power cable makes everything so sweet sounding, yet detailed, as the $300 Job Sweetcord cable I hooked up to my Sony music server does.

I ran out of time to try it on my TBI amp, so I will have to wait when I receive the cable I am buying. Another audiophile bought this for his Itube and is raving about it also. My buddy Rex is getting his on Wednesday, so I will see what he says.

[dboy]

Here is a bizarre curiosity for the consideration of you hardened 3116 wranglers: an Audiobah board with no input caps and no decoupling caps. I wrote about the removal of the input caps to mate with my Buffalo Dac with output transformers here:
 

I took the plunge...

Further to that I have made a very simple linear PSU using a Hexfred rectifier, Mundorf Mlytic 10,000uF 25v cap and Bybee Music Rail. The app notes for the Music Rail recommend to "Ensure that no output cap is present." So I removed the electrolytics from the board and then, not really being sure whether this was a good idea, I also removed the SMD decoupling caps, both close to the chip and where the power enters the board.

How does it sound? Pretty good so far. I think the Mundorf cap and the MR are not quite functioning at their best yet - probably had <20hrs use. I have noticed quite an improvement since first connected up and after listening for about 4hrs yesterday the sound really did open up and become quite liquid, with vocals hovering wonderfully in the 3d space in front of me. It has excellent resolution and presence and sounds better than I've personally heard a 3116 sound thus far - although I have not done major mods or been able to sample one of those Astron power supplies (they seem hard to get in the UK, with our higher mains voltage).

So far, the leap in performance of the TPA3116 board with the addition of the MR is not so dramatic as I enjoyed with TA2020. There is at the moment a slight hardness in the midrange and despite excellent promise, I would say that musicality lags behind my old Charlize amp that I had set up with Black Gates and no input caps. (That amp had fantastic synergy with the Buffalo Dac and was not just any old TA2020 amp). I suspect that I am hearing the difference now between the superior parts used for the Charlize and the cheaper parts used on the Audiobah.

I think the next thing I need to do is replace the inductors (as well as continue burn-in). I have read several recommendations, but in view of the limited space on the Audiobah board I wondered if there was a consensus on the best compact 22uH replacements people had tried? I'm not gonna be hanging those whoppers that Wushuliu and Rhing managed to fit to the blue/black off this little fella.

Also, I am considering that maybe I should have left the decoupling caps in for comparison as the app notes for the MR say they can be left in in certain conditions and only advised to remove them. Any constructive comments would be very welcome. I think I am on the way to something very good here... but not quite there yet.

[randytsuch]

Here is a bizarre curiosity for the consideration of you hardened 3116 wranglers: an Audiobah board with no input caps and no decoupling caps. I wrote about the removal of the input caps to mate with my Buffalo Dac with output transformers here:
 
Further to that I have made a very simple linear PSU using a Hexfred rectifier, Mundorf Mlytic 10,000uF 25v cap and Bybee Music Rail. The app notes for the Music Rail recommend to "Ensure that no output cap is present." So I removed the electrolytics from the board and then, not really being sure whether this was a good idea, I also removed the SMD decoupling caps, both close to the chip and where the power enters the board.


Also, I am considering that maybe I should have left the decoupling caps in for comparison as the app notes for the MR say they can be left in in certain conditions and only advised to remove them. Any constructive comments would be very welcome. I think I am on the way to something very good here... but not quite there yet.

Cool.
I have been thinking about making a simple linear.  I have a surplus transformer which I think will work, which is most of the cost.  I also have a bunch of bridges and caps I can use.  I was thinking about trying an unregulated PS, and since I don't have a Music Rail that won't be part of my supply.

I am curious how a simple linear would compare to the Astron, if I can find a Astron cheap enough I might compare one of these days.

And if it was me, I would at least stick the surface mount caps by the 3116 back in.  I would guess the MR doesn't like a lot of capacitance close by, but a little sm cap with some trace in between should be OK.

Randy