DIY Purifi Amp builds

[JimB]

If we keep beating on this we will figure it out. Thanks for all the information so far.
JimM

What's needed to use an SMPS1200 is clear. What the best implementation is, for any one of us, remains an individual decision.

A. Just need it to run? Use the Purifi cable and put the other end on it as described, above:
One may simply insert the free ends of the EVAL1 J3 cable into the proper holes of the spare plug body to get an operational amp system using SMPS1200 J5:

B. Want to also use the nAMPON and nFATAL interlocks? Then provide either a full ribbon cable to the SMPS1200 J4, or adapt to it starting from the Purifi cable, as described, above:
Regarding wiring the free ends of the Purifi-provided J3 cable to J4 of the SMPS1200, the provided wires appear to be 22 AWG. Most IDC sockets accept only 26-28 AWG. The largest I have found DO extend to 22 AWG, and accept discrete wires, but are pricey. For example, the 3M CHG-2010-J01010-KEP‎:
http://multimedia.3m.com/mws/media/...r-wm-skt-100x-100-2-row-chg-series-ts0192.pdf

Even so, we still need two more wires, with crimps, to complete a 5-wire cable from the EVAL1 to the SMPS1200. @JimM found those here:
https://www.digikey.com/products/en...f=0&quantity=&ColumnSort=0&page=1&pageSize=25

Alternatives?
1. Do not use the provided cable for EVAL1 J3, and make up a ribbon cable with crimps on the end to load into the spare 7-position J3 plug; or
2. SPLICE the wires from the Purifi J3 cable to wires of a ribbon cable that mates with J4 of the SMPS1200.

 

[JimB]

I can not find version level on my SMPS on the sticker attached to the capacitors it shows build 3719 wk/yr which would be july of 2019. ...

I'm sure your rev is fine. But DO double-check that it is an SMPS1200A400, not an SMPS1200A700. I say that because I can find the A700 model on the website where you bought it, but not an A400.

 

[JimB]

Was a definitive conclusion reached for that question? Is it necessary? ...
Unrelated, is there a minimum gauge recommended for the wires from inlet to SMPS 1200 J2?

You absolutely need to provide +VUNREG power to the EVAL1 J3 connector.

Mains input leads? I use 16 AWG.

 

[JimM]

I have ordered (12in) jumpers from digikey with the JST EH series connections on the ends to install in the connectors to connect from EH shells to, connect more stuff such as input J5.1 to control SMPS standby. Also have ordered breakout pc boards for idc 10 pin to see if can also interface smps j4 functions. I think I have a scheme to at least control smps standby via remote from preamp. After I get all the stuff in will follow up with results. By the way what fuse value did you use on ac in? I'm 120VAC and was thinking 9 (1080watts) or 10 amp (1200watts) fuse which should give me a little margin, as I think the SMPS has a 13a fuse. For check out will use a 2 or 5 amp for playing around. Are you guys in U.S. or overseas, the reason I'm asking is show where the stuff I'm buying is of interest.
JimM

 

[JimB]

I have ordered (12in) jumpers from digikey with the JST EH series connections on the ends to install in the connectors to connect from EH shells to, connect more stuff such as input J5.1 to control SMPS standby. ...

I'm 120VAC and was thinking 9 (1080watts) or 10 amp (1200watts) fuse

Nice find! Those jumpers appear to match what Purifi uses, exactly! With 5 wires from EVAL1 J3 to SMPS1200 J4, you'll have it all. With two of those extra jumpers, you could wire directly to a suitable IDC plug like the one I referenced, above, 3M CHG-2010-J01010-KEP‎.
http://multimedia.3m.com/mws/media/...r-wm-skt-100x-100-2-row-chg-series-ts0192.pdf

Depending how you expect to use your system, 8A might be fine. That works for over 800W continuous amp output (2*400W), and you really should never be running continuously at over about 1/3 of that for music.

 

[JimB]

Looking at the prototype, the ribbon from SMPS 1200 J4 appears cut down by the time it connects to EVAL-1 J3? Forgive another newb inquiry but is that a common occurrence (the cutdown)?

Read the recent posts in this thread to see what wires are needed between those two connectors. Any other socket positions (or wires) do not matter.

 

[LondonLad]

Confirming. Like so:

 

[LondonLad]

 

[LondonLad]

And alternatively, could it be:

EVAL1 J3 to SMPS1200 J4

p5 to p1
p6 to p3
p7 to p2

With jumpers J6-J7 set to unregulated.

Unless I've gotten it wrong, it appears that this is how the prototype is wired, which would clear up a lot of confusion on my part.

 

[JimB]

View attachment 45694

Your cable looks right to me. You do have 220V mains, right? If 120VAC, then you would need to add a jumper to short the two pins together at J3 of the SMPS1200.

 

[JimB]

And alternatively, could it be:

EVAL1 J3 to SMPS1200 J4

p5 to p1
p6 to p3
p7 to p2

With jumpers J6-J7 set to unregulated.

Unless I've gotten it wrong, it appears that this is how the prototype is wired, which would clear up a lot of confusion on my part.

Yes. And I have corrected an error in the table, here:
https://www.audiosciencereview.com/...iy-purifi-amp-builds.10478/page-9#post-298679

 

[JimB]

You are right and sorry for my indefinite description; SMPS1200 J4.6 connects to EVAL1 J3.1 and SMPS1200 J4.10 to EVAL1 J3.3 it will give you soft start, eval board switch bypass features and SMPS can switch the power off when amplifier in trouble.

Same connectors contain +18V / -18V / GND for the eval board, just set jumpers to "unregulated power" on SMPS before use it;

SMPS1200 J4.1 -> EVAL1 J3.5 +18V
SMPS1200 J4.2 -> EVAL1 J3.6 GND
SMPS1200 J4.3 -> EVAL1 J3.7 -18V

5V DC supply; I did not use it, I had a 12-24V DC -> 5V DC supply in my electronic gadgets drawer , so I use the SMPS 18V rail to feed external circuits with 5V and never let SMPS to go standby mode. If you have an AC 110-220V -> 5V DC supply, than you can do real standby mode.

There is an error in the instructions above - the connections from J4.2&.3 to J3.6&.7 are reversed. The correct assignments are:

The first two connections to the EVAL1 J3 are optional, but the last three are required. If using an SMPS1200, those three required connections can come from either J4 or J5, as described, in the posts, above.

 

[LondonLad]

Alternatives?
1. Do not use the provided cable for EVAL1 J3, and make up a ribbon cable with crimps on the end to load into the spare 7-position J3 plug; or
2. SPLICE the wires from the Purifi J3 cable to wires of a ribbon cable that mates with J4 of the SMPS1200.

Bad practice to just use jumpers?

 

[JimB]

Bad practice to just use jumpers?

Maybe okay for a quick test. I cannot confirm the contact quality you will achieve at the the EVAL1 end. And they are more likely to come off over time, especially on the EVAL1 end. Also, I prefer not to have such loose, point to point connections where they could get installed incorrectly, especially when all are the same color wire, and they are for bipolar power.

 

[LondonLad]

I am also thinking of following your suggestion #2 above, i.e., "2. SPLICE the wires from the Purifi J3 cable to wires of a ribbon cable that mates with J4 of the SMPS1200."

How would you recommend that splice get done? I looked for a YT video on the subject but can't seem to find anything illustrative.

 

[JimB]

I am also thinking of following your suggestion #2 above, i.e., "2. SPLICE the wires from the Purifi J3 cable to wires of a ribbon cable that mates with J4 of the SMPS1200."

How would you recommend that splice get done? I looked for a YT video on the subject but can't seem to find anything illustrative.

Strip each end where you are going to join them, then twist and and solder them together, using a bit of heatshrink tubing to prevent shorting between them. To avoid having a large lump at one place, you can stagger the position of each splice, something like this:

I'd do this close to the J4 end, to keep some benefit of the heavier gauge provided by the Purifi wires.

 

[JimB]

In the demo amp (here: https://www.audiosciencereview.com/...of-purifi-1et400a-amplifier.7984/#post-194274), Purifi put a lighted switch on the front panel. Several of us have wondered about what it does, electrically, and how it was implemented. It was wired to the (currently unpopulated) J2 of the EVAL1 board. Yet the functions described on that connector do not support whatever that front panel switch is doing. On close inspection, there are two pairs of wires from the switch to connector J2: one likely for the switch (which is push-push); and the other for the lamp. In both cases, one wire of the pair connects to a Gnd pin of J2 (p2 and 10), while the other connects to a pin with no connection on the EVAL1 board (p4 and 8). Thus, it is likely that they jumpered two wires under the board from points they wanted, to available pins 4 and 8, for a cable header to get off the board. I assume one of the pairs asserts (pulls to ground) AMPON, instead of switch S1. The other is likely powered when the board is on, so the front panel indicates when it is active - maybe from pin 35 of the 1ET400A (AMP READY), IF it has enough drive to power an LED. That is what I see. Others might have more information. Regardless, this is not a way I want to implement my amps.

 

[LondonLad]

My build works as predicted. Strong control over low to mid bass in my system. Sounds good to me as-is stock out of the box.

 

[JimB]

My build works as predicted. Strong control over low to mid bass in my system. Sounds good to me as-is stock out of the box.

Nice! In a box, yet? Photos of it to share, inside and out?

 

[tmortimer]

My build works as predicted. Strong control over low to mid bass in my system. Sounds good to me as-is stock out of the box.

Did you make use of the ampon/fatal connections? Any additional stuff such as trigger inputs or standby?