DIY Purifi Amp builds

[Billy Budapest]

The degradation is that it introduces a point of failure. The solder is harder than the copper and can break off, and it and strands of copper can migrate out and cause shorts. That’s why they tell you not to do that.

 

[JimB]

It's also the solution that I do ... And it work properly, without destruction by the time

I have never had a failure from doing it. I have had a few issues when I have not done it. It could matter how the lead is used and connected.

 

[mikebarney]

New Purifi amp build completed using a vintage Audio Research chassis. Details here:
https://sites.google.com/view/mpbspurifiamplifierproject/home
Mike

 

[JimB]

New Purifi amp build completed using a vintage Audio Research chassis. Details here:
https://sites.google.com/view/mpbspurifiamplifierproject/home
Mike
View attachment 62472

Do you think that chassis provides ADEQUATE COOLING???

 

[mikebarney]

Do you think that chassis provides ADEQUATE COOLING???

Jim-
Not sure if that's sarcasm or not...
The mounting plate holding the active circuitry barely gets warm.
Mike
PS Thanks for all your contributions to this thread - I referenced your posts a couple times in my writeup.

 

[JimB]

Jim-
Not sure if that's sarcasm or not...

added...

 

[Matias]

New Purifi amp build completed using a vintage Audio Research chassis. Details here:
https://sites.google.com/view/mpbspurifiamplifierproject/home
Mike
View attachment 62472

Awesome. I bet it would confuse so many people in a blind test.

 

[JimB]

The degradation is that it introduces a point of failure. The solder is harder than the copper and can break off, and it and strands of copper can migrate out and cause shorts. That’s why they tell you not to do that.

Thanks to @Billy Budapest for sending me a great instructional video on recommended practices for assembling SpeakOn connectors. I don't have a lot of experience with SpeakOns, though I do use them on my main system (6 of them at the amp end) on custom cables I made. I'll just say that I would never use a tinned lead with the little clamp/shims in the Neutrik cups. I assembled mine, 'dry'. But I do tin tips in many cases where I assemble and disassemble the stranded wire connection, such as through a binding post if I am not using a spade.

 

[Billy Budapest]

No problem! I sent the video more for amusement than instruction!

 

[PNWer]

Don't see anything about a 12v trigger ;`(

I emailed https://vacuumtubevalues.com/vtv-amplifier/ in April
about a 3 channel Purifi modules, powered with just one Hypex SMPS 1200A400 power supply, with a 12 V trigger.
The reply was he would work on the design, with a target release in May when he received a bigger amplifier case.
I checked again last week, this amplifier was still 2 weeks away.

Since I'm in US, shipping charges for VTV-amplifier would be lower.
If Amir is interested I will have it drop shipped to ASR for testing to see its performance.

The power output of Purifi would be a nice fit for me since my speakers are 85 db sensitivity Philharmonic Audio.

 

[phoenixdogfan]

New Purifi amp build completed using a vintage Audio Research chassis. Details here:
https://sites.google.com/view/mpbspurifiamplifierproject/home
Mike
iView attachment 62472

I have a question on the heat sinks on the bottom of the Eval 1 and the SMPS. Do you unscrew them, place them under the EVAL 1 and rebolt the whole thing to the chasis, or are they meant to not be unbolted and rather have separate screws be placed into the holes on the bottom of the heat sink, or should i just bolt the completely open holes to the bottom of the case. And do I need any stand offs b/c it seems like the head sink should directly contact the floor of the case to augment the heat sink effect? Is that correct?

I don't see that Purifi supplied any screws or other hardware, so if I need additional screws or bolts or standoffs, what should I order? And where?

I know these questions seem ridiculously basic, but I'm down to the nitty-gritty here, and basic is where the rubber meets the road.

 

[boXem]

I have a question on the heat sinks on the bottom of the Eval 1 and the SMPS. Do you unscrew them, place them under the EVAL 1 and rebolt the whole thing to the chasis, or are they meant to not be unbolted and rather have separate screws be placed into the holes on the bottom of the heat sink, or should i just bolt the completely open holes to the bottom of the case. And do I need any stand offs b/c it seems like the head sink should directly contact the floor of the case to augment the heat sink effect? Is that correct?

I don't see that Purifi supplied any screws or other hardware, so if I need additional screws or bolts or standoffs, what should I order? And where?

I know these questions seem ridiculously basic, but I'm down to the nitty-gritty here, and basic is where the rubber meets the road.

They have threaded holes for fixation to the chassis. Nothing to dismantle. Unbox, screw, done. Fixation screws are not part of the delivery, you need M3 screws that enter max 4mm into the heatsink. With a 2mm thick chassis, M3x6 is perfect.

 

[phoenixdogfan]

They have threaded holes for fixation to the chassis. Nothing to dismantle. Unbox, screw, done. Fixation screws are not part of the delivery, you need M3 screws that enter max 4mm into the heatsink. With a 2mm thick chassis, M3x6 is perfect.

Exactly what I wanted to know, thank you.

 

[phoenixdogfan]

and even if the purifi does not heat much with a thin layer of thermal paste it will be perfect
bellow the rear of the eval1
you need 2x 4 for the 1ET400 and 2 more for the connection board View attachment 63081

Just got a set of screws from Amazon along with allen wrench. Thermal paste under both the heat sinks of the two amps and the Smps is a great idea. Still waiting for the SMPS which is out of stock. When it comes I will have all the pieces.

I am also following the "pin 1" discussion. Does the Eval 1 as used right out of the box properly ground out pin 1? In other words, if I just connect an XLR cable to the jacks supplied with the board, will Pin 1 be properly grounded assuming the board is fastened properly to the bottom of a metal chasis like the Ghent, providing I have a 5 hole back panel fabricated? Or if I just use three XLR pins into each eval 1 jack and then soldering those pins directly to the suplied back panel of the Ghent XLR inputs would that properly ground out the XLR inputs as well, or do I need to do something else?

 

[barrows]

Just got a set of screws from Amazon along with allen wrench. Thermal paste under both the heat sinks of the two amps and the Smps is a great idea. Still waiting for the SMPS which is out of stock. When it comes I will have all the pieces.

I am also following the "pin 1" discussion. Does the Eval 1 as used right out of the box properly ground out pin 1? In other words, if I just connect an XLR cable to the jacks supplied with the board, will Pin 1 be properly grounded assuming the board is fastened properly to the bottom of a metal chasis like the Ghent, providing I have a 5 hole back panel fabricated? Or if I just use three XLR pins into each eval 1 jack and then soldering those pins directly to the suplied back panel of the Ghent XLR inputs would that properly ground out the XLR inputs as well, or do I need to do something else?

Yes, pin 1 will be at ground, just make sure that the heat sinks under the modules make good contact with the chassis, you should remove some paint/anodizing on the chassis to be sure. It is still probably better to connect pin 1 directly to the chassis, I did this on my build, but I removed the XLR jacks on the eval board, and used separate jacks with wiring.

 

[phoenixdogfan]

Yes, pin 1 will be at ground, just make sure that the heat sinks under the modules make good contact with the chassis, you should remove some paint/anodizing on the chassis to be sure. It is still probably better to connect pin 1 directly to the chassis, I did this on my build, but I removed the XLR jacks on the eval board, and used separate jacks with wiring.

Thank you. I'm going to follow you advice re removing some of the annodizing under the heat sinks. I will be keeping the supplied XLR jacks on the Eval 1, so I'll have no need to connect directly to the chasisl

 

[Count Arthur]

Thank you. I'm going to follow you advice re removing some of the annodizing under the heat sinks. I will be keeping the supplied XLR jacks on the Eval 1, so I'll have no need to connect directly to the chasisl

Rather than do that, you could use a thermal pad or paste between the heatsink and the chassis, then remove the anodising around one of the screw holes on the outside of the chassis.

 

[barrows]

Rather than do that, you could use a thermal pad or paste between the heatsink and the chassis, then remove the anodising around one of the screw holes on the outside of the chassis.

The heatsinks need to make electrical contact with the chassis (for grounding and RF reasons), hence the need to remove some of the paint/anodizing. this is not for heat transfer rasons. And, there is no need for thermal compound between the sinks and the chassis, Bruno Putzeys has mentioned this before regarding the NC-400 modules. This is because there is so much area making contact the thermal transfer will be good without it. the thermal compound is really messy and totally not needed. Just make sure the surfaces are clean (wipe down with alcohol) and firmly bolted together.
I have been running my Purifi build for awhile now, even at very high volumes, they make very little heat anyway.

 

[boXem]

The heatsinks need to make electrical contact with the chassis (for grounding and RF reasons), hence the need to remove some of the paint/anodizing. this is not for heat transfer rasons. And, there is no need for thermal compound between the sinks and the chassis, Bruno Putzeys has mentioned this before regarding the NC-400 modules. This is because there is so much area making contact the thermal transfer will be good without it. the thermal compound is really messy and totally not needed. Just make sure the surfaces are clean (wire down with alcohol) and firmly bolted together.
I have been running my Purifi build for awhile now, even at very high volumes, they make very little heat anyway.

Having played with an NC1200 recently (the dummy load is still in convalescence), cooling trough chassis is mandatory if you want to be able to sustain some power permanently (something like 120W pink noise continuous in 2 ohms). Then removing the paint becomes mandatory, thermal compound is a nice plus. And no, an NC1200 and a 1ET400 are not night and day for efficiency.
Some air flow is nice to have too.

 

[barrows]

Having played with an NC1200 recently (the dummy load is still in convalescence), cooling trough chassis is mandatory if you want to be able to sustain some power permanently (something like 120W pink noise continuous in 2 ohms). Then removing the paint becomes mandatory, thermal compound is a nice plus. And no, an NC1200 and a 1ET400 are not night and day for efficiency.
Some air flow is nice to have too.

I have an NC-1200 based amp here (Merrill Audio Veritas twins) it runs very hot in comparison to the Purifi on the same load. The Purfif amps with a single SMPS 1200 run barely warm, even cranking Tool at "11" for an hour on my 4 ohm speakers. Hence I had total confidence in putting my stereo build in a non-ventilated chassis. This is really a night and day difference in terms of heat in the real world. I will try and take a pic of my build later today to share with folks here.