DIY Purifi Amp builds

[kaka89]

https://www.audiophonics.fr/en/powe...eo-amplifier-purifi-2x400w-4-ohm-p-14557.html

Audiophnics new amp:

Kaluga

 

[boXem]

https://www.audiophonics.fr/en/powe...eo-amplifier-purifi-2x400w-4-ohm-p-14557.html

Audiophnics new amp:

View attachment 68322


Kaluga

View attachment 68323

One of the two has both poor thermal management and poor cable management.

 

[maxxevv]

Strange that they opted for a deep rather than a wide configuration.

For a lot of people, its way harder to find a suitable perch for a deep component than a wide one.

 

[kaka89]

One of the two has both poor thermal management and poor cable management.

I don't think cable wiring is that different beside the main power wire is running through the center in the audiophonics unit. It probably can be moved if the cable is long enough. The overall layout looks quite similar.

Not sure how thermal management can be improved tho, could you suggest?

Strange that they opted for a deep rather than a wide configuration.

For a lot of people, its way harder to find a suitable perch for a deep component than a wide one.

They actually have both: https://www.audiophonics.fr/en/powe...ass-d-stereo-purifi-2x400w-4-ohm-p-14393.html

 

[boXem]

I don't think cable wiring is that different beside the main power wire is running through the center in the audiophonics unit. It probably can be moved if the cable is long enough. The overall layout looks quite similar.

Not sure how thermal management can be improved tho, could you suggest?

Rotating the SMPS by 180 degrees would improve a lot of things for cabling.
Amplifiers are trapped in hot air. I don't see anything to be done without heavy modifications.

 

[maxxevv]

They actually have both: https://www.audiophonics.fr/en/powe...ass-d-stereo-purifi-2x400w-4-ohm-p-14393.html

Did you actually look at the dimensions of the this and compare to the previous one ? This is just 40mm shallower than the previous one and more than twice as wide ! 190mm x 359mm x 78mm versus 413 x 322 x 60mm

 

[kaka89]

Did you actually look at the dimensions of the this and compare to the previous one ? This is just 40mm shallower than the previous one and more than twice as wide ! 190mm x 359mm x 78mm versus 413 x 322 x 60mm

Thought you were just complaining the non-standard size, but sure I get what you mean.
Good to have extra option for customer either way.

 

[barrows]

Any of you know whether J5 on the SMPS1200 can also supply regulated voltage? In the SMPS1200 documentation it doesn't explicitly state that it does, and that it only supplies regulated voltage through J4. I need regulated voltage as I'll be using a Neurochrome buffer board.

Also, will any old 10awg copper wire work for connecting binding posts to the board? Or do I need fairy dust wire?

I wouldl strongly recommend adding some very good voltage regulators to the Neurochrome boards (Tom has provided for doing this). The regulators on the Hypex SMPS are rather poor at high frequency PSRR, and this why the Purifi Eval board has discrete voltage regulators onboard, as does the NC-400, and many other Hypex modules. A lot of noise from the SMPS will otherwise pass through to the input stage and the modulator stage of the amplifiers; I am sure Mr. Putzeys has added these high quality discrete voltage regulators for a good reason.

 

[starfly]

I wouldl strongly recommend adding some very good voltage regulators to the Neurochrome boards (Tom has provided for doing this). The regulators on the Hypex SMPS are rather poor at high frequency PSRR, and this why the Purifi Eval board has discrete voltage regulators onboard, as does the NC-400, and many other Hypex modules. A lot of noise from the SMPS will otherwise pass through to the input stage and the modulator stage of the amplifiers; I am sure Mr. Putzeys has added these high quality discrete voltage regulators for a good reason.

This being ASR, do you have evidence for your claim that the Hypex SMPS regulators are poor at high frequency PSRR?

 

[barrows]

This is a well known quality of the rather long in the tooth 78xx and 79xx parts, and is why Bruno Putzeys went the trouble of designing the discrete regulator circuits used in the HrX Hypex regulators and the discrete regulators used on the Purifi Eval board.
I do not need to look up the data sheets on the 7912 and 7812 regulators to know this, but you are welcome to.
There is no mischief here, nor "audio magic" PSRR and PSSR at different frequencies are well known and understood properties.

 

[starfly]

This is a well known quality of the rather long in the tooth 78xx and 79xx parts, and is why Bruno Putzeys went the trouble of designing the discrete regulator circuits used in the HrX Hypex regulators and the discrete regulators used on the Purifi Eval board.
I do not need to look up the data sheets on the 7912 and 7812 regulators to know this, but you are welcome to.
There is no mischief here, nor "audio magic" PSRR and PSSR at different frequencies are well known and understood properties.

Thanks, I'll need to look into that. Any recommendations on good voltage regulators in case I go that route? The 7912/7812 good enough?

 

[barrows]

Thanks, I'll need to look into that. Any recommendations on good voltage regulators in case I go that route? The 7912/7812 good enough?

The neurochrom boards offer onboard voltage regulator adapters (optional) which accept the Hypex regulators, which are probably the easiest no-brainer type choice for high performance, as they were designed specifically for this use on the Hypex class D modules:

https://www.diyclassd.com/product/hnr12/153

Otherwise you would probably want to do some research. Typically monolithic regulators do not have the best PSRR at high frequencies, but there are a lot of choices out there. As Tom makes specific adapter boards suited to mounting the Hypex regulators, i would just go with them if it was me.

 

[starfly]

The neurochrom boards offer onboard voltage regulator adapters (optional) which accept the Hypex regulators, which are probably the easiest no-brainer type choice for high performance, as they were designed specifically for this use on the Hypex class D modules:

https://www.diyclassd.com/product/hnr12/153

Otherwise you would probably want to do some research. Typically monolithic regulators do not have the best PSRR at high frequencies, but there are a lot of choices out there. As Tom makes specific adapter boards suited to mounting the Hypex regulators, i would just go with them if it was me.

Tom also has these pre-assembled boards that plug right into his input buffer: https://neurochrome.com/products/vo...pex-nc500-input-buffer?variant=31750441795654

These use the 7912/7812 opamps. Would that be an easy go-to option?

 

[Digital Mastering System]

Thanks, I'll need to look into that. Any recommendations on good voltage regulators in case I go that route? The 7912/7812 good enough?

These LT3045/94 based LDO regulators are very good: https://www.aliexpress.com/item/4000559638704.html?spm=a2g0s.9042311.0.0.26304c4dfatL7K
I have used them successfully in a preamp rebuild. The documentation isn't great, but you can figure it out. In this case I would use a fixed external resistor to set the voltage.

 

[jae]

Any word on the Purifi powersupply?

 

[kukocz]

I do have some exciting news about cases for Purifi DIY build.

I have asked for the CAD drawing of the Modu shop GX288 case and sent it to Purifi. They are helping me adapt the necessary holes of the EVAL1 into the CAD drawing. When I get it I will send it back to Modu shop. After that, anyone can order a GX288 case from Modu shop and ask for it and it will be EVAL1 ready!
https://modushop.biz/site/index.php?route=product/product&path=25_291_293&product_id=444

Attached is the original CAD file that the Purifi team used for their demo unit, which is of very similar size to GX288 (photo by @Doug Schneider 's SoundStage! Network, they are going to release their Purifi review was released on June 1st).

Notice that the demo unit also has speakon holes on the chassis. Purifi said they would send both files, with and without speakon holes, so that the Modu shop customer can choose.

Stay tuned.

View attachment 65911

Anybody already ordered this enclosure from modushop?
I ask them for this modification and I received cad files with drawing of the back panel. I’m afraid that arrangement of the holes has been done improperly.
Their drawing shows that banana plugs are located 17 mm from bottom edge. Exactly the same distance as shown in purify documentation. But we have to take into consideration thickness of bottom cover (2mm at GX288?) on which EVAL1 will be placed. At the end Eval1 won’t fit into holes (or you bend pcb to fit it into right position )

 

[phoenixdogfan]

Anybody already ordered this enclosure from modushop?
I ask them for this modification and I received cad files with drawing of the back panel. I’m afraid that arrangement of the holes has been done improperly.
Their drawing shows that banana plugs are located 17 mm from bottom edge. Exactly the same distance as shown in purify documentation. But we have to take into consideration thickness of bottom cover (2mm at GX288?) on which EVAL1 will be placed. At the end Eval1 won’t fit into holes (or you bend pcb to fit it into right position )
View attachment 68759View attachment 68760

I think 17mm from bottom edge means 17mm from the internal bottom not the external bottom, in which case it should work just fine, but I would confirm that with them.

 

[beren777]

Anybody already ordered this enclosure from modushop?
I ask them for this modification and I received cad files with drawing of the back panel. I’m afraid that arrangement of the holes has been done improperly.
Their drawing shows that banana plugs are located 17 mm from bottom edge. Exactly the same distance as shown in purify documentation. But we have to take into consideration thickness of bottom cover (2mm at GX288?) on which EVAL1 will be placed. At the end Eval1 won’t fit into holes (or you bend pcb to fit it into right position )
View attachment 68759View attachment 68760

I am close to placing an order for one but I am also concerned about measurements, and also additional holes in the bottom plate for mounting the amp and smps. Please ask and let us know what the answer is. It'd definitely suck to order one and then have things not fit properly.

 

[Matias]

I don't know, but the Purifi team themselves applied the holes to this specific chassis. Are you sure it won't work?

 

[phoenixdogfan]

I am close to placing an order for one but I am also concerned about measurements, and also additional holes in the bottom plate for mounting the amp and smps. Please ask and let us know what the answer is. It'd definitely suck to order one and then have things not fit properly.

I'm trying to find a local shop in Nashville, TN, USA to fabricate a new back end and matching bottom holes in a Ghent 300 mm wide chasis originally intended for a dual NC 400 Hypex build and I'm having similar anxiety attacks about this very problem.