DIY Purifi Amp builds

[TimoJ]

I wondering if I use just one SMPS1200A400 and wire EVAL1 and one EVAL2 to it i.e. 3 channel amp, would there be problems? Or should I forget that and use SMPS600N400 (or SMPS400A400) for the EVAL2?

 

[JimB]

I wondering if I use just one SMPS1200A400 and wire EVAL1 and one EVAL2 to it i.e. 3 channel amp, would there be problems? Or should I forget that and use SMPS600N400 (or SMPS400A400) for the EVAL2?

Personally, I would consider your first suggestion, if cosmetics of the back panel won't offend you. It would certainly cost less than three EVAL2s and performance would be the same. Adding an SMPS600N400 for the EVAL2 would support maximum output, into low impedance loads, from all channels, simultaneously. A single SMPS1200A400 for three channels will not do that, but it would be adequate for my needs (higher impedances and lower volumes), while still having good peak power.

 

[TimoJ]

Personally, I would consider your first suggestion, if cosmetics of the back panel won't offend you. It would certainly cost less than three EVAL2s and performance would be the same. Adding an SMPS600N400 for the EVAL2 would support maximum output, into low impedance loads, from all channels, simultaneously. A single SMPS1200A400 for three channels will not do that, but it would be adequate for my needs (higher impedances and lower volumes), while still having good peak power.

I already have build a Purifi amp with EVAL1, so I would need just one EVAL2 and a new case. I'm using low volume with sensitive speakers, so losing some maximum simultaneous output won't be a problem. I could also position the SMPS1200A400 so that there is still space to install SMPS600N400 later.

 

[KarVi71]

Very nice! Are you driving it with the XLR output of the NAD C658 to the EVAL2/1ET400 combination with the buffer bypassed or not bypassed?

I'm running XLR to the Eval 2's and the buffer is not by-passed.

Havent tried the by-pass setting, and am not planing to.

I suspect the output voltage of the C658 would be insufficient (for max output) ...?

 

[Deleted member 65]

This is the only temp measurement I’ve seen on the Purifi. 50C idle, top open in a Nord case.

https://www.audiosciencereview.com/...-of-purifi-1et400a-amplifier.7984/post-237859

 

[JimB]

This is the only temp measurement I’ve seen on the Purifi. 50C idle, top open in a Nord case.

Of course, those hot component are air cooled and their temps will rise significantly with the top on. Any data on temps in your (super cooled) build?

 

[Deleted member 65]

Of course, those hot component are air cooled and their temps will rise significantly with the top on. Any data on temps in your (super cooled) build?

No temp measuremen here, I have no equipment to do temp measurements. Would be interesting to see temps when amp is under load.
Looking at purifi’s doc temp can be retrieved, see 5.4 I2C Register map, Reg 0x11 Temperature.

Edit: Seems only available in SW mode.

 

[JimB]

No temp measuremen here, I have no equipment to do temp measurements. Would be interesting to see temps when amp is under load.
Looking at purifi’s doc temp can be retrieved, see 5.4 I2C Register map, Reg 0x11 Temperature.

Edit: Seems only available in SW mode.

I worked with Ghent on the venting of their new case. I'll try to get a thermocouple measurement, with cover on, at moderate power, once I get and build mine.

 

[drfous]

Hiss out of the right channel.

So I got the kit together using the Ghent case and wiring harness. I have a strong hiss out of the right channel only with and without inputs connected. I've shielded all the cable running between boards and the mains line with copper tape. No effect.

I'm using the jumper for 120v usage.

No change to the gain jumpers. Using stock.

Any input would be appreciated.

Thx

 

[drfous]

The hiss is at 10-12 khz. About 52db with no inputs. No real change with inputs.

 

[MicroAudio]

The hiss is at 10-12 khz. About 52db with no inputs. No real change with inputs.

Check the + & - AUX rails and the VDR rail, see if they are good

Just to be sure

 

[drfous]

Check the + & - AUX rails and the VDR rail, see if they are good

Just to be sure

Thanks, I'll get the meter on it tomorrow. Wife's BDay today.

 

[MicroAudio]

Thanks, I'll get the meter on it tomorrow. Wife's BDay today.

Please post the results later

 

[JimB]

Hiss out of the right channel.

So I got the kit together using the Ghent case and wiring harness. I have a strong hiss out of the right channel only with and without inputs connected. I've shielded all the cable running between boards and the mains line with copper tape. No effect.

I'm using the jumper for 120v usage.

No change to the gain jumpers. Using stock.

Any input would be appreciated.

Thx

Hypex SMPS1200A400 used? Reaching for easy possibilities, are your jumpers J6 and J7 set to VAUX, not the default of VAUX,REG?

7.6 Jumper Setting (VAUX or VAUX,REG)
J6 and J7 are used to select the output voltage on pin J4.1 and J4.2.
• Position 1-2: Regulated VAUX,REG
• Position 2-3: Unregulated VAUX
When the connected amplifier is fitted with HxR voltage regulators, both jumpers need to be set to
unregulated Auxiliary voltages. VAUX,REG is the default jumper setting (J6, J7).

 

[drfous]

Yes Hypex 1200a400.

I have not looked at those jumpers. Will look at that.

 

[drfous]

Music, sweet music.

Thanks, Jim!!! It was the regulated/unregulated jumpers. I didn't pick that up reading through the materials.

We are in business.

 

[JimB]

Music, sweet music.

Thanks, Jim!!! It was the regulated/unregulated jumpers. I didn't pick that up reading through the materials.

We are in business.

Great. Of course, one could wonder why it was good for one channel but not the other - just differences in parts being operated out of spec.

 

[beren777]

Been waiting for this but now Eval2 is online

Poor Ghent, they just got the EVAL1 case released and now we will all start asking them for an EVAL2 case.

 

[yardbird]

I have the Purifi case and harness from Ghent, the eval 1 and the hypex 1200-400. The PS powers fine when not connected. When the power and Aux cable are connected, no LED on the PS and no power to the amp board. i did not wire the SpeakOns. Looking a the Aux cable, it appears to be wired backwards. Sent a note to Ghent to confim. Is anyone here able to confirm?
thanks,
Jeff

 

[drfous]

Great. Of course, one could wonder why it was good for one channel but not the other - just differences in parts being operated out of spec.

I had the same thought.

Thx again.