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VTV Purifi Amplifier Teardown(SIL 994EnH-Ticha Pro Opamp)

amirm

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I just reviewed the VTV Purifi amplifier with SIL 994EnH-Ticha input gain/buffer stage. This is a quick teardown of the unit.

Click on this image for larger size:

VTV Purifi Amplifier with Sonic Imagery Labs 994EnH-Ticha Pro Opamp Teardown.jpg


Take care of the obvious, the two larger modules are Hypex SMP1200 power supplies. In between them, the little boards to the left are the Purifi amplifier boards (with green PCB). To the right of them is their custom input buffer that allowed interchangeable opamps. While this board is made for a ton of flexibility, I am not happy with the long path lengths here. They can pick up noise and interference. The reference design from Purifi uses PCB mounted XLR connectors that provide a very short path to the input buffer IC. Not so here with those long cables (in comparison).

I also find the placement of the upper channel rather odd. Why not have it further up so that it can have a shorter path to the input and output?

The biggest safety issue I see is the mains wiring in black and white on the left. There is no hold down so they are touching the two heatsinks. Those heatsinks get hot. Depending on the temperature rating of the insulation of those wires, it could melt them over time and cause a dangerous short. Mechanical vibrations can also saw through the insulation with the sharp edge of the heatsink.

The top Molex connector is also used as a junction to feed the second power supply. I don't like that. I rather see a T upstream feeding both power supplies with equal length wiring (to be really anal about it :) ).

I am puzzled by selling an amp with those giant speaker biding posts but with skinny wires on the inside. I would shorten those wires and make them beefier.

There are also fine wires flapping in the wind for different power supply feeds for trigger circuit and such. They cross the main power supply wiring which could subject them to noise pick up.

Conclusions
Much of the heavy lifting is performed thankfully by the Hypex and Purifi modules. The assembler's job is to put these together in a safe and performant manner. I don't think that has been done here. Suggest a clean up path with input from community here to improve the design without much cost hit. As a minimum, the mains wiring needs to be tied down and away from heat sinks. Yes, chances of a short is one in a million. But do you want to be that one in the million?

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Vini darko

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Could be worse could be better. At least they have gone dual mono with the parts. The mains wires are a bit "how you going" you're right Amir.
Edit: with this lego type stuff I don't see much point in not going diy and monoblock. Mount the moduals to a copper plate so it can act as earth and ground plane. Then stuff them in a fancy wooden box with mains going in on the smps end and xlr/speakers at the other end. And put them on the floor right next to the speakers.
 
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sam_adams

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Can't tell from this pic; is that a flat washer or a spot in the case with no anodizing/paint where the AC ground is fastened to?

VTVPurifi.jpg


If it's just a flat washer with anodize/paint under it, that would be bad for a solid, low resistance ground point.
 

DWPress

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Wow, what a hot mess. VTV has been reviewed here on ASR before and while they may have taken to heart some of the free advice offered he's forgotten some of it.

This is why I enjoy building Lego creations with my son that incorporate motors and lights. Properly routing wires is the first consideration in any build.
 

dfuller

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Mains wiring is sloppy. I think it would also make more sense to have the power supplies closer together as well, further away from the amplifier modules on one side of the case.


Anyway, good bits... separate power supplies for each channel is nice to see. 990s are exceptionally clean op amps - better in most respects than most IC op amps - and certainly are not the cause of the noise.
 
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Matias

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I can't see any obvious interference from the AC wires to the amp modules. Anyone?
 

Koeitje

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Disappointing. Hopefully someone will make a linear PSU + Purifi combination.
And how is a linear PSU going to make it better?
 
OP
amirm

amirm

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OP
amirm

amirm

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Can't tell from this pic; is that a flat washer or a spot in the case with no anodizing/paint where the AC ground is fastened to?

View attachment 140327

If it's just a flat washer with anodize/paint under it, that would be bad for a solid, low resistance ground point.
I checked an unused one and it is conductive surface. As you I thought it was painted but it is not
 

Peternz

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It makes you wonder why. Did they do a crummy job on purpose? If they knew enough to put that amp together they would have known enough to do a better job, right?
 

mSpot

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