VTV Purifi Amplifier With SIL 994EnH-Ticha Pro Buffer Review

[Gorgonzola]

I have a VTV amp similar to the one Amir tested except with the Sparkos SS3602 op amp. The "sound" is quite satisfactory as I hear it.

That said, I thank Mathis for his comments regarding the lack of AC shielding since my VTV is the same -- I would like to know what can be done to improve the shielding. I note that VTV apparently includes an EMI/RFI filter on the mains receptacle though I've heard is said that this unnecessary.

I see that VTV has a new case or case option and I like it rather better than the Ghentaudio-sourced, (apparently), case that I have.

 

[restorer-john]

There we have it, the difference between product engineering and stuffing components into a box and calling it a day.

The thing has a gain stage up front to make the Purifi module compatible with normal levels. You're never going to get gain without some noise and degradation. And 2dB at that level is absolutely nothing. I think they did really well considering. I think that is what you are saying too?

I will have to run this on Purifi reference at some point to see how it did. I am thinking the buffer is messing this up right now.

And the measurement bandwidth. It is really a whole lot worse for HF, especially the 15kHz, we're losing harmonics.

 

[beren777]

Very curious to see the power vs distortion chart for a Purifi amp that is just a SMPS1200A400 + Purifi EVAL1.

 

[peng]

A bit off topic, but it's just funny to see how long Benchmark holds a visually distinct lead in the SINAD chart over other power amps. Half decade now, and still nothing in sight..

@JohnYang1997 You guys still have your sights set on that crown?

Lol btw, what is that panther

Good idea, has @JohnYang1997 ever hinted whether the likes of Topping would be working on a <$1,000 (or even $1,500) 100-200 W (truly 4 ohm capable) WPC power amp that can dethrone or at least come close in specs and measurements of the Benchmark AHB2?

 

[abdo123]

The thing has a gain stage up front to make the Purifi module compatible with normal levels. You're never going to get gain without some noise and degradation. And 2dB at that level is absolutely nothing. I think they did really well considering. I think that is what you are saying too?

it's literally worse than the evaluation board.

 

[JohnYang1997]

A bit off topic, but it's just funny to see how long Benchmark holds a visually distinct lead in the SINAD chart over other power amps. Half decade now, and still nothing in sight..

@JohnYang1997 You guys still have your sights set on that crown?

Lol btw, what is that panther

Working on it, slow yet steadily.

 

[Feyire]

Working on it, slow yet steadily.

Don't forget these important items as well:

• Variable gain
• 12V trigger

 

[VintageFlanker]

I imagine you'd have a hard time hearing much difference between any of the Hypex and Purifi amps clustered at the top of the list

Sure. As far as I'm concerned, I didn't hear much of a difference (if any) between Purifi and Ncore amps I tested.

However, I think the NC400 is significantly cheaper than the Purfi modules, which would make it the best value for money - possibly

Possibly if OEM or DIY. Still, @Audiophonics does sell both assembled NC400 and 1ET400A amps at literally the same price (and even cheaper for the Purifi in a smaller case).

 

[Matias]

That said, I thank Mathis for is comments recording the lack of AC shielding since my VTV is the same -- I would like to know what can be done to improve the shielding. I note that VTV apparently includes an EMI/RFI filter on the mains receptacle though I've heard is said that this unnecessary.

The EMI/RFI filter removes noise way up in the kHz and more. The noise measured in the amplifier output is more 60 Hz and its harmonics.

I am no expert in this but I would try to get teflon tube and pass the black and white AC wires in it? I am open for suggestions from the DIY members.

 

[Count Arthur]

Sure. As far as I'm concerned, I didn't hear much of a difference (if any) between Purifi and Ncore amps I tested.

Possibly if OEM or DIY. Still, @Audiophonics does sell both assembled NC400 and 1ET400A amps at literally the same price (and even cheaper for the Purifi in a smaller case).

I see Audiophonics now offer both a mono NC400 at €699 and a mono Purifi at €749, so very similar prices. I was looking a while a back, a year or so ago, and I don't think there were as many options for the Purifi amps. I specifically wanted 2 mono amps and something more compact than the large Hypex UCD700 mono amps I had, so that I could use long XLR cables and short speaker cables and hide the amps away behind the speakers.

In the end I went in a different direction and replaced both the amps and my speakers with active monitors, so no separate amps or speaker cables at all.

 

[trl]

A bit off topic, but it's just funny to see how long Benchmark holds a visually distinct lead in the SINAD chart over other power amps. Half decade now, and still nothing in sight..

@JohnYang1997 You guys still have your sights set on that crown?

Lol btw, what is that panther

Most amps have an input sensitivity of 1.2V RMS (old designs from the '80's had 0.7V RMS) while AHB2 has 2V RMS, so it's clear who's the winner in terms of background noise.

I'm sure John will bring something close enough to AHB2 to the market soon.

 

[peng]

Working on it, slow yet steadily.

Will it be ready within say one year? Please include a separate buffer with gain as the Purifi and Hypex modules have less than 26 dB gain if I remember right, so AVR owners can use the amps too without worrying about if the 1.2 to 2 V pre out can drive those amps to their rated output.

 

[abdo123]

Most amps have an input sensitivity of 1.2V RMS (old designs from the '80's had 0.7V RMS) while AHB2 has 2V RMS, so it's clear who's the winner in terms of background noise.

I'm sure John will bring something close enough to AHB2 to the market soon.

The S/N ratio test is done in abscence of a DAC's output noise. so the input sensitivity doesn't matter at all in that case.

 

[trl]

Input stage has a lower noise on AHB2 due to the lower internal gain.

 

[Rick Sykora]

The EMI/RFI filter removes noise way up in the kHz and more. The noise measured in the amplifier output is more 60 Hz and its harmonics.

I am no expert in this but I would try to get teflon tube and pass the black and white AC wires in it? I am open for suggestions from the DIY members.

I think you nailed it with the lack of any true testing to catch problems before he ships. It is nowhere close to an AP, but have eliminated and/or improved my builds using a QuantAsylum QA401. It is discontinued but the QA402 is only $500.

Have been pretty surprised how slight wiring differences can make a significant improvement to lower noise in an amplifier.

 

[abdo123]

Input stage has a lower noise on AHB2 due to the lower internal gain.

Without an input stage the Purifi has an input sensitivity of 10 Vrms, according to your logic it has the lowest noise, but it does not.

 

[trl]

I'm not sure we're on the same page here, sorry.

 

[Phorize]

The thing has a gain stage up front to make the Purifi module compatible with normal levels. You're never going to get gain without some noise and degradation. And 2dB at that level is absolutely nothing. I think they did really well considering. I think that is what you are saying too?



And the measurement bandwidth. It is really a whole lot worse for HF, especially the 15kHz, we're losing harmonics.

I can see I was ambiguous. I was saying, perhaps too harshly in retrospect, that they don’t appear to have validated the design before release. Obviously we aren’t talking about anything audible here, but it’s a shame to start with such a well engineered power stage and go backwards. Pedantic I know given the end result is still very good.

 

[abdo123]

I'm not sure we're on the same page here, sorry.

Purifi @ 12.75 dB gain (no input stage)

Benchmark @ 9.2 dB gain

I apologize I was mistaken, apparently Amir measures amplifiers with the lowest gain they possibly have, i thought the ABH2 had much higher gain.

The Purifi and ABH2 have the same performance realistically.

 

[TimoJ]

I note that VTV apparently includes an EMI/RFI filter on the mains receptacle though I've heard is said that this unnecessary.

It actually is recommended (by Purifi designer) not to use filtered AC-input. It may partially cause that 60Hz issue.