How shall I resolve my ambiguity towards my Purifi amp?

[Feanor]

A few weeks ago I received my stereo Purifi 1ET400A amp from VTV Amplifier; it has VTV's buffers with Sparkos SS3602 op amps. Unfortunately I have very ambiguous feelings for this amp.

My repro chain is FLAC or ALAC files, mostly 16/44.1 ==> Foobar2000 via WASAPI ==> Topping D90 DAC ==> [edit] Schiit Freya + preamp, mostly in Passive mode ==> Purifi amp ==> Zaph Audio ZRT 'Zaph Revelator Towers' ==> my ears.

(With apologies in advance to those who believe all amps sound the same), what I am hearing from the Purifi amp is:

• Amazing resolution, transparency, and dynamics, plus the most accurate instrument timbres I've ever heard;
• Absolutely no "warmth" or euphonic qualities; absolutely no tolerance for over-bright or otherwise second-rate recordings.

What's to be done? One option is to treat to another Hypex NCxxxMP model such as I had before the Purifi; it was broadly similar to the Purifi but less extreme in both good and bad qualities. Or something else ... but what?

 

[tmtomh]

A few weeks ago I received my stereo Purifi 1ET400A amp from VTV Amplifier; it has VTV's buffers with Sparkos SS3602 op amps. Unfortunately I have very ambiguous feelings for this amp.

My repro chain is FLAC or ALAC files, mostly 16/44.1 ==> Foobar2000 via WASAPI ==> Topping D90 DAC ==> Purifi amp ==> Zaph Audio ZRT 'Zaph Revelator Towers' ==> my ears.

(With apologies in advance to those who believe all amps sound the same), what I am hearing from the Purifi amp is:

• Amazing resolution, transparency, and dynamics, plus the most accurate instrument timbres I've ever heard;
• Absolutely no "warmth" or euphonic qualities; absolutely no tolerance for over-bright or otherwise second-rate recordings.

What's to be done? One option is to treat to another Hypex NCxxxMP model such as I had before the Purifi; it was broadly similar to the Purifi but less extreme in both good and bad qualities. Or something else ... but what?

If you want certain euphonic qualities, experiment with speaker placement or apply some kind of EQ.

 

[Feanor]

If you want certain euphonic qualities, experiment with speaker placement or apply some kind of EQ.

Thanks, yes. I've been using a gradual roll-off from flat at 1000 Hz to about -3.5 dB at 10 kHz. It does help but doesn't solve the issues. My speaker placement is optimal given the constraints of my listening room.

 

[Vini darko]

Maybe add a switchable tube buffer to take the edge off. Real Hifi music is like ultra HD porn , 99% ugly and horrifying
You have the classic "to much of a good thing" reviewers often mention.

 

[Inner Space]

Amazing resolution, transparency, and dynamics, plus the most accurate instrument timbres I've ever heard ... Absolutely no "warmth" or euphonic qualities; absolutely no tolerance for over-bright or otherwise second-rate recordings.

Your words above describe a technically excellent system working exactly as it should. But yeah, bright or bad recordings are going to be a pain. Use EQ to establish a pronounced left-to-right FR slope, with a pronounced hump between 100Hz - 300Hz for punch and warmth. Then over the upcoming weeks, back it all down little by little, until it feels right. You'll adapt to the new sound as you go, and probably you'll end up with a fairly subtle curve. But be happy - you're in the ideal situation - an organically pristine system that can be flavored to taste. Way better than the other way around.

 

[Feanor]

Your words above describe a technically excellent system working exactly as it should. But yeah, bright or bad recordings are going to be a pain. Use EQ to establish a pronounced left-to-right FR slope, with a pronounced hump between 100Hz - 300Hz for punch and warmth. Then over the upcoming weeks, back it all down little by little, until it feels right. You'll adapt to the new sound as you go, and probably you'll end up with a fairly subtle curve. But be happy - you're in the ideal situation - an organically pristine system that can be flavored to taste. Way better than the other way around.

I'll likely give this a try.

 

[Feanor]

Maybe add a switchable tube buffer to take the edge off. Real Hifi music is like ultra HD porn , 99% ugly and horrifying
You have the classic "to much of a good thing" reviewers often mention.

I forgot to mention my Schiit Freya + preamp. I have been using mostly 'Passive' mode, but 'Tube' mode does mitigate some of the Purifi's downside. Unfortunately tubes at the same time introduce their own artifacts that I don't like, such as the artificial "holographic" effect which tends to detract especially with Classical music.

 

[andreasmaaan]

Hi @Feanor, I have a suggestion for you. Instead of rolling off the high frequencies gradually to dry to take the edge off (which I suspect will at best do nothing, and at worst lead to potential dullness), I suggest you do something a little more surgical.

Your speakers are excellent (as all Zaph speakers are IME), but they do suffer from one slight flaw that's likely to give them a bit of a bright edge. That is, they use a 7" midwoofer crossed to a direct-radiating 1" tweeter, with no compensation for the directivity mismatch in the crossover design.

You can see this in the horizontal off-axis response posted on Zaph's website. I've highlighted the problem area:

I copied these responses into VituixCAD (loudspeaker design software):

I then EQ'd in a little dip in the problem region. This creates a balance between flat on-axis response, and smooth in-room response. My suggestion is for a -2dB EQ with a Q of 1.0 centred at 3500Hz, which results in the following:

The on-axis is now a little less flat, but the sound power and the in-room response should be a lot smoother.

(Ofc, it would be good to have more measurements to do this a bit more professionally, but based on the few measurements I have, that appears to be the best first try at solving the problem.)

Here are the filter settings in table form. You may want to play around with the freq., gain, and Q a little bit by ear:

Apologies in advance if this is not news to you / you've already tried similar...

 

[Vini darko]

I forgot to mention my Schiit Freya + preamp. I have been using mostly 'Passive' mode, but 'Tube' mode does mitigate some of the Purifi's downside. Unfortunately tubes at the same time introduce their own artifacts that I don't like, such as the artificial "holographic" effect which tends to detract especially with Classical music.

Lol I even considered suggesting the freya. Guess EQ is gonna be the easiest option. Or the wormhole of tube rolling

 

[Newk Yuler]

Maybe add a switchable tube buffer to take the edge off. Real Hifi music is like ultra HD porn , 99% ugly and horrifying
You have the classic "to much of a good thing" reviewers often mention.

That's how I went at it. I have a Topping D90/A90 combo connected by balanced jumpers and a Conrad Johnson tube line stage preamp in the RCA loop between them, and balanced cables to Audiophonics Purifi amps. I don't use the CJ a lot but it's there to easily color it by flipping of a couple toggles. These days it seemed proper to me to plan with SOTA clean components and use something to inject harmonic euphonics when desired.

 

[Feanor]

Hi @Feanor, I have a suggestion for you. Instead of rolling off the high frequencies gradually to dry to take the edge off (which I suspect will at best do nothing, and at worst lead to potential dullness), I suggest you do something a little more surgical.

Your speakers are excellent (as all Zaph speakers are IME), but they do suffer from one slight flaw that's likely to give them a bit of a bright edge. That is, they use a 7" midwoofer crossed to a direct-radiating 1" tweeter, with no compensation for the directivity mismatch in the crossover design.

You can see this in the horizontal off-axis response posted on Zaph's website. I've highlighted the problem area:

View attachment 99059

I copied these responses into VituixCAD (loudspeaker design software):

View attachment 99061

I then EQ'd in a little dip in the problem region. This creates a balance between flat on-axis response, and smooth in-room response. My suggestion is for a -2dB EQ with a Q of 1.0 centred at 3500Hz, which results in the following:

View attachment 99065

The on-axis is now a little less flat, but the sound power and the in-room response should be a lot smoother.

(Ofc, it would be good to have more measurements to do this a bit more professionally, but based on the few measurements I have, that appears to be the best first try at solving the problem.)

Here are the filter settings in table form. You may want to play around with the freq., gain, and Q a little bit by ear:

View attachment 99066


Apologies in advance if this is not news to you / you've already tried similar...

Very interesting indeed. I'll give that a try.

 

[andreasmaaan]

Very interesting indeed. I'll give that a try.

Hope it helps.

If not, fiddle a bit with the gain, frequency and Q. I suspect the optimal values lie somewhere between the following:

• Frequency: 3000 to 4000Hz
• Gain: -1.5dB to -4dB
• Q: 0.75 to 1.5 (depending on your software/hardware - irritatingly, there are multiple definitions of Q and not all DSPs adhere to the same one)

Without more comprehensive measurements, these are just guesstimates ofc. Good luck

 

[Blumlein 88]

Cannot believe no one has given you the right answer. That amp just needs 300 hrs to burn in. Then everything will be fine.

 

[watchnerd]

Cannot believe no one has given you the right answer. That amp just needs 300 hrs to burn in. Then everything will be fine.

Plus, need to make sure the cables are quality.

Amazon Basics RCA cables if the budget allows.

And burn those in, too.

 

[M00ndancer]

Cannot believe no one has given you the right answer. That amp just needs 300 hrs to burn in. Then everything will be fine.

Plus, need to make sure the cables are quality.

Amazon Basics RCA cables if the budget allows.

And burn those in, too.

Bad, bad @Blumlein 88 and @watchnerd!
No Christmas presents for you, I hope you like coal in your stockings.

 

[Feanor]

Cannot believe no one has given you the right answer. That amp just needs 300 hrs to burn in. Then everything will be fine.

I hope you're right

 

[Feanor]

Plus, need to make sure the cables are quality.

Amazon Basics RCA cables if the budget allows.

And burn those in, too.

In case anyone actually believes this, rest assured my cables are OK: Blue Jeans Belden 1800F with thousands of hours burn-in.

 

[Feanor]

Hope it helps.

If not, fiddle a bit with the gain, frequency and Q. I suspect the optimal values lie somewhere between the following:

• Frequency: 3000 to 4000Hz
• Gain: -1.5dB to -4dB
• Q: 0.75 to 1.5 (depending on your software/hardware - irritatingly, there are multiple definitions of Q and not all DSPs adhere to the same one)

Without more comprehensive measurements, these are just guesstimates ofc. Good luck

Thanks again.

So I tried this sort of; I'm not using a parametric equalizer, only Foobar's Graphic Equalizer. Seem my setting: note that I'm not trying to equalize the already fairly flat response of the Zaph ZRT's, however I'm attempting to gradually roll off the frequencies above 1 kHz to about -4 dB at 10 kHz.

I don't find that is mod has changed my Purifi qualms noticeably. Note that my listening is heavily furnished so I'd say a lot of reflections are damped relative to a livelier room. Also, I suppose that that's the reason my extreme highs are rolled off vs. the properly measured performance of the ZRTs.

It's also true that other amps I've compared aren't showing nearly the same effects as the Purifi.
.

 

[LightninBoy]

Couple questions for you, Feanor:

1. what amp did the Purifi replace? Was there any hint of your current issue with the old amp? Never mind this, you covered in the original post. Strange, I wouldn't think Hypex to Purifi would make much of a difference at all - for good or bad.
2. How loud do you listen? Do you notice that the harshness presents at higher levels?
3. Is is possible you are listening to the new purifi amp at a louder level than your old amp? I ask because clean power can sometimes encourage one to push the volume up a little and maybe that's highlighting some speaker or room issues.

This is an interesting situation because its the classic case where one could go deep into the subjectivist rabbit hole for a solution: tube preamps, cables, different amps, etc.

 

[watchnerd]

In case anyone actually believes this, rest assured my cables are OK: Blue Jeans Belden 1800F with thousands of hours burn-in.

Those must be old. 1800F doesn't seem to be offered any more.

All my Blue Jeans cables use different Belden stock numbers.

After those thousands of hours, don't forget to trickle-charge them annually to re-load the electron leakage.