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Amplifier Bakeoff: Purifi Eval1, McIntosh MA252 & Benchmark AHB2

BrokenEnglishGuy

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Rounded off in a way that it lacks transients and lacks inner detail. Think if you put a slight, but significant downward slope in EQ and added a little low level barely perceptible noise to cover up the lower level details. Done right, you won't think it rolled off or noisy, but it sounds slow and unresolving.

In the old days the difference in a Shure MM cartridge and a good MC cartridge.
My 2c.


Many audiophiles perceive the speed incorrectly, many issues in the room, like enhancements in the sub bass region can destroy the image of transients and can mask the details
If there is some huge enhancement in a random frequency you are going to hear a lot of that distractive thing in that specific frequency, BUT NO AUDIOPHILE after a listening sesion are going to tell you something like '' hmm, i find a bump at 66hz, and my golden ears says it's around +3dB, also there is a cancelation around of -2dB at 100hz ''.
You are going to need a microphone.

No one after a listening sesion are going to tell you how much nulls and enhancements in a room you have, in fact going to listening in a store a speaker and judge the woofer is the most worthless thing.
 

peng

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Hello.

I own the audiophonics purifi eigentakt and later bought a benchmark ahb2.
My speakers are kef r3.

Some people here commented on the Kef r3 topic they find the kef r3 boring, including Amir. I reached the same conclusing and was not happy. I was shopping for new speakers. My purifi was driving the kef r3 at the time. But then I bought the benchmark ahb2. The Kef r3 changed completely. A lot more life and dynamics. My kef r3 became amazing.

So I am positive when I say the sound of the purifi is compressed in combination with the Kef R3. As far as I am concerned the purifi is an inferior product. I dont care how much people love Bruno, the purifi is crap.

The Kef are probably hard to drive and that explains why so many people find them boring. With the purifi they lacked dynamics, very slow sound. Funny thing is the benchmark claims 100W and the purifi 200W.

Based on its specs, it may not be easy to drive but also not that hard to drive when KEF recommended 15 - 180 W. This does not seem to be a power related issue based on my experience with many amps and speakers. If it is due to power (or current, more appropriately) deficiency related issue, the symptoms would have been quite different than what is being described and I think you probably would agree..

We can also look at ASR's measurements, and it did show a combination of impedance dip and moderate high phase angles in the narrow 35 to 45 Hz range, and also relatively low impedance (4 to 5 ohms) in the 100 - 300 Hz range. That's should still be an easy load for the Purifi amp.
If the Purifi amp is an "inferior product", or "crap" as you called it, other ASR members would have been complaining. I haven't seen such complaints from other ASR members, not from me for sure.

So my guess is that may be you have a defective amp, or something else is not right.

R3's specifications, pasted from KEF website:

Maximum output110dB
Amplifier power (recommended)15 - 180W
Nominal Impedance8Ω (min.3.2Ω)
Sensitivity (2.83V/1m)87dB
 

tedmingo

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Oh ... I don't know. I use an AHB2 and I play a stringed instrument. I have heard only one other Amp that had better clarity and detail than my Benchmark on stringed instruments, and it was a Single-Ended Class A from Pass Labs. But, hey ! this is all subjective.
 

DHT 845

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BrokenEnglishGuy

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Well, the '' dull '' sound for me it's the slope, just see how much stronger the bass is here
index.php

Even the Polk R100:
CEA2034%20--%20Polk%20R100.png

R3:
index.php




In real weal the slope looks like this (thanks Erin)

PIR%20vs%20MIR.png

But a ''neutral'' slope looks like this
Kii%20THREE%20In-Room%20Measurements%20vs%20Estimated%20In-Room%20Response.png
 
Last edited:

Newman

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Your graphs above are not all graphs of the same thing. What are you asking us to look at in all graphs? There is no one thing that is graphed in all of them.

Also, what is the claim you are making? That an overall 'dull' sonic balance is caused by an EBS-like shelf in the low bass? (but not sure which measurement does this shelf need to be visible in...)

cheers
 

Newman

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Of which response curve? There is no one measurement present in all 5 plots.
 

Newman

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Which of the 3 FR responses on the CEA2034 graphs? Sound Power?

And what is a 'weak' slope? You mean flat, or steep?
 

Larry B. Larabee

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Well, the '' dull '' sound for me it's the slope, just see how much stronger the bass is here
index.php

Even the Polk R100:
CEA2034%20--%20Polk%20R100.png

R3:
index.php




In real weal the slope looks like this (thanks Erin)

PIR%20vs%20MIR.png

But a ''neutral'' slope looks like this
Kii%20THREE%20In-Room%20Measurements%20vs%20Estimated%20In-Room%20Response.png




The performance of those speakers, according to the graphs shown, are quite similar. So similar in fact that any measurement shown for one speaker can be duplicated ( I bet within 0.5db) to another simply by relocating the microphone measuring position. Exactly in a way that if I had any one of them in my room I would simply change the speaker or listening position to make them sound virtually indistinguishable from one another.

L
 

BrokenEnglishGuy

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Which of the 3 FR responses on the CEA2034 graphs? Sound Power?

And what is a 'weak' slope? You mean flat, or steep?
1639261966766.png


Can you see the difference?

I put the R100 only for showing how weak the slope for R3 is, the R100 is a very small bookshelf.
 
Last edited:

Newman

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Sorry, I misread your "from 100Hz to 20Hz" as 100 to 20 kHz.

So you are confirming my original question: that your claim is that an overall 'dull' sonic balance is caused by an EBS-like shelf in the low bass.

Interesting.
 

BrokenEnglishGuy

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Sorry, I misread your "from 100Hz to 20Hz" as 100 to 20 kHz.

So you are confirming my original question: that your claim is that an overall 'dull' sonic balance is caused by an EBS-like shelf in the low bass.

Interesting.
I '' corrected '' the slope by adding a low shelf filter
For me sounds much more dynamic, natural and the sense of weight increased. I can't go back with the stock slope.
index.php
 

pogo

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On a few run of the mill speakers, I really couldn't tell much of a difference as they themselves just don't have the detail resolution of the S5 or the Magnepan LRS.
Have you also connected the Magnepan LRS to the benchmark as a counter test and if so, how were your impressions there?
 

pogo

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I '' corrected '' the slope by adding a low shelf filter
For me sounds much more dynamic, natural and the sense of weight increased.
But this should be the last option to improve the sound impression. In my case, for example, it was a higher DF that achieved the goal. I also had such a filter before, which definitely had a positive subjective effect. But the higher DF then showed even more details and I could reduce my DSP use a lot.
 
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