Is this a modern but flawed preamp

[wizons]

Would you consider a modern preamp (tube or SS) that is 0.5dB down at 15kHz and 1.0dB down at 20kHz as flawed? I am not going to mention the preamp I have in mind, but these are its specs.

Given that few people on the Wam will hear beyond 15kHz, does it matter if the amp is otherwise very good? Or perhaps such a roll-off at high frequencies might result in an overly 'warm' sound.

Obviously such specs are flawed in the 'Sergeian' sense, but if there is no discernible difference when listening and the amp's specs are ideal in other regards (eg, gain matching to power amp, number of inputs etc), does it matter?

 

[pmac]

If it sounds good, it IS good

FTM

;-)

 

[RobHolt]

Not flawed - just adding a tiny amount of flavour.I also don't believe that many people would detect 0.5dB @ 15 and not 1dB @ 20khz under blinded conditions.

+1

It might be noticeable to younger listeners (teens and below really) but it will likely pass unnoticed by most people.

Even when heard, the effect is going to be very slight - the tiniest loss of air and sparkle perhaps compared to flat.

To put this into some perspective, the HF levels as heard at the listening position >10khz will jump around by several dB just by slight movement of your head.

 

[anubisgrau]

that's still less than your average speaker roll off....

 

[wizons]

:? :?

that's still less than your average speaker roll off....

:? I thought the majority of loudspeakers these days had artificially rolled-up high frequency response, typically adding circa 6dB at around 15kHz to create the false impression of 'air' and soundstage.

 

[anubisgrau]

ah i've thought you have proper speakers....

 

[Tenson]

Certainly not +6dB at 15KHz, even for a bright speaker.

I'd hope for a pre-amp with flatter response than that, but if the other specs are very good then I think it was made that way on purpose to give a less hard and bright sound. I also wonder what the cause was in the test that highlighted it. Perhaps it is not really a response fault but a high output impedance problem which is a bit more annoying because it will vary the response with different equipment.

 

[wizons]

Certainly not +6dB at 15KHz, even for a bright speaker.I'd hope for a pre-amp with flatter response than that, but if the other specs are very good then I think it was made that way on purpose to give a less hard and bright sound. I also wonder what the cause was in the test that highlighted it. Perhaps it is not really a response fault but a high output impedance problem which is a bit more annoying because it will vary the response with different equipment.

OK, the preamp in question is the Icon Audio LA 5tx, which has output transformers, the input being buffered by valves so as to ensure that source impedance etc does not compromise the amp's performance. The specs are IA's own and do surprise me a little. It makes me wonder if the output transformers leave something to be desired.

 

[Tenson]

The output of the pre-amp is not buffered though, so the FR will likely vary depending on the load. In most cases it might be very minor but some tests will load anywhere from 600 Ohms to 100K Ohms. IMO it just isn't a technically good design as the THD spec is poor too, with nearly 0.2% at only 0.5V output. Yes I'd call it a modern flawed design. My Dac/Pre-amp has more like 0.0005% THD and the output is buffered plus it acts just like a transformer offering isolation from ground noise.

 

[wizons]

The output of the pre-amp is not buffered though, so the FR will likely vary depending on the load. In most cases it might be very minor but some tests will load anywhere from 600 Ohms to 100K Ohms. IMO it just isn't a technically good design as the THD spec is poor too, with nearly 0.2% at only 0.5V output. Yes I'd call it a modern flawed design. My Dac/Pre-amp has more like 0.0005% THD and the output is buffered plus it acts just like a transformer offering isolation from ground noise.

Thanks -very informative. It seems to me that a modern preamp should have better specs. What DAC/preamp are you using?

 

[craigmclellan]

Try it, if you like it, buy it.

 

[Tenson]

Thanks -very informative. It seems to me that a modern preamp should have better specs. What DAC/preamp are you using?

It's a modified DEQ2496 - http://behringermods.com/deq2496.html

 

[Rodney Gold]

The ideal response curve at listening position is uptilted in the bass and sloping down from 5-10k ... if you see a typical room/speaker response curve it looks like the bastard child of the Himalaya's , the alps and the grand canyon..I would not worry about the slight UHF droop..there is no real musical content there and if the pre sounds good to you - it is...

 

[banjoman]

I appreciate specs and measurements do matter, but for me it does come down to what I hear.

My Croft pre-power combo are the best sounding amps I've had in my system despite the poor measurements of the similarly designed Croft integrated in the Stereophile review. Sounds better than amps I've had with better measurements from the same reviewers. Also, I've found amps with lower power rating (like my old Sugden A21SE) sound better and more gripping than much higher powered amps like the Pathos Logos.

 

[JamPal]

Bats and young kids are the only ones that need to worry here I feel.

 

[wizons]

The ideal response curve at listening position is uptilted in the bass and sloping down from 5-10k ...

Interesting. I've often though that at a concert (I'm thinking of acoustic - no amplication, whatever the genre) a significant proportion of high frequency energy is probably dissipated in the hall. Many modern classical recordings seem to be recorded with a mix of close and 'distant' miking, resulting in a confusing mix of simultaneous near and far field perspectives, which is rarely like the concert hall experience. If this is correct I can see your comment makes sense in that some roll off at higher frequencies might produce a sound more akin to the live experience.

 

[Tenson]

I always find recordings sound dull compared to real life if the mics are placed at the same position as the listener at the event. The mics seem to need closer placement to get what you would 'think' you hear at the real event.