I would imagine that this would be a much more expensive proposition because it appears without schematics Benchmark goes for a very low impedance attenuator . So as a result they buffer before attenuation and then buffer after attenuation. This doubles the cost of a preamp in the amplification stages for most DIYers who will go source- attenutator then buffer to power amp. Then also, the LA4 also buffers each input as well. The Benchmark product is like a Ne Plus Ultra engineer's wet dream. Neurochrome is a wet dream for DIYers. ( all joking)
I also own an Benchmark AHB2 and LA4 for my main rig and am in the final stages of finishing my desktop preamp (based on this UB) for my office. I will be using an offshore remote passive 128 step resistive attenuator with the UB driving the MOD86.
Obviously, the UB is priced for the DIYer. However when I cost out the buffer stages that the LA4 uses , and they allow individual trimming on each input by relays and its settings retained in the FPGA!, it is not that bad a deal ( It is still a lot of money by DIY standards). I can now level match my RIAA input so switching to a DAC is not a huge leap in volume. For what one receives the Benchmark products are reasonably priced. That is absolutely not to take away from Tom's Neurochrome offering which offer the sensible DIYers a fantastic affordable value that takes them into real high end for a fraction of the cost.
I know Tom tries to steer people from his LM3886DR towards the MOD86 and I for one think he does not steer hard enough. What Tom offers in his Neurochrome amplification stages is staggering value though it does not look so on the surface. The last stage to move from middling DIY performance to true high end is not an easy leap, it is very hard. He provides an easy avenue at a very reasonable cost and it is engineered out properly by a guy who has experience and has talent. Not all engineers have the same talent.
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This maybe: Power Amp – Reference Line – Trinity l the perfect sound
Do note that they're measuring the THD Ratio and NOT the THD+N Ratio. And provide no other data. Oh, and didn't bother finishing their website (note the "Text" placeholder near the top). For 56400 EUR (67956 USD at the current exchange rate) I had expected more data and a more polished website. But then again, I'm a tough grader.
$68k... You could buy an Audi A3 with that and still have enough left over for a downpayment on a house.
Tom
Do note that they're measuring the THD Ratio and NOT the THD+N Ratio. And provide no other data. Oh, and didn't bother finishing their website (note the "Text" placeholder near the top). For 56400 EUR (67956 USD at the current exchange rate) I had expected more data and a more polished website. But then again, I'm a tough grader.
$68k... You could buy an Audi A3 with that and still have enough left over for a downpayment on a house.
Tom
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Apologies if this is a poorly worded post - but does the Universal Buffer help provide a more analogue sound?
The reason I ask, is that when I have a class a preamp in my system I find that music sounds slightly more organic and that the last bit of the DACs digital signature (Chord Qutest) is removed and music flows more naturally (a class A trait?). It is definitely 'helping' the DAC's output stage, and in a good way.
Does buffering with the Universal Buffer have a similar effect when placed in the chain?
The reason I ask, is that when I have a class a preamp in my system I find that music sounds slightly more organic and that the last bit of the DACs digital signature (Chord Qutest) is removed and music flows more naturally (a class A trait?). It is definitely 'helping' the DAC's output stage, and in a good way.
Does buffering with the Universal Buffer have a similar effect when placed in the chain?
The Universal Buffer provides a buffered (or amplified) version of the input. As documented in the measurements, it subtracts nothing and adds nothing. Or if it does, it's so far below what's audible (and measurable!) that it isn't worth even mentioning.
If you prefer a little fuzz in the sound, you're probably better off with one of Nelson Pass's JFET buffers. I think it was at BAF 2018 he gave away li'l buffer boards that allowed you to adjust the supply voltage on a simple JFET buffer, thereby starving the JFET of headroom and creating tons of low-order harmonic distortion. That could be the ticket. You can achieve something similar by adding a diode in parallel with the feedback resistor in an opamp stage.
Tom
If you prefer a little fuzz in the sound, you're probably better off with one of Nelson Pass's JFET buffers. I think it was at BAF 2018 he gave away li'l buffer boards that allowed you to adjust the supply voltage on a simple JFET buffer, thereby starving the JFET of headroom and creating tons of low-order harmonic distortion. That could be the ticket. You can achieve something similar by adding a diode in parallel with the feedback resistor in an opamp stage.
Tom
Yes, I think a single ended FET class A amplifier may give you the 2nd order harmonic distortion you are looking for. Nelson Pass mentions the pleasing musical sound of 1% second harmonic distortion.
You can do this with software: PKHarmonic VST Plugin - Audiophile Harmonics Generator | Distort documentation
It may also depend on the type of music you are listening to, since some types of music may sound better to Your ears with the second order harmonic distortion added.
https://www.firstwatt.com/pdf/art_h2.pdf
https://www.firstwatt.com/pdf/art_h2_v1.pdf
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I’m not asking this. The Universal Buffer doesn’t obviously cause technical issue as it’s really well engineered.
Apologies, but it’s difficult for me to describe.
For example, I tried a topping Pre90 which measures very well - but it did alter the sound. I would say there was more attack with the Pre90 in the chain and more impactful bass. However, it also made my qutest DAC sound less fleshed out, as if the frequency response had been pulled towards the reference i.e flat 20Hz to 20kHz. Pre90 was also perhaps slightly more aggressive in my setup. I find my impression interesting since both the qutest DAC and the Pre90 both essentially have flat FR when measured. The Pre90 did effectively add a more neutral tone even though it measures extremely well.
So, I don’t like fuzz, I like ‘accuracy’. But what adding my other preamp, the Master 9, into my chain does is positive. The transparency is the same as DAC direct to amp, but the act of ‘buffering’ through the Master 9 makes the music sound more natural and fuller, and with class A analogue flow. However, the Master 9 has way too much gain, a unity buffer in paper is better.
I guess I’m just trying to work out if this impact is. Class A and Class D can sound different, even if they measure the same at the same outputs.
Not to turn this into a "measurements vs perceived experience" thread, though I do think that's an incredibly fascinating topic, but there is the possibility that you're after something that's not characterized well by a distortion measurement.
I have heard from others that the Topping D90 "measures well, but..." Similarly, many praise my Purifi/Hypex Buffer even though the Purifi EVAL1 buffer measures well also. In that specific case, there are circuit differences that could account for the difference (the EVAL1 will deliver a single-ended output if used with a single-ended source whereas the Neurochome Purifi/Hypex Buffer will deliver a differential output, for example). But both measure well.
This is not to say that we should throw measurements out with the bathwater. The science is pretty clear that people generally find equipment that measures well to sound good in blind tests.
One of these days I would like to measure transient THD. So for example the change in THD when an amp goes from producing 10 mW to 10 W. It would be interesting if that could tease out some of this stuff. There could be other aspects of transient response at play too.
Tom
I have heard from others that the Topping D90 "measures well, but..." Similarly, many praise my Purifi/Hypex Buffer even though the Purifi EVAL1 buffer measures well also. In that specific case, there are circuit differences that could account for the difference (the EVAL1 will deliver a single-ended output if used with a single-ended source whereas the Neurochome Purifi/Hypex Buffer will deliver a differential output, for example). But both measure well.
This is not to say that we should throw measurements out with the bathwater. The science is pretty clear that people generally find equipment that measures well to sound good in blind tests.
One of these days I would like to measure transient THD. So for example the change in THD when an amp goes from producing 10 mW to 10 W. It would be interesting if that could tease out some of this stuff. There could be other aspects of transient response at play too.
Tom
Many people that consider it is better to have no feedback, also believe in the theory that TIM (Transient Intermodulation Distortion) is caused by excess feedback. There is an opposing view that it is due to not enough feedback (loop gain is too low).
There is a paper on Feedback. On page 11 is a review of TIM: https://linearaudio.net/sites/linearaudio.net/files/volume1bp.pdf
There is a paper on Feedback. On page 11 is a review of TIM: https://linearaudio.net/sites/linearaudio.net/files/volume1bp.pdf
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TIM was somewhat of a red herring -- what was going on was real but mis-attributed. The proposed solutions were also a bit over-done as simpler 'cures' exist. Walt Jung showed that it was really slew limiting in the power amp, especially its input stage. Bob Cordell also wrote a couple illuminating articles, for the old Audio mag, I believe.
That is actually not possible. There is always at least local feedback through regeneration. So for example a differential pair has emitter resistors to control the gain through regeneration. An output stage of a power amp is usually an emitter follower, which has enough local feedback to give it a gain of 1 (or just slightly less)
That would be interesting.
So, feedback after using PKHarmonic VST Plugin with foobar.
Qutest direct to power amp. The sound is slightly flatter without the added harmonics (H2@-90dB, H3@-100dB and H4@-110dB), but it’s not a huge difference to my ears. There is greater clarity without harmonic distortion and less hash. This is my preference.
The added harmonics seem to change my perception of loudness more than anything else - when the additional harmonics are added the sound is slightly fuller. However, I think my perception would be that a slight increase in volume, or mild equalising, would have a similar effect.
Master 9 just makes things ‘better’ when it’s in the chain - I’m still at a loss to identify how/what is occurring. I guess like Tom says there are so many different permutations with designs that even if they both measure well it could be any multitude of reasons why they sound different. Probably the only way to evaluate is to build and listen as this probably isn’t going to be determined with one silver ‘measurement’ bullet.