Not helpful nor desirable.Good lord. Could you possibly be any more clueless? Please step away from your keyboard.
Not helpful nor desirable.Good lord. Could you possibly be any more clueless? Please step away from your keyboard.
Let's please be a bit more respectful to Mr Siau, he's large part of the engineering excellence for one of the most respected high performance audio electronics manufacturers in the world. He's definitely not the marketing guy, though seems to of drawn the short straw in having to deal with the online audio forums lol
http://www.aes.org/aes/john-siau
It's a absolute privilege to have him and indeed other knowledgeable industry folks participate here so please treat them with the utmost respect and courtesy.
Only if you know what I was talking about. It's sad that people like not to listen to the truth.Tricked implies deceit.
It's so much easier to be an expert critic than it is to fund, design, and deliver cutting edge products.
- Rich
That's a mix of different information from different perspective.I wish I understood this stuff. I heard it was common knowledge that using a 'normal' preamp circuit is better then using digital control. Something about digital control decreasing resolution for every step of volume you go down, I think. But I've also heard that properly implemented, a digital volume control can be indistinguishable and sound better, and actually improve the sound.
So correct me if I'm wrong, John does work for Benchmark?
Not helpful nor desirable.
No it was rude and obnoxious as were a bunch of others you wisely deleted previously.My comment was spot-on, and you contradict yourself.
DAC3 has 9.2uV noise at max volume. HPA4/LA4 has 1.9uV noise. HPA4/LA4 doesn't have the lowest noise possible. It's easily achievable to have less than 0.3uV noise.
For the first question, low noise input buffer then 1kohm pot then low noise output buffer is pretty good. In a headphone amplifier circuit it's basically already existing in a headphone amplifier so basically 1kohm pot can guarantee ultra low noise on the attenuation part. 10kohm pot isn't far off either still under 1uV. Low noise buffer can be easily made from high performance opamps which are really not expensive. With competent design in power supply and pcb, it will perform really well.I know this is is a little late in the conversation to ask, but how would you achieve lower output noise for an active pre-amplifier, let alone a headphone amplifying circuit?
And on that note, I'm not really convinced that the LA4 has superlative performance for a pre-amplifier. It's pretty impressive for its construction and design, and the stepped attenuator is fantastic, if not a little overkill, but it's possible to achieve an order of magnitude lower output noise in a pre-amplifier than what the LA4 can deliver.
I can't understand what is the source of all that noise in Benchmark's circuits. Coming back to headphone amplifiers, even though the HPA4 is a hair quieter than the Drop/THX 789 in gain 2 (zero gain) mode, it's still pretty noisy compared to to the IEM out of the RME ADI-2 DAC fs (the ADI-2 DAC fs has a significant 5-6 dB reduction in noise via the IEM output compared to the HPA4). Hell, even the JDS labs Atom is a little quieter than the HPA4! While the HPA4 may be the cleanest headphone amplifier on the market in the present in ters of absolute dynamic range, there's definitely room for improvement.
This is related to why I was wondering earlier in the thread if Benchmark is working on a lower-noise successor to the DAC3 (which has over 9 µV of output noise), perhaps using a newer D/A converter chip like the ES9038PRO that the Element X and Okto DAC8 are using (both of which outperform the DAC3 in SNR and SINAD). I'm also curious to see the upcoming Neurochrome HPA-1, the successor to the now discontinued HP-1, because that was another headphone amp that had tremendously low output noise. A headphone amp having <1 µV of output noise guarantees that even the most sensitive of headphones will have a noise floor so low that it is completely inaudible, enough to enjoy a fully audibly transparent headphone system in every use case.
Actually, seems like the THX-888 is slightly lower noise than the THX-788 (and therefore 789) - https://www.thx.com/assets/uploads/2018/02/AAA-Design-Specifications.jpgI believe it's published by thx that thx 888 will have higher noise than 789. You may find a chart of all those models and specs on google.
Yes, thank you for correcting me. I still do stand by my statement that I think it's possible to push that 2 µV lower. as We've seen in the newer DACs. I'm keeping my eyes peeled for the Okto DAC8 Stereo, heh.It may be unfair to speak about 9uV noise from dac3. It's because it has much higher output voltage. It would be 2uV ish or lower with 2V(unbal)/4V(bal) output level.
I'm also hoping for some competition with the HPA4Tom's new headphone amp is looking really promising. But I don't know much about the noise performance. You may ask him for more detail. I can trust him that it's very low distortion design that's for sure. And it's still in prototyping phase, there can be more changes. Let hope that it beats 789.
I am surprised there isn't 789 here. Two things to note here:Actually, seems like the THX-888 is slightly lower noise than the THX-788 (and therefore 789) - https://www.thx.com/assets/uploads/2018/02/AAA-Design-Specifications.jpg
Yes, thank you for correcting me. I still do stand by my statement that I think it's possible to push that 2 µV lower. as We've seen in the newer DACs. I'm keeping my eyes peeled for the Okto DAC8 Stereo, heh.
I'm also hoping for some competition with the HPA4
Thank you for correcting me again. I mistakenly thought the 789 was using 788 technology. If you ever find the noise specifications for the 789, please do share them!788 is completely different design from 789. Different chips are used. 789 and 888 on the other hand are very similar in design. 788 uses ad8397, 789 and 888 use opa564. 888 could possibly using something different but according to the photo i looked at the chip has same package as 564 and has mark of opaXXX looks like 564. So possibly different compensation techniques or values choices that makes the difference.
Thx 789 performance was published on the THX 789 massdrop/Drop page which is <1uV.Thank you for correcting me again. I mistakenly thought the 789 was using 788 technology. If you ever find the noise specifications for the 789, please do share them!
If you set the output level low on dac3 using jumpers. You will likely get same performance as LA4. Also depending on what power amplifier you use. You may not reach the limit of DAC3 in the first place. If assuming AHB2, you won't see performance improvement at all from LA4.A lot happened since my last post. Back to my original question, the DAC2 and 3 have internal passive jumpers that allow good matching with the rest of the system. I use 96db speakers I enjoy listening to music at low levels. I find that the DAC3 and 2 allow me to listen at those levels while being in a good range of the volume control.
Those passive jumpers are great and separate the Benchmark from many other DACs with digital volume controls that may perform comparably but in reality are les flexible and adaptable to the rest of the system.
I'd be also curious to see a comparison of the analog volume control of the DAC2 and 3 vs the HPA4 as I can imagine the stepped attenuator is far better than the analog controls of the DACs.
Today I got a chance to listen to the HPA4 in a dealer shop located in Hong Kong, however there is no LA4 or AHB2. It just has DAC3 hooked with HPA4.
Another issue is the remote control, as reported by others in this forum, it doesn't not support direct select input. You can only use Left/Right to select input. And the problem is the left/right not able select input 1. As input 1 is specially bonded to the DAC inputs, you have to select "USB/analog/... " Etc to switch to the input 1, and the same time it set the DAC input (if you have one).
This is a bit odd , and the design is really targeting for DAC3 user ...
The unit you tried was just configured for use with Benchmark DACs having older software. When the DAC has current software, you can scroll through all four inputs on the HPA4.