Benchmark ahb2 power amplifier

[Miska]

I hope more amps would come with adjustable gain - not just volume trim pot, but really a gain adjustment. Because this would allow running DAC straight to power amp and without having need for lot of attenuation. Because it is quite counterproductive to bash out 2V from DAC, then attenuate it to 100 mV in preamp and then amplify it again to 2V in power amp (or something like that)...

 

[Miska]

7 hours ago, barrows said:

@Miska, yeah agreed.  We have this problem because there are no real standards for home audio.  Couple that with the high variability of average levels on recordings (loudness wars...), and gain matching and needs get complicated.  In many home systems people are throwing away performance by having awkward gain structures, requiring lots of attenuation.

i DIY my DACs, and so can adjust output capability to suit the system at hand, but even then I find I have to have a fair bit of 'extra" gain to accommodate many audiophile recordings with low average levels and high dynamic range (Reference Recordings, Channel Classics, etc)-then I have t apply quite a bit more attenuation for contemporary pop, like Lorde or something.

 

Sure there are some differences and adjustment needs. But with suitable gain structure you can get very close to 0 dB attenuation with those highest quality recordings and get the best performance too. And still be safe with the louder lesser quality ones to rely on just small amount of digital adjustment for example from the player application.

 

Now I bet many audiophiles rarely if ever go to less than -20 dB attenuation. Same with my pre + power amps, quiet listening can be -50 dB volume and the loudest -20 dB. With loudspeakers that have way under 90 dB sensitivity.

 

Of the DACs best situation is with Holo Spring, since it puts notably lower output level with DSD inputs.

 

With headphone amps situation is much better, many HP-amps have switchable gain, so I can get better gain matching with headphones which is anyway what I mostly use for listening.

 

[Miska]

4 hours ago, Daverz said:

Just wanted to mention that Benchmark's new line-level preamp starts shipping tomorrow.  It's basically the HPA-4 without the headphone amp.

 

https://benchmarkmedia.com/products/benchmark-la4-line-amplifier

 

I would just get the HPA-4 instead, the price difference for leaving out the headphone power stage is relatively small...

 

[Miska]

5 hours ago, Kal Rubinson said:

Indeed, I did run three DAC3s into three AHB2s very successfully except for the inability to use the volume knobs.

 

But with that combination you probably get very good performance thanks to good gain matching and then it should be within bounds of safely relying on software digital volume...

 

[Miska]

23 minutes ago, sandyk said:

That's also why my own DIY Class A Preamp has a very modest gain of only 3.2 times

Very few people have the volume control /attenuator at even as high as half way much of the time.

 

Preamp with gain of 1 is more than enough. I'm not sure if my preamp has any gain. And then at least 10 dB off the typical power amp gain and then it starts to become useful... In many cases, having just 2x gain throughout the entire pipe would be enough.

 

[Miska]

1 hour ago, psjug said:

Got it.  The low gain means the source SNR is not compromised; i.e. source S is as high as reasonably possible.

But still some of us were wondering if the Benchmark numbers might be inflated because of the low gain in the amp.  So that is why I put up a copy of JA's description of his tests.

 

Even if it is "inflated", you still get the benefit in the end because you don't have the excess gain...

 

[Miska]

8 hours ago, Kal Rubinson said:

I was referring to a temporary situation but it reveals my personal preference for a physical knob control.  AFAIK, the only multichannel DACs that have a physical volume knob are the Merging (NADAC and Hapi) and the upcoming OKTO.  Do you know of any others?

 

If it doesn't need to have DSD support (well, I think OKTO doesn't do high rate DSD multichannel anyway), I think there are number of such around in pro-audio. Like RME UFX+, or pretty much anything you can control with ARC USB. And then Prism Titan and Prism Atlas. Then Apogee Control works with number of their products. Then Universal Audio Apollo x8 and Apollo x16. And then Focusrite Red 16Line. Probably there are many many others.

 

[Miska]

23 minutes ago, Kal Rubinson said:

I will look into those but there are other requirements. 6-8 channels, PCM/DSD, physical volume knob, wireless remote control.

 

I can control HQPlayer with wireless remote control, but your requirements are becoming complex enough that there's probably not much left. Rules out also Hapi (AFAIK it doesn't have wireless remote control). Focusrite can be controlled also with iPhone/iPad.

 

I personally don't want a DAC with digital volume control, because I'm not happy with the implementations. If a DAC has volume control, for me it must be analog, like motorized pot in Marantz, or even better a switched resistor ladder like in T+A (my preamp also has switched resistor ladder). For computers you can get all kinds of knobs, bells and whistles to control the software volume.

 

The remote controls I referred to in the earlier post are specifically ones with a knob, I assume that is also what you want with a remote control. There are quite a bunch of such for studios/mastering use. You can usually also switch function of the knob between volume/seek/whatever with simple press of a function key. A bit like my DSLR that has two programmable rotary controls and couple of programmable function buttons.

 

[Miska]

23 hours ago, Kal Rubinson said:

Is there a wireless RC volume control (knob or not) that will work with HQP? 

 

Since HQPlayer supports standard multimedia HID codes, there are number of options. I've used various HTPC remotes (usually these are sold as kit with a USB receiver and a remote control), and I think I also Apple's IR remote was working on Windows (BootCamp). So things like play/pause/stop/next/previous/volume up&down, etc work.

 

On macOS iTunes at least used to steal all the media keypresses, so there are some alternative keys there.