Benchmark HPA4 based on THX AAA Amplifier

[watchnerd]

WTH is THX AAA?

What kind of content uses it? Video games?

 

[Kyle / MrHeeHo]

I was at Canjam and asked the person at the Benchmark booth about it and they said that they included a balanced port because of the THX technology.

 

[watchnerd]

I was at Canjam and asked the person at the Benchmark booth about it and they said that they included a balanced port because of the THX technology.

Is THX topology balanced by default and required to be?

 

[Dimitri]

WTH is THX AAA?

What kind of content uses it? Video games?

It's slieces, it dices, it mops , it sweeps and weeps and does all sorts of other stuff we can't metnion here. It's great, you want it and you need it. What else do you need to know ?

More here (amazement awaits ) : https://www.triadsemi.com/thx-aaa-audio/

 

[Thomas savage]

It's slieces, it dices, it mops , it sweeps and weeps and does all sorts of other stuff we can't metnion here. It's great, you want it and you need it. What else do you need to know ?

More here (amazement awaits ) : https://www.triadsemi.com/thx-aaa-audio/

If it hoovers stairs im in , where do I sign?

 

[Kyle / MrHeeHo]

Is THX topology balanced by default and required to be?

I forgot to ask that since I was in a hurry, I'll ask that tomorrow.

 

[amirm]

A nice article from Benchmark on their stepped ladder volume control on the HPA4: https://benchmarkmedia.com/blogs/ap...il&utm_term=0_7c8c792ee5-b679e01ca0-198222653

Starting to make a bit of sense why it is so expensive.

 

[Dimitri]

A nice article from Benchmark on their stepped ladder volume control on the HPA4: https://benchmarkmedia.com/blogs/application_notes/benchmarks-256-step-relay-controlled-attenuator?utm_source=Benchmark's+Application+Notes&utm_campaign=b679e01ca0-EMAIL_app+note+11-20-17&utm_medium=email&utm_term=0_7c8c792ee5-b679e01ca0-198222653

Starting to make a bit of sense why it is so expensive.

It seems to me there were stuck between a rock and a hard place.
There aren't too many ways to have remote controlled volume control.
You can use a motorized pot. Which is potentially a mechanical nightmare Even if you find a great pot, you nee to Rube Goldberg the motor on it . Even if the pot is quiet, and tracks great you are still preceived as using a '90s solution.
You could skip the remote, but then you'll have to get up and adjust the volume ...of your headphone amplifier... (how long is that headphone cord anyway?)
Or you could use one of them digital controls but even if it was quiet enough, everyone else can do it.

So you have to come up with something else. And they did. And got a blog entry out of it to boot!

I'm getting the feeling it's overengineering for the purpose of differentiation.
Differentiation is good. It drives up the price!

It would be interesting to measure the "thing" with a plain ol' ALPS bypassing the FPGA driven relay 0.1% resistors contraption to see what difference it really makes.
I can come up with expensive experiments as long as I don't have to pay for them

 

[svart-hvitt]

I still don’t get it what’s the improvement over a 32 bit digital volume attenuation.

@amirm , how could the new analog volume attenuation be better than a 32 bit digital?

 

[amirm]

@amirm , how could the new analog volume attenuation be better than a 32 bit digital?

This is an amp only so no way to implement a digital volume control. They could put in ADC/DAC in there and they note that but obviously that would add distortion well above what the amp can do.

 

[Guermantes]

More here (amazement awaits ) : https://www.triadsemi.com/thx-aaa-audio/

So is that a Class AAA amplifier, then?

 

[svart-hvitt]

This is an amp only so no way to implement a digital volume control. They could put in ADC/DAC in there and they note that but obviously that would add distortion well above what the amp can do.

My point is, it needs to be fed an analog signal by a dac. And this dac has its own volume attenuation.

In other words, you end up with two volume knobs, attenuators in the system, and the one extra, analog attenuator doesn’t add anything (?) in terms of signal quality? A digital attenuator has probably around 135-140 dB of SNR etc at full volume, doesn’t it?

 

[watchnerd]

A nice article from Benchmark on their stepped ladder volume control on the HPA4: https://benchmarkmedia.com/blogs/application_notes/benchmarks-256-step-relay-controlled-attenuator?utm_source=Benchmark's+Application+Notes&utm_campaign=b679e01ca0-EMAIL_app+note+11-20-17&utm_medium=email&utm_term=0_7c8c792ee5-b679e01ca0-198222653

Starting to make a bit of sense why it is so expensive.

Well the Schiit Freya also has has a remote controlled stepped relay volume control....and it's kind of cheapish.

 

[Sythrix]

Does this mean Benchmark just changed their view on balanced headphones?

As was pointed out to me in another thread by mindbomb, nowhere does it say it has an actual headphone balanced output, only line level (though they certainly aren't calling attention to that fact). The headphone output is only specified once (no varying output power between balanced and single-ended), which means that the balanced headphone connection is probably single-ended, just a different way to connect to it.

Unless you can find specifications stating it's a balanced out elsewhere, it looks like they are sticking to their original story, which never precluded balanced line-level connections in their products. In fact they specifically mention that they are in favor of line-level balanced connections.

 

[RedCometZero]

As was pointed out to me in another thread by mindbomb, nowhere does it say it has an actual headphone balanced output, only line level (though they certainly aren't calling attention to that fact). The headphone output is only specified once (no varying output power between balanced and single-ended), which means that the balanced headphone connection is probably single-ended, just a different way to connect to it.

Unless you can find specifications stating it's a balanced out elsewhere, it looks like they are sticking to their original story, which never precluded balanced line-level connections in their products. In fact they specifically mention that they are in favor of line-level balanced connections.

It says here near the bottom. The specs given by Benchmark for power output are the THX 888 balanced specs. The SE specs for the THX 888 are likely lower, but they aren't available anywhere.

The reasons that Benchmark gave for not using balanced for driving headphones in their HPA2 was that it increased the number of parts with no improvement for specs. Now since THX's topology exists, the highest measurable performance is from a balanced amplifier. It makes sense that Benchmark would move to that, then, especially with this device which seems to be a "cost no object" statement piece.

Now, if you asked Benchmark if the headphone amplifier in the HPA4 sounds better than the HPA2 in the DAC2 and DAC3, my guess is they'd tell you no. They said basically the same thing about the DAC portion in their press release for the DAC3 (i.e. that there would likely be no audible difference between that and the DAC2, but that they were releasing a new model because improving technology allowed them to improve the measured performance and speed up the input switching.)

 

[Sythrix]

It says here near the bottom. The specs given by Benchmark for power output are the THX 888 balanced specs. The SE specs for the THX 888 are likely lower, but they aren't available anywhere.

The reasons that Benchmark gave for not using balanced for driving headphones in their HPA2 was that it increased the number of parts with no improvement for specs. Now since THX's topology exists, the highest measurable performance is from a balanced amplifier. It makes sense that Benchmark would move to that, then, especially with this device which seems to be a "cost no object" statement piece.

Now, if you asked Benchmark if the headphone amplifier in the HPA4 sounds better than the HPA2 in the DAC2 and DAC3, my guess is they'd tell you no. They said basically the same thing about the DAC portion in their press release for the DAC3 (i.e. that there would likely be no audible difference between that and the DAC2, but that they were releasing a new model because improving technology allowed them to improve the measured performance and speed up the input switching.)

Thanks for confirming. I originally thought that was the case but then was persuaded otherwise.

Pretty silly for a company like them to not include specs for both. They seem to obfuscate anything to do with balanced headphone output, not being clear about it in the official specs.

 

[RayDunzl]

Thanks for confirming. I originally thought that was the case but then was persuaded otherwise.

Pretty silly for a company like them to not include specs for both. They seem to obfuscate anything to do with balanced headphone output, not being clear about it in the official specs.

When the manual becomes available, it will probably be more specific.

https://benchmarkmedia.com/pages/manuals

 

[cjf]

I Pre-ordered one of these yesterday. Looking forward to trying it out as a Pre-amp replacement in my system. If it works as expected it will have saved me a bundle on the "High End" Pre I was intending to pickup.

In my view the benefit of using this device after a DAC like the DAC3 DX (which I own) is that it can address gain mismatch issues as well as digital VOL resolution related losses which can occur when not running the VOL knob at a high enough position when trying to use the DAC3 to directly drive a Non-Benchmark Amp.

In my setup while using the highest Analog Attenuator jumpers (-20db) there is still too much gain in the system (26db) to achieve a normal listening level. In my setup the volume knob of the DAC3 needs to sit at roughly 9'oclock for a normal listening level but at that position there is not enough voltage output yet to drive my amp to its full potential. Anything more than 10 o'clock on the VOL knob of the DAC3 and I start to approach Rave/Party Mode which is great if that is the mode you are trying to be in at all times.

Benchmark says the VOL knob should be at 12 o'clock or so with the -20db jumpers in place to achieve roughly 1.95v output. When I use the VOL knob at 9 o'clock the voltage is under what I need and its audibly recognizable. According to Pass Labs I should be feeding my Amp (XA60.8) at least 1.8vrms to take advantage of the Dr Jeckyl & Mr Hyde like behavior these XA Amps are capable of when they switch into A/AB Mode. The Spec sheet says only 1.1 vrms is needed for this Amp but that is based on only outputting the 60w which the Amp is advertised to supply into 8ohm. To take advantage of the additional output power (as seen in the Stereophile review) more than 1.1vrms is required.

Anyway, I'm looking forward to giving this unit a try. If its as transparent as I expect it to be, based on Benchmarks history of such, it will be a real shocker to the "High End" market. I was very impressed with the sound of the DAC3 in my system so I didn't hesitate to be an early adopter and try this HPA4 also.

 

[amirm]

It is great that you are purchasing it. Keep me in mind if you develop an itch for having it measured.

 

[RayDunzl]

In my setup the volume knob of the DAC3 needs to sit at roughly 9'oclock for a normal listening level but at that position there is not enough voltage output yet to drive my amp to its full potential.

You can't have it both ways, can you?