[anadin]

I've just ordered a Benchmark DAC1 PRE and can't wait for it to arrive.

.

 

[eweitzman]

Quote:

Originally Posted by EliasGwinn /img/forum/go_quote.gif Inherent drawbacks include: - Double output impedance - 50% reduction of damping factor - 100% increase in noise - +/-200% increase in distortion. Benefits include: - Increase gain - Increase slew rate

The damping factor decrease is just an effect of the increase in output impedance. What Elias doesn't tell you is how this will effect what you hear: the frequency response of the phones will change, as may the quality of the bass. What you will hear will sound different and be less accurate, but not necessarily better. If you want tone controls, use an equalizer so you know what the changes are.

- Eric

 

[Matias]

Elias,

A friend was about to buy a DAC1 and 2 retailers (B&H and Audio Revelation) said they are no longer authorized to sell outside the USA! What's going on??

 

[katalyst^]

Quote:

Originally Posted by Matias /img/forum/go_quote.gif Elias, A friend was about to buy a DAC1 and 2 retailers (B&H and Audio Revelation) said they are no longer authorized to sell outside the USA! What's going on??

Great

Now I have to either buy a second-hand one or pay a ridiculous 60-90% RRP premium to Australian resellers. There are reseller profit margins and then there is '****ing your customers in the ass'.

 

[poo]

Quote:

Originally Posted by katalyst^ /img/forum/go_quote.gif There are reseller profit margins and then there is '****ing your customers in the ass'.

Couldn't agree more. I imported mine from B&H not quite a year ago for the same reason. I guess Benchmark don't feel they can 'turn a blind eye' for the benifit of their end users... shame.

 

[anadin]

I am awaiting delivery of my DAC-1 Pre and have a couple of questions.

Is it worth the extra cost of upgrading the power cord and the USB cable, are the supplied cables of good quality that an upgrade isn't needed.

Many thanks.

 

[poo]

anadin, that's a real can of worms question that you will most likely get a range of answers to. Personally, I would suggest that the cables supplied are fine and your money would be much better spent on other things (like a bottle of scotch to enjoy when your DAC arrives).

I guess it depends whether you are into cables or not really - if better cables are going to give you warm fuzzies, go for it...

 

[dspargo]

Quote:

Originally Posted by EliasGwinn /img/forum/go_quote.gif No, the HPA-2 drives the headphone output only. The DAC1/USB/PRE does, in fact, have true-balanced outputs. These outputs can drive balanced headphones. However, I strongly advise against this configuration using any balanced headphone amplifier. I've written about this here and many other places, but I'll quickly summerize for you. Balanced headphone have many inherent drawbacks, and very little substantial benefits. Inherent drawbacks include: - Double output impedance - 50% reduction of damping factor - 100% increase in noise - +/-200% increase in distortion. Benefits include: - Increase gain - Increase slew rate These 'benefits' (increase in gain and slew rate) are hardly worth the major drawbacks. The gain and slew rate of the Benchmark's HPA-2 are far more then they need to be for the application, so increasing them won't gain any performance increase. I've addressed this here, but I'll recap for you. The output driver of the HPA-2 is the BUF634, a high-speed buffer amplifier capable of 250 mA output current and 2000 V/uS slew rate. Thanks, Elias

Elias,

What are the balanced outputs supposed to be used for?

I bought a HeadRoom Balanced Desktop Amp for my setup and this is a serious bummer. What do you recommend I do?

Thank you,
Don

 

[Mazz]

Quote:

Originally Posted by EliasGwinn /img/forum/go_quote.gif Balanced headphone have many inherent drawbacks, and very little substantial benefits. Inherent drawbacks include: - Double output impedance - 50% reduction of damping factor - 100% increase in noise - +/-200% increase in distortion. Benefits include: - Increase gain - Increase slew rate These 'benefits' (increase in gain and slew rate) are hardly worth the major drawbacks. The gain and slew rate of the Benchmark's HPA-2 are far more then they need to be for the application, so increasing them won't gain any performance increase.

I don't have any opinion on the matter, I don't recall too much of my electrical engineering courses, and I haven't had a serious listen to balanced headphones. But what I would like to know is whether these comparisons are on an apples-for-apples basis - i.e. driving the same pair of headphones to the same volume level, which presumably means to the same voltage differential (barring minor transient differences). It seems you'd get the double the slew rate from having two "identical" amplification circuits driving the signal in opposite directions. You'd have the same gain (by definition). You'd presumably have double some components of noise (IIRC some components are largely gain-independent), but maybe the same level of others (e.g. the component of noise present on the input gets amplified to the same level either way), and less of others (e.g. lower levels of noise induced on parts of the headphone cables - same principle as running long microphone cables to a mixer balanced rather than single-ended, but over a much shorter distance). I'm not sure why you get 200% increase (i.e. 3 times as much) increase in distortion, but perhaps it's in part due to the fact that it's really hard to get two absolutely identical amplification circuits.

And I'd also like to know how it sounds, because perhaps some or all of these effects are below the audible threshold and many people think it sounds better in various ways...but that takes a bunch of careful listening, and can be quite subjective, so I don't think this is the thread for it.

 

[pcf]

Ken Kessler gave the DAC1pre a glowing review in this month's Hifi news.
It gets a "Hi-finews outstanding product" tag. Here's how the artictle ends:

HI FI NEWS VERDICT
Not just good, but stupefyingly good. Benchmark's DAC1 pre provides you with
three highend components in one-DAC, headphone amplifier and preamplifier. In every mode, it excels. It sounds natural and authoritative, almost valve-like in the mid and treble. sublimely well made. It's an absolute joy to use. It does what it should, without drama. It is turly the Swiss Army Knige of hi fi.

 

[sonq]

Quote:

Originally Posted by pcf /img/forum/go_quote.gif Ken Kessler gave the DAC1pre a glowing review in this month's Hifi news. It gets a "Hi-finews outstanding product" tag. Here's how the artictle ends: HI FI NEWS VERDICT Not just good, but stupefyingly good. Benchmark's DAC1 pre provides you with three highend components in one-DAC, headphone amplifier and preamplifier. In every mode, it excels. It sounds natural and authoritative, almost valve-like in the mid and treble. sublimely well made. It's an absolute joy to use. It does what it should, without drama. It is turly the Swiss Army Knige of hi fi.

Is the Dac1 pre just the same as Dac1 but comes with addition of USB and preamp function? Used through the HP jack, is there any difference in sound quality between the 3 variants?

 

[Wavelength]

Elias,

Several companies offer balanced options for amplifiers and it basically means there is a seperate return (ground) for each phone.

The benefit of this can be seen in a current loop. If you have seperate grounds for each the amplifier the loop will consist of the amplifier it's coupling cap and series resistance the headphones and the resistance of the headphone cables.

If you use a common ground like most headphone amplifiers do then the grounds get summed and the effect both the amplifier circuits. Also many heaphone cables use the same geometry for each of the 3 conductors making the ground connection the weakest link.

Better headphones typically sum the ground connections at the jack but even then it does not sound as good as a totally sperate connection back to the amplifier ground.

Having worked with Arye for the last year and talking to Charlie Hansen about their amplifier technology I would have to say he would not agree with these statements:

Quote:

Inherent drawbacks include: - Double output impedance - 50% reduction of damping factor - 100% increase in noise - ±200% increase in distortion. Benefits include: - Increase gain - Increase slew rate

All of their power amplifiers (Product of the year for Stereophile) are balanced amplifiers.

In most cases wouldn't you say that if it is truely Balanced and the noise is the same for both channels, then wouldn't the noise be cancelled to only the inherent noise of the amplifier?

The same can be said for distortion as the summation of most of the second, third and so on would be removed.

But in general I guess it would be completely silly to say anything of the differences in specifications because the unit would be designed completely different from just putting two amplifiers together.

Thanks
Gordon

 

[EliasGwinn]

Quote:

Originally Posted by katalyst^ /img/forum/go_quote.gif Is there any difference between the DAC1 and DAC1 USB in terms of the quality of the headphone amp?

No, all DAC1's are built with the same HPA-2, and they all have the same quality.

However, the DAC1 USB and DAC1 PRE have additional features related to the headphone amp.

Specifically, the auto-mute function, which mutes the main outs when headphones are plugged in for seamless switching from loudspeakers to headphones (this feature can be disabled by the user.)

Another feature is the selectable gain range, which allows the user to customize the gain of the HPA-2 to suit their particular headphones' sensitivities. The DAC1 USB has two ranges, and the DAC1 PRE has 3 ranges.

Thanks,
Elias

 

[EliasGwinn]

Quote:

Originally Posted by luciyuspax /img/forum/go_quote.gif Only DAC1 and laptop will be plugged into the same strip.

You shouldn't have any hum problems with this setup at all.

Quote:

Originally Posted by luciyuspax /img/forum/go_quote.gif Also about those surge protectors with power filters(not the big powercenter models in a box), how do they behave with DAC1? I will either buy a monster HTS1000 or belkin pureav surge protector. I heard that they generally improve video quality of plasma TVs etc but that some amplifier really do not like them. Will they improve or decrease sound quality of DAC1 USB?

They won't affect the performance of the DAC1 whatsoever. The power supply is built to be impervious to fluctuations in power.

Thanks,
Elias

 

[Matias]

Quote:

Originally Posted by Matias /img/forum/go_quote.gif Elias, A friend was about to buy a DAC1 and 2 retailers (B&H and Audio Revelation) said they are no longer authorized to sell outside the USA! What's going on??

Elias,

Would you please confirm this? My friend is just about to order one, in other words, you are losing a customer because of this.