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post #211 of 771
Quote:
Originally Posted by Wenglish View Post

I don't have anything more sensitive to test with, maybe Ddoingwell has something? For practical use for me it's a non-issue, but it could be an issue for others.

Regarding the hiss, you may find that it's your source that's giving you that. If possible, try a few different sources, even try running the amp directly from the output on a CD player or off the record/pre-amp outs on an integrated amp. Barring that, try different volumes on the source you do have. I'm not getting any hiss though when the amp was newer, there were a few teeeny weeeeny crunchy bits coming off the volume pot as I turned it up/down that went away after about 12 hours. Also, my first amp developed a flaw and has been returned to the magnanimous Dave who has sent me a replacement before even waiting for the troubled amp to reach him. Seems that the over-heat protect in the chip was a bit trigger happy and the amp would shut itself off after about an hour of use. It would come back after a while but it was a pain so Dave offered to replace it immediately. Sound-wise, it's still magnificent and when the new one arrives, I'll comment more fully on the sound. I have a Meier and a PA2V2 as well as a Classic 10.0 pre-amp with headphone amp in the output stage for comparison.
post #212 of 771
There might be a bit of hiss on the TPA6120a2 Digital Volume amplifier.

I myself have noticed it.

I think it has something to do with the extreme speed and level of gain this chip has.

Controlling this chip is like controlling a nuclear reaction.

And I'm being quite serious.

The chip is so fast and responsive that it took allot of engineering just to get it stable.

At first the chip wanted to oscillate all the time and I suspect that is why you don't see too many amps using it.

It is just so hard to contain and control.

Now as to where the 'hiss' is coming from, I have yet to determine.

It may be that the chip is so sensitive it is picking up the noise of the resistors in the feedback loop...

Every amplifier has this type of feedback resistance but very few are capable of a 1300 V/μs Slew Rate!

Yes that's not an error.

It is capable of 1300 V/μs Slew Rate.

Try to find an op-amp or any amp for that matter that can do that.

And that makes that chip EXTREMEMLY HARD to master.

It could be picking up hiss from the source as well.

It is just very, very sensitive.

But to get performance like what it achieves, you have to have that kind of sensitivity.

Really, check out these specs:

http://focus.ti.com/lit/ds/symlink/tpa6120a2.pdf

Look at those numbers and try to find a chip that compares to that in any way.

If you find one let me know.

Keep in mind this hiss is very subtle and at the low end of the spectrum, like a low end pink noise, maybe coming from the universe....

EDIT: Just for the hell of it, I wanted to see if the models I have around here had "the hiss".

I had to first move to a very quiet room, that in itself was hard to find as there are fans and motors running all over this house... It is winter here after all...

After finding a reasonably quiet place, I just listened with nothing pluged in and I could not hear anything. Then I plugged in a 12 inch 3.5mm patch cord with the end open, and I could hear a slight, and I'm talking slight hiss, but I had to listen very hard to hear it.

Now to do a real test of this amplifiers internal noise, the input has to be shorted out and shorted out as close to the input as possible to create a "NULL".

I haven't done that, but I really see no need as with the cord simply unplugged I can't hear anything, so "NULLING" that would just be a waist of time for me. But I will build a "NULL" plug and try it one night when there is complete silence, perhaps camping in the woods on a freakishly quite night

But back to reality, you have to test for internal noise with a DEAD SHORT on the input. That is the only real way to see how much noise, if any an amplifier has.

Else it could be getting noise from a number of places, sources, cables, etc.

And it has to be a damn good "NULL", Gold plated and Super High Quality. Some metals create conduction noise, Gold is the quietest.

This amplifier is that sensitive...


hotaudio40
post #213 of 771
That generated a quick response.


Like I said, it's very, very hard to hear on the 2200s and that's only when turning the amp far past reasonable listening levels. I'm talking about the very, very upper end of the volume (as in the last few clicks on the knob). And even then, I have to be looking for it--I didn't notice it until I specifically went looking for it (in response to hearing the hiss of the RX700s).

At this very moment I just tried to see if I could hear it--and I can't over my laptop's exhaust fan. That's how quiet we're talking.

Using the exact same setup, just swapping the 2200s for the RX700s, I have hiss that's only audible when there's no music playing or when music is playing and the amp is set to such a low level (literally, 1-3 volume clicks over silent). And remember, the RX700s are $35 cans, so it could very well be their shoddy cable (and really, I want to lean towards this because of how hard it is to hear with the 2200s).

Overall it's a complete non-issue (I really want to emphasize that, as it does not in any way negatively affect music playback) for me/these two headphones. I would venture a guess that it would be a non-issue for pretty much every set of cans out there.

However, I know some IEMs are super sensitive and I'm just wondering how they would react.

Edit:
ddoingwell, nothing in terms of overheat for me, bummer to hear that. It's good to see, again, that Dave is standing behind his products.
post #214 of 771
Thinking of ordering one of the HOTUSB1 to work with an Acer Aspire One netbook I bought yesterday. Already have a couple of amps (portable & desktop) to use and this looks an affordable way of getting better sound from the netbook. Headphones will be Senn HD580 & Koss KSC75s (depending if at home or out & about).
post #215 of 771
Received the Hotaudio mkIV yesterday...shipping was only 7 days to Oregon. Dave shipped it out the same day I ordered it via a 2nd chance offer thru his ebay store.

I have about 7 hours on the dac so far, so burn in is still in progress, but I am happy so far. I ordered this product because of the buffered line out. I run my laptop to an amp 6 tripath amp that Derek H built for me (very nice little speaker amp). It likes speakers with effeiency of 90db or better. My homemade cabinets have tang bang 4 in. full range with 87db...so I wanted a bit of db push; which the mk IV acomplished nicely.

While I am no expert reviewer nor anyway near the likes of Skylab etc... I think this little dac will be fine. My former was an Echo indigo IO which I liked the sound but it just didnt push out enough current for my amp. Id say the mkIV is a bit warmer and perhaps a bit more forward

I have not been able to find kernal streaming on my computer yet, so havent tried that option. I do have asio drivers from my Echo so may try them.
post #216 of 771
Hello,

My HOTUSB1 arrived this morning: perfect packaging and quite fast shipping btw. It worked flawlessly and everything was ok, even if a quick look inside showed a construction far from, er, neat.

But it is fine: a quick comparo to my three references here showed it has less hiss than the M-Audio Transit and the (noisy) Yulong DAH1Mark, but just a tiny bit more than the Behringer UCA202 (almost totaly silent). This, using the really very sensitive Shure E500s (if you cannot hear hiss/hum with them, the thing is VERY silent!). The UCA202 is a bargain but the sound quality out if its hp jack is no exactly stellar, and as far as I have seen (well, heard) by now this HOTUSB1 is doing well.

More to come...
post #217 of 771

Using ASIO through a Hotaudio Mark IV

Quote:
Originally Posted by Danielj View Post
I do have asio drivers from my Echo so may try them.
I, too, own an Echo Indigo and the Mark IV. How would I go about trying to use the Echo's ASIO drivers with the Mark IV?
post #218 of 771

My second Mark IV has an additional jack!

Dave,
My second Mark IV arrived today. Unlike the first, it includes a second 3.5mm minijack--this one on the rear panel, beside the USB port! This rear minijack is neither shown nor mentioned in the user instructions that came with either Mark IV. Is it an Line In input? Or a third output (minijack 1, dual RCA, minijack 2)?
post #219 of 771
It is an extra output. I saw your post about the sub output and you having to unplug the sub to plug in your headphones so I took the liberty of adding an extra output.... I hope you don't mind....
post #220 of 771
Paul I dont know exactlyhow one would use the echo asio with the mk IV. I am hoping that by putting asio dll. in the foobar folder, that foobar will pick it up.. I too would like to hear if others have tried this, and to what effect

I was hoping that I could just use kernal streaming, but cant seem to find that as an option on my laptop
Dan
post #221 of 771
Quote:
Originally Posted by hotaudio40 View Post
It is an extra output. I saw your post about the sub output and you having to unplug the sub to plug in your headphones so I took the liberty of adding an extra output.... I hope you don't mind....
Talk about customer service!
post #222 of 771
Quote:
Originally Posted by hotaudio40 View Post
It is an extra output. I saw your post about the sub output and you having to unplug the sub to plug in your headphones so I took the liberty of adding an extra output.... I hope you don't mind....
Wow, that's hawt. I'm tempted to buy something from you just so I can experience such hawtness.
post #223 of 771
Quote:
Originally Posted by hotaudio40 View Post
It is an extra output. I saw your post about the sub output and you having to unplug the sub to plug in your headphones so I took the liberty of adding an extra output.... I hope you don't mind....
..due to these small, yet special attention Dave gives to his customers and their needs, ...off to eBay I go to place an order for one of these babies
post #224 of 771
Quote:
Originally Posted by josep View Post
Hello,

My HOTUSB1 arrived this morning: perfect packaging and quite fast shipping btw. It worked flawlessly and everything was ok, even if a quick look inside showed a construction far from, er, neat.

But it is fine: a quick comparo to my three references here showed it has less hiss than the M-Audio Transit and the (noisy) Yulong DAH1Mark, but just a tiny bit more than the Behringer UCA202 (almost totaly silent). This, using the really very sensitive Shure E500s (if you cannot hear hiss/hum with them, the thing is VERY silent!). The UCA202 is a bargain but the sound quality out if its hp jack is no exactly stellar, and as far as I have seen (well, heard) by now this HOTUSB1 is doing well.

More to come...
Sorry for auto-quote, but 12 hours later I re-done noise tests and things got same: HOTUSB1 has just a bit of hiss (only audible with the revealing Shure's).
More important is I made some SQ tests with just some familiar tracks (flac) and, to my ears and with the Shure as well as a pair of K701 (yes it does drive them to my listening level at least) the HOTUSB1 is the best DAC I have here to use with USB. A word that come to mind is "organic", but is is detailed and complete as well: I am quite happy with my purchase!

Regards
post #225 of 771

extra output

Quote:
Originally Posted by hotaudio40 View Post
It is an extra output. I saw your post about the sub output and you having to unplug the sub to plug in your headphones so I took the liberty of adding an extra output.... I hope you don't mind....
I LOVE IT! Thanks!
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