[Qonmus]

I just ordered the Bit Perfect DAC; I know this isn't as good as the DAC Straight. I am planning on adding an amp at a later date, but I thought for now the Bit Perfect would be nice. Assuming I add an external amp, would I notice a huge difference between the BPDAC and the DAC Straight?

 

[UTF]

It seems Fubar II also uses PCM2702. How will STRAIGHT compare to Fubar? They also cost about same.

Quote:

Originally Posted by CTechKid /img/forum/go_quote.gif IMO the DAC STRAIGHT is HOTAUDIO's best DAC, assuming of course you're feeding it into an amp. He's setup it up so the PCM2702 is totally raw in its output, and thus has no buffering or any kind of modification, and thats a considerable plus in my books.

 

[powerslave]

Sounds like your okay then.

dave

Quote:

Originally Posted by K_19 /img/forum/go_quote.gif Yeah, the Bithead does not have a separate line out, but I do remember reading the FAQ from Headroom that said while it doesn't have a separate line out, headphone out is just as good except for a little bit of distortion being possible. It does not mention anything about double amping. I don't listen to particularly loud volumes (my Bithead volume is set around 3/4 while my EF1 is around 10 o'clock) or anything, so is it safe to assume that it's relatively safe for now without risk of overloading? Edit: Here's what the FAQ says. 13.Q. Does the BitHead have a separate line out? A. No, it does not have a separate line out. You can use the headphone jack with confidence though; remember that, as a general rule, headphone amp outputs are just like good pre-amp outputs but typically just a bit noisier in terms of adding some background noise floor issues.

 

[K_19]

Thanks.

I purchased the DAC Straight earlier today... hopefully it will get here pretty quickly since I'm within Canada.

Looking forward to hearing the improvements!

 

[hotaudio40]

Hey thanks you guys

"DOUBLE AMPING EXPLAINED"

What you have to consider when amping is what you are doing.

Each "amp" has "gain" and gains multiply.... In fact amps are just gain devices...

So say AMP1 has an output of 2 Volts RMS as many DACs do...
And say AMP2 like say an EF1 has a gain of 3 (I'm just guessing)...

Then your maximum output voltage will be 2 Volts X 3 or 6 Volts RMS. (Assuming AMP2 is capable of an output of 6 Volts RMS)

Now depending on your headphones this may already be way too much like in some 16 Ohm IEMs.

That would be 6VoltsX6Volts/16Ohms or 2.25 Watts!!!

Most headphones can only handle 200mWatts MAX!!!

or .2 Watts!!!

So that would be a BIG ISSUE and you'd smoke those headphones fast at max volume.

IEMs can only handle way less then that, just a few milliWatts, like 20ish...


Example #2

You've got 32 Ohm headphones and have a DAC that puts out 2 Volts RMS.

Well in 99% of the cases... You're already done. (Assuming your DAC can drive 32 Ohm loads, some can't)

No amp needed as most 32 Ohm headphones are very efficient.

Example #3

You've got 300 Ohm headphones.
You've got a DAC or MP3 player putting out about .65 Volts RMS.

So your power into your 300 Ohm headphones is 1.4 milliWatts...

In some cases that is still enough as headphones are very efficient.

But the headphones say are rated for 200 mW of power.

Well to get 200 mW into 300 Ohm headphones you'd need about 8 Volts RMS.

So since you've got .65 Volts RMS coming out of your DAC or MP3 player,
and you need 8 Volts RMS to MAX out your 300 Ohm headphones ( and I mean max out...)

You'd need an amp with a gain of 8/.65 or 12....

Now not too many amps have gains of 12 , that is a lot from my experience...

So you MAY need to double amp that or may not depending on the amplifier.

Specs are almost always given with amplifiers...

And not ONLY would you need an amplifier with a gain of 12 ,

You'd also need to have an amp capable of putting out 8 Volts RMS.

8 Volts RMS translates roughly into 23 Volts Peak to Peak so your not going to get that out of your standard portable headphone amps, or out of most AC powered headphone amps.

But you CAN get high gain, high voltage amps for driving 300 Ohm loads, as that is what they are designed for....


For most applications I find 2 Volts RMS into headphones is PLEANTY of power.
For the other 20% you need about 4 Volts RMS

and for the final 5% you need the 8 Volts RMS.

So you have to consider these factors:

The impedance, efficiency, and maximum power of your headphones ( ie 32 Ohms, 110dB @ 1mW, 200mW max.)
The power, minimum load, and gain of your amplifier. ( ie 200mW, 16 Ohms, Gain of 3 )
The voltage going into your amplifier. ( output of DAC = 2 Volts RMS, output of MP3 player = .65 Volts RMS )

 

[Wenglish]

Quote:

Originally Posted by UTF /img/forum/go_quote.gif It seems Fubar II also uses PCM2702. How will STRAIGHT compare to Fubar? They also cost about same.

That's a good question, and not one that I can answer firsthand (as I don't have a Fubar II).

I do know that the Dac Straight was a noticeable step up over the USB1/2705 based dac. I also know that the DS is supposed to be the purest form of the 2702 you can get.

The Fubar II uses a roll-able OPA2604 on the analog output.

My armchair guess would be the DS would be more accurate or less prone to distortion when amped as it isn't being double amped (see above). On the flip side, the Fubar would put out more power and you could tailor the sound towards your phones even more (although the amp you're hooking the fubar up to might have rolling options).

 

[CTechKid]

Quote:

Originally Posted by Wenglish /img/forum/go_quote.gif That's a good question, and not one that I can answer firsthand (as I don't have a Fubar II). I do know that the Dac Straight was a noticeable step up over the USB1/2705 based dac. I also know that the DS is supposed to be the purest form of the 2702 you can get. The Fubar II uses a roll-able OPA2604 on the analog output. My armchair guess would be the DS would be more accurate or less prone to distortion when amped as it isn't being double amped (see above). On the flip side, the Fubar would put out more power and you could tailor the sound towards your phones even more (although the amp you're hooking the fubar up to might have rolling options).

I myself have not auditioned the FubarII either, but I have read issues regarding noise from the wallwart power feed. To get a totally clean sound Firestone recommends the 'Supplier' unit... an additional cost. Just something to keep in mind.

 

[UTF]

Make sure to share your impression. I may go with the DAC straight as well, if it is a positive experience to you.

Quote:

Originally Posted by K_19 /img/forum/go_quote.gif Thanks. I purchased the DAC Straight earlier today... hopefully it will get here pretty quickly since I'm within Canada. Looking forward to hearing the improvements!

 

[Mr_Tasty]

One minor thing of note about the DS. If your rig is set up to where the outputs will be facing the back you must keep in mind that WHITE is still RIGIHT and RED is still LEFT... only its now flipped.

I find this to be an odd design choice considering that most people will use the DAC with the output facing the back and the USB input as the front.

 

[K_19]

Quote:

Originally Posted by UTF /img/forum/go_quote.gif Make sure to share your impression. I may go with the DAC straight as well, if it is a positive experience to you.

Well, I just got the DAC straight in the mail today. My review here will be with the HD650's (it happened to be their turn in my rotation) and the EF-1 with Mullard tube so far.

My first thoughts with the unit is that it is VERY, very solidly made. It's constructed with what I'm assuming is aluminum, and is pretty much built like a tank. The overall size is pretty small, too. The connectors look like they are well built as well. My only gripe so far is the USB wire they bundle, which is WAY too short for my use. It looks like I'll have to invest in a longer one soon.

As for the sound... OH. MY. GOD. This thing definitely blows the Bithead away in terms of cleanness, clarity, and whatever. I know with my Bithead I was sort of double amping the thing since it doesn't have a separate line out, but the difference in clarity with the DAC straight has been nothing short of massive (and this is with the HD650 not quite burned in yet and with the "veil" not completely gone yet, which is scary. Damn, how clear will my K701 be?). I notice some soundstage boost as well, not in a wider sense but in a "3-D" sense. As for general SQ, I'm sure it's just letting EF-1 output the sound that it is supposed to as cleanly as possible, so it's doing its job 100% according to my expectations. Of course I haven't heard any higher-end DACs, but so far I see no reason to upgrade from the DAC straight whatsoever. I can't imagine anything would get much better than what it already gives out. Big kudos to hotaudio40 for creating such a fine product for excellent price.

I recommend it 100% to anyone looking for a line out DAC solution.

 

[UTF]

K_19, thanks for sharing your impression with the DAC straight!

 

[K_19]

NP. I now feel that the DAC Straight is the component that finally pushed my HD650/K701 to the "reference" quality. I did not know what I was missing with my old combination of Bithead and EF1 and they sounded good enough to me before, but now I am hearing what the true quality sound should be... I'm noticing things in recordings I never noticed before and getting instrument separation as I've never heard before. I know such descriptions usually applies with upgrades to newer/superior headphones, but in my particular case it was the DAC. I would have never realized how crucial the DAC component of the setup could be otherwise.

Liking it with the K701 as well. Again, this DAC definitely holds nothing back from the original source and enables my EF1 to output the sound as it is meant to fully... and the K701 truly do sound great with EF1 and the Mullard tubes with DAC Straight "freeing" them.

 

[UTF]

I have no complaint with EF1 for giving enough clarity, 3D effect and instrument seperation, but I feel EF1 lacks in power output or dynamic. Do you feel with a decent DAC like the straight ef1 improves in these aspects?

Quote:

Originally Posted by K_19 /img/forum/go_quote.gif NP. I now feel that the DAC Straight is the component that finally pushed my HD650/K701 to the "reference" quality. I did not know what I was missing with my old combination of Bithead and EF1 and they sounded good enough to me before, but now I am hearing what the true quality sound should be... I'm noticing things in recordings I never noticed before and getting instrument separation as I've never heard before. I know such descriptions usually applies with upgrades to newer/superior headphones, but in my particular case it was the DAC. I would have never realized how crucial the DAC component of the setup could be otherwise. Liking it with the K701 as well. Again, this DAC definitely holds nothing back from the original source and enables my EF1 to output the sound as it is meant to fully... and the K701 truly do sound great with EF1 and the Mullard tubes with DAC Straight "freeing" them.

 

[K_19]

Quote:

Originally Posted by UTF /img/forum/go_quote.gif I have no complaint with EF1 for giving enough clarity, 3D effect and instrument seperation, but I feel EF1 lacks in power output or dynamic. Do you feel with a decent DAC like the straight ef1 improves in these aspects?

I feel that while DAC straight probably doesn't have the strongest gain in the world, that the power difference it gives has been noticeable at least compared to the Bithead (and the DAC straight chip is supposed to be limit-free and max output anyways, right? That explains a lot). With K701 it can be almost too painful in that regard as already very forward high mids are pushed even further (had to go to mullard tubes to smooth that out...). But I feel it most with my HD650 which you may know demands plenty of power... with the Bithead it was only ho-hum average, but with the DAC straight it really gained a new life. Not only am I not passing the halfway mark in volume on the EF1, but energy difference is very much noticeable across all frequencies

Again, since I'm comparing this with an entry level DAC it will most likely not apply in the same way to you, but hopefully that helped with the perspective a little.

 

[Wenglish]

Quote:

Originally Posted by UTF /img/forum/go_quote.gif I have no complaint with EF1 for giving enough clarity, 3D effect and instrument seperation, but I feel EF1 lacks in power output or dynamic. Do you feel with a decent DAC like the straight ef1 improves in these aspects?

I used a Dac Straight with an EF1 and a bunch of tubes for a few months, before selling the EF1 in favor of a HA2 MKII SE.

I certainly found the DS to be a notable, audible upgrade over the 2705 based USB1. So yes, the 2702 based straight helped with extra detail and was a step up over my previous DAC.

However, paired with the EF1, I could never get a sound that was 100% satisfactory. It might have been synergy problems (I never really liked the EF1 with my Ultrasones and the modded W1000s played most of my library nicely, but not all) or it might have just been the amp. For me it wasn't a lack in power--I could barely turn the knob past channel imbalance range with the EF1. There was a lack of dynamics (compared to the Meier, at least) and there was a definite lack of speed. Mostly, I felt the EF1 had a generally flabby and uninteresting bottom end and, with certain tubes, it was just too polite for me.

So, yes, the DS helped the EF1 in my listening. However, the EF1 wasn't the answer for me--it sounds like it might be for you. The DS has a low power output, however, as it's entirely unbuffered. So if you're having power issues you might want to look into a buffered dac.