[gajira]

Quote:

Originally Posted by Ferbose As for DHA-3000, it uses 2SJ554 and 2SK2955 MODFETs in its output stage, according to this review: http://sound.zol.com.cn/22/225625.html. So, this it is an amp with a built-in DAC. Unfortunately, it has no analog input. It does come with a lot of DSP stuff though. Its DAC chip based on the "fluency" algorithm, which is popular in Japanese products, based on this link: http://www.wslab.risk.tsukuba.ac.jp/publications.html. So this is not a digital amp, not even class D.

I can't find 2SJ554 and 2SK2955 in my DHA3000.

The composition of DHA3000 is
AK4112BVF(DAI receiver)->SM5849BF(Asynchronus Sample Rate Converter)->FN1245(PWM processor)
->ISO150AU(Digital Isolator)->HIP2100(MOS-FET driver)->two FDD5612(N-Channel MOS-FET)

Channel is independent from FN1245.

I think FDD5612s are working in classD.

I just found this thread in Chinese forum.
http://www.erji.net/read.php?tid=823...toread=&page=1
According to this thread 2SJ554 and 2SK2955 are used in AT-HA2002 not DHA3000.

 

[Ferbose]

Quote:

Originally Posted by gajira I can't find 2SJ554 and 2SK2955 in my DHA3000. The composition of DHA3000 is AK4112BVF(DAI receiver)->SM5849BF(Digital Filter)->FN1245(PWM processor)-> ISO150AU(Digital Isolator)->two FDD5612(N-Channel MOS-FET) Channel is independent from FN1245. I think FDD5612s are working in classD.

I don't know if this should be considered as 1-bit PWM D/A conversion followed by class D amplification, or true digital amplification.
I am inclined to say this is true digital amplification, but I can be wrong.

 

[Sleestack]

Quote:

Originally Posted by Ferbose What ultimately drives the speaker is electrical current. The challenge is how you generate that electrical current from a digitized music signal. If one day we have ideal switches that can switch quickly, handle large currents and generate near-zero distortion, there is no need for analog amplification in digital audio.

Can I ask again, how is the TACT gear not true digital amplification? I'm pretty sure it is, as it does not use analog amplification. While it contains a DAC, the DAC never does any digital to analog conversion. It is in fact, a fully digital implementation of a PCM to PWM conversion, with high current output. Maybe I'm confused, here, but several people have seemed to offer input indicating that true digital amps aren't availble yet but haven't really indicated why the TACT BOZ amps are not true digital amps.

 

[kartik]

Quote:

Originally Posted by JaZZ Here's a link to an older thread. Audio-Technica's AT-DHA3000 is the only digital headphone amp I know of. .

Not a Class D amp. It is an amp with a DAC. The amplification is still analogue.

 

[kartik]

Quote:

Originally Posted by mjg Ahh I see... The only device I've seen like that is the sharp digital amp that a member brought to a meet one time. Nevermind on that... here is a link to something: http://www.hometheaterhifi.com/volum...mp-1-2002.html

would that happen to be my amp? The main advantage the sharp amp has is the matching SACD player. The signal is digital from the disc to the speaker output.

 

[mjg]

Quote:

Originally Posted by kartik would that happen to be my amp? The main advantage the sharp amp has is the matching SACD player. The signal is digital from the disc to the speaker output.

ahh yea, one of the last grado meets, that's what i was remembering.

It was the first time I've even heard of one of those.. Still have it??

 

[Sleestack]

Quote:

Originally Posted by kartik would that happen to be my amp? The main advantage the sharp amp has is the matching SACD player. The signal is digital from the disc to the speaker output.

That thing is cool. Never heard of it, but I would love to hear one. Interestingly, the writer notes that it operates at a master clock speed 4 times faster than DSD. The newer TACT BOZ amps run at a master clock speed of 35 X greater than DSD. Talk about fast moving technology. In any case, I'm a convert to digital amps and will never go back to anything else in my main systems.

 

[Ferbose]

Quote:

Originally Posted by Sleestack Can I ask again, how is the TACT gear not true digital amplification? I'm pretty sure it is, as it does not use analog amplification. While it contains a DAC, the DAC never does any digital to analog conversion. It is in fact, a fully digital implementation of a PCM to PWM conversion, with high current output. Maybe I'm confused, here, but several people have seemed to offer input indicating that true digital amps aren't availble yet but haven't really indicated why the TACT BOZ amps are not true digital amps.

If that question was directed toward me, I never said TACT is not digital amp.
In fact, I knew it is truly digital and heard one myself 4 years ago.

 

[kartik]

Quote:

Originally Posted by mjg ahh yea, one of the last grado meets, that's what i was remembering. It was the first time I've even heard of one of those.. Still have it??

Still do. Going strong, even with my increasing use of vinyl and the death of SACD.

 

[kartik]

Quote:

Originally Posted by Sleestack That thing is cool. Never heard of it, but I would love to hear one. Interestingly, the writer notes that it operates at a master clock speed 4 times faster than DSD. The newer TACT BOZ amps run at a master clock speed of 35 X greater than DSD. Talk about fast moving technology. In any case, I'm a convert to digital amps and will never go back to anything else in my main systems.

Another headfier, theaudiohobby, has the newer and more expensive Sharp DX-SX300 which samples at 11.2Mhz (1-bit word) to match the DSD player. Now that is an amp. (retails on http://www.audiocubes2.com/category/...Amplifier.html for a ridiculous 5 digit sum (not yen)).

 

[Sleestack]

Quote:

Originally Posted by kartik Another headfier, theaudiohobby, has the newer and more expensive Sharp DX-SX300 which samples at 11.2Mhz (1-bit word) to match the DSD player. Now that is an amp. (retails on http://www.audiocubes2.com/category/...Amplifier.html for a ridiculous 5 digit sum (not yen)).

The price on that is actually quite reasonablegiven its uniwue capabilities. If there was a way to couple their DSD capabilities with TACT's room correction, crossover, etc. capabilities, you would have a perfect amp. Although you can do it with the TCS, the RCS doesn't accept DSD for now.

Do you know why the Sharp goes from 150W to 200W at 8ohms and 4 ohms, respectively? The Dynamic range is also only 105dB, which seems low for a digital amp. Otherwise, I'm very interested... would make for a great SACD rig.