Wow! I didn't expect this: I think I'm done w/ analog amps (receiver or separates) (1 Viewer)

[BruceD]

Danny,

You missed my point. Even though all those mainstream receivers take in a digital signal, they first run it through the receiver's DAC (PCM) or DSP->DAC (5.1), converting it to an analog signal before presenting it to the internal digital amps (except Panny, Kenwood, and HK). Then the additional A/D/A cycle is applied. That's what I'm talking about.

TACT is the only amp product I know of (using TI chips) that also takes a direct digital signal (PCM) without an additional A/D/A cycle.

I was mistaken about HK, as the D2audio chips they use also accept direct digital input without the additional A/D/A cycle.

I'm sure many more will follow the direct digital approach as time goes by. I think many manufacturers took the fast to market route for their first designs by simply retrofitting digital amps into existing analog designs without a complete rework, i.e. simply replacing analog amps with digital amps.

 

[FeisalK]

Bruce, sorry it was rather hard for me to believe that engineers would not strive to retain signals in the digital domain once it was there, soooo I had to do some further reading/digging.

On the Tripath website (in datasheets), there's this digital controller TCD6000 (this is a PDF file)


so I think whomever is using this Tripath controller can directly amplify the digital signal without that extra D/A conversion stage in the receiver

 

[Steve_AS]

Then again, a lot of folks on those forums take dubious premises like 'burn in' of amps rather *too* seriously, and well-known factors such as expectation bias rather not seriously enough, so caveat lector.

 

[BruceD]

FeisalK,

The Teac amp is a good example of a Tripath implementation that doesn't use a digital input. I think BelCanto and others using Tripath also use analog inputs.

PS Audio is another example of a digital amp that only acceptes analog inputs.

Flying Mole is another example of a digital amp that only acceptes analog inputs (Balanced XLR or Unbalanced RCA).

Just because a digital amp chip has a digital input option, it doesn't mean it gets implemented that way. I don't have confirmation yet that HK uses the digital input functionality.

 

[FeisalK]

Steve,



true, true

 

[FeisalK]

Bruce,

oh I agree - but the amps you mentioned are all power amps, not receivers/integrateds. Obviously since these do not have a digital input, they would have to take an analog signal from a pre-amp or DAC

I guess I was thinking receivers with digital amps - those which have a digital input, and I can't see why they should do a D/A conversion before presenting the signal to the amplifier section (as you mentioned in post #81)

 

[PaulDA]

Isn't any digital amp that only takes in an analogue signal no different from any receiver that digitizes an analogue signal for manipulation via DSP? For example: I have an Integra DTR 6.4. It is a standard analogue amp receiver. On my multichannel inputs, I can (if I choose) redigitize the signal to apply bass management and speaker delay settings (though not level settings for each channel--that has to be done in my universal player). I like this feature, as it provides me with a better xover freq. for DVD-A and a better slope for SACD than is available in the player. However, it entails a layer of A/D/A from which many purists recoil. Now, some big names are being bandied about, and they seem to be doing the same thing as my receiver, an A/D/A conversion, with the exception that the last conversion happens after amplification rather than before, as in my receiver. Is it the contention that an A/D/A where the final conversion is after the amp stage is so much better that it trumps a single D/A conversion in a player, which then stays analogue all the way to the speaker? I'm really trying to understand, not trying to dis or dismiss anyone.

 

[FeisalK]

Paul,



it's not the fact that the D/A after the amp stage in a digital amp is better than the D/A before the analog amp.

think of the current that drives the speakers - there's no way of escaping that its a current; in an analog amp, the current is controlled by an analog signal; in a digital amp, that same current is controlled digitally. there's no real D/A conversion (as we usually mean it) at the output stage of a digital amp

take this back along the path, where you get a digital source (PCM, DD, DTS) that is input directly to the receiver. the digital signal is decoded if necessary (DD/DTS) and bass managed, but these same digital signals is used to control the output of the digital amp. zero conversion.

Assuming that any form of D/A A/D conversion involves sampling and all sampling is inherently flawed (in practical terms this is probably undetectable) wouldn't a receiver/amp with zero conversion theoretically be better than one with? (all other things being equal of course)

this is probably why the CD/DVD -> XR45 digital connection gets rave reviews, though it doesnt do too shabbily on the analog inputs either

 

[PaulDA]

I agree entirely with this statement. My question was about the benefit of having digital amps that have only analogue inputs (I believe Bel Canto was referenced above as such an amp). In that context, I don't see the sonic advantage, given the high quality DACs out there in standard equipment. I can imagine space efficiencies, heat efficiencies and reduced electrical consumption--all of which are desireable. Nonetheless, I can't concede a better sound, a priori.

However, in the case you describe, I can see the potential advantage, as the signal remains, essentially, unconverted.

 

[FeisalK]

That you can only decide by listening

Space, heat and power supply efficiencies could also mean directing cost to better components which would improve sound, or a cheaper digital amp that sounds as good as a more expensive analog.

Though that doesn't explain the the abovementioned Teac, at $99, or especially the little Sonic Impact T-Amp, at ~$30 having almost no other components than just a board and volume control in a plastic case. That 6moons and other reviews of the T-Amp is making me think that digital amplification is simply better (and efficiency may be a contributor or a fringe benefit).

 

[Kevin Alexander]

So are there any new owners of the Panny yet? I'm curious to hear your reviews.

 

[Nigel Hooper]

I picked up another 50 to compare to the 1014TX. Bearing in mind that the 50 has only been burning in for 72 hours at this point there's no comparison. The 1014 soundstages much better, is more authoritative and controlled in the bass, allows just as much detail through but is more natural in the highs and has a much more palpable midrange. I would say the Panny would be a good upgrade for a person with a Kenwood or an older Yamaha but at this point in my opinion it's not close to a better analogue unit.

 

[Kevin Alexander]

Nigel, you must have just sprung for a brand spanking new Pioneer VSX-1014 w/ no return privileges or a stiff restocking fee.

 

[Nigel Hooper]

No not at all and a matter of fact it was the second 50 I owned. I also had a XR10 and a XR45. Sometimes the excitement of a new purchase colors our perceptions. I will be returning the 50 and the 1014TX but there was NO contest between the two whatsoever.

 

[Chu Gai]

I think the H/K's use the TriPath chip Kevin but I'd guess there won't necessarily be any brand loyalty as this market continues to unfold. There 'might' be something to Nigel's comments if the Panasonic has a rising impedance at the upper frequency extremes in which case, depending upon the speaker's impedance curve, could have an effect on the practical frequency response. With the digital receivers, this isn't all that unusual since the rising impedance is a consequence of applying the necessary filtering for the units to meet FCC specs for RFI.

As far as that Panasonic mod on audiogon, all I can say is someone got taken with those Bybee mods when they simply could've gone to Radio Shack and added some resistors to their speaker wires :frowning:

Feisal: (Quote: "When brand new, the Panny was very bright/too bright. That has improved considerably after 4 months")
Sounds like what people say about their marriages

 

[FeisalK]

Chu, LOL.. the noise floor usually escalates after some time, except that people tend to either get used to it, or learn to tune it out (failing which, an upgrade is in order despite the fact that all equipment tend to behave this way)

p.s. H/K uses D2Audio in the DPRx005 series, although what D2Audio has inside their little black boxes...

 

[Gil D]

Nigel,

What are you returning the XR50 and Pioneer 1014 in favor of and what speakers did you use in the comparison?

BTW Does the 1014TX use digital amps (TI Equibit?) - I really don't know much about this receiver and what the buzz is all about it.

 

[Dave_vega]

got my xr50 tonight..have only had about an hour of testing on it so far, but so far all I can say is wow..what a difference from an analogue amp..hissing gone..clarity of this little guy is unreal..I don't find it bright whatsoever..I guess my speakers are a good match for it..played pearl harbour DTS track through my htpc and the difference over my jvc rx8010 receiver was quite apparent..I loved the JVC's sound though as it was very full, but the panny is also full but with a clarity the JVC lacked..mids and lows are extremely detailed where on the JVC they tended to be quite muddy..also played a few songs through DD from my satellite receiver..for some reason my JVC left out the sub channel on the satellite DD signals..I was glad to see the panny played the sub in full force..can't wait until I can get a chance to really play with it this weekend

this receiver is highly recommended from me..

 

[NickSo]

Dave: Hehe, i just picked up the XR25 tonight!!! $199.99 london drugs... last one they had in stock at the store.

I had finally convinced my dad to check it out after showing him the thread at Audiocircle where the guy said it was just as good as his tube amp... He's the old fashioned analog guy, so its quite a feat getting him to try it out.

Compared to the Yamaha RX-V450 we just bought two weeks ago, it has much better clarity in the highs... in The Eagles: HFO, you can actually hear the fingers pluck the string (like it rubbing on the string just before release). My dad notices the clarity as well from CDs.

Had it installed for about 45 mins or so, more impressions to come.

 

[Dave_vega]

awesome Nick..I would have checked out the XR25, but it did not have enough inputs for me..I maxed out the XR50 (4 inputs) , so that was a big issue for me..great price on it though..