Digital Amps? Marketing Hype?

Call me old school, but the very notion of a digital amp does not make sense to me. Is it just marketing hype or what? As I understand it, the signal fed to the amplifier is analog (even if the source is digital, it must still be converted to analog). What would a 'digital' amp do? Amplify the signal in discrete increments?

And what about the so called 'digital speakers'? That notion seems to stretch credibility even further! (cones powered by step motors?) Your thoughts on these issues...
Well, if you do a little research, you will find that most digital amps are, in fact, class D switching amps and they work fairly well for analog audio. In fact, I find the Bel Canto eVo amps quite excellent regardless of their technology. There are also exceptions, like the TacT and the Spectron, which will accept a digitial signal directly. So, it's not just marketing hype.

As for digital speakers, again, you have to define what you mean. At the moment, I know of NO digital speakers on the market. What I do see are two things which you might be thinking of. 1)Speakers that will accept a digital input like the Meridian DSP series have in-built digital eq/crossover and amps and they are quite good, in general. 2)The so-called 'digital ready' speakers which are marketing hype.

What stimulated your annoyance?
The other side of this is a form of hype in the so called "digital ready" products. pure marketing hype.
supposedly these products are either powerful enough or 'good enough' for digital front ends. Ha hah ha...
There is digital hype, and there is analog hype, and it seems to me that I hear a lot more of the latter. Each technology has a few real advantages, and thousands of myths.

My work involves servo-controlled gimbals of a missile guidance system, and let me tell you that the digital amplifiers in the latest system run circles around the old analog amplifiers. So far my audio amplifiers are analog. One of the advantages of digital technology is circuit simplicity and low cost, but, because it's new, manufacturers have not passed the low cost benefit on to the consumer. Not yet.
My basic electronics are rusty, but as i recall amplifiers were classed by the amount on time they conducted during a single cycle of the input waveform (a sinusoid for simplicity's sake). The term digital implies discrete states,on/off, in this case the output device (tube/transistor). It may only be semantics we are arguing, but if so, then only class A amps can be truly be called analog since all other classes are on/off for portions of the cycle. In this sense, they are digital; however, by convention, they have never been described as 'digital'.
It seemed to me to describe an amplifier as digital was to suggest a completely new design that did not encompass the class designations as generally accepted.
So you are right Kr4, I do need to do some research; however, it seems to me that class D amps are not digital but rather 'described' as such. I am not familiar with the digital ammps you mentioned, but it seems they behave as DAC's. That is, they pesent to the speaker load a signal which approximates an analog signal. It is the physical limitations of the drivers (load) which actaully produce an analog signal. Your thoughts?
Use your own ears but I was ready to lay down some long green on an Ayre V5x amplifier until I heard the Spectron Musician II digital amp.

I have been through more amplifiers than I care to count in the last 10 years. Did I say twenty-eight! I have had Spectral, VTL, VAC using 300B's, MacIntosh, Sonic Frontiers, Audio Research, Graaf, Crown, single-ended 2A3's, Pass, Edge, Polyfusion, Ayre V3, ... you get the idea.

The Spectron just flat-out floored me. I have Maggie 3.6R's that demand current. This amp cuts muster. All who have been over to the house have been mightily impressed by what they hear. The amp is able to belt out 650 wpc with 40 amps peak current and the Maggies just cruise. What the Spectron does that no other digital amp has done, so far, is provide a feedback loop from the speaker. The amp takes the speaker cable out of the equation so the signal that arrives at the speaker is the same that left the amp. They accomplish this by using sense cables. The designer was an engineer in the defense industry and one of the original founders of Infinity, the famous speaker company.

With his design I hear so much deeper into the soundstage with imaging that is rock steady. I don't hear solid state or tube sound. I hear music. Dynamics are broad and transients are crisp but not biting. Bass is full and fast. No edge, no glare, no hype.

As far as cost, yeah, it should be coming down. When Bel Canto can charge nearly $3000 for their digital amp using a module that costs on the order of pocket change, that is just taking advantage of their position being one of the first to market.

I use a Sony SCD-1 SACD player with Richard Kern modifications feeding either a Reference Line passive attenuator or an over-achieving tube preamp, the Eastern Electric MiniMax. Interconnects are the Harmonic Technology Pro-Silway II's. I sold my Harmonic Technology speaker cables because the sense cables sounded so much better.
I agree with jwmazur. My speakers are way hard to drive. (DQ-10's modified for biamping).
In fact, I bought 2 PS Audio HCA-2's since I've had problems in the past trying to get life out of the bass.
I found that 1 drove them beautifully and now have the other for sale.
Jlamb, you might want to check out the Tact web site for some interesting clarification.
"So you are right Kr4, I do need to do some research;"

Yes. There's a lot of info out there. Try the Tact and Tripath websites for a start.

"however, it seems to me that class D amps are not digital but rather 'described' as such."

Depends on your definitions. I tend to agree with you but I am not bothered by this minor shading of word use.

"I am not familiar with the digital ammps you mentioned, but it seems they behave as DAC's."

Some do.

"That is, they pesent to the speaker load a signal which approximates an analog signal. It is the physical limitations of the drivers (load) which actaully produce
an analog signal. Your thoughts?"

All have a reconstruction/HF filter at their outputs, so that they output a smoothed analog signal. Relying on the speaker/crossover to do this would be an uncertain application.

I have been running a Bel Canto EVO for about a year now
and couldent imagine being with out it. I cannot find a
weakness with it. No hype just stellar performance.
I think for the price its a "steal"... I have also heard many good things about the Spectron... In fact the Spectron may be a better bang for the buck buy?.. But like i said i couldent imagine being without the Bel Canto. I havent heard much about the Tact.

Here are some direct links to the Bel Canto EVO white
paper and the Spectron amp details. These should answer
most of your questions.. I dont think someone could go
wrong with either one of these..

I am interested in digital amps also. However, checking the forum archives, i found that some of the 'uncompromising' supporters of digital amps (BC evo and Spectron) replaced (some are selling them right now) their amps for the tube amps...?

I think its only fair that we "drop some names" here?

Mine isnt fot sale and the only tube amps i will be
buying in the next couple years are tube guitar amp heads
and believe me they are not doing "exactly" what i
want... I would prefer a much "stronger", "faster"
response than im getting. But its the best we have now.
We are getting close to a better solution.

I think you can find that ANY widely selling audio device will be strongly represented on the used market pretty quickly. It is not a reflection on quality but on the nature of audiophiles.
Kr4, I agree... Its inevitable.

I do like to see people put disclaimers in their posts though. It just makes more ethical sense to me when someone is talking favorably about a piece of gear and they have it up for sale.
Thanks for the links Voodoochile! The Spectron site in particular has a good desription of the basic theory underlying their design. In short, the input signal is converted to the digital domain, then amplified; hence the moniker digital amplifier. Both digital and analog input signals are converted to PWM (Pulse Width Modulation) format and then modulate a carrier. The resulting signal is then amplified to output levels, and filtered to remove the carrier. Note that the output signal is in fact a square wave.
There are of course merits to this design because class D amplifiers are efficiency champs. Die hard 'analog' audiophiles may have issues with so much DSP (Digital Siganl Processing), however DSP chips have advanced strides in the last few decades. Indeed, audiophiles routinely talk about 'analog' sounding CD players which actually benefit from advanced DAC and DSP chips. Personally, I love my 'analog' sounding CD player and would love to hear these new digital amps. It would be interesting to hear from anyone who has compared the sound of the analog vs digital inputs on the Spectron.
Jlamb- FYI- the digital input on the Spectron amp isn't avaialble yet. Should be soon.

Performance using the balanced analog input is outstanding.
Right now, digital guitar "modeling" amps are all the rage. Even That old tube stalwart Fender has a line of these digital amps. The idea is to process analog sound through chips so that you can get a "model" of any type of sound you want. Thus, you can set your amp to "60s British Blues," or "Surf," or "Metal," and there's countless combinations. I have used these amps at jam sessions, and they are impressive, but I'll stick to my 40 watt Marshall, thank you.

ANYWAY, it got me to thinking. Will we see digital modeling amps for audiophiles? In other words, say you want that classic 70s Marantz 9 sound? There's no reason to think that manufacturers won't be able to do create a digital product that can "model" the sound of any amp you want. Cary, Conrad Johnson, Rogue, VTL--all of these have some sort of sound signature (that is electronically measured). What's stopping companies from digitally capturing these sounds? The technology exists right now; it just needs to be applied to the consumer market.

How do we feel about this? Me, it's kinda scary in that this just another example of digitizing experience. Let's face it: We're living in a digital age.
Crazy4blues...Carver already did that without the benefit of digital processing. He designed a solid state amp that was made to sound like a tube amp. He said he could tweek his amp up to match anything on the market. Reports that I read at the time said that he was quite successful.

Your welcome... I think the big advantage for the
"digital" amps utilizing DSP's is shorter signal
path. If you get a chance have a listen to The Bel
Canto EVO's and the Spectron. Im guessing either way
you wont be dissapointed.


My SS practice amp has digital modeling... I dont know
anybody who uses any of that stuff.. as you know most
of it is worthless.. Its like the Hall or jazz club
effect on a pre-pro. Anyone who knows any better cant
stand to listen to it.

What i was talking about is the actual amplifier portion of the head. Not the effects.. Im using 120w Blue Voodoo heads now.. And i used to use Marshalls 50 and 100 heads and i really wish they all were a little faster/punchier with more attack. I would be very intrested to try out a "Digital" not SS guitar head. Maybe based on Tri-path? I dont know.. but i would the first in line to try it out?

Eldartford: I'm not talking about ss amps that are supposed to sound "like" tube amps. Rather, I'm talking about *one* digital amp that can, at the flip of a switch, sound like *many* different kinds of amps. You want that sharp Krell sound? No problem. How about a 2a3 sound? Just flip the switch again. How about a tetrode push-pull kt-88 sound? Again, flip the switch.

The technology I'm talking about is the ability to digitize a sound signature and use one product to convey several different choices of sounds. I can see this as a possible direction for audiophiles.

While I don't necessarily look forward to it, I can see a day when discussion lists on this forum will concern themselves not with this or that tube, or this or that cable; rather, guys will be asking about the latest "cyroed el-84 preamp to 300B SET power amp" PATCH, which will be downlodable via usb and put into your amp. Boom, you have a different sound. See what I mean?

If I were smart enough, I would try to produce this type of product.