Digital Amplifier

[tapeshc]

Hi,

You must be wondering when every one here is switching from SS to tubes, why am talking about digital amps. :)

I had been reading about these digital amps for some time and came across Panasonic SA-XR55. I did read very good things about this and other Panasonic receiver. What I liked about this is that in stereo mode it uses other channel amps for two channel. You can Bi-Amp or BiWire. All this for $229.99 at amazon.com. This is all mentioned in the manual.

Rotel just came out with RMB-1077(7 Channel Digital Amp) and Nuforce, Bel Canto are already established in this technology.

Best thing I heard about these amps is that they don’t loose steam on heavy or difficult loads and bottom end is very well defined and full.

I am thinking of trying this Panasonic offering as it wont set me back by big $s, what do you think it is a good idea ? I don’t know how close it will get me to Nuforce or Rotel. :)

Any one here has any opinion or feedback on these digital amps ?

[bknauss]

Be careful with the term "digital amps"... a lot of amps are simply switching amps (Class D, stuff like that) with no digital aspect in the amp. There definitely are some amps with digital circuitry in it (the amps used in the Polk IP speakers, Class T), but there's been a big misconception that anything very efficient is a true digital amp.
End of anal engineer.

The thing to worry about with switching/digital amps is the roll off on the high end. Without going into technical detail, its a problem that's inherint with the technology of Class D and all of its flavors and must have a good design to get around the problem.

But, as always, listen for yourself and make your own opinions. If you want opinions on a true digital amp, ask anyone who came to Polkfest. Everyone seems pretty darned impressed with the sound of the IP speakers.

[HBombToo]

When all this buzzing started a while back I had to get my research on. I found the chip sets that go into these types of products to gain a clear understanding of what is actually going on from a design perspective. I hope the following attachment takes you to an 80 Watt chip set.

http://www.apogeeddx.com/DDXi-2051.pdf

Have fun and this is a great start of a cool topic. IP audio is the way of the future IMHO!

HBomb

[Zero]

Tapesch,

Mentioning chip amplifiers can be a big no-no roun’ these parts, chose yer words wisely!

BKNauss tackled one misconception, which is one less thing I will have to cover – thanks bud! Something many do not realize is that chip amplification is nothing new to the world of electronics. Yep, old technology (20 years or so) that has seen most use in the professional field. Chip amplification is only new to home audio, and most recently, exotica.

Let us turn back the clock to six years past and for kicks, lets add a hypothetical situation. You own some fairly inefficient speakers that are spec’d out at 86db. If that’s not bad enough, they present a constant 4 ohm load and require a robust amplifier to really control their drivers. You don’t have much cash to spend and although you would like to go the separate proc/amp route, that is just not in the cards as you only have 1 large to press over the counter. Well, this doesn’t leave you with very many choices – your best bets residing in finding a used former flagship receiver from companies like Pioneer Elite, Marantz, Denon, or stepping into an entry level used NAD or Rotel receiver, and this is if fortune is smiling upon you.

Fast forward back to this point in time – the introduction of the cost effective chip amplifier has allowed manufacturers to offer up insidiously low-priced receivers that could ale your hurts. Even for as low as $300, you can take home a product that’s;

Around 80% Power efficient
Stable at a 4 ohm load – even handling 1 ohm load dips
6 discreet transistors
Offers all the theater formats you could hope for
*Some* even offer multi channel inputs for high-definition formats, ala, SACD/DVD-A

That is exciting! So by now your thinking this may be the holy Mecca of affordable multi-channel listening, and I may be inclined to agree. Like with all things however, there are trade-offs to these mouth watering enticements.

The first downer is that they are, well, cheap… No big exotica hi-fi name machined into a big solid piece of gear on your custom hi-fi rack for friends and audiofools to gawk at. There is nothing cool about a piece of equipment that is so easily accessible that even granny could pick one up at the local Sam’s Club.

The second downer is that they are, well, very cheap. Nope, no giant heat sinks, no hefty WBT posts or RCA’s, solid bezels, Auricaps, Silver wiring or dual heavy duty torroidal transformers with detachable power-cords. You are getting bottom of the barrel parts straight outta’ the factories from China.

So why on earth would any company use a chip amplifier only to massacre it with cheap parts? Well, that’s because these transistors are insanely cheap when purchased in bulk. We are talking about maybe a buck or two folks.

By now, you may be asking yourself why this yokel keeps rambling and just what hands-on experience he has ascertained. It is best to warn you that if you haven’t asked that and if you do not care, just skip this part and scroll down to the last paragraph.

I began tinkering with various chip amplifier products a good year and a half ago when hype began to really surface in the audio communities. It is really easy to get caught up in the thought of paying nothing and getting everything – and to this day that is still fiction. If there is any useful piece of advice I could offer you through my experiences, it is to keep your expectations realistic. The next piece of advice I have to offer is that most of these products sound different, some being even completely opposite. Let me give you an example;

I owned the infamous JVC RX-10, this inexpensive 6.1 receiver that many claimed to rival their exotic tube based equipment. Let me tell you, nothing will trigger an audiophile quicker than a claim that some $300 unit even has the capacity to sound like tube. Ignorance is bliss, sometimes. This particular unit had that ‘whole’ flavor. You had the rolled off top end, mid-bass ‘blossom’, with extra kick in the bass region. I compared it directly to an entry level Jolida in the same price-range and yep, she did that tube-thingy, even better than the Jolida. The problem is; What I just described is NOT what tubes should sound like. It is very easy to make a tube product, thusly, there are a lot of real crappy tube equipment out there.

Now, we had the Sony 50ES (damn, forgot the model number). This unit even had a built in dvd / sacd player. Now my parents have seen and consequently heard many of the products that have come and gone through my home throughout the years. To this day, this unit is the only electronics piece that ever captured their interest. Why? Because they heard details they’ve never heard before! This is a pretty big deal, and while I can’t afford to bring home ‘big game’ – I’ve had great stuff in here before. Just the same, this product was the opposite of that JVC. The highs were extended beyond belief, incredible control over the drivers with very tight bass (reminded me much of Krell). Insane dynamics and great resolution / detail. Sounds perfect eh? It might have been, but it just didn’t have that cream filling.

This response has taken an entirety of its own so before I have to submit this piece to an audio mag in crossing my fingers for a job – I will cut this short.

Bottom of the line is that you will read many claiming that product X is the best thing since girls gone wild. I have experienced that tube-like sound so many refer to from their inexpensive boxes. I have heard these affordable products trounce the daylights out of gear I dare not mention here or anywhere else… and I have also heard the sterile, hollow sound many report. I have also heard these affordable products get put right in their place by a competently designed, albeit more expensive system.

As the old adage goes; “You get whatchu pay for”. Fortunately in this circumstance, that’s not a lot. Go out and give these units a whirl. Remember to allow between 200-300 hours of break-in and determine if these units appeal to you!

[cfrizz]

Zero, I understand that the recievers are not all that they are pumped up to be, however, what about the Rotel that is making strictly amplifiers? What is the difference in technology there & does it measure up to standard amp technology?

[HBombToo]

Great outline and detail Zero.

I'll just add that there is a cool factor to this IMO and really enjoy watching new product development.

HBomb

[Zero]

Cfrizz,

The problem is that a select vocal few have proclaimed these cheap receivers to de-thrown not just very well respected multi thousand dollar receivers but also stereo separates in the same price-range. In audio, you just “don’t go there”. I will not insult your intelligence by expanding on that topic as you know what high expectations through hyped claims can do…

I am honestly not up-to-date with what Rotel is doing with chip transistors, as far as I knew Rotel bulked up on stock like all the other manufacturers of the sort.

As an aside, most of the esoteric brands that use this approach take these chip transistors and supply them with adequate, if not over-built power supplies. What you pay for are top shelf components (capacitors, attenuator, RCA’s, Binding posts) along with what is usually a much better design sporting a solid chassis with a touch of tuning and attention to other fine details.

The grape vine has it that Rotel’s new amplifiers are beasts. I hope to give them a spin one day.

[cfrizz]

Understood! I will wait until the people I trust on this board have a chance to check them out & weigh in with their opinions!

Thanks,
Cathy

[tapeshc]

Zero,

Thanks for your indepth analysis.

Here is the Link that got me started on this search.

Also what I have heard about Nuforce is all good or amazing I would say. May not be tube like but one of the best.

Jeff Rowland's latest offerings are also using this new technology, ofcourse with their added research.

Panasonic ? Yes you are right, you get what you pay. Its cheap construction wise, but sound seems to be good (heard so). Again its all hear-say, so needed some kind of approval from my good old friends here :)

[Zero]

CFrizz,

I would imagine that in the following six months, reports on these new amplifiers will trickle into this forum. Rotel has a loyal following over in this neck of the cyber woods.

Tapeshc,

I too have followed Nu Force for the past few months. This is yet another situation to where I wish I had free cash to bleed out on these cool new toys!

Chip transistors are here to stay. I would give it roughly 6-7 years until traditional solid state amplifiers will retreat to the esoteric side of this hobby. It will be interesting to see where the future goes...!

[AsSiMiLaTeD]

Whatever happened to that little Teac amp I was hearing so much about? I can't hardly find any information on it online. Sean, you still liking yours? Know where I can find a few pics and maybe a manual. I'm thinking of hooking one up in the bedroom, am wondering if I'll need a preamp...

[Danny Tse]

Here's one of the discussions of the TEAC power amp at audiocircle.com. You can do a search at the "Multichannel Audio and the Digital Domain" section of that site for discussions on other such amps/receivers. The consensus is that the TEAC functions much better with a pre-amp (even though each channel offers its own volume control).

There's now buzz generated on the 'net about Onkyo's TX-LR552 digital receiver. It's been out for a while but has been overshadowed by the Panasonic and JVC offerings. You can pick up one of these for about $150.00 brand new.

[AsSiMiLaTeD]

wish I could find a picture of the back...

[hoosier21]

here is a link to the rear of a modified Teac, it has a few things removed but you get the idea.

http://www.boldercables.com/Merchant.../1168/teac.JPG

I have three of these amps

[Danny Tse]

here is a link to the rear of a modified Teac, it has a few things removed but you get the idea.

http://www.boldercables.com/Merchant.../1168/teac.JPG

I have three of these amps

Looks like it's been modded for 2 channel operation, which was my original intention as well.

[Zero]

Hoosier,

If you dont mind taking the time - I would love to hear your thoughts on the modified amps. Feel free to PM if you want to keep it private.


Polkmaniac,

As tough as this may be to digest - the Teac is still in my home and still see's nearly daily use on the PC rig. I have her driving a pair of LSi-7's at the moment.

I tell you, that little Teac is my diamond in the rough.

I believe www.needledoctor.com had these available, although I am not sure if they still are or not. Amazon.com will occasionally have a few pop up as well.

[AsSiMiLaTeD]

so it looks like with the volume controls on the back that I wouldn't need a preamp to work with the Teac...

[hoosier21]

so it looks like with the volume controls on the back that I wouldn't need a preamp to work with the Teac...

Each channel has a vol control.

ZERO
Sorry for the misleading post, I could only find a picture of the rear of the amp on the net, and it is a modded version. Mine are not modded. I have not really even played with any of the amps I got, sitting pretty in the box they were shipped in. I will use one with the R15 I got from Madmax here at work.

[AsSiMiLaTeD]

Each channel has a vol control.

ZERO
Sorry for the misleading post, I could only find a picture of the rear of the amp on the net, and it is a modded version. Mine are not modded. I have not really even played with any of the amps I got, sitting pretty in the box they were shipped in. I will use one with the R15 I got from Madmax here at work.

wanna sell me one :D ?

[madmax]

I'm using one of the Teacs currently with my B&W DM4's. I've played with the Teac and the Sonic impact. Both have the same distinguishable sound. It is almost like listening to an electrostatic speaker. Actually, I noticed the same characteristic when we listened to the powered speakers at polk. I don't mind this characteristic but it is there. Can you still order the Teac? I bought two at the time because I thought they were becoming scarce. Cool little amp!
madmax

[AsSiMiLaTeD]

Hell no you can't buy them...I'm looking online and can't find one anywhere right now...

[Danny Tse]

TEAC A-L700P power amp.....$97.00

http://dakmart.com/website/ItemDetai...=42161&cID=110

[hoosier21]

Hell no you can't buy them...I'm looking online and can't find one anywhere right now...

Collector's item, rare item.... hmm pricing just went up. :D

[AsSiMiLaTeD]

TEAC A-L700P power amp.....$97.00

http://dakmart.com/website/ItemDetai...=42161&cID=110

Sweet!

[madmax]

In my opinion the sound quality is worth much more than the asking price.
madmax

[AsSiMiLaTeD]

So those of you using these, are you using these with or without a preamp? This would be nice for a bedroom system because I can hide it from view if I can use it without a preamp. I've already got a Denon DVD player in there that does a good job as a CD player...just need some speakers...

[AsSiMiLaTeD]

I know this is subjective and really doesn't matter because I'm going to buy one regardless...but...

If you had to put a price tag on this piece in terms of sound quality (compared to other amps that are out there), what range would it fall in?

[hoosier21]

If you have a Denon with variable out, I would not use a preamp. But I would not plan on using the pots on the back, they are hard to get to, they are small, and there is one for each channel, would be a pain.

[Zero]

Hoosier 21,

No problemo. I ran the R15's with the Teac a week ago and I must say, that little combo sports a fantastic value.

PolkManiac,

If you were to give this amplifier a big chassis, slap an audiophile approved name on it and retain all the electrical components and design, I could easily see this unit being considered a great value at even the $899 price-point. I've put some very expensive speakers on this amplifier, and have compared it to very well respected seperates and what can I say - - my mouth will remain closed as to how I really felt - but I am sure you can pick up my subliminal message in there.

As Hoosier states, the volume pot is per-channel. Get a pre-amp...preferably tube or passive.

[AsSiMiLaTeD]

Any preamp in the $100 range you can suggest?