I know this issue has been discussed extensively in the past, but I thought I'd solicit some new feedback -- particularly since a lot of work has been done addressing the various issues of these two processors.

So, any votes for which of these two delivers the best features and performance?

Let's see if I can remember *my* list"

1) Outlaw has BM on the analog inputs, the Rotel doesn't.

2) Both have the double bass problem on the 5.1 inputs, but if you do use the 80 Hz analog crossover on the 950, no double bass. There is a way to get around the double bass on the Rotel: buy a $249 Outlaw ICBM.

3) You must have the Rotel connected to a display (TV) to access the menus. You can use the 950's own screen for this.

4) The 1066 has 24/96 DACs. The Outlaw has 24/192's.

5) The Outlaw has a tuner, the Rotel doesn't.

6) I know that the 950 has mono rears for any of it's 7.1 modes. I have been told by users of the 1066 that it has stereo rears. But this seems suspicious in that both use the same Cirrus DSP engine. But it could be true. (An ad I saw recently said, "... the enhanced discrete stereo surround of 7.1," FWIW.)

7) You can upgrade the software on the 1066. Can't on the 950.

8) I think both of them could look better. The 950 needs to get rid of the green power button (I've alread put black electrical tape on mine ), and the rubber volume knob feels cheap. My opinion. The 1066 looks a lot better, but to me, put the volume knob on the right, and re-center everything else. To much "empty space" on the left side of the unit.

A nice looking pre/pro? The B&K Ref 50. I think the new Sunfire looks terrible, as well as the Anthem. To many buttons and graphics on the front.

9) A 5 year warranty that is transferable on the 950. I know that the 1066 warranty is not, but I don't know how long it is. (2 years?)

10) The 1066 lists for $1500 or so. The 950 is $899. My local dealer wasn't discounting the 1066 at all when I asked Sept/Oct. The lowest I've seen people pay is maybe $1250. That's still more than 1/3 the price of the 950.


Performance? I haven't seen a direct comparison between the latest (blue dot/equivalent), or even the red dot (or equivalent) version of the 950 and the 1066.

Early comments were that the Rotel was "warmer" and the 950 was "brighter". IMO, behind those words is this: if I want warmth, I'd buy tubed gear. Along with all the harmonic distortion you get too. "Bright" is generally taken to be more accurate and revealing. "Warm" is more forgiving of the source." "Bright" isn't. Me? I want accuracy, no double bass, and BM on the 5.1 analog inputs. But everyone has to decide what they each want...



[This message has been edited by Kevin C Brown (edited January 13, 2003).]

It seems possible that at least some of the perceived difference in sound might have been due to the previously elevated noise floor of the 950 or other design choices that are now altered in order to lower the noise. Is it possible they sound more similar now?

Kevin:

You're welcome to stop by any time and bask in all that Harmonic Distortion

SH- I thought y'all might say something about that... I got no problem with tubed gear being used to *create* sound. (Heck, tube guitar amps *are* the best sounding amps IMO.) But to *recreate* sound? I'll go for the emotionlessness and sterileness of solid state every time for the most accurate reproduction of a signal that already exists...

Kevin:

My My, I don't think you fully understand the myriad of issues involved in 'distortion' in vacuum tube design. It is not as simple as as it seems by a long shot, and it certainly can't be put in a convenient box lablled 'harmonic distorion'. Do you have any _direct_ experience in vacuum tube verses solid state design other than once owning a tubed guitar amp? I don't mean to be harsh about it, but you seem to be reguritating the same mis-informed opinions that are very common among people who have never actually done extended research and listening into the subject. There are good and bad examples of _every_ technology, tube or solid state, and to gloss them over by pointing a finger at one single parameter without any regard to specifics of the design in it's entireity is not good form.

[This message has been edited by soundhound (edited January 13, 2003).]

SH: When I see measurements of a component with 2 - 3% of harmonic distortion under any circumstances that was not present in the original signal, I'll pass. I recognize that some people prefer that under some conditons. Not me.


[This message has been edited by Kevin C Brown (edited January 13, 2003).]

Kevin:

And what amplifier might that be?? A guitar amp? Did you measure it yourself, at what power, what frequency? Please do not generalize about this kind of stuff, BE SPECIFIC. I get about .03% from all of my amps _measured_.

Old measurements in Audio, Stereo Review, and even current generation equipment being measured in Stereophile.

Neither of you are from Arizona are you?
Not to wonder off topic but, SH is there a good place to start with tubes that is not to expensive. Perhaps a amp or pre-amp you could recommend! I would like to add some tubes to my HT!




------------------
m-mmeyer
GO TWINS
My DVD's

I do get the difference between even ordered harmonics for tube gear being preferred over the odd-ordered harmonics for solid state for sound quality itself. But 2-3% vs say 0.06%?

Here's one I found:

Antique Sound Lab MG-SI15DT Integrated Tube Amplifier - Single Ended, Pure Class A Operation

Rated Power: 5 Watts RMS Per Channel into 8 Ohms in Triode Mode, 15 Watts RMS Per Channel in Tetrode Mode

THD: < 2.5% at 5 Watts, S/N: 78 dB, MFR: 17 Hz - 28 kHz ±1 dB at Full Output, Size: 7 3/4" H x 19" W x 18 1/4" D, Weight: 25 Pounds, MSRP: $699 USA

An admittedly "entry level" tube component, for $700...

Another, more premium one:

http://www.stereophile.com/showarchives.cgi?687:6

See Fig. 3.

Again, Kevin, what power level, what kind of tube amp - class "A", "A/B"? I mention this because tube amps have extremely different distortion behavior than solid state ones. Since the 'knee' is so broad at the level where distortion starts to increase, you can 'measure' just about any distortion you like, depending on the power level. Tube amps have comparable distortion to solid state at levels below this 'knee', which occurs near full power. Also, as you probably know, tubes have almost no distortion components beyond the 3rd harmonic, which is musically related (the octave + a 5th) In addition, and this is not well known, the phase of the distortion components is not corrupted relative to the fundamental as it is in solid state: they are in their proper in-phase condition, unlike solid state, which corrupts the phase of what distortion it produces. This is one very big reason that even comparatively small levels of distortion in solid state amps sounds objectionable. Tube amps have a far 'richer' biasing into class "A/B" than solid state, which produces less distortion at the crossover point in a push-pull amp: this must be made up for by high levels of negative feedback in a solid state amp. Tube amps use _much_ less global negative feedback than solid state, and avoids TIM (transient intermodulation distortion) entirely, unlike solid state. And finally, tube amps have power supplies which can store easily an order of magnitude more energy than solid state by virtue of the higher power supply voltages utilized relative to the filter capacitance. It would be all but impossible for a solid state amp to have enough filter capacitance to compete with a tubed amp in this respect. This means that tube amps do not modulate their power supply nearly as much as a solid state one.

And, do you REALLY think that I would use an amplifier that had as much distortion as you say in my system, which is used for critical listening to master, edit and mix music? I don't think so.

You still did not give specifics as to the actual amplifier (s), that Stereophile et.al. measured, and under what circumstances they measured them.

I really don't care if you like tube amps or not. What I object to is throwing out blanket comdemnations about something you have not actually had _direct_ experience with, having only read it in a magazine somewhere. How would you feel if I told you that a particular component _you_ have can't possibly sound good or be of any use as an _accurate_ sound reporducer, and have as my only backup something I read. I really am surprised you are willing to throw out opinions on something you obviously don't care to research, much less care about.

I've heard good things about the Van-Alstine modded Dynaco ST-70, plan to get the mod for my ST when I have time to fool with it. ST-70s are all over eBay.

http://www.avahifi.com/
http://www.netaxs.com/~vkalia/st70-rebuild3.html

But I'm far from a 'tube guy', so ask around.

SH - Any info on ST-70 mods/upgrades?

EDIT - The only gripe I have with tubes in general is the power/$$$ ratio is pretty low, but if you're using high efficiency speakers (or I guess if you have a lot of $$$) a lot of that goes away. I liked the way the ST-70 sounded back when I had it hooked up, and honestly the only things I noticed in that time were (1) it looked REALLY cool and (2) it was a bit anemic compared to my m1.5t. Nothing earth shattering there, is there?

[This message has been edited by charlie (edited January 13, 2003).]

Kevin:

Again you are taking an extreme example. I actually have a single ended class"A" triode amp that I use for my tweeters, and I get .04% distortion from it at levels below the onset of clipping. A class "A" single ended triode amp has an _exetemely_ broad 'knee' of the onset of distortion. Below that 'knee' the distortion is _much_ less. With a single ended triode amp, you could measure 20% or more distortion if you pushed it hard enough. IT DEPENDS ON WHERE YOU MEASURE THE DISTORTION!

m-mmeyer:

I'm not from Arizona, but I've been there a few times

There are quite a few manufacturers of new tubed amps now. Sonic Frontiers got their start building them, and might still make them. There are also some good ones that don't cost a lot from companies like Asusa, SoundValves (Sound Values) and others. I'm sorry I don't have a lot of names handy, but you can probably turn up some names with a web search. Of course you can pay BIG bucks for a tube amp, and I do not think that those are worth the money, but they sure have purty brushed aluminum faceplates. There are plenty of manufacturers of vacuum tubes (the tubes themselves) also, most come from Russia and other former eastern bloc countries, but they make good stuff.

tubes work if your heat pump dies. tubes...didn't he star in jurassic park??

at the show...
1.) sunfire cinema 7 signature 400wpc @ 8 ohms

2.) linn klimax 500w monoblock

3.) spectron class d musicianII 500wpc

sahweeeeeeeeeeeeeet! no toob-tester required

Charlie:

I don't think the mods are being made for the ST-70 anymore. The original circuit was pretty simple, and had some comprimises, but the basic guts like the transformers were excellent.

Yes, you are quite correct - you shouldn't buy a tube amp for 'bang for the buck"! You have to be very careful about what they are connected to. Generally, speakers that need a lot of power, and / or have complex crossover networks are not a good candidate. On the other hand, tube amps shine with horn speakers, in fact they are almost mandatory for high efficiency horns that have corssovers much below 2Khz. It's all a matter of application. The amp that drives my tweeter horns (1,200Hz and above) has only 5 watts, but with sensitivities of 106db for _one_ watt, I am asking for much less than one watt, even at ear bleed levels.

Bosso:

I only need _10_ Good watts....

Actually now, there are a lot of solid state designs that don't use much if any negative feedback, i.e., the Japanese in the early 90's using negative feedback to get great measurement numbers but poor sound. And the backlash against that.

Never condemned tubes. Just not for me. I guess here's some questions: for a 7 channel system, and wanting to play movies, multichannel audio at 75 to 85 dB with enough headroom to not get any distortion from overloading the amp, how much would that run for a tube setup? And then how often do you have to replace tubes to make sure that no sound quality degredation is occurring?

All fair questions when comparing the two.



No, of course not. You like the sound that you get. But I don't even like the idea of distortion. Kind of like being a germ-a-phobe. I had Velodyne servo subs for 4 years, and now a Vandersteen sub with FFEC (feed forward error correction) for the past 2 years, both manufacturer's use mechanisms to minimize distortion, for a reasonable cost, without going long-throw or big driver area.


All I know, is that the Rotel 1066 doesn't have a tuner, but the 950 does...

Excuse me I must have stepped onto the wrong elevator, I was looking for the 950 vs Rotel 1066. But I guess that thread went down the tube......

Kevin:

To answer your questions:

I certainly do _not_ advocate using tube amps in a home theater (or stereo) unless one is willing and able to spend the necessary money, has _compatible_ components, and willing to take the time necessary to maintain them. They are certainly not for everybody. I have a long background in electronic design, specifically dealing with sound equipment, so I have the ability to get the requsite performance from them. I have deeply modified all my tube gear - nothing is 'stock'.


The tube replacement interval is about every 5 years for power tubes (much longer in a couple of my power amps) and 10 or more years for low-level tubes. Adjusted for inflation, the tubes themselves are as cheap or cheaper than they were in the 1950s. A good 6L6 output tube can be had for $15. Having regulated power supplies for the filaments is one crucial thing that must be done to get the maximum life.

You may be adverse to distortion in your equipment, but don't make the mistake of focusing on that one parameter too much at the expense of looking at other things that can contaminate an audio signal as much, or more so! The one people seem to overlook, which is vital, is room dimentions and acoustics, for one.

Dobeman:

Yeah, it's best to put your flak jacket on when entering here, at least tonight

The Van-Alstine mod is at least still marketed, although I guess there's no way to know whether or not they're still provisioning customers. Here is the link to the mod:

http://www.avahifi.com/root/equipment/amplifier/super70i_rebuild.htm

They claim to keep the good stuff and pretty much completely redo the guts, using different tubes even. The cost is fairly reasonable and it has several good reviews.

Chalie:

Looked at the link - I guess they still are available, I just hadn't heard from them for a long time. The input tubes they are using is the usual one for a lot of ST-70 mods. It is a combination pentode/triode that is an input gain and phase splitter in one tube, as was the original. The new one is better however. I actually hoarded a load of the original 7199 tubes before they bacame impossible to get - maybe I should sell them on eBay

Interesting Reading about tube amps

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MeanGene's Home

[This message has been edited by MeanGene (edited January 14, 2003).]

Well, gots to admit I learned something new today.

Something else to look into, and maybe at least someday try to compare to what I have now... (Part of me says "dang", and part of me says "cool...")


For kicks:

http://ubb.outlawaudio.com/ubb/Forum6/HTML/000190.html


[This message has been edited by Kevin C Brown (edited January 14, 2003).]

How in the Hell did you guys get so off track here?!?

____________________________________________

we basically all know that the 1066, though a good unit for the money, costs 40% more, has no tuner, has less warranty that's backed by weaker consumer-service...through a dealer, has double bass (a bad thing) and well...isn't made by outlaws for outlaws.

a pitcher of margaritas makes an outlaw rowdy, and who can resist razzin' soundhound about his glowing closet????

SH: you need more than 10 watts, good or otherwise, to allow for transients in that monster rig of yours, and i'll guarantee you have it too! BTW, what's it gonna take to get you to listen to dvd-a/sacd??

tape--->tubes--->more tubes--->speakers
VS.
high-res digital--->digital--->class d---> speakers

heavyweight title bout coming soon...place your bets...

That was a good joust, entertaining and enlighting.

Things must have gotten a bit rowdy here last night, since my internet connection was fried today, and I just got it back. Well, as they say, if noth'in gets broke, 'ya ain't having a good party.

Bosso:

I wasn't kidding about the 10 watts! With 106db for one watt efficiency, you can see that I am just crusin' at even 100 or more db SPL. The amp (tube, of course) that runs the woofers on my main speakers can put out 60 watts, and they must reproduce only down to 60Hz. You can see that it doesn't take much power with that much efficiency. The subs are a different story though - I use all of those 1000 watts sometimes when reproducing bass down in the range of 20Hz or below. Even the subwofers are pretty efficient however as such speakers go. Each side has two 8 cubic foot enclosures and the subs are in a 3/4 space acoustically (i.e., a corner) , so there is a lot of room gain. Also, there's a great deal of mutual coupling between the two woofers on each side, and between the left side and right side of the room on deep bass. I'm probably getting a total of 12db or so more signal from room gain and mutual coupling.

I'm waiting on SACD / DVD-A until I can get a universal player that is a couple generations more along the obsolence path. I've gotta be truthful too, that I find it a bit weird the way some popular music albums are being mixed/re-mixed. I just can't get used to important instruments coming from my side or behind me - it activates my 'fight or flight' animal instincts, and distracts me from the overall message of the music. Maybe I'm just too steeped in the traditional 'performance model' of having performers in front of me. Maybe I'll get over it with time. One interesting bit of trivia - when quadraphonic (yes, I was alive then) was being introduced in the early 1970s, one of the big classical demos was Berlioz's Requiem which was originally arranged to four brass choirs in the four corners of the church. You couldn't go to a demo room without hearing it.

In the meantime, I hear a lot of surround music in my work, and mix and edit a good deal too (mostly orchestral scores).

[This message has been edited by soundhound (edited January 14, 2003).]

I guess this Outlaw stuff is catching. Could not a smiley face with a cowboy hat?

Most people will think this is Outlawish, but I use a Mesa/Boogie Stategy 400 tube amp. Yes, it was a guitar amp, and by changing some of the tubes (now at 12 6L6's), could be used for Home stereo. I think it sounds great. I have never been able to audibly hear it reach any ceiling that I could take. Maybe because I use full range speakers each with two 10" woofers a 6" midrange and the Heil Air Motion Tweeter. Then there are four of those along with two 15" subs. So you can see that in a regular size room I can't turn it up two much.

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MeanGene's Home

[This message has been edited by MeanGene (edited January 16, 2003).]

[This message has been edited by MeanGene (edited January 16, 2003).]

I think I heard an ad on the radio the other day. The Tubes are playing an exclusive show up in Marin County somewhere...

Do you think an impulse based test like an MLS system would show this, by avoiding the steady state tone as used in more conventional tests?

Charlie:

I don't think the MLS tests would necessairly be of any more use than a conventional distortion analyzer and ocilloscope (I''m assuming you are talking about electronic measurements here, not acoustic ones). If you zoom in enough at the crossover point of the wave on a solid state amp, you can sometimes see the 'glitch'. With high sensitivity speakers, it can be heard as a 'roughness' and 'courseness' to low level signals. In extreme cases, I have heard the sound actually dropping out as the wave transitioned the crossover point - it sounds a lot like a low bit rate digital recording, without dither added (sort of like telephones can sound if the sound was digitized at some point). Since on a tube amp each half of the push-pull stage is essentially operating class "A" for a significant amount of it's power range, there is no crossover notch to be generated. By the time it does cross into class "A/B", any crossover glitch is a small proportion of the total signal level. A solid state amp generally is designed to have very little overlap of the positive and negative swings of the wave. Of course a solid state amp can be constructed that has a richer biasing, even pure class "A". This is almost never done however except for very high-end (and expensive) amps due to the costs and amount of heat generated. This heat becomes even more of an issue in a multi-channel amp intended for home theater.

[This message has been edited by soundhound (edited January 20, 2003).]

Yep - I'm talking about using an MLS system to generate the 'signal' and analyze the result as captured from the amp outputs, without generating any messy sound waves.

I was actually more wondering about TIM than crossover distortion - crossover distortion is pretty easy to observe with a digital scope and some care. What do you think? I'll probably try it sooner or later - just for kicks.

EDIT - It just occurred to me that the levels of TIM (IIRC) are pretty low percentage wise, so I wonder if MLS would be sensitive enough to detect it without super expensive capture devices...

I suppose one could run multiple samples to increase the sensitivity, I think so anyway.

[This message has been edited by charlie (edited January 20, 2003).]

I've never used the MLS system to specifically look for TIM distortion, so you will be charting some interesting territory.

Yeah, I'm sure someone somewhere has done it. I've looked at tests of other (non-speaker/microphone) stuff like soundcards and amps using MLS, but I'm not sure they were specifically looking for TIM.

It seems like the 'chirp' would tend to excite a different response than a steady tone if there is a significant time factor present though.

I don't think there is any 'storage' mechanism involved in TIM, unlike a resonance in a speaker. But the test would prove this one way or another.

Actually I was referring to the 'delay' in getting the global negative feedback around to the input again. If this is a significant source of distortion it seems like an impulse test of some sort would excite it, maybe?

Yes, It would seem to catch that latency. BTW, it's that 'always lagging the signal' nature of negative feedback (even though it's extremely small) that makes me shy away from large amounts of it - or entirely

http://www.duncanamps.com/technical/microphonic.html

On Mon, 04 May 1998 09:44:57 -0800, czempel@ns.net (Chip Zempel) wrote:

>I was reading some of the amp reviews at Harmony Central, and saw several
>mentions of people having trouble with tubes that were (doing? exhibiting?
>experiencing? picking up?) microphonics. What is this? What what causes it
>and what are the symptoms? Is it fixed by replacing the tube?

Chip,

The tube is made up of a number of metal parts assembled together inside the glass envelope. If shocked mechanically, these metal parts can move, and in doing so will alter their capacitance and position such that a variation in voltage is produced.

Much the same way as a microphone. Mechanical impulses are turned into voltage. Trouble is, some tubes don't do it very much, and some do it a lot! The ones that do it a lot fit the description of "microphonic" you saw at Harmony Central. In extreme cases, you can get feedback from the amp.

If the tubes are reasonably easy to access on your amp, you could try tapping them (gently) with a pencil, and listen to them act as a microphone!

ps: not all the tubes will make the same amount of noise, a loud one may not be the most microphonic, it may just be placed where in a high gain stage where it is easier to pick up the dink-dink from the glass...

Best Regards,
Duncan

At 08:40 PM 5/5/98 +0100, Kevin wrote:
Great expanation. I just want to add a point to the original poster
since on occasion guys get freaked when any tube makes a noise when
tapped on. In some positions any tube you put in will make a noise if
you tap it. It's normal. True microphony will rear it's ugly head and
make itself known with the most obnoxious distortion you can imagine.
A smidge of microphony can (at least in the hi-fi world) add a sense of
"air". That's why some guys buy tube dampers and find it sounds better
without them. Sometimes.


http://www.stereophile.com/showarchives.cgi?351:3

Of the three pairs of 2A3s, the AVVT mesh plates were the most distinctive, visually and sonically. These big, macho tubes are considerably taller than the other 2A3s, and had by far the most dynamic presentation. It was an exciting sound, and the soundstage seemed even deeper than usual. In fact, I began to wonder if the sound of the recordings was being enhanced in some way, almost like one of those analog reverb devices used by studios before digital.
I'd heard rumors about AVVT 2A3 mesh plates being microphonic, so I did a bit of informal testing. Tapping the tube gently, or even tapping the amplifier chassis, resulted in a clear bong coming through the speakers. (The response to tapping the amplifier chassis was greater when the amplifiers were not supported by the Aurios.) With the other tubes (2A3 or 45), the same sort of tap produced hardly any sound.

Then, in an even more literal test of microphonics, I got within a few inches of the tube and sang at it, as if it were a microphone. I was going to have my wife listen to the speaker to check if my voice was being amplified, but I didn't have to: when I stopped singing, I could hear the echo of my voice coming from the speaker! The sound-pressure level produced by a person singing a few inches from the tube is undoubtedly much louder than the sound that would normally reach the tube from the system itself, but this level of microphonic response can't be good for unvarnished sonic fidelity.

I think the gist of the string here was TIM in solid state amps verses tube amps, and possibly using MLS analysis to evaluate it. That is not the same thing as micorphnonic tubes, although they can (like capacitors!) exhibit it. Bottom line, don't set your tube amp (or solid state one for that matter) on top of your speakers

Great post though!


[This message has been edited by soundhound (edited January 21, 2003).]

With the talk here about single ended triode (SET) amps, some of you may not be familiar with them. Even if you can't read schemetics, looking at the attached schematic of one channel of my SET amp, you can see the very straightforward and simple nature of the circuit compared to a typical solid state amplifier. This simplicity is one reason they sound so good. Notice that there is no global negative feedback whatsoever.