Model 200 amps until I read the several threads here about their hiss problems.

May I ask, why exactly would these amps hiss? Users here have said that their 755's, etc do not hiss, but the Model 200's will hiss on exactly the same system. Why would this happen, could anybody please speculate?

Thanks in advance...

Since I don't consider the M200's to have a hiss problem (the pair driving my Studio/60's certainly don't), I did some digging through threads to see what sorts of hiss problems have cropped up here in the M200 forum. Many of the cases I've seen have been the result of ground loops or other equipment (space heater, dimmer) on the same circuit. As to why an M200 would be affected by a ground loop that didn't affect a 755, I'm not sure.

I don't see the several threads. In the only one with the word hiss in the title, I spoke of mine having a slight hiss that was only audible if you got your ear within two inches of the tweeter. The surrounds in my setup have the same degree of noise, but they are driven by my receiver, so it ain't the M-200's.

Yes you are correct, I should have said several members and not several threads - and even then, not all the members that mentioned the hiss considered it much of a problem or design defect. Looking again, I really only see two threads that talk about this at any length:

http://ubb.outlawaudio.com/ubb/ultimatebb.php?ubb=get_topic;f=10;t=000044#000007

http://ubb.outlawaudio.com/ubb/ultimatebb.php?ubb=get_topic;f=18;t=000127#000000

The first thread listed above was the one that really got me worried. Those comments there from alzy101 actually stopped me from buying the M200's, well at least so far.

Does anybody have any idea at all why the M200's caused such a significant hiss problem in that system, whereas the 755 in the exact same system would not have any hiss issues at all? Very curious about that...

It's hard to say with the information at hand. It could be that alzy101's amps were plugged into a different circuit, or that their interconnects were routed differently than previous amps and got tangled in some power cords - hiss at a distance of 12" from the speaker isn't difficult to produce with cabling, particularly with high efficiency speakers (I've done it with my Paradigms, which are pretty middle of the road on efficiency, and fixed it with some wire management). I'm not sure what speakers alzy101 is running, but yaffstone has Klipshs, which tend to have very high efficiency ratings and are therefore easily susceptible to minor system effects. I will offer this bit of first-hand experience, though: I'm running a pair of M200's and a 750 (the 755's predecessor), and the amps produce no audible hiss even with an ear at the grille cloth.

My 2 M200 are dead quiet, no hiss at all from my PSB Image Towers, and as gonk said, even with an ear at grille cloth.

Thanks to everyone who has replied so far. Perhaps I should order a bunch of these M200s after all!

So is it true then, that alzy101's very bad experience with the M200s was unique? Has anyone else, AT ALL, had any hiss, or any other problems whatsoever, with the M200s? Or is the general concensus that these little amps are well worth it?

5 M-200's, 0 Hiss

you can get a hiss from any system depending on wiring. i would say the hisses people experienced are not due to the m200s but more of an upstream issue.

I reiterate: 5 M200s, no hiss unless you are very very close to the speaker (Dynaudio). I am very pleased with mine and would not hesitate to buy more (7.1?) Good luck.

I'm using a pair of 200s in two channel mode with an old set-up of a Sony TAE1000ES preamp powering a pair of KEF 104/2s. The only time I ever heard a hiss was in my previous home where the outlets were ungrounded. My new home has 30 amp circuits with great grounds (there is no such thing as a perfect ground).

No hiss in mine

One pair of M200's driving a pair of Onyx Rocket 750's ... no hiss, very clean and enjoyable.

Used to, but we moved a computer to a different circuit. No hiss since then on music setting (several months ago). I picked some trigger lines anyway. I just like having cool stuff. :p

NewBuyer, did you end up buying the M200s? As a prospective buyer I'm curious about your decision and the results?

I have "almost" bought them several times over the last couple of weeks, and each time at the last second, talked myself into thinking it over for another day or two!

A big concern of mine is that I only have two empty power sockets in the wall, and each of these monos will require its own socket. I would want to buy five of the monos for my system, so I don't know I would handle this issue, or how other people have handled this issue...

Also, the manual for these monos is very clear about the clearance for proper ventilation, yet I hear that people are stacking their monos in violation of these stated requirements in the manual. What's up with that?

Just a couple of my worries about the purchase... does anybody please have any thoughts or advice to share, about these specific purchase worries I'm having?

Many people use good quality power strips from companies like Tripp-Lite because they don't restrict current flow. Keep in mind that even if that duplex outlet were replaced with a quad, you are still connecting everything to one 15A circuit - same as if you picked up a multichannel amp and plugged it into a single outlet.

Outlaw has stated in the past that the M200 is designed to allow up to three amps to be safely stacked together, and I think many people have stacked as many as four (sets of 7 tend to end up in either a stack of 3 and a stack of 4 or a stack of 3 and two stacks of 2). Going beyond around three in a stack is actually more of an issue for structural strength than cooling, I believe - my pair of M200's run quite cool, but they are heavier than they look.

A third thought to help relieve some concern - there's always the 30-day return policy that will let you ship them back for only the cost of shipping if they don't fill your needs. I suspect they will, though - they're great little amps.

I've had a pair on a single strip ever since they first came out and 3 on the same strip for several months and never tripped anything. I forget exactly which power strip I have, but it's just a mid-level Circuit City one.

NewBuyer, I know exactly how you feel. Although, I've been given a reprieve on time to make a decision because I'm going to purchase the 990. When this new model pre/pro is finally available for purchase then I'll have to make a decision.

I think it comes down to the convenience of one box or the flexibility of 5 monos. If something happens to the 755 the whole system is down. All 5 M200s would have to break for the whole system to go down.

I know when I finally make my decision it will most likely be a win regardless of which way I go. In this case I don't think a bad decision can be made.

From everything I've read in magazines, review websites, and here in this forum, they're both excellent products. I'm just looking forward to the day I can hear it for myself.

Well now I have an additional concern!

I was just about to buy the M200's, and then I found this post from Steve at Outlaw Audio (I've copied it from the Sound and Vision Forums):


----------------------------
Here is what Outlaw said about the model 200. I asked them if the damping factor changes from class A/B to class G.

Hello Tom,

The 200's damping factor is greater than 80 from 20 Hz to 20k Hz. Whereas the damping factor is indicative of an amp's output impedance, I believe it remains constant regardless of power output. If you are looking for an amp with a high damping factor, our 755 and 770 amps have a damping factor of greater than 850 from 10 to 400 Hz. All three are great amps but I feel that the 755 or 770 will have better control of a speaker's woofers or mid-bass drivers given their high damping and low output impedance. Please let us know if you have any further questions.

Thanks and Regards,

Steve
------------------------------


This reply directly from Outlaw Audio makes me very nervous that the M200's may not be as worthy an amplifier as we originally believed. A damping factor of 80 seems like an extremely poor specification, especially for a monoblock (?)

There has been some discussion of this very topic in the forum before. You might be interested in soundhound's commpents in this thread as to why he feels that a damping factor of 80 presents no cause for concern.

Thanks gonk, that was an interesting older thread.

However, in the above email from Steve, we see that even Outlaw Audio themselves are expressing concern about the M200's not having best control over a speaker's woofers or mid-bass drivers, due to the M200's low 80 damping factor.

We can trust Steve at Outlaw Audio in his comments, yes?

Did you know that the effective damping factor “delivered” to your speakers is affected by the impedance of the speaker cables? Before I quibbled about 80+ versus 400, I’d make sure that the impedance between the amp and the driver was down to about 0.1 to 0.4 ohms round trip. Two ohms round trip impedance in speaker cables would lower the effective damping factor to a point where you wouldn’t have the “good control” you're seeking over your drivers even if your amp had a damping factor of 1,000,000.

i tend to agree with sh on the notion that damping factor is overrated. i can think of many more important things that qualify a good amp. though i cant defend the m200 from personal experience, most people that have them like them.

Guys, we see above that Outlaw Audio themselves are recommending one of their other amps, instead of the M200, because of the damping factor issue.

Am I the only one bothered by this?

Apparently so. My 200s push NHT speakers at very high levels with no problem.

I'm not bothered by it. Do some research on the subject and you will find that the difference between a damping factor of 80 and 800 is negligible.

Damping factor is one of those audiophile terms where a small grain of truth is surrounded by a large mass of hyperbole and misinformation. My all time favorite is skin effect though. The claims for skin effects are usually quite humorous.

I personally love my 5 M200's and consider them a very good product both in terms of sonics and bang-for-the-buck. In addtion they appear good enough to be a platform for aftermarket modification as seen HERE

i think the claims for skin effect are reasonable. i dont think that damping factor is useless, just overrated.

Well OK, I have now done what I consider to be quite a bit of research on the relative importance of damping factor in amps.

I now realize that a damping factor of 80 is just fine. In fact, it is a very good figure for an amp, especially for a monoblock.

I guess that I am just going to HAVE to buy some of these amps!

if you are unhappy with them, feel free to give them to me.