Good / Bad designs of both exist. It may not be easy to compare, though since speakers won't be best electrical match for both at the same time.
Best SS designs tolerate some reactive loads better than tubes.
So, if you compare 'best-to-best', you may end up with a tube amp and a certain type of speaker...maybe a single driver, while if you audition a SS amp, you'll find a better speaker.
So, If you're thinking of using a reference pair of speakers to just go thru amps until you find the 'best', forgetit.
Comparing 'best', again, it may BE impossible to tell the difference between tubes and SS in many cases and when using synergistic components. Should that be a surprise? |
MrTennis,
As a long time Magnepan guy, part of your issue with the 1.6s may be more setup than the speaker itself.
At one point I was tweaking the toe every couple days. Bad image here or too bright or whatever.
Finally, in reading around, I found out that Magnepan SWAPPED SIDES on me in the mid-90s. Yep, you are probably listening to the mylar side, with the connection plate and fuse in BACK where you can't see it. You may even have the tweeters out. I think that's what the 'book' calls for. My MG-1s were mylar back and it never occurred to me that Magnepan changed that......My 1.6s now remind me of my old speakers, but MORE in every way....if that makes sense?
Well, ForGet It.
Just rotate your panels IN PLACE. Put the pole piece facing you, the listener and the tweeters 'in'.
My brightness disappeared due to my now crossing the speakers axis behind my sitting position. I couldn't do this before without some funny (not funny, really) image artifacts or even a 'hole' in the center. Now, I have a much better image, no comb effects, smoother HF response, the resistors which I had on the table threatening to install are now put away and the sweet spot is MUCH wider.
Try it and get back to me.....pm if ya' gotta. |
The difference between 'old' Maggies and 'new' is the difference between pole piece forward and mylar forward.
The old way, IMO was better. My original MG-1s had a character and feel about them not equaled by my 1.6s, until I did a rotate-in-place.
Anyone having 'brightness' or treble problems with Magnepan should try a simple rotate in place test, give 'em a few minutes and adjust to preference. Maybe even give it a day or more.
When I did the rotate thing, the change was so startling that I knew they'd stay that way. Had more of the character of the MG-1 without the heat of the 1.6 as well as a fuller center image and simply a wider 'listenable' seating area.
Cost? just a few minutes and the electricity you were going to use anyway, to listen to that new album. |
Atmo::
When I have a mosfet device under test, what parameter am I looking for?
Under what conditions will I be able to measure this parameter?
The 'capacitive' element of a mosfet would be 2 conductors, separated by an insulator. Now, the drain, source and gate will all have resistence associated with them and the gate oxide, usually pretty thin.....on the order of angstroms, is capacitive but how much? in the nano farads, for sure.
Their doesn't appear to be much capacitance between source and drain since they are both just differently doped regions of the substrate, except in International Rectifier HexFet devices.....(of which Carver was a big fan)
Even the devices I'm used to building, in which the drain is on the bottom of the device have no capacitive elements, again, except the gate oxide.
just curious...........Instead of magfan, you can call me FabGuy. |
http://www.irf.com/technical-info/appnotes/mosfet.pdf
Capacitive turnon / turnoff delay.....that seems to be the issue.....
However, In a device with VERY thin gate ox......How much capactance are we actually talking about?
I never even heard the test guys talk about this..... |
I'm not a probe guy. i spent about 30 years making both ICs and discrete.
I am most familiar with probe parametrics as they apply to my area of specialty.
As for probers, I know they weren't HP. The last ones I remember were some kind of european 4 station from one central computer/data gatherer. Individual histograms of each wafer were stored for later analysis...patterns of failure and such. I avoided probe....looked too much like work.
I am much more comfortable with diffusion / implant / metalization and was very good at metrology. Nanometrics equipement, surface profile stuff and elipsometer along with various 4pt probe and specialty tools. |
The devices made by IR are 100% not symmetrical MOSFETs. The gate and source are on the top of the device, while the drain is the bottom of the wafer, which, while I can't discuss fabrication details, has an ohmic contact with the package.
So, gate/source is very low cap while the drain is many microns away, so should have much higher capacitance.
No effort at all for a groove-type symmetry. This is strictly a planar device.
Rleff (nice, diffusion oriented name).....I'm not knowledgable about probe enough to know who makes what. The last HP stuff I saw in a test area were the frequency meters used to tune quartz crystal oscillators. This was no later than about '80. |
So many possible responses.
Isn't it true that when connecting to the various taps on a transformer that you are using more or fewer windings? Won't that change sound more than the load variations to a SS amp?
I like the talk of sensitivity and efficiency as different things. Also on the plate is impedance...and not just a single nominal number, but the range, along with min / max for any given speaker.
Than again, nobody has yet mentioned phase. I am told that Harbeth makes LS 3/5a type speakers and though they are about 83db sensitive, make a wonderful match for tube amps. Benign phase and moderate impedance range are key.
My panels should work with tubes, as well. Reasonably flat impedance curve and no wacky phase problems.
Naw, I think the concept at least is pretty simple. Compatibility / synergy can be chosen electrically. Magic happens when you get it REALLY right. It shouldn't take a lot of money for a good, basic, solid, good sounding simple system. No need to spend a bundle on cables, either.
Again, damping has come up. And nobody has mentioned speaker 'Q'. What role does the design of the speaker have in all this? Can't a critically damped speaker produce fine bass in an 0 damping factor system? I suspect so.
You don't need a DF of 10,000 to get good bass 'control', which is one of the red herrings of audio. A speaker with 'Q'=1.25 will be sloppy almost no matter WHAT you do. |
Compare the 'best' with the 'best' and see....and not just the amp, but an entire system.
Source, pre/amp and speakers.
I'll bet the BEST of each when properly matched have much more in common than differences. Some of these esoteric differences which I see bandied about, may be unheard in a 'best' system.
Even the best tube amps will fall flat with highly reactive loads of huge impedance swings, while SS has its own limits, maybe when dealing with single driver / full range speakers. |
I suspect, but don't know that the differences between current source and voltage source amps....and the speakers they go BEST with would preclude a single system with 'plug in the amp' testing possible....at the highest level.
As near as I understand it.....Carver nulled the amps by somehow comparing thru a single speaker. When the speaker made NO sound....or some large value 'down', they amps were producing the SAME sound. The louder the speaker, the greater the difference between amps. This is the source of the 't-mod' which was part of my now ancient Carver Cube, the M-400t.
I don't remember the exact numbers, but just for example, when the speaker being used was say......nulled to -60db, you could say they were the 'same' to 1 part in 10,000 or some such.
ONE possible flaw in this ointment is that of the speaker used. If it was a highly reactive load, the tube amp would not be at its 'best' while a speaker of the single driver/full range persuasion may put the SS at a disadvantage. I doubt there is an 'easy' or even 'best' answer here.
Buy / run / listen to, whatever floats your boat. Play safe, eat slowly and chew well. don't stay out late and respect your elders. |
This thread is one of those no-win threads.
Like a 'what is best' thread. No single answer.
I'll probably never own a system better than I've got now, unless I win the lottery or somebody tosses me the key and alarm codes to the local fantasy land.
Just trying inject some levity.....the opposite of gravity. It was getting too serious.
And seriously, don't you think I've got a reasonable viewpoint?
Enjoy! |
