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In Reply to: RE: More Testing Of Tubes (Mastersound) Vs Transistors (Jungson) posted by Pat D on May 29, 2007 at 21:53:48
PD - You speculate that the slight harshness and congestion at louder levels with the 200 watt JungSon amplifier has something to do with amplifier clipping. But in fact, there are a number of things it could be. It is quite likely it is simply the result of driving a small two way speaker to loud levels. I won't bore you with other possible explanations
You got it Pat. So far, the usual suspects here all look to what they want see, some form of fault in the amplification. The BJH case was laughably easy to diagnose, but this one has the required lack of data...gulp..measurements. However, we do have something to work with.
The link below shows all the data required by an audiophile. Unfortunately, it only told me that they have no clue about crossovers (gotta love the 1st order 6db - applied to a 2nd order bandpass. Gee I wonder what acoustic slope we have there? No compensation?) and what drivers we may be dealing with. The tweeter appears to be a SS2905/9500.
They have most likely just put a cap on it for an electrical 6db roll off. XO frequency is by law not mentioned, but IIRC from a "review" it is somewhere in the 3k range. Which of course means that at high drive levels (as can be obtained form a 200w rms amp) we have high levels of IMD & THD from the tweeters low end creating hash at HF (look at the rising 3rd, 4th and 5th order at mild drive levels). Add this on top of the breakup hash from the insufficiently suppressed woofer top end and we have a delicious audiophile recipe of distortion.
Yeah, that ought to lead to some harshness.
cheers,
AJThe threshold for disproving something is higher than the threshold for saying it, which is a recipe for the accumulation of bullshit - Softky
Follow Ups:
Above 2khz the F3 of this tweeter is lower than -60db. At 90db this is likely inaudible. The F4 and F5 are also quite low at this level. What is your point? There is nothing unusual about this tweeter's distortion and in fact it is better than most but you don't bother to point this out in your dubious attempt to discredit this speaker. For sure the crossover point is above 2Khz so as you can see the distortion is overall lower above this frequency. Also, this driver has excellent settling times, meaning extremely clean waterfall plots.
Ah yes! One can't reduce speculations to reality without good information.
Your technical knowledge far exceeds mine. I'm not really sure what that graph is saying as it's not labeled.
I haven't seen anything to suggest what the crossover regions might be. With a 6 dB per octave slope, I would guess fairly high due to power handling considerations. My impression is that Tom doesn't listen much at really high levels--I don't either, but I know how loud I listen within the limits of my RS 33-2050. I once had some two-way + passive radiator speakers (Kef 104, later modded to 104aB) which crossed over to the tweeter at 3 kHz (but at 18 dB per octave). The response was quite even in the listening window but the off axis dispersion from 1-2.5 kHz wasn't very even. They had a great impulse response, too. (Richard C. Heyser reviewed them for Audio magazine). With careful set up, given a lot of room well away from the walls, and at a reasonable distance, they could sound very good. Even Paul Barton said that they could sound good in an LEDE room. In a big room in the far field, they could sound rather bassy due to the depressed power response in the presence region.
Now, a speaker with a highish crossover relative to the mid-woofer will have what John Atkinson calls an off axis "flare" around the crossover because the tweeter's dispersion is so much wider than that of the woofer in that region. That could cause harshness. Nothing to do with amplifier clipping. Now, if the Mastersound 845 has a dip in the FR around there with the Aliante PF Ones (which would not occur with an amp with a low output impedance), that might improve the sound--maybe his speakers do sound better with his tube amp.
I wasn't in the mood at the time for a long explanation to Tom, but that's how a tube amp *might* work better in one respect with those speakers.
I was amused that the Aliante site waxes eloquent about the expensive copper used for the phase plug! I found a couple of subjective reviews of the Aliante PF One, one by the late Lars Fredell (who seemed like a very nice guy--he emailed me once about absolute polarity) who went on at some length about by the way the speaker handled sibilants, the other by Stephen R. Rochlin, who also seems like a very nice guy--judging from his posts here. I didn't note anything about the crossover point, though, and nothing technical beyond the Aliante literature. Neither of them seemed bothered by anything the speaker did with SS amps.
____________________________________________________
"Opposition brings concord. Out of discord comes the fairest harmony."
------Heraclitus of Ephesis (fl. 504-500 BC), trans. Wheelwright.
I recently bought a used Jungson D-200IA for a secondary system, and I have to say, so far I am very impressed. It appears to be built like an absolute tank, and the sound has much more authority and resolution than the NAD it replaces. I switched my primary setup over to an NHT Xd system, so I no longer have (or need) the exotic amps I used to own for that system. Too bad, as I would have liked to have heard this thing up against the Threshold and Pass amps I used to own...
J
Pat,
I agree that Lars Fredell & Stephen R. Rochlin seem to be very nice gentlemen indeed. One time at TAKE 5 Audio in Connecticut I spoke with a couple of fellow audiophiles in the store. After they left the saleperson told me that was Sam Tellig & Lars Fredell! But I digress...
I think it's joke that someone (not you) would try to account for the harshness I heard by based on info for a stock SCANSPEAK D2905 driver. Stephen R. Rochlin states in his review of the Aliante Pinafarina One "ScanSpeak and Seas, long considered two of the best European specialists, produce the drivers for the Aliante line to their specifications." Seems to me that a stock driver and one made to Aliante's specifications could, would & should measure/sound differently, no?
Also in regards to the comments about a 6dB/octave crossover some others here are making, Stephen R. Rochlin also said in the same review: "The ScanSpeak-produced 28mm silk soft dome tweeter is carefully hand made and manually coated in different steps to achieve proper damping to ensure fast response while also reducing possible distortion. When a manufacturer can ensure such high quality, they can also take advantage of using a more gentle, 6dB/octave (1st order) crossover. While the pros and cons of using such a crossover can be debated, it most certainly means that very few parts are needed, thereby less in the signal's path."
Both quotes were taken from this review:
http://www.enjoythemusic.com/superioraudio/equipment/0903/aliante1.htm
I have to admit I love it when people comment on components they've never heard! Sort of like judging what kind of lover Halle Berry is from her picture, no? I wonder how many people who commented negatively about the Aliantes or Mastersound have heard either of these components? I know specs are impossible to get on either.
Of course you were 100% correct Pat when you said Neither Lars Fredell nor Stephen R. Rochlin seemed bothered by anything the Aliante did with SS amps. Truth be told after a weeks continued usage of the JungSon D-200IA I am no longer hearing the harshness & congestion on loud musical peaks! So it seems all previous suggestions by solid state proponents were in error. Of course I leave the JungSon powered up with volume set at 0 all the time, so perhaps it just needed to warm up? I honestly don't know. I'll be listening to the JungSon exclusively for one more week before comparing it to the Mastersound again. But the reality is this amp is sounding better now that it remains powered up and it's starting to really grow on me. I like this amp... A LOT!
Thetubeguy1954
PD - Your technical knowledge far exceeds mine
Doubtful. Of course, *zero* technical knowledge doesn't seem to hinder posts and "tests" in these parts, does it? ;-)
PD - I'm not really sure what that graph is saying as it's not labeled.
Sorry, posted in haste this a.m.
That's a Scan Speak 2905/9500 tweeter like the one used in the amplifier "test", distortion at 90db/1m drive level. Raw driver.
F3 is 3rd harmonic, F5 fifth, etc. Site link below if you ever get the urge to build your own and need some driver data - or just feel the need to stare at graphs like "objectivists" like to do, while others listen to music and perform "tests".
The speakers being used will have massive levels of intermodulation distortion at anywhere near 200W input, way before the amp is clipping, so the "test" is useless for this purpose.
PD - Now, a speaker with a highish crossover relative to the mid-woofer will have what John Atkinson calls an off axis "flare" around the crossover because the tweeter's dispersion is so much wider than that of the woofer in that region. That could cause harshness.
Yes, the DI (directivity index) of this little box with uncorrelated drivers vertically stacked on a flat baffle will be a nightmare. But this "flare" would result in more "forwardness" than harshness. An imbalance in tone, etc rather than "harsh". Again, the "harsh" comes from the HF "hash" as the woofer cones breakup is woefully unsuppressed by the 6db electrical filter added to the drivers natural roll off, piled on top of the large amounts of HF hash from IM generated at the bottom end of both woofer and tweeter drivers.
The eq curve being generated by the Aliantes impedance roller coaster and the tube amps high impedance output is anyone's guess, since measurements will never be applied. Plus, measurements don't matter, lest we forget ;-).
cheers,
AJ
The threshold for disproving something is higher than the threshold for saying it, which is a recipe for the accumulation of bullshit - Softky
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