How about a turntable which has all of its design criteria in the public domain? The Teres turntables were developed by an international consortium of audiophiles on the internet. All the engineering data and parts specs are available on the web. Also, the participants and designers names and email addresses are on the web. No matter what may happen to the company(which I believe is growing and will be around), all parts, dimensions and materials are available from the vendor companies, and even suitable alternative parts may be substituted, when you have the specs. The platter, bearing, and plinth are virtually bulletproof, and the motor is in a separate housing. I doubt Maxon swiss motors is going out of business anytime soon, but even if they did, you could even substitute any outboard drive system alongside the turntable and just swap pulleys. The main parts of the table(platter, bearing, plinth) are stand-alone, and will never wear out. The only thing that might wear out is the motor/controller. Since they are outboard, you could even buy a few of them, and keep them as spares. The whole motor/controller/pulley/housing system is only about $400 and you could keep a couple of them in a shoebox.
The Teres tables are robust and very good sounding. They are overbuilt and simple. All parts and specs are available to you, no matter what would happen to the company. No secrets. This is about as safe as you could get. And the only part that is subject to failure is sourced from a very major industrial motor company which is much more likely to be here than any turntable company 25 years from now. And even if there was a problem with that, many outboard motor units from people like Walker, VPI, Verdier, or any standalone motor/controller unit can be substituted easily, with no disassembly. Or you could get a cache of spare motor units. I think that having access to all parts easily is better than depending upon the solvency of any audio company.
They will accept any arm. They have no springs to sag or go bad. No air bladder suspensions to leak. No mats to deteriorate or degrade. The belt is made of silk cord that is available from any sewing or beading store, so you don't have to stockpile rubber belts that may deteriorate with age either.
Basically, you have a turntable that has just about no breakable/wearable parts, and a separate motor housing that has all of the breakable/wearable items inside it, by itself. You can stockpile these or source the contents yourself any time you want. I'm sure Chris will give you a complete parts list of every single component in the system, along with their vendors, if you want a compiled list, so you don't have to make it yourself off the internet. He can also sell you separate replacement motors, control boards, or whatever you want.
I think it is best to be in control of your own destiny, instead of relying on any company being in business.
The Teres turntables are very reasonably priced and factory-direct. The performance is as good or better than most tables priced far higher. I'd pick my Teres over any table that has been mentioned in this thread so far.
So, there's a different angle for you to consider. |
Raul,upon reading the same Stereophile article from the 1994 archives, I found this rebuttal letter at the end of the article regarding frequency response variations of tube amplifiers with regard to speaker impedance changes and damping factors.
From the Stereophile archives
"A letter in response appeared in April 1994 (Vol.17 No.4):
Thomas J. Norton's "Questions of Impedance Interaction" in January (p.109) showed that a ghostly echo of a loudspeaker's impedance modulus can be imposed on its frequency response by virtue of an amplifier's source impedance acting as the top limb of a potential divider. Mr. Norton illustrated the effect with some specific graphics, but the data can be usefully generalized by means of a simple rule arising from the ohmic arithmetic.
Assuming a worst-case situation of very large impedance undulations, with, for instance, an LF peak reaching 10 times the value of that characterizing the lower-mid region, the rule runs as follows: To confine frequency-response changes within an amplitude band of 1dB, the amplifier's source impedance (plus the resistance of its connecting cable) must be less than an eighth of the speaker's impedance at the latter's lowest point, and less than a sixteenth for a band of 0.5dB.
These criteria also satisfy damping requirements for practical purposes, since the resistance of a speaker's voice-coil is effectively in series with the amplifier feed, so that once the latter falls below about one quarter of the coil resistance, there can be no worthwhile improvement. Perceived changes in bass "softness" between transistor and tube amplifiers are thus more likely to be due to LF impedance "response ghosts" than to the damping-factor, as such. Huge ratios for this parameter make impressive reading in technical specifications (like ultra-low distortion figures), but are so far along the relevant asymptotic curve as to be useless for audio purposes..John Crabbe, Todmorden, Lancashire, England "
End of Stereophile excerpt.
So, as you can see, there is no consensus that this lower damping factor in certain tube amps with low/no negative feedback in conjunction with certain speakers will actually have the frequency response effects that you refer to as "equalizers". As long as the damping factor remains above 4, then the "equalizer effects" that you refer to are insignificant according to Mr. Crabbe(and others). Many tube amplifiers have output impedances of less than 2 ohms, and many "tube friendly" speakers have impedance curves which remain at(or above) 8 ohms, so this can provide the necessary damping factors of >4 that are required for linear response within about 1 db.
Additionally, it has been known for many years that adding negative feedback to improve damping factor and reduce measured distortion(which is common in both tube amps and SS amps) can be deleterious to the musical sound quality. When applying negative feedback to a sinewave test tone, it shows reduced measured distortion and also improves damping factor. But when playing music which is non-constant, the feedback loop actually can increase music distortion because the feedback added is actually phase shifted(due to the length of the feedback loop), and adds feedback from a previously played part of the signal to an upcoming part of the signal, thus making a big mess. Now, to be fair, engineers have used short feedback loops and other techniques to minimize this problem, but it still can and does exist. This is why some amp makers are adamant about making "no feedback" amplifiers.
So yes, I understand your concerns about the tube amps becoming "equalizers" in theory, but in practice(with a correctly matched system) this concern is not founded in reality. In a poorly matched system, this could be a problem, but all kinds of problems can arise in a poorly matched system. Your "broad brush" application of this concept to all tube amp/speaker systems is misleading at the very least, and disingenuous at worst.
While SS amps with negative feedback and high damping factors may have certain good aspects, there are also downsides to that type of design, as I have just described. Many SS amp makers make strong efforts to minimize or even eliminate feedback in their amps, so that these problems do not noticeably degrade their amps' performance. I agree that while the naturally low output impedance of SS amps, and even the use of negative feedback, can provide a very impressive damping factor number, the overall benefits of this become "asymptotically small" after a small basic damping factor number(>4) is achieved. The main benefit comes from being able to choose from a wider range of speakers which may exhibit low nominal impedances and low impedance swings that may strain amps with higher output impedances. It can be a useful thing in some circumstances. But, matching the amp to the speaker can and does make the difference, and as long as the user observes proper matching, this "equalizer" phenomenon is not a real concern.
As we now see, there are plusses and minuses to various types of designs, and it is the user's responsibility to configure his system to the best effect.
Regards, and enjoy the music.
TWL
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Raul, I do agree that there are some favorable characteristics to both SS and tube designs.
However, it appears that you are attempting to engage in some kind of "specs race" between SS and tube amps. Distortion Specs are only useful in some regards, and are not indicators of performance in a music system. The methods used to measure them are not the same as the intended use of musical playing, and therefore may have little or no bearing on the actual musical performance of the amplifier. Static sine-wave distortion measurements into a dummy load are not even close to the way an amp produces music. Most informed users do not rely on these specifications. The ear can hear distortions produced by a design that do not show up in any measurement protocol.
Regarding "complementary transistors", they are only applicable in Class AB or B amplifiers(push-pull), which require switching, phase-splitting, or both, and are not the equal of true Class A design(no phase-splitting or switching) for musical reproduction. But I agree that complementary Class AB is nice to use when you need a high power amp that cannot run totally in Class A all the time, for use with certain difficult speakers. But it is obvious that virtually all Class AB SS amp makers bias them as high as possible, to keep the amp in Class A as much as possible. This is simply a "de facto" example that any kind of Class B(complementary or not) cannot compete with Class A sonics of a similar quality level amplifier(maybe even from the same manufacturer). They just do this switching to Class B so they can output more power without as much wasted heat. Not for better sonic performance than Class A.
Regarding your comments on "unwanted harmonic content", which I suppose means "harmonic distortion", you only have to look at harmonic distortion curves of various amplifier designs to see that SS amplifiers have relatively low amplitude harmonic distortion characteristics, but have them all the way up the spectrum, and have them primarily in odd-order content, which makes them much more objectionable to the ear, and therefore they have to be lower to be even listenable. Tube amps, on the other hand, especially Single-Ended Triode amps, have a somewhat higher amplitude harmonic distortion curve, but it is located primarily(almost completely with SET) at the 2nd harmonic interval, and is almost all even-order distortion which is easier on the ear, and also easier to deal with by other aspects of design. Push-pull tube amps are not as good in this regard as SET, and suffer from both odd and even order harmonic distortion, as well as the phase-splitting and complementary amplification things. But they can be good sounding amps nonetheless, if they are designed and built well(typically with some negative feedback that was well applied).
Regarding your discussion about output transformers, this is the crux of your previous discussion that included output impedance of tube amps and their performance with reactive speakers. The tubes have higher output impedances than transistors, and usually must have impedance-matching output transformers to achieve a low enough output impedance to drive a speaker load. This is well-known. I agree that there are problems associated with output transformers. However, very good output transformers achieve a very high level of performance, and mitigate the problems to a large degree. OTL and ZOTL can eliminate these output transformers, but traditional OTL must resort to parallel-ganging of the output tubes to reduce the output impedance to a useful level(which is still usually a bit too high, but works), and only ZOTL allows the use of true SET Class A single-tube output, with impedance matching to the speaker that is under 2 ohms,no output transformers, and devoid of the typical transformer artifacts. As you know, this is a unique circuit from David Berning, and it the circuit used in my personal amplifier. The distortion from this(my personal) amplifier has total harmonic distortion of much less than 2% in the audio spectrum and the predominating location is at the 2nd harmonic(with much much less in the rest of the spectrum). Output impedance with 0 feedback is under 1.8 ohms. The circuit is true Class A(no phase split) and has a single output triode per channel, which negates any need for any "complementary devices". Bandwidth extends to 500khz. It can produce a square-wave anywhere in the audio range. True full-power bandwith is produced down to 2Hz(where a coupling cap intercedes to avoid DC), and this produces very prodigious and fast bass response. Signal-to-noise ratio is better than -100db(quieter than most SS amps). Supersonic(RF)frequencies are used to heat the tubes, for heater noise elimination and long tube life. The amp is 12vdc powered to eliminate line noise. It has choke-loading for improved linearity. Super short signal path. Ultrahigh-speed switching power supply that is very stiff. Overall, this amp is about the most advanced and most musical amplifier that I have ever heard or seen, and it is a tube amp. I realize that specs are not the answer, as I mentioned earlier, but if you want some specs, there they are.
If you want to quibble about the 2% total harmonic distortion spec on my amp, then it would be useful to note that the single-driver speakers that I use have a similar 2% harmonic distortion profile at the 2nd harmonic primarily, and the judicious connection of the speakers at 180 degree phase angle to the amp outputs cancels much of the overall system harmonic distortion, and results in an overall system distortion much lower than any competing SS or tube amp with multi-driver speakers( which have wide ranging additive distortion profiles and cannot benefit from this happy matching). See the articles by amp designer Eduard de Lima on SET amps and single-driver loudspeakers, available with a web search.
I have no "axe to grind" against SS amps in general, and there can be some very nice SS amps. I have owned and heard many. My main purpose for my posting here, is to rebut the premise that you have made, which states that tube amps cannot be serious musical amplifiers. I hope I have done that. Nothing is perfect. Bliss is in the ears of the beholder. |
Raul, anyone who thinks that the location and order of harmonic distortion is "not matters", has no clue of what harmonic distortion is, nor how it affects a musical presentation. Please bone up on it, and try again.
Regarding the 1.8 ohm output impedance of my amplifier, I use 8 ohm speakers which provides a damping factor greater than 4, so it works as well for speaker control and frequency response as any SS amp with any kind of damping factor. Any damping factor greater than 4 is immaterial and makes no discernable difference in the amplifier's ability to control the speaker. The frequency response of my amp is totally unaffected by speaker reactance in my particular system, so it doesn't matter what Stereophile says about amps with 3 ohm output impedance and poorly designed highly reactive speakers. If you notice the Stereophile chart, the impedance peaks that are imposed on the very poor example they chose to use, are at the resonant freq.(F3) of the driver, and at the cabinet tuning point. In the case of my system, my frequency response starts above both of those points, and have no effect in my system. But since you are not a speaker designer(and apparently not an amp designer either) I wouldn't expect you to know about that, any more than you know about the subject we are discussing.
The "very high output impedance" as you put it, has no bearing at all on anything, until you connect a speaker to it. That is when the damping factor is defined, and not until then. If I attached a speaker with a 0.1 ohm load to a SS amp with a 0.05 ohm output impedance, then the damping factor of the SS amp would suck(with that speaker). If you actually knew anything about this parameter, then you would not make statements such as you do.
I actually think that you know very little about audio. You read a few things, and think you know what you are talking about. Your statements give you away.
By the way, we are all still waiting for you to reveal the contents of your "highly musical" solid state system that will be revealing of the "true music" that you think we all are lacking in our systems.
You know, not only are you seriously lacking in audio knowledge, but you are very abrasive, rude, and arrogant. You seem to think that it is ok to ignore anyone else's points, can never debate an opposing position with facts, and simply repeat your own flawed opinions, in the attempt to look important. This is really sad. I like to engage in vigorous audio debate, but I prefer to do so with someone who knows what he is talking about. Unfortunately, you do not.
I'd suggest quite a bit more study before engaging any serious audiophiles here again. You really do need it. |
Here is a very recent article "cut and pasted" from the Audioholics website regarding this very matter.
Damping Factor: Effects On System Response
Monday, August 30 2004
Damping Factor: Effects On System Response
Analysis
Several things are apparent from this table. First and foremost, any notion of severe overhang or extended "time amplitude envelopes) resulting from low damping factors simple does not exist. We see, at most, a doubling of decay time (this doubling is true no matter what criteria is selected for decay time). The figure we see here of 70 milliseconds is well over an order of magnitude lower than that suggested by one person, and this represents what I think we all agree is an absolute worst-case scenario of a damping factor of 1.
Secondly, the effects of this loss of damping on system frequency response is non-existent in most cases, and minimal in all but the worst case scenario. Using the criteria that 0.1 dB is the smallest audible peak, the data in the table suggests that any damping factor over 10 is going to result in inaudible differences between that and one equal to infinity. It's highly doubtful that a response peak of 1/3 dB is going to be identifiable reliably, thus extending the limit another factor of two lower to a damping factor of 5.
All this is well and good, but the argument suggesting that these minute changes may be audible suffers from even more fatal flaws. The differences that we see in figures up to the point where the damping factor is less than 10 are far less than the variations seen in normal driver-to-driver parameters in single-lot productions. Even those manufacturers who deliberately sort and match drivers are not likely to match a figure to better than 5%, and those numbers will swamp any differences in damping factor greater than 20.
Further, the performance of drivers and systems is dependent upon temperature, humidity and barometric pressure, and those environmental variables will introduce performance changes on the order of those presented by damping factors of 20 or less. And we have completely ignored the effects presented by the crossover and lead resistances, which will be a constant in any of these figures, and further diminish the effects of non-zero source resistance.
Frequency-Dependent Attenuation
The analysis thus far deals with one very specific and narrow aspect of the effects of non-zero source resistance: damping or the dissipation and control of energy stored in the mechanical resonance of loudspeakers. This is not to suggest that there is no effect due to amplifier output resistance.
Another mechanism that most certainly can have measurable and audible effects are response errors due to the frequency dependent impedance load presented by the speaker. The higher the output resistance of the source, the greater the magnitude of the response deviations. The attenuation can be approximated given the source resistance and impedance vs. frequency:
where is the gain or loss due to attenuation, is the amplifier source resistance, and is the frequency dependent loudspeaker impedance.
As a means of comparison, lets reexamine the effects of non-zero source resistance on a typical speaker whose impedance varies from a low of 6W to a high of 40W .
Damping
factor
RG
GdB(MIN)
GdB(MAX)
GdB(ERROR)
¥
0 W
0 dB
0 dB
0 dB
2000
0.004
-0.006
-0.001
±0.003
1000
0.008
-0.012
-0.002
±0.005
500
0.016
-0.023
-0.003
±0.01
200
0.04
-0.058
-0.009
±0.025
100
0.08
-0.115
-0.017
±0.049
50
0.16
-0.229
-0.035
±0.098
20
0.4
-0.561
-0.086
±0.23
10
0.8
-1.087
-0.172
±0.46
5
1.6
-2.053
-0.341
±0.86
2
4
-4.437
-0.828
±1.8
1
8
-7.360
-1.584
±2.9
As before, the first column shows the nominal 8W damping factor, the second shows the corresponding output resistance of the amplifier. The second and third columns show the minimum and maximum attenuation due to the amplifiers source resistance, and the last column illustrates the resulting deviation in the frequency response caused by the output resistance.
What can be seen from this analysis is that the frequency dependent attenuation due to the amplifiers output resistance is more significant than the effects on system damping. More importantly, these effects should not be confused with damping effects, as they represent two different mechanisms.
However, these data do not support the assertion often made for the advantages of extremely high damping factors. Even given, again, the very conservative argument that ±0.1 dB deviation in frequency response is audible, that still suggests that damping factors in excess of 50 will not lead to audible improvements, all else being equal. And, as before, these deviations must be considered in the context of normal response variations due to manufacturing tolerances and environmental changes.
Conclusions
There may be audible differences that are caused by non-zero source resistance. However, this analysis and any mode of measurement and listening demonstrates conclusively that it is not due to the changes in damping the motion of the cone at the point where it's at it's most uncontrolled: system resonances. Even considering the substantially larger response variations resulting from the non-flat impedance vs. frequency function of most loudspeakers, the magnitude of the problem simply is not what is claimed.
End
As you can see from these calclulations, a damping factor of 5(1.6ohms/8ohm spkr) provides 0.86db variation in frequency response as a maximum. This falls well within a +/-1db spec. It is inside the +/- tolerance of any loudspeaker, and certainly far inside the tolerances of any listening room. Other factors in the listening system/room will far outweigh this factor, thus making it insignificant in magnitude, even in a low damping case such as 5.
How anyone can make a case that tube amps are "equalizers" from this performance data, is beyond me. I certainly hope that this puts this matter to rest. |
And my last post was premised on the damping data alone, and did not even take into account the other important factors that may play into this matter. |
Suttlaw, that Rottweiler "tweak" can go anywhere he wants to! :^)
Typically, he goes right next to the listening chair, since he likes to be close to his "Dad". |
Gregadd, those frqequency extreme and transient softness issues are also output transformer related. Not necessarily related to tube response. Tubes can provide very wide frequency extremes, and fast speed, when done properly. |
Here's a link to the entire article. http://www.audioholics.com/techtips/audioprinciples/amplifiers/dampingfactor.phpI copied the entire 2nd page in my previous post, which related to the issue we were discussing. However, on the first page there is more info regarding the misconceptions of large amounts of overhang or time-delay that has commonly been attributed to tube amplifiers, and found to be not true by these measured results from Audioholics. |
To me, the key here is not whether there may be some slight affects to the amplifer based on speaker reactances, but whether these small effects could even be actually audible, given wider range tolerances in many other parts of the sytem context.
As Audioholics points out, even normal changes in temp, humidity, and barometric pressure in the room makes more of a difference than some of these issues.
Additionally, practically no speaker made is going to have an "in-room" response of within 1db, so all of this brouhaha is virtually immaterial anyway. This output impedance/speaker reactance parameter is nowhere near to defining the outer envelope of system frequency response +/- tolerances in anyone's system. If we want to improve overall system frequency response, we can look elsewhere for the culprit.
If we want to really look for the differences in sound between tube amps and solid state amps, I think it is in the tone. The even-order harmonic distortion profile of certain tube amps(SET) have this profile when playing, not just when clipping. SS amps with wide-rangeing odd-order harmonic distortion profile have this profile when playing, and not just when clipping, too. Since odd-order harmonic distortions are not found in natural musical presentations, even very small amounts can be detected by the ear, and found to be an unconvincing reproduction. There may be other factors too, but I think that this is at the basis of it. Simply my opinion.
Before we jump on the bandwagon about this, is should be noted that push-pull tube amps are also rife with odd-order harmonic distortion, and so are multi-driver loudspeakers with crossovers. So it may not be(is not) just the amp that is causing this in most systems.
I find it interesting that some people want to focus in on a single parameter to back-up their prejudices about tube amps, when it is entirely possible, and even probable that inherent odd-order distortions in transistor amps/multi-driver speakers may be causing far worse sonic problems to real music listening, and they don't even know it. In fact, I find it rather humorous that as they chase a "spec" or "measurement" around, the sonic realism that is provided by a device that "specs worse", and therefore is "not acceptable", could actually be the very thing that they need to give them the convincing musical reproduction that they seek.
Sometimes I just have to wonder. |
Raul, I would refer you to the David Berning website, in the White Papers section, where amplifier transfer characteristics are discussed.
You may know that the "load line" of a given amplification device in an amplifier defines how it responds to the loads presented to it by the speaker(load) and how well it will control it directly and without feedback.
In my Berning amplifier, the load line is about 1.8 ohms, and it operates with no feedback, and is globally DC stabilized(something you seemed to think could only be in SS amps, and not be achieved with tube circuits, but is a feature of the David Berning ZOTL circuit). However, by using the much larger "effective turns ratio" that is provided by the unique ZOTL impedance conversion circuit, much more effective control of the speaker load by the triode is possible, than would ever be possible using any output transformer or traditional OTL ciruits. In fact, with the load line that is in my amplifier, according to the David Berning "White Paper",
"In an audio application, the tube behaves as if it is driving a 4k ohm speaker (the impedance conversion ratio goes as the square of the turns ratio), and the speaker acts and sounds as if it is being driven by a 0.6 ohm triode."
And this, with the use of ZERO FEEDBACK. The natural load line of the triode is sufficient to produce this, when using the ZOTL impedance converter design. So that all the linear transfer characteristics of the triode are preserved, and full control of the load is realized, while exceeding the capability(and eliminating any of the drawbacks) of any output transformers.
So, as you can see, the use of this design allows both a low output impedance AND zero feedback, and at the same time eliminates all the saturation problems and parasitic capacitances of typical output transformers in audio applications, and still allows the use of a single triode(no parallel tubes like traditional OTL) to control the speaker accurately and in conditions of shifting speaker impedances(within reason), based on its inherent transfer characteristics(load line)in conjunction with the Berning ZOTL impedance converter.
While David does give credence to your concerns about shifting impedances causing frequency response problems in certain amplifiers, it is shown that this amplifier circuit is not adversely affected by the things that you mention, and the load lines in the ZOTL circuit are very close to what would be expected from some MOSFET transistor amplifiers(without feedback). However, the sonic attributes of the triodes are preserved, and gives what might be called "the best of both worlds", as the control and speed are very much like solid state, and the transparency, tone, and harmonic qualities are all tube.
So, here we have a tube amp with a single output triode(per channel), no audio output transformers, no feedback, an effective output impedance of about 0.6 ohms, DC coupled and global DC stabilization, bandwith from 2Hz - 500kHz, high-speed switching power supply, RF-frequency tube heating, noise less than -100db, choke loading, DC powered, auto-biasing, brownout protection, and can even be turned on without any speaker attached without damage(just like a SS amp can), and weighs 5 pounds.
And best of all, it sounds like real music when you use it with a good speaker. It doesn't sound like most tube amps, and it doesn't sound like most SS amps. It sounds like the best of both.
Now, by anybody's numbers, a 1:13 ratio(damping factor 13) of output impedance to speaker impedance is going to be well within 1db(and probably within 0.5db) in frequency response variation over the audio range as long as a nominal 8 ohm speaker is used. Now, if you want to drive Apogee Scintilla's <1 ohm load with it, I'll agree that I cannot do it with this amp effectively. For the speakers that are intended for this amp, it will control them admirably and exhibit a quite flat response, and be musical.
Whew! I'm tired, and had about enough of this.
Regards,
Twl |
Raul, the EA-230 is the older Berning design, which used traditional output transformers. I am referring to the new ZOTL designs which are completely different than the EA-230 was. My amplifier is a ZOTL design.
It is still not "perfect" for all speaker types, but it is a very large step in the right direction for tube amplifiers, when used with the a correctly matched speaker system.
It is my estimation, that this concern of yours which we are discussing, is primarily related to speaker systems which have wide impedance swings into lower impedances that would have negative effects on tube amps with higher output impedances, and on that I agree with you.
However, one parameter does not make an amplifier, and there are speakers for use with these amps which will keep the frequency response/output impedance curves at a level within good acceptable ranges for music listening. While many SS amps do have the very low output impedances that would work well with difficult speakers, that parameter alone does not make them good for musical listening. As you well know, there are other things involved with this.
I am not trying to change the "physics laws". What I am doing is pointing out that a variety of tube amplifiers when used with properly matched speaker systems, can have acceptably flat response curves(even if not perfect), and still provide a very musical result because of other strengths that tube amps have and other weaknesses that SS amps have. I have been primarily on the "defensive" side in this argument, because I don't wish to insult people that use SS amps. But I will say that some of the more expensive and flattest response SS amplifiers that I've heard provided some of the worst listening experiences that I've ever heard. They don't provide specs for "grainy, hard, or cold" sounds. People don't call them "sand amps" for no reason. However, I will admit that some good SS amp designs do provide a very flat response and a tonal quality and overall sound quality that can come close to a good tube amp. Basically, you can "pick your poison", nothing is perfect, and you buy what you like.
What I chose was a carefully selected blend of Single-ended Triode coherence and tone, with similar speed and control of SS(using the ZOTL impedance converter), and the open and transparent sound of OTL. I had David Berning himself design and build it with his own hands. It is the only one of its kind in the world. I selected speakers that would work well with it. It makes music. It is the only item in my system which is not replaceable. I call it "The Holy Grail", because prior to the Berning impedance converter invention, it was simply not possible to have an amplifier with only one output triode per channel in a single-ended triode configuration, with no output transformer, and achieve anywhere near a low enough output impedance to operate any normal speaker. This amp not only achieves a low enough output impedance, but puts it closer to what an SS amp might be(without feedback). In my opinion, this amp is the cutting edge of audiophile amplifier design, going where no amp has ever gone before. Using a single Type 45 output triode to directly drive a speaker element. This is a revolution in amplifier design, because it takes the best aspects of best tube design(SET) and provides a solution for what previously were the drawbacks of the no-longer-necessary output transformers, and provides better impedance matching, and direct drive from the triode. The result is "top to bottom" freqency extension capable of square-wave reproduction anywhere in the audio range, blazing speed, transparency, openness, tone to burn, superb coherence due to the pure Class A design inherent in SET, super short signal path, ultra low-noise due to RF tube heaters and no AC power "grunge" due to rechargeable 12vdc battery power, improved linearity due to choke loading, incredible grain-free liquidity and a musical sound quality overall that is "to die for".
Now if I have to "settle" for a fraction of a db of frequency response variation at a couple of frequencies where my speakers are a bit reactive, in order to get all these benefits, then that's fine with me because I got the better end of the deal. |
TWL out.
Tired of banging head against wall. |
