You're asking the right questions. I haven't read his books but i've seen enough quotes from them and read enough on his website to know that he and i don't see eye to eye on too many subjects.
I will say that to achieve ultra-wide bandwidth with excellent linearity typically entials fast response out of the circuitry. The faster the circuitry, the less likely you are to suffer from ringing and / or under / overshoot. Combining this with the proper impedances lends stability to the circuit. When you've got speed and stability, you've got good performance that is consistent without the need for a lot of error correction. The more error correction that you have has to do with the lack of speed or consistency in processing the signal. Rather than make the circuit slower and more complex, why not just design the circuit right in the first place? Wouldn't that be better than trying to band-aid it after the fact???
As a side note, i've never read but have also heard good things about Randy Sloan ( or Sloane's ) books. Anyone familiar with those and if so, how do they compare to Self's books? Sean
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I think that what Audioengr was getting at is that there are loop-holes to every generalization. That is, something can deliver flat response over a wide bandwidth at a given amplitude on a steady-state basis, but that doesn't mean that it will respond correctly to changes in amplitude in a linear manner. While i agree with that, it all boils down to speed and impedances. If you've got the speed, the circuitry can respond as fast or slow as needed. If the impedances are right, power transfer is maximized and dynamic variations in amplitude don't present a problem. It really is simple if you think about it and that's why i can't understand why most of the products on the market are the way that they are i.e. under-designed and over-priced.
All of this stuff was talked about and dealt with 30 years ago by a designer that never got the credit he deserved. That person's name is David Spiegel. Too bad he only ever marketed one product as i'm sure that he would be an "audio legend" had he kept at it. His ideas were light-years ahead of most, yet he was humble enough to admit that his ideas weren't original at all when i spoke to him about them. Sean
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Hammy & Marakanetz: I'm somewhere between the two of you. That is, i believe that you CAN hear specs, if the tests are performed in the proper manner and ALL the spec's are taken into consideration and properly interpreted. Having said that, Pro gear typically won't give you the spec's that you need, so they too are about as useless as the lack of spec's that most "hi-end" manufacturers offer. Sean
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Hammy: That's why i said ALL the spec's have to be kept in perspective and properly obtained, not just "some of the spec's have to be good" or "some of the spec's were obtained in a manner that isn't representative of real world conditions", etc...
El: Nice explanation.
Andy2: Some of the things that you say aren't available from spec's are "kinda sorta" interpretable via spec's. I agree about soundstage width and depth though. Sean
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Andy: How's this for a list? Slew Rate, Rise & Fall Time, Rated Power Bandwidth, Rated Frequency response, Current Capacity ( steady state and peak ), Output Impedance, Square Wave Tilt @ 20 Hz, Power Output @ clipping into various impedances, THD, IMD, S/N Ratio, Quantity of Global Feedback used, Phase Response, Time Delay, etc...
Like i've said before, if one has access to a wide variety of spec's and those spec's were derived using proper testing procedures, one can have a good idea of what to expect from an amp and / or how consistent it will be with different loads. Some amps are sonic chameleons because they don't achieve a high level of electronic stability and this will be reflected in the various spec's / test results. If one familiarizes themselves with the proper interpretation of these spec's, they can get by with just a portion of the above information and make a relatively well educated "guesstimate" in terms of sonic performance. Sean
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PS... Since some spec's are influenced by others, it's possible that a manufacturer could leave out specific spec's that would explain why others would look so good on paper, yet sound so bad in real life. That's why more info is always a good thing as it gives you more of an explanation as to what is going on in the grander scheme of things. |
Hammy: Bob Carver's older design's wouldn't pass the spec test and that's why they don't pass the sonic test either. If you think that they did / would pass the spec test, then you're not interpreting the spec's right.
Having said that, you can believe / interpret things the way that you want, but i've already proven to more than a few here that my interpretation of sonics based on measured performance is pretty close. After all, some of these folks have emailed me with nothing but spec's, yet i was able to describe to them what they were hearing, why and how to at least partially correct it. I've also made similar statements publicly about a couple of different amps, their sonic traits and their lack of ability to integrate into various systems. Others that own / have owned those amps supported those comments. The comments that i made were based on interpretation of technical data derived from test results. I'm not saying that everyone can do this, but obviously, some folks can do it better than others. Sean
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El: Thanks for summing that one up in fewer words than i would have : )
Marakanetz: I was referring to "older" Bob Carver designs i.e. Phase Linear, Carver Corporation, etc..., not his current Sunfire offerings. Having said that, even some of the spec's on the Sunfire aren't all that fabulous and it can be heard in the sonics too. That is, the lack of bandwidth results in a lack of high frequency air, clarity and detail as compared to the finest of amps. While the Sunfire's are no slouches, i don't consider them to be "show-stoppers" either. They do offer very solid bang for the buck though, especially where GOBS of power are required and thermal losses are a concern. Sean
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PS... A nice sounding and "somewhat reasonably priced" combo that i stumbled into by accident was a Marsh preamp running into a Sunfire amp. It was one of those combo's where each piece on it's own is a very reasonable performer, yet something "magical" happens when you put them together. Can't remember what i had for interconnects and power cords though, so i won't be much help in trying to "re-create the magic" if someone else were to try a similar set-up. |
Newbee: It was the original SS model i.e. the non-balanced version. Given that i'm using my Sunfire's in my HT system, and the Marsh doesn't have a processor loop, it would have been a pain to try and make it work there. I tried the Marsh with other amp / speaker combo's and i didn't really like it. In that specific system though, it sounded very, very good. That's why i had originally called up Marsh and asked about the availability of their Pre-Pro. Since this was probably about two years ago, they were advertising such a unit, but it wasn't available for a LONG period of time after that. As such, i purchased another Pre-Pro but can't find any reliable sources pertaining to the sonics / performance of the Marsh unit.
Tedbu: That's a good observation. Glad you shared it with us. If the feedback circuit itself isn't fast enough or cover a wide enough bandwidth, there's no doubt that it will hinder performance. While this should be a matter of common sense design, i bet that a lot of engineers / designers overlook this factor. Sean
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