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Solid State Power: MOSFET vs. Bipolar?

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Posted on October 4, 2010 at 13:26:32
Duster
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I have my own observations/opinions about the notably different sonic signatures of solid state power amplifiers with Bipolar vs. MOSFET transistors. What are yours?

 

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RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 4, 2010 at 16:38:18
TRUFI
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Depends on circuit topology, but this is a cable forum/

 

Oops, posted in CA by mistake (nt), posted on October 4, 2010 at 17:00:40
Duster
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nt

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 4, 2010 at 18:15:33
wirewizard
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I think MOSFET transistors are smoother and warmer sounding than Bipolar transistors. MOSFETS sound more "tube" like and Bipolars sound more "transistor'ish".
I do it all in the name of music!!!

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 4, 2010 at 18:27:04
Duster
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hi wirewizard,

I agree. MOSFET tends to be rather rich sounding vs. the "cooler sounding" more austere bipolar. Both have their sonic merits ;-)

Cheers, Duster

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 4, 2010 at 20:10:16

I have my own observations/opinions about the notably different sonic signatures of solid state power amplifiers with Bipolar vs. MOSFET transistors.

In which instances? You mean where ALL of the transistors are either bipolars or MOSFETs?

se

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 4, 2010 at 20:16:54
hahax@verizon.net
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But I'd rather use neither. I'd use VFETs if they were easily available.

 

Essentially the difference vs. one another (nt), posted on October 4, 2010 at 20:39:42
Duster
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nt

 

RE: Essentially the difference vs. one another (nt), posted on October 4, 2010 at 23:34:11

But do you only mean the difference between an amplifier that uses nothing but bipolars and an amplifier that uses nothing but MOSFETs?

se

 

I'd conjecture he meant output stage nt, posted on October 5, 2010 at 10:57:55
keith_d
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nt

 

Add tubes in there..., posted on October 5, 2010 at 11:02:06
mkuller
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...and it all depends on the design and the designer.

Manley, VTL or ARC for tubes.

John Curl for MOSFETS or VFETS.

Pass, Classe, Ayre and others for bipolar.

These days the good ones sound more alike than different.

Personally I'll take tubes for their harmonic envelope and imaging.

 

Post hoc ergo propter hoc, posted on October 5, 2010 at 11:09:07
Al Sekela
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The details of circuit design, layout, construction, and user setup contribute a lot to the sonic results. Listening to a few samples of each transistor type can be misleading.

 

Yes (nt), posted on October 5, 2010 at 12:04:45
Duster
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nt

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 6, 2010 at 07:38:44
Karma16
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HI,
As others have said, there are many factors that affect the sound. However, I think each of the technologies do have definite signatures independent of other factors.

Solid state Bi Polar: Inexpensive units sound grainy and harsh but they continue to improve. Top end units maybe sound the most neutral, dynamic, and extended than all other technologies. They can sound relentless and place a premium on speaker compatibility. Properly matched, they are my second favorite technology. But at this level of performance they are very expensive. I currently own Krell and Levinson.

MOSFET: They have always sounded a little rolled off in the high frequencies and lack ultimate detail and resolution to me. Other than that, they can be top notch and very easy to listen to. They tend to be forgiving of less than perfect tweeters. I have owned Jeff Roland.

Tubes: Very difficult to characterize. Their signatures are all over the map. What people refer to when they say "tube" sound often means a rolled off high end, weak bass, and a lush, prominent mid-range (the classic tube sound). But, a modern, high end tube amp will not sound this way. Rather, they are neutral, have excellent detail and resolution, great dynamics, and strong bass but not giving up a wonderful midrange. To my ears, a great tube amp is as close to real as can be had. They are my favorites. ARC specifically but also VTL and Conrad Johnson and probably others I have not heard. I currently own, and have for for many years, Audio Research. I really dislike the "classic" tube sound. I am leaving SET amps out of this discussion because I do not consider them to be HI FI.

In summary, I think careful listening will reveal that each technnology has a signature. What a particular listener prefers is strictly personal and depends, to large degree, on their experience with high end equipment and how well the system is matched.

Sparky

 

What he said with an improvement....., posted on October 6, 2010 at 14:48:03
doodlebug
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The details of circuit design, layout, construction, and user setup contribute a lot to the sonic results. Listening to a few samples of each transistor type _will_ be misleading.

Active devices are engineered in to achieve specific design goals. Discussion about one type over another is fodder for discussion at happy hours over beers. You can "admire" the issue but there's no conclusion to be reached.

Cheers,

David

 

Ironically, the best sounding amp that I have heard/built,, posted on October 7, 2010 at 07:25:00
jihad
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has been all bipolar, input, VA, driver with Hitachi Lateral MOSFET outputs.


Go figure.





Never attribute to malice that which can be adequately explained by stupidity.

 

Jfet driving Bipolar, posted on October 7, 2010 at 10:42:12
Jon L
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seems to me to strike about the right balance.

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 8, 2010 at 02:43:48
morricab
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I have found that JFETS and MoSFETS can be nearly invisible sounding in lower current applications (as input and driver stages), especially when used like a triode: single ended, Class A and no negative feedback. Somehow they still don't sound quite as good as a properly done tube amp but much better than bipolar amps.

When used in the typical Class AB, high feedback and complementary designs then I would say that MOSFETS seem to underperform compared to the best bipolar output stages but both sound bad.

The FET is a closer to tube substitute and when used in that way it can sound very good.

 

You just described a Hafler DH-200 from the late '70s [nt], posted on October 8, 2010 at 14:54:16
Charles Hansen
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nt

 

I've never heard one, do they sound that good? , posted on October 8, 2010 at 21:36:10
jihad
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Like I said, ironic.

I've heard jfet/mosfet/bipolar that I thought were outstanding as well.

Speaking generally, I can't say I care for all bipolar, too shrill or all FET, too veiled.


Never attribute to malice that which can be adequately explained by stupidity.

 

Vacuum tube amplifiers as a measuring stick for modern, high current, low feedback SS amplifiers? , posted on October 8, 2010 at 22:31:04
jihad
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I don't think so.

How can you compare the performance you get out of modern, ultra-fast bipolar/FET devices to what you get out of an output transformer, esp. SE? Not to mention the sound?

I like my frequency response flat, not looking like a bell curve, but that's just me.

I realize alot of people like the euphonic 2nd-order harmonic distortion, the reactive nature of the OPT that causes phase shifts and the high output impedance that is another problem.

However, that's not what we're discussing here.

Never attribute to malice that which can be adequately explained by stupidity.

 

RE: I've never heard one, do they sound that good? , posted on October 9, 2010 at 12:12:08
Charles Hansen
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I never heard one either. They were supposed to be pretty good for a $495 kit amp back in 1980. I can't imagine they'd be competitive today, but who knows? What was the amp you liked so much?

 

RE: I've never heard one, do they sound that good? , posted on October 10, 2010 at 05:35:23
jihad
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It's losely based on a Hitachi application note from '77, and then I believe the Maplin 150 shared elements of it. I believe Erno Borbely used elements of this when at Hafler.

An article appeared in Electronics World in August, 2001 that has a modified and updated schematic. I have substituted some parts and use heavily biased vertical MOSFETs.

I am wanting to try lateral MOSFETs as these are supposed to sound even better and would allow me to get rid of the bias circuit and replace it with one fixed resistor.

I'll see if I can dig it up.









Never attribute to malice that which can be adequately explained by stupidity.

 

RE: I've never heard one, do they sound that good? , posted on October 10, 2010 at 08:02:25
Freo-1
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I've never cared for the MOS-FET output amps sound. Every one that I've heard sounded a bit metallic, and there was no doubt that it was MOS-FET.

Now there could some great sounding units out there I have not heard, like Pass Labs current amp line, should sound great.

My preferred amps are Nelson Pass STASIS units, or Yamaha M series. To me, they are the best bang for the buck.

As always, YMMV.
"What this country needs is a good 5 watt amplifier!" (Paul Klipsch)

 

RE: I've never heard one, do they sound that good? , posted on October 10, 2010 at 10:43:36
Charles Hansen
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I still have the original Hitachi databook from 1977 with the suggested schematic, so I know it quite well. The circuit is very ordinary -- nothing unusual at all except for the MOSFETs.

The Hafler DH-200 is fairly similar although with one large difference. The Hitachi circuit is a conventional circuit, with the only complementary stage being the output stage. The Hafler circuit is fully complementary from input to output, as first exemplified by the Ampzilla (James Bongiorno) and later "the Leach amp" (as a construction article in Audio magazine by GIT professor Marshall Leach was popularly known as).

I'm sure that you can find used DH-200's for less than $200, and they would make a fine platform for modification. I think that the XL-280 would be even better, but they are much less common, probably more expensive, and have a JFET input stage that violates your "magic formula".

If you like the vertical MOSFETs, you may or may not like the lateral ones better. The lateral ones are much more linear and even lower in measured distortion. (You may need to parallel additional output devices to compensate for the lower transconductance.) The vertical devices are quite colored (due to their nonlinearities), but some people apparently like that sound. You may or may not be one of them.

 

Whoa, , posted on October 10, 2010 at 13:12:24
jihad
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there is no magic formula. I just mentioned one particular topology I liked.

I'm familar with all those circuits you mentioned. The circuit I'm using has added CCS to the input long tailed pair and a complementary CCS to the VA stage. The bias generator is much better than the one in the Hitachi design. It's simple, basic and has good sound, kinda like Nelson's F5 is simple yet sounds soooo good.


Vertical MOSFETs biased high(er) do much better in practice than their reputation would suggest. I agree laterals sound much better. I had some IRF640 and IRF9640s on hand at the time, what can I say. Next build I'll use some 2sk1058/2SJ162 or equiv.

I like the McCormack DNA-1 Deluxe alot (the real McCormack, not the CJ era stuff). I beleive that's jfet/mosfet/bipolar, so there you go, there is no one solution to everyeone's problem.




Never attribute to malice that which can be adequately explained by stupidity.

 

RE: Vacuum tube amplifiers as a measuring stick for modern, high current, low feedback SS amplifiers? , posted on October 11, 2010 at 10:24:40
morricab
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"How can you compare the performance you get out of modern, ultra-fast bipolar/FET devices to what you get out of an output transformer, esp. SE? Not to mention the sound?"

This depends on what you define as performance. I define it as how the amp sounds not how it measures because, as I am sure you are aware, there is not a good correlation between percevied sound quality and test measurements like THD. It seems that how linearity is achieved has as much or more of an impact than the raw number in terms of % THD.

"I like my frequency response flat, not looking like a bell curve, but that's just me"

As long as your damping factor is more than 5 there will not be a large amplitude swing in the FR curve. The flatness of most speakers will be far worse.

"I realize alot of people like the euphonic 2nd-order harmonic distortion"

Oh this old chestnut. Well seeing as it has been demonstrated that it takes at least 1% of 2nd order distortion to be readily audible I don't think that there is much in the way of "Euphonizing" the sound. The real problem is that we are very sensitive to high order harmonics that are present in high feedback and Class AB designs. These destroy the sound, whereas little old 2nd order is essentially sonically invisible.

The real problem with many tube amps is the output transformer but not at the high frequencies (A good one is quite linear up to 20Khz). The real problem is at low frequencies and core saturation. This is one of the main reasons for "tube" sound. If you have ever heard good OTL amps you will note that they sound distinctly non-tubey in that golden way but also distinctly non-transistory.

"However, that's not what we're discussing here"

What exactly are we discussing then if not perceived sound quality as THE benchmark for amplifier performance. Clearly the numbers, at least on the surface, don't support subjective findings. See papers by Geddes and CHeever and you will see what I mean.

 

RE: Whoa, , posted on October 11, 2010 at 10:28:40
morricab
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BTW, Mosfets don't sound veiled when run in Class A and without feedback. In this respect they are quite tubelike.

 

RE: I've never heard one, do they sound that good? , posted on October 11, 2010 at 10:32:54
morricab
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I recommend that you try a true Class A design (or at least heavily biased A A/B) with little or no feedback. Hybrids in particular work well with a Mosfet output stage with nary a veil or metallic sound in site.

Some examples:
Sphinx Project 16 (100 watt Class A hybrid with Mosfet output)
Sphinx Project 14 (180 watt Class A A/B hybrid (20 watts Class A)with mosfet output)
Monarchy Audio SE160 (160 watt Class A A/B hybrid (50 watts Class A) monos with Mosfet output)
Acoustic Plan Santor (50 watt Class A A/B hybrid (20 watts Class A) with mosfet output)

 

Funny, that's exactly what I heard that I didnt' care for. , posted on October 11, 2010 at 11:17:47
jihad
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There is nothing wrong with negative feedback.

IMO tubes sound veiled, that, among other reasons is why I prefer SS.

I have posted on this.




Never attribute to malice that which can be adequately explained by stupidity.

 

RE: Funny, that's exactly what I heard that I didnt' care for. , posted on October 12, 2010 at 02:51:37
morricab
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"IMO tubes sound veiled, that, among other reasons is why I prefer SS."

You obviously haven't heard good tubes, both with output tranny and without output tranny. The clarity of a good tube design makes all the SS I have heard sound, well, wrong.

Go hear a well designed OTL amp and you will realize that all the amps you have had before were very veiled.

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 12, 2010 at 09:18:55
pictureguy
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Karma,
I'm just curious. If I set up a system, you could tell me what devices / technologies were in the amp? No Peeking!
At what level? 50%? 80%? or more?


Too much is never enough

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 12, 2010 at 12:51:37
antoneb
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I have a bunch of Fets BJTS and MosFets sitting on my desk.
I'm listening really hard, but they don't sound like anything to me.

"To Much is never enough...

...except when its just about right."

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 12, 2010 at 17:16:26
Karma16
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HI,
Probably but much depends on the quality of the system and the amount of exposure. But I would not even try when you have not filled out a profile system. Why should I work for you when you have not worked for me? I want to see what your decisions are when you have to pay.

Of course, all this is hypothetical since this circumstance will never happen.

Check out my profile system. You will see that I have put my money where my mouth is.

Sparky

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 13, 2010 at 16:50:27
pictureguy
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I'll try to fill in a profile system....whatever that is....or do you mean system profile? Although I simply don't see what my system has to do with the question. Nobody asked you to do 'work', the ultimate 4 letter word, maybe.

As for the rest:: I am just thinking about characteristics being ascribed to a part....in this case a transistor...be that bipolar, JFET, MOSFET, Various 'N' or 'P' channel devices....or whatever. The wisdom is that some stuff sounds a certain way. No mention is made of the gain stages in front or in back of the part in question. Or the circuit topology used, which IMO should make a bigger difference.

Also, and this is just my opinion, I'd like to see a comparison of 'best' with 'best' and see who can tell what and how much difference....and If certain parts can easily be identified. Same goes for class of operation....'A' 'A/B' or even 'D'. Just a difference would make me happy. Not a value judgement of best, but just difference.


Too much is never enough

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 13, 2010 at 18:39:24
Karma16
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HI Picture,
Good. Thanks for filling out your system profile. It's helpful to me so I can choose the right terminology with which we can talk. It also gives some idea of your experience and sonic tastes. I find it very helpful and I think others do too since I find forums a difficult medium to communicate complex ideas.

I think you are expecting too much. The finest minds in audio have been fighting with your questions as long as hi fi has existed. I will give you my view about amps and sound. Take it for what it is worth.

I do not believe in mixing technologies. IOW, I belive that a system should be all solid state or all tubes. The entire equipment chain is involved in this monoculture. This becomes more important when great and expensive equipment is under consideration. More than technologies, one must gain an appreciation of the sonic tastes and goals of the equipment desgners. The great ones always develop designs that have their own personal signature sound. At this level one buys the designer rather than the technology.

It is also true that each great designer also has a pet technology. For example, Audio Research is known as a tube company. Krell is known as a bipolar solid state company and Jeff Roland has excelled with FET designs. Each of these companies have a characteristic sound unlike any other. So, can we talk of the technology or the designer? In truth the two go together. We must talk about them together.

In the cases above, each of the companies produce excellent sounding designs but they are all different from one another and different from any other using the same technology. So, if one were to say that Krell is their favorite amp then that same person would also say that bipolar solid state is their favorite technology. The same would hold for me when I say my favorite technology is tubes. What I am really saying is my favorite sound is from Audio Research who happens to use tubes. Thus, by this logic, I prefer tubes.

I have heard many tube amps that I don't like. I have also heard many solid state designs that I would not own. Conversely, I have heard solid state designs that I prefer over most of the tubes I have experience with. The conclusion I have come to is the execution of the design is more important than the technology. I currently own Audio Research (my main system), Krell (my HT system) and Levinson (drives the subwoofers in my main system but used to be the amp I used in my main system). So, as you can see, I am an equal opportunity hi fi fanatic.

But, at the far frontier of hi fi, I choose tubes for my sonic nervana. I think tubes ultimately offers the best potential. At this level of performance, trying to describe the sound is almost beyond what the language is capable of describing. But, my ears know it even if I don't have the words to properly describe the experience. And I'm not going to try here.

My suggestion is to expose yourself to as many amps as you can always using the same demo material. Try to eliminate as many variables as possible. You will develop a sensitivity for certain characteristics of the sound. As your listening skills develop you will hear commonalities. Then you will decide what you like. Discipline yourself to write down what you hear. You need to develop your own sonic vocabulary. Be careful to maintain a balanced outlook and not get caught up with a particular characteristic that you may reject in a few weeks. Remember, we have all made this mistake and this can get expensive.

Study the amplifier topologies and correlate them to what you hear. With time you will hear the answers to your questions. This is the only way. Hi fi is a learing, self-involving experience.

Sparky

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 13, 2010 at 20:56:35
pictureguy
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Well, I don't know how my system profile helped, but there it is. I'm doing the best I can with limited space, though I CAN turn it up as loud as i want.......Also, I am a 'stability' guy. I DO NOT have the resources to change gear on an experimental whim. Even when I was making 6 digits, my system was stable for about 20 years. My Carver Cube was dumped in favor of a Rotel, which lasted about 6 months, the ONLY time I've simply dumped something I didn't like or made such an awful error. I can remember nearly every major piece I've ever owned, including a Pioneer SX727 receiver and a Kenwood integrated. (powered my MG-1s for a short time)

Now, all those amps and companies DO have a house sound no doubt. Just my Opinion, but someone who says they like Krell doesn't say much about Bipolar. Sure Krell is bipolar, but than many others are as well, some of which person 'x' may not like.

Also, what governs the 'sound' you recognize? Most amps feature several gain stages. The possibilities are near-limitless with

2 examples you missed are Mac and Pass. Mac is Mac and has been so for a long time. Like good Champagne it is 'blended' for the Mac sound and exhibits great consistency over long time periods....and I don't even know who to credit for the design though these days I'm reasonably certain they are 'voiced' by committee.

Nelson Pass? Threshold? some Adcom? And, while Pass is typically a MOSFET guy, his amps are frequently current source, not voltage source. His designs are maybe the most varied of any single designer, living or dead.(Including Bob Carver) They run the gamut from his first watt stuff to the current (no pun intended) XA stuff. Panels and Pass seem like a good match, too.

As for mixing SS and Tubes? Wow, what a can of worms. So many philosophies, some from people I've known for a while and respect. I could see myself one day, owning a tube preamp, but am not looking and won't until after I win the lottery. Age-wise, I'm less than a year from Nelson Pass age, and was raised with tubes. And the annual trip to the local tube tester!

And finally, Man, I WISH I could 'test amps in my system' as a paraphrase (I hope) of your suggestion. And also yes, no telling what I'd 'find'. Maybe I like Krell, though my brief experience says NO. Mac and Maggies? I've only seen a few posters with such a match. Me? I'd love to try Bryston and maybe some 100 watt or better tubes on my panels. I suspect from looking at the electrical measures that Magnepan and tube are a good match. Low reactance and reasonably flat impedance. Nice.

Maybe my tagline should be ::

If I was only born rich, instead of just good looking!


Too much is never enough

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 13, 2010 at 21:03:16
pictureguy
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Hey, get your own tag line!
Just kidding.

Aren't you the 'transistor whisperer' we've heard rumors about on the internet?
Too much is never enough

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 13, 2010 at 21:06:50
pictureguy
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It will be interesting to compare Krell with the NEW line from Dan D'Agostino. Especially if he makes major semiconductor or topology changes......Just a thought?


Too much is never enough

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 14, 2010 at 00:04:38
antoneb
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Posts: 57
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Heh heh to quote the all mighty TICK

"More is More, and less is less! More is better...

...but twice as much is also good!"

"Too little is bad and Too much is never enough...
...except when its just about right!"

I sense that your Silicon devices feel jealous after catching you looking at those tubes.

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 14, 2010 at 04:29:52
Karma16
Audiophile

Posts: 1081
Location: White Rock, New Mexico
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HI picture,
There is a way to expose yourself to a variety of amps, in your system, and not cost a fortune. Buy excellent stuff used. The operative word is EXCELLENT. The initial entry price can be high but after that you can turn over equipment at no loss or possibly even make a profit.

This method won't get the most current equipment because to make it work you have to wait until depreciation is maxed out. I have found that great amps remain great for a long time. So, for example, a great ten year old amp will still be very close to the state-of-the-art represented by current models.

I think this is less true of solid state amps than tubes. Solid state amps are still evolving trying to overcome basic problems inherent with the use of bipolar transistors. But they continue to improve. The best of the ten year old solid state designs can be excellent even now.

You are right. I left out Nelson Pass. I wasn't trying to be comprehensive. I was trying to illustrate my point with brands I have owned. I am a big admirer of Nelson Pass. My leaving him out of the discussion should not be taken as a put down or ignoring one of the great modern amp designers. The "buy used" technique should not extend to Threshold (Pass designs). They can't be maintained with reasonable ease. Great amps though.

I note that you have Maggies. I have always liked them no matter the model or age. When I was in the market for a magnetic panel speakers, the choice came down to Maggies and Apogee. Eminent Technology was not on the market yet. Apogee won. But not for long. I ended up with Martin Logan CLS IIA electrostatics which I still love 20 years later. Now here is a speaker that will expose every wart in a system. With CLS IIA's synergy is extremely important; more than usual. They work beautifully with tubes but most tube amps can't handle the brutal load. My ARC D250 Mk II Servo amp puts those problems aside.

Sparky

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 14, 2010 at 06:22:49
Maxamillion
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Location: New Jersey
Joined: May 26, 2006
You know, I felt the same way until I recently made some changes to the low frequency EQ/buffer unit on my Infinity RSIIb speakers. I wanted to get rid of the output coupling caps so I changed the single-ended, class A MOSFET output unity gain buffer to an OPA827 opamp unity gain buffer (opamps of all things!). The extremely low DC offset of the opamp allowed me to remove the output coupling caps - the result was clearer, less congested sound, without introducing any harshness that I could hear. I'm starting to think that a properly implemented opamp (with enough PS decoupling/bypassing) can sound damn good. Perhaps it might be a different story in a gain stage.

The opamp buffer stage is on the tan board in the picture below (just below the board you can see the MOSFETs still in place, I left them in just in case the experiment was a flop).




 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 14, 2010 at 09:07:23
pictureguy
Audiophile

Posts: 3715
Location: SoCal
Joined: October 19, 2008
Yep, karma,
I've been aware and heard of people doing the preowned swap and roll thing for a while. I'm not going to get on that bus.
And yes, there are bunches of amps out there which would qualify as testable. I'd personally like to try a Mac with my panels. Or Bryston....or a Pass.
I have no interest, however, in going 'tube'. Here's what would happen. I buy a nice tube amp. Something of decent power and good reputation. I don't like it. Than the trouble would start. 'Why didn't you try XYX tubes?' OR 'Those nasty I/Cs are the problem.....Junk 'em out!' OR 'You use WHAT for speaker wire? That's in insult to that fine amp'.
I've seen suggestions and comments like above for while now. Even stuff that makes no sense. Guys' got a hum.....Sounds to me like some kind of ground problem or maybe a dimmer or other device on the same line. Next thing you know, he's induced to lift all his grounds, buy a 2kva iso transformer and get the power company to run him a new feed and transformer. Problem persists. His wife sews at the times he likes to listen and the motor control of the sewing machine is putting some 'hash' on the line and some RF in the air.

I see you've had your speakers for a LONG time....at least by hifi standards. This is a good thing, to me, at least. I had my first set of panels for 20+ years and a rebuild thru WhiteBear Lake. Sold 'em to buy some 1.6s and a new amp.... Magnepan is Magnepan...even over longer time periods. The only thing they screwed up, IMO was when they rotated the pole piece to the BACK and sold 'em with the mylar side to the listener. Just my opin, but I have ROTATED my panels and listen to the pole piece side to great satisfaction.

Cheers::
Too much is never enough

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 14, 2010 at 16:58:03
Karma16
Audiophile

Posts: 1081
Location: White Rock, New Mexico
Joined: October 26, 2006
HI,
I can understand, I guess, you not wanting to go to tubes. But, you act like your actions are being driven by others. That I do not understand. If you want to learn, you must do it yourself and to hell with what others think, including me.

Sparky

 

RE: Solid State Power: MOSFET vs. Bipolar?, posted on October 14, 2010 at 19:30:47
pictureguy
Audiophile

Posts: 3715
Location: SoCal
Joined: October 19, 2008
I can see, perhaps where my last post may lead you astray. The couple brands I mentioned include 2 which are mentioned a lot with Magnepan and 1 which isn't...Mac.
Not accurate. I'm a little on the obsessive side so approach things like a lunatic. IF I bought tube gear, I'd be tempted to go the 'rolling route' and finish off my last active brain cell. IF I did buy tubes I'd start with a pre. I understand (correctly?) the tubes last longer. The other thing. If I bought tube stuff, I'd end up with a tube checker and 300$ worth of Fluke and maybe even a scope....than cap tests and the road to insanity.

The fact that I'm not nutty about cables and power cords is evidence I'm not letting others choose my stuff by consensus. I DO see bunches of that, however, and you only rarely see my moniker in one of those 'what do I buy' threads where somebody asks about the 'best' something. I advocate listening. Tour local stores and get ideas of what you do or do not like. stuff like that. I've read many threads, for entertainment value, in which people advocate nearly opposite views...just a couple posts apart. The one 'best of' threads I did answer was one about inexpensive balanced cables. I was about the 5th person to advocate Mogami....while some other people were spending the OP's limit of 300$

Personally, I'd like to go hear more live music. I think that is my big weakness. I'd also like a larger base of stuff I've heard. The local emporiums are good for that and always have something interesting on, and I don't bug 'em......though I occasionally bring some interesting music.
Too much is never enough

 

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