Tubes Versus Transistors

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by ekp, Sep 15, 2003.


  1. ekp

    ekp Member

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    In the development of Pritchard amps, I ran into a variety of less than accurate information starting with a lot of "common knowledge" concerning tubes versus transistors and continuing on and on. The errors in this knowledge leads to inaccurate prejudgements that have become quite evident. The question of tube versus transistors must also include the circuitry surrounding these devices perhaps even more than the devices themselves. There is a rather long discussion of the more important issues at the following link:
    http://www.pritchardamps.com/pritchardamps/tech_talk/audio_myths.htm

    Eric
     
  2. trisonic

    trisonic Member

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    Eric, Welcome to this place.

    You'll have a hard job persuading people here to throw away all their valve amps! Good luck anyway.
    Why don't you put some clips up?

    Pete.
     
  3. ekp

    ekp Member

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    Well, Pete, we are going to. However, to do a great job appeared to be a real problem until I came up with an organizational approach that required some special electronics. As a result my player will be able to have an overal 50:1 expansion of his efforts and we will be able to put up a huge library of clips that will allow you to select from 4 groups and hear a particular clip of select from 3 groups and hear clips that range through the 4th group so that you can compare this to that and hopefully with the same licks....

    It is not quite clear when all of this will happen. It is the next major bit of work that we will be doing. Fortunately, we have the electronics done. So it is details of the recording that need to be set now.

    Of course I will be doing shows too: Jacksonville this weekend, Arlington next month, and Philly in November. Also I am bringing a headphone amp and headphones so that you can check out the amp through its equilized direct.

    Have a great day, Eric
     
  4. jzucker

    jzucker Supporting Member

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    No offense Eric but I'd rather hear the differences. As an engineer for a major corporation, I've read tons of EE times articles about the vacuum tubes being obsolete. I've embraced modeling and transistor based technologies with open arms and have owned some of each. I still play through a Peavey Transtube Bandit which is entirely transistor based. Yet, my two old fender amps just have a tone that I can't come close to with any modeling or transistor based technology. Frankly, I doubt it's possible with standard transistor based products. I think the only real possibility is through modeling technologies but I believe we are still years away.
     
  5. ekp

    ekp Member

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    The creation of great artistry in solid state circuits is not years away, it is here in Pritchard amps - check out www.pritchardamps.com

    I do not use standard transistor circuits - so you are quite right about that point - however, the point is that you can not just point to transistors or tubes otherwise there would not be a bad tube amp.... On the other hand, transistors do need a lot of help and the circuits that I use are hardly standard and are highly patented.

    You can check out the amps as shows: Jacksonville this weekend, Arlington next month, and Philly in November. Or you can visit Berkeley Springs, WV

    Have a great day, Eric
     
  6. jzucker

    jzucker Supporting Member

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    Well Eric,

    I'll be happy to try the amps. In the meantime, put some clips up because we've heard this before from Peavey, Line6, Yamaha, Johnson, Fender, Pierc, etc.

    They've all attempted in one way or another to create tube sounds with SS (and digital) technology. They've all failed in my opinion. If you have succeded this is great news. Believe me, I have no particular affection for tubes other than their tone. If you can re-create a BF Fender Reverb amp using SS technology and make it affordable, serviceable and reliable I will be quick to jump on the bandwagon but I've been playing and teaching for 30 years and have heard it all.

    Get the clips online and then we'll talk!:D
     
  7. VaughnC

    VaughnC Supporting Member

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    ....after trying one of Eric's 4X10 amps, I am very impressed with the tube tone he's achieved with solid state electronics. Once dialed in, in a blind test with my Super Reverb, there wasen't much difference in the tone and feel of the amps. However, while I personally couldn't mesh with the mechanics of the amp (another thread), when you compare the price of a new Super Reverb reissue amp at roughly $1100 to the Pritchard 4X10 at roughly $2100, that would probably the main issue at this point in time. While Eric's amp has several advantages over comparable tube amps, I have a feeling that the average guitar amp buyer would be hard pressed to spend more money for a solid state amp that sounds at least as good as his favorite tube amp, despite said advantages. For this reason, I think Eric has an uphill battle ahead of him....but, IMHO, he's definitly on the right track with the sound of his amps.

    Also, I honestly think that the cosmetics of the Pritchard amps could be improved upon. Obviously, looks have nothing to do with tone, but a cool looking amp will always get your attention first.
     
  8. ekp

    ekp Member

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    Well, there are a couple of reasons for having heard all of this before. The first of course is marketing and price pressures. You know oats don't cost as much if they have been through the horse already. People only want to pay X for an amp, and the manufacturers make amps for X even if they use some of those predigested oats. When an amp is an amp is an amp and price is your only factor, then you are likely to run into those oats instead of the fresh ones.

    The second is a bit more complex. Electronic engineering has suffered from being born during the reign of the Behaviorist philosophy, which claimed that only things that can be measured are scientific and things that can not be measured must be ignored. Hence, musician impressions of electronics are, you got it right, ignored. Second, electronics is a mathematical nightmare, so to get things done components are simplified - over simplified. In fact, both tubes and transistors are linearized and consequently in this simplified form look equivalent. Taking the linearization notion further, very little work is done on linear circuits driven into clipping and saturation. Substantially larger biasing effort needed in solid state screws up the overdriven response. And finally there are somethings transistors don't do naturally and extra circuitry is needed to get there from here.

    When you look at the discussion on the Pritchard Amps site, compare what is common knowledge with Hamm's paper. First, the notion that tubes produce even harmonics and transistors produce odd harmonics is fundamentally false. In fact, Hamm says that tubes produce both. And then, the transistor harmonic production is not determinable because all of the transistor amps use push-pull output stages (which tend to cancel even harmonics just like tube push pull stages).

    It is important to note that Pritchard amps incorporate a variety of special, patented circuitry to get them to great tone: triode plate characteristics, compression, fat, and expansivie harmonics to name a few. Then add such useful features and the Watts Knob and the Practice Jack and you have got something to consider. Please note the Pritchard amps are the subject of more patents than any amplifier ever built and these patents range from emulation/exaggeration of individual tubes to the structure of the speaker enclosure and appearance features.

    And sound clips are coming.....In the meantime there are guitar shows - Jacksonville this weekend; Arlington next month, and Philly in November. Come on and check them out....

    Sincerely, Eric
     
  9. jzucker

    jzucker Supporting Member

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    Re: Guitar shows. How about Columbus in January?

    Don't make me wait 'til then for clips. Assuming you have a module which emulates a given tube, can you the replicate the sound of any tube circuit which uses those tubes?

    For example, some folks have produced SS amps which have a very satisfying overdriven tone, rich in harmonics and rip with feedback. The harder thing in my opinion is in getting a very dynamic clean tone ala a good BF Fender amp.

    Do you have a module which can "hang" with a Super Reverb for clean tone?

    I still want clips. I don't understand why that is such a big deal...
     
  10. ekp

    ekp Member

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    Pritchard Amps offer several advantages: the versatility of the voice switch to give your amp many different personalities; the Watts Knob so that you can play in smaller rooms without loosing the sag and compression that you appreciate in vintage amps; the Practice Jack that lets you practice at conversational levels and hence maintain domestic tranquility; channel switching and gain boost to give you more looks in an instant; plus lighter weight to get you around easier.

    I do appreciate the fact that Vaughn found a bug in the Sword that he bought, but that has not only been fixed, but verified as fixed by a subsequent purchaser. In addition, we are offering a no-cost option to go beyond the vintage volume relationship between clean, edge, and dirty to provide more headroom for clean. Having that a switched option in on the "drawing board".

    The comparison of the Sword 4-10 to a Super is like comparing a champion dressage horse to a one-trick pony...

    Sincerely, Eric
     
  11. jzucker

    jzucker Supporting Member

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    It's statements like that with no audio clips to back it up which leave me doubting.
     
  12. ekp

    ekp Member

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    Well, you don't have to take my word for it. In these forums there are posts by Carey Cox and CarltonH who are also quite impressed. There are also reviews in Harmony Central. But nonetheless your point is well taken and getting to a recording studio is next on the list. However, listening is only part of the issue. As you know there is the matter of feel and that can make all of the difference in the world.

    Again, there are the shows in Jacksonville, Arlington, and Philly plus if you would like to visit Wild Wonderful West Virginia, you can check them out and give the deer a concert. We are about 100 miles west of Baltimore, MD

    Have a great day, Eric
     
  13. jzucker

    jzucker Supporting Member

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    Where are you located, exactly? I have family in Washington DC and my wife has relatives in W. Virginia. You're exactly right about the feel. Sorry to be so harsh but I'd really like to hear your amps and if they're all you describe them to be, I'd gladly drop vacuum tubes!:)
     
  14. ekp

    ekp Member

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    Since your location is Cleveland, and you have family in DC, then you probably know about I 70 and maybe I 68. At the junction of those two interstates, which is in Maryland, there is a third road, US 522. I am about 15 miles south of that junction (exit 1 in Maryland) and about 3 miles east off of US 522. If you would like to drop in, please contact me, I will give you better directions, and we can make an appointment. This way you can check them all out without being rushed.

    You don't have to appologize. The industry has been feeding musicians a bunch of bull for decades and electronic types have ignored musicians for three score and more. I had to re-examine my engineering training and experience with the logical rigor that I learned as a mathematics major. Beyond the basics, there is a lot of opinion and scarce rigor. Furthermore, you guys pay good money on their word and become disappointed. I knew a player who bought a large manufacturer's solid state wonder, took it to a gig, played it for half a tune, and took it back the next day.

    It was amazing to me to read of an industry marketing executive complain that there is a whole generation of players out there who are not offended by the solid state tone. Not only do these folks have the ear of the media, they have far more resources than I do, and they did not make it happen. (I guess I did get sidetracked there a bit)

    Anyway, I hope that you do drop in. Berkeley Springs is a nice place. See you later, Eric
     
  15. rlinkt

    rlinkt Member

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    Just out of curiosity, is this discussion verging on spam, or total spam, or clean?

    Moderators, please feel free to delete my comment if it is inappropriate.
     
  16. ekp

    ekp Member

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    I may well do Columbus in January - I don't know yet.

    There are two objectives in clips. The first is easy - just give you a taste of what is possible. The second is to give you the whole picture. I am aiming at the second.

    Actually, the tube emulation bit is not quite as you assume. I do have a triode style emulation in the preamps and they are easy to see. However, the output stage is a bit more obtuse. One of my worries is that the common practice is to use phone jacks for connecting speakers. This is an accident waiting to happen. So, I use an output chip that includes a variety of circuit protections: over temperature, over voltage, and over current. Then factor in the Watts Knob, compression, sag, fat and you have something that does not look like a phase splitter, two tubes and an output transformer. However, it does work great.

    Oh, I disagree with you slightly. The really hard tone to get is the one between clean and dirty. That is where the amp wannabees die and die hard. They do not transition from their squeeky clean to their beyond dirty. These amps are designed to distort slowly, be responsive to picking strength, etc. I believe that this region is the magic land for amps where picking strength is traded in for harmonic impressions. You'll love it.

    Rather than modules, I have voice switch selections. Nine of them now that appear 6 at a time on different voice switches. Sword gives you all nine with its two voice switches. The F voice will do what you want and they are in both channels. Then in addition you get the following

    A - Artistic Airy - a cool clean tone inspired by acoustic guitars
    S - Smooth Solo - a bass and treble accent for solo guitar work
    M - Moderately bright - a British inspiration
    V - Very bright - another British inspiration
    L - Liquid Lead - a combination of American & British tones
    H - Heavy dirt - M on steriods
    B - Bass Boost - a mellow jazz tone
    P - Precision Punch - a bass inspired tone that is also useful for guitar.

    These voices cover the gamut from a real nice, but not sterile, clean to a variety of distortion tones via some classic inspirations.

    Have a great day, Eric
     
  17. jzucker

    jzucker Supporting Member

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    That's classically the case but my Peavey Bandit gets a respectable slightly dirty sound. I can plug a Les Paul into the clean channel (no master volume) and crank the amp up and it gets a very respectable early Clapton,slightly distorted tone. I suspect that live through a good 4x12 cab, most folks would be hard pressed to know it wasn't tube.

    Where ALL the SS amps fall short is in emulating the classic fender or marshall clean tone. There is something very unique about a Marshall super lead or BF Super Reverb clean tone that is very seductive and nothing I've heard comes close. The modeling amps' attempts are laughable in my opinion. Equally important is how the amp reacts to the guitar's signal level and impedance, whether it's being pushed by pedals, a hot humbucker, yada-yada. This is where the Bandit excels and the modeling amps fall flat. However, the bandit's shortcoming is that it doesn't quite have the glassyness of a good tube clean amp.

    Here's some constructive criticism for you Eric... You have come onto this board with some very strong words and claims and your website is amazingly void of anything other than techno-speak which is what you are railing about regarding the rest of the industry. No pictures, no clips, no nothing. My advise to you is get your website together before making these claims and postings, lest folks write you off before you've had a chance to show us what you can do. I fail to see why some simple clips done with a single mic and a soundcard wouldn't illustrate the points you are so fervishly trying to get across?

    A clip is worth 1000 words.

    Jaz
     
  18. ekp

    ekp Member

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    I don't believe that a response to a criticism is spam because if there is no response then it becomes the defacto truth. Admittedly that the discussion has moved away from the initial post that was intended to point out that the various views of transistors verses tubes are over simplified and correct only in the context of certain circuitry which is not disclosed.

    I brought this up for three reasons: First, because it took a substantial effort to seperate the good knowledge from the unsubstantiated and wrong opinion. Second, because I get asked questions based upon these erroneous criteria. Third, my research has centered on what musician's want and that notion seems to be quite foreign to electronics.

    Eric
     
  19. ekp

    ekp Member

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    The clips are coming...

    I would like to point out that doing clips is like taking pictures. You can take snap shots or you can take your time, get the lighting right, and take a great shot.

    Phil did a CD with one of my prototyes at a small studio and you can hear the difference.

    Incidentally, Phil is a player with great ears and the point was not to get better than a Bandit, but better than his Super....
     
  20. ekp

    ekp Member

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    The Pritchard Amps web site uses Macro Media Flash to present a series of images in the center of the home page. These images are both very accurate creations from the CAD drawings and photos that show how the CAD images fit together.

    When my computer did not have the right stuff these did not show up on my machine either.
     

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