Thread: Possible amp trade advice

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  1. #21
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    Default Re: Possible amp trade advice

    Giraffe,

    Checking - you've experimented some and tried a balanced bias (meaning hotter instead of the Pee-vee standard of frigid) for the 5150?
    Oh, and also, this is the fender one. Is it stilled biased cold?
    I'm a fan of cheese!
  2. #22
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    Default Re: Possible amp trade advice

    Oh, and also, this is the fender one. Is it stilled biased cold?
    Fender has historically had a tendency to bias cold, as it makes the tubes last longer and makes the amp more reliable. I can't say for certain if the current regime still follows that policy or not, however.
    http://www.johnnyoklahoma.com/

    Originally Posted by Bob Ohlsson
    Everything is some mixture of awesome and suck. We simply want the awesome to be highlighted sufficiently that it distracts listeners from the suck.
    Originally Posted by Bob Ohlsson
    The appropriate role for science is the study of observed phenomena to gain an understanding. It is not dictating what people ought or ought not to be observing.
    Hey, if I'm Grumpy, where the hell is Snow White????
  3. #23
    Voice like Marcel Marceau Waiting for his millions from Nigeria
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    Default Re: Possible amp trade advice

    Never tried that particular Framus, but I've not been that impressed with the stuff I have come across - a mate had a 4xel84 ac30-esque model that sounded quite stiff and bland next to my AC30cc (which is hardly one of the better vox models) - then it blew a GZ34. The cab didn't feel that well built either. Kinda struck me as Boutique brand without the associated build quality. And they did the mismatched speaker thing which drives me mental for some reason. A greenback and V30. Just make up your mind!

    Then a few years later I had a front loaded closed back 2x12 and it was the worst cab I've ever heard - way too stiff, directional, no cab resonance, very very shrill.

    I've never had a very good relationship with mesas, for what ever reason...and the only one I ever personally really liked was the lone star...
    I used to be like that, then I got a Stiletto combo just to have a higher gain amp kicking round, and fell in love with it. Never expected that. Especially once I'd changed out the V30s for some 35 year old G12-65s.
  4. #24
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    Default Re: Possible amp trade advice

    I turned him down. Thanks all for your opinions.
    I'm a fan of cheese!
  5. #25
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    Default Re: Possible amp trade advice

    And it continues....
    Someone has offered me a Barron k88.
    It's a pretty small shop, but the stuff looks good. Only problem is there is no name recognition. Which matters sometimes to customers, and of course for resale value.
    http://www.baroncustomamps.com/faq.php
    I'm a fan of cheese!
  6. #26
    Hates these rank titles! Thinks Alfred Einstein was a genius
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    Default Re: Possible amp trade advice

    If its a good boutique style amp from a decent shop then just take the badge off it and let the clients ears decide! Good luck with the hunt - I've only been through a dozen or so amps in 25 years mostly due to lack of budget and still haven't quite found what I'm after. I'm beginning to think more and more that blending two amps might be the way to get the tone I'm chasing!

    But then tone is in the fingers...

    Andy
    shut up and play yer guitar...
  7. #27
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    Default Possible amp trade advice

    Hahaha. Unless it's my fingers.
    Well, I suppose there's a *sort* of tone in my fingers......
    Last edited by giraffe; February 16th, 2016 at 05:18 PM.
    I'm a fan of cheese!
  8. #28
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    Default Re: Possible amp trade advice

    Tone in fingers are sometimes spotted in listener reactions. Look for spontaneous dancing about architecture and facial expressions.
  9. #29
    Surfing the net at work every day! Has proof that JFK was president
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    Default Re: Possible amp trade advice

    Giraffe,

    Eh, sorry for the belated reply.

    I don't know enough (read: next to nil) about power electronics to be able to give you a figure, but a good amp repairman can, having a circuit diagram and a spec sheet of your power tubes, make educated guestimates as to what the bias should be. Your 5150 would (John - correct me if I'm wrong here) have some kind of SLO-100 based circuit, which is relatively simple.

    The reason I mentioned biasing is threefold:

    1. It can drastically influence the tone, note clarity, response and girth of the sound. It really is as close to magic pixie dust as you're ever likely to get for tube amps. If you have the bias reset, it might also be a good idea to ask the repairman to check that all of your preamp tubes are okay. Again, someone more knowledgeable, correct me if i'm wrong, but an old/dodgy phase inverter tube won't do wonders for the tone either.

    2. Your repair dude would also be able to tell you if your power tubes are reasonably well-matched. I can very well imagine someone blowing out a powertube and simply replacing it with any tube of the same spec lying around before selling it.

    3. Finally, when you bias an amp, or have it biased, you tend to appreciate the value in amps that are solid, but simple. I've recently borrowed a friend's single-channel Soldano for a recording session, and had it biased beforehand. I can tell you now that it made one hell of a difference, and that the repairman was appreciative of the Soldano's build. Also, I'd happily trade my friend any Mesa for that single-channel Soldano.
  10. #30
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    Default Re: Possible amp trade advice

    What I loved about the THD Univalve was the ability to auto bias. No matter what tubes you slipped in (it could house most of them) - it always landed on its feet. If I wanted a high gain boutique amp I'd at least try some of the more powerful THDs. Flexi. The ability to hone the tone by changing tubes is brilliant.
  11. #31
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    Default Re: Possible amp trade advice

    Giraffe,

    Eh, sorry for the belated reply.

    I don't know enough (read: next to nil) about power electronics to be able to give you a figure, but a good amp repairman can, having a circuit diagram and a spec sheet of your power tubes, make educated guestimates as to what the bias should be. Your 5150 would (John - correct me if I'm wrong here) have some kind of SLO-100 based circuit, which is relatively simple.

    The reason I mentioned biasing is threefold:

    1. It can drastically influence the tone, note clarity, response and girth of the sound. It really is as close to magic pixie dust as you're ever likely to get for tube amps. If you have the bias reset, it might also be a good idea to ask the repairman to check that all of your preamp tubes are okay. Again, someone more knowledgeable, correct me if i'm wrong, but an old/dodgy phase inverter tube won't do wonders for the tone either.

    2. Your repair dude would also be able to tell you if your power tubes are reasonably well-matched. I can very well imagine someone blowing out a powertube and simply replacing it with any tube of the same spec lying around before selling it.

    3. Finally, when you bias an amp, or have it biased, you tend to appreciate the value in amps that are solid, but simple. I've recently borrowed a friend's single-channel Soldano for a recording session, and had it biased beforehand. I can tell you now that it made one hell of a difference, and that the repairman was appreciative of the Soldano's build. Also, I'd happily trade my friend any Mesa for that single-channel Soldano.
    The importance of tube matching is somewhat overstated these days (it gives tube sellers an excuse to boost the prices on matched sets), the reason being that although the tubes may be perfectly matched when you buy them after a few hours of use they probably aren't really that well matched, anymore. Also, I question your assertion that "your repair dude" should be able to tell you how well they're matched as the vast majority of tube testers can't match tubes, they just check for shorts, gassiness, and whether emissions are present. To match tubes (or test for matching) requires a specific type of tester called a mutual conductance tube tester, which measures the actual gain of the tube. They're around, but tend to be a bit pricey, and the tech needs to be hip to the differences between different types of testers. Again, most tube testers are just shorts and emissions testers, not mutual conductance.

    Back in the old days we NEVER worried about tube matching - that was something nosebleed hi-fi snobs did - and never had any problems. It will make a little difference but not as much as the tube pimps would have you believe and, as I said above, after the tubes burn in for awhile they probably won't really be matched anymore. As long as the tubers aren't grossly different (one really weak and one really strong) I wouldn't worry about it much, or at all. My guess is that if you'd mentioned it to Leo Fender he would have looked at you funny.

    Biasing the amp definitely can change to tone considerably. Generally speaking, the hotter the amp in biased the better it will sound. However, the flipside is that the hotter the amp is biased the shorter the life of your output tubes and if it's biased too hot you can destroy your output tubes and take out the output transformer. There should never be even the slightest hint of a dull red to orange glow on the plates - if there is you're ruining the tubes. The brighter the glow, the faster the tubes will burn and the greater the danger to your transformer. If you ever see your plates (or one plate) starting to glow, turn the amp off and take it to a tech before you incur expensive damage. Biasing the amp is something of a fine art - you have to achieve a balance between what sounds good and what might damage the amp or burn the tubes too quickly. The other thing to be aware of about biasing hot is that it makes the amp more sensitive to power line surges. Biasing hot moves the operation of the amp closer to Class A, which means that each side of the push-0pull is conducting more of the time and the flow of electrons when the tube is in the quiescent state is increased. You don't want too much electron flow in the quiescent state.
  12. #32
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    Default Re: Possible amp trade advice

    What I loved about the THD Univalve was the ability to auto bias. No matter what tubes you slipped in (it could house most of them) - it always landed on its feet. If I wanted a high gain boutique amp I'd at least try some of the more powerful THDs. Flexi. The ability to hone the tone by changing tubes is brilliant.
    Yes, amps that are cathode biased (self biasing) rather than fixed bias never need to have the bias set and indeed CAN'T have the bias adjusted unless you replace the cathode resistors.
    http://www.johnnyoklahoma.com/

    Originally Posted by Bob Ohlsson
    Everything is some mixture of awesome and suck. We simply want the awesome to be highlighted sufficiently that it distracts listeners from the suck.
    Originally Posted by Bob Ohlsson
    The appropriate role for science is the study of observed phenomena to gain an understanding. It is not dictating what people ought or ought not to be observing.
    Hey, if I'm Grumpy, where the hell is Snow White????
  13. #33
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    Default Re: Possible amp trade advice

    Is that related to different amps with the same output tubes having different output?

    For example:

    Fender Bassman 50, 2 x 6L6, 50 watts RMS.

    Supro 1696TN, 2 x 6L6, 24 watts RMS.
    Man! You have GOT to try a hit of this RANGE SUNSHINE!

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  14. #34
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    Default Re: Possible amp trade advice

    Is that related to different amps with the same output tubes having different output?

    For example:

    Fender Bassman 50, 2 x 6L6, 50 watts RMS.

    Supro 1696TN, 2 x 6L6, 24 watts RMS.
    It enters into it some, yes - cathode bias amps usually have somewhat lower output. But there are other factors. If the amp is biased to run in Class A (regardless of whether it's fixed or cathode bias) it will put out a lot less audio (and a lot more waste heat) than if it were in Class AB. Possibly the biggest factor, in any class. is the plate voltage - the higher the voltage, the higher the power. However class is of more of less equal importance to plate voltage.

    However class and plate voltage kinda go together, as Class A won't support as high a voltage as Class AB.

    Output transformer design enters into it as well. An Ultralinear transformer (used in newer '70s Silverface amps like the 140 watt Twin) with addition taps in the primary for the screen grids will put out more power (and support a bit higher plate voltage) that a regular design without the extra taps.

    An additional factor that enters into it is the type of circuit used for the output tubes. If they're wired as triodes then output power will be low. If they're wired as pentodes (taking advantage of the extra grid elements in the beam pentode tube) power will be significantly higher. (The Ultralinear transformer uses the tubes in pentode mode, but that's not the only way to do it. Older, nonUL Fenders from the late 50s on generally run the tubes as pentodes, but with the screen grids running off resistors simply connected to a tap in the power supply a few volts lower than plate.
    http://www.johnnyoklahoma.com/

    Originally Posted by Bob Ohlsson
    Everything is some mixture of awesome and suck. We simply want the awesome to be highlighted sufficiently that it distracts listeners from the suck.
    Originally Posted by Bob Ohlsson
    The appropriate role for science is the study of observed phenomena to gain an understanding. It is not dictating what people ought or ought not to be observing.
    Hey, if I'm Grumpy, where the hell is Snow White????

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