Dirk_Hendrik wrote:
You mean this cathode follower actually change the response? I though it was a unity gain gevice, with quite low distorsion of the sound... So it's not a driver at all? I don't see the way it changes the response...
Yep. You're right that is is a no gain device. However, it's still a starved plate design which is, because of the low voltage, totally not interested in amplifying the signal. At nominal voltages it would do a 1* amplification. In this case it will do far less and will therefore round off the hard clipped signal in a similar manner a real tube amplifying stage does at normal voltages when having a decent input signal. When bypassing the tube the tonebone will still work but with far harder clipping.
And this is essential to all starved plate designs. The tube will work but at the, from a higher-fi perspective, at the bottom of its curve. Meaning; distortion. And that was just what we're after.
btw,
If I remember correct, the BK butler patent limits/covers all up to an 80 volts anode voltage. The newer Ibanez Tubeking works at 82 volts. And still ads diode clipping as well since all mayhem it does cannot be done with a single dual-triode.
I don't think they sound overly " tubey " but like a decent overdrive
curious that their new x ? series don't use tubes and also sound decent
Agreed that the bones are overpriced , got the plexi off ebay for that
midbump sound and i'll keep it [ loop in od 2 is a nice touch ]
Some marshalls including the jubilee's have clipping diodes and
also sound decent . The average SS overdrive like the screamers
have a " dry mid range " feel that has it's place and a certain cut to it
into a ss amp , maybe too much [ for me ] blend it with a tube amp
it's another texture you couldn't get otherwise .
Power of suggestion ? can't say you got a tube if you don't have a tube
But nothings sounds like my Marshall except a Marshall and the best way
to get that sound is to have one [ maybe not most convenient , and
not all their amps are great ]
But if a tree falls in a forest ...................
I had a e-mail discussion with Canadian tube guru Kevin O´Connor from londonpower over this. He states that starved plate designs have been around for ages for stuff like car radios, but they don´t necessarily sound what a musician would call "tubey".
On the other hand, his designs frequently use (like said Marshall amp) diodes with resistive compliance that very closely emulate the response of a tube diode. He calls that "diode bounding" and explains it in his excellent series of books.
Interestingly, not many devices do make use of resistive compliance, the King of Tone (and incidentally the Marshall Blues Breaker) is one of them, which probably accounts for their unusually tubey reputation.
aquataur wrote:starved plate designs have been around for ages for stuff like car radios, but they don´t necessarily sound what a musician would call "tubey".
Having said that, it is possible to get a decent tubey sound from starved-plate designs, but most attempts fail, due a general misunderstanding of the peculiarities of valves under such conditions. Importantly, device-to-device variation and reverse grid current becomes significant, so to get the best out you need low-impedance drive to the grid, and a liberal sprinkling of SS buffers to force the tube to jump through the hoops you want, regardless of component variation. The Butler Tubedriver is the only pedal I know of that pulled a few clever tricks in this regard, but sadly no one else seems to have gone down this route.
I have written an article on exactly this subject for Audio Xpress, which will hopefully be published in coming months.
merlinb wrote:The Butler Tubedriver is the only pedal I know of that pulled a few clever tricks in this regard, but sadly no one else seems to have gone down this route.
I'd like to know more about this "resistive compliance"
can you fill us in a little more?
thanks
aquataur wrote:I had a e-mail discussion with Canadian tube guru Kevin O´Connor from londonpower over this. He states that starved plate designs have been around for ages for stuff like car radios, but they don´t necessarily sound what a musician would call "tubey".
On the other hand, his designs frequently use (like said Marshall amp) diodes with resistive compliance that very closely emulate the response of a tube diode. He calls that "diode bounding" and explains it in his excellent series of books.
Interestingly, not many devices do make use of resistive compliance, the King of Tone (and incidentally the Marshall Blues Breaker) is one of them, which probably accounts for their unusually tubey reputation.
HydrozeenElectronics wrote:I'd like to know more about this "resistive compliance" can you fill us in a little more?
O'Connor enjoys giving fancy names to simple things. By 'resistive compliance' he just means putting a resistor in series with the diode/s, so that the signal is not clipped so abruptly.
I could never understand how some guys can make those JMP-1 units sound great, others not so much.
Best I've heard (that I know of) is when Janick Gers (Iron Maiden) uses one, but it's more of an Old School metal tone. And his has been modded - I'd like to know how!
HydrozeenElectronics wrote:I'd like to know more about this "resistive compliance" can you fill us in a little more?
O'Connor enjoys giving fancy names to simple things. By 'resistive compliance' he just means putting a resistor in series with the diode/s, so that the signal is not clipped so abruptly.
I could never understand how some guys can make those JMP-1 units sound great, others not so much.
Best I've heard (that I know of) is when Janick Gers (Iron Maiden) uses one, but it's more of an Old School metal tone. And his has been modded - I'd like to know how!
I have a JMP-1, and have gigged extensively with it. It certainly sounds like a Marshall, and actually sounds rather nice if you don't listen too closely. The only successful mods I was able to make was to swap tubes, and work with the grounding to lower the noise floor (which was initially considerable). I eventually gave up modding and just used it as it was. One sure way to make it sound better though is to use it with a tube power amp.
The great majority of the distortion in the JMP-1 comes from the bridge rectifier circuit (BR3/D12). The tubes only shape the tone a bit. The bridge has another function; it limits the signal into the input of IC12A. If some enterprising experimenter pulls the bridge rectifier, the 4053 input is slammed with way over it's absolute maximum input voltage. Can you say latchup?!?
. 