Wait a minute... 'tis a good thing this isn't a "teenage" forum IMHO. I mean, if it was, we'd be discussing the latest subwoofer for our "boom" cars, (or Wally-world o' Warcraft) rather than tweaking tube circuits!
As for the photoshop picture: give it time! 😀
(You see? Nightanole strikes even as I post. Good man!)
As for the photoshop picture: give it time! 😀
(You see? Nightanole strikes even as I post. Good man!)
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Well i guess if you MELT tubes, you look a little diff...
Scotty "Captain, the dilithium crystals are overheating."
Kirk "Get me some BIGGER crystals"
Scotty "Captain, I'm giving you the biggest ones that will fit in the warp drive."
Kirk "Sulu, warp factor 10!"
Scotty "Captain, the dilithium crystals are overheating."
Kirk "Get me some BIGGER crystals"
Scotty "Captain, I'm giving you the biggest ones that will fit in the warp drive."
Kirk "Sulu, warp factor 10!"
Attachments
What model/year is that Les Paul? Looks like a good one. As far as I know, I've never seen one of THOSE on ANY Star Trek episode.
I didn't show all of the Les Paul's headstock for a reason. It has the word EPIPHONE on it! I have always used rather cheap guitars. I don't play so well any more, so I can't justify spending much money on a guitar. However my wife bought me this guitar for a birthday present about 12 or 13 years ago. It cost almost $600! My daughter still lived at home and she was the drum captain in the high school marching band. There were always band kids over at our house armed with musical weapons. She got me the Les Paul so I could jam with them. Everyone had a Strat including me, so I had to be different. Of course mine was the cheapest, a Mexican Squire I got at Sam Ash for $99.
The Les Paul is the best guitar that I have, and the only one that I haven't taken apart and modded. I have an old Guild "Ultraflex" amp from the 60's that makes a real sweet blues sound with the Les Paul. Very unique amp, one preamp, two power amps each feeding its own speaker. One is an 8 inch, and the other a 12 or 15 (don't remember). The Ultraflex knob sets the blend between the two power amps. I haven't played it in a few years since I don't have room for it right now.
The Les Paul is the best guitar that I have, and the only one that I haven't taken apart and modded. I have an old Guild "Ultraflex" amp from the 60's that makes a real sweet blues sound with the Les Paul. Very unique amp, one preamp, two power amps each feeding its own speaker. One is an 8 inch, and the other a 12 or 15 (don't remember). The Ultraflex knob sets the blend between the two power amps. I haven't played it in a few years since I don't have room for it right now.
awsome George, i am eager to find out the results for those 4D32's.....i believe these babies are better than kt-120's...
YOU were the one that convinced me. Of course the 10% off coupon that Ebay sent me had one day left before it expired, so I got 6 of them. 2 were gassy (the ones in the picture). The seller sent 2 new tubes. One lights up purple. I have already tested them in a SSE.
I will see what they do in the red board soon, but I have heard that they like AB2, so they will be tested again later with a mosfet driver board.
Equal time will be given to little tubes too, and even some DHP's (307A / VT225)
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Not to hijack the thread too bad...nothing wrong at all with an Epiphone Les Paul unless it's like the gold top I had in '73, it was the feedback king and I never fixed it. Now I play a 1998 G&L Legacy, and a blond 1980 something G30 Guild acoustic.
thanks George, the 3% distortion figure quoted for classAB2 is simply too hard to ignore....
i am using a voltage doubler plate supply so that i can easily provide lower voltages for the screens...
i am waiting on how hard you can push these tubes.....i think with the largish plates, more power can be attained.....i await with bated breath....😀😀
The plate size determines how much power the tube can dissipate. The cathode size determines the peak emission capability, which determines how load the load impedance can go before distortion, or worse happens. The maximum plate voltage determines how high the load impedance can go before possible sparks happen. The dissipation and the efficiency of the amp determine max power if everything is working right.
The cathode size in the 4D32 is smaller than the big sweep tubes that I have been using and the maximum plate voltage spec is 600 volts, so the 125 WPC number might be a real limitation if the specs are real. I will find out how far things can be bent, within reason. Even with the discount, these were $20 tubes. I have some $4 sweep tubes that can do 200+ WPC ,so......
The Raytheon data sheet shown at Franks shows 600 V max. Either way my 1KW HP adjustable power supply goes to 650 volts max and I will go there.
http://www.mif.pg.gda.pl/homepages/frank/sheets/138/4/4D22.pdf
http://www.mif.pg.gda.pl/homepages/frank/sheets/138/4/4D22.pdf
^ i got mine from Surpluss Sales of Nebraska for about the same price...they were running a special price discount at the time, i bought 8 of them as i had 3 that i got from my local source for a tad higher price....
^was looking at the specs again trying to find that 3% distortion spec, turned out i got cockeyed again...
i did notice that there is a limit of 25k for grid leak resistor, so cathode followers or source followers are a must.....
i did notice that there is a limit of 25k for grid leak resistor, so cathode followers or source followers are a must.....
Hello to everyone...
I am currently collecting material to complete the enginner's amp according to the specs available on the peter millet website.
Unfortunately the IXYS current regulator is unavailable in Italy (no chance whatsoever of finding it 🙁 ).
There is however the Supertex DN2540 which supposedly is a good substitute.
Could somone please help me finding the resistor values necessary to implement this component in the provided scheme?
Thank you for all your help.
http://www.supertex.com/pdf/datasheets/DN2540.pdf
Alex
I am currently collecting material to complete the enginner's amp according to the specs available on the peter millet website.
Unfortunately the IXYS current regulator is unavailable in Italy (no chance whatsoever of finding it 🙁 ).
There is however the Supertex DN2540 which supposedly is a good substitute.
Could somone please help me finding the resistor values necessary to implement this component in the provided scheme?
Thank you for all your help.
http://www.supertex.com/pdf/datasheets/DN2540.pdf
Alex
hey-hey!!!,
Let me suggest using two in cascode. I have never found the single even close to the performance of the double. You'd need to hang the ccs underneath on a separate board, but that is the main difficulty IMO. Figure about 1.5V of bias voltage, and test with a 9V battery and a multi-meter set on current in series.
It is easiest to use the battery bias scheme, then the gate-source voltage is mostly the batteries, so 3.3V x 2 or 3 plus 1.5V and employ Ohm's law to determine the set resistor at the desired current.
cheers,
Douglas
Let me suggest using two in cascode. I have never found the single even close to the performance of the double. You'd need to hang the ccs underneath on a separate board, but that is the main difficulty IMO. Figure about 1.5V of bias voltage, and test with a 9V battery and a multi-meter set on current in series.
It is easiest to use the battery bias scheme, then the gate-source voltage is mostly the batteries, so 3.3V x 2 or 3 plus 1.5V and employ Ohm's law to determine the set resistor at the desired current.
cheers,
Douglas
http://www.audioxpress.com/magsdirx/ax/addenda/media/jung2779.pdf
Active loads and signal current control
Sorry this is above my head. But hey i can give info right?
Active loads and signal current control
Sorry this is above my head. But hey i can give info right?
@ Bandersnatch.... you actually employed the supertex in your own build? Could you provide resistance values and photos of your solution? Even a simple diagram would suffice and be very much appreciated. I am actually a selflearner and cascading is still beyond my grasp.
@Nightanole Thanks for the links. Interesting and informative. The cascading scheme seems cleare but again I really have a superficial understanding of the principles envolved. I am learning day by day but it is a stepp climb (especially if you are a aw student and not an engineer 😉 )
Thanks!
@Nightanole Thanks for the links. Interesting and informative. The cascading scheme seems cleare but again I really have a superficial understanding of the principles envolved. I am learning day by day but it is a stepp climb (especially if you are a aw student and not an engineer 😉 )
Thanks!
Though it's true the cascode performs better than a single DN2540... I'd argue that it's overkill here. A resistor works pretty well, and a single DN2540 is at least 100x as good as a resistor, no?
Then again, I've always LIKED a little unbalance in my designs 😛
Maybe it'd be a different story if this were a SE plate load...
Pete
I don't think that you could measure or hear the difference between a single 10M45, a single DN2540, or a cascode made out of two of anything in the cathode of an LTP at 10+ mA.
That has been debated for years. I have noticed that people who don't have an SSE often argue that it would work better with a cascode. A few, including myself have tried it and didn't find any obvious difference.
Does it really matter whether the dynamic impedance of the CCS is 1 megohms or 100 megohms when it is swamped by the 11K ohms plate resistance of the 12AT7 in parallel with the 120K grid bias resistor in the output stage?
The type of CCS makes no difference. The CCS set current multiplied by the voltage across it determines the power being dissipated. A cascode will spread the heat across two devices, although they don't share equally.
I have used the DN2540 in place of the 10M45 in a few places, but not in the red board. It would be possible to put a 500 ohm pot in in place of the current set resistor and adjust it for the desired current.