Is there such a thing as a practical use of a VFET in a headamp? I mean we are seeing every other design get morphed into an headphone amp design - Aleph, F4, F5 and even the J2 isn't immune (ACP+).
Perhaps the Tokin parts are just too much of a wild beast for offset stability, making it less suitable but what about IXYS or Cree or even Lovoltech and Semisouth parts?
Just thinking out loud here as I've already surpassed my brain capacity but thought it might be worth asking.
I think EUVL's DAO uses the LU1014D in a headamp - would that impart the classic SIT sound that you get in a SIT/DEFiSIT/SissySIT/BAF2015?
While I have your attention, is there any reason why TO-247 and similar size package devices are not used in headphone amps while TO-220 are the norm? Is it simply not efficient at such low current to use the bigger devices?
I know some people use power amps as headphone amps for the really hard to drive cans but I cant afford that problem unfortunately. I'm thinking of the more commonly seen headphones like the AKG Q701 and HifiMan HE400i among others.
Would the most appropriate and easiest approach be to take EUVL's UDNESS with the servo and stick some VFETs in with reduced power? Would that be too much like the ACP+ and not enough of a SIT?
Perhaps the Tokin parts are just too much of a wild beast for offset stability, making it less suitable but what about IXYS or Cree or even Lovoltech and Semisouth parts?
Just thinking out loud here as I've already surpassed my brain capacity but thought it might be worth asking.
I think EUVL's DAO uses the LU1014D in a headamp - would that impart the classic SIT sound that you get in a SIT/DEFiSIT/SissySIT/BAF2015?
While I have your attention, is there any reason why TO-247 and similar size package devices are not used in headphone amps while TO-220 are the norm? Is it simply not efficient at such low current to use the bigger devices?
I know some people use power amps as headphone amps for the really hard to drive cans but I cant afford that problem unfortunately. I'm thinking of the more commonly seen headphones like the AKG Q701 and HifiMan HE400i among others.
Would the most appropriate and easiest approach be to take EUVL's UDNESS with the servo and stick some VFETs in with reduced power? Would that be too much like the ACP+ and not enough of a SIT?
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Here's a Vfet preamp by Uncle Mike:
https://audioxpress.com/assets/upload/files/AXApri2014_LuminAria SIT Preamp.pdf
https://audioxpress.com/assets/upload/files/AXApri2014_LuminAria SIT Preamp.pdf
> is there any reason why TO-247 and similar size package devices are not used in headphone amps while TO-220 are the norm? Is it simply not efficient at such low current to use the bigger devices?
Is there any reason 427 cubic inch engines are not used in urban coupes? Instead they all use 90-120 CI engines?
Even ignoring fuel-cost or tax and insurance, sending a big lump to do a small lump's job means it may be less nimble and agile.
Yes, they "could" pack just a TO220 worth of sand in a TO247 or even a TO3 package, but why?
Any active device that can pass 100mA and throw >1 Watt "can" be a headphone amp. Cathode Follower is usually sufficient. Too clean? Too bad!
Is there any reason 427 cubic inch engines are not used in urban coupes? Instead they all use 90-120 CI engines?
Even ignoring fuel-cost or tax and insurance, sending a big lump to do a small lump's job means it may be less nimble and agile.
Yes, they "could" pack just a TO220 worth of sand in a TO247 or even a TO3 package, but why?
Any active device that can pass 100mA and throw >1 Watt "can" be a headphone amp. Cathode Follower is usually sufficient. Too clean? Too bad!
Thank you for the lesson PRR!
Thanks for the link to the Luminaria Dennis!
I remembered the reference in MR's article to input capacitance being an issue to overcome for a preamp application and see now the massive difference in CISS between an IRF610 (140) and an IRFP240 (1300). Is that (one of) the deciding factors that favor the smaller devices in preamps and headamps?
SIT driver
with some times to spend , can i use a Sony Sit 2SK60 or 2SK82 at high voltage ( 150 / 200V) and low current ( 20 /50ma) to drive a 300B in a SET amplifier? i have already try the Vfet with an output transformer with a low voltage and high current on my Nemesis but never at high voltage.
any spice master to help me in this craziness ? 😀
with some times to spend , can i use a Sony Sit 2SK60 or 2SK82 at high voltage ( 150 / 200V) and low current ( 20 /50ma) to drive a 300B in a SET amplifier? i have already try the Vfet with an output transformer with a low voltage and high current on my Nemesis but never at high voltage.
any spice master to help me in this craziness ? 😀
I have built L'Amp: A simple SIT Amp for my HD800, and I must say, it's magnificent.
It's huge, it's heavy, it's overkill, it gets hot. In other words, perfect.
The last pic gives you an idea about the actual size of the amp...
It's huge, it's heavy, it's overkill, it gets hot. In other words, perfect.
The last pic gives you an idea about the actual size of the amp...
Attachments
😎 Fantastic ! even if the CCS load or inductor load SITAMP mesure better , the Resistor or Bulb Sitamp is still my favorite in winter days 🙂
Jims Audio on eBay has genuine LU1014D. They would make a great SIT headamp. The price is USD $8.49 for 2 pcs. I have curve traced enough of them to be satisfied of authenticity.
Only caveat is that 2 pcs were duds. Jim replaced the duds on a subsequent order.
Only caveat is that 2 pcs were duds. Jim replaced the duds on a subsequent order.
Yes, resistor loaded SIT amps is phantastique, and the best part is I can fully understand how the amp is working. 🙂
Hey Twitchie,
I imagine CISS and whatnot come into play.
Of course, that never stopped Papa from using IRF244 (TO3 package, baby!)
in the original Aleph P. 😀😀😀
I imagine CISS and whatnot come into play.
Of course, that never stopped Papa from using IRF244 (TO3 package, baby!)
in the original Aleph P. 😀😀😀
I have been trying to design 300V/50mA 2SJ28 balanced input gain stage for 2SK182ES ALL SIT SE amp. It seems to be working well at least on Spice, but SONY SIT would be too low gain for 300B... (Why 2SJ28? Because I have them. 🙂)
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Rodeodave, I did follow your updates in the L'Amp thread and thoroughly enjoy admiring your creation again 
I have a quad of 300W bulbs in my pile and found myself well in over my head because I was hearing that I would need to trace my particular devices (not Sony VFETS) and do the load line/sweet spot calculations to do it properly and then surrendered the attempt at that point.
I will go back and re-read as much as I can and may attempt SIT L'amp again one day but probably not for a headphone amp ...
How about the dumb, lazy man's approach - Aleph Mini with substitute SIT in place of mosfet? Aleph-H with Cree or IXYS substitutes (because I have a bunch of them)? Doomed to fail even before starting? Should it have SIT flavor?
I have a dozen+ Lovoltech's from Grey's group buy, no shortage of parts, just shortage of smarts (because it rhymes).
I have a quad of 300W bulbs in my pile and found myself well in over my head because I was hearing that I would need to trace my particular devices (not Sony VFETS) and do the load line/sweet spot calculations to do it properly and then surrendered the attempt at that point.
I will go back and re-read as much as I can and may attempt SIT L'amp again one day but probably not for a headphone amp ...
How about the dumb, lazy man's approach - Aleph Mini with substitute SIT in place of mosfet? Aleph-H with Cree or IXYS substitutes (because I have a bunch of them)? Doomed to fail even before starting? Should it have SIT flavor?
I have a dozen+ Lovoltech's from Grey's group buy, no shortage of parts, just shortage of smarts (because it rhymes).
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