Fan of the old Revue de l'audiophile do not have particular interest in Nelson Pass design. I frankly do not know why. You are a rare breed !
Have started reading singing bush threads......looks like I need some boards.....any available?? Possibly Gerbers? thanks very much
Lottery P channel: https://www.firstwatt.com/pdf/art_diy_sony_vfet_pt1.pdf
Lottery N channel: https://www.firstwatt.com/pdf/art_diy_sony_vfet_pt2.pdf
OS2 for smaller Sony devices: https://www.diyaudio.com/community/threads/diy-sony-vfets-os2-official-thread.384256/
You can contact ZM directly for boards. Gerbers will not be available, to the best of my knowledge.
I am late in building chassis #147, with 2SJ28.
Now I have a question that started pondering me at night:
Now I have a question that started pondering me at night:
- If the 2SJ28 is best non-boosted, that is, without Mu-follower, but with a CCS @ 1.5A to 1.6Amp
- then would it be best suited for a choke load? Like Ben Mah for xample as source follower; or drain loaded (which I have with my 2SK182)?
- It will save me - 30 watts heating. And allow reducing the Vb from 36 to 25 volts.
- It can be self-biased on the choke if the choke has some resistance.
what are the advantages / disadvantages, apart from the cost, of an output transformer instead of a choke?
for proper reply, we need to speak about specific project/ pool of possible devices/parts
major decision fact is transfer characteristic of intended active device, so we can deduce which (ohmic value of) load is adequate
choke arrangement will allow your part to see (slightly bellow ) of ohmic value of your speaker (choke impedance practically in parallel with speaker impedance)
xformer should xform that to higher value (major role of xformer)
so, if part needs more ohms load than intended speaker is having, xformer is better solution than choke
anyhow - if chosen arrangement is allowing quick and dirt pool of parts ( say source follower with uwave xformer butchered to choke) everything is fine and good
if one needs something different - choke in Drain, things are getting much more complicated - you need impeccable PSU filtering, good or best quality choke, so no more lunch for free - all you can spare is some heat, while overall cost is going up up up
don't ask me how I know .............. recent playing with Choked Singing Bush did show me that there is no cheap choke solution, and that existing Singing Bush is cheaper overall - even if you need mos puck for mu, caps with higher voltage and bigger Donut and bigger chunk of Aluminum
in short - cheap choke only in source
major decision fact is transfer characteristic of intended active device, so we can deduce which (ohmic value of) load is adequate
choke arrangement will allow your part to see (slightly bellow ) of ohmic value of your speaker (choke impedance practically in parallel with speaker impedance)
xformer should xform that to higher value (major role of xformer)
so, if part needs more ohms load than intended speaker is having, xformer is better solution than choke
anyhow - if chosen arrangement is allowing quick and dirt pool of parts ( say source follower with uwave xformer butchered to choke) everything is fine and good
if one needs something different - choke in Drain, things are getting much more complicated - you need impeccable PSU filtering, good or best quality choke, so no more lunch for free - all you can spare is some heat, while overall cost is going up up up
don't ask me how I know .............. recent playing with Choked Singing Bush did show me that there is no cheap choke solution, and that existing Singing Bush is cheaper overall - even if you need mos puck for mu, caps with higher voltage and bigger Donut and bigger chunk of Aluminum
in short - cheap choke only in source
Many thanks for your answer. From your datas, VFET like 2sj18, 2sj28 or SIT like THF51S may they prefer a higher load than the 8/16 ohms of a speaker?
well, Sony and Tokin are really from different Kettles
now, Pa already covered know-how for small Sonys - re-read all recent articles and you'll find facts lined up better than I could line them up in one post
Tokins - there is only one choice - fact you're asking for is pretty much irrelevant - you're either going for choke loaded source follower (needing preamp with full voltage swing), or any other presented solution
my personal choices, listed by preference , are SissySIT, then Babelfish XA252 SIT
everything else (published here in Papaland) is greater number of compromises than I'm mood for, at least making choices by my own needs
now, what is best for you ....... read, think, read, think, build
now, Pa already covered know-how for small Sonys - re-read all recent articles and you'll find facts lined up better than I could line them up in one post
Tokins - there is only one choice - fact you're asking for is pretty much irrelevant - you're either going for choke loaded source follower (needing preamp with full voltage swing), or any other presented solution
my personal choices, listed by preference , are SissySIT, then Babelfish XA252 SIT
everything else (published here in Papaland) is greater number of compromises than I'm mood for, at least making choices by my own needs
now, what is best for you ....... read, think, read, think, build
@triode_al
I'm working on Choked Singing Bush - practically - as SIT is biased (Iq) withintegrated dedicated circuit, anything can be connected in Drain as load - either choke ( with output cap) or xformer or even resistors chain (with output cap) or even light bulbs chain (with output cap)
now, each variant needs to be optimized for Sweet Spot ( as Papa would say) regarding Iq and rail voltage .........
I can cover basic use - choke loading, under condition that crummy chokes I have are good enough for use with SIT; as I tried them (up to this moment) with Schade-d IXYS Puck, no go in that arrangement
anyway - do not count too much on finding ready recipe for circuit having SIT and output OPT - as you already know - proper OPT is expensive, and probability of someone doing exactly that, with OPT being good enough, while not costing arm and leg ...... is diminutive
that approach is certainly going to cost much more than OPT-less, while final results are not going to be better in any way; different yes, good yes, more liking to someone's personal taste yes, but not better thinking of general quality
I'm working on Choked Singing Bush - practically - as SIT is biased (Iq) with
now, each variant needs to be optimized for Sweet Spot ( as Papa would say) regarding Iq and rail voltage .........
I can cover basic use - choke loading, under condition that crummy chokes I have are good enough for use with SIT; as I tried them (up to this moment) with Schade-d IXYS Puck, no go in that arrangement
anyway - do not count too much on finding ready recipe for circuit having SIT and output OPT - as you already know - proper OPT is expensive, and probability of someone doing exactly that, with OPT being good enough, while not costing arm and leg ...... is diminutive
that approach is certainly going to cost much more than OPT-less, while final results are not going to be better in any way; different yes, good yes, more liking to someone's personal taste yes, but not better thinking of general quality
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Sharing some of my experience with choke loaded follower (SF) v mu-follower (MF):
1. If you are sitting on a lottery amp or OS2 with VFETs, then build it asap. You won’t be disappointed.
2. If you are looking at choke-loaded SF, go for it. I have been listening to one for over a year and it sounds great. There are plenty of chokes available, especially from Hammond. Look at Mike’s MoFo article. This amp is very easy to build with a minimum number of parts and really lets you hear the VFET. You have to provide a preamp with some balls to drive it effectively.
Main point is jump in and build something. These VFETs are amazing devices.
1. If you are sitting on a lottery amp or OS2 with VFETs, then build it asap. You won’t be disappointed.
2. If you are looking at choke-loaded SF, go for it. I have been listening to one for over a year and it sounds great. There are plenty of chokes available, especially from Hammond. Look at Mike’s MoFo article. This amp is very easy to build with a minimum number of parts and really lets you hear the VFET. You have to provide a preamp with some balls to drive it effectively.
Main point is jump in and build something. These VFETs are amazing devices.
If you decide to include any of the twelve VFET Front End cards found on this site, within your VFET amplifier chassis . . . . . then your preamp only needs to output about 3 volts (RMS) to get max power / onset of clipping. That's not a giant amount of balls : each of the Front End cards has a gain of 5X (+14 dB).
Search terms: Scourge, Marauder, Bulwark, Dreadnought, Lexington, Missouri, Nimitz, Bon Homme Richard, Kitty Hawk, Hornet, Pequod, Front End
I've just finished putting together my one of these with 2SJ18s in and I have an issue with a very quiet channel....
I've switched the output and input cables around, so it's definitely the left channel. I recleaned the boards incase a piece of flux was causing an issue, no obvious bad solder joints either. I disconnected and reconnected the wiring with no luck.
I don't suppose could help with any ideas on what to check next? It biased up fine and the other channel sounds great, no hum or hiss either, just very, very quiet.
I would say, it's my first amplifier build so there is a bit of potential for me doing something a little daft
I've switched the output and input cables around, so it's definitely the left channel. I recleaned the boards incase a piece of flux was causing an issue, no obvious bad solder joints either. I disconnected and reconnected the wiring with no luck.
I don't suppose could help with any ideas on what to check next? It biased up fine and the other channel sounds great, no hum or hiss either, just very, very quiet.
I would say, it's my first amplifier build so there is a bit of potential for me doing something a little daft