Hi guys.
I rarely send posts, but I thought I would share this small project since it brought me so much fun, and musical enjoyment.
I know that tiny SE-Triode amps are not favored by the majority, but for those of you who happen to own (and apreciate) reasonably efficient speakers, this amp is lively, 3D and a real pleasure to live with.
I'm not knowledgeable alot about technology, but I'm learning.. So far, I've built a fairly nice 300B SE amp, a couple of 2A3 amps, and a Gainclone. All successful, and in no way, do I miss my previous Audionote 300B, neither my Audio Research (D70 yuk) or CJ.
This amp is the Shishido (loffin-white) 2A3.
Link: http://www3.sympatico.ca/wenchieh/2A3_schematics/shishido.jpg
It's easy to build. Almost no parts. I had build it with huge Hamonds 1627SE Output trannies, but lately I ordered 125FSE trannies, so I can substitute output tubes for 45 and WOW. Ok, it can play almost loud enough for most stuff. (with my Tannoys, and with Castle Chester) not very LOUD, but very adequate for every day use.
My 300B is the best "compromise", followed by the 2A3, but I must admit that with the 45s, everything lock in place, 3D image, timber naturalness, focus. A feeling of being there, especially on guitars, and on piano too. In fact, I love so much this amp, I might dig out my big 15" to see how it matches.
Well, this is it. I'm just excited at the idea of listening more and more music with it. A nice find, and by the way, these little Hammond FSE125 are real gems for a cheap price.
I rarely send posts, but I thought I would share this small project since it brought me so much fun, and musical enjoyment.
I know that tiny SE-Triode amps are not favored by the majority, but for those of you who happen to own (and apreciate) reasonably efficient speakers, this amp is lively, 3D and a real pleasure to live with.
I'm not knowledgeable alot about technology, but I'm learning.. So far, I've built a fairly nice 300B SE amp, a couple of 2A3 amps, and a Gainclone. All successful, and in no way, do I miss my previous Audionote 300B, neither my Audio Research (D70 yuk) or CJ.
This amp is the Shishido (loffin-white) 2A3.
Link: http://www3.sympatico.ca/wenchieh/2A3_schematics/shishido.jpg
It's easy to build. Almost no parts. I had build it with huge Hamonds 1627SE Output trannies, but lately I ordered 125FSE trannies, so I can substitute output tubes for 45 and WOW. Ok, it can play almost loud enough for most stuff. (with my Tannoys, and with Castle Chester) not very LOUD, but very adequate for every day use.
My 300B is the best "compromise", followed by the 2A3, but I must admit that with the 45s, everything lock in place, 3D image, timber naturalness, focus. A feeling of being there, especially on guitars, and on piano too. In fact, I love so much this amp, I might dig out my big 15" to see how it matches.
Well, this is it. I'm just excited at the idea of listening more and more music with it. A nice find, and by the way, these little Hammond FSE125 are real gems for a cheap price.
p.s
About the trannies..
Since these trannies offer multiple impedances matches, I've added a togle switch on my amp, switching bias resistors easily. So, I can remove the 2A3, put the 45 in and switch to the right bias. Very useful.
About the trannies..
Since these trannies offer multiple impedances matches, I've added a togle switch on my amp, switching bias resistors easily. So, I can remove the 2A3, put the 45 in and switch to the right bias. Very useful.
Sylvain,
Direct connect amps are nice, I’m glad you are enjoying yours. Given the filament demand of 45, 2A3 and 300B are so different I expect you are running your filaments AC with the filament transformers on a variac so you can dial up the filament voltage that is needed. If you get a hold of some 4-pin plugs and wire a loctal socket base to them you can plug Russian 4L1P tubes in, they bias up fine in 2A3 amps, just something else to try. You can get a handful of 4L1Ps for what you are paying for your 45s and 2A3s.
Matt
Direct connect amps are nice, I’m glad you are enjoying yours. Given the filament demand of 45, 2A3 and 300B are so different I expect you are running your filaments AC with the filament transformers on a variac so you can dial up the filament voltage that is needed. If you get a hold of some 4-pin plugs and wire a loctal socket base to them you can plug Russian 4L1P tubes in, they bias up fine in 2A3 amps, just something else to try. You can get a handful of 4L1Ps for what you are paying for your 45s and 2A3s.
Matt
Hello Matt,
If you re-read my post carefully, you'll realise that I have built "both" a 300B amp, and the 2A3/45 amp.
The 300B is built after the Morrison FiPrimer schematic (cap coupled) and the 2A3/45 DC coupled.
Yes, I do enjoy so much DC coupling that I might try to turn the 300B amp into Loftin-White too.. after I've tried a interstage coupled version. (Black Art trannies)
What Direct Coupled amps are you listening to?
Sylvain
If you re-read my post carefully, you'll realise that I have built "both" a 300B amp, and the 2A3/45 amp.
The 300B is built after the Morrison FiPrimer schematic (cap coupled) and the 2A3/45 DC coupled.
Yes, I do enjoy so much DC coupling that I might try to turn the 300B amp into Loftin-White too.. after I've tried a interstage coupled version. (Black Art trannies)
What Direct Coupled amps are you listening to?
Sylvain
By the way, I listened to it again last night, and the 45 (n.o.s. National Union NU)have so much more focus and naturalness than 2A3 (n.o.s. RCA biplate) I wish I could afford 2A3 monoplate..
Sylvain,
The 6EM7 is my desktop amp right now and the P-P is on the main system. On some other amps I have the filament transformers on variacs allowing easy tube swapping. I have never heard vintage 2A3s I'm sure they are nice.
Matt
The 6EM7 is my desktop amp right now and the P-P is on the main system. On some other amps I have the filament transformers on variacs allowing easy tube swapping. I have never heard vintage 2A3s I'm sure they are nice.
Matt
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Hello Matt,
Your little 6EM7 amp seems quite fun. I like simple audio paths. I'm sure it sounds good. How many watts? ;-) I guess my 45 amp is 1.5watt! but it drives my Tannoys at reasonable level. The 300B is much more at ease..
I'll try to post pics of my amps.
What kind of speakers do you use?
Your little 6EM7 amp seems quite fun. I like simple audio paths. I'm sure it sounds good. How many watts? ;-) I guess my 45 amp is 1.5watt! but it drives my Tannoys at reasonable level. The 300B is much more at ease..
I'll try to post pics of my amps.
What kind of speakers do you use?
Sylvain,
I guess I could be getting 2.5 watts or so out of the 6EM7, I've never bothered to calculate it. I'm listening to a pair of Fostex P800E DIY Kanspea 3" Full Range with FE83En drivers I borrowed from a friend, driven by that 6EM7 amp. Near-field listening is a must with that little set up.
Matt
I guess I could be getting 2.5 watts or so out of the 6EM7, I've never bothered to calculate it. I'm listening to a pair of Fostex P800E DIY Kanspea 3" Full Range with FE83En drivers I borrowed from a friend, driven by that 6EM7 amp. Near-field listening is a must with that little set up.
Matt
Hi Matt,
The Tannoys are around 94db efficient, so, I'm surprised at how confortable the little 45 amp is confortable to listen to. At "reasonable" levels, of course. Voices are wonderful.. humm
I read that your FE83En are only 88db/1W efficient.. It doesn't leave you much margin.
I equally have a pair of Klipsch KG4, 94db eff too. I have recently seen a pair of Klipsch Tangent for $90 in a pawn shop. I guess you'd be amazed at how much headroom these 6db more would help.
I have a friend who bought "Alpair" drivers. They look alot like your Fostex. Very nice 3D imaging..
For now, I can't wait at getting the best of my actual amps.
The Tannoys are around 94db efficient, so, I'm surprised at how confortable the little 45 amp is confortable to listen to. At "reasonable" levels, of course. Voices are wonderful.. humm
I read that your FE83En are only 88db/1W efficient.. It doesn't leave you much margin.
I equally have a pair of Klipsch KG4, 94db eff too. I have recently seen a pair of Klipsch Tangent for $90 in a pawn shop. I guess you'd be amazed at how much headroom these 6db more would help.
I have a friend who bought "Alpair" drivers. They look alot like your Fostex. Very nice 3D imaging..
For now, I can't wait at getting the best of my actual amps.
About the cathode resistor
On schematics says 3000 Ohms for 2A3, for 45 tube swing how many the cathode resistor can be?
Plus the change on OPT impedance, any other change on sch for 45 tube?
On schematics says 3000 Ohms for 2A3, for 45 tube swing how many the cathode resistor can be?
Plus the change on OPT impedance, any other change on sch for 45 tube?
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I have a JJ 2A3-40 which I've yet to use, did you have a chance to listen to other brands of 2A3 ?
Matt,
That 6EM7 amplifier looks brilliant....wish more tubes would lend themselves to such a circuit !
That 6EM7 amplifier looks brilliant....wish more tubes would lend themselves to such a circuit !
can you use dc on filament of 2A3 and omit the hum pot 50ohm (series resistors 20/20 and vr10ohm)? does it hum using AC on filaments?
Construction and connection of heating wires inside is special for self compensating of 50-60 Hz.
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I noted Telefunken high voltage tube RV 278 works with AC 10 V in most amps before II WW. /I'm looking for 1 used tube to borrow, because I have only one RV278 - it's very expensive - for my experiment/. This tube is closed to 211, 845, GM....Sorry for off.
2A3 and AC filament
Over the years I've tested about 60 different 2A3 tubes, mostly the newer dual-triode types from RCA, Sylvania, Philco, Ken-Rad, Zenith... all NOS. I also have a quartet of RCA/Cunningham Single-Plate 2A3 tubes which I've tested.
In short, the newer dual types can be used with AC filaments and a hum pot to get reasonable signal-to-noise levels. You will find some pretty significant variation however... literally 10dB or more spread. On a really good pair you can expect upwards of 80dB referenced to 1-watt output, but that's a small percentage of a larger quantity.
The single-plate version must be used with a DC filament supply. The filament in the single-plate is very different as it uses many vertical wires arranged in two parallel sets which are side-by-side. The two parallel sets are then connected in parallel with the center points tied together and the outer end points tied together (basically a center-tapped arrangement similar to the WE300b). As a result, s/n with these tubes on AC filaments is horrible, and the scope pattern is bizarre... no way to get them even close to reasonable/listenable with AC heating.
My personal choice, hands down are the earlier Sylvania dual types (either coil-spring top tensioners or the later fishing pole type tensioners)... I find them superior to the coveted RCA versions. The internals are much more robust, they are far less prone to mechanical excitation and always measure better for THD and hum nulling (assuming good samples of all brands). Also note that Zenith tubes were generally sourced from Sylvania as RCA was a competitor in the product space. I've also found them to be extremely tight on tolerances which makes me believe that Zenith had a narrow spec to meet when purchasing.
Regards, KM
Over the years I've tested about 60 different 2A3 tubes, mostly the newer dual-triode types from RCA, Sylvania, Philco, Ken-Rad, Zenith... all NOS. I also have a quartet of RCA/Cunningham Single-Plate 2A3 tubes which I've tested.
In short, the newer dual types can be used with AC filaments and a hum pot to get reasonable signal-to-noise levels. You will find some pretty significant variation however... literally 10dB or more spread. On a really good pair you can expect upwards of 80dB referenced to 1-watt output, but that's a small percentage of a larger quantity.
The single-plate version must be used with a DC filament supply. The filament in the single-plate is very different as it uses many vertical wires arranged in two parallel sets which are side-by-side. The two parallel sets are then connected in parallel with the center points tied together and the outer end points tied together (basically a center-tapped arrangement similar to the WE300b). As a result, s/n with these tubes on AC filaments is horrible, and the scope pattern is bizarre... no way to get them even close to reasonable/listenable with AC heating.
My personal choice, hands down are the earlier Sylvania dual types (either coil-spring top tensioners or the later fishing pole type tensioners)... I find them superior to the coveted RCA versions. The internals are much more robust, they are far less prone to mechanical excitation and always measure better for THD and hum nulling (assuming good samples of all brands). Also note that Zenith tubes were generally sourced from Sylvania as RCA was a competitor in the product space. I've also found them to be extremely tight on tolerances which makes me believe that Zenith had a narrow spec to meet when purchasing.
Regards, KM