The general thoughts I'm picking up is that the Output Transformer is te key ingrediant in a SE 300B design.
Would some of you care to comment about the virtues of some of the beter known brands.
Hammond
Piltron
Tamura
Tango
Smaller suppliers
I'm thinking Tamura cause I want to do this once and they seem to have the best rep so far but their cost is several times that of a Hammond.
On smaller suppliers that you can't get a reference for eg I tried with Black Art OTF but no one has used them. How do I know if the TF is any good - its a bit expensive to "give it a try".
Please discuss and Many Thanks
Would some of you care to comment about the virtues of some of the beter known brands.
Hammond
Piltron
Tamura
Tango
Smaller suppliers
I'm thinking Tamura cause I want to do this once and they seem to have the best rep so far but their cost is several times that of a Hammond.
On smaller suppliers that you can't get a reference for eg I tried with Black Art OTF but no one has used them. How do I know if the TF is any good - its a bit expensive to "give it a try".
Please discuss and Many Thanks
I ordered mine from Sowter. Unbelievably good service and even better transformers. You can't go wrong with Sowter! 
www.sowter.co.uk
www.sowter.co.uk
Odd rambling reply ...
First, 'DVDHack', how about letting us know your first name; DVDHack is so impersonal!
Some may argue against the OPT being 'the' single most important aspect of a SET, but I think all will accept its importance.
The problem with your request is that few of us have been able to do much direct comparison, as good OPTs are expensive. So you may have to gather as much info as you can, of whatever type, and filter it; that's what I did.
My experience is limited to ONE 300B SET, and ONE type of OPT, so what the hell do I know?
Well, that OPT is Lundahl, and results are excellent. No way can I say it's the best, I just don't know.
I suggest you research the point here; and also on Tube DIY Asylum where you'll find hundreds of posts ... most saying their choice is the best, which is where you have to apply that filter.
I have some specific points for you to consider.
Bandwidth:
It's suggested that, when plotted logarithmically, the total bandwidth of most good OPTs is surprisingly similar in magnitude.
Comparing two with upper limits of say 30kHz and 60kHz, you'll often find that the second one has a higher low frequency cutoff. So don't just take an impressive hf figure as a single figure of merit.
Specifications:
Of somewhat dubious value! It depends how the measurements were done. Possibly, measuring an OPT at very low power can give very high upper frequency measurements that cannot be met in use.
So, reliable descriptions of sound 'character' may be of more use.
Impedance:
Many designs use about 3kohm, perhaps 2.5kohm, impedance for a 300B. However, there can be benefits from using a higher impedance of say 5kohm; less distortion.
However, a lower impedance of say 3k will give more power. About 8 watts. I guess it's often used by professionals as, if the 300B's are run hard, they can just about claim 10 watts (at say 10% thd) and double figures has *so* much more street cred than a single figure wpc!
A 5kohm OPT will give about 6.5 watts at the point of clipping, compared to 8 watts or 8.5 with 3kohm. Possibly a good trade off for less distortion; something to consider, as the difference between 6.5 and 8.5 is really not a lot.
Oh, and 6.5 watts of pure SET sound, delivered from a really solid PSU, is a hell of a sight more powerful than you'd expect.
Good luck; keep feeding us your ideas.
First, 'DVDHack', how about letting us know your first name; DVDHack is so impersonal!
Some may argue against the OPT being 'the' single most important aspect of a SET, but I think all will accept its importance.
The problem with your request is that few of us have been able to do much direct comparison, as good OPTs are expensive. So you may have to gather as much info as you can, of whatever type, and filter it; that's what I did.
My experience is limited to ONE 300B SET, and ONE type of OPT, so what the hell do I know?
Well, that OPT is Lundahl, and results are excellent. No way can I say it's the best, I just don't know.
I suggest you research the point here; and also on Tube DIY Asylum where you'll find hundreds of posts ... most saying their choice is the best, which is where you have to apply that filter.
I have some specific points for you to consider.
Bandwidth:
It's suggested that, when plotted logarithmically, the total bandwidth of most good OPTs is surprisingly similar in magnitude.
Comparing two with upper limits of say 30kHz and 60kHz, you'll often find that the second one has a higher low frequency cutoff. So don't just take an impressive hf figure as a single figure of merit.
Specifications:
Of somewhat dubious value! It depends how the measurements were done. Possibly, measuring an OPT at very low power can give very high upper frequency measurements that cannot be met in use.
So, reliable descriptions of sound 'character' may be of more use.
Impedance:
Many designs use about 3kohm, perhaps 2.5kohm, impedance for a 300B. However, there can be benefits from using a higher impedance of say 5kohm; less distortion.
However, a lower impedance of say 3k will give more power. About 8 watts. I guess it's often used by professionals as, if the 300B's are run hard, they can just about claim 10 watts (at say 10% thd) and double figures has *so* much more street cred than a single figure wpc!
A 5kohm OPT will give about 6.5 watts at the point of clipping, compared to 8 watts or 8.5 with 3kohm. Possibly a good trade off for less distortion; something to consider, as the difference between 6.5 and 8.5 is really not a lot.
Oh, and 6.5 watts of pure SET sound, delivered from a really solid PSU, is a hell of a sight more powerful than you'd expect.
Good luck; keep feeding us your ideas.
Well that's two for Sowter at least.
I take your point on lack of comparability unless you've owned a few but I got the impression that several people had gone through the process of Hammond and Piltron etc and formed an opinion.
There are references on the web stating people had "upgraded" their amp with better OTF but how do they know they are upgrading unless there is some sort of quality hierarchy?
I can't readily compare the sound so I am concerned I may miss the potential of Valve without ever realising it. I could spend a great deal on poor components and never realise.
Regards
Ralf
I take your point on lack of comparability unless you've owned a few but I got the impression that several people had gone through the process of Hammond and Piltron etc and formed an opinion.
There are references on the web stating people had "upgraded" their amp with better OTF but how do they know they are upgrading unless there is some sort of quality hierarchy?
I can't readily compare the sound so I am concerned I may miss the potential of Valve without ever realising it. I could spend a great deal on poor components and never realise.
Regards
Ralf
Hola Ralf,
Try Lundahl. They are excellent and quite reasonably priced, and there is an Australian distributor who's good to deal with. As there is a shipment about to arrive (I have another order in), there may be a 4 week leadtime if you ordered them soon. I've tried the Hammond PP varieties and they suck compared to the Lundahls. I've used lots of them, and compared them to a number of other brands, so I have a good reference point to comment from*.
www.lundahl.se , specifically the 1663 (3k:8), probably around $A250ea (BUT check the pricing with Control Audio)
Control Audio Pty Ltd
Mr. Rick Dowel
Level 6, Westfield Towers
100 William Street
AU-Sydney NSW 2000
Australia
Phone +61 - (0)2 - 9368 7100
Fax +61 - (0)2 - 9368 7199
Email: sales@controldevices.net
A second choice, and another one to recommend is Lancroft.
http://www.users.bigpond.com/triode/
triode@bigpond.com
I have some of these too, and they're excellent.
* Caveat: can't give specific advice on SE OPT's as I don't build SE amps, but have built lots of PP's.
Try Lundahl. They are excellent and quite reasonably priced, and there is an Australian distributor who's good to deal with. As there is a shipment about to arrive (I have another order in), there may be a 4 week leadtime if you ordered them soon. I've tried the Hammond PP varieties and they suck compared to the Lundahls. I've used lots of them, and compared them to a number of other brands, so I have a good reference point to comment from*.
www.lundahl.se , specifically the 1663 (3k:8), probably around $A250ea (BUT check the pricing with Control Audio)
Control Audio Pty Ltd
Mr. Rick Dowel
Level 6, Westfield Towers
100 William Street
AU-Sydney NSW 2000
Australia
Phone +61 - (0)2 - 9368 7100
Fax +61 - (0)2 - 9368 7199
Email: sales@controldevices.net
A second choice, and another one to recommend is Lancroft.
http://www.users.bigpond.com/triode/
triode@bigpond.com
I have some of these too, and they're excellent.
* Caveat: can't give specific advice on SE OPT's as I don't build SE amps, but have built lots of PP's.
Suggestions
These brands seem to have a good reputation:
Tamura, Tango, Magnequest, Lundahl, Plitron, SJS (used by Border Patrol).
At this level, differences in performance are probably not going to be great, and may be explained to some extent by how the passband is set relative to the audio spectrum; some oriental models with extended high frequency may, possibly, have a less extended bottom end. You may be able to make an intelligent choice if aware of this.
I tend to suggest that Lundahl set the passband pretty evenly on the spectrum, favouring neither highs nor lows. In conjunction with a 300B with extended top and bottom (TJ mesh plates), results seem good to me.
There are two suppliers in the Netherlands who produce amorphous core OPTs that appear to be of very high quality, worth a bit of research. I am very tempted to try these myself in a new SET project .... possibly to be called 'Sindy' and I'm sure people can guess why.
Given the lowish dollar, you might check pricing on the better ones from the USA?
Or see what's going on US Ebay for the far eastern makes (but avoid one particular US seller with many adverse comments on Tube DIY Asylum!).
These brands seem to have a good reputation:
Tamura, Tango, Magnequest, Lundahl, Plitron, SJS (used by Border Patrol).
At this level, differences in performance are probably not going to be great, and may be explained to some extent by how the passband is set relative to the audio spectrum; some oriental models with extended high frequency may, possibly, have a less extended bottom end. You may be able to make an intelligent choice if aware of this.
I tend to suggest that Lundahl set the passband pretty evenly on the spectrum, favouring neither highs nor lows. In conjunction with a 300B with extended top and bottom (TJ mesh plates), results seem good to me.
There are two suppliers in the Netherlands who produce amorphous core OPTs that appear to be of very high quality, worth a bit of research. I am very tempted to try these myself in a new SET project .... possibly to be called 'Sindy' and I'm sure people can guess why.
Given the lowish dollar, you might check pricing on the better ones from the USA?
Or see what's going on US Ebay for the far eastern makes (but avoid one particular US seller with many adverse comments on Tube DIY Asylum!).
Tamura sell for $1600US at Angela while Tango are $600, is the difference warranted? Is price a good indicator between brands?
So far Sowter appear to have great support.
Seems Tubes are earsier - everyone says the WE are the best - what ever that means.
At this stage I'm leaning toward Sowter or Lumdahl due to the support here. I am also considering Black Art here in Australia. I've emailed the guy from Black Art to send me a phone number to contact him on but he hasn't responded in a few days. But it is that time of year - if he doesn't respond then I probably don't want to deal with him anyway.
Thanks for all your help
Ralf
So far Sowter appear to have great support.
Seems Tubes are earsier - everyone says the WE are the best - what ever that means.
At this stage I'm leaning toward Sowter or Lumdahl due to the support here. I am also considering Black Art here in Australia. I've emailed the guy from Black Art to send me a phone number to contact him on but he hasn't responded in a few days. But it is that time of year - if he doesn't respond then I probably don't want to deal with him anyway.
Thanks for all your help
Ralf
One Electron. Model UBT-3.
Far superior to the Hammond for the same price.
Only available from Antique Electronic Supply
http://www.tubesandmore.com
It is what I use in my kits.
Specs? <10 Hz to >40KHz. Very clean and linear response. Very lifelike. Very sweet. The 300B/OE combo is astonishing. I also used the Hammond for testing. Hammond sounded sweet, but not quite as open. Hammonds sounded kind of dark. OE just right.
Gabe
Far superior to the Hammond for the same price.
Only available from Antique Electronic Supply
http://www.tubesandmore.com
It is what I use in my kits.
Specs? <10 Hz to >40KHz. Very clean and linear response. Very lifelike. Very sweet. The 300B/OE combo is astonishing. I also used the Hammond for testing. Hammond sounded sweet, but not quite as open. Hammonds sounded kind of dark. OE just right.
Gabe
Most who have tried the Lundahl transformers, appear to be very satisfied with them.
I also seem to recall that Andrea Cuifolli (?) uses them exclusively, and that the Lundahl site has some construction ideas based on their trannies, developed by the recording/mixing/mastering guy at the music conservatorium at a Danish university, and used as his reference when mastering.
You might want to consider using a SV572-3 instead of the 300B (my asbestos is ready ). With a 5k:8 transformer from Lundahl, rated at 25W (the SV572-3 will generate 24W single ended), you would have a pretty darn good match.
And, yes, I have heard both the SV572-3 and the 300B used in successful constructions. I found the SV572-3 to be truer to the source, while the 300B has more of the 'doris day filter' effect that so many valve enthusiasts seem to go for.
(And, yes, I consider myself a valve enthusiast, I just happen to be in the camp that considers neutrality the goal, with valves just being a convenient way to approach that goal from the 'pleasing' end of the spectrum, rather than the 'harsh' end of the spectrum.)
As far as "typical" valve sound goes, it is worth pointing out that SE (or valves, for that matter) is not the only way to acheive it. For example, Electrocompaniet, are famous for their valve-like mids, despite using balanced symmetric push-pull transistor amplifiers.
I also seem to recall that Andrea Cuifolli (?) uses them exclusively, and that the Lundahl site has some construction ideas based on their trannies, developed by the recording/mixing/mastering guy at the music conservatorium at a Danish university, and used as his reference when mastering.
You might want to consider using a SV572-3 instead of the 300B (my asbestos is ready
). With a 5k:8 transformer from Lundahl, rated at 25W (the SV572-3 will generate 24W single ended), you would have a pretty darn good match.And, yes, I have heard both the SV572-3 and the 300B used in successful constructions. I found the SV572-3 to be truer to the source, while the 300B has more of the 'doris day filter' effect that so many valve enthusiasts seem to go for.
(And, yes, I consider myself a valve enthusiast, I just happen to be in the camp that considers neutrality the goal, with valves just being a convenient way to approach that goal from the 'pleasing' end of the spectrum, rather than the 'harsh' end of the spectrum.)
As far as "typical" valve sound goes, it is worth pointing out that SE (or valves, for that matter) is not the only way to acheive it. For example, Electrocompaniet, are famous for their valve-like mids, despite using balanced symmetric push-pull transistor amplifiers.
Hi, fdegrove.
I'm glad we agree as far as 'valve sound' is concerned. I get very frustrated by the fact that there are two distinct camps in the valve community, that appear to consider themselves a coherent whole, and more relevantly, by the fact that most reviews tend to be from a listener in one of the camps, disregarding the fact that the people in the other camp are not looking for the same thing.
Perhaps some term needs to be coined, referring to the magic of valves when used to produce neutral sound, as opposed to the so called 'valve sound', a term often used to refer to sound that is anything but neutral, frequently resulting from using nonlinear valves at nonideal operating points with substandard output trannies.
How about 'valve fidelity' ?
Anyway, as to the Electrocompaniet amplifiers, I was not referring to the soundstage, but rather the tonal balance and midrange lucidity.
And, no, I am not one of their proponents, just stating what I've seen people say about them in the hifi press. For the price, they deliver sensible goods, but I think the tonal balance of their entry level amplifiers is a bit too much off, and the sound stage becomes a bit too onedimensional for my taste. Can't exactly call them bad, though, considering the price. I have no experience with their high end products, though, so I cannot contribute any opinions of my own there.
Certainly, the EC1 is not a contender for the high end. However, I hear the Nemo (600W monoblock) is one of the most neutral power stages around. Stereophile, as usual, gave it rather high praise.
The CD player seemed nice, though, last time I listened to it.
On a side note, the Nemo was originally prototyped under the name 'Enigma', in possibly the coolest enclosure I've ever seen. It was a cube in clear aluminum, with the top having the raised, crisscrossing grooves you typically see used for traction on industrial stairs or trucks. And there was a sunken-in, rounded triangle on the front, ending in black acrylic with the characteristic 'E' on it. Weighed a bunch, generated tons of heat, and output a kilowatt or so with high bias.
I'm glad we agree as far as 'valve sound' is concerned. I get very frustrated by the fact that there are two distinct camps in the valve community, that appear to consider themselves a coherent whole, and more relevantly, by the fact that most reviews tend to be from a listener in one of the camps, disregarding the fact that the people in the other camp are not looking for the same thing.
Perhaps some term needs to be coined, referring to the magic of valves when used to produce neutral sound, as opposed to the so called 'valve sound', a term often used to refer to sound that is anything but neutral, frequently resulting from using nonlinear valves at nonideal operating points with substandard output trannies.
How about 'valve fidelity' ?
Anyway, as to the Electrocompaniet amplifiers, I was not referring to the soundstage, but rather the tonal balance and midrange lucidity.
And, no, I am not one of their proponents, just stating what I've seen people say about them in the hifi press. For the price, they deliver sensible goods, but I think the tonal balance of their entry level amplifiers is a bit too much off, and the sound stage becomes a bit too onedimensional for my taste. Can't exactly call them bad, though, considering the price. I have no experience with their high end products, though, so I cannot contribute any opinions of my own there.
Certainly, the EC1 is not a contender for the high end. However, I hear the Nemo (600W monoblock) is one of the most neutral power stages around. Stereophile, as usual, gave it rather high praise.
The CD player seemed nice, though, last time I listened to it.
On a side note, the Nemo was originally prototyped under the name 'Enigma', in possibly the coolest enclosure I've ever seen. It was a cube in clear aluminum, with the top having the raised, crisscrossing grooves you typically see used for traction on industrial stairs or trucks. And there was a sunken-in, rounded triangle on the front, ending in black acrylic with the characteristic 'E' on it. Weighed a bunch, generated tons of heat, and output a kilowatt or so with high bias.
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