From what I can gather, Hashimoto, James and O'Netics are the top OPTs. There has been a lot of praise for the O'Netic's Level III iron from a number of top designers and, if you're willing to pull out all the stops, there's also the O'Netic's Level V (they are more expensive).
The OP also asked about which "affordable" transformer is good and it seems that the Edcors aren't too dear, considering the quality.
Best Regards,
TerryO
The OP also asked about which "affordable" transformer is good and it seems that the Edcors aren't too dear, considering the quality.
Best Regards,
TerryO
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Is Bud still offering Lv4 & 5? The GM70 OPT mentioned are Lv3. I love them. Also a pair of Lv1, but I've not compared them yet.
I have to say that your source better be really good to fully appreciate the differences of these transformers. 24bit DAC or vinyl, weakest link of the chain bla bla bla...
Greenvalve,
When you start talking about this level of effort and expense, I can't imagine anyone (other that a certain Scandinavian "Squarehead") that wouldn't pair this quality of gear with an appropriate source as well.
Last Thursday evening, Bud and I gave a presentation at the Pacific Northwest Audio Society. I wasn't Boo'd (or lynched) and Bud was given an Ovation, so it was an entirely gradifying evening.
Bud also handed me a couple of Level 3 OPT to take to another friend of ours, that will be replacing some Edcors in his new amp. He wants to try both to see what the differences may be. I also have a project (or two) that, once it gets to the final stage, will be getting some Level 3 transformers as well.
Best Regards,
TerryO
I'm using a pair of [FONT=Arial, Arial, Helvetica]H-20-3.5U transformers in a Loftin-White circuit. I've also tried it in a JE Lab circuit with similar results. The highs and midrange were very good, but the bass is a little wooly. To my ears it sounds very similar to the James [/FONT]JS-6123H[FONT=Arial, Arial, Helvetica]. I don't have experience with their more expensive transformers, but I find most winders have a similar "house" sound.
I built a drd about 8 years ago with some excellent iron from Electra-Print. It's my favorite to date. The sound is very neutral and the bass is the best i've heard in this circuit. Not sure if Jack is willing to resurrect his older transformer design, but it may be worth the price if you're considering a drd.
[/FONT]
Plitron toroid, if I'm building one of tho$e amp.
otherwise, an over-rated Hammond or a one-electron will do.
Edcor, or cheap Hammond, I use to develop the design, then do one of the above usually.
If I do something like a one-off design: American Transformer, UTC , or even Triad, adjusting for taste. I'll even use a RCA Radiola transformer if they like it better.
otherwise, an over-rated Hammond or a one-electron will do.
Edcor, or cheap Hammond, I use to develop the design, then do one of the above usually.
If I do something like a one-off design: American Transformer, UTC , or even Triad, adjusting for taste. I'll even use a RCA Radiola transformer if they like it better.
I use 60W toroids of my own design, but in PP, not SE amplifier. I don't think fixed air gap toroid is really optimal solution for SE. Double C core is much easier to construct with air gap of desired thickness.
I'm thinking Plitrons for my 300B amps. Any reason not to do it besides the cost? where is the most bang for the buck in the high end stuff?
Dave C2, DavesNotHere and Audiofanatic I am glad to see you like Plitrons. I just purchased Menno Vanderveen's books in the hopes that I could learn enough to design a Single Ended built around the KR 300bxls and all toroid transformers (meaning all Plitron power, output and choke). If you would like to share info please feel free to contact me here. I have spoken with some folks at Plitron and have found them helpful even introducing me to Mr Vanderveen, who I have not spoken with yet as I am waiting to finish my reading.
I'm just reviving this thread to see if there are any new views on the best SE OPT for a 300b amp. It's a very common amp, and it would be good to optimise the OPTs we use.
I've rebuilt my amps with a much better circuit - 4P1L in filament bias> LL1620/18mA > 4P1L in filament bias> Hammond 126C > 300b. So far I've compared Lundahl LL1660/80ma and Audio Note Trans 152. The AN is huge and has slightly better dynamics and bass. The Lundahl is slightly better (I think but not 100% sure) on vocals. I previously preferred the O-netics level 1 "commercial" 3.3K model to both, and am rebuilding this with the same circuit. Will post the results.
Meantime - any revised suggestions for a great sounding SE OPT?
Andy
I've rebuilt my amps with a much better circuit - 4P1L in filament bias> LL1620/18mA > 4P1L in filament bias> Hammond 126C > 300b. So far I've compared Lundahl LL1660/80ma and Audio Note Trans 152. The AN is huge and has slightly better dynamics and bass. The Lundahl is slightly better (I think but not 100% sure) on vocals. I previously preferred the O-netics level 1 "commercial" 3.3K model to both, and am rebuilding this with the same circuit. Will post the results.
Meantime - any revised suggestions for a great sounding SE OPT?
Andy
Amplimo Toroid (design Menno van der Veen) transformers, the best there is. I am definitely not saying this because I have a pair for sale for 60% of newprice. The same as Plitron I believe. Single Ended uitgangs trafo's
http://www.amplimo.nl/images/downloads/ds vdv/vdv3035.pdf
This has "saturation primary current 172mA". That seems pretty high for a quoted 28H primary inductance. Any idea of the comfortable working current? It's not too clear.
Which ones do you have and how were you running them? What did they sound like?
andy
This has "saturation primary current 172mA". That seems pretty high for a quoted 28H primary inductance. Any idea of the comfortable working current? It's not too clear.
Which ones do you have and how were you running them? What did they sound like?
andy
Hi Andy
These talk the talk, but do they walk the walk?-
http://www.monolithmagnetics.com/images/stories/datasheet_S-9.pdf
http://www.monolithmagnetics.com/index.php?option=com_content&view=article&id=62&Itemid=60
Double C cores with impressive specs, but I've been unable to find any independent reports on them. Can anyone help?
I'm still using some old Audio Note "Spec B" 2k5 transformers than came with a Kit 1 in 1995! The only parts, other than the chassis I'm still using.... I think these are now the 152 types you mentioned.
I've considered Sowter's SA08- Rod Coleman uses them- and also could probably still get hold of the ones used in the Border Patrol amps (I use Border Patrol interstage transformers). But the Monoliths offer double C-cores at not much higher cost- tempting, in theory. I'm also keen to move to a 3k3 or 3k5 primary- the ANs' are 2k5, which Rod reckons increases distortion unacceptably
Thanks
Paul N
These talk the talk, but do they walk the walk?-
http://www.monolithmagnetics.com/images/stories/datasheet_S-9.pdf
http://www.monolithmagnetics.com/index.php?option=com_content&view=article&id=62&Itemid=60
Double C cores with impressive specs, but I've been unable to find any independent reports on them. Can anyone help?
I'm still using some old Audio Note "Spec B" 2k5 transformers than came with a Kit 1 in 1995! The only parts, other than the chassis I'm still using.... I think these are now the 152 types you mentioned.
I've considered Sowter's SA08- Rod Coleman uses them- and also could probably still get hold of the ones used in the Border Patrol amps (I use Border Patrol interstage transformers). But the Monoliths offer double C-cores at not much higher cost- tempting, in theory. I'm also keen to move to a 3k3 or 3k5 primary- the ANs' are 2k5, which Rod reckons increases distortion unacceptably
Thanks
Paul N
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Hi Paul,
Yep - 2.5K isn't ideal. I've wondered about using the ANs on the 4 ohm tap. Must try it. If you look at all the distortion evidence, the best primary seems to be 5k or even more. I have a whole chart of distortion values from this guy:
"For the 300B: The minimum actually occurs at 6.5K in one case and 10K in the other (because of the different operating points). The DCR = 0.1*RL. Adjusting the DCR has the same effect as adjusting the reflected load. Something I am contemplating: Is it better to compensate the transformer's IR drops to get the desired loaded voltage gain or to compensate the transformer for the desired impedance ratio. Note: . I have a hunch it may be better to be a bit on the high impedance side of the 3HD minimum. It seems that so that as the tube varies or the load varies, the 3HD doesn't seem to change as much being on the high side. (7K +/- 3.5K) AND most 8 ohm speakers are less than 8 ohms.
Very interesting. This effect is going 3 or 4 different directions at once... For the last investigation, I didn't publish the primary DCR used... I used a DCR formula of DCR = .1*RL, where RL is the reflected load. Repeating the last post:
300 volts,-54.3grid, 60 mils, 3500 ohms, 3.3 watts, -31/-51.5db
350 volts,-70.8grid, 50 mils, 5000 ohms, 4.3 watts, -30.1/-47.8db
The DCR was 350 and 500 ohms.
And in the last post, for the minima for 3rd I had:
300 volts,-54.3grid, 60 mils, 7000 ohms, 2.22 watts, -36.7/-88.9db
350 volts,-70.8grid, 50 mils,11000 ohms, 2.56 watts, -37.3/-93.8db
The DCR was 700 and 1100 ohms.
So...tried varying DCR. This time used DCR = .05*RL to see how this would effect the 3rd order minima. I used the same op points from Mike L (as before) but just changed DCR on the transformer. Then varied the RL until I hit the 3rd order minima. The results were interesting... The 3rd order minima doesn't occur until much higher effective loads. It moves way up by lowering DCR in both cases:
300 volts,-54.3grid, 60 mils,12000 ohms, 1.45 watts, -43.7/-87.3db
350 volts,-70.8grid, 50 mils,25000 ohms, 1.27 watts, -48.4/-104 db
The DCR was 600 and 1250 ohms.
So it looks like DCR actually helps us get a good 3rd order minima. Looking at the 11,000 ohm load case on the 300B with the 350v operating point, and a 1100 ohm DCR...the 3rd order minima was -93.8 db. With a 550 ohm DCR (half) and 11,000 ohm load... the 3rd order minima is only -64.8 db. So it is better by 29 db by doubling the DCR. Dave, and Mike, thanks for finding something very interesting. I meant to say in the conclusion that raising DCR helped to get a better (deeper) 3rd harmonic minima at a lower load. One thing that lowering DCR *may* do is that it may cause a deeper Null in the 3rd harmonic minima. So if you aren't concerned with power, a lower DCR *may* get less 3rd order distortion *if* you have RLoad at the minima." Mike
Can't remember who "Mike" was.
Yep - 2.5K isn't ideal. I've wondered about using the ANs on the 4 ohm tap. Must try it. If you look at all the distortion evidence, the best primary seems to be 5k or even more. I have a whole chart of distortion values from this guy:
"For the 300B: The minimum actually occurs at 6.5K in one case and 10K in the other (because of the different operating points). The DCR = 0.1*RL. Adjusting the DCR has the same effect as adjusting the reflected load. Something I am contemplating: Is it better to compensate the transformer's IR drops to get the desired loaded voltage gain or to compensate the transformer for the desired impedance ratio. Note: . I have a hunch it may be better to be a bit on the high impedance side of the 3HD minimum. It seems that so that as the tube varies or the load varies, the 3HD doesn't seem to change as much being on the high side. (7K +/- 3.5K) AND most 8 ohm speakers are less than 8 ohms.
Very interesting. This effect is going 3 or 4 different directions at once... For the last investigation, I didn't publish the primary DCR used... I used a DCR formula of DCR = .1*RL, where RL is the reflected load. Repeating the last post:
300 volts,-54.3grid, 60 mils, 3500 ohms, 3.3 watts, -31/-51.5db
350 volts,-70.8grid, 50 mils, 5000 ohms, 4.3 watts, -30.1/-47.8db
The DCR was 350 and 500 ohms.
And in the last post, for the minima for 3rd I had:
300 volts,-54.3grid, 60 mils, 7000 ohms, 2.22 watts, -36.7/-88.9db
350 volts,-70.8grid, 50 mils,11000 ohms, 2.56 watts, -37.3/-93.8db
The DCR was 700 and 1100 ohms.
So...tried varying DCR. This time used DCR = .05*RL to see how this would effect the 3rd order minima. I used the same op points from Mike L (as before) but just changed DCR on the transformer. Then varied the RL until I hit the 3rd order minima. The results were interesting... The 3rd order minima doesn't occur until much higher effective loads. It moves way up by lowering DCR in both cases:
300 volts,-54.3grid, 60 mils,12000 ohms, 1.45 watts, -43.7/-87.3db
350 volts,-70.8grid, 50 mils,25000 ohms, 1.27 watts, -48.4/-104 db
The DCR was 600 and 1250 ohms.
So it looks like DCR actually helps us get a good 3rd order minima. Looking at the 11,000 ohm load case on the 300B with the 350v operating point, and a 1100 ohm DCR...the 3rd order minima was -93.8 db. With a 550 ohm DCR (half) and 11,000 ohm load... the 3rd order minima is only -64.8 db. So it is better by 29 db by doubling the DCR. Dave, and Mike, thanks for finding something very interesting. I meant to say in the conclusion that raising DCR helped to get a better (deeper) 3rd harmonic minima at a lower load. One thing that lowering DCR *may* do is that it may cause a deeper Null in the 3rd harmonic minima. So if you aren't concerned with power, a lower DCR *may* get less 3rd order distortion *if* you have RLoad at the minima." Mike
Can't remember who "Mike" was.
Sounds like prose from Mike LaFevre of Magnequest.
Magnequest iron was quite good, I'm not sure what is going on with MQ these days, but I recently tried to find a source for his plate chokes and was unable to do so.
I've used a small number of Electra-Print custom built output transformers in SE amp projects - without exception they've been excellent.
I also like the old Tamura F-5002 with the 300B, these apparently are no longer made, and when they were the price was pretty stratospheric - the most expensive OPTs I've ever purchased.
I was the maker of the KTA 3030 amp referenced early in the thread.. Ancient history..
Magnequest iron was quite good, I'm not sure what is going on with MQ these days, but I recently tried to find a source for his plate chokes and was unable to do so.
I've used a small number of Electra-Print custom built output transformers in SE amp projects - without exception they've been excellent.
I also like the old Tamura F-5002 with the 300B, these apparently are no longer made, and when they were the price was pretty stratospheric - the most expensive OPTs I've ever purchased.
I was the maker of the KTA 3030 amp referenced early in the thread.. Ancient history..
I have both the 3K5 and 2K5 versions. They are super soundwise. I used them with 80 or 85 mA if I remember well.
Choose a Transformer in Audio
This mentions Daburu which I've been trying to track down. They seem to have gone up in price a lot. DA-50X is already over 400 euros. I'm assuming this is 5K.
LOOK-AUDIO MATERIEL AUDIOPHILE - Mentions Daburu and some cheaper "45" ones.
Transfo Daburu DA-35x vs LL1664 : Electroniques - Cinetson - Hifi et Homecinema Bit of discussion here including the great quote "crois moi camarade les Chinois ont encore beaucoup de chemin a faire avant d 'égaler les transfos de sortie Chrétien que celà te plaises ou non."
Here's another thread:
http://www.diyaudio.com/forums/tubes-valves/116499-chinese-output-transformer-300b-set.html
This mentions Daburu which I've been trying to track down. They seem to have gone up in price a lot. DA-50X is already over 400 euros. I'm assuming this is 5K.
LOOK-AUDIO MATERIEL AUDIOPHILE - Mentions Daburu and some cheaper "45" ones.
Transfo Daburu DA-35x vs LL1664 : Electroniques - Cinetson - Hifi et Homecinema Bit of discussion here including the great quote "crois moi camarade les Chinois ont encore beaucoup de chemin a faire avant d 'égaler les transfos de sortie Chrétien que celà te plaises ou non."
Here's another thread:
http://www.diyaudio.com/forums/tubes-valves/116499-chinese-output-transformer-300b-set.html
I svapped my Audio Note OPTs for a Daburu 3.5k... That was el cheapo AN - IE core I think.
The Daburu is better in every aspect and with great margin also. The amp is in fact en AN kit1 (heavily modified)
Great OPTs...
"Nano-crystal Double-C core output transformer 3.5k:4/8/16ohm Single Ended"
The Daburu is better in every aspect and with great margin also. The amp is in fact en AN kit1 (heavily modified)
Great OPTs...
"Nano-crystal Double-C core output transformer 3.5k:4/8/16ohm Single Ended"
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