The original also has a 4 ohms tap but that is not really necessary. And of course the core must have an air gap because it carries the 1A DC bias.
jd
I want to perform experiments with output transformers instead of current sources and I want to have an universal output transformer for single ended solid state output.
Which exactly parameters must I have to submit to the manufacturer of single ended output transformers, if I know only the load resistance (e. g. 8 Ohms) and the wanted output power (e. g. 10W) respective the wanted output current (e. g. 3A)? I am not familiar with the parameters to core permeability and air gap.
And an additional question: If I haven't p-spice model for the transformer, what value I must choice for the replaced resistor in the drain line (I would say accordingly the winding ratio, but I am not shure)?
Thank you very much for advices
Wow 3A, I don't think that is possible.
Maybe you should try parafeed? I.e. just use a toroidal transformer (or custom parafeed tranformer (no airgap))as OT with a dc blocking cap. You could use a Lundahl LL1694 (3A) 40mH or the new LL2733 (3.4A) 100mH as current source.
Because I don't think a single ended output transformer that can withstand 3A of dc would work very well across the frequency range.
3A should be not a definite condition, but only one example. Maybe it is better to build a SE amp with 200V Vdd, choosing a smaller idle current but a greater winding ratio.
Currently I am talking only about fundamental considerations and the basic parameters, that I need for ordering customized edition of such transformer
By the way, this commercial single ended amp uses output transformer - the only, about I know:
http://www.envogue-24.de/Neue Seiten/ear/M100A.html
http://hometheaterreview.com/ear-paravicini-m100a312-tube-amp-reviewed/
Last edited:
I intend to run my output mosfet at around 100- 150 mA, within the ratings of the specified transformer (One Electron UBT-1). I'll be blowing about 30W per device at that current level and 200-250V drain voltage. This is most likely not within the sweetest spot of the output fet, but I'm not really all that concerned, as the output device will be inside a feedback loop and have some little brothers ahead of it to help straighten it out. This will not be a minimalist amp without global feedback like the one Nelson ginned up, but still one pretty much in line with tube methodology. It would be amusing to slap together a tube front end to drive the mosfet as well. I may do that as a side project after I finish the solid state version. Remember, Nelson designed his amp to be as simple as possible to encourage people to get off their backsides and build something. The concept I've outlined is something I want to uinvestigate for myself. A big depletion mode fet should have as many uses as a cat's got hair...
BTW - thanks to the guys who rooted out the Nemesis schematic (what concept/competing amp Hiraga had in mind when he named the amp, I'd like to know). It's an interesting concept, but not what I have in mind, especially as I'm determined to use the iron I have on hand.
BTW - thanks to the guys who rooted out the Nemesis schematic (what concept/competing amp Hiraga had in mind when he named the amp, I'd like to know). It's an interesting concept, but not what I have in mind, especially as I'm determined to use the iron I have on hand.
OK, this is how far I got on the Nemesis transformer.
I spoke with Per Lundahl and he can do one, based on the LL2410 I believe, but modified with a air gap for the DC bias. Projected price euro 160 each.
Then I got in contact with Jack Elliano of Electraprint Audio. He can do one for about $ 75, and he is willing to sell me a prototype which can be tested and then if necessary to be returned to him for final design. However, the shipping to my home in Holland is $ 50 each way, so I may end up with $ 100 in shipping for a $ 75 xformer. Since I have a perfectly working Nemesis with the original xformers, I think I'll pass for the new xformers.
I suggest that someone in the US will take this on, the shipping will be (much) less, but he/she must be able to measure the xformer as to freq response, undistorted power and preferably distortion versus frequency. Anybody game?
jd
I spoke with Per Lundahl and he can do one, based on the LL2410 I believe, but modified with a air gap for the DC bias. Projected price euro 160 each.
Then I got in contact with Jack Elliano of Electraprint Audio. He can do one for about $ 75, and he is willing to sell me a prototype which can be tested and then if necessary to be returned to him for final design. However, the shipping to my home in Holland is $ 50 each way, so I may end up with $ 100 in shipping for a $ 75 xformer. Since I have a perfectly working Nemesis with the original xformers, I think I'll pass for the new xformers.
I suggest that someone in the US will take this on, the shipping will be (much) less, but he/she must be able to measure the xformer as to freq response, undistorted power and preferably distortion versus frequency. Anybody game?
jd
I'm about to start mucking around with using SE (and PP) OPTs as inductors.
This has the advantage that a small inductor in series with the main inductor will deal with the parallel C issue.
The downside with this is the DC offset due to winding R. But the numbers look pretty much the same as as running DC (or PP DC) on the primary of a normal or garden type tube OPT.
IE. If you have an SE OPT, it can handle a certain N x I without saturating. It frankly doesn't care whether that is applied at the primary or the secondary.
BTW This transformer is sized for 1.3A DC bias so it is perfect for the IXYS SE amp as discussed here. Pout about 12W with 40-45VDC supply.
jd
Now would not be a good time for me to commit to more projects 
It does sound like fun though.
However, I happen to have 2 Hammond 195T5, 100mH, 5A, 0.64 ohm Chokes. Naturally these are for powerline freqs but what would be expected of them as a choke load in a configuration like the Delite. Possibly for the upper ranges since 100mH probably would not cut it in the bass region? I'm concerned the laminated core will contribute to much of it's own nonlinearity 
It does sound like fun though. However, I happen to have 2 Hammond 195T5, 100mH, 5A, 0.64 ohm Chokes. Naturally these are for powerline freqs but
what would be expected of them as a choke load in a configuration like the Delite. Possibly for the upper ranges since 100mH probably would not cut it in the bass region? I'm concerned the laminated core will contribute to much of it's own nonlinearity
good advice and good idea.
here another source: about the URL
EXPERIENCE electronics - Home
I see datasheet of this transformer:
http://www.experience-electronics.de/englisch/Datenbl%E4tter/DBEA265.pdf
Unfortunately it was be optimized for the single ended tube output (high voltages) about
EXPERIENCE electronics - Monoblock Single Ended 30 W
But this company makes also custom specific versions.
What I would like to know is whether anybody is interested in pursuing this further. I just did this research because many here said they would be interested. That's OK, but if there is no real interest, I will cancel this project end of next week.
jd
janneman ......
frankly - I'm interested in that same as in zillion other things ;
really interested , but always short in time ;
I have handy some old 100W 100V line xformers ..... and I'm curious can I try them .... maybe as parafeed for starters ....
anyway ......... as I said - I'm short in time , so - feel free to be the same regarding that project .
sit down and enjoy in music .... electronic isn't so much important
frankly - I'm interested in that same as in zillion other things ;
really interested , but always short in time ;
I have handy some old 100W 100V line xformers ..... and I'm curious can I try them .... maybe as parafeed for starters ....
anyway ......... as I said - I'm short in time , so - feel free to be the same regarding that project .
sit down and enjoy in music .... electronic isn't so much important
janneman ......
frankly - I'm interested in that same as in zillion other things ;
really interested , but always short in time ;
I have handy some old 100W 100V line xformers ..... and I'm curious can I try them .... maybe as parafeed for starters ....
anyway ......... as I said - I'm short in time , so - feel free to be the same regarding that project .
sit down and enjoy in music .... electronic isn't so much important
Yes I know the feeling, so many projects, only 24hrs in a day
Have fun,
jd
Another way to get rid of DC... Aleph work-alike on the flip side.
http://www.diyaudio.com/forums/tubes-valves/151220-spud-schade-pp-anti-triode-ecl86.html
Not to mention plate to plate (or drain to drain) Triode emulation.
http://www.diyaudio.com/forums/tubes-valves/151220-spud-schade-pp-anti-triode-ecl86.html
Not to mention plate to plate (or drain to drain) Triode emulation.
100W 8ohm => 3.5A
You could SE them with about 1A of bias. Bass will be lacking.
Or PP, use a mic trans to split the input, B+ on 4ohm tap and FETs on 16 ohm and common. Maybe call the CT earth, and supply the FETs B-. B- of 12V and 1A or so each side would suit a bunch of devices.
A couple of bias resistors and you're done. Quick and dirty
I just had a nice talk with Jack Elliano at Electro-Print, and we
are putting something into motion.
Great! Looking forward to what you will come up with!
I'll close my loop to Jack.
jd
tnx for thoughts ;
I forgot to say that these are matching xformers - between SS amp output and 100V line , so primary is pretty low ohmish , and sec is high ohmish ....
interesting - I never measured winding ratio
..... another thing to do ......
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.