I did say before it depends on how many pre magnetisation is used. For instance, if the pre magnetisation is only 0,5T 80mA will give more headroom instead of less. So you need to have the design criteria before saying it. But probably you are right for the xe-20 (but not know for sure unless you did measurements). So please add some measurements here.
SE have weak bass compared to PP amplifiers and solidstate, it's just a fact. We can only make the best out of it. I love the work Tango did but it dosn't mean it can not be improved.
One of the reasons i made this transformer is because somebody wanted this improvement. And he dos use a 300B.....
SE have weak bass compared to PP amplifiers and solidstate, it's just a fact. We can only make the best out of it. I love the work Tango did but it dosn't mean it can not be improved.
One of the reasons i made this transformer is because somebody wanted this improvement. And he dos use a 300B.....
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The large HiB double c-core* dos just a part of the job. Special winding techniques, yes and no.
I not use standard layer technique, but all techniques i use you can find in books written long time ago. So nothing new only combining them the right way.
*I used a 800W/50Hz core ( he he and just 30W/18Hz, can you imagine....?)
I not use standard layer technique, but all techniques i use you can find in books written long time ago. So nothing new only combining them the right way.
*I used a 800W/50Hz core ( he he and just 30W/18Hz, can you imagine....?)
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The distortion of the transformer will depend on the TOTAL B and the inductance. If your TOTAL B for a given Pout is higher you will get more distortion. Very simple. That amp can only mange 6.5W with 4% THD @ 1KHz running the 300B at 350V/78 mA. You don't need to do this. If you have a good 300B you can get less THD at all frequencies with only 350V/60 mA. At low frequency the difference will even more because the XE20 will perform a lot better than at 78 mA.
This is another story. If you think that you can improve why don't you do it? It is not just performance you have to sell them!!
Tango would make custom designs as well. You cannot compare a high quality standard product and a custom one. They are made with different criteria which doesn't mean that the standard is not good....
You changing the the subject a little bit. First you talk about headroom, now you talking about distortion. Stay to the subject please.
I already improved it, you can see the measurements i did so far. For me selling is not so important.
Maybe Tango did made costum made transformers but i found not many information about this, it is not interesting information for me. They could start with a higher standard them self for a start.
I already improved it, you can see the measurements i did so far. For me selling is not so important.
Maybe Tango did made costum made transformers but i found not many information about this, it is not interesting information for me. They could start with a higher standard them self for a start.
Not at all. The fact that people do not specify distortion levels doesn't mean it is a good way. If you say you have 30W at 18Hz but the it is working at 2T and distortion is 15-20% do you find it reasonable? I don't.
The transformer I use for a 300B made on 40x50 core is specified as 13W at 30Hz @ 0.75T and with 26H minimum inductance (i.e. for just 1 mW output!!). For 3 mW output the inductance is 33H! This will guarantee a low distortion level, overall not so different to that at 1KHz. If I used more induction the headroom would be quite a bit higher but the distortion? Not really hifi....
Then you cannot make that sort of comparison...
Tango has closed down. They will not make transformers anymore....for now. Business is not DIY.
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No i have not all details.
Winding loss (=copper loss) i already told, 0,14dB
For inductance is not a standard measuring methode, it depends from signal strength and frequency, better look at the frequency response (preferable 1Hz- 1MHz or even wider) a transformer has at low power and the saturation at a given frequency. Better would be the frequency response at low/mid/high power.
The same is for leakage and capacity: look at the frequency response.
Square waves tell you if there is a resonance problem.
Winding loss (=copper loss) i already told, 0,14dB
For inductance is not a standard measuring methode, it depends from signal strength and frequency, better look at the frequency response (preferable 1Hz- 1MHz or even wider) a transformer has at low power and the saturation at a given frequency. Better would be the frequency response at low/mid/high power.
The same is for leakage and capacity: look at the frequency response.
Square waves tell you if there is a resonance problem.
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Nothing for freeYou need more windings so copper loss is higher and winding capacity too.
What is the copper loss of your transformer and frequency response?
It's easy for me to get 13W/30Hz/0,75T (ac+dc) with my transformer by changing the air gap.
Yes and you need to look at the current too. That is optimized to work at 75-85 mA. More than 85 mA are not necessary with 300B for 10-14W Pout. The Bdc is about 500G higher than Bac at 13W.
The power loss is 0.3 dB and equally shared by primary and secondary. Actually the secondary has slightly lower DC resistance to compensate for the fact that the Rac will be a bit higher because of the larger wire. The bandwidth (-3 dB) is 3Hz-67KHz...with no peaks and deeps. Pretty good for E+I which hasn't got a square core and using normal materials.
I know it is easy once one knows how to do it...if the winding is properly made.
It will be less appealing to some because if one says it is 40W at 30Hz (but it is close to saturation) makes it look big and 13W @ 0.75 T small!
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For signal transformers, I think measuring the inductance for just 10 Gauss AC induction (often referred as minimum inductance) at 50Hz is pretty standard. Knowing the minimum AC induction you figure out the AC signal you need to apply.
Nothing for free
The dominant capacity at the first resonance is that at the interfaces between primaries and secondaries. Increasing the windings to keep leakage inductance low will make the capacity higher. However one can redistribute the capacitance to get it back at lower values by horizontal sectioning. The merit factor for a smooth frequency response is of course important but here the source impendace has to known to optimize in the best possible way. If this is not known one has to figure out a limited range of source impendances where it will work fine.
retification
Oeps, wrong data here!!!!
I looked at the wrong data, its a 500W core, not a 800W, damn.
I was looking in another datasheet i have and looked one row to low.... (calculations are right)
Oeps, wrong data here!!!!
I looked at the wrong data, its a 500W core, not a 800W, damn.
I was looking in another datasheet i have and looked one row to low.... (calculations are right)
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EI would never be my first choice. Distortion is unnecessarily high. Probably the distortion of your EI is higher then a smaller c-core, specially if the c-core has a HiB core.
It's strange to me that you have 33H and only 13W / 30Hz / 0,75T. I think a 16-17Hz should be more realistic. You have a much bigger transformer then i do.
It's strange to me that you have 33H and only 13W / 30Hz / 0,75T. I think a 16-17Hz should be more realistic. You have a much bigger transformer then i do.
It's aboslutely not true. As long as the induction is within limits, properly calculated and inductance high enough there is no high distortion. The C core has an advantage because it can work at higher B and so one can save in size or get a bit better power loss figure and/or inductance for the same size but that's it. Also one might (because the design is the most important thing and the core alone gives no guarantee) get a little better HF frequency response but overall nothing like the difference between night and day.
I don't know how do you get those figures. I have measured it on the finished amplifier. -3 dB is at 3Hz for 2.83V RMS at the secondary.
33H is the design value for the minimum inductance (3 mW output).
It was acceptable for the owner. The Pmax, at the usual 5% THD, of that amp was over 13W @ 1KHz. I don't remember the exact figuers at lower and higher frequency but thery were pretty the same, not more than 0.5% increase. I have them somewhere and will post them when I get back to Italy if you want. If you look at what you need for a DHT SE in this power range it can be acceptable. C core could be smaller but it is not really a drama.....
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To be more precise that is a consequence of the gap choice. Instead of picking a gap size for general use I optimized for a max DC of about 95 mA. This way you can use a smaller gap and the permebility (and thus inductance) will be higher.....
If the 300B in that amplifier will never work at more than 85 mA it is more than enough. There is no reason to gap it for 120-130 mA or whatever...
As you can see this is one of the different criteria between standard products that have to work in a number of applications and a custom specific product!
To my knowledge a good M6 0.3 mm has about 1W/Kg loss guaranteed at 50 Hz @1.7 T. Figures increase slightly only for very small cores. It's not difficult to find.
Have a look at the Thomas & Skinner catalouge, for example. They also have 3 different M6 grades selected for permeability and M4 0.23 mm.
Are your figures referred to higher frequency? In that case is not really a problem. One might not want too much core influence on the sound at medium to high frequencies.....
Have a look at the Thomas & Skinner catalouge, for example. They also have 3 different M6 grades selected for permeability and M4 0.23 mm.
Are your figures referred to higher frequency? In that case is not really a problem. One might not want too much core influence on the sound at medium to high frequencies.....
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