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Gday inmates I though I would let you guys know I received my trans this week.
They are massive easily the biggest trans I own. I think I waited about 8 maybe 9 months all up. I have lost count to be honest.But if they are as good as they should be being finemet core and all. They really would be a audio bargain. And waiting 9 months would be easily worth it. What wasn't worth it was not knowing if I would ever get them. I had almost given up hope so I thought I better let you guys know encase there is other poor ba###ds out there wondering the same. This might help with similar doubts.
Why they take so long my thinks
1 manic depressive genius that cant accept anything but perfection that only works when he can feel it. I can relate to that. But more likely-
2 makes so many trans he just cant make enough
3 gets them made by children in india
4 sadist that enjoys people begging him.
5 He just doesn't like me.
er that's all I can think off.
Finally they are a great deal. Easily 1/4 of the price any other similar trans can be bought for. Maybe he was doing me a favour I don't know his current prices.
I haven't opened them yet. I am considering scalping them on fleabay for 2khow much are a pair of instant tribute finemet gm70 trans worth? ;)What's 9 months of mental anguish worth? I don't want to think about that.
2k would almost buy a pair of Siemens L405 that I have wanted for ten years. hang on its fleabay. I will put 10k on them.And only include one when I send them out.
Edits: 07/28/14 07/28/14Follow Ups:
It's a pitty that you don't give any details about this transformer.
You say heavy but not give the weight.
65H at 120mA but not how much power can be handled (at 20Hz)
what is the dc Rp and dc Rsec?
I saw finemet transformers with heavy copperloss, less then 88% transfer (0,55dB loss). A very good transformer dos > 95% (0,21dB)
Be aware that using finemet usually give poor results for: copperloss, low & high frequency response, powerhandling.
It's a pitty that you don't give any details about this transformer.
You say heavy but not give the weight.
65H at 120mA but not how much power can be handled (at 20Hz)
what is the dc Rp and dc Rsec?
I saw finemet transformers with heavy copperloss, less then 88% transfer. A good transformer dos > 94% (0,26dB)
> I saw finemet transformers with heavy copperloss,
> less then 88% transfer. A good transformer dos > 94% (0,26dB)
Finemet have only Bmax <= 1.25T, so in any case it will require a lot of primary turns. I see nothing wrong with efficiency 88%, copper loss is linear, it doesn't degrade sound quality, just very small drop of max power.
Well, if you are right about that you should buy the smallest transformer available. You save a lot of money. Maybe a loss of 50% would be good or even more loss?I tryed a Lundahl 1664 (300b, 3k/8Ohm) with some friends and this is a remarkable nice little transformer. Excellent frequency response, very good square waves. The only think what isn't good is the copperloss.
This transformer sounds very well to but the sound you get from a really good transformer (same frequency response, square wave behavior but lower copperloss) is much better. Bigger soundstage, space, more open, more dynamic etc.Having high copperlosses means normally that a lot of windings is used, that means more windingcapacity and that isn't good for the high frequecy response.
Finemet is very useble for smaller transformers where windingcapacity is of less concern. Then it is even possible to have low coreloss and low copperloss at the same time.
Making a good se gm70 transformer with finemet looks more snake oil to me.
Edits: 05/10/15
> Having high copperlosses means normally that a lot of windings
> is used, that means more windingcapacity and that isn't good
> for the high frequency response.
Not necessary, it may mean that wire used for primary and / or secondary is relatively thin, e.g.
0.35 - 0.4mm for primary
0.7mm for secondary (in several sections parallel)
Its OK to have slightly higher copper losses and lower leakage inductance.
Difference between 88% and 94% efficiency can be compensated with volume pot if necessary.
Compensating volumeloss is easy but we are talking here about sound character. If you like a more dull sound go for the higher copper loss.
If copperloss was not importand why do you think every quality brand uses bigger cores instead of using more windings? Are they insane?
To make even a workable output transformer for the gm70 you have to use very large core, more then 20^cm, a total weight of more then 10kg each.
I guess a high frequency limit of 30k-35kHz -3dB is not what people are looking for.
> If copperloss was not importand why do you think every quality
> brand uses bigger cores instead of using more windings? Are they insane?
Bigger core allows to reduce primary turns.
BTW, copper loss depends upon not only number of turns, but also on wire diameter. Reducing wire diameter to get nice fit on bobbin and lower leakage inductance is OK, I see no problems there.
Take basic formulas of transformer design, you will see by yourself how primary inductance, core size, number of turns, wire diameter, sectioning, parasitic parameters, etc. relate to each other. Right now you pick up copper loss alone as quality factor yet omit other parameters.
I am sorry to say but did you ever wind a transformer?
You try to find excuses for everything and you not actually something of any importance.
> I am sorry to say but did you ever wind a transformer?I did, including PP toroids.
> You try to find excuses for everything and you not actually
> something of any importance.Its not an excuse, just a theory. Saying that transformer with efficiency 88% is much worse then one with 94% doesn't make sense unless other parameters like Bmax, leakage inductance, stray capacitance and resonant frequency are taken into account.
Edits: 05/10/15
It looks rather strange to me that you did because from several answers i understand you not understand the problem of finemet and large tubes as a gm70.
For a given number of turns you can not increse the wire diameter unless you made some wrong calculations before ( filling factor, insulation thickness)
The idea that 3,5 kg came up your mind is..... .
An audio transformer needs to transfer as much power as possible and have the best possible frequency response. Coreloss or copperloss need to be avoided. Copperloss is equal all over the frequency range but coreloss not. At medium (100Hz and more) to higher frequencies the magnetic field is (super) small so the core loss is small to.
So at medium and high frequencies the coil dos the job and not the core, you can even remove the core if you wanted to.
For an given size transformer core you need 50% more windings if you use finemet instead of HiB silicium.
Take that into your theory about leagage induction and winding capacity....
I met Pieter in May at the high end audio show in Munich. He is a very nice person and a one-man operation with good demand for his product, hence the lead-time for his transformers.
I would keep and use your GM70 transformers as originally intended.
Sorry for the delay I just opened them! They are like animater or something. They are so heavy it takes too hands to lift them far enough to get your finger beneath them. The sticker says they are 65H @ 120 ma. I never expected to get that sort of inductance.
I am not sure I can afford to power a gm70 12 hours a day like I like to run my tv system. How I had planned. Power in my area like most places I guess is going up fast. This week I got my bill 600$.
I agree I shouldn't part with them. I hope they will work well at lower currents. I would like to try them with smaller tubes like 2e22 > 211 at the largest. In my experience every time I use a smaller tube with a larger trans it sounds better. I suspect that most tube amp trans power and outputs are for matters of economy half as big as they really should be. Perhaps I will just try them and see what tube will work best in them rather then taking up more of his time typing an emails.
I have 2 separate output windings as requested to monkey with speakers. Perhaps at 65 henneries I could wire them for 15k 80 ma for 211.
It should tell you something.
Transformers are time consuming to wind by hand and work right.
I tend to buy "things" rather than "possibilities". I will call someone and ask what they have on hand that can ship today. If it is not there, there is always a pretty good chance that it will never be. My feeling is that the winder should have at least a couple of the basic things they sell pre-made. If you want them to design and wind something special, a year does not seem all that odd. They should, however, tell you this.
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