Let's See Your Transformers!

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FullRangeMan

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Re: Let's See Your Transformers!
« Reply #100 on: 10 Jun 2015, 07:36 pm »
HiB is laminate or a solid block píece?
Dont know if the 6C33 worth the labour.
Let me know about GM70 C core OPTs and power.

E55l2

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Re: Let's See Your Transformers!
« Reply #101 on: 11 Jun 2015, 02:44 pm »
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« Last Edit: 7 Jun 2022, 06:20 am by E55l2 »

Docere

Re: Let's See Your Transformers!
« Reply #102 on: 8 Jul 2015, 06:55 am »
Hi all,

Output transformers for my 6C6-2A3 SE amp build have arrived. They are pretty large for what will be a 2 Watt amp. 5.9 kg each of custom nanocrystalline double c-core!





Now waiting for chokes and power and filament transformers to clear customs. I think it is time to get my project underway!

Cheers,
Ray





FullRangeMan

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Re: Let's See Your Transformers!
« Reply #103 on: 8 Jul 2015, 07:44 pm »
Wow, what is the brand/model?
Any additional info on the C core?

Docere

Re: Let's See Your Transformers!
« Reply #104 on: 8 Jul 2015, 08:27 pm »
These are the top transformers from J and K Audio Design, located in Malaysia. They seem to have a very thorough technical approach to design and their service has been excellent. These transformers were very well packed – triple-boxed and heavily stuffed with each transformer neatly wrapped. Jolin has been a pleasure to work with.

They have worked closely with their core supplier to get a type of nano-c that is to their liking and ensure consistency – I am pretty sure this is not an off-the-shelf core. It has a 4K2 primary (for loading a 2A3 run at 42mA and 250V P-K) and is gapped for 45mA, but can comfortably run a little over 50mA. Looking and the spec-sheet and measurements in circuit, at 42mA it has 45+ Hy inductance and a low primary winding resistance. The FFT shows much wider response than the specified 5Hz to 80kHz (-3 dB) with a smooth roll-off in the highs. Their measurements look conservative. I can’t wait to get this in circuit and hear how it sounds.

Link to website: http://jandkaudiodesign.blogspot.com.au/

Click on the “Transformers” link on the left side of the page.

Cheers,
Ray
« Last Edit: 15 Jul 2015, 08:01 am by Docere »

FullRangeMan

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Re: Let's See Your Transformers!
« Reply #105 on: 8 Jul 2015, 08:38 pm »
Thanks for the link Ray. This is what I call a just right winding:

Docere

Re: Let's See Your Transformers!
« Reply #106 on: 14 Jul 2015, 06:03 am »
Yes, that looks very elegant!

Some more iron for my next build has arrived. These two beasts are 7Hy chokes with custom noncrystalline c-cores. They have ~10 Ohm DCR (low DCR for quickish power supply recovery times) and are potted in the same case size as the output transformers... but weigh even more at ~ 6.5 kg each.

Now that parts are accumulating I realise this build is really very ambitious and I hope the circuit is worthy of such parts. Well, at least I can re-use the iron (and chassis and some other parts) in a different circuit if desired.






Now I am awaiting delivery of the power transformers (B+ and filaments).

Cheers,
Ray
« Last Edit: 15 Jul 2015, 08:02 am by Docere »

Docere

Re: Let's See Your Transformers!
« Reply #107 on: 15 Jul 2015, 06:59 am »
The final delivery has cleared customs and is now at home. As you can see, these are the power and filament transformers. I had the primaries tapped for both 230V (our "nominal" voltage and what I set my PurePower 1500+ to) and 245V, roughly the average voltage out of the wall.


This is the 6C6 and 2A3 filament transformer nicely wound on neat Z11 cores. They feel far better assembled and heavier than the Hammond filament transformers I have had in hand; solid.




This is the top B+ (and rectifier filament) transformer wound on Super Hi-B double c-cores. They are well over-specified for my use. I have had the B+ secondaries tapped for both direct and capacitor coupling... just in case the direct coupling does not work out. There are some connections I am unfamiliar with (G and the 2x 0-2.5V pairs, which I assume can be wired for 5VCT), but I have no doubt all is fine.




Well, that is the transformer set for my evolved  6C6-2A3 mono-block build. I have ordered most of the other components - when they arrive I will plan and draw the layout then have the Delrin sub-chassis and steel chassis fabricated. Fun times ahead.

Thanks for taking the time to look.

Cheers,
Ray
« Last Edit: 15 Jul 2015, 08:38 am by Docere »

FullRangeMan

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Re: Let's See Your Transformers!
« Reply #108 on: 4 Aug 2015, 02:13 am »
Docere,
Why did you chose nanoC and not SuperHiB?
Is nanoC a better core than HiB?

E55l2

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Re: Let's See Your Transformers!
« Reply #109 on: 7 Aug 2015, 05:34 pm »
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« Last Edit: 7 Jun 2022, 06:20 am by E55l2 »

FullRangeMan

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Re: Let's See Your Transformers!
« Reply #110 on: 8 Aug 2015, 12:04 am »
Nanocrystaline material have much lower core losses: hysteresis (material) and eddy current (thin laminations)

The question is how important is this for a SE audio transformer? For SE the transformer is biased with a current and because of that there is always a magnetic field. So the advantage of the much lower hysteresis loop of nanocrystaline materials is highly reduced in this case, only for very low frequencies at very low exitation you can measure (and maybe hear, we talking about  8Hz- ...20..30Hz) a differance. But because nanocrystaline materials can not have a high exitation level (1,25T vs 2T for SiFe) copper losses are much higher.
At higher frequencies the advantage of the very thin core laminations is still an advantage but i think also not so important as many people think. The exitation level at higher frequencies drop with frequency so the eddycurrent loss is reduced too, and the multilayer winding technique reduce the problem too. Remember that most transformers have "high" thd at low frequencies (<100Hz) and not for mid/high frequencies.

The biggest advantage for hightech materials is for very low signals and specially PP (ac signals only)

Anyway i like that J&K make such transformers, they look better then anything else i have seen from the commercial manufacutures before.
I would like to see measurements from Docere to comfirm the data from J&K.
Thanks E55l2 for clarify my doubt again.
I always appreciate your technical explanations and its practical application to HiFi.
Your tech background has been very useful to us.
Thank you. :thumb:

So Iam understanding HiB or SuperHib is a better core.

E55l2

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Re: Let's See Your Transformers!
« Reply #111 on: 8 Aug 2015, 08:41 am »
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« Last Edit: 7 Jun 2022, 06:21 am by E55l2 »

FullRangeMan

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Re: Let's See Your Transformers!
« Reply #112 on: 8 Aug 2015, 11:10 am »
hiB is not a better core, a different core what for SE can almost do the same. In some parts better, other a bit worse. But, much more economical.
Interesting it, do HiB are more cheaper than M6 SiFe?

E55l2

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Re: Let's See Your Transformers!
« Reply #113 on: 8 Aug 2015, 12:09 pm »
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« Last Edit: 7 Jun 2022, 06:21 am by E55l2 »

FullRangeMan

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Re: Let's See Your Transformers!
« Reply #114 on: 9 Aug 2015, 12:48 pm »
M6 is cheaper and less good then HiB.
Thanks  :thumb:

Docere

Re: Let's See Your Transformers!
« Reply #115 on: 24 Aug 2015, 10:17 am »
Sorry to be late to this. I checked for replies for a couple of weeks, then moved on to other things -  actually, a sore back  :)

I decided on nano-c because I like J&K's description of the musical presentation relative to their other products. Without disclosing details of personal correspondence, the nano-c SE output transformer excels at resolution, bass extension and solid mid-range. J&K also described their chokes, saying that the Super HiB is authoritative and the nano-c is finessed. J&K did not try to up-sell me on the nano-c; they also recommended cheaper models they believe to be suitable and high-performing. From memory, the difference between the cost of a J&K level 3 nano-c and Super HiB SE output transformer of similar specifications is not great; I think at this level much if the cost is in the winding, casing etc.

I trusted J&K's descriptions and went with what I could afford, while I can afford it, as a transformer purchase that will last until pass from this earth. It is re-affirming to hear E55l2 comments about his confidence in J&K. Now I need to get moving on the amp.

Hope this helps somewhat.

Cheers,
Ray

FullRangeMan

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Re: Let's See Your Transformers!
« Reply #116 on: 25 Aug 2015, 12:00 pm »
Thanks Docere for your detailed post and your personal preference.
The JK site also interesting it very oriented to sound quality.
I liked that.

Docere

Re: Let's See Your Transformers!
« Reply #117 on: 26 Aug 2015, 11:16 am »
No problem FRM.

J&K strike me as an outfit that understands both the engineering and sonic sides of design; they seem to do a lot of engineering and listening.

Cheers,
Ray

Steve

Re: Let's See Your Transformers!
« Reply #118 on: 26 Aug 2015, 11:00 pm »
Test chassis with OPT in backround. I know, not great looking but need to change parts etc for testing.


I know the output graph below is the representation of an entire test amplifier and not just the OPT, hope it is ok as it is under actual conditions. The amp is supplied with a 10khz rectangle wave input. The load is a Dayton "non-inductive" 8 ohm resistor. (Connected to the speaker no noise with ear on the cone itself.)

10khz output with Dayton 8 ohm "non-inductive" load resistor, low level. I do not know the residual inductance of the load resistor.


Cheers
Steve
« Last Edit: 7 Jan 2016, 07:58 pm by Steve »

E55l2

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Re: Let's See Your Transformers!
« Reply #119 on: 25 Dec 2015, 12:52 pm »
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« Last Edit: 7 Jun 2022, 06:21 am by E55l2 »