No it is not useless
- to have galvanic isolation as main function
- very top end HF cut/off
- to maintain right phase etc.
That is the case in older types but they are hard to find...
Maybe it is way to go with new VAC production with ring cores? Brown isolation on top of the core, Nagra use these types of cores, reported as very good.
...
I ahave some old little M new laminations VAC from last century.
They are just pins that heed to be pulled to VCC for the circuit to function.
If only using 74F and nobody never, ever fits a 74HC/ACT/LVC/LCX etc. you could leave them floating, but for CMOS they must be connected to Vcc.
Thor
There are better locations where to do that isolation with zero performance impact.
Transformers are not ideal for that, they tend towards a degree of unpredictability due to the complexity.
Yup. The number of factories still processing high nickel shrinks annually.
Magnetics are simply physics. There is no magic. Iron is iron, nickel is nickel.
80% nickel core
Iron core
1 Oersted = ~ 80A/m
Thor
To begin with, amorphous and nanocrystalline are different in properties. Saying that the high content of iron make them unsuitable for audio application is utterly nonsense.
You should know better. Start checking the differences in properties; their pros and cons.
Then figure out why these amorphous and amorphous related core materials are there in the first place. Think in terms of price of raw materials.
By stating that "if we had 80% nickel in amorphous or nanocrystalline cores, we might have something to discuss for DAC's" you merely demonstrate your ignorance. Think in terms of permeability, eddy current (core loss).
Nanocrystalline cores are iron-based, but with crystals controlled at nanometric proportions. Results in a lowish hysteresis core that I measured when I worked for a transformer company. Hence my use in the PCM DAC. I symply not resisted and make a pair when I worked there.
For instance, comparing cores using a simple current transformer: CT's it are sensitive to hysteresis and magnetizing current, due to intrinsic loose coupling. Nanocrystalline cores better normal cores with a outrageously very large orders of magnitude (in same model, it detects nA currents vs mA for normal cores).
Is not fully absent of permeability variation distortion when driven by medium impedances, but also, is very low and we can abuse near to relatively high inductions levels and even so results in decent low freq. distortion. Far from saturation, measures very low.
For instance, comparing cores using a simple current transformer: CT's it are sensitive to hysteresis and magnetizing current, due to intrinsic loose coupling. Nanocrystalline cores better normal cores with a outrageously very large orders of magnitude (in same model, it detects nA currents vs mA for normal cores).
Is not fully absent of permeability variation distortion when driven by medium impedances, but also, is very low and we can abuse near to relatively high inductions levels and even so results in decent low freq. distortion. Far from saturation, measures very low.
Wow, a outrageously beyond of the impossible parasitics for a 1:120 voltage ratio tranformer. Good luck for anyone who take such route ;-)
Hysteresys along with permeability variations rules out normal cores for this application (low level audio), for quality.
I did. NC/AM iron cores measure worse than medium nickel (50% Nickel) permalloy.
I can understand why they are foisted on the unsuspecting public, given the availability (or lack thereof) of high nickel cores and yes, they are better than plain transfomer (GOSS) steel. But then, we have Zick Nickel ferrite cores for power magnetics that would be a better choice if low distortion is desired.
OF COURSE, perhaps low distortion is not the design goal. Or we are not operating at 0mA DC. Then using GOSS is a good choice.
Like in the Neve 1073 Output:
For audio use AND low distortion, show me your test results, don't repeat marketing drivel at me (or others).
So, for a TDA1541 an AM/NC core transformer might be a good choice IF we:
Design for (say) 20mA DC current (18mA Bias over which 0...4mA are imposed) with a suitable winding structre and design to give the desired bandwidth and distortion (20-20k, +0/-0.3dB, < 90dBFS THD).
Tell you what, why don't you give us a 1:30 transformer on AM/NC core which has -90dB THD for an input level of -24dBu from a 33R Source at 20Hz-20kHz. No more than 150 USD per transformer. Or I can buy Nickel Cored instead.
Thor
Thor
Nanocrystalline with DC, obviously not without gap. Not a problem any cores (possible to add a regular spacer) but the toroidal ones (unless one make a cut on it).
Amorphous vs nano: amorphous have more sigmoid BH curves, so distorts more than nano at higher signals.
But also depends on the type, both cores exists in various grades (some dedicated to high power transformers for electric grid).
Same for ferrites, not try mundane ordinary cores: the distortion and hysteresis are HORREOUDOUS.
EDIT: also, with GAP, inductance drops, and needs to compensate with more turns... is good to watch the HF response. Normally it demands more interleaving of layers (for higher signal trafos).
Any doubt, is easy: testing... 😉
Amorphous vs nano: amorphous have more sigmoid BH curves, so distorts more than nano at higher signals.
But also depends on the type, both cores exists in various grades (some dedicated to high power transformers for electric grid).
Same for ferrites, not try mundane ordinary cores: the distortion and hysteresis are HORREOUDOUS.
EDIT: also, with GAP, inductance drops, and needs to compensate with more turns... is good to watch the HF response. Normally it demands more interleaving of layers (for higher signal trafos).
Any doubt, is easy: testing... 😉
You may should try the right implementation , components , etc...
after all we known that Sowters trafos works and measure very well when implemented as they sould be 😉
we also know that you had some fails ideas sometimes , while thinking they were absolutely good so why don't you look twice before judging something is bad ...........
.
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For transformer, you guys may wanna look at this thread 🙂 @bisesik makes excellent ones.
Hello everyone who looking for Sound!
After years of expirience the output transformers for current and voltage output DACs have been developed. Transformers tested with following DACs: ES90x8S/K2M/PRO/Q2M, AK4x9x, PCM56/58/63, PCM1702/04, AD1862/65, PCM1792, PCM1794A, TDA1541/43, DSC dac and others. Speaking in general, transformers can be suited for any current or voltage DAC both in SE or PP modes.
These transformers are made on high permeable cores, have the low DC resistance at desirable inductive impedance to achieve the best frequency response of the DAC. Transformers...
After years of expirience the output transformers for current and voltage output DACs have been developed. Transformers tested with following DACs: ES90x8S/K2M/PRO/Q2M, AK4x9x, PCM56/58/63, PCM1702/04, AD1862/65, PCM1792, PCM1794A, TDA1541/43, DSC dac and others. Speaking in general, transformers can be suited for any current or voltage DAC both in SE or PP modes.
These transformers are made on high permeable cores, have the low DC resistance at desirable inductive impedance to achieve the best frequency response of the DAC. Transformers...
It is not that. But every time I try to get a specific originally commodity priced CPLD or FPGA that something was designed for, I find it has gone out of being commodity priced mainline into a "special customer item", is NRND, EOL nothing that exists is pin- and binary-compatible with the old item.
A feed of the BCK before it becomes stopped clock BCK?
A feed of MCK pre-divided to 2.822/3.072MHz?
Is that little detail really THAT HARD to resolve? I didn't go into much detail because it's so obvious.
All we need is a continuous clock, derived in some way from MCK, that if divided by a factor 16 gives 176.4kHz/192khz.
IIS BCK happens to be the ideal source and would be present if the input is IIS or a separate IIS-2-SIM converter is used.
My experience with chinese companies like that for similar small modifications has been very negative.
I certainly think so. SIM only makes sense to push 384k/16Bit. For which almost no material exists.
If the WM8805 was still RND and not NRND I'd be tempted to just use WM8805 with 16Bit PCM Output with a 32FS BCK, up to 192kHz (needs software) and use USB-2-SPDIF boards and isolate all inputs with SPDIF Transformers and be done. This solution would work perfectly with the "insurrection" core but alas, too late.
Comtrue has a SPD Receiver chip they pitch as replacement, but alas, nobody uses it, the documentation is flaky and I have no idea if it offers as low jitter as WM8805 does in practice.
The SN74ALVC7804-25DL has a 512k X 18 FIFO, so if we use two, we can in theory have 16 Bit parallel with WCK and store 512 samples per channel. Of course in addition of acting as jitter killing FiFo it could also act to give the core of the IIS-2-SIM converter.
But that all looks like real work, without payback.
I have tried very hard to like the dual version, especially seeing I have the CD-Players to butcher sitting around. And while there are some small things I really like, overall it is just too much extra effort without material benefits. So back to single, basically insurrection + super capacitors, which seems really optimised based on the best we know, though not pleasing everyone.
Let me have a last gander at this.
Thor
Excellent! And he uses nanocrystalline cores (about the I/V, ops, output trafos thread link)😎
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Yep, not cheap but chews anything on market for the same price.
True, but tda1541a is obsolete as well, for quite a while now. This is not a dac to be reproduced 10 years from now. It's going to be made now and few hears down the road, and seldom after that as prices will be hiked up way too much.
I myself don't use SPDIF, but i'm implementing wm8804 on board since it's still available in sufficient quantities from official sources. And nothing else comes close to it currently.
Obviously.
The key point is, "Nanocrystaline" or "Amorphous" in itself is not attribute that make a core especially suited for audio and the ferromagnetic (mis)behaviour of the material is maintained (if reduced).
Now 80% be it as metalglass or other tech guarantees low distortion because of it's magnetic properties. So again, it is the material that matters.
I'll take 80% Nickel EI Lam's in 0.05mm over 95% Iron AM/NC ANY DAY in low level, no-dc offset applications.
SE Amp output Transformer? AM or NC please, but it's a totally different application and realistically 80% Nickel Lam's in a size suitable to a 80% nickel SE Output for 300B do not exist (and never did AFAIK) so there is no contest by default.
Of course, but we have some special grades that look and measure good, based on the samples I got. Available with precision airgap to order. Just not easy to wind on traditional machines. And I didn't really have any use.
Later we used in output inductors for Class D for my special filter, which is flat to 200Hz load independent, essentially zero distortion and which knocks down a 1.411/1.536MHz carrier by almost 120dB. The very small cores needed were cheap enough.
More sections.
Standard minimum sectioning for quality audio (I do not consider multifilar winding suitable for audio, based on listening) is 5 sections P/S/P/S/P with 7 sections preferred. Windings should alternate clockwise/counter clockwise and screens should be placed between sections.
Horizontal sectioning (Scheibenwicklung) as common in germany is also possible:
Finally, each horizontal section can be vertically sectioned so a maximum of 6 X 7 sections can be wound.
Thor
For transformer, you guys may wanna look at this thread 🙂 @bisesik makes excellent ones.
Hello everyone who looking for Sound!
After years of expirience the output transformers for current and voltage output DACs have been developed. Transformers tested with following DACs: ES90x8S/K2M/PRO/Q2M, AK4x9x, PCM56/58/63, PCM1702/04, AD1862/65, PCM1792, PCM1794A, TDA1541/43, DSC dac and others. Speaking in general, transformers can be suited for any current or voltage DAC both in SE or PP modes.
These transformers are made on high permeable cores, have the low DC resistance at desirable inductive impedance to achieve the best frequency response of the DAC. Transformers...
https://www.diyaudio.com/community/threads/output-transformers-for-dacs.327794/#post-5562787
Just passes the 16 Bit requirement at 0dBFS & 1kHz. At 20Hz not shown, but I entertain doubts.
At 300 USD/pcs for 1:1 I'm unsure what is the point.
Even if the 1:16 were available I could still find a pro-audio 1:30 Mic Step-up with similar 1KHz performance for around 100 Bux each. For 300 Bux each the Mic Ste-ups available as improved replica's are insane.
Perhaps it's just that I distrust "audiophile" anything, my experience has been it's overpriced, underperforming and overhyped. Good quality professional/commercial items do no worse and often better, at much lower prices...
Thor