Can we build something even better than Swiss Dartzel? What about "Hungarian" or "European" Dartzeel, better than the original "Revox" amplifier. This can be a hot topic.
I am looking forward to hear more from shany.
Is Supercap a different name for the SCNP that was added to NHB-108 version B? It was my understanding it was added to control DC offset so that it will not be necessary to adjust it after some use.
I just cannot find any such SCNP´s on Shanys schematic diagram. That is why I asked about that detail, just trying to understand if that diagram can really be of a 458..
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But what if such "bell or whistle" was just a distraction or misterious "feature" to justify price? Remember, the Swiss Über-wizard has copied and patented decades old Revox. I prefer to believe shany.
What do you expect to find? No SNCP component exists, it is a marketing invention.
Supercaps use the same symbols as normal electolytic capacitors and in Dartzeel as used in exactly the same fashion as electrolytics are used in the majority of amplifiers: to decouple AC from DC gain in the nfb network.
In Shany's circuit these are are the 10mF caps.
So why use supercaps? They are small, cheap, pack a lot of capacitance in a small volume, have low ESR over a wide frequency range, the low operating voltage is not an issue in this particular spot.
To the best of my knowledge no other manufacturer uses them for signal transfer and thus they are a bit of a wild card as far as sound quality is concerned.
The A version had a temperamental offset which proved a nuisance for users and dealers to adjust. By sacrificing some audio quality the issue was resolved. Marketing gave it a silly name.
I am not sure if the ver A were retrofitted with capacitors. If yes, this would explain the use of supercaps: normal electrolytic caps would have been physically impossible to fit.
BUT how come this Chinese seller has two versions of the NHB-108, one with SCNP and one without? There is a picture of the SCNP on this version of the NHB 108:
Swiss NHB 108 Post Power Amplifier Copy One Without Negative Feedback Amplifier Circuit Kit 2 Tubes Parallel Output|Amplifier| - AliExpress
"10. SCNP midpoint stabilization module"
And I cannot understand how a regular capacitor can replace a component with three legs?
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Chinese will produce even more additional versions, just if you are ready to place an order. They are good at making PCBs and ... marketing. Shany is genuine, I know that.
And is Farnell in on the Supercap Conspiracy? 🙂
https://uk.farnell.com/avx/bz015b603zlb/capacitor-bestcap-60mf-5-5v/dp/1302034
That certainly looks legit, to me..
https://uk.farnell.com/avx/bz015b603zlb/capacitor-bestcap-60mf-5-5v/dp/1302034
That certainly looks legit, to me..
Yes, there is a version B that has a Supercapacitor, and, I think, two pairs of output transistors. Much like the Jay's Audio version from the Queensway store (on Aliexpress)
darTZeel NHB-108 Model One power amplifier Manufacturer's Comment | Stereophile.com
In the second last paragraph Hervé Delétraz mentions that "Also, in order to render the machine a little bit more "recommendable on a general basis," we added a DC compensation circuit"
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What isn't clear? That some supercaps have 3 terminals? That's because there are two caps inside in series with a centre tap.
The ones in Dartzeel i believe are 3 terminal but behave as 2 terminal. The third one is just to simplify mounting
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In any event it certainly looks as if the real 458 has two such metal gizmos. Why would they use them if they could be replaced with regular capacitors?
I am just trying to figure out if the schematic diagram is legit..
I have searched over and over again for Service Manuals for the 458 and for the 468, but have come up with nothing.
I am just trying to figure out if the schematic diagram is legit..
I have searched over and over again for Service Manuals for the 458 and for the 468, but have come up with nothing.
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Ok, this I did not know. That would explain why it looks like the two legs on the one side are shortcircuited by the resistor legs! I thought it was a bad photo/optical illusion of the SCNP version NHB-108..
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🙂
No ultra high end manufacturer has ever made a component level service manual public. The only servicing dealers perform is replacing boards and turning pots.
Such information devalues the brand and reduces revenue. Searching for it is an obvious waste of time.
Even manufacturers of more affordable audio keep hush about their premium products service info.
No ultra high end manufacturer has ever made a component level service manual public. The only servicing dealers perform is replacing boards and turning pots.
Such information devalues the brand and reduces revenue. Searching for it is an obvious waste of time.
Even manufacturers of more affordable audio keep hush about their premium products service info.
I see. That explains why I cannot even find service manuals for Yamahas top of the line products.
So how has the 458 circuit diagram surfaced? Reverse engineering? But even if you have high resolution photos of the frond and the back of a MB, how can you be shure it is not a multilayered card? Most computer MBs are multilayered, I believe. If I were Mr D. I certainly would try to hide/obfuscate some component connections on the latest model MBs to prevent reverse engineering considering the story with NHB-108.
Make no mistake, I very much hope shanes diagram is correct, of course!
So how has the 458 circuit diagram surfaced? Reverse engineering? But even if you have high resolution photos of the frond and the back of a MB, how can you be shure it is not a multilayered card? Most computer MBs are multilayered, I believe. If I were Mr D. I certainly would try to hide/obfuscate some component connections on the latest model MBs to prevent reverse engineering considering the story with NHB-108.
Make no mistake, I very much hope shanes diagram is correct, of course!
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I bought the Queensway version with two pairs. There is something very wrong with this. I will warn you do not buy it. There is almost no bias.
Which board with two pairs of output devices? All they have now is "finished board" with a single pair. I have purchased bare boards of the same configuration elsewhere and my amplifier works very well indeed. I have used components from reliable source. What went so terribly wrong?
I can say that for the 108 schematic, even though I did not copy it 1:1. I am a "tube guy" myself and thanks to analog_sa I started to experiment with dartzeel and now I can't pick a side soundwise.
Yeap, that's what my sim files show as well. Have you yet tried the Hungarian circuit yourself?
