Only there is no publicly known circuit for the 458, it is just pure Hungarian fantasyNot saying it is a bad amp, not at all, but it most probably bears no particular resemblance to the 458.
ah, pure Hungarian fantasy?
I did not know .
I had seen on this forum a Hungarian scheme that I had criticized because it looks like a bad evolution of 108.
But what I have is very different, maybe not better, just different and more interesting
What I did I purchased 1 complete Chinese clone and two bare pairs of the basic, unchanged NHB-108, Now I am expecting the third pair of the same configuration. My reasoning was to use the completed clone as a starting point and then build a clone from original components: I have played with one pair but now I want to rebuild it based on data I have gathered mostly here. I do not intend to try with "mutant" boards because I do not see much incentive in higher power as the maximum I need to listen is 10 Watts, perhaps up to 20, not more.
What my gut feeling says is that more you change this board, worse it behaves. Perhaps all it needs is good "kosher" components.
What I have noticed is that several basic parameters have changed in each clone generation but the topology has remained the same and as far as I know it is exact the same as the original. My expectations are to extract the maximum possible from this basic board and equip it with a fine chassis which will be good enough to enter my entertainment room. I plan to use it to feed midrange and tweeters whilst I will leave bass section to KSA-50, alternatively Accuphase A-60 if I succeed with this new project.
Last edited:
Let me tell you what I really mean with "mutant" board. Just look at the image below. At the left is the familiar topology of NHB-108 board and on the right you may see an attached "improovement". Even a newbie like me can observe a stark difference in expertise burried into the original and amateurish topology of straightforward implementation of the "mutant" part at the right side. It simply doesn't seem to be right. Just like the seventh finger on a palm of a mutant. Something artifitially added just for sake of "improovement".
Attachments
Last edited:
If you mean the circuit you posted in #537, then yes, it is pretty much the same as the earlier iterations of the Hungarian circuit. Do you have reasons to believe this corresponds to an actual 458 circuit?
Here it is, for comparison purposes
Attachments
Yes, one of my friend owns 458, I did some reverse engineering and measurement, pretty much like that, but not exactly identical.
As you can see, I have finished the PCB iteration of 458 clone, 2 AVX supercap were used.
My simulation of the circuit says its fine to sing. However, I am quite busy to finish and test the 458 clone project. Now, I finally get some time and started to start soldering works.
I will keep you guys posted once I complete the job.
Attachments
Last edited:
We have finished the PCB designs with all the supplies, as usual, stabilized, including the final ones.
We are waiting for them to arrive
In what way is it not the same? Don't tell me the 3-term regulators make it a new circuit.
it's not the same it just means it's different NOT that the genesis is completely different.
trimmer for offset, input capacitor etc
A scheme can be refined in micro or macroscopic details.
The Hungarian pattern, as per the definition of the forum, looks like a 108 with the addition of a few pairs of endings, which I already did and published the pattern.
Spectral also has the same pattern as the Hitachi book of half a century ago, but is it much more refined than the book, or not?
Now this is a completely different circuit compared to the 108 voltage amplification part, just count the transistors.
If the temperature stability of the offset is similar to the 108 i would rather use manual offset adjustment as the supercaps in that critical spot terrify me.
Would you please rephrase your Italian English? Very hard to read a bunch of single words.
By "pattern" I suppose you mean circuit or schematic.
Reading series of your reply, I really don't understand what you are trying to imply due to poor English level.
I recall you criticising that circuit. in English "it is a real hit" means "it is a real success". Is this what you want to say?
Where can we find the 458 circuit?
The huge transformers and the two six-packs of blue cans with gold bars to connect them is to justify the price for re-selling a circuit mostly copied from Studer.
mah, what to say.
I think the offset maintained at ZERO by the supercap is nonsense, but almost everyone does it with a signal ground capacitor, even with other much more trivial schemes.
Many have the inlet condenser, but, I think, it is always better, when you can, to eliminate it. It is clear that if it is not possible it is a problem and at least we choose a decent capacitor, certainly not 2 of those Wima in parallel.
And here we deviate on the scheme and technical decisions to make it stable and reliable.
I add that the 108 is an excellent condensate of limitations
I.m sorry , GOOGLE traduttore
I say that what differentiates one scheme from another is the details.
Speech that applies to the 3 schemes we are talking about, the 108, the 458 Hungarian, the 458 - mine -.
Analogous speech for Spectral Goldmund, Norma etc, all derived from Hitachi application notes, but all very different in more or less important details
Last edited:
It would be really, really nice if you can share a couple of the multiple pictures you have no doubt taken
Or at least one of the component side.