Thanks for bringing this up. I like keeping track of global NFB free designs but this one has missed my attention.
I think it's a much bigger challenge to design and build a really good sounding amplifier without GNFB. The best amplifiers are all Class AB built with strong feedback, like ASR Emitter, Halcro, Audionet, FM Acoustics, all of these sounds perfectly clean and natural without any listening fatigue. So GNFB is not from the Devil.
To answer Hattori's question in short (from Deletraz's point of view)
1. Neither the extent nor the profile of IMD and THD has a real correlation with sound quality. Keeping them at a sufficiently low level (0.1%?) is just enough.
2. Trying to keep time and phase related distortions as low as possible. So you will preserve the temporal integrity of music.
3. Use as wide bandwith as possibble to minimize TD without using GNFB.
4. To acheive this use fast and linear BJTs instead of FETs and
5. Use several small but local NFB loops, instead of a bigger and slower, global NFB loop. This approach greatly improves signal transfer speed and propagation delay time.
1. Neither the extent nor the profile of IMD and THD has a real correlation with sound quality. Keeping them at a sufficiently low level (0.1%?) is just enough.
2. Trying to keep time and phase related distortions as low as possible. So you will preserve the temporal integrity of music.
3. Use as wide bandwith as possibble to minimize TD without using GNFB.
4. To acheive this use fast and linear BJTs instead of FETs and
5. Use several small but local NFB loops, instead of a bigger and slower, global NFB loop. This approach greatly improves signal transfer speed and propagation delay time.
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Dears, a thread about Dartzeel, please post your conclusions and preferably your boards and designs on it, and not just theories. I posted here the graphs of the made clones, can you tell something about them? Your opinion is valuable when supported by photographic materials. With respect (no offense) to everyone.
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I am quite certain i have posted measurements of my clones somewhere in this thread. They are pretty much in line with what Stereophile measured. In any case the measurements are only a function of the transistor selection and will not differ between minor board layout variations. Passive components will also make no difference as long as their nominal values are reasonably accurate.
What measurements do you want to compare?
Rules breaking posts and their collateral have been removed. Further rule breaking posts will be removed and may result in thread closure.Is there a thread for the ASR Emitter amplifier here on diyaudio, as well?
When I search here for "ASR Emitter" I get 5000 overwhelming hits...
analog_sa Hello. I'll try to ask you something else. Your red board (clone-clone) with stabilizers differs in sound from the green board (clone of the original, if you made it), and if so, how much? Only without graphs, but in fact. Will there be an increase in the quality of manufacturing this amplifier according to your upgrade? And I would like a photo of your board, what parts you used.
Russian-speaking with a translator, but they also swear there. ????????? Dartzeel NHB-108 (????????? ?????, ?????? ????????? ? ????) [1] - ??????????? iXBT.com
????????? Dartzeel NHB-108 (????????? ?????, ?????? ????????? ? ????) [1] - ??????????? iXBT.com
Right now I am finishing the final design based on suggestions published at the very beginning of this conversation. The most useful are very practical guidelines by Danny_66.Dears, a thread about Dartzeel, please post your conclusions and preferably your boards and designs on it, and not just theories. I posted here the graphs of the made clones, can you tell something about them? Your opinion is valuable when supported by photographic materials. With respect (no offense) to everyone.
I have published my measurements but I plan to publish even better results of the work in progress soon.
I have adder some changes in power supply and wiring.
As previously concluded, this clone is a fine amplifier that deserves time to conceive adequate layout and use of decent components. The results are indeed rewarding. Though, opinions on that may differ in accordance to individual taste.
I am very happy with the results.
I do appreciate all help I have received here from members who have shared their knowledge.
That's a good Idea. I have also considered that but it appears that adequate wiring and good power supply may eliminate problems. Meanwhile, I have made substantial progress and will publish results soon.
Regards
Erlend!
I'm glad you still persist. In fact, I have finished the design and have made tests. Just, I have lots of other obligations and tight schedule doesn't allow me to write a report about the progress.
Soon, I will do that.
Hattori,
thanks for the info about L12-2. That's a good find. I have already ordered everything and in addition to that, a similarly good board MX50SE. Both great projects.
Regards
I'm glad you still persist. In fact, I have finished the design and have made tests. Just, I have lots of other obligations and tight schedule doesn't allow me to write a report about the progress.
Soon, I will do that.
Hattori,
thanks for the info about L12-2. That's a good find. I have already ordered everything and in addition to that, a similarly good board MX50SE. Both great projects.
Regards