Even with BD139 I can already tell that there's more nuance in everything, especially voices without driver transistors. In many ways I already prefer it over how I have been playing for the last couple of days. And it's only gonna get better once I replace them with BD441.
Does removing driver transistors make this a follower then? It seems mine will remain without driver transistors.
Does removing driver transistors make this a follower then? It seems mine will remain without driver transistors.
Most people would deny that the Q410, the bias control, is involved in the sound - they even deny that components have a significant influence on the sound;-) But we always listen to the current, the cleanliness of the current, influenced by material, design, cross-sections...) or whether the 3-stage preamplifier is also running. If it is the pure one or two stage follower, connected to the large 2 x 28 volt psu, with a CR-HF-killer at the output (100nF - 10 Ohm) it should, in my experience, run stable. The input of this follower could also be fitted with an HF-killer, but I haven't had to do that yet.
In this NAD, R455 and R456, 1 Ohm, are still connected to the collector of the NPN of the output stage. This small resistor also makes the follower unsymmetric. I would also connect such a resistor to the PNP collector at the beginning. Later, when everything is running smoothly and safely, remove or reduce it - then simply go by sound and tuning. Or simply place it on the emitter side. Who knows if it makes a difference in terms of sound;-)
By the way: compared to good amplifiers, the followers sound minimally "lifeless", less "punch", but highly pure, chiseled like a block of sound, with a peculiar, slightly colored aura. Amplifiers, like very good oil paintings that have been given a final contrast with a few splashes of white dab, can appear clearer, more contrasting, more vivid. But they lack this "aura", this highly pure, undistorted quality.
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Even these solder joints can be further refined. But it is enough to do it this way to take a step forward in terms of sound. If it's about audio, then at least like this.
I'm assuming what I have here is a follower. One surprising thing that I experienced during the night when I was listening at very very low level, half asleep, is that I was hearing everything so well, it was like it was playing louder, but it was playing very silently. Also when listening to voices, there is indeed much more nuance and magic you could say. Truly quite interesting. As for the macrodynamics, I haven't listened loud enough to really notice, but yes there seems to be a difference, during the three or so minutes that I have had the amplifier running with the correct transistors, I think I immediately noticed a little bit less dimensional punch and stuff, but relatively speaking, while that punch can be satisfying, while the depth and dimensionality to the bass can be very fun, the amount of information we are losing there relative to the amount of information we're losing in the mids and the highs, is incomparable. I have to admit, the fun factor is very important. But since I'm most likely going to be bi-amping or even tri-amping (after I build big bass horns or at least big woofers with their own cabinets) my system at some point - this is much less of consequence. I'm still tempted to get a Class D for the lower frequencies, but the problem with that is that my crossover is pretty high which would be around 1.5 kHz to 1.7 kHz depending on how I want to set it up, but below 1.45-1.5 my tweeter starts loosing it's performance. However these amplifier modifications are proving to me that I have a superb amazing beautiful tweeter to play with. It's the tweeter found in L100 and L82 classic (it crosses at 1.7 kHz in the latter). Not only does it play absolutely beautifully, but it's also designed for some serious abuse as far as I can tell. There is some kind of ferrofluid cooling and in general JBL is for people who like to crank things up but not burn them. Given that I already burnt a few transes here, that might as well have saved my *** already. Maybe I should reintroduce the fuses while I'm playing around.
By the way, where I said that BD139 have a lot less body and everything is flatter, this could actually have been due to the fact that I went from having driver transistors to not having them when I switch to listening to BD139 again on the previously burned channel.
There does seem to be a bit of a lack of bite and intensity to metal strings and electric guitar though, so that's not a tradeoff I'm very excited to take, but we'll see how it does with BD441 again. There's more fluidity, but it does have a cost.
By the way, where I said that BD139 have a lot less body and everything is flatter, this could actually have been due to the fact that I went from having driver transistors to not having them when I switch to listening to BD139 again on the previously burned channel.
There does seem to be a bit of a lack of bite and intensity to metal strings and electric guitar though, so that's not a tradeoff I'm very excited to take, but we'll see how it does with BD441 again. There's more fluidity, but it does have a cost.
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Nice thread here, I am pleased that so much sound experience is collected;-)
20 - 25 years ago I had built the Jericho horns (Klang + Ton). And because they rattled so much, I covered them properly with fabric and damping materials. And because the rapple was still clearly audible, I rebuilt these horns: Walls filled with sand. > 90 kg of sand per speaker, total weight > 160 kg. Then there was some peace and quiet. But large wooden bodies and wooden walls and surfaces can be heard very clearly and de-color the sound enormously. This applies to all speakers made of wood and wood-based materials.
A few more basics for speaker construction and tuning:
https://www.diyaudio.com/community/threads/cumbbs-koans.393926/#post-7224083
20 - 25 years ago I had built the Jericho horns (Klang + Ton). And because they rattled so much, I covered them properly with fabric and damping materials. And because the rapple was still clearly audible, I rebuilt these horns: Walls filled with sand. > 90 kg of sand per speaker, total weight > 160 kg. Then there was some peace and quiet. But large wooden bodies and wooden walls and surfaces can be heard very clearly and de-color the sound enormously. This applies to all speakers made of wood and wood-based materials.
A few more basics for speaker construction and tuning:
https://www.diyaudio.com/community/threads/cumbbs-koans.393926/#post-7224083
I would buy a few different values as they are a great way to set up and optimally adjust circuits quickly and easily. 200 Ohm, 1 kOhm, 10 kOhm, 50 kOhm, 100 kOhm, 1 MOhm. I think these are good values to start, to be able to adjust most things precisely. Manufacturer doesn't matter.
My BD441/442 got stuck for like 10 days on their route to me. Next week I expect to pick them up.
22mF KEMET PEH200KD5220MU2. Definite improvement in sound. I expected it more to be in bass but bass is mostly similar, I find that the vocals improved the most - less warmth, more cold and black, everything's more focused, more dimensional, more body, more detail. Truly a big improvement in the vocal department. Much more realness (due to depth and dimensionality but also detail). The highs too seem to have benefitted a good amount. More sparkle/shimmer and effortlessness and reality and detail. Actually the whole character of the sound is very different. Much blacker, but also kind of a... A different vibe for sure. But much more dimensions so it's a welcome change. The warmth is gone, but the detail and body captures your attention in a pleasing way. A more serious presentation for sure.
I thought I'd be able to solder them, but for now it seems gold plated O ring connectors with brass screws will be my best option.
Would like to compare more with the originals or the smaller ones you said played well for you.
Also if I'm not mistaken the previously mentioned vynil-like pops might have disappeared completely. Indeed that seems to be the case. And seriously the highs have improved quite drastically. Everything's more here now, the instruments are more in my room and lifelike.
22mF KEMET PEH200KD5220MU2. Definite improvement in sound. I expected it more to be in bass but bass is mostly similar, I find that the vocals improved the most - less warmth, more cold and black, everything's more focused, more dimensional, more body, more detail. Truly a big improvement in the vocal department. Much more realness (due to depth and dimensionality but also detail). The highs too seem to have benefitted a good amount. More sparkle/shimmer and effortlessness and reality and detail. Actually the whole character of the sound is very different. Much blacker, but also kind of a... A different vibe for sure. But much more dimensions so it's a welcome change. The warmth is gone, but the detail and body captures your attention in a pleasing way. A more serious presentation for sure.
I thought I'd be able to solder them, but for now it seems gold plated O ring connectors with brass screws will be my best option.
Would like to compare more with the originals or the smaller ones you said played well for you.
Also if I'm not mistaken the previously mentioned vynil-like pops might have disappeared completely. Indeed that seems to be the case. And seriously the highs have improved quite drastically. Everything's more here now, the instruments are more in my room and lifelike.
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22 mF is quite an statement. That > 3 times more than the originals, and that alone is audible: generally much larger space, much higher resolution, finer colors, more space around the sources. Something like this. But the basic sound characteristics can only be determined in a comparison with several other capacitors.
There will be some who will grumble about such high capacity. But the ear decides. Another possibility is the parallel connection: if one capacitor sounds too dry or dull, then two, or three, in parallel will be smoother and more merciful;-)
If there are screw connections, then also try plastic screws and plastic o-rings, because if other metals are added, the current path becomes more undefined. This can sound good at first, also due to the materials: instead of dull aluminum, something sounding brass, steel, which also counteracts the sound of wooden materials of e.g. loudspeakers, but it robs the definition, the high resolution is lost. That's a question of tuning later.
My PEG227s are due to arrive tomorrow. I will compare them with the PEG124s. I will test and tell.
There will be some who will grumble about such high capacity. But the ear decides. Another possibility is the parallel connection: if one capacitor sounds too dry or dull, then two, or three, in parallel will be smoother and more merciful;-)
If there are screw connections, then also try plastic screws and plastic o-rings, because if other metals are added, the current path becomes more undefined. This can sound good at first, also due to the materials: instead of dull aluminum, something sounding brass, steel, which also counteracts the sound of wooden materials of e.g. loudspeakers, but it robs the definition, the high resolution is lost. That's a question of tuning later.
My PEG227s are due to arrive tomorrow. I will compare them with the PEG124s. I will test and tell.
If this relates to the NAD amp, removing the drivers and turning the double EF into a single EF will cause all sorts of unpleasant things happening to the VAS leading to a severe rise in distortion. Little wonder it now sounds loud even when it's soft.
Unlike positioning the holes of transformers away from cats, this kind of stuff is easily tested in a simulator. Have you considered learning how to use one?
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TBH I still don't understand the entire signal path and power source paths in this amplifier. Might be tedious to simulate the entire amp by entering every component. No, I have not considered such software. Any freeware you'd recommend that I should be aware of?
I do get distortion, but with new caps it's much less. However - yes, removing driver transes did introduce more weird audible things and less stable performance when played loudly. I intend to listen more after adding them back, then see what differences are really audible. But playing extremely silently without driver transes it sounded very alive for the low volume level which was the appealing part for me. Class D for example sounds very dull on low volume IME. Maybe that's what this configuration is for - extreme low level listening for night time. The work is not finished in my case, so I'm still going to experiment and learn before settling on the final solution. I have a feeling I will be using this amp only for the tweeter anyway once I get an 8ch DAC. And it plays the tweeter very very well in many respects so we'll see, if I find something plays the highs better I'll just pass it around among friends to play with. The way it is it's already pretty special. As long as your speakers are resolving enough to hear it. It may also turn out to be quite a special headphone amp. Depending on the purpose I'll decide on final version of the amp. A lot of this (for me) is about playing around and learning, more than trying to achieve a specific goal. Thanks for the suggestion.
I do get distortion, but with new caps it's much less. However - yes, removing driver transes did introduce more weird audible things and less stable performance when played loudly. I intend to listen more after adding them back, then see what differences are really audible. But playing extremely silently without driver transes it sounded very alive for the low volume level which was the appealing part for me. Class D for example sounds very dull on low volume IME. Maybe that's what this configuration is for - extreme low level listening for night time. The work is not finished in my case, so I'm still going to experiment and learn before settling on the final solution. I have a feeling I will be using this amp only for the tweeter anyway once I get an 8ch DAC. And it plays the tweeter very very well in many respects so we'll see, if I find something plays the highs better I'll just pass it around among friends to play with. The way it is it's already pretty special. As long as your speakers are resolving enough to hear it. It may also turn out to be quite a special headphone amp. Depending on the purpose I'll decide on final version of the amp. A lot of this (for me) is about playing around and learning, more than trying to achieve a specific goal. Thanks for the suggestion.
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Well, yeah, I don't know the reason why, but the right channel burned after 2 minutes of playing in this configuration and also it had a few louder, more dangerous sounding audible things (I suspect my psu caps may have had an influence on this behavior since changing them removed certain kinds of pops and noises) before finally burning the output resistors. On the other hand, I think cumbb has been playing in this configuration without issues. I don't know if he has tried to crank it all the way up with more busy and bass heavy music.
I'll report back when I experiment and have more experience in both configurations.
I'll report back when I experiment and have more experience in both configurations.
Step by step;-)
This thread is also multifaceted: both make the NAD an audio device - up to about # 50 - and also use it as a basis for further experiments. But all this has been clearly marked verbally - a pity if one don't follow threads, or don't read across, and also don't know about practical doing and development processes and audio - and more)-;
... or is exposed to EMF of electronic devices for too long or constantly - one can also find out about the health effects of EMFs;-)
This thread is also multifaceted: both make the NAD an audio device - up to about # 50 - and also use it as a basis for further experiments. But all this has been clearly marked verbally - a pity if one don't follow threads, or don't read across, and also don't know about practical doing and development processes and audio - and more)-;
... or is exposed to EMF of electronic devices for too long or constantly - one can also find out about the health effects of EMFs;-)
To "my" NAD at present - to renew orientation - for non-followers(-:
I have built a pure complementary transistors push-pull follower: Half-wave balanced (and two power supply units, voltages, +/- 28 V) consisting of only two transistors (BD441/442), one 16 kOhm resistor each (via trimmer) collector - base, still the bias transistor and its trimmer, and one coupling capacitor each to the base via which the signal comes in. I have the RCA sockets "Main amp" (or similar) as connection. No HF killer at the input.
The original HF-killer is still connected to the output, 100 nF, 10 Ohm. In my experience, this follower would also work without it.
The thing plays great, nothing cracks, nothing gets louder or quieter. The follower plays with an enormously high resolution, fine, mild, with a peculiar aura, and not loud (followers/buffers do not amplify voltage - nearly not;-) - but also with the break in the sound image typical of complementary transistors;-)
As mentioned, everything else will follow. After the search for suitable PNP transistors for the pre amp and electrolytic capacitors.
I have built a pure complementary transistors push-pull follower: Half-wave balanced (and two power supply units, voltages, +/- 28 V) consisting of only two transistors (BD441/442), one 16 kOhm resistor each (via trimmer) collector - base, still the bias transistor and its trimmer, and one coupling capacitor each to the base via which the signal comes in. I have the RCA sockets "Main amp" (or similar) as connection. No HF killer at the input.
The original HF-killer is still connected to the output, 100 nF, 10 Ohm. In my experience, this follower would also work without it.
The thing plays great, nothing cracks, nothing gets louder or quieter. The follower plays with an enormously high resolution, fine, mild, with a peculiar aura, and not loud (followers/buffers do not amplify voltage - nearly not;-) - but also with the break in the sound image typical of complementary transistors;-)
As mentioned, everything else will follow. After the search for suitable PNP transistors for the pre amp and electrolytic capacitors.
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Experimentation may be all well and good, but you can already see where this line of experiments is leading. Anyone who can apply just a little basic math can see it.