Post by Bigman80 on Jan 29, 2022 11:08:27 GMT
When I bought my first Neurochrome 686 from Tom, I don't think I realised how much of an impact it would make. It didn't just improve the sound quality in my system, it also changed the way I thought.
This was the very first amplifier I had owned/heard that eradicated any preconceived notion in regard to valve VS solid state. In fact, to be honest, I wouldn't even know how to classify it in terms of what camp it would sit in, because it doesn't really sit anywhere that I would feel comfortable pigeonholing it.
I've had other amplifiers here. Of course I have! For we are audiophiles, and the thought of settling down with one amplifier for the rest of your listening days causes a slight murmur of doubt in the soul. However, that is what I am doing. Well, in the main lol
Looking at what sort of advances have been made in amplification since I got my first 686, has been disappointing. Hoping to find some new device that tears up the rule book. One that annihilates other amplification! Alas, it appears that whilst there are some setting the "Benchmark" in measurements, nothing really captured my enthusiasm. Purifi are making some fascinating devices too. They are on the cusp of releasing a new higher power PCB. It won't get my money though due to the huge bank of brass headers on the interlinking PCBs. Call it ridiculous, but the old nugget won't knowingly allow brass connections in the system now. Although I may still explore this design at a later date.
Other options were entertained, but my heart was always pulling me towards a new 686 build.
For this build, I wanted a larger chassis. One that could fit more capacitance, Speaker protection PCBS, a soft start PCB and two O-Core Transformers. The O-Cores will not be powering one channel each, but will be powering one phase each. I think that's how Angus explained it, lol.
Here is the case. Purchased from Aliexpress for a very fair price, it should be here in March, lol. Apparently there is a big holiday in Asia which is slowing everything down. :
Next thing I wanted to nail down was the capacitors. I have gone for 8x10000uf, 80v Kemet ALC10 Slit Foils. Here is the blurb:
"Conventional capacitors, being made of large, coiled, thin strips of aluminium, are prone to induce eddy currents across their conducting surface. These currents prevent the capacitor from doing its job optimally, thus degrading subjective sound quality. By introducing a series of tiny slits in the foil conductors, these eddy currents are dramatically reduced, therefore, improving the subjective and measured performance.
Modern electrolytic capacitors are designed for use in power supplies, so most aspects of their design have been optimised. Some advances in the design may not be beneficial in audio applications where the requirements of the capacitors are very different.
Slit foil capacitor research has also indicated that improvements in the general construction of the capacitors give better results in audio where the fidelity of the wave shape is very important. Great attention has been paid to the construction details which can affect the performance, i.e. foil type, its connections and mechanical construction"
I am not sure how much of this is actually true, but the life expectancy of this particular type of cap was a dealbreaker.
For the Transformer, I have stayed with the O-Core transformer. After buying over 50 of these things from James, I am in absolutely no doubt as to the quality of his work, or the performance of the O-Core transformer.
Unfortunately, the maximum VA of an O-Core from James is 300va. That's not enough in this application. Chatting to Angus about it, he had the idea to double them up, like we do in the BT2 and the Avalon. Wiring them up specifically to cancel out the field effect of the opposing transformer. I love this idea and have already got the Traffo request in to James. Here is the Blurb:
O core transformer
The appearance of o core transformer looks like a ring, and the cross section of o core transformer is round, this is different from toroidal transformer. O core has no sharp corners, that means less flux leakage compared to toroidal transformer. The MLT of o core transformer is short and it is copper saving. In some aspect, I think O core transformer has the advantages of both toroidal transformer and R core transformer. An O core transformer can bring dramatic improvement for your audio system.
High efficiency
O core has no cut, no break point, and O core transformer has a round cross section, which reduced the copper length of each turn (low DCR for each turn). So o core transformer has high efficiency.
Low flux leakage
O core transformer is a kind of nearly perfect transformer. The cross section of O core has no sharp corners, it is copper protective and a ring like core can shorten the flux path, which can make the copper wire embrace the core tightly.
Finally, on the first phase of purchases for the new 686, were the Amplifier PCBs.
I don't need to say too much about these, as all the info is easy to find on the Neurochrome Website.
You may notice little red boxes highlighting the new connectors. Tom has moved on from Molex, but I am moving on from any connectors and will have them removed entirely. When the PCBs land, the connections are coming out, and everything will be soldered directly into the PCB.
Tom thinks I am mad, as do countless others I suppose, but I am happy in my world and the thought of those connections makes me sad. They have to go!
This will be the last 686 I build for myself, so I want to get everything done correctly. Then I can just fit it and forget it.
This was the very first amplifier I had owned/heard that eradicated any preconceived notion in regard to valve VS solid state. In fact, to be honest, I wouldn't even know how to classify it in terms of what camp it would sit in, because it doesn't really sit anywhere that I would feel comfortable pigeonholing it.
I've had other amplifiers here. Of course I have! For we are audiophiles, and the thought of settling down with one amplifier for the rest of your listening days causes a slight murmur of doubt in the soul. However, that is what I am doing. Well, in the main lol
Looking at what sort of advances have been made in amplification since I got my first 686, has been disappointing. Hoping to find some new device that tears up the rule book. One that annihilates other amplification! Alas, it appears that whilst there are some setting the "Benchmark" in measurements, nothing really captured my enthusiasm. Purifi are making some fascinating devices too. They are on the cusp of releasing a new higher power PCB. It won't get my money though due to the huge bank of brass headers on the interlinking PCBs. Call it ridiculous, but the old nugget won't knowingly allow brass connections in the system now. Although I may still explore this design at a later date.
Other options were entertained, but my heart was always pulling me towards a new 686 build.
For this build, I wanted a larger chassis. One that could fit more capacitance, Speaker protection PCBS, a soft start PCB and two O-Core Transformers. The O-Cores will not be powering one channel each, but will be powering one phase each. I think that's how Angus explained it, lol.
Here is the case. Purchased from Aliexpress for a very fair price, it should be here in March, lol. Apparently there is a big holiday in Asia which is slowing everything down. :
Next thing I wanted to nail down was the capacitors. I have gone for 8x10000uf, 80v Kemet ALC10 Slit Foils. Here is the blurb:
"Conventional capacitors, being made of large, coiled, thin strips of aluminium, are prone to induce eddy currents across their conducting surface. These currents prevent the capacitor from doing its job optimally, thus degrading subjective sound quality. By introducing a series of tiny slits in the foil conductors, these eddy currents are dramatically reduced, therefore, improving the subjective and measured performance.
Modern electrolytic capacitors are designed for use in power supplies, so most aspects of their design have been optimised. Some advances in the design may not be beneficial in audio applications where the requirements of the capacitors are very different.
Slit foil capacitor research has also indicated that improvements in the general construction of the capacitors give better results in audio where the fidelity of the wave shape is very important. Great attention has been paid to the construction details which can affect the performance, i.e. foil type, its connections and mechanical construction"
I am not sure how much of this is actually true, but the life expectancy of this particular type of cap was a dealbreaker.
For the Transformer, I have stayed with the O-Core transformer. After buying over 50 of these things from James, I am in absolutely no doubt as to the quality of his work, or the performance of the O-Core transformer.
Unfortunately, the maximum VA of an O-Core from James is 300va. That's not enough in this application. Chatting to Angus about it, he had the idea to double them up, like we do in the BT2 and the Avalon. Wiring them up specifically to cancel out the field effect of the opposing transformer. I love this idea and have already got the Traffo request in to James. Here is the Blurb:
O core transformer
The appearance of o core transformer looks like a ring, and the cross section of o core transformer is round, this is different from toroidal transformer. O core has no sharp corners, that means less flux leakage compared to toroidal transformer. The MLT of o core transformer is short and it is copper saving. In some aspect, I think O core transformer has the advantages of both toroidal transformer and R core transformer. An O core transformer can bring dramatic improvement for your audio system.
High efficiency
O core has no cut, no break point, and O core transformer has a round cross section, which reduced the copper length of each turn (low DCR for each turn). So o core transformer has high efficiency.
Low flux leakage
O core transformer is a kind of nearly perfect transformer. The cross section of O core has no sharp corners, it is copper protective and a ring like core can shorten the flux path, which can make the copper wire embrace the core tightly.
Finally, on the first phase of purchases for the new 686, were the Amplifier PCBs.
I don't need to say too much about these, as all the info is easy to find on the Neurochrome Website.
You may notice little red boxes highlighting the new connectors. Tom has moved on from Molex, but I am moving on from any connectors and will have them removed entirely. When the PCBs land, the connections are coming out, and everything will be soldered directly into the PCB.
Tom thinks I am mad, as do countless others I suppose, but I am happy in my world and the thought of those connections makes me sad. They have to go!
This will be the last 686 I build for myself, so I want to get everything done correctly. Then I can just fit it and forget it.
