I was contemplating building a linestage based on the ARC Ref 6 or later but I cant find anything anywhere regarding it. Does anyone have any intel? I spent some time trying to decipher pics of the PCB online and it looks like it is similar to the ref 3 but implemented a current sink on the CF along with some regulator upgrades. To be honest it seems like each new iteration from ARC moves closer and closer to Allen Wrights designs but with the 6h30 tubes.
The last 6H30 is a cathode follower, and it looks the same as reference 5. The first two 6H30s may be connected in parallel. From the photo, the cathodes of the two 6H30s are connected together. The color ring of the anode load resistor is not clear, and it seems that two 10K are connected in parallel.
I used Google Translate, can you understand it?
https://tw.my-hiend.com/深不可測的實力-audio-research-ref-6ref-250-se-前後級/
I used Google Translate, can you understand it?
https://tw.my-hiend.com/深不可測的實力-audio-research-ref-6ref-250-se-前後級/
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I think you are right. V2 and V4 cathodes are parallel. I missed that in the other pics I was looking at. It would not make any sense to do any other config with those connected except a CF into a GG which would not make any sense especially with the CS pcb layout being very similar to the Ref 5. It is not like the 6H30 is low on transconductance or anything however I have seen the plate curves of it run at lower voltages and currents. It can run at from 8 ma to 40 ma! I wonder if they chose to run it at low dissipation and double the tube count for some special reason. Thinking about that, I have a VELOCE' LS1 battery line-stage that runs the 6H30's at low current and it sounds wonderful and is highly rated.
I have the REF 3 schematic. It is running at a lower OP and no CS on the CF. It’s interesting that they seem to have moved to lower Operating Points and doubled sections and dropped the current sink on the CF.
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Many years ago, when still young and gullible, i drew up a 3 from pics a member here was kind enough to send me. Perhaps not 100% accurate, certainly not the fet types, nor the actual op points. Built it and mostly hated it. Tried various PSs, including a clone of the original and various volume controls including the DS1666. Hard to believe this has become ARC's one and only preamp topology for all these years...
