Shocked and very saddened to hear of his passing. We were only chatting a few weeks ago but he didn’t mention anything amiss. I’ve known Roger since about 1991 and he has been an inspiration to me ever since. We were always chatting about things like EL84 loadlines, coupling capacitor charge pumping, a good current to run a 6dj8, EI vs toroidal (‘Ugh!’) output transformers, biasing, even automatic biasing, jfet and bipolar linearity, tube noise, etc etc! Having stayed at his in Santa Barbara way back then it was fun to have been driven around in the Jensen Healey and come back to be educated about the tempered tuning of pianos. We had a very close friendship, almost a relationship. He was always keeping an eye on the stock market on a tiny B&W TV. One day we were chatting and he had just received boards for the then new RM200. I sat and looked at it. LM394s for the input stage?, I said, dismayed. He was shocked and a little awed I had worked out the circuit from looking at the unmade circuit board. From then on he didn’t hold back from the engineering aspect of our discussions. Why use heated jfets? he said. One of many discussions about MC headamps. Another... ‘But that’s too much power for the screen grid!’ he retorted, disappointed that I’d neglected to work it out, unfolding a well worn chart of curves for the EL34 he’d made on his computerized valve tester, all written in Basic language. Another year, we went to Borders in SB where he gleefully pulled out a Class A review from Stereophile for the RM200. ‘Yessss!!’, he jolted excitedly. It really meant a lot to him, to be validated for all the hard work that went into it. We had a great time touring the countryside in southern Australia together, and he really considered moving there as he ‘didn’t like the way the US was going’. ‘Those mad Australians!’, a reference from his talk at the Burning Amp 2018 possibly referring to me..? A sad week this week. RIP my friend Roger. I am missing you already.
P.S. I live in the UK now and if you have one of Roger’s amps here I might be able to help service it. I used to service them down under.
Yes I think Roger considered it a mild form of entertainment to check out other maker’s products, ARC a specialty. What he mentioned at Burning Amp 2018 we ranted about years earlier in the 90s! I feel he kept his best work from entering production. The RM-5 preamp was ok but I would give him a go over little things like choice of regulators for the power supply. He would come back with measurements to prove it. (If there’s no noise on it, there’s no noise on it!) But I’m not sure if he ever built his all singing, all dancing preamp that was completely direct coupled from input to output, and used 6 6dj8s. Also loved his direct drive amp for electrostatic speakers, a product of his time at Beveridge. Perhaps the RM9 mod to have a self-balancing driver stage came about as one of our talks? I think he wanted to put auto-bias into an amp as well but didn’t get to having it work the way he wanted. Later he loved Emission Labs tubes for their sheer linearity. He was fascinated people preferred single ended to push pull poweramps, but having built some for himself could see their point. He made a few solid state single ended experiments as well, but they never entered production.
Phew. Bit of a hole in the heart here.
Not that VTLs were much better than ARCs for repairability! Roger was unique in designing circuits that are reliable, something that has stuck with me. David Manley was another of his faves to ‘discuss’. (Translation...be disturbed by.) I always thought using a hybrid circuit with SS input stage on the RM200 he might offend tube purists, but for him the benefits of having a stable input stage with no drift outweighed the perceived but unwarranted sonic shortcomings. But yes I feel the RM9 is the essential Roger at his best, followed by the revelatory RM10 running its EL84s at 700v and all while keeping dissipation within bounds.
I think you mean self bias, not auto bias? Self bias sets the output stage current by circuit configuration with a reduction in output power, and auto bias is fixed bias with a subcircuit to adjust bias automatically. I think he wanted to eliminate misadjustment of the bias setting as not everyone who wants a nice amplifier is familiar with how to do it. Class A operation means lower and more consistent distortion products.
That brings me to a question, what’s going to happen to his vast collection of equipment, and his schematic designs? I’d possibly be able to make sense of the electrostatic tube driver circuit if I saw it again. It’s probably in a cupboard somewhere.
Yes well self bias is the generic term which can also be other forms of self bias as well as cathode bias, like grid self bias. So you’re right, it’s specifically cathode bias. Ok about the schematics. It might be best not to release them publicly as they can be misinterpreted and then erroneously be credited to Roger. Although some are already out there. But if he took care of it, it will be in good hands.
Anyway, Roger has departed! Still a bit in shock.
Yes the RM1! A great design.
Re the nice comments about the RM10: That would have made him very proud. He told me he wanted the RM10 to be remembered as a gutsy little amp. Job done Roger. Job done.
Yes I remember he would say let’s work it out! It annoyed him that people would come out with a statement and say it’s true, and only have erroneous evidence for it.
Mmm, sounds like he was working on the direct drive amp for the Majestic last year. So a circuit for it probably exists somewhere in his stuff. I imagine it would be a refinement of his 80s-90s one. I wonder if this was going to be a statement circuit for him, an early hint that he was becoming ill?
The Quad 57s run 6kV on the two bass panels and specified for 1.5kV on the treble panel. I remember Roger musing that he wanted, I thought at the time somewhat ambitiously, to run 1.8kV on his Quads. I always thought that would be pushing them a bit too far as the classic design is already quite prone to arcing over at higher volume. It was to do with lowering the distortion IIRC.
I’m not that familiar with the Acoustats but have heard them. How did he improve dispersion? Are there multiple tweeter panels on an Acoustat so you can use different phase to each, like on the Quad 63?
It would be brilliant to get Majestics going with direct drive, if you can make it, do! I’m sure Roger would have loved that. (Be very careful with instantly lethal voltage on the tube voltage power supply!!!) You’ll need to have a good working knowledge of their characteristics first, and liasing with Soundlabs would be the way to go I suspect.
Come to think of it, I recall Roger made a special version of the RM9 with 6 input tubes, the extra one being a better driver tube (6BQ7, like the RM200) circuit for the output stage. He also added the self balancing input stage to eliminate needing to adjust it manually, and constructed it with no circuit board. That would be the ultimate amp, and have the best reliability along for the ride! I remember talking with him in the 90s about hard wired construction as being good but labour-intensive to build, and thus expensive. All my own amps have been hard wired to date and it’s good to see Roger did it too! The RM10 is hard wired, a good move.
We have an RM9 Mk2 in the family as well and it’s mostly been reliable but it has suffered the odd quirk over 22 years, and not just tubes. The time the fuse blew at a home audio club event was not only frustrating, it showed the amp to have some physical design flaws, notably the location of the HT fuse underneath, inside the amp. It should be on the top panel somewhere in a safety fuse holder. The input stage and circuit board construction needs updating as well. Roger did know about these things but decided not to keep the RM9 in production, instead opting to make the excellent RM200.It would be good if the RM9 was put back into production, being a powerful all-tube circuit of classic Roger design. He wanted his amps to be as reliable as possible. To that end I’d probably refine and simplify the input stage to have no user adjustments, add automatic output stage biasing (not the same as cathode bias!) to bring it into the 21st century and bring the circuit board construction up to date, to keep his essential design but make it even more reliable. It could be the Mk3 version.
Nice one Jerry.
Clio09, I didn’t know he made the 6L6 version either. When did he do that, and why? If you want to sell it, I’d take good care of it! A bit of Roger in the house would be lovely. I’ve got an idea about how he got 250w out of 6L6s safely. Knowing a few of his circuits, it doesn’t surprise me really.
I wonder what happened to the other 17 RM9 SEs?
Gold! Touching, and I’m glad others who have been close to him have experienced him in a similar way. His amps are destined to become design classics. I agree that the RM-10 is both simple and revolutionary in design.
@bdp24, just the one now :-0
I realise now that Roger’s real family was actually his audience of fans. That must be why he took such good care of them.
It would have been great to be there at the service and hear the stories.
I’m not sure he will quite work things out with David Manley up there though! Is it safe to enter audio heaven with them up there thrashing it out just yet?....