Hand-wired RM9 MK2

Mansky · « **on:** 3 Mar 2013, 08:02 pm »

I am the proud owner of two RM9 MK2's, one for 17 years. Recent circuit board problems have brought the realization that this is the weak link of this classic. I would love to own an SE but cannot afford it at this time. At the risk of sacrilege my question is this: What is the feasibility of hand-wiring a RM9 Mk2?

rbwalt · « **Reply #1 on:** 4 Mar 2013, 04:45 pm »

you probably could get rid of the board but it would be a nightmare to rewire it and not worth it. is yours giving you trouble? the weak points are the driver sockets mounted to the board and the adjustment pots which were not designed for a long service life. think something like a max of 100 rotations for those. suggestion. live with it and do not do any tube rolling with the driver tubes. output tubes are ok for that. do not know why people want to tube roll all the time. the EL34 is the best all around sounding tube for that amp! now i had a mkII for 11 yrs and had trouble with my board just like others. i ended up getting a SE for that reason and a few others. the SE smokes the old MK1 & 2's. sorry guys but it does. the mk1 & 2's are still very good amps but like everything age does play a role. i know roger has 7 SE's left. chat with him about price if you have not done so. you might be able to come to terms. you know your budget. i have sold a few SE's by word of mouth for roger.

you might be able to have a new board made up but again that is going to cost for a one off. good luck!

Ericus Rex · « **Reply #2 on:** 4 Mar 2013, 06:50 pm »

What about selling your two Mk 2s? Could that, and what you have in your wallet right now, get you to the cost of an SE?

I agree with rbwalt; rewiring a Mk2 would be an expensive nightmare!

rbwalt · « **Reply #3 on:** 4 Mar 2013, 07:15 pm »

maybe half way towards a SE. oh yea then you would have to figure out what kind of wire, caps you are going to use. it would still end up being a two driver setup. what makes the SE so special is the 3 driver input( self balancing), the internal wire, caps, type of solder used and the fact that roger wound the transformers himself( they are dead quiet!).`

tubegroove · « **Reply #4 on:** 5 Mar 2013, 02:53 am »

....does the SE actually benefit from the type of solder used?

I am under the impression based on conversations/advice from Roger than generally his designs are not sensitive to "audiophiley" elements like certain power filter capacitors, solder, fuses (that's a particular favorite of Rogers

) etc and that he puts the $$ where it matters like critical signal path caps/resistors , transformers, tubes etc. Wondering if that advice was specific to the RM10 or across all MR designs....

Clio09 · « **Reply #5 on:** 5 Mar 2013, 12:32 pm »

Is this a job you are considering doing yourself or having a competent tech perform? Last year a local customer had board problems with his RM-9 (due to carelessness from excessive tube rolling I might add). So he asked us if we would replace the board with point-to-point wiring. Reluctantly my partner took on the project and was successful in completing the work. So to answer your question it is feasible.

rbwalt · « **Reply #6 on:** 5 Mar 2013, 02:59 pm »

bet is wasn't cheap. i still would buy the SE over rewired MK1 & 2.

parr3n1 · « **Reply #7 on:** 5 Mar 2013, 04:24 pm »

What does Roger suggest doing in this situation? Seems like
he would be the first solution.

Ericus Rex · « **Reply #8 on:** 5 Mar 2013, 05:29 pm »

Roger offers an option where the tube sockets are taken off the PCB and mounted on the top plate. I don't know the cost. You can then roll all you want. I haven't heard that he offers a replacement PCB with more substantial tracings. Maybe if people scream loud enough he'll work on a new board.

rbwalt · « **Reply #9 on:** 5 Mar 2013, 08:06 pm »

yea a new board would be a good idea. it all comes down to $$$ and how much time roger wants to put into a old product( 20+ yrs). do not think it would be worth it for him. also i do not know if those old pots are still available either. i know he cleaned mine out. why would one want to roll the driver tubes anyway? want to make the amp sound better? get rid of that power cord and get it off of its rubber feet.

like i said earlier. getting rid of the board and hand wiring things is going to create its own problems. swapping one for another.

Mansky · « **Reply #10 on:** 6 Mar 2013, 07:51 pm »

Thanks so much for the input, guys. Although I successfully assembled a Heathkit 40+ years ago, I'm quite ignorant on the subject and I'm gratified that my question was deemed reasonable. It doesn't take much to recognize that using a circuit board was a compromise born out of economic expediency. Will soldering a few joints solve the problem or can I expect more deterioration down the road? My understanding is that the RM9 was discontinued because it was too good and is a hell of a bargain. I don't desire to own any other amp(except an SE)and what could I get that would compare? I don't consider myself an audiophile but a lover of music and design. I'm not as concerned with sonic improvements as I am with restoring the structural integrity this otherwise stunning design deserves. I hate half-assed solutions and I don't want a new circuit board. Is it possible to preserve these classics indefinitely, to make them better than new?

I wonder why the tech was reluctant to take on the project. It seems like it would be a fun challenge for the technically inclined. Once you've solved the problem of mounting the tubes and fuses is it very hard to connect everything up? I wonder how many hours it took. Would he consider doing another? I've spoken to Roger a few times over the years and he was very gracious and generous with his time. I think he is understandably less accessible of late and don't want to waste his time with frivolous questions and that's why I'm running it by you guys first. I'd would like to know if he would be interested in offering this upgrade or if he would give his blessing to others. My best friends kid has a electrical engineering degree from the UW and is designing and building tube guitar amps so I might run it by him. I encouraged him to go work for Roger but kids have to do their own thing.

Clio09 · « **Reply #11 on:** 7 Mar 2013, 07:50 am »

Tell me what you consider the problems with replacing the board with point to point wiring are. There were certainly significant hours involved in completing the conversion work. However, if the owner can get another 15 years out of the amp might not that be worth it. The cost of the conversion certainly pales in comparison to a SE version including any negotiated discounts. While the SE might be leaps and bounds better than than either of the previous versions of the RM-9, and I have no reason to believe it isn't, budgets might be the determining factor in the decision.

rbwalt · « **Reply #12 on:** 7 Mar 2013, 03:18 pm »

problems are going to arise when you re-wire. what kind of wire are you going to use, gauge etc? now how is that going work with what was used in other areas of the amp. if you are going to re-wire you best do the whole amp. now changing wire is going to change the sound( roger would disagree) but it will. it is like changing caps. what kind do you use? how is the amp going to sound with them? you can't tell until you do it. not happy then lets try another and another. see where i am going with this? it was built , tested and voiced with what he used many moons ago. you may get it all done and it may sound worse or better. how are you going to know. it is a crap shoot. sure there are people out there that will be happy to take one's money and rewire the amp. like a said it is a crap shoot. make a change here or there and everything gets thrown out of balance.

might be better to pick up a new or used RM200.

i am not in anyway putting anyone down for thinking about do it. just trying to point out the pit falls that may arise.

Ericus Rex · « **Reply #13 on:** 7 Mar 2013, 05:02 pm »

Quote from: Clio09 on 7 Mar 2013, 07:50 am

Tell me what you consider the problems with replacing the board with point to point wiring are.

I think the main problem will be placement of components. I.E. you'll have nothing to solder the components to. The actual distance between stages will require the addition of all sorts of tabs and jumpers and exposed leads everywhere. Now, add to that the fact that the design itself is over the heads of most technicians out there and your tech is bound to run into all sorts of problems. Take a look at the guts of rbwalt's SE:

http://www.audiocircle.com/index.php?action=gallery;area=browse;image=62509

And Roger designed that one to be p-t-p!

Mansky, if you repair the broken tracings, replace the trim pots and don't do any tube rolling you can get years and years of great, reliable sound out of that amp. If you choose to go ahead with the p-t-p conversion I fear you'll end up with a compromised amp...unless you have Roger do the work, of course.

rbwalt · « **Reply #14 on:** 7 Mar 2013, 09:20 pm »

Ericus Rex you hit right on the head of the nail. i agree !00%. as i mentioned earlier put a good power cord on the amp. this can be done by cutting the stock power cord. leave about 6" or so and then just solder on a good EC connector. that is what i had roger do for my amp. i have tried various power cords on it. also get it off of those rubber feet. valid points and pucks work well as do Critical Mass Rize's. do these two things and forget about tube rolling.as a personal preference i would stick with tubes from roger only!! some nice nos siemens el34's really make that amp sing. they are the best from top to bottom. that's it. hope this helps.

rob.

rbwalt · « **Reply #15 on:** 7 Mar 2013, 09:27 pm »

oh yea roger told me that it took him over 50hrs to hand wire each SE and i believe he did them all. he also wound the transformers himself because he could not find anyone that was as good as him. reasons why they cost what they do.

Clio09 · « **Reply #16 on:** 7 Mar 2013, 10:55 pm »

I would agree the project is not for the average tech. I do not consider my business partner to be an average tech and neither do any of his peers in the industry. He is Jack Elliano from Electra-Print who has been around the block a few times and has been known to wind a transformer or two. The work on the RM-9 was masterful and just to make something clear, it was a one off thing and not something we would do again. We are too busy manufacturing our own amps right now.

As an aside Roger sent Jack a note recently complimenting him on an article he wrote for VTV years ago on single ended amp design. I intend to take an example of our upcoming Circlotron amp to Rogers's place for a test spin prior to the Newport show should Roger be available. I am very interested in hearing it on his ESL speakers which I have always admired.

Clio09 · « **Reply #17 on:** 8 Mar 2013, 02:43 am »

Mansky, I just saw your post. The reluctance was due to the fact that my business partner is not really interested in working on repairs or altering others designs. He would prefer to be doing R&D for our own amplifiers one of which can be viewed here:

http://www.electrafidelity.com/silver-45-se/

He ended up doing this for a friend and customer and I might add at no cost. The amp and schematic were provided and as I mentioned in the previous post the work was masterful. Hard to say on the number of hours as he was working on the unit sporadically. Since the intent was not to charge a fee he really didn't track his hours.

Roger A. Modjeski · « **Reply #18 on:** 14 Mar 2013, 06:58 pm »

Quote from: Clio09 on 7 Mar 2013, 10:55 pm

I would agree the project is not for the average tech. I do not consider my business partner to be an average tech and neither do any of his peers in the industry. He is Jack Elliano from Electra-Print who has been around the block a few times and has been known to wind a transformer or two. The work on the RM-9 was masterful and just to make something clear, it was a one off thing and not something we would do again. We are too busy manufacturing our own amps right now.

As an aside Roger sent Jack a note recently complimenting him on an article he wrote for VTV years ago on single ended amp design. I intend to take an example of our upcoming Circlotron amp to Rogers's place for a test spin prior to the Newport show should Roger be available. I am very interested in hearing it on his ESL speakers which I have always admired.

I look forward to hearing the Circlotron on my ESLs. Can you tell us a little about it?

Roger A. Modjeski · « **Reply #19 on:** 14 Mar 2013, 07:37 pm »

Quote from: Mansky on 3 Mar 2013, 08:02 pm

I am the proud owner of two RM9 MK2's, one for 17 years. Recent circuit board problems have brought the realization that this is the weak link of this classic. I would love to own an SE but cannot afford it at this time. At the risk of sacrilege my question is this: What is the feasibility of hand-wiring a RM9 Mk2?

Out of 930 RM-9s out there I have never had to replace a circuit board but for one where the previous owner had "upgraded" all the parts and made a total mess of it. I can sell you a brand new populated board for $850. I am also considering making a hand-wired drop in replacement for $1200 complete. It can be installed here, with full spec check for $400 or by a good tech with minimal instructions. Of course he has to know what he is doing. The new hand wired board can be ordered with balanced input for an additional $200. I will go ahead with it if I get five firm orders with deposits. It will improve the sound and never need replacement. Tube rollers may roll to their hearts content.

Note that Ericus Rex has given you good advice that the board can be saved, I have not lost one yet. I can fix and upgrade the mounting of the driver sockets and go over the amp bringing it up to new spec. typically for $700-900 depending on what I find. The PCB tube sockets are the only weak point and then only if abused.

The choice of the circuit board did allow the amplifier to come at a lower price however that was not the only motivation. Because LEDs and trim pots do not lend themselves to chassis mounting the PCB was the best solution. Hey even ARC at their prices still builds the whole amp on a PCB. You may recall that PC boards were at one time thought to be the best thing since sliced bread. Now we know otherwise. Also keep in mind we are dealing with amps that are approaching 30 years of reliable service... and with original capacitors, so much for re-capping which has become a much sought after and waste of money in many cases. Other than the two 22 uF caps on the PCB all the others are doing fine.