[hoppy08520]

Hello, if all goes well I will have a RM-9 MK1 soon. I am buying it from a classified (not local) and am planning to have the seller ship the RM-9 to Music Reference for a checkup (although I haven't heard back from Music Reference for 4 or 5 days...hope they are checking email?) and then have Music Reference ship to me.

Looking for a few suggestions on what I should do.

For reference, I have Spendor S100 speakers, an Anthem Amp 1 40 wpc push pull EL34, an Anthem Pre 1 preamp, and I have a 18' x 23' room with speakers along the long wall.  I am not a serial upgrader, having owned the Spendors for 8 years and the Anthem amp and preamp for 9 or 10 years each. I'm hoping I'll hear a difference in the RM-9.

1. If I need new tubes (and I suspect I will; current owner says there are 10 years on the current RAM EL34 tubes), I'm thinking of KT88. I've been using a EL34 amp for 9 years now, so maybe I should mix it up a little?  Ideally I'd like a set of EL34's and KT88's and swap them around every few months or so for variety. I've read some of the other threads and it seems to be a matter of personal taste. I think I'm leaning away from 6550 (based on what I've read) as people seem to characterize these as emphasizing slam/authority and I would lean toward something more musical even I sacrifice some of the bigness the 6550 can deliver.

2. I plan to ask Roger if he can do whatever trick he does to the amp to reinforce the tube sockets so you can roll tubes. There was another thread (http://www.audiocircle.com/index.php?topic=78664) in this Circle in which he suggested he could do this.

3. Speaker binding posts: the speaker cables I have are inexpensive AudioQuest with bananas plugs. Will that work on this amp or do I need smaller spade cables?

4. Based on reading other posts (http://www.audiocircle.com/index.php?topic=89099.0) in this Circle, it looks like Roger can do a partial MK-2 upgrade for the power supply/choke for around $300 extra. Is this worth it? Does this bring the amp's power from 100 wpc up to 125 wpc?

5. I am not necessarily looking for every upgrade as I am sure this is a great amp in its stock configuration and I don't want to spend too much, but is there anything else I might want to consider?

Thanks for any suggestions and thanks to everyone for all the great information in this Circle.

Darryl

[Chazro]

I'm also a proud owner of an RM9 an Spendor S100's!  I bought the S100's new 20yrs ago!  This amp/spkr combo is obviously a winner for me.
 
Re: some of yr questions, the RM9 doesn't accept banana plugs, I guess you could have RM install what you need to be able to use the cables, but for what RM will charge you (and based on your cables) I'd opt for a better set of cables.  I've got a bi-wired set of DH Labs running to the mid and tweeter and an old pair of MIT Music Hose running to the woofer (the spks ARE tri-wireable!).  DH Labs offers very well-reviewed cables on the cheap, you might want to chk 'em out.

Considering the power upgrade, I wouldn't do it.  I'm no engineer, but from what I've read, 25 watts is probably going to be an inaudible difference, especially with the very-easy-to-run Spendors.  I can honestly testify to you that this combo delivers volume, nuance, and slam in a very satisfying way.  Use the money for the bindingpost/power upgrade on a new set of cables!;) 

I'd be interested in hearing yr impressions after you get everything up and running!

[rbwalt]

 i had a RM9MKII and it worked fine for me. i had NOS EL34 Siemens in it for 11yrs with out any problems. that tube is roger's favorite and mine too. it offers the best overall balance. i have them in my RM9SE. I have also heard that the DH labs wire is really good for a expensive wire. you might want to check out some of the JPS labs wire also. i would not do allot tube rolling as it can losen the tube sockets on the circut board and that is a sore point on the amp along with the trim pots. so send it into roger and have him go over it.

rob.

[Roger A. Modjeski]

Hi, I did see "New owner's" email and, as I hoped, those of you who know would provide the correct information, thanks for that. Here is my input.

A point to clarify. The output tube are hardwired, NOT on the circuit board. I wouldn't do that due to heat and stress. You can roll them to your hear's content, though I warn you, indiscriminate tube rolling has a cost of aggravation among other things. If the tubes in the quad are not well matched you are inviting a world of trouble. You can ask rbwalt about this as he has the SE

The driver tubes are on the circuit board and if you want a all hard wired amp get the RM-9 SE. There are NO pcb's in that and the bias pots are on top too. It's the amp to have for tube rollers. I made it for them so they could check every tube, drivers too, in situ with 12 test points per channel.  Besides checking drivers, the output tubes can be measured individual and unmatched tubes can be equalized via a balance control.

On the RM-9 MK I and II, I do not encourage tube rolling for several reasons. When i designed the amp, tube rolling was not popular and I wanted to make an amplifier that was reliable enough to be enjoyed and forgotten. Ten year tube life was unheard of at the time among modern amplifiers.

The front driver has to be selected for less than 3 volts difference in plate voltage as that is the range of the balance pot. If one chooses to use the RM-9 as a tester to select this tube he should rather buy a selected tube from us rather than wear out his sockets. We charge little for the selection and have many types available. See tubeaudiostore.com.

The rear driver tube is non critical and you can just stick anything  you want in there. It won't make a difference. I don't think the type of driver tube makes much of a difference though the gain of the driver tube does make a difference. A higher gain tube will give more damping and lower distortion. We can sell you any gain you want.. Nobody else can because they measure Gm (transconductance) not gain. But then you already know my opinion of those guys and their "Recently calibrated Hickok Tester".

[Ericus Rex]

I've done a little bit of driver rolling and mine and would have to agree with Roger; the differences between drivers were so subtle that I wouldn't recommend risking the sockets for the change.  After several pairs of some expensive NOS tubes I ended up putting pack in the RAM tubes.  All the others introduced unacceptable noise whereas the RAMs were dead silent.  Rolling power tubes delivers substantial sonic differences.  I have Genalex KT88 reissues in mine.

I believe Roger can change the binding posts to accept bananas but agree with the others above that perhaps you should instead invest in better cables (I use DH Labs too!) with spades.

Unfortunately, I've never heard a Mk I with the power supply upgrade so I can't comment.  Why don't you have it done and post your impressions?   

Those 10 year old EL34s are, more than likely, still good since they're original RAM tested/matched.  Go with KT88s if you want a different flavor.  Use the 4 ohm tap, if you can get adequate volume without clipping, and your tubes will last even longer.

Other than 'don't dare roll the drivers!' all I can say about the amp is "Enjoy!"

[hoppy08520]

Thank you everyone for weighing in, I appreciate your insights and reading your posts is seriously making me ache to get this amplifier in my house and playing some music!

re: Tube Rolling: I haven't been a tube roller in my 9 years of having tube amps/preamps, as I don't have the inclination or money to fiddle with tubes (or wires or tweaking my turntable setup or anything else). The only thing I was considering doing with a RM-9 is possibly alternating between two sets of power tubes (EL34 and KT88) every so often. I wouldn't want to mess with the driver tubes.  Seeing as a new octet of power tubes will run me $300 - $500+, I will probably hold off on that for a little while and just enjoy the amp...

re: binding posts. Agree with everyone, I would not want to modify the speaker binging posts. I bought my current speaker cables for $50 and I'm not attached to them, so I'll get some new speaker cables with small spades. Thanks for the suggestions on DH Labs bi-wire, the cost is not exorbitant and I may go with that. I've always wanted to try bi-wired cables on my tri-wireable speakers anyway, so now's the time.

@Chazro: interesting that you have Spendor S100's as well. In fact, what got me started down the Music Reference path was a google search "spendor s100 amplifier" or something like that, and I found at least a couple of people who liked the combo of S100 + RM-9. I don't have any problem with my current amp (Anthem Amp 1) per se, but I've been getting the upgrade itch and I've read that the S100's can benefit from a little more power and all the reviews of the RM-9 were very positive. I'll post an update when I can..

Dear Roger, I do hope I can get my RM-9 in your queue for check-up and the partial MK-2 upgrade, manual, new shipping container (this page http://www.tubeaudiostore.com/rm9maricoled.html suggests you might have some?) and new RAM tubes if needed. Please let me know the shipping address and anything else I need to do.

Thanks again,
Darryl

[rbwalt]

yes i should have mentioned about tube rolling of the driver tubes. doing it to much can losen the tube sockets soldered to the pcb. i know, it happened to me. roger's RM9SE is a very very nice amp. he only built 18 or 19 of them. i do not know how many he has left. the testing of the tubes is simple! the input stage is self balancing and far more stable than the MK1 and 2's. it's sound is much more open,smoother, more dynamic and it is dead quiet.do not get me wrong about the MK1 and 2's they  are good amps but the SE is in a different league. if anyone cares to see one just check out my system under rbwalt.

rob.