[Ralph]

Hi, I bought a used RM-9 (original version) in 2004 and would never use any other amp. I would like to upgrade my speaker cable. What would anyone suggest? I have a pair of the original Martin-Logan Sequels being driven by my RM-9.

Ralph John Steinberg

[rbwalt]

Ralph i would look into Cardas cables or JPS. i use Cardas Clear on my speakers( merlins) and my RM9SE amp.


rob.

[Ralph]

Thanks, Rob.

[Ericus Rex]

Welcome to AC and the MR corner Ralph!

I enjoyed my RM-9 using DH Labs Q-10.  My set is not bi-wired.  The thick and thin gauges are connected at each end (whatever you call that - internally bi-wired?).

A friend of mine swears by JPS cables but I've always found them to be very overpriced.  They might do it for you though.

[Chazro]

Here's another vote for DH Labs, great cables for a reasonable price!  I'm running my RM9 into a pair of Spendor S100's that allow for tri-wiring soooo....my bi-wired DH Labs go to the mid range and tweeter and an old set of MIT Music Hose go to the woofers.  My system sings to me every day!;)

[Ralph]

Thank you all for your advice and very warm welcome! My domestic partner gave me the MR amp as a birthday gift back in 04. Interestingly enough, I had first considered purchasing it when I got the Sequels back in 88, and I now wish I had done so (I wound up with a Counterpoint SA 200, not bad, but not in the same class as the RM 9). I am using the 4 ohm tap for the Sequels and have the gain on the RM 9 set at Lo (maximum feedback and damping). As a result, the bloated bass of the cone woofer has completely disappeared and has been replaced by a taut and to my ears deeper bass than before. Praise be to Roger! Anyway, thanks again and I look forward to communicating with you all soon.

Ralph

[Roger A. Modjeski]

DH Labs I good stuff and nice people. I use their wire, coax and connectors in my system and make cables for people who want them.

I'm glad you are enjoying the RM-9. It's a very good amp for driving Electrostatics and the low gain is a good choice as it gets the damping high and keeps the frequency response flat with a speaker that has a large range of impedance. FYI the RM-9 and RM-200 were designed with ESLs in mind as they are the most difficult load to drive. If an amp can drive an ESL is can drive anything. If your amp has the 2 ohm tap give it a try for even more of the above. However, you won't be able to play it as loud, if that is a consideration. One can always use the 2 ohm tap for quiet listening and the higher tap for a party. Impedance taps are an important and usefull thing. I would not want a tube amp without them. I like them so much that I have four impedance taps on the RM-200.

I am a great fan of ESL speakers and have been working on them since 1976. That quest led me to Santa Barbara to work with Harold Beveridge in 1978 where I did quite a bit to improve his direct drive amplifier.  I have recently made some 5000 volt direct drive amps for ESLs of my own design which I will be writing about soon. I just can't stop listening to them long enough to write now.

[rbwalt]

roger i thought that the RM9 when driving a difficult load would have a tendency to over heat it's output tubes. now is that just on the 8 ohm tap when  the load drops to 4 or 2 ohms. also there is a drop in power correct? now what happens on the 4 ohm tap? now i know the 200 and the rm9se are able to put out more power  as the  load impedance drops without overheating their output tubes.

R.

[Roger A. Modjeski]

roger i thought that the RM9 when driving a difficult load would have a tendency to over heat it's output tubes. now is that just on the 8 ohm tap when  the load drops to 4 or 2 ohms. also there is a drop in power correct? now what happens on the 4 ohm tap? now i know the 200 and the rm9se are able to put out more power  as the  load impedance drops without overheating their output tubes.

R.

The particular tap doesn't matter, it's the ratio the speaker impedance drops to in relation to that tap. Anything lower than half the tap impedance starts to overheat the tubes at high power levels. The RM-9 SE and RM-200 use a special driver circuit to allow the tubes to provide extra current and thus more power goes to the load and less to heating the tube. A standard RM-9 does pretty well as it has 4 output tubes per channel which does help.

Remember this: Taps on an output transformer are there so that the tubes see the same load no matter what impedance resistive load is used. In other words the tubes see the same load when an 8 ohm speaker is on the 8 ohm tap as a 4 on the 4 or a 2 on the 2.  This allows the amplifier to put out full power into the matched load. When the load changes with frequency is when we separate the strong amplifiers from the weak.

[Ralph]

Dear Roger:

With the 2-ohm tap and maximum feedback, the sound is not only too low in volume, but sounds rather thin and anemic to me. Plus, when using the lowest impedance tap and lowest feedback, I have blown the output fuses on more than one occasion (no tube or map damage, thankfully). I find the most realistic tonal balance on the 4-ohm tap. As I listen to classical music almost exclusively, from chamber to Wagnerian Opera, I value both healthy dynamics and transparency; with this setting, I get both in abundance. The RM-9 and the Sequels have been recently called into delivering the sound of the greatest of all Beethoven conductors, Wilhelm Furtwaengler, to the ears of all who revere Beethoven. There is a terrific-sounding set on the Audite label of his RIAS recordings with the Berlin Philharmonic, featuring the most harrowingly intense "Eroica" (1952) imaginable. The clarification of musical detail by the RM-9 paired with the Sequels really does bring one into the music, and that is the highest praise for any component.
Ralph

[Ralph]

Dear Roger:

I decided to follow your suggestion to use the 2-ohm taps, while keeping the gain low for maximum feedback and damping. You were right! The sound is even more transparent and the bass tauter, yet deeper. And the volume level is more than adequate. I'm curious:  By how much does the RMS output drop when using the 2-ohm tap?

Ralph

[Roger A. Modjeski]

Dear Roger:

I decided to follow your suggestion to use the 2-ohm taps, while keeping the gain low for maximum feedback and damping. You were right! The sound is even more transparent and the bass tauter, yet deeper. And the volume level is more than adequate. I'm curious:  By how much does the RMS output drop when using the 2-ohm tap?

Ralph

The 2 ohm tap is half the voltage of the 8 ohm tap and thus will put out 1/4 the power or about 30 watts but with much higher current.

I recommend you use the tap that is closest to your speaker minimum impedance as long as you get the volume you desire. Since many listeners are not using the full power of the amp (some are using only a watt) try the lowest tap you have. This is also called "light loading". There is a detailed discussion on that topic, perhaps someone will bump it to the top for us.

So, now you like the 2 ohm tap?

[Ralph]

Dear Roger:

I LOVE the 2-ohm tap! Besides the greater airiness and transparency, I get a more holographic image. Instrumental placement is wonderfully precise. As a matter of fact, the Sequels have a minimum impedance of 2 ohms. So, the match is perfect! By the way, DH Labs do not supply the NYC area with speaker cable; how do you are Kimber Kable?

Ralph

[Ralph]

Sorry, I meant RATE Kimber Kable.

[Ericus Rex]

You can buy DH Labs direct if you don't have a local dealer:

www.silversonic.com

[rbwalt]

i have heard also that DH labs cables are great for the buck. you might look into some of the JPS cables also. kimber is also very good. also check into some of the cardas cables.

rob.

[OzarkTom]

I am a great fan of ESL speakers and have been working on them since 1976. That quest led me to Santa Barbara to work with Harold Beveridge in 1978 where I did quite a bit to improve his direct drive amplifier.  I have recently made some 5000 volt direct drive amps for ESLs of my own design which I will be writing about soon. I just can't stop listening to them long enough to write now.

Huge fan here since 1979. Any of the Acoustats sounded better with the direct drive amps over any other amp. I sure wished someone would bring an ESL out with OTL DD tube amps. Are those days long gone?

[Roger A. Modjeski]

Huge fan here since 1979. Any of the Acoustats sounded better with the direct drive amps over any other amp. I sure wished someone would bring an ESL out with OTL DD tube amps. Are those days long gone?

The prototype Direct Drive amps are working in my soundroom driving the ESL speakers of my design. For those who don't already know, I have developed an ESL that is very room friendly and has a high WAF (wife acceptance factor). They are shown in a post here.

[rbwalt]

roger how about a updated pic of the speakers and amps.


rob.