[James Romeyn]

I was very satisfied with my sound till I went to John B’s house about a month ago for my second venue auditioning the CDWG on the RM30 (first audition was Brian’s LEDE soundroom).  John had a modified Marantz SACD player, a Bruce Moore tube pre, two Bruce Moore 50W tube monos, & a great sounding vinyl rig.  The sound was among the best I’ve heard.  

The performance was so high that I decided to redo all or part of my system.  I knew one of the enhancements at John B’s was the CDWG, so I intend to get those ASAP.  I ordered a new can of Caig ProGold contact cleaner/enhancer & re-treated all contacts, including AC plugs & wall outlets.  I moved the equipment rack from right of the left speaker to right of the right speaker & behind it.  I got a super thick blanket to better dampen the front of the RPTV between the speakers.  I shorted the contacts of 32 unused phono plugs to short every unused audio input on my preamp-processor, including digital inputs.  (I still intend to short the unused video inputs.)  I moved the speakers up farther away from the front wall & the TV.  This all helped.        

At this point, the immediate & remaining issue was amplification.  John’s tube monoblocks, combined with my sampling some of the best SS amps, revived my previously dead tube fetish.  A tube amp was in my future.

I didn’t have to look farther than my closet to find one.  Out came my early ‘90’s Audio Innovations (long since demised) 25W dual-EL34 integrated amp from jolly ole England.  

At this time, I drove the RM30C’s “fullrange”.  Fullrange is in quotes because the high-pass crossover in the pre-pro is set at 110 Hz, mostly to flatten a huge 90 Hz room mode.  Secondary advantages are to minimize amplifier power requirements & to increase the speaker’s dynamic range & maximum output.  

The upgrade was welcome, but the goosebumps were missing when listening to one CD.  I suspected that might be caused by the tube amp’s far lower power output (25W) vs. my 400W SS amp.  So I decided to passively biamp with the SS on the bass, the tubes on the ribbon array.  I removed the shorting jumper from the RM30C.  My 400W SS amp powered only the dual 6.5” mid-bass drivers.  The tubes now drove only the ribbon array.  Because the tube amp’s level controls provide attenuation to blend with the 6.5’s, I turned the midrange level controls fully clockwise to maximum.  The tweeter level controls were set at about 2:00 PM, figuring this as the approximate setting for proper mid-tweeter blending.  The tube level controls & the speaker’s tweeter control were later fine tuned.  The speaker’s midrange control was left at maximum.    

The above accomplished several goals.  The 6.5’s create back-EMF, have lower sensitivity, & hence are more difficult to drive vs. the ribbons.  The 6.5's are now driven by a high-power high-current SS amp.  Tube power is effectively increased by these three points:

1.   Tubes are now loaded by only the purely resistive ribbons.
2.   Back-EMF from the 6.5’s is transferred from the tubes to the SS amp.  The SS has much higher current for greater woofer control.  
3.   The midrange control is turned fully clockwise to maximum, effectively eliminating it from the circuit.  Tube power is effectively doubled & speed, clarity & transparency are increased.  (The sensitivity of the ribbon array is defined by the three mids, which are 90.5 dB per Brian.  The tweeter has more sensitivity than the mids & requires a pad to blend properly with them.)

The results are great.  I estimate that most of the higher performance still present at John’s is due to the CDWG, his better sources, & the fact that he had about 4’ between his speakers & his TV on the front wall (the TV was soon going to leave).  The fact his tube amp may be better than mine is equalized by the fact that it must power the woofers, while mine does not.  I also plan to move the TV out.  My future room will be LEDE & combine audio & video, but the front projector screen will be retracted when listening to music only.

Readers may recall I had been listening to 2-channel stereo CD’s in ProLogic II.  Since employing all the above upgrades, I re-compared PLII to stereo.  I do miss the side surround channels.  But there is so much more detail, clarity, & transparency in stereo that I now prefer it to the PL II playback mode.  

Amplifiers

My experience is that one of the most common trends in all amplifiers, regardless of type, is: The higher the power, the less pure the overall sound quality.  The problem is the lower the power the less the maximum output & dynamic envelope.  Low power amps sound better, which makes you want to hear more, but you run of juice out sooner; bummer.  Also, of course, the more power the thinner your wallet; ditto bummers.

This is not news to many of you.  You have either personal experience or have read similar reports.  There is the ephemeral “iron fist in a velvet glove”, the amp with both maximum finesse & virtually unlimited power.  But they are rare, elusive, & very expensive.  I would put the $7000pr Parasound JC-1’s in this group, but I still prefer the imaging & upper range performance on far more affordable tubes (more three-dimensional, distinct outlines, vivid, lifelike, musical, palpable, inviting & pleasurable).  The JC-1’s are huge, heavy, heat your room, & will turn your utility meter like a drunk eats nuts.  An unnamed source, one of the most authoritative on this subject, admits certain tube amps, in the treble, beat his (or her) $7000 pair of celebrated high-quality SS amps.

I think the most cost efficient route to practical, high quality amplification for VMPS ribbon monitors is passive biamping.  Get two channels of any decent SS amp to power only the woofers.  Depending on your room size, the amp’s quality, the speaker model, preferred maximum SPL’s, the greatest number of simultaneous listeners, & the bass cutoff of your widest bandwidth software, the power range is 50W-400W.  It is highly unlikely, though slightly possible, that you will have to insert an attenuator or level control in front of this amp to blend with the mids (depending on input sensitivity differences).    

Use a 25W-50W tube amp on the ribbon array.  The tube amps from Asia are crazy-affordable (Jolida, Parts Express, Antique Sound Lab, etc).  Low powered tube amps are inexpensive to re-tube.  If you have any pre-disposition against bottles with glowing filaments in your room, & if the best performance is a goal, I implore & beseech thee to hear your speakers with a decent tube amp before you deny yourslef this delicious, affordable pleasure.  You have no idea how quickly your mind will change, IMO.  If you simply can not repent of your anti-tube bias (pun intended), substitute the best SS amp you can find.  Stay in the 25W-50W range, remembering the earlier rule: Power & purity are inversely related.  It's the same with cars: More power generally means more weight & worse handling/braking.  The Audio Analogue (Puccini?) 60W SS integrated amp I heard a few years ago was very sweet.  There are many other tight integrateds meeting these criteria.  Crank up the speaker midrange control to max.  Set the speaker tweeter control at 1:00 to 2:00.  If this amp has no level controls, we can conquer that problem; PM me.  After your system is razor tuned, the ribbon amp level controls can be replaced with fixed Dale or Vishay resistors.  In all cases, the speaker’s tweeter level control is used to properly blend with the rest of the range.  The speaker’s midrange control stays at maximum clockwise rotation, for maximum output, power, & clarity.                  

If you have an integrated A-V system, you can use two channels of your receiver or multi-channel amp to drive the woofers.  The remaining channels can still be used for the surrounds.      

You can make this work even if you have no preamp & no variable line level (preamp) outputs.  PM me & I’ll explain it.  It will cost less than $20 to fix this.  I’ve done it & it works.  Either amp can be of the integrated type.  You can even use a receiver that has no variable line level outputs.  Trust me you can make it work.  I want you guys to try this out & post your results.  My several decades in audio & working with Brian leads me to believe it is good solid advice.    

My Favorite Non-existent Amps

I think an amp like this is about as close to perfect as you could get for any passive-biamp speaker.  It will probably never exist unless you build it.  There would be a sum total of two channels on one chassis, though it could never be called or used as a “stereo” amp.  Two of these dual-channel amps are required for stereo, but it's too strange & misleading to call it a monobloc.  A small, light, cool running, high-sensitivity 200W into 8-Ohm SS amp would drive the bass drivers.  This SS amp will have an input level control to blend with the following high-range amp: The second amp channel would be a dual-KT88 tube amp, about 50W, to drive the upper range.  This channel would have no level control for highest purity & performance.  Both the SS & tube amp are side by side on one chassis, for easy placement directly behind or next to each speaker.    

For triamp speakers (currently no VMPS are triampable) the preferred amp would be similar to above, but the 50W tube amp would drive the midrange only.  An additional third channel amp would be a very sweet, incredibly delicate 11W SET (probably 300B) tube amp driving high-sensitivity treble driver(s).  The speaker must have 6 dB more treble sensitivity vs. its midrange.  Depending on which caused less distortion, a level control would be present on either the mid or treble amp.  All three amps are on one chassis, for easy placement directly behind or next to each speaker.      

(For those interested in triamping: This generally requires a robust high-current variable line source to drive three amplifiers.  You can make it work, though, even if you do not have such a preamp; PM me if interested.  Two of my friends build tube amps.  One is an Asian engineer who designs & builds them in his sleep.  He sometimes uses schematics & parts from Asia, where tubes may be more common than transistors in high end audio.  The other friend just loves to build tubes, & has built maybe 20 or 30 by now.  Of his many amps I had the pleasure to hear, one was a 300B SET with about 11W.  My tube amp is very good.  His 300B handily beat mine in the midrange & more so in the treble.  Cymbals & instrument overtones reproduced by it were insane, other worldly.  Still to this day I’ve never heard anything like it in the treble.  Maybe this level of treble performance does not exist in SS.  It clipped driving the ribbon mids & tweeters.  But 11W driving a 96 dB tweeter would equal the output of a 50W amp driving 90 dB mids.  If I was going all-out, hog-wild, no second best, I’d triamp with something like my friend’s 300B driving only the 96 dB tweeter.  Shoot, I'd use that exact amp & call it a day!
         
That’s my story & I’m sticking to it.

Merry Christmas & a happy new year to all.

[woodsyi]

Jim,

I got a pair of modified ASL monos for ribbons and a pair of eAR 1k watters for woofers.  Not in one chasis but sitting right next each other next to the speakers. After trying passive biamping I went active and like it even better.     I have toyed with triamping but didn't want to mess with blending the tweets and mids -- I like it the way it is.  120 watts more than compensate for the inefficiency.  I have, however, high passed the woofers and added a pair of Largers to do the grunt work -- tighter mid/upper bass on the woofers.  And this is on the 40s.  You might want to look into adding a pair of Largers to the 30's, unless of course you add 4 like John. Happy tube rolling!

[Skynyrd]

Great in-depth post Jim!

I tend to hear changes for the better when actively (discontinued Madisound "Sledgehammer" X-over) bi- and tri- amping my various systems as well.  And I don't use components anywhere near in the league as you and Woodsyi.  I have better, deeper bass in my room when I actively bandpass the midwoofers of my RM40's at around 80hz (low end) and 280hz high end.   Then I use a couple of NHT1259 woofers for 80 hz and below in big boxes that my wife knows will stay until she can find something else that performs as well.  In her words,  "You like them because they punch."

The RM40/NHT system does a good job of performing as well, and usually better than the Magnepan MMG/NHT combo.  Not ten times better, as the price difference between the speakers would indicate, though.  Tough to beat those $550 MMG's for the price.  Easy recommendation due to their cost!  Thanks to Jim Winey for making audiophilia affordable to the working class (and below)!

I've only used a couple of Heathkit monoblocks (WM-4 I think) for tube amplifiers.  I never heard any tube "magic" with those amplifiers ever.  Even across different speakers and with different pre-amps, etc.  They aren't missed--sold them to a friend, though.

  I'm charged reading about $179 Behringer power amps available at Parts Express--so I known when my Adcom gives up the ghost, I have options instead of the repair shop or a high-end purchase that I can't/won't attain.  That Adcom 5300 drives the snot out of those "megawoofers"   , if only for a couple hundred hertz!!

The RM40 mids/tweet get driven by a AVA Dynaco 120 rebuild.
The NHT1259's get driven by an AVA Omega3 Hafler220 chassis.
Adcom 5300 pushing the "megawoofers" .


Wait.  Come to think of it, I never let the Adcom drive the NHT woofers.  Tried that a time or two and I won't go back.  Although, if someone switched the AVA Omega3 and the Adcom without me knowing, I truly wonder if I'd be able to tell!?!

Ain't a fancy cable in the place, and I've got a lotta cables!

Merry Christmas and Happy Listening!

Skynyrd"I like Lutefisk"

[Marbles]

Jim, to get close to what you want, you could use an electronic XO, a Crown K2 amp for the bottom and your choice of tube amps for the mids/tweets.

If I were to demo tube amps, I'd probably start with the Dodd 120's.

I've heard these amps on Epiphany 20/21's driving them full range (down to the mid 30's) and I liked what I heard.

http://www.crownaudio.com/amp_htm/k.htm

The Crown's are under $1K used and have a transferable 3 year warranty..they are bullitproof, sealed and have no fans.

http://www.doddaudio.biz/

[James Romeyn]

Thanks to all for contributing!

I should emphasize there certainly are crummy tube amps I'd never recommend.  Older Heathkits may be in that camp.  But I've heard & been very impressed by recent, affordable tubes from Jolida & ASL.  Regarding my tube amp: Brian bought it from the original USA distributor.  He had a funny name, the "Audio Valet", I think.  It was originally about $1600 MSRP.  Some of you might remember Neil Levinson, the high-end editor from Fanfare magazine years ago.  He had in-depth experience with the best amps.  He may be the one who introduced the importer to Brian.  He heard this particular model & bought one.  All the amatuer reviewers agree it is a special amp.  NHT was the importer for awhile before the manufacturer disolved.  It's the best amp this small company made.  Some minor reliability issues, but simple, straightfoward RCA circuitry, & I've got all the schematics (a little tight to work on).  The MM phono stage is one of the best anywhere.  I'd estimate used value between $300-$500.  Owners may be disinterested in sellling, because what would replace it?      

Because the TV eliminated much of the space, the VMPS Larger (w/ PE amp, the one I recommended to Brian 1.5 years before he tried it) would not fit.  I'm using a super compact sub from a different manufacturer, w/ twenty-seven-hundred WRMS, closer in sound to the VMPS Larger than anything else I've heard.  

The single-band EQ in Brian's amp performs well in this room, because it must flatten only one mode at 30 Hz.  (The broader mode centered at 80 Hz is flattened by low-pass crossing the sub around 65 Hz & high-pass crossing the mains around 110 Hz via the pre-pro.)  Left unattended, this room's two huge mods make high-end sound impossible.  The above tricks provide almost perfectly smooth bass response.

If you count the sub & it's amp, I'm triamping now.  The combination of the sub & high-pass crossing the mains provides stellar, superlative punch & impact in the mid-bass & crossover range to the ribbons.  The difference in the tonality & transients of every bass instrument is much more emphasized.  This range now equals the performance of the ribbons.  The performance is adequate in this range without these upgrades, but I could never go back now.  I don't think it's possible to get this level of bass performance without these upgrades, & the posts from others who have tried it, as stated above, seem to agree to a person.  As I've mentioned to Brian, the impact & dynamic envelope of the entire system reaches a completely different level.  As owner's know, it's very good in this area even without these upgrades.  The bonus is that high-pass crossing the mains seems to increase the performance in the entire ribbon array.

Overall, the recent improvements increase performance in interesting ways.  Individual musical lines & themes are far easier to follow & understand the author's musical intent.  Instruments & images float in a more perfectly defined space, yet when they appear & disappear they are less distracting than before.  You kind of just say to yourself, "Oh, that was nice"  The musical intent is far more clear, more enjoyable, more easily & immediately defined.  But the musical whole is enhanced, not diminished.  And listener fatigue is virtually non-existent.  You hear sounds that were not noticed before.  For instance, before a strummed electric guitar was just filling in with undefined noise, now you hear & picture his specific strumming technique (maybe being a guitarist helps).  You hear exactly when he starts & fades out, & his space in the soundscape is well defined, his reason for being is clear, & you like it.

[meilankev]

Jim,

I've been running the RM40s with tube monoblocks for over 3 1/2 years now.  Oh, I've tried out some mega-buck Solid State brutes during that time, but I still prefer the tubes.  The ribbon panels are ultra-fast, and I feel the sound is more balanced when fed their signal through a tube power amp (or monoblocks).

I also biamped for 2 weeks at one point, but found very little improvements over running the tubes full-range.  Granted, most tube amps will not have the oomph to pull this off, and therefore, the owner might find more to like when biamping.  But for me, I'm a happy camper.

Also note I use a tube stereo preamp, and 95% of my listening is vinyl.

I can't imagine any VMPS owner any more satisfied than I am.  My upgrade plan will not kick into gear for another decade or so.

Kevin

[James Romeyn]

A couple days ago I heard the $4000pr Nola Elites driven by current model ASL 200W pentode monoblocs, $5000 MSRP/pair.  It would be very very interesting to hear those amps drive any VMPS Ribbon Monitor.  I think bone stock RM30's would smoke the Elites, BTW, but everyone knows my ribbon bias.  The RM30-CDWG would just be in another universe vs. the Elites.  Re. the Elite cabinets: Surprisingly underwhelming.  IMO any normal RM30 cabinet is finished to a higher standard.  The Elite's oak edge veneer & sharp corners look pretty darn mediocre & are not up to high end standards.  (I'm told Carl's business partner caused Carl to leave the company, that the partner was the carpenter, & it shows.)  In this case, the Elites looked home-built, not the VMPS.  My opinion only, worth exactly what you paid for it.  I like the Elite's bass from dual 8's in seperate sealed subenclosures.  And center imaging was darn good, especially with the huge equipment rack between the speakers.  But speed, detail, transparency & resolution, RM30 wins, hands down.    

I'm stuffed, how are you guys doing?  Time to watch & listen to some new gift software...

[woodsyi]

A couple days ago I heard the $4000pr Nola Elites driven by current model ASL 200W pentode monoblocs, $5000 MSRP/pair.  It would be very very interesting to hear those amps drive any VMPS Ribbon Monitor.

I have a few people coming over later today to listen to the CDWG RM40s, the ribbons of which are driven by Response Audio modified ASL Hurricanes.  I think they are very, very good with VMPS ribbons in triode.  I will try to flip it to pentode and see how others like it.  I prefer the triode (120watts) over pentode (200watts).

[mca]

If I were to have my choice of Butler tube amps to drive my RM30’s what would be the better choice?

Single TDB2250 driving the RM30s full range at 400 wpc.

Single TDB5150 biamping the RM30s with 225 wpc into the woofers and 225 wpc into the mids and tweets. Is that overboard for the mids and tweets?

[James Romeyn]

250W is OK for the ribbons.  The rule still applies that most people cause damage by underpowering, not overpowering.  Definitely biamping will be better in quality, possibly also in quantity (maximum SPL).  I know of no downside to biamping & no advantage to the single 400W amp.  

The waveguides require a bit more level from the mids & treble.  My biamp experience is that you will probably have the midrange level controlls turned up near max & the tweeter control around 2-3 o'clock.  This works out well, delivering almost all the amp's power to the ribbons.  

If vertically biamping, you could possibly short the amp's L-R internal inputs together to allow only one interconnect per amp (must check with manufacturer; shorting the inputs of a fully balanced amp with floating grounds could cause a serious breakage, but most amps do not meet this specification).

Call me if I can help in any other way.

[JoshK]

I think if you are going to go tubes, you should skip pentodes altogether (although admittingly there are some good triode strapped pentode amps) and go DHT, either SET, PSE or PP.  Both from the distortion perspective and the transfer curves, the triodes have a je ne sais quio. Good triode amps are $$$ which is why DIY is a great thing, but not for everyone.  

Modern Chinese tube amp designs typically are 2 stage and put a super heavy burden on the input/driver tube, which are one in the same in this topology, worse even when the amp is PP, as it plays phase splitter duties too.  In this type of amp, the driver tube make 95% of the character of the amp.  Keep the cheap output tubes and roll the driver to taste.  You can get a long way towards an uber tube amp by the right choice of driver tube in an inexpensive design.

HTHs,
Josh