Summit's midrange

[roberto]

i can understand where you're coming from. my experience with the vantages haven't lead me to conclude they are a "poor design", but for me, it took a change in amps in order to achieve what i was looking for. call it synergy if you want, but the vantages, specifically in the midrange, sounded significantly better with a lower watt, 0 feedback design. that's just my experience, and it's all i can share. i thought it might be useful. we all make our own choices. if trying a different amp doesn't seem reasonable to you, and selling the summits and trading them in for some meadowlarks or something else makes sense, then go for it. these are personal choices, we all have our own priorities, and we all hear something different, so what's right for me is most likely not right for you. again, i felt like i had a similar experience in hearing an anemic midrange, and i was able to resolve it with my vantages, i figured you might be interested in what i had to say. good luck and let us know what you end up doing.

Hola...I agreed with you in many things, like small amplifiers are better sounding than the big ones...and with this new type of stat panels, with a sensitivity of 92 [email protected]/m allow us to have the chance to use these great small in power, super sounding amplifiers, and they can be tubed or SS. The design of SS driving low impedance is a difficult task, but not impossible, and we all know that out there are some good hi-end good brands that uses ML as a "tool desing", due to this low impedance. Just to name a few on SS, Blue Circle, Bryston, Classe, ARC (SS), Conrad Johnson (SS), Krell, Aragon, Sunfire, Carver (Bob), Mark Levinson, Jeff Rowland, Audio Analogue, Spectral, Pass Labs, AF, Bell Canto and many more that I can´t recall now...on the other hand, we have tube amps. The tubes have a very high impedance and we need the help of a transformer to couple this typically 5000 ohms to our speakers that are very low 4 ohms, and with ML, we know that at 20KHz sometimes we have less than 1 ohm! High quality transformers are used in most hi-end tube amps, and they can drive this low impedance without any problem. We, the tube users, what we like over the SS sound is the mid range...and at this particular frequency range is where the most music and all musical instruments perform. We say that the tube is sweeter than others, and we know that it is due to the "even distortion" and our ears can not detect this kind of distortion easely. The stat panels of ML reflect all this due to the lack of distortion. The diaphragm is so light, that weights less than the air that it moves!!! One of the stronguest feature of the stat panel is this unmatched transparency, that reveals any kind of electronic component that we have in our system. What Mr. Dbakker didn´t like on his new Summits, and having previously Prodigy, is at the lower mid-range region. He is missing a resonance on his system that was better for his ears and liking than his new Summits, and he is trying to get this "same sense" of the cello at his system as was before with the Prodigies. Of course Mr. Dbakker is aware of the improved difference of the Summits versus the Prodigies. Perhpas with high quality single crystal copper cable might work, as an example harmonic Tech...I was told by my ML seller, that one of the stronguest points on the Summits is that the panel is complete 100% free like the CLSs. On the hybrid models, the used panel (dipolar) is only 80%. Part of the stat panel is not dipolar, because of the speaker´s cabinet. Well, I think that everything is a matter of liking. Trust you ears, and keep what you like most, regarless of specifications. Your ears are the best and not match tool available. Some of us, like the sound forward and present, others we like it different, but what we like most is the transparency, distortion free, size of the isntruments, air between them and the scenario that ML is capable to produce. Happy listening,
Pura vida,
Roberto.

 

[aliveatfive]

Well said, Roberto. I think you're absolutely right.

 

[AlanW]

Thanks for the posts on tilting the speakers forward. I purchased a pair of Ascents last weekend and the imaging and soundstage was not quite focused. After tilting them forward it came together and made a huge difference with my system.

 

[AudioFanKJ]

Again, I think I need to emphasize this was not a personal attack at all, nor an attack on the Summits. Please accept my sincere apologies. I will also state I do not think the Summits are "flawed"... that would be too strong a word, even if they remained sounding as they do now. Likely the sonics will change with break in as well as positioning and set up. However, if it does sound like this, I would state the voicing doesn't seem to have enough body in the midrange. Again this is all speculation.

I will be the first to admit amplifiers and associated equipment and cabling makes an enormous difference. Amps I have owned include the Sonic Frontiers SFS-80, Sonic Frontiers SFM-160, Music Reference RM-9, McCormack DNA-1 Dlx... (all of these listed were used with ML SL3's as well), also owned the McCormack DNA-2 Dlx, Cary SLM-100's, Unison Research Unico integrated, Bryston 4B, Quicksilver V4 monoblocks, as well as my current H2o Signature Monoblocks. Those amps I have owned and had in my home. I have also in home auditioned Ayre, BAT, Rowland, and I am certain others that don't come to mind at this time. I state this, as I know, there are definate sonic differences between tubes and solid state. There are also VAST sonic differences between tubed amps, such as Audio Research versus say a Cary. Just as there are VAST sonic differences in solid state say a Bryston or Krell versus the sonic flavor of a Rowland or Ayre.

The reason I am honestly quite bummed at this time with the recessed midrange of the Summits, is the amps I know own are the absolute first amp that I have owned that is NOT a tube amp, and not sell nor wish I had tubes. Most solid state amps would last a few months at best in my system. Then I would HAVE to go back to tubes. THere is just something magic in the midrange presentation of tubes. Some argue it is the distortion, or the type of distortion per say. Tubes are said to emit an odd order harmonic distortion, which to the human ear sounds like something being slightly out of tune. Solid State I was told emit even order harmonic distortion, which sound more along the lines of hiss and are more offensive aurally. (I think I have the odd/even correct here - I am no expert, but have heard this more than once, so perhaps it makes sense). As even live instruments slightly out of tune are still music...

With that being said the H2o Audio Monoblocks are a switching amp that is mated with an analog power supply. I think this is one of a kind or only one of a handful that are spending the expense of a killer analog power supply on the ICE based modules. These amps were designed, created, and built by Henry Ho, whom has been building deep cycle class A amps for well over a decade. He builds his amps around the ability to drive his Apogee Scintilla's. In which I heard when I went to audition these amps. Incredible speaker.
Anyhow, a long post a bit shorter, what I heard was suprising to my ears, control of the bottom end of a Krell, yet the liquidity and palpability and presence in the mids of tubes, and a crystalline top end of very high quality tube amp, absolutely grain free.

Thus I have found an amp that provides the glory of a tube amp, yet, with the power and control that tube amps I have owned can not come close to comparing with. For any interested in another blurb on the amps I own, which are not that common, here is a link:

H2o Audio Signature Monoblocks Review

Again, I hope my dismay is premature, as I only had about 200 hours on them when I left town, and tonight they should have close to 300 hours on them when I return home. I was planning on silence of opinion until they had a good month to break in, but felt it was just too coincidental that others seemed to be hearing the same recessed midrange and/or lack of body/substance in the midrange as me...

 

[roberto]

Again, I think I need to emphasize this was not a personal attack at all, nor an attack on the Summits. Please accept my sincere apologies. I will also state I do not think the Summits are "flawed"... that would be too strong a word, even if they remained sounding as they do now. Likely the sonics will change with break in as well as positioning and set up. However, if it does sound like this, I would state the voicing doesn't seem to have enough body in the midrange. Again this is all speculation.

I will be the first to admit amplifiers and associated equipment and cabling makes an enormous difference. Amps I have owned include the Sonic Frontiers SFS-80, Sonic Frontiers SFM-160, Music Reference RM-9, McCormack DNA-1 Dlx... (all of these listed were used with ML SL3's as well), also owned the McCormack DNA-2 Dlx, Cary SLM-100's, Unison Research Unico integrated, Bryston 4B, Quicksilver V4 monoblocks, as well as my current H2o Signature Monoblocks. Those amps I have owned and had in my home. I have also in home auditioned Ayre, BAT, Rowland, and I am certain others that don't come to mind at this time. I state this, as I know, there are definate sonic differences between tubes and solid state. There are also VAST sonic differences between tubed amps, such as Audio Research versus say a Cary. Just as there are VAST sonic differences in solid state say a Bryston or Krell versus the sonic flavor of a Rowland or Ayre.

The reason I am honestly quite bummed at this time with the recessed midrange of the Summits, is the amps I know own are the absolute first amp that I have owned that is NOT a tube amp, and not sell nor wish I had tubes. Most solid state amps would last a few months at best in my system. Then I would HAVE to go back to tubes. THere is just something magic in the midrange presentation of tubes. Some argue it is the distortion, or the type of distortion per say. Tubes are said to emit an odd order harmonic distortion, which to the human ear sounds like something being slightly out of tune. Solid State I was told emit even order harmonic distortion, which sound more along the lines of hiss and are more offensive aurally. (I think I have the odd/even correct here - I am no expert, but have heard this more than once, so perhaps it makes sense). As even live instruments slightly out of tune are still music...

With that being said the H2o Audio Monoblocks are a switching amp that is mated with an analog power supply. I think this is one of a kind or only one of a handful that are spending the expense of a killer analog power supply on the ICE based modules. These amps were designed, created, and built by Henry Ho, whom has been building deep cycle class A amps for well over a decade. He builds his amps around the ability to drive his Apogee Scintilla's. In which I heard when I went to audition these amps. Incredible speaker.
Anyhow, a long post a bit shorter, what I heard was suprising to my ears, control of the bottom end of a Krell, yet the liquidity and palpability and presence in the mids of tubes, and a crystalline top end of very high quality tube amp, absolutely grain free.

Thus I have found an amp that provides the glory of a tube amp, yet, with the power and control that tube amps I have owned can not come close to comparing with. For any interested in another blurb on the amps I own, which are not that common, here is a link:

H2o Audio Signature Monoblocks Review

Again, I hope my dismay is premature, as I only had about 200 hours on them when I left town, and tonight they should have close to 300 hours on them when I return home. I was planning on silence of opinion until they had a good month to break in, but felt it was just too coincidental that others seemed to be hearing the same recessed midrange and/or lack of body/substance in the midrange as me...

Hola...just a litlle correction regarding the distortion...if you take any specs of a tube amp, you will find that their harmonic distortion is refered below 1% THD...why this number is sooooo high if you compare it to SS? (SS typical is 0.03 TDH or less in a high end amp)...it is because the distortion is even, not odd. Transistors produce odd distortion that your ears detect it very easy. The even distortion is what makes anything sound like it, your voice, my voice, a guitar, a piano, any musical instrument, and if we reproduce this even distortions, then we get close to the real thing. Also due to this too much distortion on tubes, the sound could be too warm, too much, loosing the right size and air of the musical instruments or voices. By your experience, you do know all this, and also using cables as tone controls. We do know also, that silver is great for highs, and cooper is great for bass and lower mid range...perhaps playing with this, you could get again your cello back there in your room. Your new Summits have a lot of little things that makes them unique. They are more fun to use, and more precise in overall harmonic extructure. Perhaps you need more time with them to get used to their sound and body of the instruments. They produced in my room a sense of there are no speakers here...just a musicians playing for me...the heart and the little magic of any instrument was there...to my ears so far, I have not heard anything like them for the price tag that you pay, and these are 10 grand pair of speakers...not low price...the new topology of the new stat panel is so evident, that we are now capable to use this all great sounding amps that are out there, that are kind of small in power, but unmatched in sound quality...don't worry about this lost of feeling and body that you are missing from your Prodigies, there are so many new good things, not only the extension on both ends, just great sound...easy to tune the bass response of any room, and the image is one of the best available...happy listening,
Pura vida,
Roberto.

 

[AudioFanKJ]

Roberto,

Thanks for the clarification on the odd/even order harmonic distortion! I knew I would mix them up...

I think you may have another person and I confused a bit... I think it was someone else that had mentioned the cello with perhaps their prodigy's...

I was just commenting on the recessed midrange. However, I may have been a bit premature. I am still going through break in, and currently have about 320 hours on them. They do sound quite a bit better at this point than when I left last week.

Yes, cables can definately affect the sonic signature, that is for certain. The Purist Audio cabling should be very extended, and just a bit on the warm side of neutral if not completely neutral.

At this point I think I am just going to continue letting them play for another couple hundred of hours, and then will tweak placement, rake of the stat panel, and then the bass controls. I would imagine this will only help dial everything in.

Will keep all posted. What I can tell others is I do think there has been some midrange development between the 200 and 300 or so hour mark.

 

[attyonline]

Really appreciated the advice regarding tilting the Logans forward with the rear spikes. Kind of like focusing a good 35 mm camera. When its right, it gets spooky good!

 

[jjqiv]

With all due respect Steve, a speaker should be created to work well with any quality amp. One should not have to go to SET amps to get the midrange to perform as it has in the past. Whether there is better top end extension, bottom end integration and such is all just "swell"... however, all of it is realisticly useless without a believable midrange. That is where the magic must be.

I am hoping this is still part of the break in anomaly... however I don't think any great speaker, Martin Logan or otherwise, should have to rely on a certain type of amp. That is just poor design if that were the case.

Please don't get me wrong, I am well aware there is often times a great "synergy" amongst certain components, specifically amp/speaker combo... however the said speaker should also perform extremely well with extremely good gear. It should excel beyond that with that certain "synergy"... but at least should sound great with good gear, and not require a certain sonic signature SET amp to sound as it should...

*my two cents*

I'll raise your two cents!

So you are saying that Martin Logan should design their high-end speakers so they will not reveal the sonic nature of amp, pre, source, etc.? If they do that, then they are no longer a high-end speaker. High-end speakers, Logan's or not, really start revealing the wheat from the chaf.

 

[AudioFanKJ]

jjgiv- well, no, not exactly. Perhaps I was asking for trouble not waxing lyrical about the ML in a ML owners forum.

It should do just what you said, reveal all upstream components honestly & faithfully.

However, I had entertained another local audiophile today for about 4 hours and we played with placement, bass settings, etc. The Summits only have 350 hours on them so far, but they did not compare in any way to the Meadowlark Blue Heron 2's I had prior to them. The phrase that was said that sums it up is, "the Blue Heron 2's sounded more like electrostats than the Summits do"...

Again, I hope there is break in yet to come. The dynamics do not compare. The highs aren't as smooth. The midrange is not as textured or organic. The inner detail was perhaps almost on par. Perhaps that isn't the Summit. Perhaps the Summit's high frequency range won't compete with the ScanSpeak Revelator tweeter? The BH2's also had the ScanSpeak Revelator midrange, not to mention the dual 8" woofers, in a time and phase aligned, first order crossover, transmission line enclosure. The BH2's also retailed for a couple thousand more, so they are technically not the same price point. BUT I would think the Summits should be at least close in performance.

What I was trying to state is just what was stated prior to this post. Speakers are supposed to show what it is being fed, ruthlessly revealing if need be. The BH2's have done that, and as other speakers worked beautifully with the components I am running. Others here in this forum have also stated the lack of midrange "presence"... perhaps all of our speakers just need to break in? The manual states 150 hours?

Whom has a pair of Summits that they feel are completely broken in, and how many hours did you think they required to reach this point?

Thanks for the help. I OWN the Summits, trust me, I WANT them to work, hell work well. I want them to outperform what else has been in the system.

Still somewhat dissapointed and tweaking...

 

[Steve Daigneault]

jjgiv- well, no, not exactly. Perhaps I was asking for trouble not waxing lyrical about the ML in a ML owners forum.

yeh, you kind of were asking for it!

However, I had entertained another local audiophile today for about 4 hours and we played with placement, bass settings, etc. The Summits only have 350 hours on them so far, but they did not compare in any way to the Meadowlark Blue Heron 2's I had prior to them. The phrase that was said that sums it up is, "the Blue Heron 2's sounded more like electrostats than the Summits do"...

you know something's not right when box speakers with cones sound more like electrostats than an electrostat!

i stand by my assessment that these speakers aren't going to sound their best unless paired with tube amps, and even among tube amps, there are better choices than others.

you tried various amps w/ your meadowlarks, so the H20 was a "mature" amp decision, it was based on several auditions, and was the winner after comparison. i'm afraid that the summits aren't meadowlarks, and so won't react to your upstream components in the same wonderful way the blue herons did.

it reminds me of when i purchased some Harbeth M30s for a friend. we hooked them up to my system, which had been tuned perfectly for my Martin Logan aerius is, and when we hooked up the harbeths, they sounded awful. SLLLLOW, congested, muddy. this is *not* the reputation they had, and i was surprised! my electronics were top notch, a VAC renaissance preamp and renaissance 70/70 amp, with a teres turntable, basis vector tonearm and a shelter 501mk2 cart.

we then took the harbeths to his place, hooked them up to his dinky rotel integrated and sony cd player, and they sounded great. in my experience, the harbeths come alive when paired with solid state gear.

all martin logans in my mind are ultra-transparent, and are definitely lean. from what i've heard of meadowlarks, they are not lean at all, in fact, are probably warmish. great big sound, wonderful tone, but they do better with faster electronics. which is the opposite of what your summitts need.

no rights or wrongs here, it's just that your system isn't designed to sound best with the summitts. it's been, through trial and error, built to sound best with your meadowlarks...

 

[robertawillisjr]

For my Quests the best amp in my room is a Mark Levinson 335. I've heard the Summit with the newer Levinson amps and they sound pretty good. Good enough to get the dealer to set them up (optimally) in his room next week for an audition.

 

[Craig]

no rights or wrongs here, it's just that your system isn't designed to sound best with the summitts. it's been, through trial and error, built to sound best with your meadowlarks...

Symmetry is the result of all the components complimenting each other. There is no antonym for the word synergy so I don't know what to say is happening here but it certainly isn't synergy.

The Summits work well with more amps than previous MLs but even the Summits don't work with all amplifiers. I recently tried a brand new Cary A-306 600w digital amp with my Summmits. Some strange things were going on between these 2 components and just would not work with each other no matter what I tried. Both the Amp and the Summits were fine and nothing was wrong with either piece. The amp worked fine when connected to Ascents and the Summits were fine with any other amp.

Maybe there is something not so good going-on between internally powered (ICE power?) Summits and ICE power amplifiers? Whatever the antonym for the word "synergy" applies in these cases. Hmmmm?

I think you need to try a couple of other amps with your Summits and then see what happens. While the Summits opens up the number of amp possibilities you can use I don't think the Summits will work optimally with all amps. high-end or not. I also think there are speakers that may sound better in certain systems than a pair of Summits would in that same system because of the synergy factor.

 

[AudioFanKJ]

Steve & Craig,

I totally agree with both of you. It is really an accomplishment to finally get to the point of the entire system sounding great as one unit. In hindsight, I really didn't think of how my amps would do with the Summits. I know my amps did incredible with the Apogee Scintilla's, however all speakers are created different. I am still not holding out hope that more break in will continue to happen. I am also going to experiment with different power cords (as they were already on the way)... then I will work with toe in, rake of the stat panel, and placement after break in. If all of the above don't end up in sonic nirvana... then perhaps a friends Manley Stingray integrated may have to make a visit, with his permission... Just to get an idea, and a baseline between the two.

It is just good to know that there are those out there with the Summits that do feel they are "reference" level.

How many hours did either of you log on your Summits before they started to sound close to full break in?

Also, if either of you could take a look at the Cardas website, under "insights" there is a link to speaker placement/room setup. Under that link there is a calculator for dipole speakers where you punch in your room dimensions and they give you a general idea of optimal speaker placement with room nodes and such. I am curious as to where your speakers are placed in relation to where they state optimal placement is. Thank you in advance, I am just trying to figure out what will help me tweak placement to help with optimal sonics...

 

[Steve Daigneault]

Steve & Craig,

I totally agree with both of you. It is really an accomplishment to finally get to the point of the entire system sounding great as one unit. In hindsight, I really didn't think of how my amps would do with the Summits. I know my amps did incredible with the Apogee Scintilla's, however all speakers are created different. I am still not holding out hope that more break in will continue to happen. I am also going to experiment with different power cords (as they were already on the way)... then I will work with toe in, rake of the stat panel, and placement after break in. If all of the above don't end up in sonic nirvana... then perhaps a friends Manley Stingray integrated may have to make a visit, with his permission... Just to get an idea, and a baseline between the two.

It is just good to know that there are those out there with the Summits that do feel they are "reference" level.

How many hours did either of you log on your Summits before they started to sound close to full break in?

Also, if either of you could take a look at the Cardas website, under "insights" there is a link to speaker placement/room setup. Under that link there is a calculator for dipole speakers where you punch in your room dimensions and they give you a general idea of optimal speaker placement with room nodes and such. I am curious as to where your speakers are placed in relation to where they state optimal placement is. Thank you in advance, I am just trying to figure out what will help me tweak placement to help with optimal sonics...

my experience is that tweaks make the "right" sound, sound better. it's only after close listening, that i realize things need to be tweaked. but the general overall sound, the general tone, bloom, openness, dynamic qualities, these things are immediately apparent. tweaks won't give you these basic qualities, these things i pretty much hear right away (or don't).

i think it'd be great to hear the stingray w/ the summitts, just as a general idea of how different the amps will sound. i think amps sound very different from each other, and even more so on logans, they are so transparent.

 

[AudioFanKJ]

Hi Steve,

Yeah, I have different tube amps running through my mind right now. Just need to perhaps hear another amp in comparison to see how the speakers react.

I am trying to remember if ML's or stats love a lot of current or a lot of voltage? I think I was told it was one or the other?

Any specific tube amp brands that would be worth looking into as an "over acheiver" for two channel hifi?

I am considering looking into a few that I know I have heard are great performers, such as the Berning ZH270, the Manley gear, as well as others. However, some are output tranformer less, and others are SET, others push/pull, etc. etc. I guess I am going back with as a general rule of thumb as the Summits seem to prefer some tube amps over others... and not necessarily the wattage, what is it?

Thanks to all for any input.

Best regards-

 

[Spike]

I am trying to remember if ML's or stats love a lot of current or a lot of voltage? I think I was told it was one or the other?

According to this article Voltage vs Current by Ralph Karsten of Atma-Sphere, the 'stats panel loves voltage devices to maintain balance throughout the wide frequency range. In this context, the "voltage devices" being tube amplifiers vs current devices being transistor amplifiers. For example, the ML 'stats panels are known to go up to 32 ohms around the 1Khz, tapering down slowly to 1 ohm at 20Khz. This means that the impedance hovers around the 32 ohms to 16 ohms area around the all-important mid-range frequencies. Transistor amps fare less well in this impedance range, pumping out less power and resulting in recessed or lifeless midrange.

Any specific tube amp brands that would be worth looking into as an "over acheiver" for two channel hifi?

Cary V12R or 805C, AES SixPacs, BAT VK55 or VK75, Atma-Sphere M60, TAD-1000, Conrad Johnson, Audio Research, Antique Sound Labs, Joule Electra, etc... to name but a few.

I guess I am going back with as a general rule of thumb as the Summits seem to prefer some tube amps over others... and not necessarily the wattage, what is it?

It's NOT about the wattage, but the detail implementation of the amplifier that will make the Summits sing. In my case, for the 'stats panels, 50 good watts from the SixPacs are much more musical than 100 watts from ARC VT100 or 300 watts from Classe'.

Spike

 

[Steve Daigneault]

I am considering looking into a few that I know I have heard are great performers, such as the Berning ZH270, the Manley gear, as well as others. However, some are output tranformer less, and others are SET, others push/pull, etc. etc. I guess I am going back with as a general rule of thumb as the Summits seem to prefer some tube amps over others... and not necessarily the wattage, what is it?

if you're after a magic midrange, i'd look for amps that use triodes (300b, 845) or an EL34 (which most times you can switch into triode mode), EL84, and octals, like 6SL7, 6SN7. these tubes have big tone. some amps i'd consider warm and a good fit w/ the summitts would be VAC (30/30, 70/70, Phi), VTLs (any of the bigger amps that can be switched into triode mode or, their ST85, 150, 400 amps which use the EL34), Carys (sixpacs, v12r, 805c). from my experience, look for an amp with zero or little feedback. feedback on logans have always suck the life out of the midrange. i've heard this with every amp i've tried on my previous aerius, and now even more with the vantages. the VACs would be my first pick, even tho i love the 805c i have now, the VACs are bullet proof and do it all so well, i think one day i'll be moving up to their Phi amps...

 

[roberto]

if you're after a magic midrange, i'd look for amps that use triodes (300b, 845) or an EL34 (which most times you can switch into triode mode), EL84, and octals, like 6SL7, 6SN7. these tubes have big tone. some amps i'd consider warm and a good fit w/ the summitts would be VAC (30/30, 70/70, Phi), VTLs (any of the bigger amps that can be switched into triode mode or, their ST85, 150, 400 amps which use the EL34), Carys (sixpacs, v12r, 805c). from my experience, look for an amp with zero or little feedback. feedback on logans have always suck the life out of the midrange. i've heard this with every amp i've tried on my previous aerius, and now even more with the vantages. the VACs would be my first pick, even tho i love the 805c i have now, the VACs are bullet proof and do it all so well, i think one day i'll be moving up to their Phi amps...

Hola Steve...you should give it a try with the Margules U 280 SC(www.margulesaudio.com).

Pure Class A, tube audio amplifier, with Active bias o Servo-controled output stage, does not require at any time bias adjustments. High precision regulated voltage in the input and inverter tubes, active damping control, bias meter, 60W/channel, can work triode or ultralinear, among other things can work either as a mono or stereo .

The main design attribute is its great versatility, variable output impedance, independent gain control for each channel, precision metal film resistors, polypropylene capacitors, etc. 4 output tubes, can use 6550, KT99, KT88, KT100.

Yes, I do know that you are looking for a EL34/6CA7...but this is also a superb amplifier. It is designed and built in Mexico, but the components are not made there. Mr. Julian Margules uses the best electronic components that are made in the wold, regarless of price or where they are made...to my ears, it is one of those who carries the "magic"...you find components made in France, Candada U.S.A., Germany, etc...

I have a friend who is using one U-280 with his Summits with an outstanding breath taking sound...one of the best that I had ever heard...I did like it very much...great midrange and easy to understand any musician at the stage. Hope this can help...happy listening,
Pura vida,
Roberto.

 

[aliveatfive]

According to this article Voltage vs Current by Ralph Karsten of Atma-Sphere, the 'stats panel loves voltage devices to maintain balance throughout the wide frequency range. In this context, the "voltage devices" being tube amplifiers vs current devices being transistor amplifiers. For example, the ML 'stats panels are known to go up to 32 ohms around the 1Khz, tapering down slowly to 1 ohm at 20Khz. This means that the impedance hovers around the 32 ohms to 16 ohms area around the all-important mid-range frequencies. Transistor amps fare less well in this impedance range, pumping out less power and resulting in recessed or lifeless midrange.


Cary V12R or 805C, AES SixPacs, BAT VK55 or VK75, Atma-Sphere M60, TAD-1000, Conrad Johnson, Audio Research, Antique Sound Labs, Joule Electra, etc... to name but a few.


It's NOT about the wattage, but the detail implementation of the amplifier that will make the Summits sing. In my case, for the 'stats panels, 50 good watts from the SixPacs are much more musical than 100 watts from ARC VT100 or 300 watts from Classe'.

Spike

I disagree. Please read my review of the ARC VT 100.

 

[Spike]

I disagree. Please read my review of the ARC VT 100.

The beauty of this site is that you get various different (and opposing) viewpoints as a starting point and you'll have to make up your own mind as to which ones are more aligned with your preferences. Here's my post on SixPacs & ARC VT100

Spike