Coincident Dynamo SE-34: SET amp with 300B's - initial impressions

Got mine a couple of weeks ago, but it came with one busted 300B, and it took close to 2 weeks to get a replacement. The tubes are Psvane Black Bottles - I was told they're phenomenal. I have no point of reference regarding that, so will try to take that statement at face value.

Played the amp today for the first time, about 2 hours total. Naturally, both the amp and the Bottles are just starting the long break-in journey, so the initial impressions are rather raw. But here they are.

First, the negatives: as pretty much expected, the combination of low-power SET amp and my Zu Dirty Weekend full range speakers sounds like crap with hi-powered electric music. Thin, bright, and lifeless, as though with a $20 cassette boombox. Electric bass sounds like a dying swan, electric keyboards like they were bought for $9.99 at Toys-R-Us, at the toddlers department. - I'm not even disappointed at that, I had a near-certainty this would be the case with a SET amp, based on a similar, yet much less-pronounced effect achieved with the amp that got replaced in that system with the SET - the PrimaLuna 4 push-pull, with 35 WPC. Electric music was not the forte of the combo, although it did sound half-decent (but half-decent is not what I expect from an over $10k system). The SET amp just made that lack of synergy more pronounced, end of story. So, to anyone into rock, fusion, EDM, and other electric music with strong beats and heavy bass - a combination of low-power SET amp and full-range speakers is not it. I do not blame the amp (or the speakers) for it, the music styles are simply not fitting for that kind of gear.

Now, for the positives. Again, as I pretty much already knew, the combination shines with acoustic Jazz and Classical, and will do justice to pretty much any acoustic music. Everything sounds just like it does in real life. For now, I cannot go into more intricate detail, because I listened in the afternoon, with the A/C blasting in the next room (it's over 90 here today). The background noise, although faint, was enough for me to refrain from using the more delicate professional jargon of audio reviews. Suffice it to say - it sounded good. I hope for the temps to drop in the evening, so I can continue to listen without the added noise, and provide finer details. As I've also noted - nothing is broken in yet, so take all these impressions with a pinch of salt.

The amp is pretty quiet - quieter even than the PrimaLuna 4, but I suspect the stock PL tubes are responsible for that. The PL 4 does have a little hum, if you put your ear close to the speakers, which is otherwise inaudible when playing music. With some judicial tube rolling to replace the stock EL-34's, I think the PL 4 can be made quieter.

The Black Bottle 300B's have only slight hiss, again, only if you put your ear directly against the speaker driver, otherwise the amp is completely quiet, with no hum - a big stone off my chest.

Music used for initial session:

Electric: Kamaal Williams "The Return" CD (highly recommended with SS amp and cone speakers);

Acoustic: Kenny Burell "Lotus Blossom" CD; "Horowitz Plays Chopin" LP (live).

To be continued...

 

Give it time to break-in. I have a 300B SET amp and listen to plenty of rock and roots reggae with no lack of bass.

 

To continue: the amp puts out customary 8 WPC with 300B's. That it's a low power amp is quite apparent from double the lifting job done by my preamp - I have to crank the volume up anywhere from 150% to more than double what I used to do with the PrimaLuna's 35 WPC. But, even with that noted, the sound is not strained at all - the delivery is silky smooth, just needs more push.

Now, for the evening listening session. Another couple of hours, and the music played was Gino Vanelli's "Crazy Life" and "The Gist of the Gemini", both on vinyl, and Chet Baker Plays and Sings - vinyl as well.

Just like with the previous session, electric instruments sound horrible - electric bass sounds like an electric tuba would, if it even existed, drums sound like cardboard (not sure why), keyboards again sound like they're the $9.99 toy type - like mush. However, Gino Vanelli's voice (which should be declared Canada's national treasure, BTW) still comes out great. Zu's marketing text claims their speakers are voiced centered around the human voice - they were not kidding. It's somewhat baffling, sounding like two different recordings played simultaneously, one with a good voice, the other with ****ty instrumentation. The odd part - Vanelli's voice in both recordings sounded a bit horn-y, even though Zu's are not horn loaded, but rather full range single driver. Overall impression is still negative, though. You may say that it may be recording-dependent. Bot no - the same two LP's sound absolutely phenomenal in my living-room system, with the Parasound SS amp and Wharfedale 3-way speakers. And generally, Vanelli's records from the 70's were very well produced and always sound great on the right equipment. So - it was system dependent, no doubt.

But then, then - I put on the Chet Baker "Sings and Plays". And, right after the first song finished, I knew why I bought a 300B amp (and remembered why I haven't sold the Zu speakers). Everything was right where it belonged and sounded they way it needs to. Acoustic bass was well defined, every note was discernible, high-hats sound like high-hats, including with brushes, the upper range of the vibes sounds crisp like angels' bells. Chet Baker's trumpet - that's a whole story onto itself. Generally, the trumpet is a pretty harsh instrument, at least to my ears (especially the right ear). It also happens to be one of my favorite, so I will often brave discomfort and even earache to enjoy my favorite music. Chet Baker happens to be one of my favorite trumpeters, and precisely because his trumpet is simply not harsh. Now, he is no Miles Davis, of course, but - Miles will make me wince, occasionally, but Chet's trumpet never does - it is smooth (if that term can ever be applied to trumpet at all). On some passages, his trumpet sounds almost as velvety as a trombone.

And now for Chet's voice. All the instruments, while sounding phenomenally good, still sounded like a recording, without a doubt. But his voice - his voice was there, in my living room, singing for me, right from the center (great stereo imaging). I cannot tell which part of that magic was attributable to the amp, and which to the Zu speakers - but kudos to both of them. My doubts are gone - this is an amp to keep, and so are the speakers. This is now my officially designate "Jazz system". With the gradual amp and tube break-in, it will only get better, I'm sure.

 

Perhaps "lack of bass" is a wrong term, and I should have said "too bright". With electric instruments, I definitely perceive an over-emphasis of high frequencies, and lack of definition in the low end. But, with acoustic music - the issue is non-existent, see post below.

EDIT: One comment on the "Horowitz plays Chopin" LP: it is a live recording, and I'm never a fan of live recordings. I always prefer a well-mastered studio ones. This one showed too much of the room acoustics, and sounded to me like an aquarium would (not that I've ever heard a live piano played inside an aquarium). I'm also not a fan of hearing peoples' coughing, sneezing, and the like on live recordings.

The piano itself sounded a bit far off - soundstage is not the strong point of this record, and I had to compensate for it by cranking up the volume to more than double of what I would have with the PrimaLuna 4. In the end - I wound up with pain in my right ear. But even still, being acoustic, the LP sounded better and more natural than the original electric music CD I tried playing.

 

I still don’t have any of the issues you’re reporting. Maybe change the driver tube in the amp. It could also just be a mismatch in amp/speakers.

Aren’t Zu speakers sometimes characterized as being a little bright and etchy?

 

Yes. The Zu speakers do have the "love them or hate them" sound profile. But I'm not so much describing the amp alone, as the amp/speakers combo. This amp just makes it more apparent - I hate them with electric music, and love them with acoustic. It was a similar deal with the PrimaLuna, but because it has more than four times the power of the 300B amp, it wasn't as bad. I guess electric music needs lots of power to sound good, and low-power amps just don't have enough juice. I'd be interested to hear this amp with full-range speakers other than Zu, namely, something without super-tweeters in them.

 

How many watts does a very powerful amp put out while driving Zu speakers though? Aren't they very efficient? Even a 200 watt amp will probably only be using a few watts of power, so I'm not sure it's a power issue.

My Sugden drives my PMCs with authority and that's with only 23 watts into 8 ohms. I can get it to play louder than I have gotten other more powerful SS A/B amps to play. It seems that other amps kind of hit a max volume, while the Sugden I can get more volume as I turn the volume knob until it's just too loud and I don't even want to go louder. The bass is a little flabbier than with my Classe CAP-80; for hard rock/metal then, the Classe may be a bit better, but it's not a night and day difference.

With a 300B SET amp though, I can see how this may happen. Haven't heard a 300B tube amp, but I've heard people say they are overly soft. Maybe the EL34 version of that Coincident amp would be the sweet spot.

 

Interesting comments, all of them.

Other than the thoroughly annoying "tweeter" in them, My Zu, Omen definitions sounded a lot like my Altec A7's in the vocals. This was with driving them with a PrimaLuna, Prologue Five power amplifier with KT88 output tubes and 36-Watts of power.

My results with my Zu's and the 36-Watt PrimaLuna power amp are pretty much in parallel with yours.

I think that since the Zu's are highly sensitive speakers, that the extra power perhaps would provide more "oomph" to the lower frequencies and that might help balance out the harshness that seem to be inherent with the high frequencies?

I think that the 8-Watts that the 300B's produce are about as low power as I would use, driving the Zu's.

Even then, as you say, they simply cannot be expected to produce certain types of music that are more dynamic in nature and simply need more power to sound right.

My legacy horn driven A7's are a bit more efficient than the Zu's, so I can drive them to a nice room filling volume with the 3.9-Watt dual mono Decware, Mini Torii, single ended pentode. But that is to a nice room filling volume and not more and even that is with Jazz, Vocals and Acoustic Instruments.

Even then, the A7's only play down to 47-Hz. at their -3 dB. point and a sub is still necessary for Jazz, Vocals and Acoustic Instruments, to provide enough natural bass reinforcement. The Polk DSW PRO 660 works perfectly along with the A7's for this.

I think when you do get to this point with vocals, then you can really appreciate what single ended tube amplification can bring to you Zu's.

I would try to roll some NOS RFT's in your PL Four, as you can do this for about $280, from German sellers on eBay. I have them in a similar powered Audio Note Kit Amp and they really do have that magic EL34 midrange that modern EL34's seem to not quite have. Also, I found that they have a lot of bass, quite like KT88's, which is something that you don't usually see in EL34's.

While your Four is not going to get where your single ended amp is, I think you will be surprised on how close it can come. And that is with all types of music.

I love what a single ended amp can do with a trumpet, which is an instrument that is prone to harshness.

The Altec's being horns, are a natural match for a trumpet, and also because they simply are not harsh, unless presented with a harsh source.

I agree with a couple of the other posts, that the Zu's are still on the bright side, no matter what you do to tame them down.

To get to this level with Zu's, is saying a whole lot!

I do think that as your 300B's and your amp do break-in, that your music will become even more fluid.

When you do get your system to this point, it is amazing how much different changing out to a single ended amp can make with regard to the vocals and the midrange in general.

It is the icing on the cake.

If you wee to power your Zu's with a Line Magnetic 518iA, with the 845 power tubes and 22-Watts, the results would absolutely floor you. It would give you they smoothness of the 4-Watt 300B's and yet possess the raw power dynamics necessary for most genera's of music to be more than room filling loud and perfectly natural.

But living in N.Y.C. in an apartment, I'm not sure that you would be able to take advantage of the benefit that the LM 518iA could provide.

I think that you will get very close to it with your PL Four and NOS tubes.

I think that once your tubes and amp are broken in, then the piano will fall into place and being natural sounding also. Very much so.

Will keep up with your "accurate" reviews...

 

By "power" I do not necessarily just mean raw WPC figure or SPL leves in dB - that it has enough of. Horowitz's LP yesterday played loud enough to give me an earache that required drops. With electric music, I don't even know how to describe it, it lacks the dynamics, the oomph, the feeling that music is powerful and all around you. It's loud but still weak in ways I cannot describe any better. I'm pretty sure it's frequencies.

You know how people say the Magnepans not only need watts, but they also like current, and benefit from high-current amps? For lack of a better vocabulary, it's got the watts, but not the other thing, whatever that thing is.

I'm not making an issue of it - I'm more than happy to play only acoustic music in my bedroom system, and with acoustic music that amp/speaker combo is liquid gold.

 

Did some more listening today: the second LP of Chet Baker Sings and Plays, Sonny Rollins "The Bridge", and Sarah Vaughn with Clifford Brown. All acoustic jazz, and all sound velvety smooth. Voices are simply phenomenal.

 

I think that a lot of this has directly to do with the frequencies.

I can listen to Jazz and certain types of music at an elevated volume level and my ears do not fatigue. The music is fine and I could listen to quality music reproduction like that forever.

Other types of music get really annoying and fatiguing very quickly.

Like the trumpet, the more real is sounds the more pleasant it is to listen to.

That is what I like to achieve in audio.

Big A7's that sound sweet! Not loud!

 

My experience when switching from high-wattage solid state amplification to using a 12 wpc, push/pull, el84 tube amp and then a 300b set amp, 8-10 wpc, are about the same as what @Benzion described. I used multiple appropriate speakers over the years with solid state amps and I have used four different pairs of speakers designed for use with a low wattage tube amp. To my ears, with the gear I used, the downside of the low wattage amps is a lesser amount of bass and dynamics. I believe the bass issue could be overcome with the use of a subwoofer...
However, these days the majority of my listening is focused on vocals, and the 300b excels at that. So much so, that I upgraded from my existing 300b amp and bought one of the Elekit TU-8600R amplifier kits using a 300b tube that are currently popular (I haven't assembled it yet).
I know there are many people who own Audio Note or other highly regarded set amps and speakers who state bass and dynamics is as good as a high quality solid state system, I just personally have not had the opportunity to listen to one of these systems.... That seems like it would be the best of both worlds.

 

That is what I do.

With a "powerful" amp like the LM 518iA, which is a 22-Watt SET powered by 845 tubes, you do get both the benefits of having an SET, plus the power necessary to give you the SPL's any dynamics that you get with more powerful amps than the 300B type.

With a LM 518iA or there new version, simply called the 845iA, you will have more power that you would ever use with your A7-500W's.

Still, they only really play down to about 47-Hz., with their 828 Altec bass cabinets, so a sub helps with regard to both of these issues.

But the realization that I have come to, is that I don't really need the volume, if I do, I still have the Rogue M-150 monoblocks.

I have discovered, with decent tubes, my little Decware 3.9-Watt Mini Torii, it sound so perfectly sweet and room filling for vocals, Jazz and acoustic instruments, driving the A7's, that it is all of the amp that I need, if I use a sub.

So may people will not understand what a SET or in the case of the Mini Torii SEP, can bring to the party, but with only 3.9-Watts, there is no other option that pairing with highly sensitive speakers.

The tubes I have in it now are Tung Sol 6V6GT, modern production and they cost me all of $45/pr.

I look forward to trying the amp with some really old vintage tubes.

Low powered amp, no problem, use a sub!

Benzion, enjoy your new amp! Congratulations!

 

As mentioned before, I have a 300B SET amp along with my Audio Note speakers and there is no way I'd ever need or want a subwoofer. Bass is absolutely not an issue.

The issue Benzion is experiencing is either break-in or a mismatch with the amp and speakers.

 

I have the Elekit TU-8600R with the Lundahl transformers and other upgrades with my home built Audio Note E AlNiCo's and the dynamics and bass are unbelievable on electronica and rock. For otherworldly acoustic bass, have a listen to Django on "Gitane" by Charlie Haden/Christian Escoudé. If your system is up to it, you will have a hard time not just playing the song on repeat as loud as the neighbors will allow.

 

Audio note speakers are designed to run on SETs

 

A 300b set amp is most likely running an output impedance of 4 or 5 ohms. Your speakers may not be a good match even if they are fairly sensitive. If their impedance drops in the lower midrange it would sound exactly as you described.

 

The speakers are 12 Ohm and are connected to the 8 Ohm taps. According to the amp's builder, the speakers and the amp are a match that is "hard to get better", to quote verbatim.

 

You're missing half the point of this whole thread - the acoustic music played through this amp and speakers sounds sublime. It's only the electric music that suffers from lack of dynamics.

 

The Elekit amps do have the reputation of sounding very "modern" and unlike most other 300B amps - and that it precisely the reason I didn't buy it. Why buy a 300B amp that doesn't sound like one? I was intrigued by the old-school SET thing, and got exactly what I was looking for. That it is only good for acoustic music (to my ears) is not much of an impediment to me, as I was ready for it and do have another system great for electric music. But, if I wanted a single amp for all my music - I'd surely be disappointed, so let that serve as a warning to others who consider SET amps and have a lot of electric music in their collections.

 

Glad you’re happy with your new amp!

It’s curious that the dynamics suffer if the music is made with electric instruments. The Zus are known to be incredibly dynamic, fast speakers. Shouldn’t that dynamism come through regardless of whether the music is “plugged in” or “unplugged”?

 

Honestly, I'm not technical enough to know why, I'm only describing what I'm hearing. And it's not the volume that is in question - it gets ear-bleeding loud, but something is missing from the sound when electric music is played.

 

To put my money where my mouth is, anyone within reasonable distance from me can have a listen for themselves - pm me and I will welcome you in my home to a listening session, so you can have an idea of what it sounds like, especially if you're considering a SET amp for yourself.

 

As benzion said, the get loud, but not balanced loud. You just need more than 8-Watts to get some significant bass with balanced dynamic's.

I can get the with the KT88 based PrimaLuna Prologue Five but there is no way you are going to get there with 8-Watts.

You just don't have the same bass demands with vocals.

 

I've got no doubt that what you're hearing is valid. Getting the midrange right is 80% of the battle, and if acoustic music sounds good, the amp/speaker combo must do that well. So I'm guessing it's in the frequency extension top to bottom.

Had you heard other 300B SET amps at shows or dealers in the past, and does the Coincident resemble those? Again--you're happy with your amp, so if it ain't broke... But like you say: why buy a 300B amp that doesn't sound like one?

For my own experience, I once paired a Line Magnetic 508ia amp (SET, 48W) with Zu Soul Supremes. The bass was somewhat lacking for me, and the sound was a bit tubby/ill-defined. There were limitations on where I could suitably experiment with speaker placement, so it's possible that in a different room they would have gotten along better. A push-pull Leben did a better job at a more linear top to bottom presentation (but wasn't as 3D or involving).