Are your speakers placed in the room's corners or against the wall? If not, try them with there as that is how they are designed to sound their best.
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Cornwall's with no bass slam with a valve amp that is a no no.
In the corner against the wall they must go.
Running KG 4's 94db with a Line Magnetic 211IA in 12w triode in the corners close to the walls and they shake my privates, more slam more dynamics I do not need.
And Cornwall's @98.5db stomp KG 4's in both regards.
Bigger amp no don't think so, play with it.
See the Stereophile review of this power amp some interesting observations. Bias settings etc.
Try the different output taps, play around.
I use the power amp with some KEF ls50's and Dynaudio X12's. They sound great for their size. I picked the Klipsch up so I could have a rock and roll set of speakers when I wanted to play Stones etc. I am used to the monitor sound through the Primakuna but I gotta say all the speakers sound much better through my Luxman 505U or through the Class D Audio power amp playing through the Primaluna preamp. Thinking about trading in or selling the Primaluna power amp and going with a really good solid state amp. Thought I might check the forum for other ideas before I do anything rash. I have 2 good solid state Amps now snd I like the tube sound so wanted to try to figure this thing out.
I use a Primaluna Dialogue 2 with my Cornwalls, and it is a fantastic combo. You definitely do not need more power - I often use the 21watt per channel setting on my amp, and there is absolutely no lack of bass - that amount is more than enough power for those speakers. By the way, the Cornwalls do not have to be against both the wall and the corners, it can be one or the other and sound great. Mine are against the wall, near the corners.
Unless you just got a lemon for the amp, perhaps there is something wrong with the tubes. I use EL-34s in mine, but the KT88s should provide plenty of bass. There are many different tube options that will work with those amps, you should be able to find a combo that works well.
This should be a great combo.Not necessarily, as I see it.
According to the impedance curve shown here for the Cornwall II, its impedance is in the vicinity of 5 ohms at most bass and mid-bass frequencies, while rising to much higher values at most higher frequencies.
Learsfool (whose sonic perceptions are always above reproach IMO) mentioned that he obtains excellent results using a Dialogue Two with Cornwall IIs. However your Five is described as using zero feedback, with its description pretty clearly implying that the Two, from which a lot of its design is derived, used significant amounts of feedback. Which presumably means that the unspecified damping factor of the Five is significantly lower than that of the Two, and its output impedance (which is inversely proportional to damping factor) is therefore significantly higher than that of the Two. Typically a zero feedback tube amp will have an output impedance that is a significant fraction of the five ohm impedance your speakers have at most lower frequencies, which will result in an under-emphasis of those frequencies relative to frequencies at which the speaker impedance is much higher. Which in this case would mean an over-emphasis of most frequencies in the mid-range and lower to mid-treble regions, relative to the bass and mid-bass regions. All of that being in contrast to the frequency response that would result with the near zero output impedance and very high damping factors of nearly all solid state amps.
So while several good points and questions have been made and asked, including those regarding trying the 4 ohm taps, checking speaker phasing, and the possibility of weak tubes, it seems to me that the damping factor and output impedance characteristics of the particular amp may simply not be a good match for how the impedance of the speaker varies as a function of frequency.
Good luck. Regards,
Over my head Al but thanks for the response. So what kind of speaker sounds best with this kind of amplifier?? Or should I ditch the thing. Not enough adequate power for my Dynaudio X12's or my KEF LS50's . That's why I got the Cornwall's. Now this tube amp will not work with Klipsch speakers. What the heck works with the amp?
I have Primaluna mono blocks 70 watts, and 150 watts SS at high volume has better definition and bass; but, and here is a big but, the Primaluna sounds better; however, if you crank up the volume on the Primaluna, it loses some definition.
The solution is to be satisfied with a lower volume, or buy a bigger "tube" amp, I don't think you'll be satisfied with SS; while they sound good short term, over the long haul there seems to be something missing. Good luck.
To give you something to look forward to, with my speakers, the difference between using the 4 ohm and 8 ohm taps is substantial. In 4 ohm the bass is nice and tight - very present. In 8 ohm it is less transparent in the bass - but not necessarily boomy, just makes the sound a bit foggy. My speakers are nominally 8 ohm speakers.
And, in my Dialogue 2, I use Tong-sol 6550's which I find add some tonal richness in the upper bass/lower mid range when compared to other 6550's and KT88 (that I have on hand, anyway).
Out of curiosity are you using a Dialogue 3 pre-amp, or are you using its predecessor, the PL3. I ask because until I matched my old PL5 with the PL3 its bass was weak/thin (when using ARC and a Magus pre-amps.
OK- in review, here are the things you need to try:
1) try a different tap (4 ohm)
Notes: the speaker is nominally 8 ohms and likely has a nice impedance bump in the low end that might help your amp out. Any notion that this amp cannot control the woofer is nonsense- this speaker was designed for amps with high output impedance.
I am thinking that the impedance is not the issue here.
2) try reversing the phase of one speaker *only* (not both!).
Notes: If it appears that you have your speakers wired correctly in phase, it may be that your amp has its output out of phase in one channel. In a zero feedback amp, this could happen due to a wiring error as there is no feedback to cause the amp to oscillate (which it certainly would do if it had feedback).
IOW, I suspect phase is the problem.
FWIW, we have customers using that speaker with our M-60 amplifier, which also has a fairly high output impedance and they report impressive results. So you should be able to make this work unless something is outright wrong with the amp.
I am using it with a Primaluna Premium preamplifier. Thanks for the advice stmadphere. I will reverse the phase of one speaker when I get home over Labor Day. This amp hardly gets played because I travel so much. I would like to just go home, turn it on for the little bit of time me I am home and enjoy it instead of trying to figure out why it doesn't sound right.
08-22-15: DylanfanFYI, in addition to causing a lack of bass a polarity inversion in one speaker (i.e., + and - being interchanged, either due to a connection error or due to a wiring error in the amp), would result in imaging that is vague, diffuse, and hard to localize, and would probably also cause the midrange to sound a bit strange.
I suspect that going to the 4 ohm tap will strengthen the bass at least a little. But to what degree, and with what other effects, are hard to predict. It's definitely worth trying, though, as several of us have suggested.
If the amp has not been played much, it may also need some break-in time. Filter capacitors don't like to sit around discharged; its best for them to be played and as they are played they get more efficient. As this happens, they become more effective at their job (power supply bypass) and one of the results can be better bass.