Primaluna & Klipsch Cornwall frustration HELP


Well this is a little frustrating. I have a Primaluna preamp and Primaluna Dialogue 5 power amp. Found a great deal on some Klipsch Cornwalls. Heard Klipsch and tubes were made for each other. Hooked them up and it had very little bass. I was expecting a BIG sound. Sounded almost anemic. Hooked them up to a class D audio amp through the Primaluna preamp and it was fantastic. Lots of slam. A great rock and roll sound. These are very efficient speakers so I don't get why they don't sound good through the tubes. 42 watts per channel at 8 ohms. Happened to talk to a Primaluna guy and he told me I needed a more powerful Primaluna amp. That has got to be BS. Do I have bad or weak tubes?? These are KT88's! Maybe they are going out. Who knows. Tried to call Kevin Deal at Upscale but he is out of town. I am not buying a bigger Primaluna amp. Kind of offended that I was even told that. Would the KT120's make a difference? Could it be something else wrong with the amp. Thanks for any help. By the way the amp sounds sweet with small monitors where I don't expect much bass. Thanks for any direction.
128x128dylanfan
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 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.

Did you accidentally connect a speaker out of phase?

Also, hard for me to think you need more power. I have heard Klipsch Chorus that have 15" woofers powered by a 3.5w/ch tube amp, and there was no problem with bass. And the speakers were not in corners or up against the back wall.
I agree. This should be a great combo. Has me racking my brain. No tube people in my area. I will have to order other tubes if I want to switch.
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,
-- Al