Belle Klipsch review

I am pretty sure my PrimaLuna ProLlogue 5 will come with reproduction Genalex KT88s. If not then the EL34s. I have a lot to learn about tubes. I used to swap out tubes in a Fender 57 Twin Tweed RI I had. I loved the LOOK of the Ruby 6L6 (I think) they looked like coke bottles and need a special sling to keep them from vibrating out (as they hang upside down in a guitar amp).

 

[QUOTE="SKATTERBRANE,

The ALK crossovers is purported to flatten the impedance. Plus it has L-pads for the tweeter and has movable connection to adjust the midrange attenuation.[/QUOTE]

This is true and they do but, they also use the cheaper iron core inductors vs larger much better air core inductors and other parts.

 

The Five is comes with KT88 tubes. The Four, which is being closed out for $899, comes with EL34 tubes.

This is true and they do but, they also use the cheaper iron core inductors vs larger much better air core inductors and other parts.[/QUOTE]



ALK offers several different crossovers that have different features and different price points.

Al uses very high quality parts for his crossovers. He uses both air core and iron core inductors, where applicable and also when offering his economy crossovers.

The photo above is of his ES-400's. This is his extreme slope crossover designed for the Klipschorn.

Here is Al's Universal Economy crossover.



Here is my Gentle Slope crossover that crossovers the HF horn at 500-Hz. It is the crossover in the front. It is sitting on top of one of the Altec A7 VOTT's.



The crossover in the rear is not Al's but a custom build. It crossovers at 6-kHz. for the super tweeters.

 

Pretty sure the 5 will take EL34/KT 77 tubes as well.

 

Oh yes. I bought a couple of extra quads of EL34 tubes from one of our members for that very reason.

The Four was designed to use EL34's or tubes like the KT77's.

The Five is a little bit beefier of an amp.

From the Upscale Audio Web Site:

"Want the ultimate? Classic Ultralinear all-tube sound, with all the body and glory that you could ask for. For an additional $250 over the EL-34 equipped Prologue Four, you will get an amplifier that has more power, better bass authority, and a little more air on top, but never edgy.

In addition, the ProLogue Five comes specially equipped with the following upgrades:

• Upgraded Solen capacitors made in France. The result is an even better midband and wonderful clarity.
• Fast Recovery Diodes. Resulting in increased definition and detail, especially when the music becomes complex.
• KT88 Output Tubes. We use the current production copy of the legendary Genalex KT88. The tube sounds wonderful, with tremendous body and punch, while still giving you the warmth and humanity you'd expect from an all-tube amplifier.

The ProLogue Five starts with the same basic topology as the award-winning ProLogue Two integrated amplifier. Further improvements are realized from new driver and phase splitter circuitry. The result is no need for any negative feedback. This means even more natural tonality and better overall musicality."

PrimaLuna ProLogue Five Poweramp Review by Upscale Audio's Kevin Deal

 

And the PrimaLuna will also take 6L6 tubes....these may be just the ticket for the Belles as they are for Klipsch La Scalas....as in McIntosh MC30s (prior experience).

 

Al uses very high quality parts for his crossovers. He uses both air core and iron core inductors, where applicable and also when offering his economy crossovers.



Here is Al's Universal Economy crossover.
Quote: Well I could be mistaken but I don't ever remember seeing any air core inductors offered by Al... To be clear my statement was based upon the original Universal Xovers that Al made, I had a pair and know for a fact what parts were in them.

 

I got the PrimaLuna power amp. It is very good! I took the Xiang Sheng preamp out and put in my Spectral DMC-15. This is the ONE thing that made the most difference in reducing that bothersome resonance so far. All my other preamps, Crown, Theshold and the Xiang Sheng had it to various degrees. The Dynaco amp and the PrimaLuna amp reduced to a little degree, but the Spectral preamp did it the most. Everything matters, that's for sure!

 

There is one common element to Klipsch. It isn't boring either in discussion amongst its users or in the holy grail search for optimal rooms, room placement, amps/preamps and mods.
As for the choice of speakers I have had experience with Heresy Is, Forte IIs with Crites mods, and Jubilee with Fastrac horns and Faital drivers. Besides the obvious priority of room and room placement, the amp is the next most critical thing in my opinion. My favorite thus far has been Justin Webers's Ampsandsound products. I have tried the Little Ben, Stereo 15 (which has been since upgraded to Stereo 15 Special Edition) and the Casablanca mono blocks. These amps are dead quiet which is a requirement for high efficiency speakers and the power is more than adequate for any Klipsch Heritage speaker. Give them a try if can.
Stereo 15 Special Edition - Amps & Sound
Brad

 

The Spectral DMC-15 is phenomenal. The timbre and the soundstage the best I ever heard. There is still that resonance but it is greatly reduced. It may be because of speed, or maybe it is just a matter of perfect impendence matching? Oh, and ANY of my amp combinations have too much gain. What is nice about the Crown power amps I can turn DOWN the gain. What is nice about tube amps I can use different tubes. The primary gain tubes on the Prima Luna are 12AX7s. The secondary, just before the power tubes are 12AU7. I replaced the 12AX7 with 12AT7 and that helped lower the gain a little. Then I tried 12AU7 in the 12AX7 place, so that I had all 4 12AU7. That lowered the gain some more and it improved the sound overall. I did not want to run it with tube types not recommended (they say if you want to lower the gain go 5751 which I do not have). So, is there any long term problem running the sweet sounding 12AU7 in place of the 12AX7? I do not want to lower the gain in a preamp, I want it to happen at the power amp.

 

Running the 5751's is almost the same as running 12at's or 12au's the all have less gain than the 12ax's...

 

The way I understand it is 5751 is 70mu, 12at is 60 mu and 12au is 20 mu. (12ax is 100 mu) Yes, I WANT less gain. I tried both my 12at and my 12au and the 12au has the least gain and sounds the best. I just wanted to know if there is any long term (or short term) damage doing this. I was looking at plate resistance, plate voltage plate dissipation and wondering what ill effects on the amp the differences might have. I do not understand all the specs but maybe something about them could be harmful in the wrong application:



12AT7

DOUBLE TRIODE (separate cathodes)
Heater Voltage 6.3-12 V
Heater Current 300-150 mA
Plate Voltage 250 V
Plate Current 10 mA
Plate Resistance 10,900 Ω
Amplification Factor (μ) 60
Plate Dissipation (max) 2.5 W

B9A base pinout



12AU7

DOUBLE TRIODE (separate cathodes)
Heater Voltage 6.3-12 V
Heater Current 300-150 mA
Plate Voltage 250 V
Plate Current 10.5 mA
Plate Resistance 7700 Ω
Amplification Factor (μ) 20
Plate Dissipation (max) 2.75 W

B9A base pinout

12AX7


DOUBLE TRIODE (separate cathodes)
Heater Voltage 6.3-12 V
Heater Current 300-150 mA
Plate Voltage 250 V
Plate Current 1.2 mA
Plate Resistance 62,500 Ω
Amplification Factor (μ) 100
Plate Dissipation (max) 1.1 W

B9A base pinout

 

I doubt that you would actually cause damage to you power amp by replacing any tube in the family above with one of the others that have less gain.

I would, however, contact Upscale Audio's technical support department and pose this question to them, to be perfectly safe. Since no one on the forum has designed the amp, it is better to pose that question to the factory authorized dealer for PrimaLuna.

Owning the Five and having personal hand's-on experience with it, I'm not sure why you are trying to make these particular changes to the gain stage of this power amp.

Your preamp puts out a line level signal, the PrimaLuna is designed to accept a line level input, so what do you find are the issues here?

I drive the large A7's with the Five and I have not experienced any issues with it being over driven. The A7's are 103-dB efficient, until you attenuate the HF horn down a few dB's to match the lower efficiency of the woofer. The La Scala's are even more efficient than the A7's, but over, -driving them with the power amp was never an issue.

What you are doing is changing the overall design of the Five. Since it is your gear, you are free to do so, but why I am asking? I just don't see the purpose doing for this?

In an preamp / power amp set up, you control the level of the power amp input with the volume control on your preamp. If you are experiencing too much gain at through the inputs of your power amp, you only need to reduce that volume level of your preamp, and reduce the signal level that is driving your power amp.

Here is my 6SN7 powered preamp.



Between the preamp, which sits directly behind me and therefore the volume control is not readily accessible for the analog volume control. I have inserted a remote analog volume control between the preamp and the power amp. It is a now discontinued Emotiva, ControlFreak. It is designed to be inserted between a preamp and a power amp. My model has RCA connectors, but they also made a balanced version available for only $10 more ($60).



The Peachtree iNova is used to as a central point of control, to select the input that will be playing, the ESS Saber DAC and the class-A preamp only. All of the power amplification stages are outboard. The iNova's volume control, controls the front mains, the rear klipsch WF-35 towers (including one La Scala and a Polk Audio rear sub).

The power amps for the A7's are usually located behind the 4k TV screen. Here is the disconnected PrimaLuna, sitting to the left of the Audio Note L4 kit amp, which is currently being used to drive the A7's.



You also mention "resonance", I'm not understanding where the resonance is coming from that you are speaking of. The older vintage production Klipsch speakers were built out of plywood, while some of the vintage reissues ae manufactured out of MDF.

In either case, My brain would implode long before I reached the point of encountering any cabinet resonance issues would ever come into play. I have never had the urge to turn um the La Scala's as far as they can go. It is enough to just listen to them at lower volume levels.

 

If you heard the resonance I am hearing you'd get back in your car and drive into the woods and become a hermit.
Overdriven is not my issue at all, far from it!
The Belles are so efficient that any of the preamps I have (all are at the 7 0'clock position when full off) when turning the volume to 8 is loud enough and 9 is TOO loud. But my ENTEC subwoofer, which was loud enough with any speaker of 99dB sensitivity or less was loud enough to match these other speakers. With the Belles the subwoofer turned up all the way is not loud enough. Reducing the gain of the preamp will not solve this. But reducing the gain of the power amp will. I will read you entire post later today and address whatever else you have brought up.

 

I've read somewhere that Spectral preamps generally only work well with Spectral power amps. This is sort of hard to confirm, being as though there is not much written about them anywhere. But I'm not sure many folks use Spectral gear out side of a Spectral system, that also needs their special cables as well.

 

Yeah I have heard that too. I have had three Spectral preamps, all of them are great. I never had a Spectral power amp, though the ENTEC subwoofer has its built in amp by the same people who make Spectral amps. My Belles sound the BEST with the Spectral preamp regardless of power amp. And the PrimaLuna power amp sounds the best regardless of preamp I have .

 

This is exactly why you need an ajustable xover!!! So you can attenuate the mid driver to match the other two drivers better!!! That way you don't have to worry about the gain on your amp or in your pre amp....

 

Whew! Just read the whole thread. Like an audiophile reality show (that would be cool...to us).
Man! No offense but this seems like a LOT of effort to get a pair of 5k speakers to sound good but I know the predicament. Glad they are getting there.

 

A 100lb speaker with 104db sensitivity requires some effort. The margin for error is pretty thin.

I’d still say a SET amp with 300b Tubes is the ideal power. A mc225 would also be a fun amp to match with them. And I’m sure the primaluna is lovely.

 

The problem I described that you quoted isn't about the 3 drivers in the Belles. It is about the Belles are too loud compared to the subwoofer. The subwoofer can't get any louder in comparison. I would have to attenuate the signal going to the Belles, not just the mid driver. The subwoofer worked fine with Heresy IIIs at 99dB sensitivity with the subwoofers at 95% maximum gain. 100% maximum gain isn't quite getting there with the Belles. Putting 12AU7s in the power amp makes it all work well. (except no matter what I do so far gets 100% rid of that resonance).

 

Oh sorry my mistake I should have read more closely, with that being said you still are gonna need much better xovers at the end of the day...

 

Yes, I agree, ALK Universals on the way. I am not interested in active crossovers however.

 

I didn't mention active xovers just adjustable or custom made ones, is all you will need. The Universals will for sure improve the sound but, all he makes now is a cheaper version than he did years ago. They will need much better parts...

 

Just trying to understand your issues.

I was having a similar problem a few years back, when my front amp was getting too much of a signal, as compared to the rear amp.

I used a Harrison Attenuator



You can get them with 6-dB's of attenuation or 12-dB's of attenuation.

I'm glad that you are liking the PrimaLuna Prologue Five!

Since we both have similar speakers, I'm trying to understand your "resonances" issues. My La Scala's are heavy plywood commercial cabinets, which are covered with Baltic Burch plywood. Do you have an older model that might have been built out of plywood. I wasn't sure if the home belle's were ever made in plywood.

I know that many of their newer speakers are now made with MDF.

I just have never experienced resonance issues with the La Scala's. All of these legacy Klipsch speakers have heavy reinforced cabinets. I could not even imagine how loud I would have to turn up the La Scala's before I might experience cabinet resonance issues?

 

The Belles are plywood too. I am thinking the resonance is a spike in the relationship between the crossover and the drivers, the opposite of a notch filter in effect. What is so interesting to me is different preamps have either a lesser or greater effect on this resonance. But the actual frequency band of the resonance remains the same. I am thinking it is a matter of electronics rather than cabinet. (just a wild-assed guess on my part)

Thanks for the attenuation suggestion. The ALKs will have the attenuation for the mids and tweeters in relation to the woofers in the Belles, but those inline attenuators will address the subwoofer in relationship to the Belles as a whole.