Klipsch Cornwalls and Amps I've Tried

[Colin131]

Yes, many times, as you probably know I design and build them and have done so for over 30 years and 25 years commercially. It all comes down to a few things: How loud do you listen in your room, How big your room is and what type of music do you play. I quote the last point because if you have a large room and play your music loud, don't expect a 2A3, or even a 300B amplifier to provide undistorted sound. Check out my article in Sound Practices Magazine "Speaking out", issue 9, pages 20 & 21 from 1995. Although this was written nearly 30 years ago it is still relevant today.



Correct. However, the power often quoted by most manufacturers is widely inaccurate.



Correct. One thing to note is that the power figures quoted by most SET amplifier manufacturers are vastly out. When they quote 8 watts for a 300B amplifier, on the bench into an 8ohm or 16 ohm load they barely measure 4 watts. That is at about 1% distortion. At 8 watts the distortion figure will be 10% to 20%. The Tron Atlantic 300B amplifier I make measures a true 8 to 9 watts at less than 1% distortion. Low distortion and good power can be achieved with good design and excellent output transformers. The latter is super critical for good performance and the transformers need to be large. The transformers I use on the Tron Atlantic are huge and are designed for 2 x 300Bs. I use them for just one 300B, so the bass performance is very good.



As soon as you move away from a Single-ended Triode design, as in one triode driving the loudspeaker, the purity of sound you mention above will rapidly start to degradate. If you need more power it is better to use a single more powerful Triode like a 211, 845 or a GM70. There are other larger triodes but these require very high voltage power supplies which become extremely dangerous for manufacturing, servicing and repair, as well as being in a domestic scenario.



I have been saying this for over 25 years, in that you need to design specifically for high efficiency loudspeakers if you want top performance. The gain needs to be correct, so you have good control of the volume range, as well as extremely low noise circuits. Any noise will modulate with the audio frequencies being amplified through the amplifier and huge degradation will be heard, especially if you have very high resolution loudspeakers.



Correct. You can use a push pull valve amplifier 20-25watts, but once you move away from a SET you will start to lose the purity and linearity of the Triode design. For a start, a push pull amp will require more gain stages and the use of feedback to keep everything in check. The feedback will reduce the gain but in practice the gain is still usually high at 500mV to 750mV for full output. Not forgetting the source Analogue or Digital will be outputting 2 volts, plus there will normally be a preamplifier in-between as well.



Anything more than about 12watts in a normal sized domestic living space will be wasted, unless of course you are using your Cornwalls for parties, or playing disco or heavy rock music at very loud levels.



You can get very good bass from a SET amplifier providing it has been designed correctly and it uses large good quality output transformers, good circuit design and good power supplies. As a guide the output transformers need to be about the size of the valve they are connected too. This is why good SET amplifiers cost money. It's like trying to design a supercar for the cost of a family saloon. The compromises are just too much to expect the proper supercar performance and experience. You cannot make a cheap SET amplifier because the parts required are expensive. That is to do the job properly.

Thanks a lot for the detailed replies. V interesting/informative stuff. Will reply soon when I get some time.

 

[Nagraboy]

Interesting stuff here. I’ve got Cornwall III speakers and I’ve used a Leak 20 and currently an Audion 300B SET amp with them. The Audion has a volume pot so I just use my Icon Audio PS2 MkII valve phono stage straight in, as I certainly don’t need the added gain of an active preamplifier. 9 o’clock on the Audion’s volume control is a comfortable level without adding any extra hum. The background hum level from the Audion is acceptably low but I do wonder what one of the @G T Audio Atlantic 300B stereo amps would be like. Maybe one day!

 

[GT]

Interesting stuff here. I’ve got Cornwall III speakers and I’ve used a Leak 20 and currently an Audion 300B SET amp with them. The Audion has a volume pot so I just use my Icon Audio PS2 MkII valve phono stage straight in, as I certainly don’t need the added gain of an active preamplifier. 9 o’clock on the Audion’s volume control is a comfortable level without adding any extra hum. The background hum level from the Audion is acceptably low but I do wonder what one of the @G T Audio Atlantic 300B stereo amps would be like. Maybe one day!

Just for reference: It's not about the added gain of the preamplifier that is the problem. It's about apportioning the gain in the correct parts of the system. Trouble is that most of the current valve designs are based on old designs (1950s/60s) where power amp input sensitivity is anywhere between 150mV and 750mV. This is far too much gain for todays sources that output 2 volts. The preamplifier is an extremely important part of the system. It's only got a bad name because they are often incorporated into a system where there is far too much gain in the power amplifier and when used into a pair of high efficiency speakers this just multiplies the gain issue. I don't design for other manufacturers equipment. I design a complete system from the source to the loudspeaker. That way it works how it is supposed to work with todays modern sources, with all the amplifier sections working optimally using the minimum number of stages and no feedback for the best purity of sound. That is why a Tron system is so quiet and performs so well with high efficiency speakers.

 

[Nagraboy]

Thanks for that Graham, interesting. Seeing as speakers used to be higher sensitivity than most models today, why are old valve amps so high-sensitivity too? I guess because the older sources were much lower output than CD/DACs. I’ve had Leak, Quad and Radford and they all seemed to go loud quickly.

My system is vinyl-only now, so I’m hopefully avoiding the problems of modern 2V sources. I just use a phono stage into the Audion - but the Audion is quite high gain, so I’m told by Deco Audio. They said they sometimes reduce the gain for customers using very high sensitivity speakers.

I think if I ever had the budget, I’d ask you to build me a phono stage and Atlantic amp to go between my SPU Wood A and Klipsch Cornwalls.

 

[GT]

Thanks for that Graham, interesting. Seeing as speakers used to be higher sensitivity than most models today, why are old valve amps so high-sensitivity too? I’ve had Leak, Quad and Radford and they all seemed to go loud quickly.

My system is vinyl-only now, so I’m hopefully avoiding the problems of modern 2V sources. I just use a phono stage into the Audion - but the Audion is quite high gain, so I’m told by Deco Audio. They said they sometimes reduce the gain for customers using very high sensitivity speakers.

I think if I ever had the budget, I’d ask you to build me a phono stage and Atlantic amp to go between my SPU Wood A and Klipsch Cornwalls.

In the 1950s and 60s valve amp manufacturers used to put most the gain in the power amp section with the possible exception of the original QUAD II system. This was typically because the source components (Tuner, Tape etc) had much lower gain, and the "traditional" preamp back then was more of a control unit with filtering and didn't provide much gain. The upshot is the overall gain of the system was about the same as it is now. Enter the 2 volt line source components era (CD players, DACs, Streamers and Phono stages etc) and using a modern preamp with 15dB to 26dB of gain and you have a real problem using old traditionally designed power amps. The reality is that most modern SET amps were never designed to drive high efficiency speakers. Manufacturers knew they would be used with conventional loudspeakers of 86dB to about 90dB.

Don't forget I make the Convergence phono stage which starts at £1000. Although there is a matching Convergence preamp which is currently solid state, next year there will be a valve version and this will complete the Convergence line up.

 

[Nagraboy]

@G T Audio

Makes sense Graham.

Re: your Tron Convergence phono stage, I did consider it but I have a bit of a fixation with mono vinyl and I really wanted to have a mono switch in the system. I was looking for a phono stage with one, and the Icon Audio seemed a good option to try and has been very nice. It’s frustrating that so few phono stages and preamps have this facility. My mate Ian has ordered a Convergence phono so I might be able to try it out at some point.

 

[Ianp]

@G T Audio
My mate Ian has ordered a Convergence phono so I might be able to try it out at some point.

Rest assured, this will be happening

 

[GT]

@G T Audio

Makes sense Graham.

Re: your Tron Convergence phono stage, I did consider it but I have a bit of a fixation with mono vinyl and I really wanted to have a mono switch in the system. I was looking for a phono stage with one, and the Icon Audio seemed a good option to try and has been very nice. It’s frustrating that so few phono stages and preamps have this facility. My mate Ian has ordered a Convergence phono so I might be able to try it out at some point.

To cater for mono records I also offer a pure mono version of the Convergence Phono Stage, which eliminates any possible earth/ground loops that you get when using mono cartridges into stereo phono stages. This has been very popular in the USA.

 

[Ianp]

To cater for mono records I also offer a pure mono version of the Convergence Phono Stage, which eliminates any possible earth/ground loops that you get when using mono cartridges into stereo phono stages. This has been very popular in the USA.

Nagraboy will end up with a Tron phono at some point, it's inevitable

 

[Nagraboy]

To cater for mono records I also offer a pure mono version of the Convergence Phono Stage, which eliminates any possible earth/ground loops that you get when using mono cartridges into stereo phono stages. This has been very popular in the USA.

That sounds good but then I’d need a 2nd arm and cart…I just use my stereo cart and single arm into a SUT and phono stage, and then use the mono switch. I suppose I could get a true mono pick-up head to switch over when required but then I don’t know if I’d encounter those earthing issues you mention. Integrating both mono and stereo playback does seem complicated. At least a stereo cart played via a mono switch gives an improvement over none at all.