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rowuk wrote:

Amir, In live music, we have intermodulation. Two trumpets or a trumpet and oboe playing together create sum and difference tones that change depending on pitch interval for instance. For music in major keys, this intermodulation is additive - for music in minor keys, it is destructive. Bruckner used this to great advantage for instance. This effect is never as present in playback as in live music. This is because the intermodulation requires LF response to 1 Hz as well as integration of the highest frequencies. Low frequency response is hugely different between audio events in a „smaller“ fixed space and „larger“ spaces. In a typical living room with the doors or inside an automobile, we have a pressure chamber. Our bodies react differently to this LF - a pressure chamber is impossible to musically integrate!

rowuk wrote:

Yes, knowledge and experience with live music is a powerful tool when thinking about musical goals for playback - even when considering that they are very much different events.

rowuk wrote:

Musicality has NOTHING to do with hardware and everything to do with the performance. A musical message can be adequately conveyed with a Bose wave radio or cheap car system. Musicality is not a feature of a sound system in my world. It is the soul of the performer. If we are talking about proper playback, I think we need terms that more closely describe what is happening. The audiophool speak is useless when defining goals. Distortion of geometry (placement of acoustic events), distortion of space (the physical size of the instruments and the distance between them), distortion of articulation (the characteristics that make instruments speak - related to transient behaviour and color). Distortion of pitch (when notes are in tune but sound like they are not) is a very big issue for me. Many audiophile systems have a sense of being high on the pitch. Strings need air, trumpets „brassiness“. Voices need „substance“. Proper playback can be soft and aggressive at the same time. An orchestra can create a billowy cloud and have sparks fly from the wind section. All of the factors mentioned are needed to avoid these unmusical distortions. I do not think that feedback is a problem or that eliminating feedback is a general solution. I use single ended pentodes (connected as pentodes) with Schade type feedback for my amplifiers (RH 307A Super and multiple RH 84). The issue is how the amplifier and speaker work together.  My experiments with pure feedbackless SET amplifiers was not as gratifying (in respect to the distortions mentioned above). Robin

rowuk wrote:

I ran across this site quite a while ago http://rh-amps.blogspot.de and decided to have a go at building one of Alexs amps. The idea of using a real pentode the way it was originally designed for appealed to me.  I had a chance to get some 307A tubes at a decent price and built the 307A Super. http://rh-amps.blogspot.de/2013_09_01_archive.html It is safe to say that I am VERY happy. I am listening to more complete works and almost never zap anymore. The amp has plenty of power and that something special that makes you sit down and listen. The sense of "melody" is very good even at the lower range of the contrabass. Since the amplifiers are done, I have identified some other areas in my playback that need attention. More on the process that brought me to this decision and what it now "after the fact" has fulfilled in upcoming posts.

rowuk wrote:

I have tried the 307A in triode connection in the "standard" no feedback moron 12Axx (in my case 12 AT7) easy configuration with a coupling capacitor and it was "nice". Critical listening was almost impossible, I kept zapping around to find more "impressive" cuts. With Alex Kitics RH concept I have more than enough power (+7Watts?), and very interesting "Sound". Good recordings have a certain "explosiveness" without the etched imaging or mush of the "easy triode". There seems to be some "intelligence" depending on how "thick" the instrumentalist plays. The most important aspect is that I am motivated to keep listening and discovering things not through more "detail", rather by being able to follow the musicians line. The zeners seem to be one of the key factors to the Sound. I tried a resistor, but the entire presentation changed in the direction of "soft". I can compare this to different trumpets that I own. The RH amp has more core and meat, the triode was big and fluffy but was more like a 3d animation than the space that I have when I am on stage. I just turn on the amp. wait about 5 minutes and listen. In the past years I have had EL34 and 84s in various configs, a PP config the longest with relatively inefficient speakers. I changed to a 4 way system with horns a couple of years ago and there was a fairly long list of things that I thought could be better that I thought were related to the amplifier - This is the first major step. Alex Kitic is a very vociferous designer, very convinced about what he is doing - He is very responsive to questions by mail and this venture to get a reference "melody range" for myself has been very good in terms of the sonic results and in getting some independent background behind what I am doing. It is worth looking through his website. I find plenty of inspiration and because he sells nothing and "gives away" his ideas, there is a credibility that is hard to find anywhere else - except here.......

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