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In the Forum: Audio Discussions
In the Thread: SET amplifiers

Post Subject: A good question.Posted by Romy the Cat on: 12/7/2014

Well, Gera, a good question in context of your playback. How a person who has multichannel 106db playback with SS amplification and active crossover to explore SET domain? It is not so simple and if you do then probably it would require bringing a single set and speaker level crossover to try. It is possible to have more or less objective subjective judgment of the result but it requires a hell of experience to equate and factor in all changes in the system and to know what exactly to listen for. To have those proper evolution doe it would take time, money and committing many mistakes and taking many wrong routes in the way. If you content with the result you have then stay what you are with exception that If I were you I would get run of active crossover and go line-level with your SS amps.

Now regarding the SETs. Generally what people said above is somehow correct but mostly not. Many things I can’t explain to you as you did not deal with SET. Let me give you just very brief and very shallow idea. You have 106db playback, it means that your system works with very limited currents. The SS amps generally and at minimum currents in particularly have high order harmonics slightly higher then SET would do. SET in class A push VERY dominant second order harmonics that makes sound “pleasurable”, kind, soft, musical and so on. With playback of limiting currents you for sure would like to have no feedback amps but it means high output impedance. With SS you do not care about output impedance and it always very low and the amp in a way do not even “see” the MF drivers. SET however has one extra tool – you can mitigate the loading of the tube (how much impedance the tube see) and by doing it you can write your own harmonic balance of your playback.

Let say you have a bass driver , MF and HF drivers and you drive it from one of three SS amps. The amps for most of the part do not care about drivers are as they push enough current. If you happened to have driver that in context of your amps and your enclosure produces a fine harmonic result (perfectly possible but rare) then you are fine. However what option you have if the harmonic, dynamic, or transient result on one of the driver for instance not good? Change the driver? For you can but we do not build our own drivers, we get what we get… So, here is where SET comes to help.

SET is not only has much lower amount of odd and higher harmonics but SET also you to surgically tune your harmonic, dynamic, or transient to what you need and in case of DCET you can do it for each channel (which is the greatest DSET advantage). You load SET’s output a bit more and you have “richer” and “slower” sound and if you idle it more then you have “faster” and “punchier” sound. In most instanced SS amps to my ears sound like over idled SET…

There are many other interesting things in SETs. Like there are great varieties of tubes with own slightly idiosyncratic sound and those tubes change sound type in response to how they used or driven. SETs are kind of tweaky and they can do anything you want practically with limits. It does not mean that you can’t not accomplish the same with SS amps but I do not have myself and I do not have among my advisers anybody who would have the command of SS design as the level I am interested. It is not to mention that even with SS you can mitigate output impedance and change the interface how the amp “see” the driver.

His is a bit topic and I might go about it for hours but I think you got the initial taste. The biggest question to you is how much itch you have in your ass to try something different. I always advise to use the following as a rule:

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PostID=432

So, do not touch anything in your playback. Listen your playback and try to formulate what you do not like. Name it. Write it down. Then listen inhalations with SET amplification. Name what you like, write it down and listen many more times. Correlate your first and second lists and run it with many different people who have more exposure and more listening experience then you do. Update your first list as your listening objective might change then. Based upon your own guts and the advice of others create an imaginary solution how your new amplification would address the frustration and objectives you have. Now is important part: test the solution. Laterally, crate a test plan with well define definitions and metrics of success. Then bring home a SET of your choose and do not listed the overall sound but rather during your listening execute your test plan trying the targeted listening techniques I’ve described somewhere at my site. If you do hit the definitions and metrics of success during your targeted listening then it is most likely that after investing into upgrade you will not be disappointed. However, you might have many wrong or superficial conclusions during your experiments, no one preserved from that. What you however will have and will develop is the sense of actions and I think it is more important then the result itself, at least to me.

Rgs, Romy the Cat

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