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In the Forum: Melquiades Amplifier
In the Thread: More 6E5P-6C33C amps.
Post Subject: If not then all bets are offPosted by Romy the Cat on: 10/27/2010
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 Cosmos wrote:
Indeed it took me a very long time to decide upon regulate or not. I ended up with regulation option to save some chassis space and weight, otherwise I would need at least 10 kilos more and 30% bigger space that would make the whole amp impossible to move and redicoulously big for a 15 watter. On the other hand regulation is good for a commercial machine since its easier to live with less adjustments for the final user, moreover the sound of the regulator is very similar with slightly better detail and bass, however chokes provide slightly easier and softer sound to my ears, but there are times you got to make some choices and regulator was mine.

Yes, chokes would make the amp bigger and they toss a lot of shaking inductivity around that stress chassis a lot. The choke regulating is most likely goes with two chassis configuration that automatically trigger much higher price for a commercial product. Still, leaving the economy aspect aside, I heard that the supporters of regulation feel that there is some not economic but sonic advantage to have 6C33C regulated. Well, I guess we can learn the final judgment about it in our next lives…. BTW, if you have a regulation on board then it would be very easy for you to implement a switch for one heater operation for 6C33C…
 Cosmos wrote:
You are absolutely right on frequency response method of testing and I will correct my site asap, however that was not at all intentionally as expalined in my previous post.

Be very careful with that. Since you are a manufacturer then your job is not to demonstrate sanity but to compete with idiots who claim that their 6C33C amp can run a video signal. They just forgot to mention that it will do it at .00000001W…
 Cosmos wrote:

On the other hand my measurements are correct and really do not understand why you do not believe these, just for your information my equipment is recently calibrated and are the following, tektronix SG502 signal generator, HP3478A, Fluke 8840A, Fluke 8060A, HP400H, tektronix D15 and 561A, these are used for measurement of frequency and Vrms and also EMU0202 as spectrum analyzer. Note also that the load used for these measurements is a 50W 8ohm power resistor. If you would like me to measure something else please be my guest. I really do not get why you are saying that the response you are getting is only 20-22KHz, maybe your output transformers are not up to the task? Maybe I can help you on that.  

Might be I do need a help what I witnessed is what I report upon and what I believe to. The 20-22KHz response is incredibly good response at full power for full-range 6C33C SET amp. Most of the SET amps do not go even close to it. This conflict between inductance and capacitance in SET transformer is the bitch for SET design and this is why I went DSET. Frequency response of SET amp I mostly restricted by OPT and the only know to me objective way to measure the frequency response of a transform is a full power. I uselessly set my SET into symmetric clipping at 1000Hz (by current and voltage) and then drive input signal to the level just below the clipping. This I consider a full power and ALL measurements of frequency response I do ONLY at this level. Then I roll the generator down until I get a 0.1-0.2 dB less. This is the beginning of the LF roll off.  Then I roll the generator down more until I hit -3dB. This is the LF cut off frequency. Then I do the very same foe HF and the only things change is the timing in my scope. I have seen very few SET amps that do 20-20K at full power. The 9Hz to 122KHz is absolutely imposable bandwidth in my view. I have in my LF channel run to 7.5Hz but it uses a transformer with very high inductance, mass and size, much- much higher than your 10H. The  transformer is7.5Hz-800Hz and this is DSET transformer, it has no sections on secondary and case less about capacitance as it works only on LF. I did not see any transformer that has all provisions for maintaining HF and minimum HF phase shift and at the same time to be able to get down to 9Hz.   I my only presumption is that you are the amp full power. Again, I do not care how many watts it is – it MUST be juts under the clipping. If not then all bets are off. This is how I see the things.

Rgs, Romy the Cat

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