Well that's a personal choice. People do all sort of things...
I would never waste a 45 tube with those cheap transformers or parafeed or any other compromise like that. A good output transformer for the 45 is not expensive by any means.
Good for you. But please let's not start the usual thing like "this is marvellous just because I have it". You should as least compare it directly to something like the EDCOR XSE15-5K to make conclusion.
That's why I said people do all sorts of things. Now I tell something else. You don't listen to music just by your ears. The human body is full all of sorts of receptors and that's why music really is a therapy not just for babies in the belly.....So to cut it short, at least the frequency range at higher end should be twice wider than the usual 20K for the "full experience"....
Even small fullrange drivers get to 40KHz. If you look at power spectrum by integrating the emission over, say +/-30 deg, the amount of emission at 30KHz is only few dB's lower than audio range and 40KHz are some 10-12 dB down (just an average figure to give an idea). However at an average listening level of 70-75 dB, which is modest really, the amount of ultarsounds is already enough to stimulate other receptors. Even the chair or sofa where you sit make a difference!
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CFB will totally change the sound of those fullrange drivers...more likely for the worse. In particular, off axis response will drop significantly already from 4-5KHz and completely altering the presentation. The "trick" of zero fb triode amp is that its relatively high Zout will cause self-equalization with the coil inductance of the driver giving a more balanced overall high frequency response and no need for a tweeter.
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Pentode/tetrode with moderate CFB surely a better idea as it has no fb triode-like behaviour.
To be precise that's not even tetrode with CFB but rather a variant of the UL. To be true pentode/tetrode it should have the g2 referred to the cathode in AC with a small capacitor between the electrodes.
To be precise that's not even tetrode with CFB but rather a variant of the UL. To be true pentode/tetrode it should have the g2 referred to the cathode in AC with a small capacitor between the electrodes.
McIntosh and early leak used tertiary windings for CFB, as did Tim Paravacini in his SE EL509 triode strapped .
I build a SE EL509 triode strapped with a custom wound Amorphous double C core with a %5 tertiary winding for feedback, it improved the overall performance and to all that listened to it preferred it to the tubby midrange SE300B .
Bass was tight , much tighter than the 300B
I build a SE EL509 triode strapped with a custom wound Amorphous double C core with a %5 tertiary winding for feedback, it improved the overall performance and to all that listened to it preferred it to the tubby midrange SE300B .
Bass was tight , much tighter than the 300B
I already have more OPTs than I'll be able to use in my lifetime, and now I somehow want a pair of these Sonys too
Looks like the frequency response is much better at 600 Ohm taps - might make for a decent preamp (which I also don't need) OPTs or something...
Well that is a better idea, IMHO. The poor high frequency response of those transformers into the low impedance tap is very likely due to the unused part of the secondary.
There is too much difference between the tap and full secondary (in terms of turns). When you only take the output from the low impedance tap and do not use the rest of the secondary the FR gets poor. I would not be surprised if the FR (-1 dB) goes from 12KHZ to 20-25KHz when switch from low impedance tap to full secondary.
For the same reason it is a good idea to use the cathode feedback rather than leaving most of the secondary unused. But low mu triodes are not the best candidates for this, IMHO.
A tubby SE300B is a bad amplifier. A proper 300B amp doesn't sound tubby at all. The tube alone doesn't make the sound.
There is no tapped secondary... the 8 ohm and 600 ohm secondaries are separate. I havw had 10 or so pairs of these go through my hands over the years and I can say that they sound great within their limitations. Of course a modern trafo with modern materiels will walk all over them....
If you dont expect much bass they do well with a trioded 6V6 or EL84. I have a headphone amp with them and it is quite good.
If you dont expect much bass they do well with a trioded 6V6 or EL84. I have a headphone amp with them and it is quite good.
What tube(s) do you use in that headphone amp and which headphones do you use?