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Old 22nd February 2002, 10:52 PM   #1
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Default 300B power output vs P-P

OK folks, here's the thing. I know many of you have experienced this, and I have read most of the arguments regarding even order harmonic distortion versus SET dynamics etc etc etc. But...

Why the heck is this paltry 4.5 watt 300B delivering as much bang as my 15 watt p-p??????????????? On the bench there is the even harmonics, but at and beyond full power. At moderate levels the distortion is minimal and comparable to the P-P amp. I know I am not driving this beast that hard yet, and I get more rumbles (house shaking! I even heard it from my lab within the house, before bringing it into my home system) from my DVD's than I recall my p-p amp doing. And they both go down to 10 Hz. What gives!!! This is truly astonishing.

Later!
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Old 22nd February 2002, 11:23 PM   #2
PassFan is offline PassFan  United States
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I don't know Gabe but It makes me glad I bought a SE amp instead of the p-p.
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Old 23rd February 2002, 12:15 AM   #3
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Gabe,

I love Single Ended Amps. Perhaps they are more faithful in their reproduction characteristics than PP amps. However please check that you are not hearing a lack of damping..... which usually gives a bloated and not well defined base. What is the primary impedance of your output tranny and how many stages do you have in your amp?

I am not trying to be negative here. I am simply curious.... to understand what is happening at your place.

Mohan
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Old 23rd February 2002, 12:28 AM   #4
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Gabe,

On second thoughts....we should be looking at the primary inductance of your output transformer at say 50Hz or 120Hz.

Mohan
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Old 23rd February 2002, 01:02 AM   #5
PassFan is offline PassFan  United States
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Mohan:
Gabes amp designs can be seen at his web site http://gabevee.tripod.com . He has a SE 300B, a SE 6L6, and a 15 watt p-p.http://gabevee.tripod.com
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Old 23rd February 2002, 04:04 AM   #6
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Hey Mohan,

From what I understand, triodes generally have a very good damping factor due to their already low internal impedance. Reflected out to the speakers it would be, if it is 600 ohms, then it looks like 1 ohm to the speaker. If I read all those posts and theories correctly. While it isn't like the damping factor of a gazillion of 200 parallel output transistors with 200 dB of NFB (of course, I exaggerate), it is decent enough. No, the bass sounds very tight and controlled.

I have a pet theory. I believe that the output of the transformer closely matches the speaker. That is, while the voltage wave is a sine, the current wave is like spikes, where the current is high during the zero crossing, when the speakers movement is the highest velocity. So there is more of the actual power of the amp going to the speaker. Like a generator or... motor. I have heard newer engineers call speakers... motors.

The other thing is that the tube and transformer act as do any two inductors. The parts are greater than the sum. That is, with AC, each inductor has much more voltage across them than what is put in.

Just my opinion.

Don't get me wrong, my p-p amp sounds like real life. Very true to the source, as others who have that particular amp kit claim. If the source is bad, it is bad. That is what I like.

But I am astonished by the performance of this little amp with that tube. I may be thinking to myself "what can 4.5 watts do that 15 can't" and expecting less while hearing more.

Just thinking.

Thanks Passfan!

Gabe
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Old 23rd February 2002, 10:49 PM   #7
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Gabe & Skippy,

Thank you for sharing your pet theory with all of us. I was simply curious and so I just wanted to understand a bit more about the extraordinary low frequency reproduction that was achieved in your amp. That was all.

Mohan
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