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5th Dec 2020, 1:44 pm | #1 |
Pentode
Join Date: Feb 2020
Location: Waterlooville, Hampshire, UK.
Posts: 201
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Effect of output bias on tone, gain and headroom
I guess many of us here are devotees of Uncle Doug's Youtube channel. I found this recent one to be an excellent examination of the above, conveyed in his usual articulate style:
https://www.youtube.com/watch?v=hgyQ2scnLJY
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Pete BVWS Member |
6th Dec 2020, 3:10 am | #2 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,536
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Re: Effect of output bias on tone, gain and headroom
Pity he doesn't seem to understand the distinctions between voltage gain (as a ratio) and power gain in dB. Why he had to bring dB into it at all made no sense, he could have simply quoted (voltage out)/(voltage in) figures for the hypothetical amplifiers without confusing anything or anybody.
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6th Dec 2020, 5:13 pm | #3 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Effect of output bias on tone, gain and headroom
I managed to hold it together for the first 15 minutes then....zzzzzz.....started to set in, at that point I noticed that it was himself again in the next up in the play list describing how an amplifier works, I got so far as the point where he was explaining how an untapped primary of a single ended output transformer magically removes the ripple voltage, at that point I decided to go and do something more useful instead.
Lawrence. |
10th Dec 2020, 7:37 am | #4 | |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
Posts: 7,667
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Re: Effect of output bias on tone, gain and headroom
Quote:
I found the video in question a bit subjective as the examples were audio, I suggested using FFT and a scope, easier to "see" the difference. Still, that said he puts effort into his video's, isn't on the cadge every five minutes and doesn't have ads turned on, kudos. Andy.
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Curiosity hasn't killed this cat...so far. |
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30th Dec 2020, 3:28 pm | #5 |
Hexode
Join Date: May 2005
Location: London 90% , Northwest England 10%
Posts: 386
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Re: Effect of output bias on tone, gain and headroom
I re-did a YT Playlist for my Google related account , mostly of the Uncle Doug videos, yes they are interesting, particularly if you are going to make (guitar) tube amps, or a comparing old (or new/reissues) amps etc. The vids can be watched speeded up which might help . and their claims as to output etc. He appears self-taught, but looks to have worked in the juke-box repair industry in the past. If you read any of the text books they wander between understandable and confusing too , so while it should not be the main source of understanding is certainly useful for refreshing knowledge, or a starting place. My actual playlist I have attempted to put into some kind of order following the analysis videos and the principles videos , something which maybe that, and other channels, should attempt to do themselves , if anyone wants to see the ordering I have done PM me and I can email a link.
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30th Dec 2020, 10:48 pm | #6 | |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,901
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Re: Effect of output bias on tone, gain and headroom
Quote:
That's a very nice website. He's into interesting things and has good understanding. Well presented and intelligent. The URL went straight into my favourites David
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1st Jan 2021, 3:35 pm | #7 |
Nonode
Join Date: Jan 2009
Location: Bristol, UK.
Posts: 2,062
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Re: Effect of output bias on tone, gain and headroom
The 'signalpath' is 1st rate, it must be the best on youtube for test equipment. Personally, I kinda prefer the range of equipment on 'mikeselectricstuff' eg luggage x-ray machine, quadrupole mass-spectrometer ...
dc |