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Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum |
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#1 |
diyAudio Member
Join Date: Aug 2004
Location: Indiana
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I am doing this for a class project. My professors laugh at me when I say that I like using vacuum tubes!!
BTW, I'm sure that I left a few things out of the schematic. Questions? Criticism? Comments? |
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#2 |
diyAudio Member
Join Date: Aug 2004
Location: Indiana
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Sorry for the crappy file format.............................
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#3 | |||
diyAudio Member
Join Date: Jan 2005
Location: Hartford
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#4 |
diyAudio Member
Join Date: Aug 2004
Location: Indiana
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I had to do a class presentation, so I showed the design as having fixed bias (when in reality, I'm probably going to cathode bias.) I didn't want to explain cathode biasing.
As far as the operating points go, I was using a simulation- and this was the combo that seemed to yield the least distortion. Right now, I am looking for suggestions to add a volume control in order to make an integrated amp. The input stage (according to the sim) has a gain of roughly 15. I could use higher gain tubes, but then I couldn't make use of my stock of some 200+ 6sn7's!! While I'm on the input stage, do you think it would be wise to add chokes to the preamp power supply (one for each channel?) |
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#5 | |
diyAudio Member
Join Date: Mar 2007
Location: Newark, DE
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You've got a resistor on the cathode. There is a current flowing though the tube that must flow through the cathode resistor. V equals I times R, and consequently there must be a voltage drop across the cathode resistor. Ergo, one end of the cathode resistor is at ground (0 volt potential) and the other end, i.e. the cathode itself, is some volts above ground. Since the cathode is some volts above ground, and the grid is at ground (while quiescent), the whole thing is rather conveniently biased, isn't it? Sorry, I don't mean to sound argumentive. It just caught me off guard and surprised me when you implied there was some difficultly in explaining cathode bias. |
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#6 |
diyAudio Member
Join Date: Aug 2004
Location: Indiana
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I am an engineering student who's stuck in a general project-management class that's full of people who could care less about what I have to say.
Yes, this is a real project- and one I have to see through to completion, but it's also one I care to discuss only with people who are truly "in the know"; that's why I posted it here. |
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#7 |
diyAudio Member
Join Date: Jul 2005
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Cadaverdog, I am right there with you.
There are people in my course who will be engineers. Then there are people who will have an engineering degree. Enough said L |
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#8 | |
diyAudio Member
Join Date: Apr 2002
Location: Belleville, IL.
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__________________
Gavin |
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#9 |
diyAudio Member
Join Date: Aug 2004
Location: Indiana
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Coupling cap:
The reason I didn't use a larger coupling cap was because I thought I could trade a little bass for a bit less muddiness in the midrange. I have since then changed my mind and will probably go with a 1uF. Chokes: I was hoping to get away with not using chokes being that the preamp is ccs loaded (thus hopefully eliminating the crosstalk.) I'll listen to the prototype before I make a decision to add some more weight to this beast! ![]() Input stage current: Upping the current is a good idea; I could easily manipulate the resistors in the input stage to get 10mA I am hoping for approximately 5 Watts. |
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#10 | |
diyAudio Member
Join Date: Mar 2008
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![]() Kind regards, Darius |
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