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Old 5th January 2010, 07:56 AM   #181
CLS is online now CLS  Taiwan
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I've been thinking, what's the difference between a differential pair and common cathode sigle ended circuit + shunt regulator?

Ultimately, the current flows in them form a seesaw - one high/the other low, don't they?

I only followed this thread loosely. Sorry if that would've been brought up.
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Old 5th January 2010, 04:05 PM   #182
Salas is offline Salas  Greece
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Quote:
Originally Posted by Joshua_G View Post
Salas, you feed your 6V6 line stage from Maida-like series regulator. Yet, in your "Simplistic Mosfet HV Shunt Regs" thread you say that the Shunt regulator sounds much better than the Maida one, which makes a lot of sense. Usually, when all else is equal, shunt regulators are much better and quieter than series ones. So, wouldn't this 6V6 line stage benefit from Shunt regulator?

I'd rather start the project with one type of regulator and I trust your experience.
When I had made that build I had not developed the HVSS yet. It will normally be recommended over the Maida. It takes a 400V driver PNP for over 300V that we need here.
Simplistic Mosfet HV Shunt Regs
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Old 5th January 2010, 04:08 PM   #183
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Quote:
Originally Posted by CLS View Post
I've been thinking, what's the difference between a differential pair and common cathode sigle ended circuit + shunt regulator?

Ultimately, the current flows in them form a seesaw - one high/the other low, don't they?

I only followed this thread loosely. Sorry if that would've been brought up.
Nice visualization of the current flow.
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Old 5th January 2010, 04:39 PM   #184
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Thanks, Salas.
The picture is much clearer to me now.
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Old 5th January 2010, 04:44 PM   #185
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Quote:
Originally Posted by Joshua_G View Post
Wouldn't electrolytic cap in parallel to the filament improve DC smoothness?
I always do this. In the Mbius heater supply I use a 4.7μF NP electrolytic across the circuit before any dropping resistors, In the Machine supply (with its greater draw and thus lower effective Z), a 10μF. The sonic result is that any residual hum from cathode coupling is now a very soft, rounded sound, with little or no 'buzz' left in it, and so much less conspicuous at any level. I try to keep Xc of the capacitor at least 50 times that of the heater circuit at 60Hz, to make sure the blue smoke stays in the cap.

Aloha,

Poinz
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Old 5th September 2011, 06:02 PM   #186
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Hi Salas,

Wanting to revive the 6v6 line stage, tubes have been aging on their respective boxes, Im gathering some things and wanted to know if you still use it and if you have made some tweaks there.
Better late than never, time is running low.

Ciao, Tony
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Old 6th September 2011, 04:14 AM   #187
Salas is offline Salas  Greece
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I still use it. Resistor anode load for gain, or the bootstrap cathode follower for no gain. The ones you already know in the thread.
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Old 8th September 2011, 03:09 AM   #188
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Thanks for the input....I can see your design has transcended time and this is a good thing for anybody into this hobby.
Someone said that 6v6 round plate tubes sounded better, is this something you agree with?
I let everyone know about my ramblings and sparkles Im about to produce with my unsteady pulse.
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Old 8th September 2011, 03:37 AM   #189
Salas is offline Salas  Greece
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Such anecdotal info comes from using 6V6s in power amplifiers. In our case you would need the quieter ones. This is weird what we do here, using a power tube for a line preamp, changes things. The Tungsol 6V6GT (Russian made reissue) proved both good for vibrations and sonics IMO. Suspend or soft rubber decouple the tubes on a small sub chassis, it pays off. If you have enough gain for your amp in the chain, utilize the bootstrapped cathode follower, much less susceptible to vibrations or for heaters & anodes heating up noises.
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Old 8th September 2011, 04:27 AM   #190
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P.S. Here are some check points for you as for DC bias. Having measured it with enough 6V6GT I can say that the LT Spice model kindly provided by Robert McLean absolutely complies for bias and gain. Most tubes measure ''well near there'', some are spot on. R1 is substituted by the volume pot in the real preamp of course.
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