the CM choke has 4 leads and can be reconnected as a differential choke, you gave me another idea, will try that in future builds....
i have been told also by a friend who makes ferrite torroid CM, and some hobbyists are getting those from him and using CM chokes on the filaments....will try that too...
the CM choke has 4 leads and can be reconnected as a differential choke, you gave me another idea, will try that in future builds....
i have been told also by a friend who makes ferrite torroid CM, and some hobbyists are getting those from him and using CM chokes on the filaments....will try that too...
One great advantage of this "common mode" approach is, no one would consider to solder the common wire to the wrong place, near the negative output of the rectifier, then complain on SS diodes that sound bad.
the power traffo i used has a center leg of 0.75inch and stacked to about 1 inch, 10turns per volt, 220volt primary, secondaries are 110volts and 6.9volts...
B+ is about 130 volts when operating, currents are about 10mA per triode...
output impedance Zout is in to 300 ohm range.....
the input volume control is in fact a 100k audio taper alps pot, but you can use any where from 20k to 250k to suit your taste...
here is a list of tubes that will work in my preamp:
6922WA, CCA, CV10320, CV2492, CV2493, CV8065, E88CC, E88CC01, ECC868, 6DJ8, CV5358, ECC88, 7DJ8, CV10403, PCC88, UCC88, 6N1P, E188CC,7308, CV5231, CV5354, E288CC, 8223, 6R-RH2, 6R-RH8...
sory to edit out all other tubes, but I have 6N1p, and tempted to try it for my hiend bass guitar preamp
CCDA ? I know it means constant current draw, but whats the reason for it ?
but all I see different is a diode to the cathode output, bootstrapping or whatevr it does
is that really all ?
the diode is fixed biasing, it can be replaced by a resistor instead....i did not hear any difference either way...more info here....CCDA: constant-current-draw amplifier
Hi Tony!
Which of these tube provides the best sound for your taste?
Instead of two series connected diodes 1N4004 can eat two set of resistors connected in series by 82ohm (2x82ohm).
I'll do with the new power semiconductor devices.
For my CD-player Technics who resistors that connect to the preamp input?
If you do some measurements of the preamplifier Tony post them here ..
Thank you for your cooperation
ahh, I see, its like a balance act between input anode and output cathode, using equal resistors
you omitted one resistor in output cathode ?
edit
quote(Broskie), resistor R7 (the extra cathode resistor) is optional, although highly recommended, as its inclusion buffers the cathode follower’s output from heavy capacitive loads and increases the cathode follower’s linearity, but at the cost of increased output impedance. Attachments
DHT Rob uses the other optional method, coupling output cathode to input tube cathode
http://www.diyaudio.com/forums/tubes-valves/216285-ccda-dissimilar-triode-preamp.html
but when using two different tubes, will the CCDA work as intended ?
http://www.diyaudio.com/forums/tubes-valves/216285-ccda-dissimilar-triode-preamp.html
but when using two different tubes, will the CCDA work as intended ?
Attachments
Bear in mind that only a CM-mode choke will offer DC current cancellation. The right reason to use a CM choke is that you have CM noise on big currents - a CM choke can be much smaller and cheaper than a pair of normal chokes which would cope with the big currents.Tony said:
There are other ways to wire a bifilar-wound choke, but you have to think where the currents and signals go; which get blocked, which get passed, which get cancelled in the core.
DHT Rob uses the other optional method, coupling output cathode to input tube cathode
http://www.diyaudio.com/forums/tubes-valves/216285-ccda-dissimilar-triode-preamp.html
but when using two different tubes, will the CCDA work as intended ?
Why would you need positive feedback on DC and low frequencies?
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