|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
76.90.39.24
In Reply to: RE: Smeared? posted by gusser on December 12, 2016 at 11:57:40
"But I have to ask if the circuit parameters have been adjusted for the good old LCR changes the additional tube section makes? because that's most likely what you are hearing."
When paralleling the two triodes of a 6sn7 does the Miller capacitance go up vs. one triode?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Follow Ups:
x
.
Have Fun and Enjoy the Music
"Still Working the Problem"
It goes up but how significant it is depends on the rest of the system.
The preceding stage in my case has output impedance of about 47 ohms and I use a 470 ohm grid stopper. A paralleled 6SN7 has about 8pF of plate to grid capacitance and in the case of using a CCS, a mu of about 20, so about 168pF miller.
I say "about" because the two sections of a 6SN7 don't have the same input capacitance and even with a CCS the mu can vary tube to tube.
So yes it affects the FR but whether it makes a difference is up to the builder and the application.
" So yes it affects the FR but whether it makes a difference is up to the builder and the application."Yes, that's why I brought it up.
If the drive impedance was high and someone switched to parallel from single and noticed a difference in sound, the sound difference could be do to that.
"The preceding stage in my case has output impedance of about 47 ohms"
but not in your case.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 12/13/16 12/13/16
If I were starting an amp from scratch, I might not opt for a paralleled driver. If I were modding an existing amp, I would look at how much effort is is to change the the driver to something completely different. Also, I have a lot of tubes sitting around here that need a home and that could influence the choice. Starting with a blank page, I am liking the 6EJ7 recently. Nice little pentode that sounds good run as is or triode connected.
In the case of the offending 300B amp mentioned in this thread, it started with a 6SJ7 driver, which sucked, so I tried a variety of other octal tubes so I could use the same size socket.
I will say this, a paralleled driver sounds better to me than a cascade whether DC or cap coupled. The extra stage takes more away than the paralleled version adds.
IME, the EL84 is a *VERY* fine signal tube. Very fine indeed...:) High ratio plate/g2 current. Good gm at low g2 voltages( around 100V ), and with a variable g2 voltage responds very well to tuning the tube characteristics to match a chosen plate load.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
I agree. I first was made aware of the EL84 as a driver by an article by Thorsten Loesch. I just copied his version with a 300B and it absolutely is a great driver. It helps that I've got lots of them as well.
I would be very interested in how your latest amps are designed Douglas. You've had some great ideas in the past and I feel that they align with my view more often than not. I haven't done a PP amp for years but I'm thinking that I would like to apply some of the things I've learned to one now. The SE thing is a bit of a dead end for anyone that likes to listen to music at more than background volumes or that enjoys realistic bass. That should stir up the natives:)
hey-Hey!!!,
Another liddle power tube I plan to examine is the 2E24. It is a DH number about the size of a 6V6 and given the performances of other DH tubes ought to work quite well.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: