Choke loading Anodes.
#181
Yep, thats it.
He hosted the image on photobucket and then inserted a link to the image.
He hosted the image on photobucket and then inserted a link to the image.
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#183
Ask a daft question but is it really necessary to have such ee-norm-ouse value inductors for the first stage anodes?
Ah wait a minute, probs because 400H @ 50 Hz = 128 kilohms
Blinking flip ...
#
Ah wait a minute, probs because 400H @ 50 Hz = 128 kilohms
Blinking flip ...
#
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
#184
Yep, you are forming a RL high pass filter between the ra of the valve and the inductor, so for the first triode in a 6em7 with a ra of 40k, the -3dB with 400H will be 16Hz
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#185
Yup, as I found out when I just stuck one 200H choke in I lost bass. 2 in series brings it back but 'EM' doesn't seem to be an ideal candidate, that led to this thread actually didn't it, good lord! We're still on topic!Nick wrote:Yep, you are forming a RL high pass filter between the ra of the valve and the inductor, so for the first triode in a 6em7 with a ra of 40k, the -3dB with 400H will be 16Hz
Now then, 6DN7's ra is much lower isn't it at 9K. Thats going to affect the -3dB point I'm guessing.
IIRC from earlier in this thread the formula for working out the 3dB point of RC networks was f-3db = 1 / (2 x PI x C x R).
What one formula would you use for working out f-3dB when ra and inductance is involved Nick?
Back to DRD'ing. Does DN or EM lend itself better to to DRD topology?
If its raining over the weekend I could try that cct.
DTB
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#186
Aha - I see now, I wondered why there were 4 ways.Nick wrote:Yep, thats it.
He hosted the image on photobucket and then inserted a link to the image.
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Edmund Burke
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#187
RL formula
f-3 = R / ( 2 * Pi * L )
Where in this case R = ra, and L is the size of the choke in Henry,
f-3 = R / ( 2 * Pi * L )
Where in this case R = ra, and L is the size of the choke in Henry,
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#188
Thanks Nick, so using that formula with 6DN7's 1st triode and 400H load I calculated 3.58Hz is the f-3dB point.
...and 'cosI've got a calculator in my hand ... Halving the inductance to 200H gives 7.16Hz.
Conclusion, with 6DN7 I don't really need 400H do I? 200H would do really.
Using 6EM7 using 1 200H choke gives a f-3dB of 31.8Hz and 2 chokes gives 15.9Hz.
Hmmmm.
DTB
...and 'cosI've got a calculator in my hand ... Halving the inductance to 200H gives 7.16Hz.
Conclusion, with 6DN7 I don't really need 400H do I? 200H would do really.
Using 6EM7 using 1 200H choke gives a f-3dB of 31.8Hz and 2 chokes gives 15.9Hz.
Hmmmm.
DTB
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#190
Arf, I said Hmmmm not HumNick wrote:Yep, it can, all those are well above 100hzHmmmm.
That DRD cct Phil has drawn be OK for 6DN7 and 6EM7 Nick?
DTB
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#191
No 6em7, may need some values changing for t'other one. Should be doable though. Start with the op points you need and go from there.
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#192
How about that.Dave the bass wrote:Conclusion, with 6DN7 I don't really need 400H do I? 200H would do really.
Using 6EM7 using 1 200H choke gives a f-3dB of 31.8Hz and 2 chokes gives 15.9Hz.
Hmmmm.
DTB
Nothing is without change ..Dave the bass wrote:good lord! We're still on topic!
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#193
YMMV Dave but I found that lowering the anode choke F-3 on my 26 pre from 8Hz to 4Hz made quite a difference in filling the bottom end out.Dave the bass wrote:Thanks Nick, so using that formula with 6DN7's 1st triode and 400H load I calculated 3.58Hz is the f-3dB point.
...and 'cosI've got a calculator in my hand ... Halving the inductance to 200H gives 7.16Hz.
Conclusion, with 6DN7 I don't really need 400H do I? 200H would do really.
Using 6EM7 using 1 200H choke gives a f-3dB of 31.8Hz and 2 chokes gives 15.9Hz.
Hmmmm.
DTB
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#194
Ooooerrr, thanks Simon.simon wrote: YMMV Dave but I found that lowering the anode choke F-3 on my 26 pre from 8Hz to 4Hz made quite a difference in filling the bottom end out.
DTB
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#195
So are we saying that the anode chokes for a 6DN7 should be 400H (2 x 200H ) like DTB currently uses or would one 200H be enough.
I was going to order some anode chokes and need to know how many.
I was going to order some anode chokes and need to know how many.
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)