6DN7's

TurbOSquiD77 · 4978

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Offline Doc B.

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Reply #15 on: April 12, 2017, 04:36:36 AM
Can I borrow the drill bit you use to make an octal hole into a seven pin mini?

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline TurbOSquiD77

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Reply #16 on: April 15, 2017, 11:58:32 AM
Update:

Fits great :)
I'm confident that I've got the pinout change correct, but I'm unsure of heater wiring. Looking at S.E.X. 2.1 vs. the 3.0 I'm having a difficult time understanding how to wire the heaters.

I think* that the 6DN7 should be connected as follows with the 3.0:

6FJ7                      6DN7
Pin 1     -Heater Black-       Pin 8
Pin 2          -No-
Pin 3     -Grid Section 2-   Pin 1
Pin 4          -No-
Pin 5     -Plate Section 2-  Pin 2
Pin 6          -No-
Pin 7     -Cathode Sec. 2-  Pin 3
Pin 8          -No-
Pin 9     -Cathode Sec. 1-  Pin 6
Pin 10   -Grid Sec. 1-        Pin 4
Pin 11   -Plate Sec. 1-       Pin 5
Pin 12   -Heater Red-         Pin 7


Although, in each kit the heaters are wired differently. 2.1 same connections, 3.0 opposite.

2.1:
Red - Pin 8
Black - Pin 7
Both tubes.

3.0:
Red - Pin A12, B1
Black - Pin A1, B12

I see there is a 270 ohm resistor (terminals 1 and 15) that run to pin 12 on each channel, which is why red/black heater connections need to be opposite correct?

Could I please ask for advice on connections with the 6DN7? I would absolutely greatly appreciate the input from anyone and everyone. I would try it out, but I'm unsure if making a heater wiring error would result in very bad things.  :)

I'm also curious if I can implement the 220ohm carbon film resistor by attaching close on pin 4, and an isolated terminal post (so it does not make ground contact), and attach the orange and white striped wire from the bottom center terminal of the attenuator to that post as well. This would mimick what was pin 8 on the 6FJ7.

Thank you!

-T
« Last Edit: April 15, 2017, 01:30:01 PM by TurbOSquiD77 »



Offline Paul Birkeland

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Reply #17 on: April 15, 2017, 01:29:35 PM
I see there is a 270 ohm resistor (terminals 1 and 15) that run to pin 12 on each channel, which is why red/black heater connections need to be opposite correct?
Yes.
-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline TurbOSquiD77

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Reply #18 on: April 15, 2017, 01:30:41 PM
Got it! Thanks much.



Offline fullheadofnothing

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Reply #19 on: April 15, 2017, 02:26:35 PM
The question would be - why? They are the same tube in a different bottle.
You could on-sell the 6DN7's for no loss & buy yourself probably half a dozen 6FJ7's.

This is the correct answer.

Joshua Harris

I Write the Manuals That Make The Whole World Sing
Kit Packer Emeritus


Offline TurbOSquiD77

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Reply #20 on: April 15, 2017, 03:20:43 PM
I completely agree, and I think it makes much more sense than the road I've chosen.
However, I'd still like to try, and see what I can learn along the way.
Crafting an adapter for 6FJ7's will be interesting. I can always revert and primarily run 6FJ7's in the future.  :)



Offline TurbOSquiD77

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Reply #21 on: April 18, 2017, 06:18:14 AM
Did it! I think so anyways....

Resistance tests passed.
Voltage tests passed (I think/please advise).

Stock/6FJ7
Terminal Voltage (DC)

2      86.1
3      17.58
4      55-65mv
5      0
6      388
7      403
10      382
16      76.1
17      17.14
18      90mv
19      0
20      387
21      404
24      383
H2/H5      3.28/3.28
H4/H7      -3.11/-3.11


Stock/6DN7
Terminal Voltage (DC)

2      74.7
3      18.22
4              150-175mv
5      .1mv
6      384
7      402
10      379
16      70.5
17      18
18                110-125mv
19      .1mv
20      384
21      401
24      379
H2/H5      3.29/3.28
H4/H7      -3.12/-3.11

I've bolded what I'm concerned with, but do understand the +/- 10% rule. Just posting my voltages for a peace of mind :)

Whatcha guys think? Haven't had a chance to listen yet, but will tonight. I listened with the 6FJ7's for quite a while, but terminals 4/17 were of lower voltage than with the 6DN7 now.

Thanks!

-T

edit:
Found this thread - http://bottlehead.com/smf/index.php?topic=9851.0
I think I'm good  8)
« Last Edit: April 18, 2017, 03:54:44 PM by TurbOSquiD77 »