Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: uki on May 05, 2015, 06:43:42 am
-
I'm building a 6G8, from the schematic and layout , http://el34world.com/charts/Schematics/ (http://el34world.com/charts/Schematics/) ... IN_6G8.pdf
I got all other parts but the resistors and capacitors, the following list is what I could figure out about resistors and capacitors.
I would like to know if this list is correct, that would be very much appreciated, if there is something missing or wrong please let me know, I'll update the list as information comes by, this may help others seeking for this same information.
Could anyone tell please, is this list correct? :help:
Capacitors list:
* 400v minimum unless specified
Film/Foil
0.03 µF/MFD (30 nF) * 1x
0.05 (0.047) µF/MFD (50 nF (47nF) * x8
0.1 µF/MFD (100 nF) * 2x
0.1 µF 200v (100 nF) 2x
Electrolitic:
Circuit Board
50 µF - 25v 2x
25 µF - 25v 2x
4 µF - 25v 1x
Bias Rectifier
8 µF - 150v 2x
Filter Pack
20 µF - 600v 7x
Ceramic/Mica:
0.001 µF/MFD (1 nF) * 1x Ceramic
0.01 µF (10 nF) * 4x "
0.02 µF (20 nF) * 2x "
0.005 (0.0047) µF/MFD (5 nF (4.7nF)) * 1x Ceramic
47 pF/MMFD * 1x Mica / Ceramic
on Potentiometers:
Vibrato/Presence
0.1 µF (100 nF) - 200v - 2x Film/Foil?
Bass
0.01 µF (10 nF) - * 2x Film/Foil? On bass pots see image link: http://bb.steelguitarforum.com/userpix1205/2629_Chassis_010_2.jpg (http://bb.steelguitarforum.com/userpix1205/2629_Chassis_010_2.jpg)
0.001 µF (1 nF) - * 2x
Treble
0.005 (0.0047) µF (5 nF (4.7nF)) - * 2x
0.00025 µF (0.25 nF - 250pF) - * 3x one of them is listed in the layout, as 250 MMF
Ground Switch cap:
0.05µF - 600v type?
Resistors list:
820Ω - 2x
1500Ω(1.5k) - 6x
2700Ω(2.7k) - 2x
4700Ω (4.7k) - 3x
4700Ω (4.7k) - 1x (Filter pack, this one doesn't appear in the layout)
6800Ω (6.8k) - 1x
10k - 2x
22k - 1x
56k - 3x
56k - 1x (Filter pack, this one doesn't appear in the layout)
68k - 4x
100k - 5x
180k - 1x
220k - 2x
470k - 4x
82k 5% - 1x
100k 5% - 3x (In the layout 2 of them are missing the 5% detail)
220k 5% - 2x
27k 1w - 2x (Filter pack, these doesn't appear in the layout)
470Ω 1w - 4x
1m - 12x
10m - 1x
Thank you in advance!
updated 18/Jun/2015
-
470k 1w - 4x
That should be 470Ω 1W - 4X
That .0002µF cap on the NOR channel Treble pot is likely to be 250pF. (same as on other channel treble pot)
I didn't look at every item on your list.
-
470k 1w - 4x
That should be 470Ω 1W - 4X
That .0002µF cap on the NOR channel Treble pot is likely to be 250pF. (same as on other channel treble pot)
I didn't look at every item on your list.
Thanks for the hint about the resistors on the power tubes.
About the caps in the treble pots both layout and schematic shows 2 different one on each treble pot, so then it is probably a miss print? All are 250pF ?
There is a 3nd cap like this but doesn't appear in the layout, only in the schematic,
Here where the missing one is at, hopefully this is understandable enough:
It is at the middle of the schematic a bit bellow and to the left of the 7025. This one doesn't appear in the layout.
Main post updated.
-
The sound difference in that spot between a 250pF and 200pF cap won't be much. They don't cost much, buy both and see which 1 you like better.
The 3rd 250pF cap is in the layout, but in the layout it's listed as 250mmF (micro micro) it's the old way of saying pF.
Also .005 and .05 caps are now .0047 and .047 and .002 caps are .0022.
Brad :icon_biggrin:
-
The sound difference in that spot between a 250pF and 200pF cap won't be much.
Which one will be more bright?
The 3rd 250pF cap is in the layout, but in the layout it's listed as 250mmF (micro micro) it's the old way of saying pF.
Also .005 and .05 caps are now .0047 and .047 and .002 caps are .0022.
Thanks , great info, I didn't know that.
main post updated.
-
Which one will be more bright?
The smaller 1, but there won't be much difference.
Brad :icon_biggrin:
-
The smaller 1, but there won't be much difference.
Thanks, handy info !
In the top of caps list what type those can be? I don't have much clue about that.
Im checking this list before buying it, because I can only buy it online those caps and resistor don't exist where I live, South America.
There are very few people that build tube amps here as well.
-
Major updated on main post !!
-
Time to make your first order!
-
Time to make your first order!
I have everything else already, the only parts missing are the caps and resistors. Do you think the list is correct ?! Im not sure what type is the ground switch cap.
Is there a problem if resistor used are 5% tolerance instead of 10% ?
Is there a problem if resistor used are 20% tolerance instead of 10% ?
-
Im not sure what type is the ground switch cap.
You won't need that cap because your going to be using a 3 wire power cord with a dedicated safety ground wire.
With that power cord the ground switch won't do anything anyway. A lot of guys that have a pre punched chassis put the switch in for looks but don't wire it up. Or they make it a standby switch on amps that don't have them.
Is there a problem if resistor used are 5% tolerance instead of 10% ?
Is there a problem if resistor used are 20% tolerance instead of 10% ?
Fender and the others, back in the 50's and 60's, used 20% for all most all R's. Only a few R's were noted on their schematics for 5%.
Now a days 5%, 2% and 1% are cheap and easy to get a hold of.
Brad :icon_biggrin:
-
You won't need that cap because your going to be using a 3 wire power cord with a dedicated safety ground wire.
With that power cord the ground switch won't do anything anyway.
Indeed I have forgot about that detail and I do already have the 3 pins socket.
Fender and the others, back in the 50's and 60's, used 20% for all most all R's. Only a few R's were noted on their schematics for 5%.
Thanks !
I got 5 0.01µF - 1.6kv film/foil caps, can those be used with this big voltage ? They looks like NOS stuff.
Here some pics:
-
I got 5 0.01µF - 1.6kv film/foil caps, can those be used with this big voltage ? They looks like NOS stuff.
Maybe.
As long as their still good and don't leak dcv and if they'll fit? The higher the voltage rating on caps the larger their size.
Then how do they sound? Malory 150's, orange drops and other caps are well documented in use as how they sound with many guys using them.
Brad :icon_biggrin:
-
I got 5 0.01µF - 1.6kv film/foil caps, can those be used with this big voltage ? They looks like NOS stuff.
As long as their still good and don't leak dcv and if they'll fit? The higher the voltage rating on caps the larger their size.
The caps looks good, no leaking or anything bad, haven't been used they were probably just sitting in a shelf.
I havent cut yet the circuit board, I'm waiting for the components before start doing it, to make sure things will all fit, since the amp cabinet have custom dimensions all have to be well mesured.
-
Deleted
-
Regarding those caps, Willabe is talking about leaking DC voltage.
Thanks for clarifing that detail ! Indeed I did bought new ones just in case.
-
Main post updated, couple resistors missing in the list. Notes added.
In the filter pack there are 4 resistors that doesn't appear in the layout.
1x - 56k , 1x - 4700(4.7k) , 2x - 27k 1w.
Cheers