10,000 circuit

[neikeel]

One of the last 67 (contimued into 68):
http://amparchives.com/album/Marshall/1 ... /b5_3.html
regarding Screens Filter can use either 100uF or 32uf true?
and then I see a capacitor as close to cathode resistor and 'its value?, and I have to use it' cause you do not see on other models

Yes you can use 100uF x2 (=50uF) for mains and for screens, like later amps, loses some of tactile nature of these amps but caan help a little with ghosting (if you want that just build 69 spec superbass)

The other cap is over V2a and it typically 330uF and is a mod. used by some VH tone chasers, used to boost all frequencies. IMO adds mud and I do not like it at all but each to his own

[astor 1]

however, I can see in the photos that many of 67 Filter Screens on using 32/32, so I could use either 32/32 or 100/100 right? Bright cap "that has value? and the choke is fine for 3h or 5h? many thanks for the help

[neikeel]

however, I can see in the photos that many of 67 Filter Screens on using 32/32, so I could use either 32/32 or 100/100 right? Bright cap "that has value? and the choke is fine for 3h or 5h? many thanks for the help

Yes 32+32 (=16uF) is normal screens for that era (Pi cap on chassis top is typically 32uF (500v single can) to 48uF (dual 32uF+16uF with both elements in parallel).

Choke is a 3H Drake 354-114 which has a DCR of a little over 100ohms and rating of 250mA. George used to sell these but I think George M and Brian Wallace now only sell the Dagnall version (same specs but on plastic bobbin, the C1999). The odd amp did escape with the earlier RS 20H 690ohm lower rated choke in 67 as well.

[astor 1]

to build a version of lead should add only the bright cap on the first volume
true?, and how and 'the value of the bright cap? version of the super lead and super bass
changes only the addition or not of that capacitor right?
thanks again for the valuable information

[neikeel]

to build a version of lead should add only the bright cap on the first volume
true?, and how and 'the value of the bright cap? version of the super lead and super bass
changes only the addition or not of that capacitor right?
thanks again for the valuable information

The value of the bright cap is best tuned to your amp once it is built. Most sound best with a 100pF cap, which gives a little sparkle at lower volumes and some clean headroom without sounding too dull. 500pF often sounds spiky with a 1meg volume pot at mid volumes but some people like that. By the time the cap is 1,000pF it is passing a wider frequency spectrum and is starting to give more of a gain boost at lower volumes. A 5,000pF cap is a definite low volume gain boost rather than 'bright cap' but you lose clean headroom (most of the gain kicks in at 2 or 3 on the sweep of the volume pot) so you might not like it.

[astor 1]

since it's' difficult to find capacitors da32uf, I could use on Filter Screens
capacitors f / t from 30uf, or of 33uF?

[neikeel]

since it's' difficult to find capacitors da32uf, I could use on Filter Screens
capacitors f / t from 30uf, or of 33uF?

IMO either F&T 33 or RIFA 33

[astor 1]

30uf but I use them? george I saw that on the 12xxxx series uses

[Roe]

the bc and rifa 33uf caps are preferable to the f&t 30uf caps