5f6a bassman rotary switch placement

[maxk]

Hello everyone,

Long time lurker first time poster.

I am building a 5f6a bassman and have a Hoffman output transformer with secondary taps for different speaker impedance, but I do not know where to put the rotary switch.  The easiest solution I came up with was to put the rotary switch where the ground lift switch would normally be, but I’m afraid the distance between the transformer to the lift switch hole, then back to the speaker outputs, would add unwanted noise.  Could I get away with this using shielded cable or does anyone have a better idea?

 There isn’t much room on the back of the chassis, by the speaker jacks and the tube sockets, where I would like to put this thing… My other idea is to put the switch in between the power transformer and the board.  There is plenty of room but that also seems like a strange choice.

Also curious as to opinions on what tubes/ speakers I should use.  Probably going for weber speakers but don’t know which would sound the best.  I have a weber speaker in a 5e3 I built a few years ago and am in love with the thing.

Other misc things about my build (if anyone cares)
Hoffman chassis, choke, board
Kendrick power transformer


Any help is appreciated.

- Max

[bigsbybender]

Noise may be an issue but, at that point, will not be a huge issue. In fact, I doubt you'd have a problem at all. The main places that are noise sensitive, are where the signal is weakest. This would be the preamp section, and effects loop, although poorly designed power supplies can add noise. At the preamp stages, what would have been small noise, then gets picked up and amplified with the rest of the signal.

Since that Ground Switch (Not actually a lift in 1959) is near the power transformer, I can see where you'd have qualms.  I don't think that it is a big deal... For good measure, carefully route your wiring away, perhaps against to the chassis.

My main worry is that with the switch so accessible, some dummy would turn your impedance selector to 2Ohm while you're running an 8Ohm load without you noticing.

Speakers.... are you going 4x10 like the original? Opinions vary greatly in this department. Some would only go with classic style Alnico, like Jensen or Weber. I built a Hoffman 5F6 but did some JTM45 like mods to it.  I have it with 2 Eminence Alnico speakers, and 2 lower end Celestion 10"s. I think I'm going to change to Eminence Patriot/Red Coat.  My thought with the 4X10 is that it gives an advantage to mix and match speakers for the best tone..... on the other hand, when I lift it, I wish I had built a 1x12  

Welcome...I think I lurked for 2-3 years before my first post as well.

j.

[maxk]

Thank you both for the advice.   Somehow it slipped my mind that having an impedance switch easily accessible to prying hands would be a bad idea… I am young enough that a good number of people I have played with are completely clueless with things that seem common knowledge; flipping the on/off and standby switches at the same time, turning on an amp head without a speaker attached, etc…  This is accentuated by the idea that I try to have really cool gear and friends/band mates like to play with it when im not around…  Though paying for a replacement tranny on my 18w marshall clone will teach one a lesson.

I think putting the switch in a speaker jack hole is a great idea… still might be a bit crowded, but should work, and that’s near where the switch would be if I had drilled the chassis myself.

As for speakers.. I want to go the 4x10 route though I still haven’t a clue as to what kind.  As I said before, I really like webers but I have no idea what type would suit my needs.  Having read some strong opinions, which seem to contradict each other, I don’t know what to think.  I have heard ceramics are better than AlNiCo, good AlNiCo are better than mid grade ceramics…   I realize these things are completely up to opinion, but it would be nice to have a push in a certain direction.

My only stipulation is; I would like the speakers to work well with both bass and 6 string guitars.   I am more of a guitar player, but I have a bass and no suitable amp to play it through.  I also think having a decent bass rig is like job security for a guitar player. No offense to serious bassists out there.

[6G6]

Speakers are very subjective.
A lot depends on what you want them to do.
There are a lot of Super Reverbs in the world that have
Alnicos on top and Ceramics on the bottom, to add two different
types of sound and responce together.

If you want to be able to also use it for bass, I'd suggest
a seperate speaker cabinet, with a 15 and a tuned port.
If it was the same size and shape as the 5F6 cab, even
if it ends up being deeper. it'll make a nice stack.
Eminence makes several nice 15s that will do the job.
I like old EVM15Bs, myself.

[bluestone]

It is my understanding that the reason for the 4 seperate RCA speaker jacks is to allow a reduction in the current each wire is carrying to the speakers. To me it kinda makes sense except when you look at the OT wire size...

I have Kendrick Blackframe 10's in mine and love them....

[EL34]

Use one of the rca speaker jack holes for the switch and connect the rotary to one or two 1/4" speaker jacks
Wire all the speakers wire heavy gauge wire and then to a 1/4 plug

There's no need for four speaker jacks

[maxk]

So i'm thinking about getting two weber 10F150T vintage series ceramics and two weber 10A125 vintage series AlNiCos.  Anyone have experience with these or think theres something better out there in the same price range?  Would be nice to get a 15'' cab and make a stack, but by dad offered to do the wood work on this project and I would feel bad asking him to make another cab.  Is there really anything wrong playing a bass through the 4x10 or is the 15'' just better overall... I thought leo fenders intention with the bassman was that a 4x10 had better bass response due to having more speaker surface area.

[dwp]

I've built a few 4X10 Tweed repro Bassman's, a few speaker cocktails, mixing two heavey for bottom, two lite for treble, etc. Aleays think they sound great for a while, but I'll admit it's mostly cause it's my creation, I have to love it. The absolute best sounding 4X10 Tweed Bassman I've had though, hands down, many ears and many raves, was just going with the reproduction of the original four Jensen P-10 R's, whether Italian Jensen or Weber repro, something about the depth, presence, looseness, warmth, four alnico's, not too heavy. my two cents.....