jchrisf
Well-known member
Great explanation.. that's easy to understand. Would the Marshall Stereo jacks always be Series/Parallel in every switch position/jack since there is 4 wires going to it?
FourT6and2
Well-known member
I'm not sure I agree with this. Are you saying that scenario A is electrically different from scenario B? Are "Series/Parallel" and "Parallel/Series" simply terms for how to wire the jack and not actually related to whether each speaker in a pair is in series or parallel or whether that pair is in series or parallel with the other?
In Scenario B, the wires were simply moved off the jack, to the speaker solder tab instead. But both scenarios are two paralleled pairs (at the jack), whose speakers are wired in series. Speakers 1 and 2 are in series. Speakers 3 and 4 are in series. And both sets are paralleled "at the jack". But in B, the jack connection is being made at the speaker terminal. Electrically, they are identical. So I'm not sure why one would be Series/Parallell and the other Parallel/Series when nothing has changed electrically...
Scenario B simply uses slightly less wire, it's quicker to install, and it doesn't crowd the jack as much. I'm not too concerned with what Marshall did or didn't do.
Last edited:
FourT6and2
Well-known member
I popped a handle off to have a look. Pretty clean build quality. The only thing that I question is the lack of washers on the speaker mounting nuts/bolts. Should I leave them as is or install some washers. But if the nuts were overtightened by Mesa, the damage has already been done.
Scumback Speakers
Well-known member
@FourT6and2
Dave Friedmand & I (along with Roy Blankenship & George Lynch) went through the both wiring setups 16 years ago. We felt the wiring with four wires at the jack (S/P) was more vintage sounding, more bass, and bluesier. P/S was more modern sounding and had a slightly more aggressive tone in the mids.
Keep in mind this a "subtle" difference, so you might need dog ears like Dave & I to hear it.
Hope that helps!
Jim
Dave Friedmand & I (along with Roy Blankenship & George Lynch) went through the both wiring setups 16 years ago. We felt the wiring with four wires at the jack (S/P) was more vintage sounding, more bass, and bluesier. P/S was more modern sounding and had a slightly more aggressive tone in the mids.
Keep in mind this a "subtle" difference, so you might need dog ears like Dave & I to hear it.
Hope that helps!
Jim
FourT6and2
Well-known member
@Scumback Speakers Truly, I'm not trying to be difficult or argumentative for no reason. But no... that doesn't help. Because nothing actually changes by moving a wire from the jack to the speaker solder lug. You haven't changed the wiring at all—electrically. You've simply moved a connection from point A to point B without changing the circuit. It's like moving a ground wire on potentiometer from the back of the pot to the side of the pot—nothing has changed at all.
Moving these wires off the jack doesn't change whether the speakers or pairs are in series or parallel or series/parallel or parallel/series. Zero change.
Let's pretend the speaker wires have no insulation. They're bare wire. You can walk the jack connections down the length of the other pair's wires from jack to speaker lug. Solder those connections anywhere, at any point along that wire. There is absolutely ZERO difference between any of these. Solder them at the jack, or 3 inches from the jack, or 6 inches from the jack, or 8 inches from the jack, or right at the speaker itself. Zero difference...
Last edited:
thegame
Well-known member
@FourT6and2 , just use this diagram for S/P. I prefer this because I don’t like summing both +/- connections at the jack. Here they’re just summing at the first + and - on the speaker terminals. Anyway, this sounds and feels fairly different than the “Bogner P/S way” you linked previously in this thread. There is no right or wrong here as some amp/speaker combinations are better with one or the other so experimentation is vital.
Klauth
Active member
yes. I do.
Klauth
Active member
Last edited:
FourT6and2
Well-known member
Yes... that one is different. All I was getting at before is that some conflate moving a wire here or there with changing the actual electrical arrangement of the speakers. When in reality, nothing has changed with respect to series vs parallel or series/parallel vs parallel/series. You need to actually change how the speakers are connected in order to do that. But yes, this diagram shows a different arrangement compared to the others (like Bogner's method).
H
harddriver
Well-known member
That configuration is the series/parallel used in Tom Mitchell's (How to Service Your Own Tube amp) wiring for a 4x12. With this configuration in a 16 ohm 4x12 cabinet if one speaker voice coil blows, three speakers will continue to operate and it will retain a usable impedance load of 24 ohms(which is usable during a live show) on the amp so the head doesn't blow power tubes or damage the output transformer according to Tom Mitchell.
This is how I have been wiring all my 4x12's since the 90's when I got his book and have been satisfied with how it works. YMMV.
311boogieman
Well-known member
I'm not the expert in the room but that sounds right to me too. We had a big thread on this last year I think and it concluded the same way as it relates to total impedance.
dave74
Well-known member
Bumping this to see if anyone has ever tried "tuning" an OS cab by means of internal air-space displacement. (???)
Klauth
Active member
Yes...extensively. and it is worth it if you have the time, resource, knowhow and interest but, is too involved to discuss acoustic engineering on a chat room.
mnemonic
Well-known member
Naming conventions are confusing me the most here, this diagram is the same as the ‘parallel series’ in the below diagram posted by FourT6and2 on page 3
the4thlast1
Well-known member
Yes the one on the left is the same as the one in the attached link. In my opinion that wiring yields the best tone after trying both in the same cab. There are only two ways to wire a 4x12. Either you Parallel the pairs together or you Series the pairs together. As FourT6and2 mentioned any other differences are just moving around where the wires make contact which sometimes even unessesarily adds more wire. As an electrician that part seems silly to me, but I'm not an audio expert. If you change the placement of where you make contact I dont see how that effects sound in any way other than possibly adding or removing a very tiny amount of resistance.
thegame
Well-known member
I agree on the confusing aspect. Technically the L and R pairs are joined at the top pair of speakers here (assuming the jack is at the top) while in the diagram I linked it’s at the bottom pair.
N
Nigel
Well-known member
Yeah man both diagrams are series parallel. The second one is the Aiken way with one set of pod/neg moved to speaker tabs instead of the jack as stated above.
FYI: even Mesa’s diagrams on their ZenDesk were wrong! Ha! What follies all in the name of tone.
Scumback Speakers
Well-known member
@FourT6and2,
I'm pretty sure the difference I'm talking about is feel, and how the speaker responds to different wiring layouts. Both of my 4x12 diagrams have the same final ohm reading, so electrically they both get to about 14 ohms for a 412 with 16 ohm speakers. But there is a difference in the speaker response that can be heard. Or do you think Roy, George, Dave & I can't hear?
I'm pretty sure the difference I'm talking about is feel, and how the speaker responds to different wiring layouts. Both of my 4x12 diagrams have the same final ohm reading, so electrically they both get to about 14 ohms for a 412 with 16 ohm speakers. But there is a difference in the speaker response that can be heard. Or do you think Roy, George, Dave & I can't hear?
dave74
Well-known member
Up until recently, all my 4x12s have been Bogner. I've really never used anything else. But now I have this Mesa and I have a Hiwatt on the way. I knew Marshall and some others did it differently, but whenever I wired or re-wired a 4x12, I just did what I saw in my Bogner cabs because it uses less wire, it's simpler, and it's faster.
I mean, can it get easier than this? Two parallel pairs of speakers, each wired in series. No crowded terminals anywhere. No mass of wires to try to trace and follow.
I've only rewired two 412 cabs ever, and this is how I did both of them solely for the sake of simplicity. My reference was the series-parallel scheme from the Stew-Mac website.
FourT6and2
Well-known member
Exactly. You get it.
