4x12 Series-Parallel / Parallel-Series Wiring

[rgorke]

Is there any real difference in these two wiring methods? They appear to end with the same total load.

http://www.soundcitysite.com/sc_webpage ... rallel.pdf

http://www.soundcitysite.com/sc_webpage ... series.pdf

[shakti]

Soundwise, there is a very subtle difference in my experience. When you run them in parallell at the jack, you essentially have two pairs of speakers in series. This tends to make it slightly more raucous/aggressive sounding. When you wire them in series at the jack, you essentially have two pairs of speakers in parallell. This gives a slightly tighter, more rounded sound.

But bear in mind that I couldn't do this as a true A/B test, and it is subtle...but that's what I heard when I tried both ways of wiring.

[rgorke]

Thanks,

I just got 2 - 4x12 cabinets from a friend and he wasn't sure how he had them wired. Maybe I will wire one each way and see which way I like it.

[62sg]

Some 'hear' the par/ser as being slightly darker.
Here's what Ted Weber had to say when I posed this ? a long time ago:


From our "Let's Talk Speakers Q & A" on our website:

connecting two speakers in parallel is an old trick to smooth out speaker response and enhance the damping of either speaker. HIFI designers took it one step further by connecting two speakers of different sizes in parallel. A speaker has a large impedance increase at its fundamental resonance, and depending on the installation, this can cause the speaker to sound boomy or out of control. By connecting two speakers in parallel, particularly two speakers of different sizes with different resonant frequencies, each speaker will tend to quench or dampen the boominess of the other. Since no two speakers are exactly alike, even two of the same size, that damping will occur, however slight, for any speakers connected in parallel. For speakers connected in series, there appears to be less control, and more of what is called 'back EMF' from the speakers fed back into the output circuit. While that seems rather chaotic, many players prefer the series connection, as it gives them a more textured tone, enhanced breakup, and overall a more desireable tone for guitar work. It's totally subjective, of course, and many factors affect the end result, such as voice coil size, gap energy, closed back/open back, output circuit damping, etc. The best thing to do, in my opinion, is try both arrangements since you have the luxury of impedance tap selection, and go with the configuration you like the best.

[89custom]

If you look at the schematic, it is easy to wire a "switch" to switch between one or the other...I ran a temporary switch with the wires comming out through one of the side handle bolt holes...very quick and easy that way to compare them.

[bruce]

May I ask a question on this matter towards the experts, (Scumback Jim and 62sg)..?

Which do you prefer, Series/Parallel OR Parallel/Series and why?

I'd like to know the pluses and minuses (+,-) (no pun intended), of tone, efficiency, and whatever else you care to comment on.

Thanks!

[shakti]

The advantage of wiring them in series at the jack, then parallell, is that if one speaker blows, the other 3 will all work. When you wire them in parallell at the jack, if one speaker blows, the other one in that pair of speakers will not work. This puts a heavier load on the other pair, plus you are now left with a cab with twice the original impedance, which may be heavy on the output transformer.

However, with Marshalls and Celestions, at least, I prefer the latter wiring scheme, which seems to be the standard wiring scheme in Marshall cabs, at least in the late 60s.

[Scumback Speakers]

May I ask a question on this matter towards the experts, (Scumback Jim and 62sg)..?

Which do you prefer, Series/Parallel OR Parallel/Series and why?

I'd like to know the pluses and minuses (+,-) (no pun intended), of tone, efficiency, and whatever else you care to comment on.

Thanks!

My standard 4x12 wiring is the same as Marshall used (mostly) in the 60's and 70's, which is this diagram:


It's the same as this one: http://southbayampworks.com/wiring/4x12%20wirserpa.gif

While the other wiring scheme is electrically (from what I'm told) identical, if you have the proper speakers in your cab, you won't need it, unless you just put too much power to the cab (the old 100 watt Plexi into 4 25 watt M's scenario again) and blew the first one in the series.

This happened many times due to folks not paying attention in the old days. I personally have never had a failure using two 4x12's with 25's or 30's with a 100 watt amp, with one cab with four 65 watt speakers, or with one 100 watt cab with a 50 watt amp.

But this other wiring scheme may work just fine, but I haven't tried it out and A/B compared it with the same cab/cloth/speakers and amp yet.

[rgorke]

Jim,

Is this the same result as your wiring?

[Scumback Speakers]

Jim,

Is this the same result as your wiring?

Beats me! LOL I'd have to wire up a cab and try it. Then of course, I'd have to have identical cabs to A/B with the wiring being the only difference to say what impact it had.

Electrically, I guess they're both 16 ohms. Sonically it's anyone's guess.

[rgorke]

Jim,

Is this the same result as your wiring?

Beats me! LOL I'd have to wire up a cab and try it. Then of course, I'd have to have identical cabs to A/B with the wiring being the only difference to say what impact it had.

Electrically, I guess they're both 16 ohms. Sonically it's anyone's guess.

Sorry, I meant "electrically" e.g. adding up to 16 ohms and you answered my question. I suppose I need to be more specific.

[Scumback Speakers]

Sorry, I meant "electrically" e.g. adding up to 16 ohms and you answered my question. I suppose I need to be more specific.

No worries! Since I come from a computer field for my previous work, I tend to be "specific" and in lieu of someone being specific, I present all of the options to be considered.

You clarified it, so no problema!

[shakti]

Jim,

Is this the same result as your wiring?

Like Jim said, electrically it's the same, but soundwise I've found there to be a very, very subtle difference.

The wiring scheme that Jim posted is the one I refer to as "parallell at the jack". I prefer to specify it like that since series/parallell only means that...you don't know where it's wired series, and where it's wired parallell. In that scheme, you can view the speakers as two pairs, where the left ones are wired in series, the right ones are wired in series, then those two pairs are wired in parallell at the jack. This means you get the effect of series wiring two speakers, as described above from Ted Weber's site, not only once, but twice.

Now, in the one that rgorke posted, there's only one pair of wires soldered to the input jack, which is why I refer to it as "series at the jack". You can think of it as two pairs of speakers each wired in parallell, then wired in series at the jack. I'm not sure if that would be accurate, but it helps to explain why it sounds different; now you have two pairs of speakers both wired in parallell, with the effects that has on the sound (again, refer to above).

[89custom]

Yes, they do sound subtly different, and I also get confused when I hear"parallel-series" or "series parallel"...the "at the jack" terminology is more descriptive.

Now if you only have a pair of speakers, then the difference between parallel and series between 2 speakers is much greater (besides the impedance change) .

Actually, I think all the above are the same...How I look at it, is two pairs are either each wired series (32ohms), then parallel to each other to get 16ohms, or each pair is wired parallel to each other (8 ohms) then connected together in series to get 16 ohms. All the above are the series pairs (32ohms) wired parallel.

I think.

[bruce]

I've noticed the newer Marshall cabs that are half open-back and house the silver alnicos are wired in parallel-series. Maybe this conserves the amount of wire used compared to the old 60 and 70's way.