My thoughts on Marshall cab

[SeraphimTN]

Re: My thoughts on Marshall cab

Wait, why can't I just wire each speaker to the output? Would that not be 8 ohms since it's oging directly to the speaker?

 

[ErikH]

Re: My thoughts on Marshall cab

Wait, why can't I just wire each speaker to the output? Would that not be 8 ohms since it's oging directly to the speaker?

Nope. How the speakers are wired to the output determines the final impedence. Just wiring the leads of all 4 to the jack is wiring them in parallel, which in your case will equal 2 ohms. The speakers are rated for a load, the amp sees that load and is wired to handle it or not.

 

[SeraphimTN]

Re: My thoughts on Marshall cab

Nope. How the speakers are wired to the output determines the final impedence. Just wiring the leads of all 4 to the jack is wiring them in parallel, which in your case will equal 2 ohms. The speakers are rated for a load, the amp sees that load and is wired to handle it or not.

This....is a pain in the butt. What about keeping two of the 8 ohm speakers and replaced 2 with a V30 or some other 16 ohm speaker?

 

[ErikH]

Re: My thoughts on Marshall cab

This....is a pain in the butt. What about keeping two of the 8 ohm speakers and replaced 2 with a V30 or some other 16 ohm speaker?

Still not a 16 ohm load. The only way you'll get a 16 ohm load: (actually, there's 2 but the first one is easier)

1. Get 4 16 ohm speakers and wire the cab series/parallel.
2. Get 4 4 ohm speakers and wire them in series.

Anything else will be a mis-match.

 

[SeraphimTN]

Re: My thoughts on Marshall cab

Still not a 16 ohm load. The only way you'll get a 16 ohm load: (actually, there's 2 but the first one is easier)

1. Get 4 16 ohm speakers and wire the cab series/parallel.
2. Get 4 4 ohm speakers and wire them in series.

Anything else will be a mis-match.

Ok this is stupid....the cab CAN and WAS rewired for 8....what's the harm in running an 8 and 16 load cab?? Both meet the head's requirements and I LIKE the Marshall more quiet if that's what it will do. What's wrong with 8 and 16??

 

[ErikH]

Re: My thoughts on Marshall cab

The cab was "not" rewired for 8. If it was, your meter wouldn't show "2". From what you described on how it is right now, all 4 speakers are wired in parallel to the jack, that equals 2 ohms.

Running 8 and 16 is a mismatch. You may like it, but it's not necessarily safe for the amp.

 

[SeraphimTN]

Re: My thoughts on Marshall cab

The cab was "not" rewired for 8. If it was, your meter wouldn't show "2". From what you described on how it is right now, all 4 speakers are wired in parallel to the jack, that equals 2 ohms.

Running 8 and 16 is a mismatch. You may like it, but it's not necessarily safe for the amp.

I meant, the cab was wired for 8 before I touched it:laugh2: From what many people tell me, it's safe for the head, but there will be a volume difference between the two, which is perfectly fine by me.

 

[ErikH]

Re: My thoughts on Marshall cab

I meant, the cab was wired for 8 before I touched it:laugh2: From what many people tell me, it's safe for the head, but there will be a volume difference between the two, which is perfectly fine by me.

Yeah, before you touched it it was 8 ohms. I highly recommend putting it back to that. Check it with the meter before using it though to make sure it reads 8 ohms.

Is your head solid state? If so, you *could* get away with it but IMO, the volume difference would be odd, and it's better to run 2 cabs of the same load rather than mis-matched cabs. You'd have to hear both cabs with the same load to determine whether you truly like it that way or not.

I can tell you this, you'll notice a difference in volume on that cab from 2 to 8 ohms right off the bat.

 

[SeraphimTN]

Re: My thoughts on Marshall cab

Yeah, before you touched it it was 8 ohms. I highly recommend putting it back to that. Check it with the meter before using it though to make sure it reads 8 ohms.

Is your head solid state? If so, you *could* get away with it but IMO, the volume difference would be odd, and it's better to run 2 cabs of the same load rather than mis-matched cabs. You'd have to hear both cabs with the same load to determine whether you truly like it that way or not.

I can tell you this, you'll notice a difference in volume on that cab from 2 to 8 ohms right off the bat.

Yeah, it'll be more even that in it was in volume lol. In the manual it said this about the 2 speaker jacks on the head.....The two jacks are a parallel ciruit, ensure the overall impedance for the connected speakers does not go below 4 ohms. Does this shed any light?

 

[ErikH]

Re: My thoughts on Marshall cab

Yeah, it'll be more even that in it was in volume lol. In the manual it said this about the 2 speaker jacks on the head.....The two jacks are a parallel ciruit, ensure the overall impedance for the connected speakers does not go below 4 ohms. Does this shed any light?

Yup. That means when running both sides of the cab (both jacks) at the same time, it's a 4 ohm load per jack, but when run in mono (one jack, usually the left one, and labelled as such) it is 8 ohms.

Look up US Speaker on Google. They have a page showing series/parallel, series, and parallel wiring with diagrams and explanation. That'll help answer a lot of questions.

 

[SeraphimTN]

Re: My thoughts on Marshall cab

Yup. That means when running both sides of the cab (both jacks) at the same time, it's a 4 ohm load per jack, but when run in mono (one jack, usually the left one, and labelled as such) it is 8 ohms.

Look up US Speaker on Google. They have a page showing series/parallel, series, and parallel wiring with diagrams and explanation. That'll help answer a lot of questions.

The manual is for the head outputs, not the cab. I googled that, thanks....helpful.

 

[ErikH]

Re: My thoughts on Marshall cab

The manual is for the head outputs, not the cab. I googled that, thanks....helpful.

Ah, yeah, I shoulda caught that...lol. You *should* be ok, but I'm from the school that no matter what it says, make sure the cabs match impedences. And you're welcome for the info. That page is a great one to bookmark for easy reference.

 

[Gr8Scott]

Re: My thoughts on Marshall cab

FWIW - EricH is 100% correct on everything in this thread. Voice of experience talking right there. Don't assume anything in electronics. Check and verify everything you possibly can when you modify or do something yourself. Doing otherwise is foolhardy. If your meter says 2 ohms, you're getting two ohms.

If you really want to use both cabs at the same time with the same head, please do yourself a favor and rewire the cabs to match impedance. If one 4x12 has 8 ohm speakers and the other has 16 ohm speakers, get some more 16 ohms speakers and re-wire the cab so it's wiring matches the other 16 ohm marshall cab. You can get some incredible speakers from ScottF for cheap. Mojotones G12H30/Vintage 30 mix in 16 ohms in the HK cab would be a killer mix. Probably cost you not so much either. Then your HK cab would be a real screamer and your cab impedances would match.

 

[SeraphimTN]

Re: My thoughts on Marshall cab

FWIW - EricH is 100% correct on everything in this thread. Voice of experience talking right there. Don't assume anything in electronics. Check and verify everything you possibly can when you modify or do something yourself. Doing otherwise is foolhardy. If your meter says 2 ohms, you're getting two ohms.

If you really want to use both cabs at the same time with the same head, please do yourself a favor and rewire the cabs to match impedance. If one 4x12 has 8 ohm speakers and the other has 16 ohm speakers, get some more 16 ohms speakers and re-wire the cab so it's wiring matches the other 16 ohm marshall cab. You can get some incredible speakers from ScottF for cheap. Mojotones G12H30/Vintage 30 mix in 16 ohms in the HK cab would be a killer mix. Probably cost you not so much either. Then your HK cab would be a real screamer and your cab impedances would match.

But that's not what I want...I want what I have. I just rewired the hughes for 8 ohms and there is hardly any volume difference between the two cabs. The speakers in the Hughes MAKE the hughes what it is. As long as the total ohms from both cabs into the head is greater than 4 ohms...it poses no problem whatsoever. The head isn't all tube remember.

 

[pinto79]

Re: My thoughts on Marshall cab

But that's not what I want...I want what I have. I just rewired the hughes for 8 ohms and there is hardly any volume difference between the two cabs. The speakers in the Hughes MAKE the hughes what it is. As long as the total ohms from both cabs into the head is greater than 4 ohms...it poses no problem whatsoever. The head isn't all tube remember.

If you like the H&K, then consider changing the Marshall cab to 8 Ohm speakers to make an 8 ohm cab, then the two together would make a 4 ohm load.

Your amp may be able to deal with that, check first.

 

[hareek]

Re: My thoughts on Marshall cab

I have a marshall tsl 100 with a 1960A cab. I was under the impression that you only use the 16 ohm out jack on the head if your running it into only 1 cabinet with a 16 ohm input. Otherwise if your running two cabs, you use the two 4/8 ohm jacks. So in your case, why is the 16 ohm out/in setup even an option? I'm not really an expert with head-to-cab wiring at all. My marshall is really my only experience in this area, but this is how I understood it. Someone please correct me if I'm wrong or elaborate on what I know as I could use some clarification.

Edit: going back and reading through this thread again, I think I misunderstood everything. I understood at as you guys talking about the wiring scheme from head to cab, but going back through, it looks like you are talking about the specific wiring scheme for the speakers to the input jack just for the cab itself. my mistake. everyone please continue.

 

[Gr8Scott]

Re: My thoughts on Marshall cab

You can't wire the marshall to 8 ohms without using different speakers. It can be 16 or 4, but not 8 so far as I know unless you only use two speakers and leave the other two non-functional. That of course is an option, though I don't see much usefulness in doing that.

Is it alright to use a non-tube amp with odd speaker ohm ratings like that? One would think it would be a tonal nightmare, but one could also be wrong. Could be that impedance doesn't affect the tone of non-tube stuff quite as much. Dunno as I don't know much about non-tube amps. Either way, do what makes ya feel good.

 

[SeraphimTN]

Re: My thoughts on Marshall cab

You can't wire the marshall to 8 ohms without using different speakers. It can be 16 or 4, but not 8 so far as I know unless you only use two speakers and leave the other two non-functional. That of course is an option, though I don't see much usefulness in doing that.

Is it alright to use a non-tube amp with odd speaker ohm ratings like that? One would think it would be a tonal nightmare, but one could also be wrong. Could be that impedance doesn't affect the tone of non-tube stuff quite as much. Dunno as I don't know much about non-tube amps. Either way, do what makes ya feel good.

I acually, after playing both a lot today, don't hear any real volume difference nor any problem with the tone. Sounds GREAT!

 

[Mephis]

Re: My thoughts on Marshall cab

Your attax is really a solid state amp, I wouldn't worry about it much TBH, if you notice some strange sounds or anything odd make sure to shut it down.

On a tube amp, yea that would be a massive problem, but on that I don't see it having as much of a chance to damage much.

Still I wouldn't promote you to run both cabs at the same time.

 

[Kommerzbassist]

Re: My thoughts on Marshall cab

Ok just FYI I created a little graphic (in paint cause I am lazy)

As you can see, if two speakers are connected +@- it's in series, if they are connected +@+ and -@-, it's parallel. Actually it's easy to understand:
If the current has to run through a series of loads, it's wired in series, if it can run trough them 'at the same time' or parallel, it's parallel.


So now how do you get the load:
First, we say Speaker one is R1=8Ohm and speaker two is R2=8Ohm aswell. R is the complete resistance the head will see in your case.

It's easy to explain resistance if you think of the circuit as a highway.

Series is easy.
You have two highway parts, both with 3 tracks, which come one after the other, so you'll have the same traffic resistance on both parts, since they have the same number of tracks, but still, since you have to pass both, the resistance sums up altogether.
Or
Since the current has to run through both loads to get from + to - or actually vice versa, the loads just add up, so it's R=R1+R2.

Ok now parallel. Imagine you have two highway parts again, both 3 tracks but they run in parallel, meaning the traffic splits up on the two parts which means LOWER resistance for you if you want to drive though (as you'll have more space altogether)
This formula is a bit more tricky: 1/R = 1/R1 + 1/R2 => R=1/(1/R1+1/R2)
Now you can also transform it and get
R=(R1*R2)/(R1+R2)

or in your case, for 4x8Ohm: R = 1/(1/8+1/8+1/8+1/8)=2

Hope that helps.