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mcnach

1x cab at 4ohm *vs* 2x cabs at 8ohm - worth it?

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I have a 210 cab, 4ohm.
I'm considering adding a second identical cab. With my current amplifier it means connecting them in series for 8ohm.
Do I expect to get much of a volume increase? [1]

I did try a while ago 2x 112 cabs (4ohm total) vs 4x 112 cabs (8ohm) using a similar arrangement. It did sound bigger despite being 8ohm. But I suppose the effect will depend on the efficiency of the particular speakers etc.

I'd be interested to hear what experiences other people had.



[1] The long term plan is finding a suitable 2ohm capable head. There are many, I just haven't found 'the one'.

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Less power (assuming your amp makes less power into 8 ohms) into more speakers... I expect it will sound better, but not much louder, if at all..

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have a read of the impedance thread in the amps and cabs section I think you've either posted wrong or misunderstood

if you have one cab at 4 Ohms and add a second cab at 4 Ohms the Load will be 2 Ohms not 8 Ohms


this will cause damage to your amp due to it pushing out too much power with too little resistance which can lead to overheating issues (assuming that your amp wont run down to a 2 Ohm load if its the Markbass in your signature then I know it won't as I own one)


what you need is either one 4 Ohm cabinet or 2 8Ohm cabinets to create a total load of 4Ohms which is the minimum resistance its designed to work at

in reality more speaker area means more air moving but also less power going to each speaker I've used extra cabs in the past (1x15 under my 2x10) but its more for tonal reasons than actual extra power

again apologies if I've misinterpreted your post and the confusion is just a typo

Edited by Chrismanbass

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I think he gets that, Chrismanbass, he will need a special cable to wire 2 cabs in series.

2 cabs will sound louder than one because they are moving twice as much air. It doesn't matter whether the load is 4 ohm or 8 ohm.

Edited by pete.young

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Yep, contact our very own OBBM for a special splitter box that can enable connecting two 4ohm cabs to a 4ohm amp. As per Petes post, the sound will be fuller due to more speakers - this then gives the impression of being being louder. It certainly did when I connected both of my old Barefaced Super 12s up together, it was like a wall of bass in comparison to just having one going (which was big enough on its own soundwise).

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[quote name='Chrismanbass' timestamp='1492424376' post='3280071']
how so?

two cabs in series implies from head into one cab then another cable out of that into the other cab

connecting in parallel would need a y split cable i.e from head signal split into both cabs at the same time
[/quote]

It's not the cabs that count, it's the electrical connection between the speakers. Most amps, and many cabs, have two outputs, wired in parallel. Connecting a 4 ohm cab to each of these would, indeed, give a 2 ohm load to the amp, whether using the amp connectors or the cab connectors (ie: daisy-chained...). However, with the use of a specially-cabled series box connected to the amp, the cabs (and thus their speakers...) can be made to be electrically in series, showing a 8 ohm load to the amp. It's not that common, but has no danger to the amp. The solution will work just fine, and the overall sound will be fuller, and so seem slightly louder.

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Doubling the number of speakers gives you (all things being equal) +3dB , halving the power gives you -3dB.. So the nett effect is 0 dB..

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[quote name='Dad3353' timestamp='1492424861' post='3280077']
It's not the cabs that count, it's the electrical connection between the speakers. Most amps, and many cabs, have two outputs, wired in parallel. Connecting a 4 ohm cab to each of these would, indeed, give a 2 ohm load to the amp, whether using the amp connectors or the cab connectors (ie: daisy-chained...). However, with the use of a specially-cabled series box connected to the amp, the cabs (and thus their speakers...) can be made to be electrically in series, showing a 8 ohm load to the amp. It's not that common, but has no danger to the amp. The solution will work just fine, and the overall sound will be fuller, and so seem slightly louder.
[/quote]

Indeed upon doing some research on the subject I realised that the speaker connectors are wired so that they're parallel and thus deleted my incorrect comment

this is what lead to the earlier confusion about amp loading in my first post

thanks for bearing with me everyone :D

Chris

Edited by Chrismanbass

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[quote name='markstuk' timestamp='1492425237' post='3280088']
Doubling the number of speakers gives you (all things being equal) +3dB , halving the power gives you -3dB.. So the nett effect is 0 dB..
[/quote]
8 ohm is usually @ 2/3 of the watts of 4 ohm (e.g. 500w at 4 ohm would be about 350w at 8 ohm).
The other benefit of an 8 ohm load is less wear on the amp's components. This is coming from me, who runs a single 4 ohm cab. :lol:

The other thing to take into account, the amp probably won't be turned up full tilt, so the 2 cabs would give a fuller sound.

Edited by xgsjx

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[quote name='xgsjx' timestamp='1492426487' post='3280108']
8 ohm is usually @ 2/3 of the watts of 4 ohm (e.g. 500w at 4 ohm would be about 350w at 8 ohm).
The other benefit of an 8 ohm load is less wear on the amp's components. This is coming from me, who runs a single 4 ohm cab. :lol:

The other thing to take into account, the amp probably won't be turned up full tilt, so the 2 cabs would give a fuller sound.
[/quote]

+1dB then :D It will sound nicer..

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[quote name='markstuk' timestamp='1492422670' post='3280054']
Less power (assuming your amp makes less power into 8 ohms) into more speakers... I expect it will sound better, but not much louder, if at all..
[/quote]

That's a good description of my *very limited* experience. It sounded better, bigger... (do I hear 'heftier'? ;)) but I can't tell you if it was louder. Actually, the more I think about it, the more I think it's worth it. It would not be worth it if I needed a LOT more volume, but it might just be 'right' to fill in the sound better,, from what I remember on the 2 vs 4 112 cabs test...

hmmm.

Of course, once a 2ohm amp is available, it's clearly worth it. But it may not happen this summer.

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[quote name='Chrismanbass' timestamp='1492423336' post='3280057']
have a read of the impedance thread in the amps and cabs section I think you've either posted wrong or misunderstood

if you have one cab at 4 Ohms and add a second cab at 4 Ohms the Load will be 2 Ohms not 8 Ohms


this will cause damage to your amp due to it pushing out too much power with too little resistance which can lead to overheating issues (assuming that your amp wont run down to a 2 Ohm load if its the Markbass in your signature then I know it won't as I own one)


what you need is either one 4 Ohm cabinet or 2 8Ohm cabinets to create a total load of 4Ohms which is the minimum resistance its designed to work at

in reality more speaker area means more air moving but also less power going to each speaker I've used extra cabs in the past (1x15 under my 2x10) but its more for tonal reasons than actual extra power

again apologies if I've misinterpreted your post and the confusion is just a typo
[/quote]

No typo but maybe I did not explain the situation clearly.

I'm talking about the difference between using a single 210 4ohm cab into the LMIII amplifier, or two of the same 4ohm cabs into the same amplifier... but I'd wire them in series. That would result in 8ohm. So... more speakers, but lower power.

I had a test a while ago with two pairs of 112 cabs. Each cab is 8ohm, so each pair in parallel was 4ohm. That's equivalent to the situation I have now. I placed each pair in series.
4 speakers, despite being 8ohm, sounded bigger (better?) than 2 speakers. I just don't recall what my impression about total volume difference was. I think that the perceived 'heft' increase (I have to say that word :P) was very nice... but I must have thought that the extra cabs were a hassle (I can carry two boxes, amp and bass in one go... four boxes, no way, I'm not that talented ;)

My plan is for getting a 2ohm amp in the end as well, at which point then everything falls into place, but until then I was wondering if the series-wired two cabs would be worth using.

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[quote name='Lozz196' timestamp='1492424797' post='3280075']
Yep, contact our very own OBBM for a special splitter box that can enable connecting two 4ohm cabs to a 4ohm amp. As per Petes post, the sound will be fuller due to more speakers - this then gives the impression of being being louder. It certainly did when I connected both of my old Barefaced Super 12s up together, it was like a wall of bass in comparison to just having one going (which was big enough on its own soundwise).
[/quote]

Thanks. Yeah, that's a bit what my vague memory was telling me... but it's reassuring to hear other people's experiences to know I was not imagining it.
The connector box I used for parallel/series was indeed made by OBBM :)

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[quote name='markstuk' timestamp='1492427762' post='3280116']
+1dB then :D It will sound nicer..
[/quote]

Nicer enough to make me happy to carry the extra cab? :lol:

If only they made a version of the LMIII that were 2ohm capable!
I'm thinking of getting possibly a Mesa D800 for my birthday ;) which would do the job. But when I had my own test comparing the LMIII, Streamliner 900 and Mesa D800... I really really liked my LMIII best.

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[quote name='mcnach' timestamp='1492430008' post='3280137']
Nicer enough to make me happy to carry the extra cab? :lol:

If only they made a version of the LMIII that were 2ohm capable!
I'm thinking of getting possibly a Mesa D800 for my birthday ;) which would do the job. But when I had my own test comparing the LMIII, Streamliner 900 and Mesa D800... I really really liked my LMIII best.
[/quote]

Probably not :) Why not slave another amp off of your MB head?

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[quote name='markstuk' timestamp='1492430135' post='3280139']
Probably not :) Why not slave another amp off of your MB head?
[/quote]
+1 to that idea. Get a 2nd LMIII & go stereo. B)

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[quote name='markstuk' timestamp='1492430135' post='3280139']
Probably not :) Why not slave another amp off of your MB head?
[/quote]

Doh! That's a fantastic idea!
In fact... my original plan when I bought this cab was "and in the future I get a second LMIII", as they're so small and light that carrying two is not an issue. It doesn't have to be an LMIII if I'm just using the power section, of course, but they're not very expensive and so it serves as backup.
How did I forget??? :lol:

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[quote name='xgsjx' timestamp='1492430307' post='3280141']
+1 to that idea. Get a 2nd LMIII & go stereo. B)
[/quote]

yup, that's the winner...
I've even found a little doc in my computer where I was making all these notes and that was my plan last year :lol:

So that's settled. I'm getting a second cab within the next few weeks, and the amp will come next. Meanwhile I will get a chance to directly compare what I described in the OP and see how it feels.

Thank you for indulging me! :)

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If you are thinking about another 4 ohm 210 I'd also get a second amp, (you're using an LM3 I believe) and daisy chain both amps using the send/return. You can run each as a linked 4 ohm systems.

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[quote name='chris_b' timestamp='1492434720' post='3280183']
If you are thinking about another 4 ohm 210 I'd also get a second amp, (you're using an LM3 I believe) and daisy chain both amps using the send/return. You can run each as a linked 4 ohm systems.
[/quote]

Yes, this seems like the way to go :)

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You'll get an extra 3db for using two cabs. And an extra 6db in the bass frequencies where they couple.

Assuming you're no where near the limit of your current amp, there will be no benefit of running them in parallel vs running them in series.

i.e. If you're not getting amp distortion when running in series, running in parallel won't at any more power.

Edited by TimR

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[quote name='chris_b' timestamp='1492434720' post='3280183']
If you are thinking about another 4 ohm 210 I'd also get a second amp, (you're using an LM3 I believe) and daisy chain both amps using the send/return. You can run each as a linked 4 ohm systems.
[/quote]

There's a member here that plays some serious gigs using that setup, it's basically a 4x12 stack but with the top two as the Markbass combos and the bottom two as the matching ext speakers, he can cover anything from a little pub with a single combo right upto a symphony hall using all four,and he has done!

Edited by stingrayPete1977

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[quote name='TimR' timestamp='1492442787' post='3280268']
You'll get an extra 3db for using two cabs. [b]And an extra 6db in the bass frequencies where they couple.[/b]

Assuming you're no where near the limit of your current amp, there will be no benefit of running them in parallel vs running them in series.

i.e. If you're not getting amp distortion when running in series, running in parallel won't at any more power.
[/quote]

I had no idea that the bottom end response was supposed to get stronger. It would probably go some way to explain the difference I found between the 2x 112 cabs (4ohm) and twice that (4x 112 cabs, total 8ohm). The amplifier may not have been able to produce as much power when hooked up to the 8ohm load, but it sounded 'bigger'. I can't go into whether it was much louder or not as I did not measure it in anyway but it did feel... bigger. If the low end were improved, it could have easily accounted for some of that, especially as the cabs in question (TKS S112) are not very bassy at all, so the effect would be more noticeable. Interesting.

The single 210 with the LMIII is not enough, alone, for some gigs I have to play at. I can get away with it, but we will not sound great. I do need a bit more. Adding a second cab + second amp will surely do the trick, but I'm curious now to see what it will sound like with just one amp and the two cabs hooked up in series (8ohm), as a 2ohm load is not suitable for my chosen amp.

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[quote name='mcnach' timestamp='1492431546' post='3280154']


Doh! That's a fantastic idea!
In fact... my original plan when I bought this cab was "and in the future I get a second LMIII", as they're so small and light that carrying two is not an issue. It doesn't have to be an LMIII if I'm just using the power section, of course, but they're not very expensive and so it serves as backup.
How did I forget??? :lol:
[/quote]

The best idea, imho. As you say, you're only using the power amp section, so anything will suffice within reason. I use a Bugera head, which I picked up cheaply used, as a slave amp when I need more juice.

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The fact you can get a series speaker cable has got my juices flowing! I had some 'plans' which would have meant running a two channel power amp. If I can do it with my current amp then it will save me a lot on the investment.

As for slaving the LMIII, it's worth checking how the loop is set. I think they are default in parallel, so may or may not need opening up and changing over for best results. If so, it's a jumper connection in there somewhere!

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