wiring two cabs

[Al Heeley]

Peavey Tour 450 head & 2 hartke cabs: Does it make any difference if I wire each cab from the two separate outputs on the amp, or daisy chain them from amp to cab1, then cab1 to cab 2?
Is there a best method?

[bigjohn]

That depends on the head and the cabs.

What your amp is rated down to and what impedance the cabs are.

Most likely your cabs are 4ohm and your amp is only rated down to 4ohm, so you'll have to daisy chain them up to 8ohm.

Unless your amp will do 2ohm, or your cabs are 8ohm then you'll able to use each output.


Daisy chaining - you add up the impedance on the cabs.

Series is a bit more complicated but if you've got matching cabs you divide the impedance by the number of cabs. So you'll have an impedance of 2ohm.

The cabs have got to be more or equal to the rating on the amp or you'll draw too much power from the amp and overheat / kill it.

I'm sure there's a sticky somewhere if you have a look for it.

Edited July 7, 2010 by bigjohn

[geoffbyrne]

Be careful here!!! Very few cabs, to my knowledge, have standardised series wiring.

If you take a cable from cab to cab you will, most likely, still be connecting in parallel.

I remember once, a long time ago, seeing a Vox cab with 2 black plastic-nutted jacks marked "parallel" and one white-nutted socket marked "series", but apart from doing custom wiring, that's all.

Geoff.

[Colledge]

[quote name='bigjohn' post='888661' date='Jul 7 2010, 05:03 PM']Series is a bit more complicated but if you've got matching cabs you divide the impedance by the number of cabs. So you'll have an impedance of 2ohm.[/quote]
i think you mean parallel

[quote name='geoffbyrne' post='888692' date='Jul 7 2010, 05:28 PM']Be careful here!!! Very few cabs, to my knowledge, have standardised series wiring.

If you take a cable from cab to cab you will, most likely, still be connecting in parallel.

I remember once, a long time ago, seeing a Vox cab with 2 black plastic-nutted jacks marked "parallel" and one white-nutted socket marked "series", but apart from doing custom wiring, that's all.

Geoff.[/quote]

+1

[Beedster]

[quote name='geoffbyrne' post='888692' date='Jul 7 2010, 05:28 PM']If you take a cable from cab to cab you will, most likely, still be connecting in parallel.[/quote]

That's my understanding, certainly with the gear I'm currently using, the manual for which suggests there's no difference running each cab from a separate output or from cab 1 to cab 2? Due to a rather bizarre short cable situation, I've recently had to do the latter and I've certainly not noticed the drop in power you'd expect from a 4ohm load becoming a 16 ohm load?

[bigjohn]

[quote name='Colledge' post='888705' date='Jul 7 2010, 05:40 PM']i think you mean parallel[/quote]

Yes I do. Soz.

[quote name='Beedster' post='888714' date='Jul 7 2010, 05:45 PM']That's my understanding, certainly with the gear I'm currently using, the manual for which suggests there's no difference running each cab from a separate output or from cab 1 to cab 2? Due to a rather bizarre short cable situation, I've recently had to do the latter and I've certainly not noticed the drop in power you'd expect from a 4ohm load becoming a 16 ohm load?[/quote]


I rewired my Low b2s so they were 16ohm cabs rather than 4 ohm and didn't notice a drop in power.

Similarly there's a 2x12 at our studio that was a 4ohm cab but has been rewired as 2 8 ohm independent speakers in the same cab. That's just as loud with my poweramp at either 2x500W@4ohm as it is 2x250W@8ohm.

Wired that way though it's much louder (and better) than it was as a 4ohm cab and only using one side of my poweramp - 500W@4ohm. (which "[i]should[/i]" be just the same as 2x250W@8ohm)

I certainly don't believe you need to match the lowest impedance to get "power" out of your amps. Most of the extra power you're using is turning into heat rather than generating audible increases in volume. That and whatever law it is... the one which says you need 10x the power to notice an increase in volume. It's logarithmic innit. So if you compare 16ohm to 4 ohm, you're still only 4x more "powerful", which isn't enough to notice. The heat thing has great bearing though I reckon.

You've just got to be careful not to overload your amps. Underloading is fine.

Edited July 7, 2010 by bigjohn

[Bill Fitzmaurice]

[quote name='Al Heeley' post='888648' date='Jul 7 2010, 11:54 AM']Peavey Tour 450 head & 2 hartke cabs: Does it make any difference if I wire each cab from the two separate outputs on the amp, or daisy chain them from amp to cab1, then cab1 to cab 2?
Is there a best method?[/quote]Electrically both methods are identical, a parallel load. The only potential advantage to running the cables each separately to the amp is then the current flow and cable resistance loss is divided between them. That's only an advantage if the cables are shy on current capability and have high DCR from being under gauged.

[bigjohn]

[quote name='Bill Fitzmaurice' post='888814' date='Jul 7 2010, 06:47 PM']Electrically both methods are identical, a parallel load. The only potential advantage to running the cables each separately to the amp is then the current flow and cable resistance loss is divided between them. That's only an advantage if the cables are shy on current capability and have high DCR from being under gauged.[/quote]


Indeed.

If you we're going to run them parallel I'd have them rewired to give them greater impedance. You won't notice that you're not drawing "the full power" from the amp.

Or have them rewired so you can run them in series.

Edited July 7, 2010 by bigjohn

[Bill Fitzmaurice]

[quote name='bigjohn' post='888848' date='Jul 7 2010, 02:36 PM']Indeed.

If you we're going to run them parallel I'd have them rewired to give them greater impedance. You won't notice that you're not drawing "the full power" from the amp.

Or have them rewired so you can run them in series.[/quote]
The jacks on the back of the amp are parallel wired, as are the paired jacks on the cabs. It doesn't matter whether you use both jacks on the amp or run one cable to one cab and daisy chain the second cab from the first, it's still parallel wiring. You only get series wiring when you use a specially made series wiring harness.

[Al Heeley]

Ypu are perfectly correct Bill, both designed to run parallel, I was curious to find if there was any difference atall. Somehow I feel happier using the amp heads twin outputs but now i am intrigued about the possibility to series-wire, and what I could gain from this. Both cabs are 8ohm - 4x10 hartke XL and hartke 115XL.
The Tour 450 head is designed to run at 450w into 4ohm. I think its about 300w into 8ohm.
The hartke booklet suggests daisy chaining - i guess if your amp head has only one output socket then you have no choice.

[warwickhunt]

[quote name='Bill Fitzmaurice' post='888814' date='Jul 7 2010, 06:47 PM']Electrically both methods are identical, a parallel load. The only potential advantage to running the cables each separately to the amp is then the current flow and cable resistance loss is divided between them. That's only an advantage if the cables are shy on current capability and have high DCR from being under gauged.[/quote]

To add to Bill's reasoning for preferably running two leads from the parallel outs as opposed to daisy chaining is that if you are daisy chaining cabs live and the lead from head to cab #1 fails then you have zero output going to both of your cabs; however, if 1 lead fails and you are running parallel outs from your head then at least 1 of your cabs will still be running. Ever the pessimist I always like to cover the options for that dreaded 'silent moment' whilst performing!

[Merton]

[quote name='Al Heeley' post='888918' date='Jul 7 2010, 08:48 PM'](snip...) now i am intrigued about the possibility to series-wire, and what I could gain from this. Both cabs are 8ohm - 4x10 hartke XL and hartke 115XL.
The Tour 450 head is designed to run at 450w into 4ohm. I think its about 300w into 8ohm.[/quote]
Don't bother with series wiring, it'll just increase the load on the amp which will lower the power output to the cabs. Plus it's a pain in the arse to do it when your set up sounds perfect as it is

[bigjohn]

[quote name='Bill Fitzmaurice' post='888901' date='Jul 7 2010, 08:32 PM']The jacks on the back of the amp are parallel wired, as are the paired jacks on the cabs. It doesn't matter whether you use both jacks on the amp or run one cable to one cab and daisy chain the second cab from the first, it's still parallel wiring. You only get series wiring when you use a specially made series wiring harness.[/quote]


Are they... If they are, that's why I suggested them being rewired (the speakers in the cabs).

ie - rewire each 4ohm cab (2x8ohm speakers) as 16ohm. You could then use each each output on the amp.

Or wire them with the correct inputs/outputs so you can daisychain them.

it's not rocket science is it?

Edited July 7, 2010 by bigjohn

[Merton]

[quote name='bigjohn' post='889019' date='Jul 7 2010, 10:05 PM']Are they... If they are, that's why I suggested them being rewired (the speakers in the cabs).

ie - rewire each 4ohm cab (2x8ohm speakers) as 16ohm. You could then use each each output on the amp.

Or wire them with the correct inputs/outputs so you can daisychain them.

it's not rocket science is it?[/quote]
But Al's cabs are 8 ohm so this argument is all a bit of a waste on this thread! I do see where you're coming form if someone were in the quandry though

[bigjohn]

[quote name='Merton' post='889041' date='Jul 7 2010, 10:23 PM']But Al's cabs are 8 ohm so this argument is all a bit of a waste on this thread! I do see where you're coming form if someone were in the quandry though [/quote]

Here for posterity!

[geoffbyrne]

[quote name='Al Heeley' post='888648' date='Jul 7 2010, 04:54 PM']Peavey Tour 450 head & 2 hartke cabs: Does it make any difference if I wire each cab from the two separate outputs on the amp, or daisy chain them from amp to cab1, then cab1 to cab 2?
Is there a best method?[/quote]


No, it doesn't matter. Assuming your cabs are 8 Ohms, both ways will result in a load of 4 Ohms. Most peavey amps seem to be OK down to 2 Ohms (most Peavey cabs are 4 Ohms).

G.

[Al Heeley]

ooh-errr, Peavey say 4ohms should be minimum load for their Tour series heads.
I asked in the Hartke subforum about how to rewire the 410 cab as a 4ohm to get the max push out of the amp and was told it could not be done.

[obbm]

[quote name='Al Heeley' post='889401' date='Jul 8 2010, 12:01 PM']ooh-errr, Peavey say 4ohms should be minimum load for their Tour series heads.
I asked in the Hartke subforum about how to rewire the 410 cab as a 4ohm to get the max push out of the amp and was told it could not be done.[/quote]

Laws of Physics I'm afraid. 8-ohm cab which has 4 x 8-ohm speaker can only be rewired to 32-ohms or 2-ohms.

[warwickhunt]

[quote name='Al Heeley' post='889401' date='Jul 8 2010, 12:01 PM']I asked in the Hartke subforum about how to rewire the 410 cab as a 4ohm to get the max push out of the amp and was told it could not be done.[/quote]

I'm confused (doesn't take much)!

Are you talking about wanting to rewire your Hartke 4x10 to 4 ohms from the 8 ohm it presently is? As OBBM has said it can't be done but more importantly 'why' would you want to (unless you were downsizing)? Utilising your pair of 8ohm cabs with your present amp, you are getting the max out of your amp; even if you changed the drivers in your 4x10 so that you could achieve a 4 ohm load you would then be unable to run your new 4 ohm 4x10 in conjunction with any other cab (your 1x15 thus rendered redundant). Worst of all you'd be getting less spread out of the single 4 ohm 4x10 than you would out of the pairing of 8 ohm 4x10 + 1x15 AND at least your 'stack' will be closer to ear level so that you perceive more volume.

[geoffbyrne]

[quote name='Al Heeley' post='889401' date='Jul 8 2010, 12:01 PM']ooh-errr, Peavey say 4ohms should be minimum load for their Tour series heads.
I asked in the Hartke subforum about how to rewire the 410 cab as a 4ohm to get the max push out of the amp and was told it could not be done.[/quote]


fair enough, if the manual says that 4 Ohms is the optimum, then you already have the ideal setup in 2x8Ohm cabs. A lot of Peavey amps will go to 2 Ohms, however.

G.

[Bill Fitzmaurice]

[quote name='Al Heeley' post='889401' date='Jul 8 2010, 07:01 AM']I asked in the Hartke subforum about how to rewire the 410 cab as a 4ohm to get the max push out of the amp and was told it could not be done.[/quote]Nor is it generally worthwhile anyway. Few cabs will take more than half their thermal power rating before exceeding excursion limits. Even were that not an issue you'd only get 2dB additional output from a 4 ohm versus 8 ohm cab. That's audible, but just.

[Alfie]

Slight hijack

Running an Orange Terror Bass into two 8 ohm cabs, should the switch on the back of the amp be set to 4 ohm or 8 ohm?

[obbm]

[quote name='Alfie' post='889940' date='Jul 8 2010, 10:31 PM']Slight hijack

Running an Orange Terror Bass into two 8 ohm cabs, should the switch on the back of the amp be set to 4 ohm or 8 ohm?[/quote]

2 X 8-ohm Cabs = 4-ohms

[Alfie]

[quote name='obbm' post='889945' date='Jul 8 2010, 10:34 PM']2 X 8-ohm Cabs = 4-ohms[/quote]

Thank you