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One amp, two different cabs


fryer
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Hi, I have two 410 cabs. One is a Peavey, 450 w at 4 ohm, and the other is ( or soon will be ) an Epifani, 1,000 w at 4 ohm. At the moment I have a Peavey Firebass amp, with 2 parallel speaker outputs. It has a crossover, with separate outputs for high and low, but these can only be used to put one of the signals back into the power amp section. So I assume this won't do it - as there are only the parallel speaker outputs.

So do I fit some sort of external, in-line resistor in the line output to the 450 w speaker cab ?

Or do I need a new amp which will do this. If so, what feature do I need to do this ?

Thanking You in anticipation.

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[quote name='fryer' post='1125710' date='Feb 13 2011, 09:54 AM']Hi, I have two 410 cabs. One is a Peavey, 450 w at 4 ohm, and the other is ( or soon will be ) an Epifani, 1,000 w at 4 ohm. At the moment I have a Peavey Firebass amp, with 2 parallel speaker outputs. It has a crossover, with separate outputs for high and low, but these can only be used to put one of the signals back into the power amp section. So I assume this won't do it - as there are only the parallel speaker outputs.

So do I fit some sort of external, in-line resistor in the line output to the 450 w speaker cab ?[/quote]

[color="#808080"]Forget trying to find 450W resistors and putting signals 'back into the power amp section' and so forth, this is just a rather unclear user manual.

All you need to do is take a speaker lead from the Low Output socket, feed that into one cab and then daisy chain from that cab to the next one.
Doesn't matter which way round you put them - one way round will sound different to the other, just pick the sound you prefer.

On the front of the amp you have 'FREQ' and 'BALANCE' controls.
Stick the 'FREQ' control to about halfway as a starting off point (you can tweak that later if you don't like the sound).
Stick the 'BALANCE' control all the way round to the LF end.[/color]

[color="#FF0000"][b]EDIT: To anyone reading this in the future, what I have stated above is totally wrong. Move along, nothing to see here! :)[/b][/color]

Edited by icastle
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[quote name='icastle' post='1125868' date='Feb 13 2011, 12:35 PM']Forget trying to find 450W resistors and putting signals 'back into the power amp section' and so forth, this is just a rather unclear user manual.

All you need to do is take a speaker lead from the Low Output socket, feed that into one cab and then daisy chain from that cab to the next one.
Doesn't matter which way round you put them - one way round will sound different to the other, just pick the sound you prefer.

On the front of the amp you have 'FREQ' and 'BALANCE' controls.
Stick the 'FREQ' control to about halfway as a starting off point (you can tweak that later if you don't like the sound).
Stick the 'BALANCE' control all the way round to the LF end.[/quote]

Why would you want to send line-level to a speaker cabinet? It'll be very quiet.

As for the original post I would imagine that the single Epi 4x10 will more than loud enough on its own.

The problem has nothing to do with maximum power handling capability, it will be if the 2 cabs have different sensitivities i.e. dBs per watt. If it's all about image then stand the Epi on the top of the Peavey but don't connect it.

By using two unmatched cabs on the single amp there will be no way to balance the perceived sound level. If you are intent on using these two very different cabs then you need a head with two separately adjustable power amp stages, or a rack pre-amp and stereo power amp or just get a separate power amp to drive the second cabinet and hang it onto the Firebass.

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[quote name='obbm' post='1125987' date='Feb 13 2011, 02:34 PM']Why would you want to send line-level to a speaker cabinet? It'll be very quiet.[/quote]

It's not line level. :)

EDIT: 'Low Output' in this case is related to the inbuilt crossover, not signal levels.

Edited by icastle
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[quote name='icastle' post='1126022' date='Feb 13 2011, 03:10 PM']It's not line level. :)

EDIT: 'Low Output' in this case is related to the inbuilt crossover, not signal levels.[/quote]


Read the spec and look at the block diagram.

The High and Low Outputs from the crossover are 0dBV, which is line level.

The only speaker outputs are the two jacks on the back panel marked "Outputs Speaker Jack Parallelled".

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[quote name='obbm' post='1126041' date='Feb 13 2011, 03:34 PM']Read the spec and look at the block diagram.

The High and Low Outputs from the crossover are 0dBV, which is line level.

The only speaker outputs are the two jacks on the back panel marked "Outputs Speaker Jack Parallelled".[/quote]

Bl**dy Hell ! :lol:

I thought it was wierd having speaker outputs on the front - I looked at the pic of the rear panel and completely missed them - three times! :)

You sure you didn't just draw them on there? :)

Totally take back what I said earlier but will leave it there as a lesson in both RTFM properly and humility.

Edited by icastle
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[quote name='fryer' post='1125710' date='Feb 13 2011, 04:54 AM']Hi, I have two 410 cabs. One is a Peavey, 450 w at 4 ohm, and the other is ( or soon will be ) an Epifani, 1,000 w at 4 ohm.[/quote]The power rating of the speakers is moot. Driver displacement determines how much power they can make use of, not the thermal rating. Too bad not one major manufacturer will reveal the displacement limited power of their cabs, though in deference that's partly because most of them don't know themselves. :)
Should you need to separately adjust their volume you can only do so with an amp that has dual independent power amps.

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[quote name='EdwardHimself' post='1126028' date='Feb 13 2011, 03:19 PM']it should be fine to daisy chain them together. Pretty sure the firebass is built to handle 2 ohm minimum load.[/quote]

Yes it does take 2 ohms. Would it be 2 ohms if I daisy chained them, and if I used both speaker outlets ?

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[quote name='obbm' post='1125987' date='Feb 13 2011, 02:34 PM']Why would you want to send line-level to a speaker cabinet? It'll be very quiet.

As for the original post I would imagine that the single Epi 4x10 will more than loud enough on its own.

The problem has nothing to do with maximum power handling capability, it will be if the 2 cabs have different sensitivities i.e. dBs per watt. If it's all about image then stand the Epi on the top of the Peavey but don't connect it.

By using two unmatched cabs on the single amp there will be no way to balance the perceived sound level. If you are intent on using these two very different cabs then you need a head with two separately adjustable power amp stages, or a rack pre-amp and stereo power amp or just get a separate power amp to drive the second cabinet and hang it onto the Firebass.[/quote]

You say that ' The problem has nothing to do with maximum power handling capability '. But why not, 'cos if I put 700 watts out of the Firebass, surely the Epi would handle this, but the Peavey wouldn't ?? Sorry but I don't see why it isn't a problem.

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[quote name='icastle' post='1126048' date='Feb 13 2011, 03:46 PM']Bl**dy Hell ! :lol:

I thought it was wierd having speaker outputs on the front - I looked at the pic of the rear panel and completely missed them - three times! :)

You sure you didn't just draw them on there? :)

Totally take back what I said earlier but will leave it there as a lesson in both RTFM properly and humility.[/quote]

It's definately got a couple of holes in the back.

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[quote name='fryer' post='1126359' date='Feb 13 2011, 08:09 PM']You say that ' The problem has nothing to do with maximum power handling capability '. But why not, 'cos if I put 700 watts out of the Firebass, surely the Epi would handle this, but the Peavey wouldn't ?? Sorry but I don't see why it isn't a problem.[/quote]

700W between two cabs so 350W each. And that's irrelevant anyway as it'll be the unspecified excursion-limited power-handling restriction that kicks in first. Just 300W into an 8x10" stack will be so loud it'll drown out most drummers so it remains a moot point.

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[quote name='fryer' post='1126359' date='Feb 13 2011, 08:09 PM']You say that ' The problem has nothing to do with maximum power handling capability '. But why not, 'cos if I put 700 watts out of the Firebass, surely the Epi would handle this, but the Peavey wouldn't ?? Sorry but I don't see why it isn't a problem.[/quote]

What Alex said

plus

You are very unlikely, unless you are playing Wembley, to ever run the whole rig flat out and be able to stand in front of it.

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[quote name='alexclaber' post='1126375' date='Feb 13 2011, 08:17 PM']700W between two cabs so 350W each. And that's irrelevant anyway as it'll be the unspecified excursion-limited power-handling restriction that kicks in first. Just 300W into an 8x10" stack will be so loud it'll drown out most drummers so it remains a moot point.[/quote]

Alex, does this apply whichever way I connect them - either daisy chained or via 2 separate cables ?

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From your first statement it seemed you wanted to bi amp these cabs, or was confused about the crossover. As from everyone else you can just link these to this amp as it will handle the impedance, the Epi will be twice as loud as the peavey due to the in-efficient peavey speakers compared with the Epi. This fact alone will drive you mad. When you get the new cab you will not want to use the Peavey 4x10 again and will not need it so problem solved. The only way to solve the imbalance in volume would be to bi amp so you can turn down the Epi to match the Peavey output, but again can’t see you needing the complication of getting another amp to do this. check out the extra volume of the amp with the new cab before worrying about using two.
note. this extra volume you will gain is nothing to to do with the stated wattage of each cab but the speaker efficiency, a reason you should avoid mixing cabs like this

Edited by deepbass5
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[quote name='deepbass5' post='1126553' date='Feb 13 2011, 11:22 PM']the Epi will be twice as loud as the peavey due to the in-efficient peavey speakers compared with the Epi.[/quote]

The Epifani may be slightly more sensitive overall than the Peavey but it won't be a big difference - I wouldn't be surprised if the Peavey is a bit louder in the lows. Whatever your budget you can't beat Hoffman's.

Richard, it doesn't matter whether you daisychain or run two leads from the amp, electrically it's the same.

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Speaker attenuators tend to be aimed at guitarists where even a 50W amp is more than sufficient for your average venue.

I have a Marshall Power Break which is rated at 150W power dissipation for use with amps up to 100W RMS output. I haven't seen any speaker attenuators for use with amps over 200W RMS output which pretty much limits their use with most bass rigs.

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Just to clarify my last post, Sorry I was not trying to be disrespectful, Two similar 4x10 would be ok if you need that sort coverage and more useful than an 8x10. But modern cabs and speakers tend to be a lot more efficient than older designs. I do rate PV gear but the 10" scorpions are not as efficient as the PV black widow 12" and 15" speakers so without checking I recon the Epi will be pushing the 100dB level where the PV 4x10 will probably be in the low 90's.
My last rig was a PV 15 with Carvin 2x10 but I did bi amp these. I still think pound for pound the PV 15 is one of the best out there regardless of what fancy name or colour the speakers.

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[quote name='deepbass5' post='1127380' date='Feb 14 2011, 06:06 PM']Just to clarify my last post, Sorry I was not trying to be disrespectful, Two similar 4x10 would be ok if you need that sort coverage and more useful than an 8x10. But modern cabs and speakers tend to be a lot more efficient than older designs. I do rate PV gear but the 10" scorpions are not as efficient as the PV black widow 12" and 15" speakers so without checking I recon the Epi will be pushing the 100dB level where the PV 4x10 will probably be in the low 90's.
My last rig was a PV 15 with Carvin 2x10 but I did bi amp these. I still think pound for pound the PV 15 is one of the best out there regardless of what fancy name or colour the speakers.[/quote]

Hey, no disrespect taken. The Epi is 103 dB - don't know about te Peavey. It's just I like the sound of the Peavey. I've had an Epi UL 310 before, which in hindsight, I wish I'd kept. Anyway, will have the Epi 410 this week, courtesy of OH Murphy, so we'll see how it goes with that one.

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