Hi,

I've got a pair of McGregor R15/2H/200 subs and a pair of Peavey Pro-12's alongside a Studiomaster 1200D amp (which has 2 channels). I'm looking at connecting a Pro-12 into each channel on the amp and then a McGregor into each Pro-12's output. However, this will probably mean that the high, mid and low signal will be sent to both the Pro-12s and McGregors when ideally the high and mid will be sent to the Pro-12s whilst the low should go to the McGregors.

So a couple of questions. Firstly, does anyone know whether the Pro-12s are capable of sending out just the sub frequencies to the McGregors? I've tried looking on the Peavey site for the manual but it doesn't seem to load.

Secondly, the Studiomaster amp can push out 375w at 8ohm, 600w at 4ohm and 750w at 2ohm (according to this site). The pro-12s and McGregors are 4ohm each so how many ohms (per channel) will the amp see?

Many thanks for reading all that!

Rich

You are trying to connect the speakers the wrong way round.

According to the Manufactures website Here (bottom of the page) the subwoofer has a passive crossover.

So you need to connect the speakers like this.

On the back of the subwoofer there should be 2 Speakon connectors. One of these will be marked input. Plug the output of the amp into the input of the subwoofer. Connect the high out of the subwoofer to the Pro-12's.

Josh

.

The peavey crossover will only separate the signal as needed within itself ie to horn and cone drivers. The output will be a parallel run on to another.

Do the McGregors may have an internal crossover this one will send bass to the McG cone driver and allow the mid and top on to something else (in your case the peaveys.)

Impedance!
A 4 ohm peavey and a 4 ohm McG will parallel to give a 2 ohm load and even though this is supposedly OK it may not be OK in reality.

If the McGregors have a crossover inside and a Hi-pass out, drive the McG and take the peavey from the hi-pass and the load on the amp should be 4 ohms.

The model you've linked to is not the same as mine as the speakers I have do not have speakon connectors - they have 2 jack sockets which are not marked with either input or output.



I'm not sure whether the McG's have an internal crossover or not as I can't find any documentation for them anywhere. However, I have been in touch with MTR support (an McG supplier) regarding the speakers impedance so perhaps they'll be able to shed some light on the matter.



Could you explain this further please? Why does this connection method cause 4ohm instead 2 ohm?


Thanks both for the replies.

As for the bass cabs having no markings, and two jack plug inputs this would suggest that they are linked in parallel and no internal crossover.
As regards the Impedance,

This is a very common misconception.
I too thought this until very recently, apparently it depends on the crossover.

Rob Beech, and plenty of others can explain this better.
(your making a name for yourself Rob!)

I think what you need is an active crossover, ir a cheaper way is to install your own passives into your bass cabs if you are handy at a bit of DIY.

John Denim.

Optimum solution is to have an active crossover and an amp for each set of speakers. That allows great control but at a cost.

I fear the dual amp way is probably the only option. Peavey bass bins do have a 2-way load-sharing crossover for their tops meaning even one 4ohm bin plus 1 4ohm top cab, correctly wired, will only show as 4 ohms. They design it that way so they can sell two tops, two bins and a single amp as a package. They include the special jumper cable, wired speakon-pair-2 (bass end) to speakon-pair-1 (high end).

I'm not massively familiar with McGregor bins (I do use the tops in the workshop) but as mentioned it does seem like they have just a low-pass crossover in them, jacks wired parallel. If this is the case your poor Studiomaster will see a 2ohm load and they dont like that; they'll trip on overheat after a few minutes. I had a customer do exactly that, mixing and matching 4-ohm Peavey tops with 4-ohm skytronic bins and wondering why the Stud overheated half way through his first number.

so to cap, unscrew the back of the mcgregors and see if theres a crossover in there. Judging by how there are 2 jacks, id presume not. However there may still be a crossover in there, just for the input, meaning you can put a full range signal straight into it.

With this level of audio, not high wattages and not high quality, id be reluctant to lump around a 2nd amp. Perhaps you could spend £10 and get some passive crossovers into the back of the mcgregors? Skytronic do some 400w ones ive seen, although id check the ohmages again

Maybe a quick phone call to mcgregor to check the specs of your sub re- crossover etc.

If there is not a crossover in there im sure they can recomend a suitable crossover to go in them or maybe sell you one .

They are a great bunch of guys whom I have delt with on numerous occasions. Very helpful. Big company but still small enough to care

McGregor Amplification Ltd
Burtonwood Industrial Centre
Burtonwood
Warrington
Cheshire WA5 4HX

Telephone: 01925 223343
Fax: 01925 229873

Thanks for everyone's advice

As 'Sound in Gloustershire' has said, I'm a bit reluctant to lug around a second amp due to limited transport space. Its just that I think the Pro-12s lack some low end so I thought I might be able to use the McGregors to help out. I'll ring McGregor later today (thanks for the link djmatt) to save taking the speakers apart.

Slightly OT, there is some other gear available which I can borrow for free so that might be the solution (as I haven't got a budget for this one off gig).

This is what I have available:
2x Celestion SR1 mk2 (4ohm)
Celestion SRC2 controller
2x D&B E3 (16ohm)
2x D&B E-pac amp (capable of 16ohm, 8ohm and 4ohm)

As well as my Studiomaster 1200D amp, McGregors and Pro-12s.

What about connecting the E3 to the Studiomaster (or Epac?) and then a McG to the E3's output (using pins 2+/2- which is the sub output)? However, will this setup be able to handle a soul band setup with drums, keys, sax, vox, guitar, bass? Alternatively, can anyone recommend a better solution using the mish-mash of equipment available?

Thanks once again.