My dilemma is how I should go about doing a small rewire on my Randall RG50 Tube Combo. It has an internal 8 ohm speaker, and I have an outside speaker which is 8 ohms. On the back are an 8ohm and a 4 ohm output for an external speaker. The problem is that when plugging into the jacks on the back, it cuts the sound to the internal speaker.

My idea was to cut the wire of the internal speaker so that it can be wired to two jacks, and, when connected with a speaker cable performs in a factory way. However, when used in conjunction with the external speaker and attaching to the 4 ohm jack on the rear, the ampo would be outputting to both speakers at once.

Basically, would it be possible to wire the internal speaker so that It could be used in series with the external so that both are used at the same time? And if so, would it be benificial to attach an 8 ohm resistor to an input jack to attach to the internal speaker's jack when the load is going through the internal and external jack to prevent a transformer crash?

Sorry for the cryptic lingo, this appears to be the only way I know how to explain this. Any help will be greatly appreciated.

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O.K. I did a search and didn't come up with a picture of the back of the amp so with the following assumptions:

The combo speaker is wired directly into the amp chassis.

Either of the extension speaker jack sockets, when connected, disconnect the speaker wired to the amp.

The external speaker jacks are not meant to be used similtaneously. ie 8 and 4 ohm to different cabs.

If this is the case then I'd disconnect the combo speaker from the amp and using a splitter plug (two phono sockets from one phono jack - or a combination of plugs and wiring that will achieve a similar result) plug into the 4 ohm external speaker jack. Run the 8 ohm combo speaker from one half of the split and plug the other 8ohm component into the other side. They will be working in parallel and have a total impedence of 4 ohms.

Now because the external jack always turns off the line that runs to the combo speaker, you wont need to put a dummy load on it( and 8ohm, 50W resistors are easier said than done anyway).

If you really want to get the best out of your amp when running it only on the combo speaker you could then simply plug this speaker into the 8 ohm external speaker jack.

There are some more complicated circuits that could make this more idiot proof but keeping simple might achieve the same result too .

I'm curious about speaker and watts. If I have a 30 watt combo amp, what are the advantages/disadvantages to replacing the speaker with a 50 watt, 75 watt or 150 watt speaker? Louder? Earlier breakup?

The only way it will be louder, is if you replace it with a speaker that has a higher efficiency rating.

A vintage 30 has a rating of 100dB, where a G12M Greenback has a rating of 96dB. The Vintage 30 will be louder, and appear to be twice as loud. For every +3dB increase, the apparent loudness will double.

If you replace it with a higher wattage, the speaker won't breakup as fast. Some people like the sound of a speaker being pushed to it's limits, and some don't. It all comes donw to personal taste.

I'm going to include this information on the main post also.

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I've got a 412 400W carvin cab and its got two input jacks in the back one reading 'Mono Left' and the other "Ext. Right", does that mean if i plug something into the 'Mono Left' it will come out only on the left speakers? or vise versa? If so, is it safe to plug **** into both sides?

Ok so I have a 4 ohmn fender head.
And im buying celestions to put into a cab.
These speakers have options of either 4 ohmn or 8 ohmn.
so should I get the 4 ohmn or 8 ohmn.
Wiring these what would be the best solution?
What's the difference between mono and stereo when it comes to cabinets?
ok I think that is all.
Thank you.

whether to buy 4 or 8 ohm speakers depends on how many you have. if you only have 2 speakers, get 8 ohm, and wire them in parallel (+ to + and - to -). if you have 4, get 4 ohm speakers and wire them in series parallel (two pairs wired as above, with the + of pair A connected to the - of pair B and the speaker cable connected to the + of pair B and the - of pair A). sounds complicated at first, but go to http://www.avatarspeakers.com/wiring%20diagrams.htm to get all your questions answered.

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Thank you for the information
So should I still get 8 ohmn
If I am running two 2x12 cabs through the head?
And the diagrams are helpinful
Avatar was were I was actually planning on getting my speakers.

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you should probably get 4 ohm speakers and wire them in series. the diagrams on the page I link should show you how to wire it up. a 2x12 cab with 4 ohm speakers in series will be 8 ohms. two 8 ohm cabs in parallel makes 4 ohms - exactly what your amp wants.

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Nice ohms sticky... I have a question to ask - so you knowledgable people can help me win/lose a bet with my brother, at his request.

We have a Hughes&Kettner Matrix (solid state) head, which states "4 ohm min load" on the speaker outputs.

We also have a Marshall 1960 stereo cab which is switchable between Mono (4 or 16 Ohms) and Stereo (8 Ohms per side).

I say that it's safe to set the cab to 4 ohms mono and run the head through it but he disagrees.

He also says that we can run the head stereo through the cab at 16 ohms.

If you're wondering, the winner gets a Digitech Whammy that was "donated" to us.

P.s. I believe the regular cab for the H&K has 8ohms mono and 4ohms stereo

hey, this might sound weird...

would it be possible to go

120 watt head out to one 4x12
then out to a second 4x12 but with a delay pedal in the middle?

so...

head into one cab like normal
head into delay pedal, delay pedal out to second cab

would there be a risk of blowing something up!?
sounds weird, i know...

thanks!

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Welcome to Guitar Geek.

Unless I'm mistaken set the Marshall Cab at 4 ohms and use the H&K will give you the best result. Setting the Cab at 16 Mono will also work but won't be as loud. Using the cab in stereo will mean you only use half the speakers (per lead).

NO, and YES!

And welcome to guitar geek too.

Delay pedals work on mA, and mV, speakers work on A and V.

You will cook your delay pedal and not get any output. If you want to use a delay line it has to be in front of another power amp (then to the second cab). What I'm describing here is a stereo amp set up.

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thats what i figured i'd have to do..ohwell..
thanks man!

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