Have I wired this right?

AlexHunter

'73 Pro Reverb
1 original Oxford speaker, 1 WGS 12C - both 8ohm (as far as I'm aware).
Having not changed speakers before, have I wired it correctly in parallel for a 4 ohm load?

'pologies for the blurry pic.

DartmoorHedgehog

They are definitely wired in parallel, so if they're both 8 ohm speakers the cab will be 4 ohm, yes.

Might be worth checking the polarity and make sure they're in phase with each other (easiest way is stick a 9v battery across the leads and make sure both the speakers move the same way).

ICBM

Yes, but you can/should make a much neater job of the wires than that! Not just so it looks pretty, but because it reduces the chance of something getting snagged on one and pulling it off. The wires should be wrapped at least as neatly/tightly as the two going to the original speaker. Do it by physically moving one around the other, not twisting.

ecc83

ICBM said:

Yes, but you can/should make a much neater job of the wires than that! Not just so it looks pretty, but because it reduces the chance of something getting snagged on one and pulling it off. The wires should be wrapped at least as neatly/tightly as the two going to the original speaker. Do it by physically moving one around the other, not twisting.

Yes and I always cable tie the wires to the speaker basket so that if they do get snagged you don't rip the pigtails out of the voice coil. That would mean a re-cone or bin job!

Bit surprised IC has not suggested solder instead of the push on receptacles but in any event make sure they are nice and firm. If they are, no problem IMHO.

Dave.

jpfamps

I would also check the phasing with a 9V battery.

ICBM

ecc83 said:

Bit surprised IC has not suggested solder instead of the push on receptacles but in any event make sure they are nice and firm. If they are, no problem IMHO.

I would have, but first things first, get it wired neatly .

For what it's worth, this week one of my jobs was a cheap Ampeg bass combo which was fluctuating in volume… I'll give you a guess what the cause was .

ESchap

ecc83 said:

ICBM said:

Yes, but you can/should make a much neater job of the wires than that! Not just so it looks pretty, but because it reduces the chance of something getting snagged on one and pulling it off. The wires should be wrapped at least as neatly/tightly as the two going to the original speaker. Do it by physically moving one around the other, not twisting.

 

Bit surprised IC has not suggested solder instead of the push on receptacles but in any event make sure they are nice and firm. If they are, no problem IMHO.

Dave.

One row at a time gentlemen please ....  you don't want to confuse the message ...  :P

AlexHunter

both speakers move in with the 9v battery test, that about right?

DartmoorHedgehog

AlexHunter said:

both speakers move in with the 9v battery test, that about right?

Yes, if they both move the same way they're in phase - that's what you want. Some people say there's a difference in sound with them moving one way vs the other way, but as long as they're both the same that's the main thing.

ecc83

DartmoorHedgehog said:

AlexHunter said:

both speakers move in with the 9v battery test, that about right?

Yes, if they both move the same way they're in phase - that's what you want. Some people say there's a difference in sound with them moving one way vs the other way, but as long as they're both the same that's the main thing.

The standard (in UK at least!) is that + on the jack tip causes the cones to move "out" that is away from the basket. This means that at least multiple cab arrays will aid each other in phase. I am not aware however if there is any standard for making all guitar amps net inverting or non-inverting?

Dave.

ecc83

ICBM said:

ecc83 said:

Bit surprised IC has not suggested solder instead of the push on receptacles but in any event make sure they are nice and firm. If they are, no problem IMHO.

I would have, but first things first, get it wired neatly .

For what it's worth, this week one of my jobs was a cheap Ampeg bass combo which was fluctuating in volume… I'll give you a guess what the cause was .

Ampeg? Imerican aren't they?

Dave.

ICBM

ecc83 said:

The standard (in UK at least!) is that + on the jack tip causes the cones to move "out" that is away from the basket. This means that at least multiple cab arrays will aid each other in phase. I am not aware however if there is any standard for making all guitar amps net inverting or non-inverting?

Not at all. There are even some two-channel amps where the channels are opposite polarities, both traditional parallel-channel ones like Fender BF reverb models, and channel-switchers like Mesa Dual Calibers.

ecc83 said:

Ampeg? Imerican aren't they?

The company, yes. This amp was made in China.

I actually suspect the problem was the crimped contact between the connector and the cable, rather than between the connector and the speaker terminal.

ecc83

ICBM said:

ecc83 said:

The standard (in UK at least!) is that + on the jack tip causes the cones to move "out" that is away from the basket. This means that at least multiple cab arrays will aid each other in phase. I am not aware however if there is any standard for making all guitar amps net inverting or non-inverting?

Not at all. There are even some two-channel amps where the channels are opposite polarities, both traditional parallel-channel ones like Fender BF reverb models, and channel-switchers like Mesa Dual Calibers.

ecc83 said:

Ampeg? Imerican aren't they?

The company, yes. This amp was made in China.

I actually suspect the problem was the crimped contact between the connector and the cable, rather than between the connector and the speaker terminal.

Ah! Well, nothing's good if it ain't done right!

Dave.

ICBM

ecc83 said:

Ah! Well, nothing's good if it ain't done right!

Exactly, which is why I did it right.

Snip, strip, wrap, solder.