Installing a rear input on my Ampeg B2R

[RustInPeace90]

Hello

I have an Ampeg B2R in my rack rig but it annoys me having to keep an open slot for running a cable through to it so i have been thinking of installing a rear input on the amp so i can keep all the cables in the back of the rig and keep everything tidy.

Has any one on here ever done this before to an amp and has it worked properly? Also, is it dangerous in any way? (i'm guessing not as it's seems like it's simply a case of running some wires from the existing input and wiring them to the rear input in the same order?)

There seems to be plenty of room inside to place it and plenty of space on the back of the amp too. Would something like this need a switch involved on it to stop the other from working at the same time?

Thanks!

(photo from google of the inside of a B2R back -> front)

[icastle]

Nothing wrong with doing that.

A couple of things to remember though.

1) Make sure you put a cloth anywhere that swarf could get or you'll end up risking a short circuit.
I'd use it as a good excuse to get the hoover out and give everything a thorough (gentle) dust afterwards.

2) Your warranty (if you have one) will be void.

3) If you're running from the front to the back of the amp, you'll probably be needing to used shielded cable.

HTH

[KingBollock]

It looks like the socket is the kind with switched contacts. So if you wire the rear socket after the switched contacts the rear socket will be disconnected if there is anything plugged into the front. I am trying to think how you can do it the other way around, too, but can't get my head around it right now, too bloomin' tired. I need to figure it out, though, because I intend to do the same with my Peavey T-Max.

[RustInPeace90]

[quote name='icastle' timestamp='1424655697' post='2698883']
Nothing wrong with doing that.

A couple of things to remember though.

1) Make sure you put a cloth anywhere that swarf could get or you'll end up risking a short circuit.
I'd use it as a good excuse to get the hoover out and give everything a thorough (gentle) dust afterwards.

2) Your warranty (if you have one) will be void.

3) If you're running from the front to the back of the amp, you'll probably be needing to used shielded cable.

HTH
[/quote]

Oh aye i would be laying one of those anti-static sheets over the PCB boards to keep "swarf" (had to look up what that meant, guessed it was shavings/dust etc though) away and i definitely will be taking a hoover to it after. I have a mini USB powered one which should do the trick.

As for the warranty, it's out of warranty now anyway as it's about (so many) years old so I don't really mind doing this. If i think I may end up selling the amp at some point though, i will probably take it to a tech to be done professionally.

This is the cable i was thinking of getting for it, it's a 6 core plus 1 earth cable. I wouldn't know where to send the earth cable to though and it's probably pointless isn't it?

(photo for reference)



[quote name='KingBollock' timestamp='1424656697' post='2698888']
It looks like the socket is the kind with switched contacts. So if you wire the rear socket after the switched contacts the rear socket will be disconnected if there is anything plugged into the front. I am trying to think how you can do it the other way around, too, but can't get my head around it right now, too bloomin' tired. I need to figure it out, though, because I intend to do the same with my Peavey T-Max.
[/quote]

Yeah it has the contacts in the jack socket that (excuse the poor terminology here, i too am tired) "spread" open when the jack is inserted. What i was thinking of doing was running 4/6 wires from the solder terminals underneath the front input, lightly twisting them together (to keep them neat) and putting heat shrink tubing over them to keep the out the way then just copying the wire layout on to a jack socket that's the same as the front input one.

Again, please excuse me if none of this makes sense. I'm running on bugger all sleep and keep having "what if i do this..." and "maybe i should get that..." or "maybe i'll trade (insert piece) for (insert piece)..." so this is my main mind boggler tonight!

Thanks for the help so far both of you and if you think of anything KingB0ll0ck then please let me know.

[RustInPeace90]

edit: on closer inspection and comparison, it's a 4 pin mono socket so i've just ordered some 4 core shielded cable (£1 per metre) and a 4 pin chassis jack socket (£1.25) from Audio Spares. £2 postage. Should be here Wednesday.

In the mean time though, i still need to know how to do this haha

Edited February 23, 2015 by RustInPeace90

[KingBollock]

[quote name='RustInPeace90' timestamp='1424658716' post='2698893']
edit: on closer inspection and comparison, it's a 4 pin mono socket so i've just ordered some 4 core shielded cable (£1 per metre) and a 4 pin chassis jack socket (£1.25) from Audio Spares. £2 postage. Should be here Wednesday.

In the mean time though, i still need to know how to do this haha
[/quote]
You only need single core shielded cable, the same stuff that you would use for a guitar lead. You would run the core from the tip pin, and the shield from the other, both from the two pins after where the contacts spread. Then you would connect them to the pins before the spreading contacts on the rear socket, again core to tip and the shield to the other. This would make it so that the rear socket is disabled if something is plugged into the front socket, but it won't disable the front socket of something is plugged into the rear.

[RustInPeace90]

Correct me if I'm wrong here but from what you're saying, I need to use the pins connected to the 2 lugs that don't lift on the front input but to the 2 that do lift on the rear input?

Thanks very much KB!

Edit: is this the sort of cable you think I should use?
http://pages.ebay.com/link/?nav=item.view&alt=web&id=191502194984

Edited February 23, 2015 by RustInPeace90

[icastle]

[quote name='RustInPeace90' timestamp='1424658382' post='2698892']
This is the cable i was thinking of getting for it, it's a 6 core plus 1 earth cable. I wouldn't know where to send the earth cable to though and it's probably pointless isn't it?
[/quote]

You can use that cable, but you only actually need a single core plus shield.
The earth connection isn't optional, it won't work without it.

The earth cable is used to connect the 'sleeve' contacts of the two sockets together.
The cores are used to carry signals from the 'tip'contacts.
If you try and replace the earth braid with core cable you'll most likely get an awful hum.

[quote name='RustInPeace90' timestamp='1424658382' post='2698892']
Yeah it has the contacts in the jack socket that (excuse the poor terminology here, i too am tired) "spread" open when the jack is inserted. What i was thinking of doing was running 4/6 wires from the solder terminals underneath the front input, lightly twisting them together (to keep them neat) and putting heat shrink tubing over them to keep the out the way then just copying the wire layout on to a jack socket that's the same as the front input one.
[/quote]

I suspect it might not be that simple.
When you insert a jack plug it does two things, first up it connects the signal to the input of the amplifier, secondly it quite possibly removes a connection from something else (an anti thump ircuit for example).

Worst case scenario is that you 'might' need to stick a jackplug into whichever socket you aren't using.

If that's the case, and I never wanted to use the front socket again, I'd be inclined to slide a couple of thin plastic shims between the socket contacts and 'arms' to break that front socket connection.

[KingBollock]

[quote name='icastle' timestamp='1424695280' post='2699177']


I suspect it might not be that simple.
When you insert a jack plug it does two things, first up it connects the signal to the input of the amplifier, secondly it quite possibly removes a connection from something else (an anti thump ircuit for example).

Worst case scenario is that you 'might' need to stick a jackplug into whichever socket you aren't using.

If that's the case, and I never wanted to use the front socket again, I'd be inclined to slide a couple of thin plastic shims between the socket contacts and 'arms' to break that front socket connection.
[/quote]
I did wonder about that, but then, for some reason, chose to not consider it. Would one way around it be to disconnect the post break lugs of the front socket from the circuit board, then wire them to the pre-break lugs on the rear socket. Then go from the post break, rear lugs, back to the front, into the holes left vacant by the front socket?

Does that make sense?

[icastle]

[quote name='KingBollock' timestamp='1424715149' post='2699538']

I did wonder about that, but then, for some reason, chose to not consider it. Would one way around it be to disconnect the post break lugs of the front socket from the circuit board, then wire them to the pre-break lugs on the rear socket. Then go from the post break, rear lugs, back to the front, into the holes left vacant by the front socket?

Does that make sense?
[/quote]

I had to read it three times, but yes, that would make sense.

The biggest problem would be breaking the joint between the socket and the pcb, not impossible but a bit fiddly.

[KingBollock]

[quote name='icastle' timestamp='1424738395' post='2699984']
I had to read it three times, but yes, that would make sense.
[/quote]
That's a relief!

[Dad3353]

I'd suggest simply running a short length of screened 'mic' cable between the present jack solder joints and the rear socket pins. No-one is going to be plugging into both at once, and, even if they did, what harm could it do..? Sometimes simple is best.
The cable shown in the link would work, but is overkill for the job. Have you not a jack lead with a busted jack that you could cannibalize..? You don't need vintage, cloth wrapped stuff; that's for pimping guitars. It'll work, but there are cheaper solutions, just as efficient.
Just my tuppence-worth.

[KingBollock]

[quote name='Dad3353' timestamp='1424739263' post='2699991']
I'd suggest simply running a short length of screened 'mic' cable between the present jack solder joints and the rear socket pins. No-one is going to be plugging into both at once, and, even if they did, what harm could it do..? Sometimes simple is best.
The cable shown in the link would work, but is overkill for the job. Have you not a jack lead with a busted jack that you could cannibalize..? You don't need vintage, cloth wrapped stuff; that's for pimping guitars. It'll work, but there are cheaper solutions, just as efficient.
Just my tuppence-worth.
[/quote]
Hmmm, well, there is that...

[RustInPeace90]

[quote name='icastle' timestamp='1424695280' post='2699177']
You can use that cable, but you only actually need a single core plus shield.
The earth connection isn't optional, it won't work without it.

The earth cable is used to connect the 'sleeve' contacts of the two sockets together.
The cores are used to carry signals from the 'tip'contacts.
If you try and replace the earth braid with core cable you'll most likely get an awful hum.
[/quote]

On that advice i ordered some of the single core stuff with the braided shield round it. Bought 2 x 2ft lengths of it so that should do the job and i'll have spare just in case!

[quote name='icastle' timestamp='1424695280' post='2699177']
I suspect it might not be that simple.
When you insert a jack plug it does two things, first up it connects the signal to the input of the amplifier, secondly it quite possibly removes a connection from something else (an anti thump ircuit for example).

Worst case scenario is that you 'might' need to stick a jackplug into whichever socket you aren't using.

If that's the case, and I never wanted to use the front socket again, I'd be inclined to slide a couple of thin plastic shims between the socket contacts and 'arms' to break that front socket connection.
[/quote]

Hmm, well what i may try and do is to attach the wire to the 2 lugs on the front jack then just touch them against the socket i'd be using for the rear input but have my cable plugged in to see if there's a signal. If that doesn't work, i'll try it against the other 2 lugs then failing that, stick something in the front jack to break the connection.

[quote name='KingBollock' timestamp='1424715149' post='2699538']
I did wonder about that, but then, for some reason, chose to not consider it. Would one way around it be to disconnect the post break lugs of the front socket from the circuit board, then wire them to the pre-break lugs on the rear socket. Then go from the post break, rear lugs, back to the front, into the holes left vacant by the front socket?

Does that make sense?
[/quote]

I think i know what you men by that, again i'm stupidly replying when i'm desperately tired which is never a good idea. As said in the previous bit replying to icastle's suggestion, i'll try touching some the wires on the jacks together to see which way will work.

What i'm hoping for is what you said about before where putting a jack in to the front input would disable the back input but not the other way round just for ease of use if i'm ever lending my amp head out to other bands at gigs and they can just run their cables in to the front of my amp without unplugging my cables from the back. (i don't usually like letting others use things like my Sansamp and compressor for obvious reasons).

With a bit of luck all the bits will be here by friday so i'll be able to report more by then.

[RustInPeace90]

[quote name='Dad3353' timestamp='1424739263' post='2699991']
I'd suggest simply running a short length of screened 'mic' cable between the present jack solder joints and the rear socket pins. No-one is going to be plugging into both at once, and, even if they did, what harm could it do..? Sometimes simple is best.
The cable shown in the link would work, but is overkill for the job. Have you not a jack lead with a busted jack that you could cannibalize..? You don't need vintage, cloth wrapped stuff; that's for pimping guitars. It'll work, but there are cheaper solutions, just as efficient.
Just my tuppence-worth.
[/quote]

Hey dude, sorry for ignoring your reply in my last post, i didn't see the last 3 posts on here until just now. I don't have any shielded cables around that i can break up at the moment so i've just ordered some. It's only £3.75 so it's not too expensive and if it'll do the job then i don't mind paying it.

If i'm reading what you said properly about where to attach the wires then i think that's what i was thinking of doing to test it out. But either way, i shall definitely bare this in mind for when i have a go at it.
Thank you for the advise

[Dad3353]

[quote name='RustInPeace90' timestamp='1424740809' post='2699999']
Hey dude...
[/quote]
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[icastle]

Let us know how you get on, I'm sure you're not the first person to have wanted to do this and this thread might be valuable to someone ele in the future.

[RustInPeace90]

When I get to doing it (sometime this weekend looks more likely) I'll post some pictures as I go along. Y'know, as long as I don't kill myself some how or feck my amp up royally!

Thanks for all the tips and pointers KB, icastle & dad3533

[Dad3353]

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