Creating a single channel Quad 303 with a Pot

[Goochtoucher]

Hi guys,

First of all: I hope you all had a good christmas.

Secondly: I need some help as I am pretty clueless when it comes to wiring electronics and such.

I am looking to turn my 2-channel Quad 303 into a single channel 90W 4Ohm amplifier by hooking up both channels in parallel. I have done a ton of research and although some people think this is a bad idea, the quad manual states that it is possible and many people attest to the 303's tank-like indestructibility. So I am going to try it.

I know I need a 5k Ohm Potentiometer, but I have absolutely no idea how to attach it or where it goes and I am particularly confused about how I am supposed to know what levels to adjust it to.

Both channels have to be the same output to reduce stress on the amp correct? So how do I know that they are both the same level? Plug the Potentiometer in and set it to the highest setting, guaranteeing it is the same? Do I leave the Pot in there when I am done? Do I need one Pot for each channel?

As you can see, I am in the dark, but eager to learn so if you could give me a hand that would be brilliant. Also if you could keep the technical jargon to a minimum (unless I need to know what it is specifically) then that would be great. It makes it easier to take in and understand that way.

Cheers,

Gooch

 

[markw]

Deja vu all over again?

Didn't we just go through all this right here??

 

[Goochtoucher]

Didn't we just go through all this right here??

That pointed me to what I needed. Nothing in there tells me how to actually use the potentiometer or any of that. All I found is how to adjust the pot in a circuit, but couldn't find anything relating to creating a parallel ciruit on an amp. I just really don't want to screw it up as I have been warned constantly on the internet that if I do it wrong it will well and truly destroy my amp. One of the channels trying to run the other or something like that?

 

[markw]

The last I heard you were going to have an experienced tech with the proper equipment do it. If you want guaranteed results, that's the way to go. You obviously don't grasp what you're doing here.

 

[Goochtoucher]

The last I heard you were going to have an experienced tech with the proper equipment do it. If you want guaranteed results, that's the way to go. You obviously don't grasp what you're doing here.

I contacted Quad and they said that they won't do it, but would give me the instructions on how to. I have those instructions and it says I need a potentiometer a 5k Ohm one to be precise, but the instructions are rather lacking. If I do not think I am capable of doing it then I will not do it, but I need all the relevant information before making a decision.

Your advice is to get a technician to do it: the only one I found who will do says it will cost £550. If I had that money to spend I would sell my 303's and buy a Quad 909. So the next option is to do it myself. I am not some naive moron who thinks that it is going to be easy and that I will not have to research it first. However, I know my capabilities and I know that within those limits, I am capable of learning intricate things like this; as long as I have all the information.

I respect the fact that from your perspective it may seem an impossible task for me to do it, but that is not helping me. If you could answer some of the questions I posted in my first post then I would be extremely grateful.

I do not understand this sentence "Set the amps to a null of output" and I feel like this may be they key to understand how to do it.

 

[Goochtoucher]

I must apologise, I did not see the last few comments in the previous thread, I clearly abandoned it too early for some reason.

Which means this thread is fairly pointless. I will contact Quad again. If a Mod could delete this thread it would be pretty useful. It offers Zero information.

 

[TLS Guy]

Hi guys,

First of all: I hope you all had a good christmas.

Secondly: I need some help as I am pretty clueless when it comes to wiring electronics and such.

I am looking to turn my 2-channel Quad 303 into a single channel 90W 4Ohm amplifier by hooking up both channels in parallel. I have done a ton of research and although some people think this is a bad idea, the quad manual states that it is possible and many people attest to the 303's tank-like indestructibility. So I am going to try it.

I know I need a 5k Ohm Potentiometer, but I have absolutely no idea how to attach it or where it goes and I am particularly confused about how I am supposed to know what levels to adjust it to.

Both channels have to be the same output to reduce stress on the amp correct? So how do I know that they are both the same level? Plug the Potentiometer in and set it to the highest setting, guaranteeing it is the same? Do I leave the Pot in there when I am done? Do I need one Pot for each channel?

As you can see, I am in the dark, but eager to learn so if you could give me a hand that would be brilliant. Also if you could keep the technical jargon to a minimum (unless I need to know what it is specifically) then that would be great. It makes it easier to take in and understand that way.

Cheers,

Gooch

If you attempt this, then you need to make a professional job of it. I have no idea of your skills.

Now you will need to carefully find a spot on the end panel that has the input connection. You will need to disassemble the amp, so you can drill a hole for the pot safely. To drill the hole you need a hammer and punch and a very hard drill bit, preferably in a drill press. Then you need to round it out with a special machine bit, to get of the burrs and make it perfectly round..

You will also need to drill holes in the same fashion for RCA sockets.

Thenb you need to solder the connections according to the diagram in the previous post.

To balance it, you will need a signal generator and a high impedance amplified meter, not a cheap meter.

It is important the pot be inside the case, or you will have a lot of induced hum.

If you can do this you will be fine. If you don't have the correct tools already, then $550 is cheap.

Your original 303 still needs service I think.