Question about the Quad 303 amp circuit

[Erocka2000]

Hey Folks,

I'm basically a complete layman when it comes to circuitry. I have a potential concept that I've been mulling around, but had some general questions regarding the Quad 303 amp. I know the original 303 used a circuit board but I was wondering if it's possible to replicate the circuit with a mostly point-to-point wiring scheme, without using a major circuit board. This may totally be impossible, but as I mentioned, I'm quite the layman.

Here's a photo of the circuit in question:

Quad 303 circuit diagram - large copy

 

[Michael Bean]

Do you have the actual board layout from the original PCB? That would be the best way if you're new to this, the layout is often times more important that the components used. And I wouldn't recommend traditional point to point because of that. You could try replicating the original PCBs on perfboard. It's pretty easy, but time consuming. I've used that method successfully many times.

Mike

 

[Erocka2000]

This was the best photo I can find of the board layout.

 

[Michael Bean]

You really also need to see the circuit traces too. If you can find a shot of the copper side, you'll be able to use the top and bottom views to replicate the circuit as designed, for greatest chance of success.

Mike

 

[Mooly]

The output triples in a 303 could be a stability nightmare with anything other than a good layout.

Replicating them with modern high speed devices also adds an unknown into the mix... but never let anything like that stop you trying. It may work out fine in practice.

 

[Erocka2000]

Just for a little context, the reason I'm asking this is I want to see if it's feasible to create an integrated amp using this circuit and adding a passive preamp to it. I don't have any schooling in circuits, so I have no idea if that's something that can even be done. It's more of a brainstorm idea.

 

[duncan2]

The company designed the Quad 303 to compliment and work properly with Quad electrostatics , that was their initial design priority .

That it works with moving coil loudspeakers was an additional plus.

As it stands its very stable , I owned one along with a Quad 33 .

Mooly has a point though as regards faster modern output devices.

 

[latala]

For about £12 you can purchase chinese clones of the power amp and power supply board
Very easy to use ! I have done this myself with 100% success and its a good amp
Trev

 

[Ian Finch]

Yes, you can even buy the PCBs with the resistors already fitted (there are lots of them!).
Just Google or use whatever search engine "Quad 303 PCBs".

 

[Mooly]

Just for a little context, the reason I'm asking this is I want to see if it's feasible to create an integrated amp using this circuit and adding a passive preamp to it. I don't have any schooling in circuits, so I have no idea if that's something that can even be done. It's more of a brainstorm idea.

In many ways the 303 is ideal for that because it has a much higher than usual (by today standards) of voltage gain of over 30db.

 

[Erocka2000]

Thanks for the advice, folks. I'm going to start looking into the PCBs that were mentioned.