Quad 303

Phil_aka_Pip

I believe a 303 has an i/p sensitivity of 0.5V

Am I right in thinking that if I were to use one as a studio monitor amplifier I would need a potential divider across the o/p from a Studiomaster Series V desk?

57Deluxe

I remember my Father had one of the very first Quad 303s... it was not as quiet as he wished so we drove all the way to Huntingdon in our Mini from Surrey (pre M25 of course) to have it put on test at Quad's Labs for the day and waited for it... we had chicken and chips in a local pub restaurant... we were the only people there! Oh and my Johnny Apollo of course!

They told him was within spec... later he developed Tinitus!!

      (Quad testing was very thorough!)

http://www.wildtoys.com/blog/2009.07.17-JohnnyApollo.jpg

Phil_aka_Pip

I've got one and it is a most wonderful Hi Fi amplifier, although I do know someone who used them for PA & disco use.

I've never noticed my 303 to be noisy, except for needing an i/p cap to be replaced when it went grumbly. Word has it that the 33 preamp could have been quieter.

ChrisMusic

I ran a Quad 405 into a pair of 15" Tannoy Monitor Golds, from an Amek desk, and I don't recall any issues, or needing to pad it.  It was a very long time ago though, way before Harman International screwed Amek.  Quad are great amps IMO (great desks, and fantastic monitors too).  Not sure if that helps much though.

ecc83

The 303 does indeed have a sensitivity of 0.5V for full, 45W output and they were, and are still are very good amplifiers.

However, 45watts is not a lot into modern compact speakers which is one reason Quad developed the 100Wpch 405 and its chill'n.

If you do use them to dive passive monitors the best solution IMHO is to put two 10k log pots in a tin close to the PA and having setup the drive from the desk for "normal" levels, set the pots to give the accepted, "calibrated" 85dB SPL at the sweet spot.

Do be aware also that some 303s had voltage limiting resistors in them for use with the ESL.

Dave.

Phil_aka_Pip

@ecc83 fanx Dave, I'm expecting it to drive a pair of Tannoy Reveal monitors that I bought from Jalapeno a few years back.

EDIT does anyone sell a made up DIN connector for a 303 i/p that has either a stereo 1/4" jack or a pair of 1/4" mono jacks on its other end?

ecc83

Phil_aka_Pip said:

@ecc83 fanx Dave, I'm expecting it to drive a pair of Tannoy Reveal monitors that I bought from Jalapeno a few years back.

EDIT does anyone sell a made up DIN connector for a 303 i/p that has either a stereo 1/4" jack or a pair of 1/4" mono jacks on its other end?

I am sure Rob of Kabl could make you one up. If not your best bet is a DIN to 2x RCA and a pair of RCA to jack plug adapters.

But if you are going to go for an attenuator all can be wired out from that?

FYI The Quad DIN input is as per the regs (we would expect nothing less of Mr W!) . Pin 1 left hot, pin 3 right hot, pin 2 common.

Dave.

Phil_aka_Pip

Well, the ebay 303 is now mine. The plan to resurrect the studio progresses one further stage ...

ChrisMusic

Congratulations, that's a nice amp.

Good luck with the studio, that's something I am looking forward to doing again one day.

ecc83

I have just found a specc' for the Tannoy Reveal 601P and the Quad is just under the suggested PA requirement of 50W "programme" 100W pk.

Nonetheless the 601P has a sensitivity of 89dB/W/mtr and so 45W should deliver 105dBSPL at 1mtr.

If you were to calibrate for an 83dBish normal level that gives you a ~20dB loudness headroom so unless you are a serious headbanger you should be fine!

Dave.

Phil_aka_Pip

Cheers Dave. I was driving the Tannoys with a Samson Servo 200 but it broke and @ICBM didn't think it was worth fixing. I don't think I will have the requirement (or the liberty) to crank the monitoring system, so I'm still happy to try it. The pots on the Samson were kept at 2/3 of their travel anyway. There are always other uses for a 303, being a bargain at £87.

Phil_aka_Pip

It has just arrived, nicely packed. He also bunged the interconnects in with it, which makes my life a lot easier. Looking forward to trying it out ...

Phil_aka_Pip

ecc83 said:

I am sure Rob of Kabl could make you one up. If not your best bet is a DIN to 2x RCA and a pair of RCA to jack plug adapters.

Dave.

Perhaps I should pm him: what's his handle?

ChrisMusic

Calling KaBL, y'all need to talk to @RobDavies   

Phil_aka_Pip

ChrisMusic said:

Calling KaBL, y'all need to talk to @RobDavies   

fanx Chris!

ChrisMusic

No worries Phil.   I presume you know that if you click his name the the @ thingy I posted, it will take you straight to his profile page so you cam PM directly him if you wish...

Phil_aka_Pip

This weekend I tried the Monitor o/p of the Yamaha AW16G workstation into the Quad 303, driving the passive Tannoy monitors. It worked very nicely.

Then I tried the L/R o/p of the Studiomaster Series V 16:8:2 desk into the 303. This is the configuration I would like to use, with the workstation o/p going to a pair of channels on the desk.

The desk drives the 303 much harder than does the workstation. You only need the faders up to the -20dB mark for a VERY LOUD sound out of the Tannoys. 

ecc83

Phil_aka_Pip said:

This weekend I tried the Monitor o/p of the Yamaha AW16G workstation into the Quad 303, driving the passive Tannoy monitors. It worked very nicely.

Then I tried the L/R o/p of the Studiomaster Series V 16:8:2 desk into the 303. This is the configuration I would like to use, with the workstation o/p going to a pair of channels on the desk.

The desk drives the 303 much harder than does the workstation. You only need the faders up to the -20dB mark for a VERY LOUD sound out of the Tannoys. 

So, you need attenuators in each line to the Quad. Now you could just use fixed resistors but might I suggest a pair of Maplin's multi-turn trimmers in a tin?

That way you can set the desk fader to "0" and tweak the Quad to deliver the calibrated 83dBC you know you should be getting!

Dave.

Phil_aka_Pip

@ecc83 Makes sense. You mentioned 10klog before

ecc83

Phil_aka_Pip said:

@ecc83 Makes sense. You mentioned 10klog before

Yo! That would be for an extra control. I was thinking now of a set and forget attenuator.

Dave.

Phil_aka_Pip

ecc83 said:

Phil_aka_Pip said:

@ecc83 Makes sense. You mentioned 10klog before

Yo! That would be for an extra control. I was thinking now of a set and forget attenuator.

Dave.

Well, they do various preset pots. Round things that presumably you twiddle with a screwdriver from above, and square things that your screwdriver would have to be parallel to the pcb to operate. 10k strikes me as being quite a low value - I'd have guessed something like 500k - but you are way more expert tham I am.