Quad 303 amplifier & Quad 33 Pre-Amp

[rubber_jonnie]

So, this is a slightly different post for me, as it's audio related, plus somewhat nostalgic as it's my Dad's kit that I inherited in 2022 when he died.

I'm going to start with the Quad 303 power amp, as it is a big brutal piece of industrial design, but with very nice construction.

Just 8 screws allow the seemingly bullet proof covers to be removed, revealing this:

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And yes, the transformer forms a large proportion of the weight of the unit!

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The PCBs can be detached at one side allowing them to flip down:

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Construction is point to point wiring and it is just gorgeous, especially with the lacing on the wiring harness.

All the caps on the PCBs look fine, there is just a bit of a scorch mark where a resistor gets hot on one of the PCBs, but given my Dad ran it for probably 30 years off and on, I think it'll be ok for the limited use it'll see in the future.

As for the main caps, there are 4 of these bad boys:

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Yep, 100v 2000uF. I will check for discharge resistors before I do any more fiddling, but given they haven't seen power for many years I doubt there is any charge stored, but you can never know...

Hopefully I can have a look at the pre-amp later today and I'll post pictures when I do. I do also have my Dad's Thorens TD125 MkII record deck, but I'm waiting for a service kit to arrive for it before I start pulling it apart, so will post separately.

I'm also waiting on a variac because I want to power this combo up gently. I suspect it'll be fine, especially since the components seem to be high quality, but you never know.

[chronicthehedgehog]

Nice. I thought about buying Quad a few years ago when I wanted a vintage hifi - as it looks cool

I bought 70s Sansui in the end as it showed up at a good price first.

Should be a beast

I hope you've got some BIG speakers to go with it I've read that 70s Celestions go nicely with Quad kit.

Thorens are great decks. I've got a 160

[rubber_jonnie]

Nice. I thought about buying Quad a few years ago when I wanted a vintage hifi - as it looks cool

Yeah, they look great, and in fact Quad have released a modern version of the 33/303 combo and they've kept the styling but modernised and they look just as amazing.

I bought 70s Sansui in the end as it showed up at a good price first.

That name rings a bell from back in the day! I have a Technics micro system from the late 80's early 90's as well that I need to have a close look at too, all separate components tied together with ribbon cables.

Should be a beast

Pretty sure it will be

I hope you've got some BIG speakers to go with it I've read that 70s Celestions go nicely with Quad kit.

Sadly I don't. Dad had a pair of AR-7 speakers, probably equivalent to some comparable Celestion, but unfortunately the speaker cones had disintegrated and whilst I suppose they could have been repaired, it wasn't something I really wanted to get into.

I'd love a pair of Quad Electrostatics, but they are super expensive. I'll have to manage with the cheap speakers I have for testing.

Thorens are great decks. I've got a 160

My dad's lived in the lower polystyrene packing for ages until he got the plans for the wooden case and my uncle built it for him. It's lasted a long time and will last many more years I expect. Very good decks for sure.

The tone arm mechanism on the 160 looks very similar to the 125, but the controls are a lot different.

[rubber_jonnie]

OK, so I've had a look at the Quad 33 pre-amp this morning and I'm a bit wowed by its construction.

First off the internals are on rails, so once you remove the two screws at the back, the internals just slide out:

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Revealing more beautiful point to point wiring, plus some lovely little PCBs that plug into the main boards for easy maintenance. I'm shocked how little dust was inside:

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Construction is just beautiful. I pulled all the PCBs and cleaned the contacts with IPA followed by a cotton bud with a little Electrolube.

As a bonus I found the bag with all the cables and I have everything I need to hook up the record deck:

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Mains goes into the Pre-Amp (33) and then there is a dedicated cable feeding mains from there to the power amp (303), and there is a dedicated audio lead from the 33 to the 303. There is also a dedicated turntable input for which I also have the phono leads.

You may also have noticed the 2 PCBs hanging out of the back, these are turntable and tape deck adapter boards which allow you to customise your audio depending on the device you are using for input. I've cleaned their contacts too.

So I am waiting for some speaker wire now and banana plugs, plus the variac I've ordered since I want to bring it all up gently after such a long period of standing.

Given the quality of construction and components I think it'll be OK.

[rubber_jonnie]

Well, the variac arrived this morning, and once it was up to room temperature I plugged in the Quads. Yes, it's not lost on me that there are only two of them...

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I took a few hours and started at 30v and slowly ramped up to 220v, all the time monitoring for failures, of which there were none.

Next up I need to hook up my speakers and my signal generator to an input and test each channel. Fingers crossed

[HigashiJun]

The pre-amp is really well constructed for sure.

Love all that neat wiring.

I didn't know this brand before your post.

[rubber_jonnie]

The pre-amp is really well constructed for sure.

Love all that neat wiring.

I didn't know this brand before your post.

Yeah, it really is beautifully wired and looks like new, especially in the pre-amp.

The company still exists BTW and has a modern equivalent to these.

What you should take a look at is the Quad Electrostatic speakers, they are something else.

[HigashiJun]

What you should take a look at is the Quad Electrostatic speakers, they are something else.

Yes, I have just checked.

I can get a set of two here (not in a good state though) for around £588...

Nice example of seventies kitsch.

[CiH]

In the seventies, my dad was a good friend of the local high-end Hi-Fi shop owner.

He got to try out lots of gear.

Highlights included the Dalek-like KEF 105 speakers, but the Quad amp-pre amp combo was the most enduring part.

[rubber_jonnie]

What you should take a look at is the Quad Electrostatic speakers, they are something else.

Yes, I have just checked.

I can get a set of two here (not in a good state though) for around £588...

Nice example of seventies kitsch.

As speakers go they are quite epic