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Quad amplifiers 303, 306, 405 - pre-amps

legacylenslover

legacylenslover

pfm Member
morning all
I have a couple of different conversations going on this, and another forum, and Quad amps keep being suggested for my intended purpose (old Celestion speakers).
Rather than clog up the other thread, hope no-one minds me starting this one which has a slightly different emphasis.
Simple question - if I go the Quad amp route - are there recommended alternatives to using the Quad pre-amps which were originally intended for use with the specific amps?
To someone who has a basic grasp of pre/power amps - but has no 1st hand experience - are there particular factors I should consider (other than appearance, aesthetics, etc?). For the pre; passive or active (or does it depend on the amp?), input voltages?, I’m sure this is a case of ‘ I don’t know what I don’t know’.
any help much appreciated, if only suggesting I should keep to Quad pre-amps only.
Thanks.
 
If you don’t need a phono stage or tone controls all these amps work superbly well with a passive preamp IMO. I have a 303 with an Audio Synthesis Passion in my TV rig and it works superbly. Quads only need half a volt or so for full output so many active preamps have far too much output for them. If you want an active preamp for a phono stage a gain-reduced valve Croft is a very good match sonically. Quad’s own preamps are a lot better than people give them credit for if serviced properly, I’d not actually rule them out. I have a serviced late period 34 and it is pretty good, though the phono stage needs some minor modifications to really perform (reduce rumble filter, reduce capacitance).
 
I find my 303 is still too sensitive with my Allegri+, mine doesn't have an 'off' volume and on the first click it is just about normal listening levels, 2nd click is too loud for me. Still very nice sounding thing but it needs sorting as it isn't really liveable.
 
legacylenslover said:
morning all
I have a couple of different conversations going on this, and another forum, and Quad amps keep being suggested for my intended purpose (old Celestion speakers).
Rather than clog up the other thread, hope no-one minds me starting this one which has a slightly different emphasis.
Simple question - if I go the Quad amp route - are there recommended alternatives to using the Quad pre-amps which were originally intended for use with the specific amps?
To someone who has a basic grasp of pre/power amps - but has no 1st hand experience - are there particular factors I should consider (other than appearance, aesthetics, etc?). For the pre; passive or active (or does it depend on the amp?), input voltages?, I’m sure this is a case of ‘ I don’t know what I don’t know’.
any help much appreciated, if only suggesting I should keep to Quad pre-amps only.
Thanks.
Click to expand...


One reason to keep the quad preamps is that they have useful tone controls, in particular tilt and bass lift.
 
matt j said:
I find my 303 is still too sensitive with my Allegri+, mine doesn't have an 'off' volume and on the first click it is just about normal listening levels, 2nd click is too loud for me. Still very nice sounding thing but it needs sorting as it isn't really liveable.
Click to expand...

In fairness you have 105db Klipsch La Scalas! Even so I’m surprised as I found the Audio Synthesis stepped attenuators perfectly fine into the same speakers. I don’t know anything about the Allegri though, the AS certainly has very logical volume steps that makes it usable in a wide range of contexts.
 
legacylenslover said:
Thanks. I understand bass lift, but not sure what tilt means?
Could you explain if you have time?
thanks
Click to expand...

Tilt is a mix of a bass and treble control. Rotate the control one way and you get more bass and less treble. Rotate it the other and you get less bass and more treble.

The 'bass' control on a 34 boosts or cuts the lower part of the bass region. i.e. down in the string bass or big drums 'thuds and thumps' region. Helps to compensate for bass roll off in speakers or a low room 'boom' resonance, but in a broad-brush way.
 
One thing to note about the 303 relative to later designs is that it has an output network that can cause a resonant 'hump' in the response at low frequency. This may improve the sound with some systems, but degrade it with others. I suspect it was chosen to compliment the old ESL57.

The bottom (pun alert!) line here is that with the 303 you'll only know if you prefer it to other amps when you try it in your system. It may sound better/worse/same depending on circumstances. FWIW I like the 34 preamp as I think the controls are good. But I have tweaked mine which most people won't have done.
 
Jim Audiomisc said:
Tilt is a mix of a bass and treble control. Rotate the control one way and you get more bass and less treble. Rotate it the other and you get less bass and more treble.

The 'bass' control on a 34 boosts or cuts the lower part of the bass region. i.e. down in the string bass or big drums 'thuds and thumps' region. Helps to compensate for bass roll off in speakers or a low room 'boom' resonance, but in a broad-brush way.
Click to expand...
Many thanks for the explanation.
 
Tony L said:
In fairness you have 105db Klipsch La Scalas! Even so I’m surprised as I found the Audio Synthesis stepped attenuators perfectly fine into the same speakers. I don’t know anything about the Allegri though, the AS certainly has very logical volume steps that makes it usable in a wide range of contexts.
Click to expand...

It was fine with my other more modern power amp, just a bit OTT with the Quad! This is with vinyl as well, I haven't tried the DAC yet.
 
mandryka said:
Have a look at Page 12 of the manual

https://www.vintageshifi.com/repert...php?pdf=Quad-34-Owners-Manual-V1-17-pages.pdf

If you have an input with digital volume control, then remove all preamps and try the power amp working from the source directly connected. If you like that sound then consider passive preamps.
Click to expand...
Thank you. I hadn’t even considered this.
So, with me having my main source being a Raspberry Pi streamer with a digital volume control both in the main software and also attached to the Parametric Equaliser which I run permanently, in theory I could reduce the volume control to an absolute minimum and run streamer>DAC>power amp>speakers.
I know the digital volume works fine as i normally run -10dB on master volume, balancing it out with the volume control on my integrated.
I’d just need to be really careful to start with so as not to totally destroy my speakers with a slip-up.
Obviously everything changes if I use my TT though.
Thanks again.
 
I’ve tried the Tisbury, 34, 99 and Croft Micro 25 into a 306 over the last few months and everything sounded good. I didn’t do much systematic listening, and the speakers were new to me, but I can say the 99 sounded better to me than the 34, not sure where I’d put the Tisbury, Croft best overall. One thing about the 99 is that the MM phono is very good. If useability is a consideration it’s swings and roundabouts: the 99 has a remote and it’s good to be able to adjust sensitivity of each source without opening the thing up (MM/MC too) but overall I prefer the analogue controls of the 34.
 
I use a Quad 306 straight from a raspberry pi and a small topping e30 DAC, albeit I have some Rothwell attenuators in between to manage the 500mV sensitivity of the 306. This works extremely well as a setup. I could just set the digital volume on the E30 and leave alone, but I'm slightly paranoid and my son (while generally good as gold!) is occasionally prone to fiddling...
 
I used a passive pre with my QSP and 520 and found it a bit quiet with my 2Vrms line level sources into 8r speakers.

The 34 line level inputs provide a useful gain boost and a little bit of headroom for low gain programme material, as well as excellent tone and balance controls for in-room correction, but I'd suggest a DAC with volume control if you're digital only. A topping E30 directly into my QSP and a pair of Kef 103.2's was sublime and one of the rightest sounding setups I've had.
 
I’d use the correct period Quad preamps, but knowing that they always need to be refreshed.
I love the idea of listening to what Peter Walker was himself listening. Authenticity.
 
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