There's a Quad 405 near me - should I buy it or not please?

[Newboy]

Quad amps (and pre’s, speakers etc.} are, IMHO, the best. Why?



A. They are simple, logical and repairable.



B. After all these years they can still hold their own with most others, many of which are horrendously priced.



C. AGI (Quad’s owners) are happily still wedded to the old ethos; ‘Don’t throw it out – we will repair it for you’ .



D. Their relevance in today’s ever more frenetic world is shown by the prices paid for an old fashioned ( in some respects outdated) unit and the various companies repairing/’upgrading’ them well into the 21st century. And the fact that there are many still using them & the amount of recent posts here and elsewhere.



When I bought my Quad in about 1985 one factor in my decision was that the shop had in an early Quad 22 & & Quad II set up being tested after repair.



This was one thing that decided me; also I remember my Headmaster at school had all Quad equipment.



Having said all that, I wonder if my 66 CD player would be repairable if its CD drawer fails?



Has the OP thought about a 606 Mk. 2, which is a very good amp indeed? I have one which I don’t use (my 306 does me fine). But it is in the attic & going nowhere!



Apologies for these after dinner ramblings!



Julian

 

[Martyn Miles]

Those are the sort of ramblings I like.
Makes a lovely change from cables...

 

[George J]

Just to add to Julian's post, two up. From personal experience with Quad at Huntingdon [head office], I can say that they go more than one step further than you expect with great service. They repair more or less anything that Quad have ever made. Their charges are very reasonable, and the people themselves are really helpful and positive.

I had a bit of trouble with a Quad II Forty, and received a whole replacement amp after the second fault happened. Since then I have had no problems, but only bought a few matched valves.

Wonderful service, and I have given up thinking of running any other type.

With best wishes from George

 

[Craig B]

So what's the maths involved in knowing this is suitable for an MC cartridge?

Sorry, I missed this question the other day.

The maths are mostly to do with signal multiplication; i.e. gain.

Typically, low output MC cartridges generate way less than 1mV output, whereas, typical MM types output anywhere from ~3mV to ~6mV. As with MM types, among the available low output MC (LOMC) cartridges there exists wide variations in output voltage; with both types, this is typically measured with reference to a 1kHz signal at 5cm/sec recorded velocity. The three MC modules that Quad provided offered different input sensitivity ratings to better match low, medium and higher output LOMCs, and therefore provide enough gain to both drive their amplifiers to near maximum and to provide a useful volume control range.

HOMCs, like the Denon DL-110 (1.6mV) and Dynavector DV-10x5 (2.5mV) models output anywhere from ~1.5mV - ~2.5mV (with reference to the same 1kHz Fq and 5cm/sec recorded velocity) and are therefore close enough to MM outputs to be used with standard MM inputs (although the volume control may have to be turned up a bit more, especially so with the DL-110, relative to when using a typical MM, for a similar level of volume).

The Quad 4A module that came with your 44, with its 200µV, 100R, 22nF, was intended as the typical median choice for use with a wide range of popular LOMC cartridges. A particularly low output LOMC might be better served by the 4B module with its lower input sensitivity of 100µV providing greater gain. Conversely, a higher than usual LOMC, would be better matched via the 4C module with its 400µV sensitivity.

Here is the Quad 34 & 44 Disc Input Modules sheet, from July 1984, with specific LOMC cartridge models matched to the three MC modules by letter.

 

[Hook]

Just noticed a nice looking 34 and 405-2 on Audiogon if anyone is interested. One owner trade-in, no scratches, original boxes. Dealer asking $900 for the pair.

 

[beammeup]

Is a Quad 405 a pure Class A implementation? Same question for the 303 and 306.

Also, I'm tempted to go to the German Quad Fest this coming September - held every two years - anyone else been? I'm fascinated how there can be a whole Weekend just on Quad kit.

 

[davidsrsb]

No, the 405 is Class A up to a few Watts and then the dumping starts, which is maybe Class C
The later models, 306 onwards, have a smaller pure Class A region and smoother transition to dumping.
The 303 is a conventional Class AB.

 

[beammeup]

OK thanks... I was just reading about the Quad 405 on Hi-Fi Pig (https://hifipig.com/the-quad-405-current-dumping-amplifier/), should I take heed of the following because I plan to use a simple passive pot before the Quad 405 ....?

"the 405 inverts the signal fed through it, relying on a Quad pre-amplifier which reverses the signal so that audio going through that op-amp is 180 degrees out. Therefore, if you don’t have a Quad preamplifier to reverse the signal into the 405 perhaps you should try swapping the negative and positive of both speaker terminals (- to +, + to -)"

If I were however planning to use the 44 pre, is there anything I should consider before connecting a digital source into it?

 

[ian r]

Good stuff. Saint Stevein Spain has just passed his Magnepans onto me ( yet to arrive ) but I wonder if its my time to get a 306 or 405 as they need a bit of shifting and my 110's are possibly not upto par... ?

I dont want to monoblok the naims again as that will undo another system. Agree re the repairing of kit is essential to avoid greenwash as per Apple and non servicable kit, so buying Quad is an ethical investement...

 

[Arkless Electronics]

No, the 405 is Class A up to a few Watts and then the dumping starts, which is maybe Class C
The later models, 306 onwards, have a smaller pure Class A region and smoother transition to dumping.
The 303 is a conventional Class AB.

A few milliwatts only in class A.

 

[Arkless Electronics]

OK thanks... I was just reading about the Quad 405 on Hi-Fi Pig (https://hifipig.com/the-quad-405-current-dumping-amplifier/), should I take heed of the following because I plan to use a simple passive pot before the Quad 405 ....?

"the 405 inverts the signal fed through it, relying on a Quad pre-amplifier which reverses the signal so that audio going through that op-amp is 180 degrees out. Therefore, if you don’t have a Quad preamplifier to reverse the signal into the 405 perhaps you should try swapping the negative and positive of both speaker terminals (- to +, + to -)"

If I were however planning to use the 44 pre, is there anything I should consider before connecting a digital source into it?

Absolute phase doesn't matter. Ignore it.

 

[Arkless Electronics]

Good stuff. Saint Stevein Spain has just passed his Magnepans onto me ( yet to arrive ) but I wonder if its my time to get a 306 or 405 as they need a bit of shifting and my 110's are possibly not upto par... ?

I dont want to monoblok the naims again as that will undo another system. Agree re the repairing of kit is essential to avoid greenwash as per Apple and non servicable kit, so buying Quad is an ethical investement...

If 405 then make sure it's MkII! 4R load and inefficient... 606 or 909 even better.

 

[ian r]

Is they as sexy as a 405? They newer stuff Im really not coming accross socially so never see or hear it.

Nothing past El 64's

I 'spect your right though.

 

[Arkless Electronics]

Is they as sexy as a 405? They newer stuff Im really not coming accross socially so never see or hear it.

Nothing past El 64's

I 'spect your right though.

I have zero interest in the appearance of hifi.. All my own amps, being designed and built by myself, rarely even have lids on the cases... if they even have cases! Most are circuitry just laying on the carpet.

 

[davidsrsb]

A few milliwatts only in class A.

Yes, the Class A output drives the load through 47R, its output voltage reaches 1.5V, the dumpers turn on through 3uH, so at low frequencies the dumpers take over at around 200mV into the speaker load

 

[Radfordman]

Yes, the Class A output drives the load through 47R, its output voltage reaches 1.5V, the dumpers turn on through 3uH, so at low frequencies the dumpers take over at around 200mV into the speaker load

Is this the same with the 405-2? I think my -2 when idling consumes something like 30 Watts. Seems a fair bit.

 

[Arkless Electronics]

Is this the same with the 405-2? I think my -2 when idling consumes something like 30 Watts. Seems a fair bit.

Yes. The main difference in the MkII is new thick film modules for the protection circuitry which relax the protection somewhat and allow it to properly drive 4R loads and a different op amp.

 

[Radfordman]

Yes. The main difference in the MkII is new thick film modules for the protection circuitry which relax the protection somewhat and allow it to properly drive 4R loads and a different op amp.

Thanks, but why is the idling power so much higher than say a Quad 303?

 

[davidsrsb]

The 303 is only a 45W amplifier. The higher supply rails for 100W and small size of the 405 mean it will get much hotter than a 303

 

[Radfordman]

The 303 is only a 45W amplifier. The higher supply rails for 100W and small size of the 405 mean it will get much hotter than a 303

I suppose that sort of makes sense, the 303 consumes about 13 Watts idling, the 405-2 just over double that.