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QUAD 44 PREAMP: UPGRADES

Robert said:
Ok here we go.

Firstly, the listener preference isn't the important thing so nobody should feel they've chosen the wrong track. Differences and magnitudes are what count here.

B - Straight CD rip made using EAC. Probably as 'reference' as we can get for this test.

A- Same CD but via the following:

- Meridian 200 Cd player
- Analogue output taken to CD input of Quad pre
- Output of Quad taken from power amp out and into ADC to create digital file.

So effectively we have a straight rip against a chain of three components including the full path of the Quad. All tone controls were set flat.

Mr T, Grenadier and Tony L (previously) have listened to these files and there are differences identified. Indeed there should be given the path as none of these devices are perfect. The differences are however described as small.
What's interesting are the magnitude of the difference and that was the reason for doing this in the first place. I think that comments such as 'strangle the music', 'seriously restricted bandwidth' and 'make singers sound like they are face down on the carpet' needed to be challenged and hopefully this test does just that.

For complex, active pre amps, these things are actually very decent even stock.
The one used for the test had a recap and uses OPA134/2134 devices but is otherwise standard. It uses the original 4066 cmos switching (now changed).
Click to expand...

Thanks for that Rob, and very interesting indeed - food for thought aplenty.

You know I'm very happy with the results I get from both my FM2 and FM3 tuners - both very capable of superb sound. I don't know where I went wrong with the 33 and 34 I owned way back in the day, but there is certainly very little wrong with your 34 - that much I do know. Perhaps the OPA 134 has made the difference? Having played around with those in the past and found them to be excellent devices (ultra low noise/distortion and designed for audio use) I'm inclined to think they are the answer here.

Davy
 
Brian said:
I'm not sure comments such as 'strangle the music', 'seriously restricted bandwidth' and 'make singers sound like they are face down on the carpet' really need to be challenged at all. These are ridiculous comments, I suspect the majority of readers would dismiss them, particularly the 3rd of those comments.

There are a multitude of solutions available for those people serious about listening to music in the home and we don't all like the same thing. I thought a Quad setup I heard was good, I'm sure others would consider it to be not good at all. It's not a big deal. I'm sure some people wouldn't like my TVC or valve setup but I like it and so does my wife, which is all that matters.

Well done for posting the files and giving people the chance to comment but I'm sure you realise people capable of holding an opinion such as the 3rd one above is unlikely to be changing their mind soon. I may be surprised of course...we shall see. Don't lose any sleep over it and just enjoy listening to your music.
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I agree Brian, but those comments do get made regularly and they stick.
I wouldn't attempt to change the mind of the person making comment number 3 but at least these threads now exist for people to listen for themselves.
They now have some actual samples of the real thing to consider alongside the 25 year old foggy anecdotes :)
 
Mr Tibbs said:
Thanks for that Rob, and very interesting indeed - food for thought aplenty.

You know I'm very happy with the results I get from both my FM2 and FM3 tuners - both very capable of superb sound. I don't know where I went wrong with the 33 and 34 I owned way back in the day, but there is certainly very little wrong with your 34 - that much I do know. Perhaps the OPA 134 has made the difference? Having played around with those in the past and found them to be excellent devices (ultra low noise/distortion and designed for audio use) I'm inclined to think they are the answer here.

Davy
Click to expand...

You might be thinking more of the 33 which does have a recognisable sound IMO.
It has tighter response shaping particularly at the bottom end and is noisier than the 44 and 34.

On the op amps, I found little difference on the line stages but you can really tidy up the phono stage with some modern low noise alternatives to the TL071, lower noise head amp transistors and a little relaxing of the RIAA LF toll-off.

The op amps and 4066 ICs are now socketed in my 34 so it would be possible to compare old/new/different devices.
No sockets in the phono section as a fast op amp is used there and it needs to be as snug to the pcb tracks as possible.
 
Robert's test reminds me of something I did in the 80's that surprised me.

System included Quad ESL 63's, Quad 405-2, 44, FM4. I plugged the headphone output of my Philips miniature stereo pocket radio thingy in to the 44 and the sound was very good, so good in fact that it was difficult to hear much difference switching to the FM4.

The feed from the Philips included it's output stage.
 
Rob - back then the only source I had was vinyl so I guess the Quad phono boards may have been at the root of my disappointment. Certainly the Meridian 101 pre I moved to was like switching on a light to the music and the discrete headamp/equalisation modules in the 101 were really very good indeed.

I think I can rest easy on this chapter now ;-)

Mr Tibbs
 
Mr Tibbs said:
Rob - back then the only source I had was vinyl so I guess the Quad phono boards may have been at the root of my disappointment. Certainly the Meridian 101 pre I moved to was like switching on a light to the music and the discrete headamp/equalisation modules in the 101 were really very good indeed.

I think I can rest easy on this chapter now ;-)

Mr Tibbs
Click to expand...

If you want a few needledrops from it just shout.
 
Brian said:
I tried downloading these files today but the links aren't working for me. Was wondering if anyone can have a go and see if it's a problem for them too.

Ta
Click to expand...

Just tried the first one, no problem, but if one has a slow connection, it will take some minutes.
 
Radfordman said:
Just tried the first one, no problem, but if one has a slow connection, it will take some minutes.
Click to expand...
Thanks. I'll take a look and work it out then. It's obviously a problem at my end.

Just tried it and it's working now. Bloody computers... :)
 
MEMOIRS OF A DIY HI FI NUT - Part XVIX​
QUAD 44 PREAMP: UPGRADES​

V

POWER MAD​

The mediocre Quad 44 internal power supply is feeble. It is barely adequate for not much else other than the reproduction of, say, choral or chamber music. I abandoned it.

I need a p/s that will do justice to the very wide variety of music in my collection. So…a massive and much better separate P/S, powered with a BIG transformer, was built. This giant I put into a large separate case. The new power supply is connected up to the back of the ‘44’ via a long CANARE cable and NEUTRIK XLR plug. It plugs into a new, professional, XLR socket that has a locking latch. The socket fits into the back of the Quad chassis very neatly. It is precisely the right size.

The pcb track was cut in one place to allow a switch connexion. To see the spec diagram please click on the LINK.

[url]http://www.flickr.com/photos/34514709@N07/5338850070/[/URL]

The old, original power supply can be switched back in just in case any subsequent owner is daft enough to prefer it. In retrospect I shouldn’t have bothered. The new p/s- with its high quality electrolytics, MIT multicap bypasses, high speed Hexfred ultra fast rectifiers etc.- delivers an altogether more realistic sound. A major step upwards.

To carry out this mod first i) remove one switched mains outlet socket- the one in the middle of the three identical sockets at the rear of the ‘44. Then ii) install the XLR socket in its place. The XLR socket I bought had only two screw holes, one in the top left hand corner, the other in the bottom right hand corner. A nut and bolt into the chassis via the upper left hand corner hole resulted in an insecure fastening that worked loose. I tried a self- tapping screw instead. This held well, screwed into the red plastic, insulated red mains isolation box.

The improvement in fidelity was striking and general right across the audio spectrum. Dramatic, satisfying, and especially impressive with respect to increased dynamic range in comparison with the original power supply.

BEFORE: capable of rendering a snowstorm
AFTER: capable of rendering a snowstorm, an earthquake and everything inbetween.

Bandwith was measured with a scope via the Tape Output module. It drops above 25K but now goes on till beyond 200KHz. A good improvement! [I would have preferred it to go on beyond 300KHz but I am getting on a bit, so may not be able to hear above 200KHz for much longer].

What next? The Beginning of The End.
______________________________________________
 
I listened to the files made available by Robert. So has my wife and my teenage son.

None of us can detect any difference between the files. If others can then fair enough, but there are 3 of us here who can't and that's using headphones directly from the Lavry DA10, so the signal hasn't been through my TVC or valve amplifier.

I assume we're all deaf.
 
eguth has lost it I am afraid, with his ultrasonic hearing I can only think he must be a superhero.
 
eguth said:
MEMOIRS OF A DIY HI FI NUT - Part XVIX​
QUAD 44 PREAMP: UPGRADES​

V

POWER MAD​

The mediocre Quad 44 internal power supply is feeble. It is barely adequate for much else other than the reproduction of, say, choral or chamber music. I abandoned it.
Click to expand...

This is a pre amplifier - the power supply works for all music or no music and it cannot pick and choose. It isn't feeble given the very light demands placed upon it.
 
Robert said:
This is a pre amplifier - the power supply works for all music or no music and it cannot pick and choose. It isn't feeble given the very light demands placed upon it.
Click to expand...

Just as, with the 'arcing due to low frequencies getting through the preamp' point, you are skating over the matter and missing the point.

No one suggested that the frequencies led to arcing; it is the excursions required by these that lead to contact with the high voltages and then arcing. So, as for the power supply, it is not a question of whether it "works or does not work at all".

The matter at issue is my view that the '44 p/s is

"...barely adequate for (etc.)..."

You have skated over and apparently missed this.

We shall have to agree to disagree on the description 'feeble'.

I agree, however, with you that it works. If not, please return it under guarantee.
 
honmanm

"...eguth it will be interesting to hear to what extent your mods were detail refinements vs wholesale re- engineering..."

Since you are one of the few on this thread that has expressed any interest in my mods you are deserving of a considered reply from me.

I assume that by "hear" you mean (roughly) "discover"- but just in case you (or anyone else) expects that I will post a needle drop of the complete mods I should say: i) I don't listen to them, ii) don't post any, iii) I believe that listening to needle drops is not the best way of carrying on demonstrations, and iv)that they can be misleading. v )Listening via needle drops adds many variables compared with a show, dealer or home demo. Leaving aside the effect of computers, for a start vi) the end part of the reproducing chain may vary substantially and critically; different headphones, different loudspeakers, different listening rooms.
 
No, I meant discover, i.e. hear as in hear what you're saying.

I'm not a big fan of needledrops either... computers are my working life and I don't trust them!

Needledrops are the best available way of sharing comparisons but the number of variables involved through A-D and D-A - even if using a proper monitoring system - is so great that I wouldn't feel qualified to draw any conclusions from them.
 
honmanm said:
No, I meant discover, i.e. hear as in hear what you're saying.

I'm not a big fan of needledrops either... computers are my working life and I don't trust them!

Needledrops are the best available way of sharing comparisons but the number of variables involved through A-D and D-A - even if using a proper monitoring system - is so great that I wouldn't feel qualified to draw any conclusions from them.
Click to expand...

Some derive pleasure from needledrops; indeed some seem to spend most of their time playing with them. If careful comparisons leading to conclusions that can be relied upon with regard (especially) to subtle differences are the aim, needle drops seem to me to be 'the flavour of the month' that will in due course be seen as a toy: fun to play with but not to be taken too seriously.
 
Eguth, You need to modify your post above as you have either lost it or miss quoted yourself. The human hearing goes up to about 17KHz or about 20Khz when at your best in your teens. most compact cassette tapes will struggle to get anywhere near flat at 18KHz.

If you are older then 15K may be the limit. To suggest you can hear anything up to 200K is ridiculous.

Mike
 
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