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QUAD 44 PREAMP: UPGRADES

I am a very keen Quad user, but I just can't get on with the preamplifiers. My quad 33 had a poorly balanced volume control. it was too sensitive for 2 volt output sources and the useful bits re record playing were redundant. The looks were great.

My 44 that I acquired is very similar. I keep it for sentimental reasons only.
 
Nice to see that sentiment still has a place in hi fi. I agree with your findings on the '44 volume control, and will make what I hope is an appropriate remark about it in what I hope is the appropriate place.

Somehow, somewhere I feel that squash balls have a place in the improvement programme for the '44, but I just haven't found find it yet.
 
eguth said:
“…A Quad 44 measures out at +/-0.25dB 20Hz-20KHz on line with the LF -3dB point at 10Hz.*..”

Following your asterisk you say you have measured NOT a ’44, but a ’34. I have carefully avoided any mention of ‘34s, because they are not ‘44s and there are differences besides flexibility. This thread is not concerned with Quad '34s.

If what you say is correct there would have been thousands of damaged Quad electrostatics when used with ‘44s. The low frequency rollof engineered into Quad preamps by Quad was deliberate in order to avoid arcing in Quad electrostatic speakers.

Years ago John Atkinson measured an ESL 63 in a large American living room with the panels near the side walls to maximise bass response. He found (from memory) that it started rolling off at circa 70Hz and was very significantly down in dB by 40Hz. After Quad finally recommended using a subwoofer with these panels (the bass-light Gradient subwoofer) there was an immediate improvement, as I hear it. This with a hugely inadequate subwoofer. Before finally accepting that an H2 is not bass light why not try a good subwoofer with it?

I can’t remember what John atkinson found re: high frequency extension but it cannot have been impressive. That bit is for those who are most impressed by measurements. Me? I prefer to consider at measurements but then, like so many engineers have said, to let the ears be the final arbiter.
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Quad 44/34 pre amps were definitely not rolled-off in order to avoid arcing electrostatics. Even if they were, the reduction at 20Hz is tiny and of no consequence in this regard. I don't know where you found this information but your comment makes no sense whatsoever and was (is) most certainly not Quad's view.

The 44 & 34 share topology and basic specification, plus internal components. If you are going to discuss modifying one then it naturally applies to the other.

On frequency response, I'm more than happy to post my own measurements of Quad electrostatics driven by a Quad pre amp - clearly flat to 20kHz, and a bit further still in fact.

On the H2, Martin and I have both measured these with strong output to 30Hz in room.
 
Re: Quad intentionally designed preamps with limited low frequency extension (see review by CHRIS BEECHING, Hi Fi News, Dec. 1994). Although the ’22 and not the ’44 is specifically referred to, I understand that Quad continued this practice for later models for the same reason, to protect against arcing.

Re: the ESL ’63: “…the low end extends to ‘just below 40Hz’…”, J. Gordon Holt, Stereophile, Sept. 23, 1983 (see, also, follow up in Nov 83 issue “…our first two samples broke down and started arcing, protection circuit or not…”)

Has anyone measured the bandwith of an early ’44 (NOT a modified one, nor a later model, and NOT a ‘34)? Can they give the LF extension (not just the -3dB point ) and also the HF extension? If so, please specify which CMOS electronic switch(es) with which module(es) were in use during measuring..
 
eguth said:
Re: Quad intentionally designed preamps with limited low frequency extension (see review by CHRIS BEECHING, Hi Fi News, Dec. 1994). Although the ’22 and not the ’44 is specifically referred to, I understand that Quad continued this practice for later models for the same reason, to protect against arcing.

Re: the ESL ’63: “…the low end extends to ‘just below 40Hz’…”, J. Gordon Holt, Stereophile, Sept. 23, 1983 (see, also, follow up in Nov 83 issue “…our first two samples broke down and started arcing, protection circuit or not…”)

Has anyone measured the bandwith of an early ’44 (NOT a modified one, nor a later model, and NOT a ‘34)? Can they give the LF extension (not just the -3dB point ) and also the HF extension? If so, please specify which CMOS electronic switch(es) with which module(es) were in use during measuring..
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The arcing is due to excessive voltage on the plates, not the LF bandwidth of the pre. I'm not sure why you have highlighted the LF point of the 63s - is this in question?

If the CMOS switches worry you, just replace them with modern versions which are technically a bit better. So long as you don't exceed the rail voltage of the 4066 there is no downside.

On the specs, I doubt very much we'll find anyone with an old original 44 to test but i have the Martin Colloms review of the 44 written within the first year of release in HFN/RR. This was a review of the 44+405 and the measurements have both in circuit, so please note that figures for the 44 alone will be better as these include the power amplifier:

This gives -0.2dB at 20Hz and -0.5dB at 20kHz.

Outside the audible range we have:

Sharp LF roll-off giving -18dB at 10Hz.
Gradual HF roll-off giving -5dB at 45kHz

Distortion at 1w via aux input is given as 0.013 (20Hz), 0.003 (1kHz), 0.04 (20kHz).

Those look impressive to me given they are taken after the 405 power amplifier which of course also has some filtering outside 20-20k.
The distortion figure at 20kHz is particularly interesting as not only is it low but likely dominated by the 405 power amp. I can see no evidence to panic wrt the 4066 devices from these figures.
 
I haven't seen the Colloms review, and you do not give a reference. I can't locate it online.

You say:
“…I can see no evidence to panic wrt the 4066 devices from these figures…”

Agreed, but this just shows how misleading measurements can be.

Indeed the figures are fine. But why are there such large discrepancies between these and measurements made by others? (Your own measurements point to the ’34 being an improved preamp in some respect).

However, whatever the measurements prove they do not disprove what I heard and Les Westenholme has maintained, namely that the sound of the original is (as I put it) “mediocre” and, as he puts it, really only fit for use in lifts. I think we can all be big enough to give Les a bit of leeway with hyperbole; it makes things clearer and more fun upon occassion.

I can’t speak for Les, but I think he must have sound reasons for identifying the culprit as the 4066s. And I have no doubt that without them- or even modern 4066s- the sound of the ‘44 would be significantly improved.

Christian Steingruber has this to say:

“…Unfortunately the sonic performance of the 44 was flawed, because the same mediocre Op-Amp (TL071) as in the 405 was used. In addition these sensible Op Amps were powered by an unregulated DC line. The result was a rather shut-in sound quality. Some specialists like Avondale Audio have exchanged that Op Amp against modern types and fitted separate voltage regulators, which bettered the noise performance and the sound dramatically.. .”
 
MEMOIRS OF A DIY HI FI NUT - Part XVIX​
QUAD 44 PREAMP: UPGRADES​

II

JUMP IN​

A Slight Digression

As a result of my involvement with the quixotic (now long- defunct) journal ‘Audio Conversions’ (AC) I learned a lot and my system was dramatically improved.

AC set forth some splendid ideas and DIY articles, not all of them technical. There is no journal like it now.

I will to pass on to you some of the best of these ideas for upgrades. Intriguingly, a few can be carried out for almost nothing- others at less than horrendous expense.

Pay close and careful attention to star grounding.

Use separate power supplies at every stage of every piece of equipment if you want the best performance.

Huge transformers can bring huge sonic benefits.

There is no piece of commercial equipment that cannot be upgraded or improved through the use of better components or circuits.

These are some- not all- of the best ideas that were published in AC. They have stood me in good stead over the years. Not surprisingly, I applied them to the ’44.

My general aims in writing about Hi Fi have not changed since I conceived of and started the London Live DIY Hi Fi Circle in 1989.

“…No.1…to attract and assist very poor people (also rich ones) to achieve audiophile standards on a very limited (or almost non- existent) budget. “
Well, that is my primary aim and I will leave it at that for now, with the comment that some who should know better settle for less, though this is not necessary on a budget..."

End Of Digression

Next: onwards & upwards
________________________________________________
 
I now refer to a review of the ‘44/405 that appeared in the January 1980 issue of Hi Fi News. I don’t know whether this is the first published review but since the ’44 came out in 1979 and the reviewer refers to the “long awaited 44” it seems likely that this is a review of the original ’44.

On p.137 (2nd column) it says:

“…the 44 showed a tendency to slight lift on the mid treble, this highlighted by an early rollof at lower frequencies… As a whole the amplifier system also demonstrated a slightly premature rollof at the highest frequencies…”

“…the more limited than usual disk bandwidth demonstrated by the 44 was subjectively apparent…”

This, of course, neither reveals extremely limited bandwith nor that the CMOS electronic switches are related to bandwith limitation nor explains the poor sonic performance that some (including myself) hear.

I am beginning to wonder what the effect of listening through 15 of Les W’s daisy- chained reed relay selectors would be on the sound.
 
eguth said:
Indeed the figures are fine. But why are there such large discrepancies between these and measurements made by others? (Your own measurements point to the ’34 being an improved preamp in some respect).

However, whatever the measurements prove they do not disprove what I heard and Les Westenholme has maintained, namely that the sound of the original is (as I put it) “mediocre” and, as he puts it, really only fit for use in lifts. I think we can all be big enough to give Les a bit of leeway with hyperbole; it makes things clearer and more fun upon occassion.
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The discrepancies arise because if measuring a 4066 it must be under the same conditions as found in the Quad circuit. These devices perform far better in high impedance circuits, at low current and on max voltage rails. The Quads provide these conditions.

Sorry but when someone describes the *work of Walker, Baxandall and Albinson as 'fit for use in lifts' I'm not letting it pass without comment.

If you want real hard evidence that these switches, in this circuit, do not 'strangle' the music I can provide it - so long as you can download and replay wav files. Same goes for anyone else interested.


*All had input into the 44.
 
As an aside, regardless of all this talk of measurements and such, I've heard a Quad 34/405 some years ago and was very impressed. Very impressed. It was the trigger that got me into what I learned was a "proper hifi shop" rather than a chain like Comet, back when Comet was a warehouse.

The 34/405 didn't sound anything like lift (elevator) music, or whatever was mentioned earlier. I can only imagine anyone thinking that has a preference for music to pin them back in the chair and slap them around a bit. Or a lot. This is ok. We all hear things differently and we all want different things from what we hear.
 
It is a mistake to assume that the sound of a '34 is the same as a '44- especially if the '44 in question is an early production one.

Apparently, Quad began an improvement programme for the ’44 shortly after it went into production.

According to H. Popeck, the ’44 was progressively upgraded. In his opinion it was at first slow, sluggish and boring- with an inoffensive and only adequate midrange.

Later in the production run Quad told Popeck that the Mother Board had been totally redesigned.*


* Quad 44- all you want to know, Popeck, H., Vintage Audio Review, 15 Sept. 2010
 
In my experience, Mr Popeck was bang on with his assessment of the 44 and although Quad, using a large quota of wishful thinking, merely revised the motherboard in detail only....the circuit and component idents remained much as before.

It is worth noting that the maxim 'distance lends enchantment' applies here, so we begin to see dribbles of sentimentality creeping into this thread. I have yet to learn of one reviewer who habitually used Quad gear as a reference point in his main system. Says a lot really.

Having said, many thousands of listeners enjoy their Quad gear for year after year and who am I to argue.
 
Radfordman said:
I suppose that I'm unlucky, bought the 44 when it first came out. However, it's still working!
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It will be fine.
They reworked the phono card early on as the LF roll-off was a bit premature (arguably remained so).
As the amp is card based, you can just buy a later card. You can also use a CD card.
 
I'm no reviewer but I very much enjoyed my 44-405 when I used it and I syill have a 405 as a backup amp. If times were hard I'd happily go back to it. I also remember going to see a friend with the full house LP12/Armag/Aro/Clavis/52/135/DBL system, then coming home to my LP12/Notts/1042/Quad44-405/Keilidhs at about 1/10 what my friend had spent and being VERY happy with my choices.

I listened to a 44-405 against a variety of new upmarket integrateds in the late 90s - Audiolab, Exposure, etc in the £500-1000 range, and the Quad never had any of them come close overall.
 
Greetings to All.
Happened to look at this thread as I've got one on the bench for repair.
Anybody going to Tonbridge on Sunday?
Regards
Henry
 
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