Quad amplifier secret recipe

[Oldpinkman]

OK - since you are all such lovely chaps, following recent banter with Gordon and Dave, and as hinted at previously, here is my secret No1 top Quad 303/405 power amp upgrade tip. My own 405-2 has a reworked bridge, burr brown op-amps, electrolytic that appears not to be in the signal path, but is, taken out, input gain lowered, and a few other gizz's, but my favourite mod I have hinted at before is

Hard wire the signal cable spade terminals. Cost - about 3p

My friend Owen, would disagree, having moaned at me for doing this when he came to service my amp, and pointing out the correct solution, as he had planned, and I believe now done, is to fit gold plated spades in place of the existing jobs. He also asked "what the f*** did I solder the mains spades for"? given that there are so many switches and fuses on that supply anyway, and the amp only sees current from the reservoir capacitors etc etc. I put it down to boyish enthusiasm - Arthur, rather unkindly I feel, to the suggestion I wouldn't know a signal cable from a mains cable anyway. Very unnecessary comment.

What people think they are doing surface mounting op-amps when they leave those ghastly corroded spade terminal untouched is a mystery to me.

Take it or leave it :)

[Firebottle]

I'll take it my man, I haven't had the top off my 'home brew' 405-2 since I recapped and upgraded the opamps (big improvement), but I think the signal wires are still on spades :scratch:

:cool:Alan

[Oldpinkman]

I'll take it my man, I haven't had the top off my 'home brew' 405-2 since I recapped and upgraded the opamps (big improvement), but I think the signal wires are still on spades :scratch:

:cool:Alan

Cool - let me know what you think :)

[Ammonite Audio]

What people think they are doing surface mounting op-amps when they leave those ghastly corroded spade terminal untouched is a mystery to me.

Take it or leave it :)

Soldered joints must be better than crimped spades, surely? Well. IME things are not so simple and spades can in fact be perfectly fine, as they are in my Lyngdorf TDA2200 (power cables and speaker connections). Depends entirely on how they are done, of course.

[Firebottle]

They say the threads are no good without pictures so here you are folks, the inards:

http://i601.photobucket.com/albums/tt97/Paramotorpilot/405-2.jpg

:cool:Alan

[Oldpinkman]

Interesting pic Alan. Did the original transformer fail, or did you particularly want a toroidal?

[Oldpinkman]

Soldered joints must be better than crimped spades, surely? Well. IME things are not so simple and spades can in fact be perfectly fine, as they are in my Lyngdorf TDA2200 (power cables and speaker connections). Depends entirely on how they are done, of course.

You'll note mine is probably coming back with "quality" crimps. But as with so many Quad things, the quality design was let down by cooking quality implementation, and the standard spades are greatly improved with hardwiring. Made a worthwile difference every time we did it , but like I said - take it or leave it. :)

[Oldpinkman]

Soldered joints must be better than crimped spades, surely? Well. IME things are not so simple and spades can in fact be perfectly fine, as they are in my Lyngdorf TDA2200 (power cables and speaker connections). Depends entirely on how they are done, of course.

Sorry, just to clarify. You've tried your Lyngdorf TDA2200 with both crimps and soldered joints, and prefer the crimps? Or can't hear a difference between solder and crimps, so reverted to crimps for the convenience?

[DSJR]

Solder should ONLY be used to seal and anchor a proper MECHANICAL connection. The Quad spades are VERY tight fitting, so shouldn't ever really give problems unless messed with by subsequent owners IMO... All of Naim's power amps still use crimped push-on connectors IIRC and these never usually give problems over the years, unlike the under-rated caps which bulge and leak on old-uns....

I remember Malcolm Steward being ridiculed (he's well used to that, the plonker that he is in HiFi matters) for moaning about moulded IEC leads with crimped internal connections. Crimping made sense to me since there's a very tight mechanical connection and the moulded outer makes a good air-seal I believe.

[Oldpinkman]

Solder should ONLY be used to seal and anchor a proper MECHANICAL connection. The Quad spades are VERY tight fitting, so shouldn't ever really give problems unless messed with by subsequent owners IMO... All of Naim's power amps still use crimped push-on connectors IIRC and these never usually give problems over the years, unlike the under-rated caps which bulge and leak on old-uns....

I remember Malcolm Steward being ridiculed (he's well used to that, the plonker that he is in HiFi matters) for moaning about moulded IEC leads with crimped internal connections. Crimping made sense to me since there's a very tight mechanical connection and the moulded outer makes a good air-seal I believe.

So why surface mount an opamp, or fit a gold-plated socket, rather than a standard socket on a PCB?

[sq225917]

smt components are easier to fabricate with pick and place robots, and cheaper.

Why use a gold plated socket? Because it doesn't tarnish and for no other reason.

[Firebottle]

Interesting pic Alan. Did the original transformer fail, or did you particularly want a toroidal?

The 405 boards were bought from an 'after market' source, I think they were destined for an active speaker, they are not fitted with the protection modules, but the manufacturer went bust. This is a long time ago, the two boards cost me £30 then the rest was cobbled together. The reservoir caps have been replaced since it was made and as I said the pcbs have been re-capped etc.

All good fun,
Alan

[Ammonite Audio]

Sorry, just to clarify. You've tried your Lyngdorf TDA2200 with both crimps and soldered joints, and prefer the crimps? Or can't hear a difference between solder and crimps, so reverted to crimps for the convenience?

No, I have not interfered with it, but that amp has seen off every single pretender to its place in my house, so I am happy to conclude that Lyngdorf know how to execute crimped spade terminations properly.

[Oldpinkman]

I'll pop back and let everyone know it doesn't work then. Anybody got any cotton buds spare? :ner:

[Oldpinkman]

I love this place. If I ever run a hifi company again I shall employ a few of you for sure. It would save all that fannying around testing and auditioning if we "just knew" it would be better or ok. So crimps in the signal path don't matter, but a different mains cable, taking mains that has travelled half way round the country, a substation, your consumer unit, the hall, landing and living room in the walls, a switched wall socket, a fuse in the moulded plug , then needs a designer kettle lead to get it "properly" a whole metre to the input socket of your laskeys kit, where it doubtless meets a few more fuses and switches before reaching a transformer.

Standard crimps corrode with time. Solder makes the joint area bigger by adding conductivity to the outer surfaces of the joint as well as the contact surfaces of the crimp. Cheez - there are threads on the different sound qualities of different solders - a but too directional cable for this boy. Don't kid yourself that corrosion is just on the outside of the joint, not the oxygen free air-tight contact surfaces. Last weekend i removed the failed (years ago I guess) backup 12v sealed lead acid battery from our new 2nd hand caravan alarm. The crimps were corroded. The black one so badly it conducted no current. A soldered joint wouldn't have stopped the battery leaking, but it would conduct current same as day 1.
Anybody have any snake oil available at member only prices?

My earlier reference to "surface mount" was sloppy english. Net audio and others upgrade quad 405 boards by changing the opamps. As a recommended super duper optional upgrade, instead of fitting the opamp in a gold plated pcb socket they will solder the ic pins direct to the pcb. Why even think of doing that? My answer is above.

:doh: Richard

[StanleyB]

I love this place. If I ever run a hifi company again I shall employ a few of you for sure.
Well there are quite a few members here with a proven track record in the design and manufacturing industry. Some of us even enjoy a worldwide reputation for our electronic skills. I myself invented quite a few products or electrical/electronic circuits that have made quite a few people stinking rich after they ripped me off. It's one of the reasons why I decided to set up my own business instead of getting locked into disputes as to whether the company I worked for or me who owned the rights to an idea.
But I digress.

As for the debate of crimped versus soldered connection: You are plain wrong. In fact dangerously so.
A crimped connector will still continue to work long after a soldered connection passing the same amount of current and voltage has failed. When solder heats up and cools down it will start getting brittle and eventually separate into two sections. Each section will cling on to one end of the connection point.

When you are talking batteries, you are talking about very high currents. A sealed lead acid battery for an alarm is likely to be at least 1AH. At 12V that would be equivalent to 12Watts. A 12Watts soldering iron would melt a soldered connection given enough time.
This is one of the reason why you'll find crimped connections being used in high current appliances such as kettles, toasters, timers in washing machines, etc. Solder would melt and cause a fire hazard. I remember with sadness the dismissal of a good friend of mine when I worked for the repair department in the now defunct Comet stores group. He was a field repair engineer and had broken the spade on a crimped connection point, so decided to solder the two ends of the remainder of the connectors together since he did not fancy driving all the way back to the workshop to get a new spade. The solder melted over time and an arcing point started to develop across the two intermittent ends. A fire ensued that raised the property to the ground. Luckily nobody got killed, but the liability bill was more than twenty times his yearly salary.

Whilst I also have my doubts with regards to some items offered for sale as solutions to some audio performance bottlenecks, it is not all snake oil. Just look at my thread about the new Bushmaster. I have just completed the design of a circuit that can turn a noisy switched mode power supply rail into one that is just as clean or even cleaner than a linear power supply. No doubt many engineers have been working on such a solution for years and eventually gave up with the words "It's impossible to solve". And no doubt many engineers and companies around the world are going to buy my new DAC just to rip it apart and see how I did it so that they can then copy it into their own designs. But equally, there will be many who would be thinking that it is all snake oil. Which is why I posted actual screenshots of my measurements, instead of relying on golden ears to confirm the existence of a solution to a big problem.

I worked on the design of electrical accessories as well, such as switches and leads. Next time you run into an old mains switch or socket marked PMS or Philex, it might well be one of my designs or that of my now deceased friend Russell Shore. Between us we had to know just about everything with regards to noise, high currents, etc. across two mains connection point. Many of those things are part of the EMC and BSI testing of those kind of accessories, but are not required by law to be included in a specification sheet with the item when it is sold. But they do make a difference to the performance of the items in many applications.

So a bit less scepticism would go a long way. They laughed at Dyson and Barnes Wallis. But who is laughing now? Consider that, before you condemn the experience and knowledge that is freely expressed by some quite technically capable members on AoS.

[Barry]

This might be of some interest: http://theartofsound.net/forum/showthread.php?9776-Soldered-and-crimped-connections-the-pros-and-cons

[Oldpinkman]

Hi Stanley

Owen has a switched power supply on the hybrid class H amp he has signed off the design for in a professional audio contract... I think its his third implementation, although we originally discussed the idea more than 20 years ago. And last time I checked he knew how to measure current

I am prepared to put my finger on the joint of the low current alarm backup battery and will let you know if 3rd degree burns result

Like a complete tit -as previously discussed - I soldered the mains crimps on the Quad too. There is no evidence they have behaved in the way you describe.

Regarding mains leads - I don't understand how they might work, and in spite of repeated comments to that effect, nobody has attempted an explanation for me (I appreciate, as do Owen, Arthur and John Westlake, that it is a thankless task trying to explain complicated subjects like that to an accountant like me, but they have a pop at it)

And even in the absence of any attempt to explain the science behind it, I haven't dismissed the possibility it might work. But again, I set a simple enough challenge, with Blue Peter level technology, and asked the faithful to try it and report back. None have confirmed they have accepted the challenge. Of course, they may be quietly plugging away at it in the background ready to report back after the 30 days is finished, but I would have thought on a forum - which exists to have something to say and something to read - you might have said "ok - I'll try it for you". I'd buy a posh lead and try it myself, but if my conclusion was it didn't work, that would only establish I am deaf, or we have the wrong sort of electricity in Kent.

I think scepticism is very healthy. I accept that sarcasm as an attempt at humour might be wearisome, but I don't like to take myself too seriously

Can we stay friends please? :)

[StanleyB]

Richard, I shall let you carry on spreading your own gospel. I had to endure such small talk for years across numerous tables in equally numerous meetings. After explaining things in fine details so that the sceptics could be convinced, and then watch some of them become millionaires afterwards, I have no intention of making that mistake again. Especially not on a forum that is so widely read across continents.

[Oldpinkman]

OK Stanley

I understand. I'll read your Bushmaster thread (which I haven't because dac's were off my radar). Having watched Walker and Systemdeck go "sort of" acrylic shortly after the PT launched, seen rip-off achromats on ebay (Arthur is defending his patent a bit more rigourously this time), take a look at the current Gyrodec, which is an open skeleton pink triangle (acrylic platter, inverted bearing, DC motor, suspended not floating suspension...) I understand how you feel. But I wasn't asking for detailed secrets - any clue would do.

Like arm effective mass and the childrens seesaw analogy I used. (Incidentally - I chatted with AK about the brilliance of the Dynavector arm having a low effective mass on the satellite arm but all the rigidity from the main beam. He pointed out, quite gently, that the low effective mass was only in the vertical plane, and it was bloody enormous in the horizontal plane. :doh: See - I get things wrong, and my friends try to explain in language I can understand why I get them wrong.)

I like to understand things - preferably either in a way that is apparant, or that I can test, and I am happy to accept that I will get them wrong. On here, I try to only pass on advice from people I trust (the soldering was a Westlake idea - Jones is somewhat more sceptical - although less outright dismissive than you. It's not an easy thing to A:B reverse. Maybe just cleaning the terminals made a difference. I'd be interested to hear Alan's comments, although his home-brew 405 looked a lot shinier than the regular ones, so maybe there will be less effect. Are you telling me solder doesn't conduct current? The spades on the quad are a pretty dull grey quite quickly suggesting corrosion. And of course - soldering crimps allows the solder both to conduct across the non-contact points, and protect the crimp, without in anyway undermining any inherent ability the crimp itself has. The only costs are 3p for solder, and some inconvenience when you come to service it. Like I said -take it or leave it. But if soldering signal leads is as fundamentally flawed as you appear to imply, then why don't we crimp the rest of the PCB?

another example - AK explaining to me why the subchassis on a PT has a variable weight armboard, to place the centre of mass at the centre of suspension. "Imagine a weight on a coil spring held in your hand. Gravity will constantly be trying to destabilise the system. Any disturbance to the system and gravity will cause the weight to topple over (A "floating" system"). Now, turn it upside down so the weight hangs from the spring. Now every time the system is disturbed - if the spring is in the centre of the weight, so the effective mass of the weight is at the centre of the spring, the system will naturally correct itself and return to rest. If the weight is not in the centre, but on one side of the spring, the system will lean to that side and need some other force to correct it (the arm cable to guy down the subchassis on an LP12)" . I can visualise that. I can see how it works

Could someone do me that sort of explanation for how a mains cable could have ANY effect on how a piece of audio equipment sounds? I asked my mate Owen- who hasn't tested this - and is inclined to have this response to anything even slightly snake oil - and his response was "utter tosh". I need another friend to give me a better explanation I can challenge him with. Or someone to carry out a credible blind listening test over a 30 day period.

Mind - I noticed a single interconnect down at Arthurs factory when I was down there, of a diameter which could have repaired a strainer on the Clifton Suspension bridge, with a bloody great arrow on it. So of course I took the piss mercilessly. And being Arthur he did his usual flustered angry shout-down. He had a pop at bullshit, and I said "I'll check with Owen" , and he sulked even more. I'm not sure I can remember it verbatim, but the gist of it, as I understood it, was "a boy has to make a living, and there's a market out there" :)

[Ali Tait]

In regard to using crimped connections on low voltage and current connections, I have seen corrosion set in over long periods of time, such as in connections in old high voltage switchgear at work, on the auxiliary connections that run to the protection relays for instance, sometimes to the point that no current flows, so I agree with what Owen says, though I also agree with what Stan says regarding high current connections, as I have also seen that happen at work.

For low voltage connections, we used to use a product called Darathene, a contact enhancer that worked very well, but doesn't command the foo prices of deoxit and similar. Needless to say, I kept a couple of cans of the stuff for my own use, which should last me a lifetime. It bloody works too!

[Oldpinkman]

This might be of some interest: http://theartofsound.net/forum/showthread.php?9776-Soldered-and-crimped-connections-the-pros-and-cons

Thanks Barry. Really interesting. I raced through it - but will do it proper justice when I am on hols. This may account for why the conclusion appeared to come out of thin air with regard to soldering a crimped joint. I can't find the bit which explains why it might undermine it.

Not my experience with the Quads (we didn't unsolder them again, and redo it repeatedly to test but we did a handful one at a time, and were pretty convinced - 20 years ago). Mind they're not the prettiest example of the crimpers art on the Quad

[Oldpinkman]

They laughed at Dyson and Barnes Wallis. But who is laughing now? Consider that, before you condemn the experience and knowledge that is freely expressed by some quite technically capable members on AoS.

As I recall Barnes Wallis didn't say "trust me - it will bounce - just send a few hundred air crew over and give it a go". He produced lots of sums, and drawings, and fired marbles at goldfish to prove it first :)

[DSJR]

So why surface mount an opamp, or fit a gold-plated socket, rather than a standard socket on a PCB?

Three of my power amps have IC sockets (non gold plated) for the fitted IC's. Two of these amps (in bridged form) were run up to fifteen hours a day for nigh on thirty years with no ill effects at all, but the amp from a suspect source (bought second hand years ago when I was on the road) gave trouble, the socket needing a good clean up after years not being used and put in a damp? environment. It's now ok and doing fine for heaphone use...

Like I said, the things that usually gave trouble on 405 Quads is leaking supply caps after twelve years or so and the typical studio or domestic environment is 'unlikely' to cause failure of the crimped connectors unless they are disturbed and a possibly corroded part is then the point of contact - in my opinion obviously.

[Oldpinkman]

Oh Gosh Dave, I am beginning to feel this all gets too involved. NetAudio (as I mentioned earlier) supply various opamp upgrade alternatives and one of their options is to direct solder the opamps instead of socketing them. That was the reference to IC's and sockets. My pip has a (gold plated) socket for the header which sets the input loading. Draw your own conclusions as to my (my friends) feelings on sockets.

Hard-wiring the spades impressed us enough to do it again, and again 20 years ago. I speculated a reason why it might have worked. I didn't suggest they failed - at all. The failure of the crimp on my caravan, was just evidence that corrosion can spread into the joint. Mild corrossion might, I speculated, be the reason that soldering appeared to us to improve the sound of the 405 when we tried it. I also speculated that a larger surface area for the soldered joint might account for it. What is a fact, is that all the spades on mine have been soldered for many years, we all of us thought we liked the difference at the time, and Owens offensive comments about my soldering were all to do with the time it took him to unsolder them, or the pointlessness of soldering mains supply, and not the other issues, raised by some on this thread.

It's more than the reservoirs that go on the Quads. Most people who recap the Quad recap the lot - which we've just done on mine. The hum on mine was C5 - one of which had no measurable capacitance at all. The reservoirs actually measured ok on mine, but we replaced them anyway. Interestingly one board was 10db worse than the other.

[synsei]

I replaced my standard mains cables with shielded cables (Belden 19634) and the improvement was tangible, resulting in a lower noise floor which consequently brought forward further subtle detail in the music compared with using the standard cables. I'm not sure I could justify spending more on mains cables than I already have as I don't think my systems resolving powers would benefit from it, I could be wrong there however. As for solder vs crimps, I can see both sides of the argument however I'm not going to let it worry me. Taking into consideration that we live in 'Green' times, even so, I leave my equipment on 24/7 because as Stanley mentioned, solder joints can be susceptible to heat cycle fractures (is that the right term Stan?). I have seen this for myself incidentally.

[Oldpinkman]

I replaced my standard mains cables with shielded cables (Belden 19634) and the improvement was tangible, resulting in a lower noise floor which consequently brought forward further subtle detail in the music compared with using the standard cables. I'm not sure I could justify spending more on mains cables than I already have as I don't think my systems resolving powers would benefit from it, I could be wrong there however. As for solder vs crimps, I can see both sides of the argument however I'm not going to let it worry me. Taking into consideration that we live in 'Green' times, even so, I leave my equipment on 24/7 because as Stanley mentioned, solder joints can be susceptible to heat cycle fractures (is that the right term Stan?). I have seen this for myself incidentally.

I'm not quite sure where to go with this. It's not that I think you're wrong, it's that I don't understand how a mains cable might make a difference. Nobody has yet offered an explanation.

Nor has anyone offered to do my 30 day trial - which, whilst it's a bit of a cheek of me to ask - and might sound a bit confrontational, is not hard to do in the cause of "objectivity". I would try a mains cable for myself, but if I hear no difference, the possibilities include

1) My hearing is not good enough - or I am missing something
2) The electricity here in Kent is different (believe me I've heard similar claims for supporting "faith" before)
3) I muck it up with other aspects of my system. For example both my various 2 channel components and my various AV components currently plug into multi-way sockets with spike protection and a "sleep function" (when socket 1 powers up - all power up). It is into that box that I would plug a designer mains cable if I try one. Does that invalidate the trial? Because my cable from equipment to wall socket will be 2 cables with another plug and socket involved. I have one spare wall socket I could use for the trial. I could try hearing whether my existing cables sound better from the wall direct or the multiway (I can hear no difference at all). Does everyone using special mains cable plug straight to the wall socket? Does it need a particular type of wall socket? Are there designer multi-way sockets you have to also use with the designer mains cable? Do the fuses or RCB's on the distribution board affect it?

Because I have no concept of what it is supposed to do, I have no idea of how to make sure I do it properly. And I never get an objective answer to these questions. Just "Believe me - it works".

I don't understand. My brother in law is a church minister in Devon for a minor church. He can discuss at great length the bible and his "reasoning" for accepting his faith - but it comes down to "you have to believe". That hasn't applied yet in my experience in HiFi. Help somebody please :scratch:

So I am not able to produce the effect for myself. Nobody has even attempted an explanation. Nobody will back their claims for improvement with a simple test. I could walk into the living room tomorrow and tell you whether it is the F5 or Fx3 on the deck blindfolded. I could come back from holiday and tell you whether it is the Quad or the Arcam. I don't need to sit and endlessly compare one with the other. There are things sound different, and they matter when you are listening. If mains cables make a difference, I would expect near to 90% plus correlation of the results to the random numbers. ie at least 90% of the time, if A is playing, A is what I would write down. I am saying I would get 100% right on a blind A:B like this with F5 and Fx3. (Before you try to call my bluff, setting up an arm and cartridge is beyond Sue, and far more variable than plugging in different mains leads)

Any non-hostile constructive responses most welcome.

On the subject of Stan and his joints, as an observation, and not a technical challenge, Owen turns all his kit off all the time, and honestly - he's a bright lad, knows electronics, and likes music. I don't believe he routinely resolders the joints. If I ever bring a Pip to a bake-off - the warm up time for a solid state device is as long as it takes me to remove my finger from the switch. I did, in awe of the Integral leave everything on for a few days, but cannot in all honesty say I noticed any difference when I started turning them off again. Different for valves of course. And hard to be sure. You can't flit between a warm amp and a cold one easily. So it is easy to believe in such things and hard to challenge. Although if it were a truly significant difference I could do my "walk into the room" test like with the F5 or FX3

[DSJR]

Richard, please don't fret (I'm sure you're not :))

Net Audio have had a few goes with the 405-2 boards and so have Dada (I'm a Dada man myself and rate them highly for value for money updates - duh-duh :lol:)
My 405's were but a third of their current age when I had them (one in the late 80's and t'other in early 90's) and back then they'd both had Quad issue 7 mk2 boards newly fitted and supply caps replaced with modern but same value alternatives, so nothing like the update you've done. I believe Quad themselves can still supply new mk2 boards for the 405, now issue 10 IIRC, but I have no idea how these stack up. No offence to net Audio, but I read a disturbing comment about their 303 supply board, the original being designed the way it was (by Peter? Baxendall) I believe, for a very definite reason and the modern 'revised' Net-Audio type not rated as highly. I refer to posts in the last year on the Yahoo Quad site. The 303 I've enjoyed had been totally rebuilt with all new components (caps and resistors/presets), but all boards were original and with soldered wiring as original ;) The 33 was bodged by me and although better than 'stock' in terms of bass depth and lack of overload, it's not as good as a modern device - the net Audio '33' is a different modern preamp using the same case and chassis..

I like the 405-2 very much, understanding it's main purpose in life was for Quad's own speakers and probably the other BBC-Legacy alternatives at the time. The fact that it doesn't like 4 ohm loads much and gets very hot and bothered when pushed hard is irrelevant to me now :)

[Oldpinkman]

Dave
Nah - I'm not fretting - well about towing a 2 tonne monster to the South of France maybe, but not this. For the record, and I'm sure you realise this, my mods to the 405-2 are Jones specials, not Net Audio mods. I was only pointing out way back, that Net Audio feel a benefit on getting solder on their opamps in place of sockets, when the signal passes through crimps. Since they rewire with posh wire, and get rid of the bloody ridiculous "wrap the signal leads in mains cable" loom that Quad use, they may well use better crimps too. The only NetAudio mod I was considering was the dual mono power supply, or a home-brew, but OJ is skeptical (not outright dismissive - but he's usually right). One he says the transformer windings whilst separate use a common core, and that will possibly result in interference between the 2, and 2 he argues that all the current should be being supplied by the reservoirs, so any effect in the transformer wouldn't matter. If I want to do it properly fit 2 transformers - which effectively takes me down the monoblock route, and, well - he's going to mend the Integral instead, so who cares? :)

They make a good amp for sure - in spite of all those soldered joints on the boards! :)

[Oldpinkman]

Well there are quite a few members here with a proven track record in the design and manufacturing industry. Some of us even enjoy a worldwide reputation for our electronic skills. I myself invented quite a few products or electrical/electronic circuits that have made quite a few people stinking rich after they ripped me off. It's one of the reasons why I decided to set up my own business instead of getting locked into disputes as to whether the company I worked for or me who owned the rights to an idea.
But I digress.

As for the debate of crimped versus soldered connection: You are plain wrong. In fact dangerously so.
A crimped connector will still continue to work long after a soldered connection passing the same amount of current and voltage has failed. When solder heats up and cools down it will start getting brittle and eventually separate into two sections. Each section will cling on to one end of the connection point.

When you are talking batteries, you are talking about very high currents. A sealed lead acid battery for an alarm is likely to be at least 1AH. At 12V that would be equivalent to 12Watts. A 12Watts soldering iron would melt a soldered connection given enough time.
This is one of the reason why you'll find crimped connections being used in high current appliances such as kettles, toasters, timers in washing machines, etc. Solder would melt and cause a fire hazard. I remember with sadness the dismissal of a good friend of mine when I worked for the repair department in the now defunct Comet stores group. He was a field repair engineer and had broken the spade on a crimped connection point, so decided to solder the two ends of the remainder of the connectors together since he did not fancy driving all the way back to the workshop to get a new spade. The solder melted over time and an arcing point started to develop across the two intermittent ends. A fire ensued that raised the property to the ground. Luckily nobody got killed, but the liability bill was more than twenty times his yearly salary.

Whilst I also have my doubts with regards to some items offered for sale as solutions to some audio performance bottlenecks, it is not all snake oil. Just look at my thread about the new Bushmaster. I have just completed the design of a circuit that can turn a noisy switched mode power supply rail into one that is just as clean or even cleaner than a linear power supply. No doubt many engineers have been working on such a solution for years and eventually gave up with the words "It's impossible to solve". And no doubt many engineers and companies around the world are going to buy my new DAC just to rip it apart and see how I did it so that they can then copy it into their own designs. But equally, there will be many who would be thinking that it is all snake oil. Which is why I posted actual screenshots of my measurements, instead of relying on golden ears to confirm the existence of a solution to a big problem.

I worked on the design of electrical accessories as well, such as switches and leads. Next time you run into an old mains switch or socket marked PMS or Philex, it might well be one of my designs or that of my now deceased friend Russell Shore. Between us we had to know just about everything with regards to noise, high currents, etc. across two mains connection point. Many of those things are part of the EMC and BSI testing of those kind of accessories, but are not required by law to be included in a specification sheet with the item when it is sold. But they do make a difference to the performance of the items in many applications.

So a bit less scepticism would go a long way. They laughed at Dyson and Barnes Wallis. But who is laughing now? Consider that, before you condemn the experience and knowledge that is freely expressed by some quite technically capable members on AoS.

I have read this carefully again. I have also read your Bushmaster thread carefully, and will comment on it after this comment, in case you miss this response. You know the saying "just because you're paranoid doesn't mean the bastards aren't out to get you". Unless I have really missed the point, and I invite you to correct me in a non-hostlie way if I have, this seems an inappropriate and paranoid comment. I would note, briefly, this thread was originally about sharing a suggestion John Westlake made to me after changing the opamps on my 405-2 to hardwire the spade terminals - on a take it or leave it basis. A few of us had the amp at the time, and all did the "mod" and all thought it improved it (to be honest, far more than the opamp upgrade in my case).

To keep this short, I think your Barnes Wallis / James Dyson reference at the bottom is with regard to mains cables and not solder and crimps. It was preceded by a statement of your design credentials for mains sockets and leads. I find the tone quite patronising and offensive. In contrast to your Bushmaster thread, which you draw my attention to - although I am struggling to see the relevance other than a marketing opportunity, where you offer some measurement evidence, for what appears to be a genuine , obviously beneficial, audio product, your comment on this thread appears irrational and defensive in a way I more usually associate with the snake oil brigade.

I have clearly stated I like to adopt a rational approach, but have no personal expertise (but have friends I trust, who do have that expertise, with whom I cross-reference any claims I want to understand). I like to understand what is around me. Preferably by at least a tangential grasp of the theory. But failing that by repeatable evidence which I can test and prove for myself. I have noted I don't understand how changing a mains lead can make a difference AT ALL, never mind some of the hyperbolic improvements claimed by some who post on this forum. I have noted I have been unable to observe the effect for myself. I have invited others to explain it, or carry out a convincing demonstration of the effect, with reasonable controls to remove psychological and subjective bias, that I could repeat, but nobody has. I have NOT (yet) dismissed it as bunkum. Indeed, as is the way with snake oil, I have troubled nights wondering whether I am missing out.

In that context, please explain "You condemn the experience and knowledge that is freely expressed by some quite technically capable members on AOS". Which technical knowledge have I condemned?

If you are making claim, as you appear to be, for the veracity of the benefit of a mains lead, please offer either a scientific explanation I can explore further, or experimental evidence akin to your noise trace photos on the Bushmaster thread.

Let's make this really simple. I have £200 burning a hole in my pocket. Which mains lead should I buy and how should I use it to definitely hear the benefits described?

I think your references to Dyson and Wallis are perhaps a touch vain and paranoid, rather than having any relevance to the thread on which they were posted.

James Dyson could not get vacuum cleaner manufacturers to see that there was a market for a bagless vacuum cleaner. This reflected primarily their concern for loss of revenue from accessory sales (branded vacuum cleaner bags) not a dismissal of the theory behind cyclonic separation. The Milk powder company I worked for 15 years ago, was pumping milk powder into silos with cyclonic separators in the late 40's - and they didn't invent them.

Barnes Wallis wanted to send over 150 airmen into heavy enemy flak to blow up 3 dams. More than a third lost their lives in the raid. He didn't just insist it would work - he provided detailed calculations for the various technological challenges, and backed them with carefully documented experiments to demonstrate they worked. Nobody was challenging his science. Very reasonably they were skeptical and asked if he was sure it would work, and he worried about that too - and carried out endless tests and improvements to improve the prospects of success. He didn't say "stop asking questions - I'm an expert and you are ignorant - if I say it works it must do"

I am not sure that the association of these two with the lack of science for mains leads is appropriate.

[Oldpinkman]

You won't believe this, but I can't help that. No need to make it up - others must have had similar experiences. Last time we used the caravan Sue reported the nearside brake light not working. So ahead of the big trip I went to change the bulb. Not the bulb - corrosion on the bulb and holder.

But none of the van lights were very good. Reason - corroded earth spade terminal. It's alright - I didn't solder them, just cleaned them with emery paper. Result - bright shiny lights :)

I wonder if that has anything to do with why my Quad 405 sounded better after I soldered the crimps? More likely it was fairy dust. Or - I know! Someone switched the kettle lead without me noticing! :doh:

[DSJR]

Not at all. The only shame is that you didn't have another amp with which to compare before and after to confirm your hearing. I love the 405-2, and one day would love to have another pass through my greasy paws (not good for clean contacts, greasy paws...). I need to get 'my' rebuilt 303 back first though :) And then an itchy desire for a DC300A and so it goes on :mental:

[Oldpinkman]

Not at all. The only shame is that you didn't have another amp with which to compare before and after to confirm your hearing. I love the 405-2, and one day would love to have another pass through my greasy paws (not good for clean contacts, greasy paws...). I need to get 'my' rebuilt 303 back first though :) And then an itchy desire for a DC300A and so it goes on :mental:

We did sort of. As I said we had at least 4 of them - we all used them in our own systems. But its 20, maybe 25 years ago, and it's a fuzzy memory. And I get a bit tired of being patronised with bullshit. I posted a helicopter post to make the point pictorially, but there are 3000 watts pass down the mains lead to an electric fire and they are cool to the touch even if the fire has been on for a week. So the joint is not going to get hot just because of the power across it. The idea of 12W through a joint melting solder -the heat is somewhere else - where the power is developped - the clue generally being a resistance. The motor in my heli - the bars in a fire. :)

[Canetoad]

If you are going to modify a 405, does it matter which one you start with? :scratch:

[Oldpinkman]

If you are going to modify a 405, does it matter which one you start with? :scratch:

Depends on the mods! You can pretty much bring a 405 to 405-2 spec, if you know what you are doing. The changes were mainly to the protection circuits and output transistors. The 405 struggles with a nominal 4 ohm load (so I use 8 ohm speakers). It can drive 4 ohms but isn't happy when the real load drops to 3.2. The 405-2 also had better speaker terminals and later ones had phono sockets, but you can change all of those things.

[DSJR]

The circuit layout changed quite a bit too and the mk1 went through several changes until the series 7 mk2 ones were launched I recall.

Patronised with bullshit? Apologies if it was me :(

[Barry]

Don't worry Dave! - I can give anyone "chapter and verse" on the circuit board/component values of all Quad 405 versions. I have a copy of the official Quad Service Handbook for the Series 4 Quad electronics: it covers both the Quad 44 pre and 405 power amps.

[Oldpinkman]

The circuit layout changed quite a bit too and the mk1 went through several changes until the series 7 mk2 ones were launched I recall.

Patronised with bullshit? Apologies if it was me :(

No dave - not you mate. Our friend stan telling me 12 watts would melt solder. See my helicopter thread :eek:

[DSJR]

Dunno about you, but I use low melting point solder with 2% silver in it. It's a very old drum (I don't do much soldering these days) but I think RS still make an equivalent.

Quickly back to the crimped connectors. I remember when I used to have to solder an external earth wire to the sub chassis-to-top plate wire on the Thorens 160B. The crimped tags Thorens used either had a coating on them or had natural oxidisation, since solder wouldn't 'take' to the tag without it being filed first. Blindly or otherwise, I'd follow the Linn practise of - top plate to sub-chassis, soldered link to tonearm earthing wire and then on to the amp. Sorry to mention it, but now TD160's are climbing in value, there just may be casual readers who stumble on this.