Quad 11 valve monoblocks - should I turn them on...?

[AnalogAlba]

Hello All,

I've just brought out my Quad 11 valve monoblocks after around 10 years of storage.
I had them professionally checked & rewired etc just before shelving them....

Should I get them checked over again before trying to use them?

Or...should I just turn them on and see what happens and stop being so cautious (or pathetic )?

Any advice greatly welcomed - thank you.

[PeterW.]

Hello All,

I've just brought out my Quad 11 valve monoblocks after around 10 years of storage.
I had them professionally checked & rewired etc just before shelving them....

Should I get them checked over again before trying to use them?

Or...should I just turn them on and see what happens and stop being so cautious (or pathetic )?

Any advice greatly welcomed - thank you.

a) I WOULD NOT turn them on without proper precautions. For two reasons - they are British and they are tube-amps. British-made goods with British-made capacitors have additional risks that US or some Euro-made tube amps simply do not. Not quite as bad as Chinese units under similar conditions - but bad enough.

b) Minimum precautions would be a metered variac (volt and ammeter) that would allow you to bring up each unit slowly and observe the amount of current drawn during the process. Note that tube rectifiers do not conduct below about 75% of rated voltage, so there is no "Slow uptake" on the filter caps. They see nothing until they are hit with 75% of full operating voltage.

c) And I would not connect speakers to them until the bias is checked and sure to be correct.

So, you are neither overly cautious or pathetic, you are merely being properly careful.

Peter Wieck
Melrose Park, PA

[Rothwellaudio]

They're British, therefore inherently unreliable? That's simply predudice. Quad amps are known for their reliability.
Personally, I would just switch them on. Electrolytic caps can age, but they age much quicker when in use, not in storage. Everything else won't mind a 10 year rest. Measure the total current drain and output valve current drain (if you can) to check that everything is fine before going ahead with long term use.

[Blue Angel]

They're British, therefore inherently unreliable? That's simply predudice. Quad amps are known for their reliability.
Personally, I would just switch them on. Electrolytic caps can age, but they age much quicker when in use, not in storage. Everything else won't mind a 10 year rest. Measure the total current drain and output valve current drain (if you can) to check that everything is fine before going ahead with long term use.

I am a British as well as an American valve amp user (Leak Stereo 20 and Dynaco SCA35)and have several other pieces of valve equipment. To me at least, there's no question of reliability between British or American gear.

I personally would never connect 220V ac after a prolonged non-usage period. I can't afford a variac but use an in-series lightbulb for several hours before feeding 220V ac.

I think there's a pic of the simple gadget I built in my gallery.

ba

[alanomt]

Hello All,

I've just brought out my Quad 11 valve monoblocks after around 10 years of storage.
I had them professionally checked & rewired etc just before shelving them....

Should I get them checked over again before trying to use them?

Or...should I just turn them on and see what happens and stop being so cautious (or pathetic )?

Any advice greatly welcomed - thank you.

a) I WOULD NOT turn them on without proper precautions. For two reasons - they are British and they are tube-amps. British-made goods with British-made capacitors have additional risks that US or some Euro-made tube amps simply do not. Not quite as bad as Chinese units under similar conditions - but bad enough.

b) Minimum precautions would be a metered variac (volt and ammeter) that would allow you to bring up each unit slowly and observe the amount of current drawn during the process. Note that tube rectifiers do not conduct below about 75% of rated voltage, so there is no "Slow uptake" on the filter caps. They see nothing until they are hit with 75% of full operating voltage.

c) And I would not connect speakers to them until the bias is checked and sure to be correct.

So, you are neither overly cautious or pathetic, you are merely being properly careful.

Peter Wieck
Melrose Park, PA

Hmmm, can't quite agree with this take on things. For many years I had a business importing and restoring American Jukeboxes (with tube amps), we certainly had some spectacular capacitor failures with those.

In the last couple of months we have had capacitor failures in a Kenwood amp (Japanese), an Ariston turntable (British) and even our dishwasher (German), nationality does not come into it.

For myself, I'm pleased to see how many British products, often of some age, are still in demand worldwide, this does not stop me from appreciating quality from elsewhere.

Alan

[josephazannieri]

Yo AnalogAlba:

I tend to agree with others that the best thing to do is to bring the amp up gradually, and give the filter caps a little time to "reform." My experience with measuring caps that are totally discharged from sitting for long periods is that they appear to the meter to be dead shorts at the time the meter is placed across them, and then they charge up and begin to show some resistance, and ultimately, they appear to be open when fuly charged. It doesn't take more than a few seconds for this to happen. As an old-time screwdriver mechanic, I don't have an engineering explanation for this behavior, it is just what I have seen over the years, measuring hundreds of caps.

This suggests that using some form of current limiting when hooking up any amp that has been sitting a while is probably a good idea. Either a Variac, or BA's easy-to-build lightbulb current limiter would help, and the amp ought to sit for a while in the current limited mode before just being shoved into the wall plug and switched on. From my experience, 5 or 10 minutes is enough. These precautions are from an excess of caution, to prevent a debilitated cap from failing on initial startup. I certainly would not give up trying the amp due to risk of failure on startup. If a cap pops, you can always replace it. It certainly is possible to just plug the amp in and have it survive the turnon just fine, but this precedure reduces risk. I use an old Variac myself. I got it many years ago from an old friend who used a bunch of them in a home brew stage lighting panel.

And good luck from that plugged-in old risk avoider,

Joe Z.

[Rothwellaudio]

Yo AnalogAlba:

My experience with measuring caps that are totally discharged from sitting for long periods is that they appear to the meter to be dead shorts at the time the meter is placed across them, and then they charge up and begin to show some resistance, and ultimately, they appear to be open when fuly charged. It doesn't take more than a few seconds for this to happen.

Joe Z.

All capacitors exhibit this behaviour because an uncharged capacitor is effectively a short circuit when discharged and charging current will flow into it rapidly initially, the current flow gradually reducing as it charges up. This is perfectly normal behaviour and what you are seeing on your meter is due to capacitor being charged by the current which the meter puts out to measure resistance.

Here's some info about the failure modes of electrolytic capacitors:
http://www.chemi-con.com/u7002/failure.php

http://www2.electronicproducts.com/Fail ... -html.aspx

http://www.elna-america.com/tech_al_reliability.php

However, I'd still just turn the amp on. If the main reservoir cap goes short circuit it should blow a fuse and cause no more damage. Using a variac is a good idea if you have one available but, personally, I wouldn't worry too much.

[PeterW.]

They're British, therefore inherently unreliable? That's simply predudice. Quad amps are known for their reliability.
Personally, I would just switch them on. Electrolytic caps can age, but they age much quicker when in use, not in storage. Everything else won't mind a 10 year rest. Measure the total current drain and output valve current drain (if you can) to check that everything is fine before going ahead with long term use.

YIKES!!!

RANT WARNING RANT WARNING RANT WARNING RANT WARNING

a) Electrolytic capacitors, if kept in constant/regular use will usually last indefinitely. I have some 1920s vintage radios that I purchased from the original owners who used them 'since-new' very nearly every day - and their capacitors test well and are just fine in use.

b) Yet, I have some NIB Display-only electrolytics from as recently as the 1960s from good names such as Cornell-Dublier, Sprague, Frake and similar that look brand new - but are dead-shorted or 100% open - mostly short. I would no sooner use a 40-year old NIB electrolytic capacitor than I would use a pull from the junkyard.

c) Low-value paper, wax or "Black Beauty"/"Black Cat" capacitors are accidents waiting to happen - and potted output transformers such as what appears to be in those Quads ain't nohow cheap.

d) A marginal electrolytic capacitor can allow a piece of equipment to appear to be working correctly - especially if one has no instrumentation to show otherwise. And give no indication of failure until the tar comes bubbling out from the power-transformer can.

e) How this happens: Say... a unit should draw 100 watts (for round figures) if all is well. So, the main filter array is slightly off - now it is drawing 115 watts. Probably not enough to make an absolutely certain naked-eye difference on a dim-bulb tester, nor blow most factory-fuses or circuit breakers. Those, really, are designed to protect real-estate not equipment (and I will spare all here my fuse-rant unless requested). But, that 15 watts will be expressed as *HEAT* somewhere within the system - typically in the power-transformer. Which, eventually, will fail under those conditions, especially if potted where heat is trapped more efficiently.

At the very best, your [wretched] advice is simply wrong. At worst your advice will lead to the development of a very expensive bit of slagged iron.

Further to Quad's 'reliability', from my direct and indirect experience with them - and from the literature available on the web, they have an excellent reputation for their iron and the sound they can produce. But several sites suggest that 100% of the resistors (in that model) be changed as they tend to drift, and that 100% of the capacitors be changed as they tend to short. Cutting the the chase "Just Plug It In" doesn't wash.

Now, I may be prejudiced against British equipment, but that is based on direct experience with the species. At the same time, I keep a decent array of test instruments including a ESR meter and a full-voltage capacitor tester. But I have learned over the 40 years or so I have played around with this hobby to test even brand-new, recent manufacture caps before installing them. With electrolytics, the off-tolerance/failure rate is about 2%. With film caps, the failure rate is vanishingly small - but the out-of-tolerance (especially for China-origin material) is also about 2%.

Humorous aside: Comparing Quad to Dynaco is a wee-bit unfair. David Hafler, the creator of Dynaco, was renowned for purchasing all his parts from the lowest bidder, at auction and at surplus sales. He did command quality for his transformers, and he contracted with first-line tube houses (Mullard, Telefunken, Sylvania & GE) but he would never use a cheap control when a cheaper one could be found. And it was quite common to find the "same part" from three or four different sources in one of his kits. He had no factory and no warehouse. He did not even package his kits. His "Headquarters" in Powelton Village (West Philadephia) was a three-bay former garage with a small office attached. Been there. His "Factory" was Drexel students on piecework - Look at some "Factory Assembled" products next to a kit - like-as-not the "Factory" unit had wire all of the same color, even looms and ribbon wire - but no two were alike.

He used packing services to receive components and parts from many sources, assemble them into kits, and then ship them as-ordered. His boxes had two different outer flaps, one saying "Factory Assembled" and one saying "Dynakit". How it was folded over was the only difference. So, he would never see anything going through his shop. That was all handled 'by others'. Much as his speakers were made, packed and shipped from elsewhere with just the name being on them. 100% horizontally integrated, to use his business model.

The Hafler "Factory" in Pennsauken, NJ (directly across the river from Philadelphia) was even smaller - a 2-bay garage with a very small office attached. Been there, too.

Quad, on the other hand was a first-line, always expensive name in the industry - more akin to McIntosh and Marantz than Dynaco.

Vintage equipment can be made to be as safe and reliable (often more so) than any modern item out there. Hobbyists have no accountability for costs and are not required to make a profit - and so may use parts and techniques of a higher quality or superior to OEM parts and techniques necessarily limited by the bean-counters. But, and for the record, in my experience, there is no reliable and direct correlation between initial cost and quality. Some manufacturers simply made good products at a reasonable cost. Some made cheap products at a low cost, some made very questionable products at exotic prices. And some made superior products at superior prices. But in very nearly every case, better parts and pieces than OEM are available - and should be used if needed.

As to variacs and such - I keep one of these ( http://www.oaktreevintage.com/web_photo ... _small.jpg ) please excuse the small picture. It is an isolation transformer and variable autotranfomer in one box with very good meters for voltage and amperage. Two scales on the ammeter 0 - 1A and 0 - 3A, each separately fused. Heath did make a 240V version - basically a different scale on the volt meter. I cannot convey how many times this device has save equipment and time during the diagnostic process.

Peter Wieck
Melrose Park, PA

[Rothwellaudio]

Well, the replies so far certainly cover the full spectrum. The fact that the amps in question are British seems to be a major problem to PeterW, despite going on to give details of American amps where the components were sourced as cheaply as possible from wherever they could be found and also stating that "Quad, on the other hand was a first-line, always expensive name in the industry".

To the OP, since my "[wretched] advice is simply wrong", feel free to ignore it. However, check the links I posted regarding failure modes for electrolytic caps to see what the manufacturers of capacitors say.
Basically, you have three options: 1) never switch the amps on again, ensuring no damage can occur; 2) just take a chance and switch them on; and 3) pay someone to test it somehow and hope their test procedure involves more than just turning it on.

[AnalogAlba]

Excellent to get so many replies..., to PeterW, Rothwell, BlueAngel, alanomt, & Joe – thanks all for taking the time to give me some advice – very useful – this is a great forum.

Well – much reading/absorbing to do with these responses – but I think, for now, I will be erring on the side of caution with these amps.

I don't have a variac or much in the way of test gear – therefore I will have to start looking in my locale for a helpful/tech-savvy amateur or a professional with experience of vintage and/or valve(tube) gear.

Oh and Mr R - your "3) pay someone to test it somehow and hope their test procedure involves more than just turning it on." comment made me laugh - very true - I will be sure to perhaps ask to be present at the turn-on or make it clear that I want some form of 'controlled' firing up - at least initially....

(but I will have to do it soon - my old Blue Note LP's are sounding awfy good - and that is before I have them coming through the Quads....)

[PeterW.]

Please note the interpolations:

Well, the replies so far certainly cover the full spectrum. The fact that the amps in question are British seems to be a major problem to PeterW, despite going on to give details of American amps where the components were sourced as cheaply as possible from wherever they could be found and also stating that "Quad, on the other hand was a first-line, always expensive name in the industry".

Yes, all true. But, several sites specific to Quad suggest that their resistors (British brand) are unreliablel ab initio. And all of them suggest that all the caps be changed (also British brand).

To the OP, since my "[wretched] advice is simply wrong", feel free to ignore it. However, check the links I posted regarding failure modes for electrolytic caps to see what the manufacturers of capacitors say.
Basically, you have three options: 1) never switch the amps on again, ensuring no damage can occur;

Sure. We all keep some shelf-queens that are kept for looks but either too much trouble, too risky or simply not worth the repairs. I have a Fada catalin radio and Crosley Dashboard radio that fall into that category. But I have no audio equipment of that nature.

2) just take a chance and switch them on;

Always possible. And the probability of a good outcome exceeds 40% for the short term, 0% for the long term. That 60% otherwise is a niggling worry to me, and the 0% is not so good either.

and 3) pay someone to test it somehow and hope their test procedure involves more than just turning it on.

That too. But a competent tech would never "just turn it on" - incompetent techs do exist, of course. But one would hope that the OP would ask around even a little bit.

Or 4) Make (at least) a dim-bulb tester for the preliminaries. Do some basic calculations on what the unit should draw, get a lamp one-size-bigger and see how bright it gets. Or borrow an fine-range ammeter. Or, as I did in the days before I could afford all the instruments I own today, shotgun-recap it and test the resistors with a sensitive VOM. And with that same VOM and a resistor of known-value place in series with the line-cord, calculate the voltage drop across it for the actual current draw of the piece.

There are many options other than learned helplessness. Generally I presume that anyone seriously into this and related hobbies wants to understand the process and the ins-and-outs of what they have. Whether they actually pick up tools is a different issue. Suggesting that anyone just plug in anything of this nature without (at least) a basic understanding of the possible consequences is irresponsible. Nor do I mind being a bit strident about my position. I have spent too much time replacing the very expensive magic smoke in vintage equipment to be otherwise.

Peter Wieck
Melrose Park, PA

[Blue Angel]

Peter W. Thanks for your most interesting recollections about the late David H. and Dynaco - a great character he was indeed.

@ AA

Since you are from Scotland and maybe a wee bit parsimonious, no?, here's a pic of my 'poor man's variac' which you can build yourself.

Parts list: Small project box from RS or Maplins, a 2A or 5A fuse and holder, IEC socket and lead, ceramic lamp holder, an IEC male to female lead and some bits of mains hookup wire and pop rivet's yer uncle

My take on this? Rather than getting fleeced by dicey unknown quantity techs, I reckon you are reasonably OK to try and waking up the Quads provided the ac goes either through a variac or the homebrew in a box. If the amps have gathered some dust during storage, vacuum first, taking care not to whack the valves. Also check underneath - NOT powered-up of course - for spiders and geckos which can cause an expensive blowup.

@ JoeZ

As always, I am ever so delighted to read your posts as always.

I'm sure all of us scribbling here would like to receive the news that the re-commissioning was successful and troublefree.

ba

[PeterW.]

Quite elegant. With a variety of lamps, you may test for a variety of conditions. With a good VOM amd a fixed 2-3A resistor of known value, you can even calculate current by the drop across it. 1 ohm or 10 ohm resistor are best as the calculation comes out 'even'.

I am spoiled rotten with a metered iso-variac - but needs must.

Peter Wieck
Melrose Park, PA

[Blue Angel]

Thanks Peter W.

Apologies - the pic was taken in the possible go ***POOFFF*** area of my workshop, the sand bags being just out of view, as was the 3M long wooden staff for the purpose of activating the ac switch

I think the occasion was the re-introduction to ac for a set of wood-sleeved Grundig tuner and amp which turned out yeah, well no fine as we say here in Cape Town.

Your meter is a lovely thing to behold.

Cheers. Let's have some more anecdotes from Melrose Park.

ba