Valve guitar amp voltage [UK] ???

Subject: Valve guitar amp voltage [UK] ???
From: GUEST,punkfolkrocker
Date: 12 Aug 10 - 09:13 AM

Please can you experienced electronics expert mudcat mates advise..

Since the EEC harmonised appliance voltage at 230V
and modern Valve amp manufacturers have been supplying 220-240V
amps to UK shops,
there's been some confusion as to whether its safe to save a few quid

[or hundreds of £££s in some instances]

and buy Amps marked 220-230V or 230V
from European discount shops like Thomann.

Opinions on guitar forums vary wildly:

Some say its no real problem and modern valve amps should be robust enough
to cope with any voltage variables / fluctuations between 220V - 240V..

Others argue quite firmly that UK voltage will definitely damage 220 - 230V circuits and valves
and thus need to be modified by a qualified techie
to run safely at our higher voltage..
and therefore it's a false economy to buy cheap from Europe
if you factor in the cost of a qualified amp engineers fees.

What do you guys reckon, ?????

I'm more inclined to trust mudcats more 'mature' advice
than some spotty know all kid on an average guitarists forum...

Subject: RE: Valve guitar amp voltage [UK] ???
From: GUEST,Lester sans Cookie
Date: 12 Aug 10 - 09:35 AM

Seems to be ok according to this link which seems to make sense

http://users.metro2000.net/~purwinc/seec2_2.htm

Subject: RE: Valve guitar amp voltage [UK] ???
From: Richard Bridge
Date: 12 Aug 10 - 09:38 AM

Do me a bleeding favour. Since when have any circuit components been rated to within 5%? Most of the separate electronic bits will be rated plus or minus 20%. Most of the instruments used to set bias voltages will have trouble being accurate to within 5%.

Subject: RE: Valve guitar amp voltage [UK] ???
From: The Fooles Troupe
Date: 12 Aug 10 - 09:43 AM

Well, actually that 'voltage rating' of 220-240V is an RMS rating for the sine wave mains supply. But non-techies don't appreciate that the ACTUAL PEAK mains VOLTAGE is higher.

And that this is within tolerances - so depending on just WHERE you measure the voltage, it can actually be higher or lower than these 'stated' values.

The peak is approx 1.414 time higher, roughly 315 V from memory ... not counting spikes... the difference between the resultant peaks is only a slight percentage...

Then there is the case of 'power factor' - where current and voltage are not in step - but one will 'lead' the other by a 'phase angle' and this sort of thing is why fluorescent tubes usually have a 'power correction fact capacitor' fitted to stop the current and voltage being 'out of phase' - which may actually result in damage occurring to circuits ... but we are getting pretty deep here ...


Now others far more qualified than me are sure to come along and give all the details...

"damage 220 - 230V circuits and valves and thus need to be modified by a qualified techie to run safely at our higher voltage.."

Arrgghhh - it's not as simple as that....

Components have maximum ratings eg capacitors have both Peak and normal working rated voltages (and are designed to tolerances). So it may be the case that the slight extra mains voltage may cause a component's rating to be exceeded - BUT, without actually at the full technical specs including circuit diagram, the component ratings (and the QUALITY of those components) and an understanding of just what the circuits are actually doing - some may be designed to 'buffer' slight overvoltages, etc - it's sorta like saying - in musical terms - that a march will ALWAYS be played faster than a waltz - a pretty meaningless and senseless generalising statement.

Subject: RE: Valve guitar amp voltage [UK] ???
From: GUEST,Ted
Date: 12 Aug 10 - 10:18 AM

Like Lester & Richard, I can't see any problem. If you're really worried, maybe get an autotransformer to step the voltage down?

Subject: RE: Valve guitar amp voltage [UK] ???
From: GUEST,Phil Williams
Date: 12 Aug 10 - 10:26 AM

Valve amps will be fitted with a mains transformer. If not dont use them. Many will have input tappings 200 (Hong Kong) 220, 230,240
so you may be able to select 240. Having said that, I wouldn't worry in slightest, the supply voltage to any place in UK will fluctuate quite a lot during the day. Just make sure its not set to 110v!

Subject: RE: Valve guitar amp voltage [UK] ???
From: treewind
Date: 12 Aug 10 - 10:54 AM

The current UK standard is 230 V ±10% (207 V to 253 V) which shows how much variation is to be expected. I don't know what tolerances are allowed in other countries.

I'd be very surprised if an amp decribed as "220V - 230V" failed on UK mains and if it did I would consider its design defective if it actually failed on less than 250V in normal use.

Subject: RE: Valve guitar amp voltage [UK] ???
From: John J
Date: 12 Aug 10 - 11:59 AM

I don't wish to split hairs....but:

Resistors (which will, amongst other things, determine grid bias voltages) will be carbon film 5% typically 250ppm / degC, more likely metal film 1% , typically 50 or 100ppm/degC (low noise, higher stability than carbon film).

Electrolytic capacitors are likely to be -20% / +80%, tantalum bead capacitors are usually much tighter tolerance.

Realistically (for audio purposes) the only close tolerance capacitors are likely to be 1 or 2% polystyrene, but they would only be used for tuned circuits / filters.

Ceramic, polycarbonate / polyester capacitors are popular in filter circuits - 'cos they're cheap.

Re: Operating voltage of valve amps - don't worry too much! An amp designed to run on 220v or 240v will happily run on either voltage.

The only REALLY voltage sensitive components you'll find in a valve amp are electrolytic capacitors and I would expect them to be very conservatively rated, eg: for 250v anode voltage, expect to see 350v (minimum) working capacitors. As a rule of thumb designers will choose AT LEAST 1.5 times the operating voltage for capacitor voltages.

Valves are extremely tolerant of over voltage conditions - they'll quite happily run at lower voltages too.

I hope I've not blinded you with too much science.

JJ

Subject: RE: Valve guitar amp voltage [UK] ???
From: John J
Date: 12 Aug 10 - 12:19 PM

I totally agree with Treewind's comments.

JJ

Subject: RE: Valve guitar amp voltage [UK] ???
From: GUEST
Date: 12 Aug 10 - 03:48 PM

"Do me a bleeding favour. Since when have any circuit components been rated to within 5%? Most of the separate electronic bits will be rated plus or minus 20%. Most of the instruments used to set bias voltages will have trouble being accurate to within 5%."

Ever since I've been building audio processing gear. Many circuits for studio gear specify 1% components.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Richard Bridge
Date: 12 Aug 10 - 04:31 PM

I must still have some old circuit boards lying around that I stripped for components back in the 60s. 20% was the standard tolerance. Still is for electrolytics.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Tangledwood
Date: 12 Aug 10 - 04:51 PM

Ever since I've been building audio processing gear. Many circuits for studio gear specify 1% components.

In that context the percentage is refering to the accuracy of the component's function in eg farads/ohms etc, not to the voltage tolerance.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Smokey.
Date: 12 Aug 10 - 04:52 PM

Just plug it in - it'll be fine.

Subject: RE: Valve guitar amp voltage [UK] ???
From: treewind
Date: 12 Aug 10 - 04:58 PM

"Many circuits for studio gear specify 1% components."

For resistor values, yes, and capacitors in frequency sensitive bits like EQ circuits, but not absolute maximum voltage ratings only 1% above normal working voltage, which is what we are talking about here.

Valves are pretty tolerant of overvoltage and excess power dissipation, more so than transistors. I doubt that valve heaters are all that bothered about a few percent over voltage either.

Subject: RE: Valve guitar amp voltage [UK] ???
From: John J
Date: 12 Aug 10 - 05:44 PM

You'll be lucky to get resistors with a wider resistance tolerance than 5% today, however electrolytic caps with a capacitance tolerance of anything as tight as 20% would be rather unusual.

As Treewind pointed out, the OP's question refered to operating voltages rather than component values.

I've run valves at double the maximum recommended anode voltage without a problem....electrolytics wouldn't be quite so forgiving!

Interestingly I've also run valves at low voltages (20-30v) and they've worked remarkably well in signal amplification applications, I've not used them in power applications though.

I'm going to get a beer.

JJ

Subject: RE: Valve guitar amp voltage [UK] ???
From: Richard Bridge
Date: 12 Aug 10 - 08:59 PM

I've been checking. In the 60s (the years of all the truly legendary valve guitar amps) most carbon resistors were 20% and bore no tolerance band.

Subject: RE: Valve guitar amp voltage [UK] ???
From: The Fooles Troupe
Date: 12 Aug 10 - 10:18 PM

Yep Richard, in 'basic electronics equipment' like audio amplifiers, 'more precise' is always more expensive, but rarely 'better'. :-)

Subject: RE: Valve guitar amp voltage [UK] ???
From: GUEST,HughM
Date: 13 Aug 10 - 08:08 AM

The general idea is that all the mains voltages within the EU are within the 230v +/- 10%. Therefore if the amplifier has been made recently for sale in the EU, it should be okay. Do check to see whether there is a "voltage selector" though, as mentioned above.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Bernard
Date: 13 Aug 10 - 08:21 AM

More to the point, the vendor of the equipment is obliged to ensure that it is safe to use, or risk prosecution. Whilst it could be argued that the purchaser also has obligations, the law will almost always find in favour of the 'victim'.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Paul Burke
Date: 13 Aug 10 - 01:38 PM

Back to the original query: if the amplifier is recently built, labelled "230V", and CE marked the manufacturer or importer has certified that it will operate within the range 230V +/- 10% safely. This includes the whole of the UK mains voltage range, so it will also be safe here.

Of course, the manufacturer or importer may have no basis for that certification, and by the time anyone complains, the importer may well have disappeared, the manufacturer is in Shangdong anyway, and all you can do is ask for your money back from the shop you bought it from, as they can claim reliance on the certification. If you buy secondhand, however, the onus is on the seller to ensure it is safe, by PAT testing. Hence all the Chinese crap you see on the market, and the notices in charity shops refusing to accept electrical goods.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Paul Burke
Date: 13 Aug 10 - 01:43 PM

BTW, drifting a bit off topic like everyone else, you can get aluminium electrolytics in 10% tolerance, and it surprised me that even quite big values are available- including a 400F (yes FARAD) capacitor. But it's only rated at 2.7V, and it's 60 quid.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Bonzo3legs
Date: 13 Aug 10 - 01:46 PM

My goodness - electronics enthusiasts!! I have build among others - Electroharmonix Guitar Synth, Drawmer DF320 noise reduction filter, Drawmer 251 Spectral Compressor, Aphex Aural Exciter B, ADA Flanger etc etc. Trouble is that there are few decent sources of components now in the UK.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Richard Bridge
Date: 13 Aug 10 - 01:46 PM

Try getting a 220uF (or thereabouts) 160V bipolar for a high power passive crossover.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Bonzo3legs
Date: 14 Aug 10 - 02:18 AM

I don't think I've ever seen a bipolar bigger than 10uF and probably rated no more than 100v.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Bonzo3legs
Date: 15 Aug 10 - 03:39 AM

Does anyone have a circuit diagram of the Aphex Compellor - included the potted bits which they think ought to be secret??

Usaians read "schematic" for circuit diagram!

Subject: RE: Valve guitar amp voltage [UK] ???
From: Paul Burke
Date: 15 Aug 10 - 05:12 AM

Here's one B3L- it'll cost you though:220uF 500V polypropylene.

My PCB CAD has been using "schematic" for at least 15 years. But sadly I've never even heard of an Aphex Compellor. It sounds like a device (or a spell) for firmly but humanely removing greenfly from your roses.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Richard Bridge
Date: 15 Aug 10 - 06:18 AM

I got a 220uF 160V non-polarised cap from Wharfedale for about 15 squid delivered for the crossover. They say no-one has blown one up before but that's not true because someone else had already changed one of the two in there (but he got his replacement from somewhere else). Farnell are a pain in the arse - unless you have the right sort of account they charge megabucks for cheap items because there is a minimum order. You can't just plastic an item and pay a modest delivery charge.

Incidentally, it's marked "Bugle 189-227uF" which is roughly 208uF plus or minus 10%

Subject: RE: Valve guitar amp voltage [UK] ???
From: Paul Burke
Date: 15 Aug 10 - 06:22 AM

I still think doing away with the power crossover, doing it at 10k impedance, and amplifying separately for the different speakers is a better way to do it.

Subject: RE: Valve guitar amp voltage [UK] ???
From: treewind
Date: 15 Aug 10 - 08:16 AM

Non polarized capacitors in the tens and hundreds of µF as used in crossovers are usually electrolytics. Electrolytics are usually polarized, but the NP versions are the equivalent of 2 Electrolytics back to back in series, which is why they cost a little more than polarized electrolytics but not as much as a polyester/polypropylene type of such high capacitance would be.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Richard Bridge
Date: 15 Aug 10 - 09:17 AM

At present that sub is being used as follows.

Desk (Behringers) has mono sub out with adjustable Low-pass - set to 250Hz

Driving an Ecler that I picked up for a song - I think it's an XPA3000.

It is alleged to be 2 ohm stable so I'm bridging the amp and running the sub off that - its 4 Ohms. Wary eye being kept on the protect light.

I normally use active X-over and 2 amps (pushing subs and tops) but the band does not like carrying the flight case with these in.

It might be handy some time or other to be able to use the sub off a different mixing desk and take the hi-out to run a top.

Subject: RE: Valve guitar amp voltage [UK] ???
From: pavane
Date: 16 Aug 10 - 05:52 AM

In case you think those electrolytics are expensive, have you seen the kettle lead that costs £2000?

Can't find the link at the moment, but it claims that its twisted silver-plated conductors transmit electricity from the wall to your amp at twice the speed of a standard cable, leading to higher quality sound!!! There must be one born every minute. (What about the 20 miles to the power station??)

Subject: RE: Valve guitar amp voltage [UK] ???
From: pavane
Date: 16 Aug 10 - 07:16 AM

$2700 mains cable

Subject: RE: Valve guitar amp voltage [UK] ???
From: Bernard
Date: 16 Aug 10 - 07:26 AM

That's even better that the grain-oriented loudspeaker cable where they claim you need to connect it the right way round to improve the sound... in an AC circuit?!!

Subject: RE: Valve guitar amp voltage [UK] ???
From: Bernard
Date: 16 Aug 10 - 07:31 AM

I see they are still perpetuating the myth about oxygen-free copper wire... which is only an advantage to the manufacturer, allowing them to draw finer strands more reliably...

I suppose they wouldn't sell any of this stuff if they actually printed scientific proof of their claims!

Subject: RE: Valve guitar amp voltage [UK] ???
From: treewind
Date: 16 Aug 10 - 07:34 AM

All copper wires are made of OFC!

Subject: RE: Valve guitar amp voltage [UK] ???
From: Richard Bridge
Date: 16 Aug 10 - 08:15 AM

I'm having a discussion with the bloke wot repairs me hi fi (I only play with the "hit it wiv a hammer" stuff) at the moment and he is giving it large about my needing to use at least 79 strand speaker wire for the HiFi (OK, I play it loud, but not 500wattsperchannel loud) - and more obviusly suspiciously to me he is giving it large about the need to use better quality "interconnects". I don't get it. The signal currents are tiny so why not just use flimsy phono-to-phonos?

I understand, of course, the need to use 4mm cable for stage subs that I am stuffing 3 kilowatts into.

I went and looked at some articles about bi-wiring (not bi-amping), too, and it looks as if there may be a tendency for bi-wiring to pass more total current (ie between both sets of wires) at the crossover frequency, and that is surely the last thing one wants since at the crossover frequency there will be the most phase difference caused by the capacitors, no?

Subject: RE: Valve guitar amp voltage [UK] ???
From: pavane
Date: 16 Aug 10 - 08:40 AM

It is all about taking money from the ignorant - and look how many people proudly claim to know nothing about science.

I suggest to anyone that if someone offers you such an item, you play it to them several times without them knowing which cable you are using, and see if they get it right each time. If they can't hear the difference, then it doesn't work. (Which, of course, it doesn't).

But then, that test is scientific, and many people don't believe in science (I wonder how they think their amp is designed?).

Subject: RE: Valve guitar amp voltage [UK] ???
From: Bernard
Date: 16 Aug 10 - 09:32 AM

Tell you what... let's stop being cynical, pretend we believe in all that junk, and set up a shop selling it to the numpties!! We'd all be incredibly rich!!

As for the A-B comparison tests, there's an easy way of faking it... or would that be slightly dishonest?!!

;o)

Subject: RE: Valve guitar amp voltage [UK] ???
From: Tootler
Date: 16 Aug 10 - 09:49 AM

Going back to the OP's query. My Father did two spells with NATO in Europe (He was in the RAF), one in France and one in Belgium. On both occasions he brought back stuff he had bought over there and it worked quite happily in the UK and this was back in the days before the EU when the continent was 220V and UK was 240V. The only "problem" was the need to change the plugs - or at least get a 2 pin to 3 pin adaptor.

The tolerances were such that the difference between the UK and continental Europe was of no great significance.

Subject: RE: Valve guitar amp voltage [UK] ???
From: pavane
Date: 16 Aug 10 - 11:16 AM

I have lived in Europe on and off for several years, and always used the same appliances in both countries with no problems

Subject: RE: Valve guitar amp voltage [UK] ???
From: GUEST,Auldtimer
Date: 16 Aug 10 - 01:11 PM

The 230v harmonised voltage is only a guide as to what you should expect at a scocket. This is 230v RMS which means that the voltage could be 220 - 250 - 260 even 300v or more, it depends on the split second you make the test. Whever when you check it with a standard volt tester this makes allowences for the vairation in voltage and comes up with a RMS voltage. The voltage, at a scocket is, the same now as it was before harmonisation. Nothing has changed, except the basis on which calculations that decide whither your supply voltage is acceptable or not are made.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Tootler
Date: 16 Aug 10 - 03:42 PM

Not quite Auldtimer, AC voltmeters for appliances should give you the RMS value. The tolerances given at the beginning of this thread will be the acceptable variation in the RMS voltage. Any appliance designed for 230V AC must be able to cope with the peak voltage. Referring to the instantaneous voltage is a red herring IMO.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Paul Burke
Date: 16 Aug 10 - 03:51 PM

There's a constant relationship between RMS and peak values on mains AC supply, where the harmonic content is carefully controlled. The peak is always 1.414 times the RMS. So designing it for 230 volts (with 240 volts within the tolerance range) also implies that it will tolerate the peak voltage.

Subject: RE: Valve guitar amp voltage [UK] ???
From: s&r
Date: 16 Aug 10 - 04:00 PM

RMS is the equivalent heating effect to DC. For waveforms that are sinusoidal (eg mains) the heating effect is .707 of the peak value of the mains. So from a heating perspective 240v RMS is the same as 240v DC through a resistive load.

Voltmeters usually give RMS for AC. For non sinusoidal waveforms they won't give true RMS

Stu

Subject: RE: Valve guitar amp voltage [UK] ???
From: bruceCMR
Date: 16 Aug 10 - 05:39 PM

Despite all the fuss about "harmonised voltages" between UK an Europe, virtually nothing has changed!

The "old" UK standard was 240 V ±6% (225.6–254.4 V)

The european standard was 230V - don't know the tolerance.

When the voltages were "harmonised", all they did was changed the tolerances. So it became 230 V+10%-6% (216.2–253 V), and is proposed to widen further to +-10% (207-253 V)

But all that changed was the paperwork. The power companies haven't changed anything. UK voltage is still typically around 240V, continental around 230. Both are within the tolerance of the new spec.

In many areas, your mains voltage, as measured at the socket, can vary by several percent throughout the day.

Most equipment doesn't care about exact volatges - especially switchmode supplies, which are generally fine on anything from 90-300.

The exception is light bulbs. A bulb which is nominally 230V, when put on a 240V supply, will run about 7% hotter and brighter, and will burn out more quickly. Beware when buying lamps for stage lights from european suppliers - most of the big names will manufacture 230V and 240V variants.

Bruce.

Subject: RE: Valve guitar amp voltage [UK] ???
From: Bernard
Date: 16 Aug 10 - 05:44 PM

Hah! "exact volatges" - you couldn't do THAT on purpose!!