4stringslow

The whole kettle / IEC thing is another example of modern language evolving and word definitions changing through popular usage. I'm pretty sure everyone here know that the mains leads we all use for our gear are not actually 'kettle leads', even if we don't know they are correctly an IEC lead, and even more correctly an IEC C13 lead and even more correctly a UK plug to IEC C13 lead (other countries are available). I'm also pretty sure that anyone at a gig asking for a kettle lead would be understood perfectly well Funny thing language.

Ah, may have been at crossed purposes (pesky Internet forums ). I agree with you about the input fuse.

Think in terms of power, which is voltage x current (amps) rather than just voltage alone. A 9v battery can provide only so much power and it can't be increased by doubling the voltage. If the voltage is doubled then the current will be halved.** This may or may not be a problem depending on the application, but it's something that has to be considered in the overall design. ** in theory. In practice the voltage doubling circuitry will not be 100% efficient so the total power out will be slightly less than the total power in.

[quote name='Misdee' timestamp='1470308825' post='3104928'] The fact is that the pound will not be recovering to pre -Brexit levels any time in the foreseeable future, not least of all because many in the financial markets believe that sterling was grossly over-valued for most of the last 35 years. [/quote] 35 years? Who are these 'many'? Many members of this forum might believe that, say, Fenders have been over-valued for 35 years, but if the market for fenders has sustained those prices for 35 years then I'd say that would be a pretty good indication of what those fenders were actually worth. That's not to say that circumstances couldn't change such that their value suddenly plummeted, but I'm not sure that's the same as being overvalued in the past.

Surely a 'bassist' is anyone who plays the bass part of the song? If that means it is played on a keyboard or pedals or whatever then fine, but it's still the bass part and it is being played by the 'bassist'. I realise this will sound pedantic but I read the topic title as bands that don't have a bass part in their music, whereas it actually seems to mean bands without a bass guitarist - a whole different thing altogether.

[quote name='Grangur' timestamp='1470340821' post='3105385'] Oh I appreciate all that. But what I'm saying is if you fill the bath at a rate of 15 litres a minute (100w) you can still discharge at 150 litres a minute (900W) out of the plug provided you've got a big enough plug hole and pipe to let the water fall out fast enough. [/quote] True, but that's just a larger scale example of my bucket one. You can only provide that 900W for a short burst before going back to 100W and even then you'll have to reduce the discharge to something less than 100W in order to refill the bath before you can discharge another burst of 900W. And if you work out the average discharge over a period of time you'll find it can never exceed 100W.

[quote name='taunton-hobbit' timestamp='1470340169' post='3105362'] Most (all?) of my amps/kit seemed to have 3a internal fuses - I've always used 5 as a catch-all (works for me) [/quote] Yes, but a mains lead is (almost) universal and can be used on any item of equipment with the same mains connector, so the technically correct fuse is one that can supply the maximum safe power through the mains lead. In the UK this is 13A. There are no advantages in using a lower rated fuse, only disadvantages. As you rightly say, your amp already has the correct fuse for its own requirements.

[quote name='Grangur' timestamp='1470338947' post='3105338'] This could be due to high levels of charge being stored in capacitors in the device, being discharged in bursts higher than the mains could supply. In the case of a welder, striking an arc will take a high current, but you don't keep that going for a prolonged period - usually only seconds. In an amp you may hit peaks of high output, but again, the high amplitude doesn't keep going ALL the time - otherwise your VU meter would simply sit on the red-line and never come down. [/quote] Yes, capacitors can certainly provide a peak of power but they are only discharging energy they have previously absorbed, so the average power output cannot exceed the average power input. Imagine a tap filling a bath. You can let the tap run constantly into the bath or you could repeatedly let the tap run into a bucket and then empty each full bucket in one great whoosh into the bath. Which method would fill the bath the fastest? The bucket may be able to supply a greater flow of water than the tap, but only for a short period of time. On average, the bucket cannot possibly supply more water than the tap.

[quote name='taunton-hobbit' timestamp='1470334573' post='3105281'] I, being mega-technical, tend to make sure that any gig leads have a 5amp fuse - its worked for fifty years, so I'm not stopping now. [/quote] Fair enough, just understand that it's really not necessary and that a 13A fuse is perfectly fine. If you lived in France or Germany or any other European country your mains lead wouldn't even have a fuse.

[quote name='TimR' timestamp='1470302330' post='3104840'] That would only transmit the frequency data though wouldn't it? Everything would just be at the same volume. [/quote] Sorry, I missed this earlier question. PFM would switch the light source on and off at a frequency proportional to the analogue input voltage. The receiver would use a Phase-Locked Loop to lock to the received signal (the on/off frequency, not the light frequency) and recover the analogue audio waveform. Solves the problem of AM linearity but it could be argued that transmission is digital because it is achieved by the on/off switching of the light rather than the brightness. In fact, given a minimum brightness for the link to work, the actual brightness of the light is irrelevant, which confers other advantages such as being almost immune to cable length attenuation effects or 'microphony' effects when cable is kinked or crushed or generally disturbed - though such effects are far less of an issue with a large plastic fibre than with a mono mode glass fibre.

[quote name='TimR' timestamp='1470313506' post='3105006'] Would this be better aimed at the PA market? A 64 core snake would be lighter than the usual copper balanced one, and more relevant for your application. [/quote] Depending on the value to the market, it would be technically possible to send 64 separate signals along a [u]single[/u] optical fibre. I know this to be the case as the company I used to work for was doing this with 128 separate video signals about 20 years ago, using Wavelength Division Multiplexing (WDM) - simplistically, multiple different colours of light

[quote name='opticfibre' timestamp='1470311916' post='3104986'] The frequency of the LED isn't changing just the brightness. Some people will say AM amplitude as its the amplitude of the light. people assume we are transmitting a frequency i.e 100khz and changing the intensity of the 100khz and modulating the signal on that.. but we don't transmit a frequency. The 660nm is just the frequency of RED light, but i see your point about 660nm being the carrier frequency and us changing the amplitude of it. Its similar to when we say optical, people assume its digital, Peter Jones assumed we were encoding and decoding. [/quote] Thanks for joining in - it's great to get some definitive answers! I'll admit to not having heard of IM (and I worked for an optoelectronics company for nearly 10 years!) but I suspect that's because it really is just another term for AM. You say you're modulating the power (intensity) of the light, I'd say you're modulating the amplitude (brightness) of the light. We're saying the same thing but just using different words. It does explain why your website states it's not AM (or the others) but I think it's a source of confusion. I can understand the digital assumption because almost all modern optical communication is digital, but digital doesn't necessarily mean ADCs and DACs because the signalling could be achieved by PFM (see my earlier link) which is a form of FM with various advantages over AM (or IM ). But perhaps the technical advantages are not necessary for this application and might even be a marketing disadvantage if you believe the market values a completely analogue system. That's a trickier judgement call! May I ask if the Dragon's offer made it through the contracts stage and you really did receive the funding for more prototypes?

[quote name='drTStingray' timestamp='1470263210' post='3104680'] I guess I fall into this category of having an amp (Ashdown ABM) that has been manufacturer serviced. It first happened because I blew it up - left a coat sat over the top of it and it overheated and went pop - Guy at Ashdown, an excellent chap, serviced it while I sat and watched and replaced the faulty bits [/quote] Isn't that a repair with a bit of incidental cleaning while the box was open? The problem was caused by the coat, not a lack of 'servicing'. [quote name='drTStingray' timestamp='1470263210' post='3104680'] Perhaps it's like servicing a car - in my mind it's far better to have one serviced and certainly if you're buying a used one the letters fsh in the description are almost obligatory - even better by the manufacturer's dealer etc. Similarly Rolex watches - if they're not serviced by an authorised outlet it invalidates the warranty. [/quote] Mechanical things are very different to solid state electronics, parts wear out and/or go out of adjustment. That doesn't happen with electronics.

[quote name='TimR' timestamp='1470263864' post='3104687'] No. It's a sealed unit, everything inside is SMT and there are no moving parts. [/quote] How many moving parts inside a solid state guitar amp? A fan maybe, but they don't need servicing as such. Even dust has to be really extreme before it causes a problem. Service stuff by all means if you worry about such things but I've never bothered and haven't had loads of failures as a result.

True, but even DACs are not necessary for a digital transmission system over optical fibre. PFM is another option. https://en.m.wikipedia.org/wiki/Pulse-frequency_modulation

[quote name='TimR' timestamp='1470258376' post='3104614'] My TV and fridge haven't moved an inch since I turned them on. My amp however... [/quote] Your mobile phone is, er, mobile - do you have it serviced?

Anything can be 'serviced' if you're that way inclined and have money to burn, but imagine doing it for every bit of equipment you own. No one has their TV or Hifi or fridge serviced do they, so why bother with a bass amp? I'm with the above posters who equate 'recently serviced' to 'recently repaired'.

[quote name='tauzero' timestamp='1470222232' post='3104168'] I don't know what's actually used as the transmitting and receiving devices as I haven't looked into it, but as broadband uses fibre, something must be able to modulate light at frequencies well above 20kHz, and something else must be able to respond to that modulation. [/quote] There are plenty of semiconductor devices that provide these functions. You can buy them online, eg http://uk.rs-online.com/web/c/displays-optoelectronics/fibre-optic-components/fibre-optic-transmitters/ I'm not suggesting that any of those devices are suitable for this specific application as I've not checked the data sheets, but it gives an idea about how mainstream these sorts of components actually are, and have been for decades. 20kHz modulation is really very, very low frequency stuff in the grand scheme of things. Could probably switch a simple LED at that frequency and recover the signal with a photo diode. Of course, you'd need to get the light down an optical fibre, which is where the packaging of those Tx devices I've linked to come in, but you get the idea. As TimR pointed out, BT (among many others) have been researching and developing optoelectronics for decades and run optical networks that operate at many GHz. The Light Lead technology really isn't the issue here and is nothing new - it's the application.

[quote name='12stringbassist' timestamp='1470226236' post='3104228'] I think the dragons would mainly have been interested in what else the technology could be applied to. [/quote] They might have been at the time, but a couple of hours of due diligence would reveal that this technology has been around for so long that AM was left behind decades ago, for pretty much all the same reasons that AM radio transmissions are rarely used these days. I'd be very interested to know what exactly their patent actually covers, because I can't believe it can be for the basic technology.

[quote name='AttitudeCastle' timestamp='1470217225' post='3104109'] Not too impressed by his response; however it's human nature to be protective over one's product design, and I agree YouTube clips are far from the [i]best [/i]way to compare sounds, the chap should test them before making a judgement, though no explanation, or constructive conversation was had... [/quote] Very fair point. I found it difficult to hear any difference in that YouTube clip, but that was probably because of the PC speakers I was listening through. [quote name='AttitudeCastle' timestamp='1470217225' post='3104109'] In the Kickstarter video, the explanation of change in sound from the normal copper cable (no indication of price point, but the DI test they do has a regular/high end/light lead comparison) and the Light lead, now from the explanation I believe I'm right in say it's then no different to a buffer (a people have pointed out already). [/quote] Yes, it's not really a fair comparison. What would be interesting is blind testing with a long cable, a Light Lead and a wireless link and all with an active and passive guitar. [quote name='AttitudeCastle' timestamp='1470217225' post='3104109'] Don't really have an opinion either way, beyond the science behind it seems very interesting, and it seem like a cool product, that as of yet I can't quite understand what it may be needed for! Hopefully David drops in here, and can give us a full explanation of the Light Lead! [/quote] My thoughts as well. There's no doubt it works but after that all the other claims seem somewhat subjective and possibly a bit over-hyped, though that's not an entirely unknown phenomenon with new products.

Precisely.

[quote name='bassman7755' timestamp='1470166270' post='3103822'] I disagree, yes light has a frequency but thats an irrelevant innate property of the transmission mechanism and there is no overt combination/splitting of a signal ergo the claim that its not AM is fair and reasonable IMO. [/quote] I agree that the frequency of the light is irrelevant (any frequency, or colour, of light could be used) but there is most definitely a combination of the signal and the light, because how else could the signal from the pickup be conveyed along a piece of plastic or glass? Look at it another way; the pickup electrical signal cannot be directly conveyed along an optical fibre because it's an insulator. The only way to transmit the signal is to somehow combine it with the light. In this case, by AM.

[quote name='TimR' timestamp='1470151164' post='3103633'] You don't need a balanced line for a guitar. The longest run is going to be 5m max. [/quote] Agreed, not entirely necessary, though even a high impedance 5m unbalanced cable is susceptible to noise interference and the longer the cable the higher the risk. It would do no harm to standardise on balanced cables. Not all mic leads are particularly long (eg PA amp on stage with the band) but they are mostly balanced XLRs these days so why not guitars?

Yes, I suppose you could. The important thing is to have three conductors. I'd say an XLR is a generally better connector than a jack, but it's a fair point. Are such connections widely used though?

Yes, I've often wondered why XLR connectors have not been more popular for guitar leads. A balanced connection would have many noise/interference advantages and the possibility of phantom powering could eliminate the need for batteries in active guitars. Such connections are well proven for microphones and would undoubtedly be just as effective for guitars. It would also mean a more universal 'signal cable' for all band equipment and eliminate the possibility (or near certainly in my band) of someone using a guitar jack lead as a speaker cable! Perhaps we just like to make things difficult for us all?