escholl

[quote name='4 Strings' post='907944' date='Jul 28 2010, 10:44 AM']I'll go along with escholl with 2 comments. If you've ever heard a Fender Telecaster, Fender-Rhodes piano, even a Fender Precision bass guitar ('course you have!), you'll come to the conclusion the designer/champion behind these instruments was a genius and knew a bit about sound. If he wanted to cut treble and a ceramic cap did it in the wrong way then I'm convinced he'd have used something else.

I suppose someone might be able to tell the sonic difference, if there is one, but would it actually be better?[/quote]
I don't know what the state of capacitor technology was in the 50's, but ceramic may have been his only viable choice at the time in terms of cost/performance, a tradition which likely carried on due to the very low-cost of ceramic caps. There is an interesting article [url="http://www.skguitar.com/SKGS/sk/CapTest/CapTest.htm"]here [/url]which seems to come to the conclusion the difference is present, but likely negligible. Personally, I would choose polyester/polypropylene, but that is likely just my prejudice from years of working with audio equipment.

[quote name='4 Strings' post='907944' date='Jul 28 2010, 10:44 AM']It's also said that amps improve as they warm up, my Audiolab hifi amp definitely does so, definitely warmer, deeper bass. Can't explain it though.[/quote]
As semiconductors conduct differently at different temperatures, the amps are biased for optimum performance at their approximate operating temperature, instead of room temperature. This is why they sound better as the amp heats up.

[quote name='LawrenceH' post='908052' date='Jul 28 2010, 12:00 PM']Not wishing to derail this thread but speaker break-in is very real and easily measurable. I've experienced it, in VERY obvious fashion, with a Deltalite 2510 II. Note that Eminence (and other manufacturers) specify their speakers after 'conditioning' to account for this phenomenon. Makes me wonder about judging pristine new cabs in shops.

Re caps, I seriously doubt I could hear/care about the difference, but would be interested to A/B and see![/quote]
The differences between a "broken in" speaker and one which is not, are in nearly all cases less than the difference between two of the same speakers -- that is to say the difference is less than the manufacturing tolerance for that speaker. If you are able to provide accurate and repeatable measurements to the contrary, than please do so, I would love to see it. However, all data that I have seen to date indicates "speaker break in" to be a psychoacoustic phenomenon, and more likely has to do with your ears getting used to the way that speaker sounds, or simply just the individual hearing what they expect to hear.

Edit: Slightly further research brought up mention of a paper published by David Clark and available through AES, which discusses measurable "speaker break-in" that occurs in the first few seconds of use, after an extended period of non-use. This is likely not the sort of "break-in" you were thinking of however.

[quote name='thisnameistaken' post='907280' date='Jul 27 2010, 04:32 PM']Yeah they are an arse. Maybe I'll file down the prongs on my plugs and melt my 4-gang flatter!

While I'm here who fancies PAT testing my gear? [/quote]

What about a custom power supply? I'm not in the UK at the moment so I can't offer my own services, but why not ask around and see if anyone would build it for you? You could always try two supplies, the first a small one with just a high-current 9V out and a 24 volt out, and then another normal one like the Gator you've already got to power everything else.

[quote name='dannybuoy' post='907636' date='Jul 27 2010, 10:05 PM']There are a load of cheap delay pedals with the same IC, it's a digital delay that sounds analog, plus you can even get it to self oscillate. Here's a kit for one:[/quote]

The ADL2 doesn't use the PT2399, whatever they use is an in-house design with their own markings on it. No information available beyond their chip number, AT34F512.

[quote name='PhoenixBass1' post='906801' date='Jul 27 2010, 10:51 AM']Yeh it is the MAG 300R. And ok thanks, so that means it's the amp head.

The noises are there when there's no bass attached. The preamp varies the buzzing a little and the master volume significantly increases the buzzing when turned up. Any help? Should i contact Ashdown then?

Thanks for your help[/quote]

Yes, if the preamp varies the buzzing level a bit, and it happens even with no bass attached, then you can be almost entirely sure there is something wrong with the preamp. The good news is it sounds actually like it would be a simple repair, most likely a dry joint somewhere although it could be a failed component. Either way, an easy fix for any competent tech. Yes, I would definitely contact Ashdown, give them a ring if you can, their customer support is well known for being very good so hopefully they will be able to help you.

The good news is, there is no way that the cable you used would have done this to the amp. You shouldn't use instrument cable, no, but in this instance it sounds like it is really just bad luck that it happened when it did. Even if briefly connected to a shorted load, most modern amps will have some sort of output protection and would not have suffered this fate, especially not when they'd just been turned on and weren't exactly delivering a high-power output at the time.

Sounds to me like a faulty power supply, should be covered under the warranty. In fact, if its only a week old, the store should do a straight swap for you.

free shipping though! bargain!

[quote name='GarethFlatlands' post='905377' date='Jul 25 2010, 11:57 PM']I think I read somewhere it's not properly analog although that may be incorrect.[/quote]
It doesn't use a conventional BBD, instead it uses something known as an application specific integrated circuit (ASIC) to achieve the same effect. As far as I can tell they seem to have produced their own chip that they can then source at a far lower cost, and yet still use analogue circuitry. Assuming they aren't blatantly lying about its function (which they could be), then the delay should be analogue.

I don't really know much about the company however, so this is just my interpretation of the engrish and specs on their site.

[quote name='Mr. Foxen' post='905346' date='Jul 25 2010, 11:07 PM']Should go wheely loud, but the tone might be rubbish.[/quote]

The Artec ADL-2 is supposed to be nice, and is fairly inexpensive. Not used one personally though, just heard good things.

[quote name='LawrenceH' post='904165' date='Jul 24 2010, 05:24 PM']Welcome to the world of science! If you're used to writing scientific articles it's pretty shocking when you realise the basis of how journos put articles together.[/quote]

lol, cheers, but I'm already there mate, for a long time now. And yes, it is shocking. I just never really thought of doing it for forum posts.

The 01V is a nightmare anyway, to do anything on that desk involves reading a tiny screen, nothing is intuitive, and on the one I used, the clip indicator was set higher than the clipping threshold of the pre's -- brilliant.

[quote name='Mr. Foxen' post='903701' date='Jul 24 2010, 01:05 AM']People really need to quote some sources when stating 'facts'[/quote]

I like this rule. I think I may start trying to do this, as much as is feasible.

[quote name='Mark Percy' post='903463' date='Jul 23 2010, 06:31 PM']valve watts different to transistor watts.[/quote]

Nope. Also, what on earth are you on about? There are plenty of drivers out there that match high sensitivity with high power handling. Cab efficiency in the low end has as much, if not more, to do with the size and construction of the cab as it has to do with the driver. Bassists 40 years ago got away with 100 watt amps because the cabs were BIG and the tone they were after wasn't the clean, deep tone that a lot of bassists want these days. Guitarists can still get away with it because they're not after much below about 100Hz, same reason they can use open-backed designs, they just don't need the lows. Clean low frequencies can take a lot of power, even in a fairly efficient box, hence the modern trend of amps with silly amounts of power, to power these little tiny modern cabs and still produce deep bass.

Also, I'm not sure what you're trying to say about cabs that have a much greater power handling than the amp? This never has been, and never will be, an issue. My amp puts out 250 watts, my cabs can take 650W at least -- I nor anyone else would not be better off by more closely matching the amp and cab power, that's not how it works.

I'm sure you're just trying to be helpful, so I'm not trying to have a go at you, honest, but there's enough confusion over all this stuff already.

I'm guessing from your sig the head in question is a MAG 300R? So it won't be a valve then, as this head is all solid state. I can help you narrow it down further and say, if it's just a constant buzzing, it's not the speaker either.

It sounds to me like there a broken ground somewhere. Does the amp make these noises even when there is no bass attached? Does turning up and down the preamp level affect the buzzing, and if not does turning the master volume up and down change it at all?

[quote name='Al Heeley' post='902935' date='Jul 23 2010, 10:46 AM']Basschat is great in that it caters well for both sets of demographic; those that think it doesn't make a difference and those that do.
Most of the latter school speak sense from the theoretical point of view, now the real issue is one of [i]significance[/i]. Does it make a significant difference to the human ear.[/quote]
Well, in [i]theory[/i], a ceramic cap approximates a near perfect form of capacitance, having almost no inductance and a low ESR. In practice, however, you would be hard pressed to find any low-mid to high end audio equipment, professional or otherwise, that uses them regularly in the audio signal path -- and even then, in the case of older equipment, they will often be C0G or NP0 (high stability, generally 1% tolerance).

Now, I'm the last person who's going to say you need a particular brand of capacitor to sound a certain way (12 quid for a paper in oil? hmm maybe not...) but in my experience, working on and listening to audio equipment, if it were me I would choose not to have ceramics in the signal path. There are simply better sounding alternatives. The only reason they were likely used in the original basses and guitars is because they are, in fact, so cheap.

Having said that, I am a man of science, and without having done my own measurements am somewhat uncomfortable with the idea that any benefits could merely be merely psychological. Just because an entire industry is behind an idea, doesn't mean it's true -- just look at the fallacy that is "breaking in" speakers, not to mention the new "neo tone". I want to believe there's no difference with caps, but I keep hearing one. *shrug*

[quote name='Clockworkwar' post='901795' date='Jul 22 2010, 12:20 PM']Where do I get the inputs from? Also how do I take the front panel out?

EDIT: Ashdown are sending me a free input jack.[/quote]

That is very nice of them!

I've not worked on this particular amp before, however there should be four screws in the top of the amp head, that, when unbolted, allow the amp head to slide out of its chassis through the back. You will then be able to unbolt the PCB from the metal chassis, and you will have to unbolt the other I/O connectors from the front, and unbolt the potentiometers as well. Once this is done you should be able to lift up the PCB and get to the underside of it, so that you can de-solder and remove the old input jack. As I say though, I've not worked on these specific amps before so these instructions could be partly or entirely wrong


Anyway, when you do finally get to the solder side of the board, it might be a bit tricky but have patience and you will get it out just fine. Make sure you've got a solder sucker and some desoldering braid, and it should come out easily. Remember, don't try to pry the old one out, too much force and you'll damage the PCB tracks. Good luck.

I've been inside the ODB3 before for a repair, it's not too bad at all. Here's a pic of the insides, courtesy of google:

[quote name='bubinga5' post='899294' date='Jul 19 2010, 07:20 PM']ok thanks WB...where exactly do i spray it..the cavity side is a PCB board...i cant get to the actual pots like say on a jazz bass.does it matter[/quote]

is there no way to remove the board?

Found [url="http://reviews.harmony-central.com/reviews/Effects/product/Pedalhacker+Mod/BOSS+ODB-3+Mod/10/1"]this[/url] rather enthusiastic review. Looks inexpensive to order the parts, and if you're handy with a soldering iron, why not? I would go for it

I would definitely not go with ceramic. Polyester film (which is what these likely are) may be relatively inexpensive but they're also good for audio, and are the ones most commonly used in decent quality audio circuits along with polystyrene, polypropylene, and metallised polyester.

[quote name='redstriper' post='898056' date='Jul 18 2010, 01:59 PM']Get a second opinion - saying that your sound is awful just before you go on is not what you want to hear and blaming the material used for the driver's magnet is ridiculous.
If he can't get a decent sound from your gear, maybe you need a new sound engineer.[/quote]
[quote name='Bill Fitzmaurice' post='898105' date='Jul 18 2010, 03:08 PM']That makes two of you. He had absolutely no idea what he was talking about either.
A knowledgeable sound man would know which frequencies were too much, and would simply pull them down in the mix.[/quote]

Both of these.

Would one of [url="http://www.rapidonline.com/Electronic-Components/Switches/Rotary-Switches/Rotary-switches/30304"]these[/url] do the job?

Yes, hopefully it will be obvious, as it sometimes is quite obvious, but other times it will be nearly invisible to the naked eye and you will just have to re-flow any solder connections that look questionable.

Attached image should show roughly what it looks like, although that is a particularly bad example and you issue may not be as obvious. There is also, of course, the chance that it is not a dry joint at all but something completely different.

[quote name='daz' post='897362' date='Jul 17 2010, 03:44 PM']I have just realized this only seems to happen after its switched on for 30 minutes or so and never before.?[/quote]

That sounds like it could be a dry joint then. I don't know if you're handy with a soldering iron, but if you are it should be fairly easy to spot if you look at the underside of the PCB, and a quick fix.

protection circuitry coming on maybe? either that, or it's probably a dry joint or loose connection somewhere in the amp.