stevie

I ordered this one, Tim: <http://www.ebay.co.uk/itm/391490937364?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT>. That brand has quite a good reputation. Unfortunately, I've never heard the amp with the fan going - so I can't make a comparison, but I'll let you know what it sounds like when I fit it. People often make the mistake of fitting a quieter fan without realising the new one will run at a slower speed and will therefore not cool as well. Behringer specified a fan that runs at about 3,000rpm and that's never going to be really quiet. Because of the fan problem, I haven't played the amp outside the house, but I rather like it. I particularly like the eq, which I believe was nicked from Ashdown, but still - they probably nicked it from someone else.

Well, I finally got a reply from Behringer Support in the UK. It took a phone call and a bit of persuasion, as they seem to be scared to death of helping anyone fix their own gear in case they fry themselves. So, for anyone doing a Google search and coming across this thread ..... the answer is: brute force. Haha Undo all visible screws holding the chassis in (not on the feet and corners, of course) and then push like buggery from the back. (Stu_G and Twincam were right, sortof.) It took a bit of huffing and puffing, but it did finally come out - and the fan is as stiff as.... well, a brush. I've ordered a good quality 24V replacement and we should be in business again shortly. Interestingly, the case is 3/4" wood and weighs almost as much as the amp. I'm considering making a lighter plywood case, which should bring the weight down to under 10kg, I reckon. The handles bolt into the case, but I can't figure out how to get the two metal handle covers off. Unless anyone has a better idea, I suppose I'll try brute force on those too.

There is certainly a lot of nonsense on the web about amplifier damping factor. As far as I can ascertain, it only makes an audible difference if it is *really* low, i.e. below 5. The EAW person who wrote that article claims that a cable series resistance of .15 ohms will reduce the damping factor to an unacceptable level. I guess he must not be familiar with passive crossovers. Anyway, there is a video on YouTube where Andy, boss and designer at Matrix, explains that his standard amps didn't produce the kind of sound guitarists are looking for and that dropping the damping factor is what did it.

I'm sure one of our amp specialists will chime in, but I don't think the low resistance of a speaker cable makes much difference to the amp's damping factor. The first time I came across a variable damping option was in the Duncan Convertible combo (although it had been around for decades before that). It was a simple knob that allowed you to vary the damping factor from high to low. Lowering the damping factor gives a pleasant "bloom" to the sound together with slightly more warmth, which apparently makes the electric guitar sound better. The effect was certainly audible. Whether it's appropriate for bass depends on what you're after, I suppose.

It's worth bearing in mind that the Matrix was designed with a very low damping factor specifically for the electric guitar.

Thanks, McNach, that's most useful. It means that the fan is faulty and that I do really need to get inside to replace it. Still no luck though. I couldn't get in touch with the guy on the site BassBunny recommended because they claimed I was spammer(!). I've asked a question on the Behringer forum but I'm not very hopeful. It's at times like this that you appreciate Ashdown's quality of service.

Last week I played a song all the way through in the wrong key. It was one of those stupid keys like B major. By the time I'd figured it out it was too late. Nobody said anything. I don't think they noticed. That was a bit depressing.

Perfectly logical thinking, Frank, but I don't think that's it. And I wasn't teasing you - I was genuinely interested in your train of thought.

Thanks, Lewis. I get it.

[quote name='machinehead' timestamp='1476899510' post='3158314'] Oh I think you could explain it much better than me stevie. It was my day job for 43 years and I don't like talking shop. [/quote] Sorry to disappoint you, Frank, but I can't explain it either. It doesn't make any sense to me at all. The only thing I can think of is that the 12ohm cabinet isn't actually 12 ohms, but 16 ohms. It was a perfectly sensible question though.

There is a Harley Benton 2x10 cab on eBay at the moment for about £70 should anyone be interested.

I tried removing the handle, but that is not so simple either: there are no visible screws and you can't lever the end caps off without damaging them. Hmmmm. I called the nice people at Electronic Music Services in Southend and they didn't really know. I suppose that's good news because it means they probably haven't had one in for repair. They did say that the handle screws were unlikely to be screwed into the chassis though. Time to drop a line to the guy on the forum who managed to figure it out.

[quote name='machinehead' timestamp='1476888019' post='3158148'] Remember, we're talking overall cab impedence here and both speakers don't cover the same frequencies. [/quote] Yes, do go on.

I unscrewed a couple of the feet and the screws were just long enough to go into the wood. Thanks for the pointer.

It did cross my mind, but it wasn't immediately clear how to get to the handle bolts. I tried levering the handle covers off, but they wouldn't budge. I'll try again with a bit more force. Thanks. That could be it.

As the Subway amp costs the same from Thomann in Germany, it's more likely Mesa isn't giving its export customers a very good deal.

[quote name='Twincam' timestamp='1476630887' post='3155784'] Looking online it seems its just held in with 4 screws on the top. So it should slide out from the back or the front. Try pushing it from the back first. [/quote] I've tried pushing, pulling, banging and levering, and believe me, it is stuck. There are screws top (and bottom) holding the amp in the casing, but there has to be something else as well.

[quote name='BassBunny' timestamp='1476625881' post='3155710'] The fan shouldn't be related to Volume. There are 2 types, those that are on all the time and those that are temperature sensitive and only come on when the temperature in the case rises above a set level. So it depends on which type it is. [/quote] Yes, that's what I'm trying to find out. I can hear the internal fan, which is on all the time. As I'm using it at home at a low volume at the moment, the amp is not getting hot. It could well be that it only switches in when the amp gets hot, in which case all is fine. However, if the fan is faulty and I gig the amp, I could blow the amp and my speaker. The reason I want to get inside the amp is to test the external fan. Even then, it could be the thermistor switch that's faulty, which is why I'd like to know if the fan should be turning at low volumes. I'd give Behringer a call, but it's Sunday and I'm not sure I'd be able to find someone to answer the question anyway.

I've taken all the visible screws from the wooden case on my Behringer BX4500 head and the thing won't come out. It's solid. I even looked under the corners in case there were hidden screws there. Come someone tell me what I am missing? I haven't played this at loud volumes yet, but the fan on the back panel doesn't come on at low volumes. Is this normal?

It's likely to be the 12 K 3 PL model - 700 watts programme. There's only a certain amount you can glean from spec sheets, but it looks to be in the same ballpark as the Eminence offerings.

[quote name='obbm' timestamp='1474634081' post='3139448'] In addition they are response for post-sales warranty so if your Prodigy dies it will have to back to them for it to be fixed at their cost, assuming that it is still within the warranty period. All of this is paid for from the mark-up on the products they are selling.... [/quote] Sorry to nitpick, because I agree with everything else you have said, but the manufacturer normally refunds the distributor for repairs they have to carry our under warrranty. So that's not one of their costs.

Yes, kerbs and stairs are probably the big problem for dolly boards, although I've never used one myself. My trolley is a sack barrow type. I want to avoid cutting holes in my cab for rear castors, or spending money on a dolly board for that matter, when a separate trolley (which I already own) is the best solution anyway. I think I'll give the trolley a go first. Unless someone has a convincing argument in favour of another solution. Thanks for the input!

That's a step too far in the woodworking department for me, Mark. So the Barefaced uses 3-inch castors and large rubber feet at the front to make the cab level. OK. This is a lot more complicated than I expected.....

[quote name='bertbass' timestamp='1476291212' post='3153120'] 3 inch might be better as cracks in pavements etc, won't be noticed as much but you might have to raise the front of the cab a bit so that it's level. Another option is 4 wheels on the bottom of the cab and turn it on its side when in use it then becomes a high dolly and you can wheel loads of gear in at once. [/quote] OK. I think I get that. So with 3-inch inset wheels on the back, the cab would not be level. Would larger rubber feet on the front fix that, or not? The cab design is vertical and won't work properly on it's side. 4 wheels on the bottom should be OK in my limited experience, but it might be a bit top-heavy when moving it.

I'm now more confused than when I asked the question. So is a dolly board a better solution than a trolley or permanently attached castors?