Mr. Foxen

If you amp sounds bad, have a rebias before changing tubes, it drifts with time as they wear in. I think too many good valves get replaced when they've actually just reached a stable point.

[url="http://cgi.ebay.co.uk/SHUGUANG-EL84-6BQ5-6P14-NEW-PLATINUM-MATCH-QUAD-/110609080734?pt=Vintage_Electronics_R2&hash=item19c0d0a19e"]Here's a significantly cheaper quad of power valves for you.[/url]

[quote name='3below' post='1299055' date='Jul 10 2011, 04:03 PM']decoupling capacitors need to be larger or amp has inherent design flaw.[/quote] Are these the 0.047uf, 400v mustards roughly between the pre and power sections? It was suggested I replace these.

If that is 30w that would be EL84 not EL34, 4 of those gives around 100w. I got a set of 6 EL34 for £66 delivered. It is more of a case of a rebias after a year or so than actual tube death.

Would out of spec resistors in the pre cause the oscillation? That's the problem rather than noise, the noise is ok currently.

[url="http://cgi.ebay.co.uk/Yamaha-SBV-550-Bass-Guitar-/150630160715?pt=UK_Musical_Instruments_Guitars_CV&hash=item231241d94b"]Yamaha SBV[/url]

All of the electrolytic capacitors were replaced at the start.

[url="http://basschat.co.uk/index.php?showtopic=134869"]Here is the actual cure for those that need it.[/url]

I think my mate has dibs on this now. He is local, an could get hold of him while the auctions were live, annoying. Edit: definitely gone.

This is really low frequency, like you can see the cones slowly moving, rather than audible frequency. Plugging into the reverb return doesn't stop it.

Having a little play with this now the switch is replaced, an some resistors replaced to clean up some hiss. Noticed a new problem: the speakers are moving in and out really slow, too slow to make noise, like 5hz or something. Any clues?

Was anyone after the 24 track? The buyer no-showed, it was relisted, and the new buyer looks to be the same, so it might be going for a madly bargain price if someone can get it tomorrow.

Here is the 406, upon one of which I may have a lead. There are 3 styles of 406 (one is a 1x18") and I dunno which it is yet.

If you have a big saw, check out recovery places, have all sorts turn up, birdseye maple floorboards have been known.

[quote name='brensabre79' post='1293209' date='Jul 5 2011, 11:36 AM']I beg to differ. Its not just about matching cabs to drivers... put a 100w 4 ohm speaker into a 200w 8 ohm amp and you will soon see, the power will be too much for the speaker and the amp will be underloaded. result, blown speaker, blown amp.[/quote] The 100w that determines the point where that happens isn't the one the speaker is rated at, and is dependent on the box.

[quote name='Wolverinebass' post='1293202' date='Jul 5 2011, 11:29 AM']Does this thread mean that we'll soon be seeing adverts stating - CASH FOR NEODYMIUM!!! Send your old, disused bass cabinets in our pre-provided envelope to: PO Box 12345 Cash for neodymium BA55 SFA[/quote] [url="http://basschat.co.uk/index.php?showtopic=144388"]Far ahead of you dude.[/url] Catalytic converters are full of rare earths too, they were valuable as scrap anyway. And they are a legal requirement, which will cause some fun if the shortage continues.

[url="http://basschat.co.uk/index.php?showtopic=79008"]Have a read of this thread, covers lots of similar ground.[/url]

All that is wrong. Watts don't mean anything, and ohms mean not much, the bit that matches drivers to cabs are another set of specifications entirely. Predicting how speakers work in a box without actually trying is quite difficult, but if you throw up the box dimensions (ideally internal, it is the amount of air in the box that is important), and where the box has a port/vent/hole in it and how big that hole is, some people can make some more informed decisions.

Thing is they have to take the weight of a heavier lump dangling off the baffle, being dropped and stuff, so the weight has to come up some elsewhere.

[quote name='alexclaber' post='1292004' date='Jul 4 2011, 11:51 AM']Having discussed this matter with various large loudspeaker manufacturers the feeling is that with a bit of cunning you can do with ferrite what you can do with neodymium, just with extra weight.[/quote] So why didn't they do that before? Was it uneconomic?

If anyone has the green stuff, that isn't vinyde (disagrees with Matamps glue an makes Jeff sweary) I want to cover a sleeve for my power amp to match my slave.

Think his thing wasa Marshall Guvnor, the black one, LED clipping, maybe modded for bass, but his twin rig thing probably covered that. If you can get hold of one, it is a pretty simple two capacitor mod to open up the low end. There is a local chap who was making clones at one point.

Budget is the thing really. Tiny Terror is good for being small and dirty, and spending a bit on valves can make it do clean too. How much knob twiddling do you like to do? I'm gonna guess not much, the Hartke LH500 is minimal knobs and more of a clean machine.