Subthumper

Hi, some interesting points here. My question is, are neo drivers actually more expensive to make than ceramic ones or are neo ones more expensive because they're light? It seem the cost of a neo equivalent cabinet is horrendously more than its ceramic counterpart and as someone said most of the cost is the cabinet (though in many cases I fail to see where the money goes). Just

Hi what is the actual problem or symptoms that the amp is exhibiting? And is the problem in the pre or power amp? The Ashdown stuff is pretty easy to work on and getting the PCB's out is a doddle, just watchout for the wires going to the VU meter as the VU is stuck to the chassis with glue or double sided tape. Also dont forget to mark up where any wires go to if you have to disconnect them. If your looking for bad solder joints get a good light and a magnifying glas and methodically work along the solder side of the board and have a good poke and prod of joints. Flexing the board slightly can also show up any component leads which are moving inside the solder. If you do have to resolder anything its best to completely remove all the old solder and make the joint good from scratch. Then touch up anything that looks like it could cause a problem. Hope this is of use. Cheers Just

I'd suggest getting it looked at. There's a number of things that could cause this problem. Get the valves tested-all of them, and as suggested get the bias checked and have the tech check out the power supply and smoothing caps. As said 100 watts of valves should be pretty loud even through very average cabs. Good luck Cheers Just

[quote name='Mr. Foxen' post='1125014' date='Feb 12 2011, 03:09 PM']There isn't only one flavour of dirt. The best drive sounds come from adding dirt at multiple stages a little bit at a time. If you feed an amp a dirty signal, it can either make it the same but louder, or distort it more, making an increasingly dirty signal at each stage. The power amp distorting is another link in the chain, but a necessary step in getting that to drive is hitting it with a lot of signal that it correspondingly produces a lot of signal, and thus, generally, a lot of volume, and with the power stage, you don't have much by way of means to cut that volume.[/quote] Hi, interesting you should say about the multiple or cascaded gain stages as I recently serviced a Burman guitar amp with such a pre amp. Its a completely different way of getting your sound as it is possible to affect the tone and not just the gain and drive of the circuit by adjusting the three gain controls. Sounded fantastic and got me thinking it would be fab for a bass pre amp (if maybe with a little less gain and tweeking of the tone stacks). Not sure what the Burman bass amps had in terms of controls so maybe one the Burman owners could fill us in. Sorry to hijack the original thread but had to chip in. Cheers Just

[quote name='icastle' post='1125895' date='Feb 13 2011, 01:02 PM']Try [url="http://music-electronics-forum.com/attachments/9026d1271855035-ashdown-abm-schematics.pdf"]these[/url].[/quote] Ah many thanks. Looks to be just what I'm after. Cheers Just

Hi all I'm after a schematic for the above. In particular the power amp. Any help very much appreciated as its completly fried, or if anyones fixed one of these before are there any common problems to look for other than the chared remains of the output IC's? Cheers Just

I'm only saying what I found in this particular case. The mesa website seems to only give an output rating of 4 ohms. I'd have thought that a £1500+ amp would have better information on itself and no I'm not going on the walkabout megathread. Mesa can do their own research considering their gear is grossly overpriced.

[quote name='wateroftyne' post='1120223' date='Feb 8 2011, 04:06 PM']You'll find a 4ohm Walkabout will will run happily at 2ohm, too...[/quote] The one I was asked to fix did'nt. Though only blew its fuses. Not an amp I want to do too much surgery on.

[quote name='Phil-osopher10' post='1119595' date='Feb 7 2011, 10:41 PM']So I have the walkabout scout and it has two outputs that say (8Ohm) beside them, is it possible to run just one 4Ohm cab off it?[/quote] If its the combo I believe the impedance of the internal speaker is 4 ohms allready, which means the amp will be running at 2 ohms if you connect another 4 ohm cab to it.

[quote name='SignsOfDelirium_bassist' post='1095056' date='Jan 19 2011, 12:52 PM']Yea the first pot would be series/parallel, but the second is gunna be the phase switching. Kinda worried that perhaps if I set this all up, I won't be able to have series + out of phase? if making it series cuts out the second vol pot...[/quote] Hi again, the phase reverse makes no difference to the series parallel. So you should get, 1. neck 2. bridge. 3. neck and bridge parallel in phase. 4. neck and bridge in parrallel out of phase. 5. series in phase 6. series out of phase. Mine has 2 vol controls so as I said before dont forget to turn both volumes up when using series switching. You'd need a triple pole double throw switch in order to revert to one vol control when using series and I dont know if any one does one on a vol pot as a push pull but I could be wrong. Cheers Just

[quote name='SignsOfDelirium_bassist' post='1091014' date='Jan 16 2011, 12:29 AM']I'm gunna be buying new knobs anyway, right now I've got the chrome ones that come with the VMJ, I want the more authentic looking black ones Only just dawned on me that they'll probably say on the sale if they're split or solid So the only question remains is...Anyone know where I can get an out of phase switch (Is it just another 2-way switch? But wired in a certain way?)? And of course, a diagram telling me what the hell to do with it would be pretty handy [/quote] The phase switch can be another DPDT push pull the same as the one for the series parrallel so you wont need to drill any holes in the control plate. You only need to reverse the phase of one pickup. This shows you how to wire it. [url="http://www.proguitar.de/Support/PickUpSchaltungen/PickUpPhaseSwitching/PickUpPhaseSwitching.html"]http://www.proguitar.de/Support/PickUpScha...eSwitching.html[/url] You'll have to work out which way you want the switch to opperate. Good luck Cheers Just

[quote name='SignsOfDelirium_bassist' post='1091014' date='Jan 16 2011, 12:29 AM']I'm gunna be buying new knobs anyway, right now I've got the chrome ones that come with the VMJ, I want the more authentic looking black ones Only just dawned on me that they'll probably say on the sale if they're split or solid So the only question remains is...Anyone know where I can get an out of phase switch (Is it just another 2-way switch? But wired in a certain way?)? And of course, a diagram telling me what the hell to do with it would be pretty handy [/quote] The phase switch can be another DPDT push pull the same as the one for the series parrallel so you wont need to drill any holes in the control plate. You only need to reverse the phase of one pickup. I'll have a look for any links to circuit diagrams. Cheers Just

Hi I did this on my Tokai jazz fretless using a push pull pots (I think Hotroxuk sell them). Its quite a subtle change of tone so dont expect to be blown away but its definately different. I also put in a phase switch too which gives you a massive range of sounds, in fact six different possibilties. Dont forget to turn up both pickups when using the series mode, although you can get a certain amount of tonal change by varying the volume controls. A few of the sounds are quite thin and I always regarded them as better suited to recording. Anyway its worth doing but take care with your soldering and wiring. Good Luck Cheers Just

[quote name='Lemming16' date='Jan 14 2011, 05:11 PM' post='1089550'] Hi everyone. I bought the Acoustic 220 few months ago, and yesterday i bought the Ampeg BSE410H. The Acoustic 220 is rated: 160 Watts RMS at 2 OHMS 125 Watts RMS at 4 OHMS This info is according to the original Ad. [url="http://acoustic.homeunix.net/twiki/b...ic/BassHead220"]http://acoustic.homeunix.net/twiki/b...ic/BassHead220[/url] And my cab is an Ampeg BSE410H. ( [url="http://www.ampeg.com/pdf/BSE410H_HS_HLF.pdf"]http://www.ampeg.com/pdf/BSE410H_HS_HLF.pdf[/url] ) It is rated at 200 Watts RMS at 8 Ohms. My question is... do these 2 get along? i really dont know much about this things, but i guess not, since my Acoustic 220 would give me like 80 watts...since the cab is at 8 ohms... Does this mean i should get another head? Im taking a look at the GK MB200...the ultra portable new GK heads. Hi, if the cab has four 8ohm speakers you could have it rewired to 2ohms by putting them all in parallel. Or get a tech to put in a series parallel switch so you could still use the cab with other amps. If the amp has'nt been serviced for a long time I'd recomend doing so, so that any preventative maintenence can be done and see what the ravages of time have done to it. You'd be surprised how good some of these old amps can sound after a bit of tlc. Cheers Just

[quote name='thinman' post='1047501' date='Dec 4 2010, 04:21 PM']Basic fault finding really - e.g. see if a power rail has ripple on it, check a signal fo clipping, funny harmonics. Agreed, it matters not if the signal is delayed but I think it necessary to be able to see the signal accurately represented.[/quote] Hi, does it have to be a USB? If its only for what you've listed then why not look for a bench one second hand. I recently picked up an old British made one (vintage it has valves) for twenty quid off of gumtree. Also the other consideration worth looking at in the scopes spec's is maximum input voltage. I looked into USB scopes when my old one died but found that many had only a low max voltage which would be a setback if you ever want to use it on any valve equipment (though many a time I would love to stick 500+volts into a computer). Just my thoughts. Cheers Just

Hmmm are they doing that amp as a straight amp head?

[quote name='stevebasshead' post='1037768' date='Nov 26 2010, 01:44 PM']If you use the squirty electronics cleaner stuff make sure you get the one with lube in it, there's different formulations for different purposes and pots ideally need the lubed version.[/quote] Hi, use Deoxit (expensive but very good) or Peavey Funk out (got deoxit in). They dont have aggressive solvents in them and wont attack any of the plastic components in the pot or dissolve the grease which gives the pot its smooth feel. Deoxit is also very good at resurecting the most crackly sounding pot and is great for cleaning any sockets and connections. Cheers Just

Hi try these guy's, they're pretty good for rare and obsolete stuff. Not always cheap but can usual get most stuff. www.dalbani.co.uk/search.php Good luck cheers Just

Good stuff. What make are the transformers and where can they be got?

Yeah great amps built like a tank and lots of watts. Also as mentioned a fair few tone and hookup options. Good bang for the buck. Cheers Just

Hi, I did some work on a svt 4 this year and though it was a different fault it was a bad solder joint which having trawled through numerous forums seems to be a common problem on these, even though ampeg themselves dont seem to aknowledge this problem. Its the first place I'd look, though it ca be a time consuming process. Also make sure all the efects send and return sockets are clean and not causing problems. Check the fuses too as if it were a problem with the mosfets they would uaually blow. Look for the simplest solution first. Good luck cheer Just

Hi all I just serviced a Fender rumble 100 combo and its useless feature is... Led's that get brighter as you play harder which are located in the vent at the bottom of the cabinet. Really useless. I'm hooked, anyone got anything more useless than that? Cheers Just

[quote name='mr.sibs' post='982305' date='Oct 9 2010, 09:35 AM']They are both dimarzio pickups which have in turn - a red for hot (you can see these soldered above to the central pole of each vol pot) a green which is ground (soldered to the relevant back of pot) and a balck and white wire which are twisted and soldered together then wrapped with electrical tape. Is this correct? I am not sure about shielding further than this I tried the multimeter this morning and all components seem to be consistent with levels of resistance in relation to each other, i tried pots, bridge, jack. So I may now try the cooper shielding and just put her back together! Thanks[/quote] Looking at the pic the body of the pots are'nt connected together. They are relieying on the foil on the back of the control plate and sometimes this isnt enough. Wire them together. Afraid earthing is a bit of a never ending subject. You could do a degree in it and someone will still argue the toss or something wont work. Also try soldering a wire to the jack earth and touching it on various other parts that should be earthed to see if the hum/buzz dissapears. One other thing, have you tried it with a different amp? Make sure that isnt the problem. Good luck Cheers Just

Hi, its difficult to see from the picture but are the wires that come from the pickup shielded or two seperate wires (usualy red and black)? if its two seperate wires make sure they are twisted together, this will prevent alot of hum and buzz. If they are shielded types then you have another problem so as amentioned check all your earthing connections.

Very nice loada stuff you got there. I've just seen the mesa 400+ on ebay. Is it you that is selling it or did you get rid of it some time ago? Out of interest do you have any schematics for Roost amps? I've been asked to fix one but the power supply seems to be configured differently to the schematic I've found on the Roost website and is driving me a little crazy. Cheers Just