basstone

R140 looks like 350 ohms from this photo and R141 as already noted on the other side of the board. Worth trying a temporary "breadboard" fix with a standard resistor to see if it all springs back to life?

I trade as Hurstbatch Services, based in Wookey Hole, repairing all types of music gear. I'm happy to discuss any specific requirements.

It's possibly just a poor connection. Are all of the controls and switches working well and scratch free? Same for the connectors. It's also worth trying the jumper cable test between the effect send and return in case there is a poor connection in one of the jack sockets. Also a sharpish bang just with your hand when first switched on might help to confirm if there is a poor connection within the circuit? Next stage is to test to see if the DI output and effect send are also affected to help localise the fault. Pretty much whatever it is will require the amp to be opened up, inspected and then fault diagnosis and repair done. Any experienced engineer should be able to help you get it fixed. Good luck

Looks like a conventional class A/B power amp module to me along with auxiliary low voltage power supplies for the preamp, probably + - 15v DC. It is suspicious that the DI output is not working as that comes from the preamp, so the fault may not be the power amp at all or there may be multiple faults. It will also be worth checking that the thermal cutout (mounted on the heatsink) has good continuity. If the transformer is good (likely as it lights up) one option would be to replace the power amp if it is indeed the fault, with a readily available MOSFET power amp module. The power output might not be quite the same but I doubt that you'd notice the difference. Class D modules are available, notably Icepower, which are powered directly from the mains and handily have auxiliary DC power outputs for preamps, however these are not cheap!. You would need to figure out the preamp power requirements and either reuse the existing regulators or provide new and wire it correctly. None of this is technically difficult for an experienced engineer but it might not be cost effective, depending what value you place on the amp. Your best option of all will be to find a competent repairer who will accurately diagnose the problem and propose the best cost effective fix. There is an index of repairers on the forum, although probably a bit out of date now. Where are you based? I'm a repairer based in Somerset if you're anywhere near to me I'd be happy to have a proper look

Looks like R140 and R141 are both missing. Both small SMD items so not much power dissipation I think? Those solder pads also look damaged. It looks like the short was to the pillar on the left judging by the melted bit and black soot?

I'm a repairer based near to Wookey Hole, not too far away. I can't promise anything but happy to have a look if you can get the amp to me.

Agree to all of the above. In my experience Ashdown are great to deal with and always prepared to go the extra mile to help out.

Hopefully if the thread is kept active someone will spot it and offer to take a photo. If you can't get a photo, another, not so easy option, is to trace that part of the circuit out and figure out what the component does. Depending on accessibility and the board construction this could be tricky and time consuming! The only 2 variables are its resistance and power rating. There is hopefully some clue of power rating at least based on the size / lead spacing of the old component. Depending on its function, the exact value may not be that critical.

Can you be sure that this is the only faulty component? Has everything else been tested at component level? Unless the circuit and the failure mode is known there may be other issues lurking in there as well. Of course you may be correct and just a resistor is needed and it's certainly worth a trying a replacement if you can find out what the value is. The only other suggestion that I can offer is that someone else who has the same amp could take a photo of the circuit board to identify the value of the resistor in question. Anyway good luck with it.

Hi there, Sorry to hear that your Markbass combo is faulty. It's probably a back to Markbass or their approved repairer job as Markbass don't encourage or support independent repairers in my experience. It might be worth contacting them to get a quote as a starting point. Having said that, if it's a simple easy to find and repair fault any competent repairer may be able to help and if you know of one it might also be a lower cost option. Where are you based?

Try to listen to the bc112 project cab. It’s a bit bigger but is not heavy. It’s designed to work well on the floor but with good dispersion so you can hear it as well

Hi Adrian Is your second 10" cab identical to your main cab? if not they may not be well matched or even be out of phase, which could adversely affect the sound in particular the bottom end. It's always going to be hard to hear a 10" speaker on the floor, especially if you are standing to play your upright. Putting it on the floor does however make the bottom end louder as it's reflected directly off the floor. Have you tried tilting your amp / combo back, that is sometimes a good compromise. Your EA amps have good eq options so maybe dialing up the bottom end and cutting some top may help - although I expect you've already tried that! Finally if your pu is passive it will work best with a really high input impedance preamp. Not sure what the specs are of your amps? Regarding the use of DI and PA, if you get the sound you want in your amp and then DI post eq. from your amp a good PA / monitor setup should sound close to your desired sound. I personally never use a DI box between my bass and the amp. Again if you have a passive pickup the DI box input impedence will be affecting your sound. I play mainly fretless bass guitar and use a 1 x 10" custom built combo. I usually put it on a chair between me and the drums so that we can both hear it well. Hope that's some food for thought. Cheers

I agree with your conclusions, although the quest itself is fun and interesting. My next move might be to sell one of my jazz basses and invest in an NS design Omni bass. I would love to try one out sometime to see how they play and sound

Hope to be there again. Cracking day out! I wonder what new cab designs there will be by then!!!

OK thanks. Any other string suggestions welcome. I have tried Thomastik flats, which play and feel very nice but not quite what I'm looking for.

Is there any chance of a sound clip or two to demo these? They do seem to get positive reviews from all who try them. I'm looking for that elusive upright bass tone from my '78 fretless jazz. For about the last 15 years it's had a set of Rotosound trubass nylon tape wound strings, which work well and feel fantastic now that they are very well polished by use, but the nylon coating is getting very thin in places and I'm getting worried it might break and unravel at some point!

I've replaced loads of these barrel jacks, particularly on Warwick basses, which are otherwise very well made instruments. It's a neat and clean design feature but they do seem to fail fairly regularly (2 to 5 years) regardless of which make is used. It's also impossible to open one up to see what's going on, but peering inside with a good light it looks like the contacts are very small, narrow strips so I suspect over time they loose some of the required springiness needed to maintain a good connection. An intermittent connection is a real pain, especially on an active bass that's inclined to pop loudly as the power is applied when the jack is inserted!

Glad your still up[ for another bash next year, but please just try to avoid a clash of dates with the Stafford classic bike show which happens in October ....that's my other money pit (oh, I meant to say hobby).

Yes! I'll add my thanks to Mike and the team for another great day with fab food as always and good to meet faces old and new. Cab shootout was very interesting and good to know that the BC112 is well up there with the commercial cabs.

Try grounding different things with a wire to see if makes an improvement before spending time on screening to track down the dominant source of noise

Yes that would be great. It's really interesting to hear others cabs and chat about their experience and what works and doesn't as well as the design process and tools.

Spot on. These basses have a low impedance circuit. It will only work correctly with the 2.5K pots

This post is a bit old now so you may already have it fixed. I am an amp tech based in Wells and would be happy to take a look at your speaker. PM me if you are interested. From memory the master volume is a dual gang pot and it might be tricky to find an exact replacement. Spare parts at module level are usually available. The last repair I did on one of these was to replace the entire amp assembly. The cost was about £140 for the part and £30 to fit it.

I did a similar thing to a fairly noisy Warwick active bass with Nordstrand pickups. I was slightly surprised that I also had to ground all of the pickup pole pieces to make the bass really noise free. I used a combination of conductive paint (the kind used for car rear screen heater repair) and the self adhesive copper foil to get good continuity across the back of the pickup. This did not affect the tone but the bass was much quieter.

Looking forward to the bash tomorrow. Marshall DBS200 combo is now sold so I will bring my home build 1 x 10" combo as well as my BC 1 x 12 cab.