Author Archive | lois


Presonus Monitor Station Repair – Loud Buzz!

This presonus monitor station repair was posted to me by a customer who’d read my report on another presonus repair. The original unit exhibited a constant buzz and the customer reported similar problems here. Upon testing the unit, the problems I experienced on testing the unit were less severe, fortunately the experience with the previous […]

Continue Reading
Blackstar amp repair

Blackstar amp Repair – Series 1-45

This Blackstar repair was a simple valve amp service before the amplifier was sold. The amp is a series 1-45 2×12 combo. It’s a fantastic 2 channel amp with 4 modes, bright Clean, warm clean, Crunch and Super Crunch. The amplifier uses Blackstar’s DPR and ISF patents, you can read more about Blackstar’s DPR on […]

Continue Reading

MXR Carbon Copy Repair

I’ve talked elsewhere (here and here) about Carbon copy repairs and the ESD issue that causes the problem. I’m just going to take a moment to discuss the symptoms that show the problem in the carbon copy pedal. As I understand it, this issue has been fixed in new production units so if you’re buying, […]

Continue Reading

Silent Single Coil

Cancelling electromagnetic interference on a single coil guitar. Status: Ongoing Started: May 2012. Edited: October 2014 Edited: May 2016 Sound Clips Here’s a quick video of the test coil after it was fixed to my Godin. Summary A device can be created that replaces the backplate of a strat style guitar. This consists of a […]

Continue Reading
Behringer DC9 Frequency Response

Behringer DC9 Observations

This pedal is based on the MXR Dyna Comp, much like the Ross Comp, Keeley Comp, and others. The pedal uses an OTA, the LM13700 to limit the signal. For an in depth look at how an OTA based compressor works, see R.G. Keen’s Mine’s a niche use for this pedal – and I may attempt a […]

Continue Reading
MXR Repair

MXR Repair – Carbon Copy

This poorly delay pedal repair had the same problem as this MXR repair job from last year. This is a known ESD fault with Carbon copy delay pedals ‘of a certain age’. As you can see on the photo, this Delay pedal uses surface mount technology (SMT). This can be a little fiddly to repair, […]

Continue Reading
Carlsbro Repair

Carlsbro Repair – Cobra 80

Carlsbro Repair – Cobra 80 The owner of this Carlsbro repair complained of an intermittent crackling and occasional dropout. The fault was found to be within the power supply – a not uncommon source of trouble in bass amp repairs. One of the pins on the bridge rectifier had developed a hairline crack through the […]

Continue Reading