1 of 1 PCB manufacture - UK - Marshall Amplifier. - Page 1
Forum section: electronics / general

author: Supernaut
author_rank: Contributor
timestamp: July 13, 2025, 07:31:24 pm
content: .Edit by gnif: Post was defaced by the user who has subsequently been banned.

author: themadhippy
author_rank: Super Contributor
timestamp: July 13, 2025, 07:45:08 pm
content: That suspiciously looks like a valve state,the best sound they make is when ya takes em out to the garden and set fire to them.

author: TimFox
author_rank: Super Contributor
timestamp: July 13, 2025, 08:05:07 pm
content: Quote from: themadhippy on July 13, 2025, 07:45:08 pmElectric guitars and their matching amplifiers:The distortion cause by vacuum tubes (usually run without feedback) in guitar amplifiers, originally derived from 1930s public-address amplifiers using the new 6L6s, is part of the sound (along with the vibrating strings, pickups, and speakers).Those amplifiers do not work well for high-fidelity, but proper linear tube amps work fine for hi-fi, and help to heat houses in the winter.That amplifier is trying to exploit the operating characteristics of a 12AX7 low-power dual-triode, but chickens out to use solid-state for the power stage.

author: themadhippy
author_rank: Super Contributor
timestamp: July 13, 2025, 08:57:24 pm
content: Quoteand unfortunately instead of getting the best of both worlds they managed to give you the worst the two

author: TimFox
author_rank: Super Contributor
timestamp: July 13, 2025, 09:58:22 pm
content: Quote from: themadhippy on July 13, 2025, 08:57:24 pmMy impression of the sound from an electric guitar playing boomety-boom music is that the worse it sounds, the more it's liked.I prefer the gentle sound of the acoustic theorbo.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 13, 2025, 10:23:04 pm
content: If somebody else already reverse engineered the thing, then the most logical step would be to ask them for the design files. I find it quite silly to post the pictures of the PCB without the reverse engineered project.The schematics also seem to be easily available on the internet, and combined with the bare PCB pictures you have all the information that's needed to re-create the project.You can even create a project in KiCad, then load both the picture of the schematic in the schematic editor, and the PCB pictures in the PCB editors and then mostly place the KiCad symbols and footprints on top of those pictures and draw the wires and tracks. It's mostly a bit boring and tedious work. A 12 year old can do this, but I still recommend to do this only when you have a decent electronics background, because that is needed to verify what you're doing is correct, and you need it to analyze and correct mistakes. Without that background it can easily become a very frustrating project.

author: Whales
author_rank: Super Contributor
timestamp: July 13, 2025, 10:30:59 pm
content: QuoteTo me that sounds like thermal issues in the design, not in the materials of the PCB itself. The PCB would have to be taken well above 120degC for long periods of time to noticeably degrade, let alone blacken and char and become conductive.If you do not fully understand the exact cause of the heating issues then you will not fix the problem by re-manufacturing the PCB.Easier solutions might include adding a quiet fan (eg a 12VDC 120mm computer fan running at a lower voltage). Even the tiniest amount of airflow can have a massive impact in previously convection-only cooling designs.