Stewart

Marshall JCM900 Breaking Valves

A Marshall JCM900 Breaking Valves was the cause of this amp’s failure. It travels around a lot and it has the original 1990’s valve retainers on the output valves. The original ones fitted to this 4102 model are shown below.  These are fitted over the 5881’s to hold them in place. The issue is that an amp is well gigged and in and out of vans suffers a lot of vibration. These holders rub on […]

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Fender Bassbreaker 007 Image

Fender Bassbreaker 007 Red Plating Cure

  Quick Intro to the Fender Bassbreaker 007 The Fender Bassbreaker 007 is a cute little valve amp. There are two versions – a head and a combo. It has two 12AX7 pre-amp valves and one EL84 output valve. It has a 10 inch Celestion speaker. A nice compact practice amp. Check it out on the Fender website. Fender quotes this amp as 7 watts audio output in the manual. It does not say whether

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Vox AC30/6 1964 Interior image

New Website Trade Area

A brand New feature for amp techs and amp makers We have  a  brand new ” Website Trade Area” for amp techs, service folks and amp manufacturers. Click on the Logo/Register button  on the top left of our homepage. Then complete the simple form.   We might ask some questions. When the account is apporved, you will receive an email asking you to change the password.  A username will be allocated. Make sure you have

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AC30 vibrato image

Loads of Payment Options

Worldwide Payment Options We accept American Express, Mastercard and Visa worldwide. We also accept Paypal. European Specific Payment Options Austria and Germany- EPS, SOFORT Belgium – Bancontact The Netherlands – iDeal Poland – Przelewy24 China Specific Payment Options Alipay Coming soon : WeChat Pay

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Sovtek 12AX7 WA WB WC image

De-Mystifying Sovtek 12AX7 WA WB WC Variants

De-Mystifying Sovtek 12AX7 WA WB WC Variants I thought it worth the time De-Mystifying Sovtek 12AX7 WA WB WC Variants. Why are there three versions of the Sovtek 12AX7 and why use one versus the other? One common characteristic of all three types is that they are very low in microphonics.  The “W” in the part number is there to tell us its a ruggedised valve.  Ruggedised valves are made to withstand more vibration than

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Marshall JCM900 Chassis image

Marshall JCM900 100 Watt Combo

A Marshall JCM900 100 Watt Combo  arrived in the workshop.  This version is the 4102  It was very poorly. The first issues seen were : 10 amp fuse in the plug!! Low power output and VERY  loud mains hum Pots noisy Amp plays a dying gasp when amp switched off Pops / crackles and very low volume. The valves were tested on an AVO MkII and CT160 tester.  The preamp valves were down to a lot

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Marshall JCM2000 DSL amp image

JCM2000 Bias Drift UPDATED Mar 2025

Note: We now have a new, superior solution to Marshall JCM2000 bias drift issues. Find the details here. The early (1997-2003) Marshall JCM2000 DSL50, DSL100, TSL100 and TSL122 amps are often troubled by an unstable bias (drifting bias). These are nice amps and I have one myself This can be difficult to diagnose correctly, as it can take half an hour or more of testing and/or playing before this Marshall JCM200 bias drift shows up.

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