JapanAxe

He has updated his listing to reflect what he has been told by potential bidders, so I'm call 'Not Tw@t'.

The knobs are off an 80s model like the Precision Lyte. The tuners are the lightweight ones that have been fitted to US Standards for a while. If it is a recent US Standard, I'm thinking there should be the option of through-body stringing, but no ferrules on the back. I'm guessing it's a bitsa.

I've had an MXR Carbon Copy die because the J-FETs in the switching circuit got fried by static (afaik).

Sorry to disappoint, but an incoming Ampeg PF-50T has somewhat disincentivised the bass amp project. When I do get round to a build, it is now more likely to be based on a Supro guitar amp like this.

Cheers, thanks for sharing.

Another vote for OBBM, especially for speaker cables.

I have a Neo D single coil installed in my Taylor. I will measure it when I get home. Btw I did have to modify it to make it fit, but that was because it was too close to the strings - I removed the top set of cork pads and replaced them with pieces of thin (1mm?) cork sheet.

So many amps, so little time!

Just ordered a PF-50T from Kenny's. 😎

The manual online says it's 400W at 4 ohms - and that's an old-school MOSFET power amp, should be plenty loud through a decent cab.

Leave the soldering iron alone for now. Assuming a passive bass, select one pickup only, connect your meter across the output. Slowly turn the appropriate volume pot through its range and note the maximum reading, which will be somewhere in the middle of the sweep. Double that for the approximate pot value. The nominal resistance of the pot will be a 'round' figure, so if you get 257k, that would indicate a 250k pot.

I am very conscious of this, but the Demeter has no top vents. I usually hang my bar towel on my guitar stand. I do occasionally have a problem with drummers putting their mobile phone on my amp or speaker, with inevitable ray-gun noises when it communicates in any way.

Rather fun actually. Regular gig at a large chain pub, which can get a bit over-lively. Slightly quieter tonight, but lots of young people dancing enthusiastically. Apparently there were quite a few 'freshers' out on the town. I was somewhat mortified to think that it is 39 years since I was a fresher myself! Anyway, I took my Mustang rather than the usual Precision, to give my fretting hand a bit of a rest. It sounded superb - I think it is probably the rockingest bass that I own. Here's me (looking like the BFG's nephew) and my rig:

Thanks! Another option was the AC30 output stage - I found the schematic for the 'bass' version on the Dr Tube website.

Just had a quick look at that schematic. The PI/driver is a 12AU7, and it will probably be simplest if I keep that in and follow the circuit from the wiper of the volume pot - before that will be my 6SL7-based B15-style pre-amp. Solid state rectifier for the HT - works for me, as I have no 5V secondary on my PT, and there is enough power available on the 6V heater secondary for four EL84s and four 12AX7s. Am I right in thinking that is cathode biased like an AC30? Yes there will, but first there will be a design-based thread in the Repairs & Technical forum, and in the Tube Amp DIY Builders Facebook group to which I subscribe (where you get people like Rob Robinette and Bruce Egnater chipping in with advice!)

Thanks @Bigwan, you are a star!

You may! I have just acquired (as scrap) a Carvin Vintage 33 combo. The cabinet is more than a little distressed, the speaker is blown, but both transformers work. My plan is to take the existing chassis and transformers (and some other useful working parts e.g. switches, pilot light) and convert it to a 30W bass head with the following features: Output section based around four EL84 valves, because that's what the OT is suited for - hence my interest in the LB30 schematic; Preamp based on a 1964 Amped B15 channel; That's about it! I need to make sure that the pre-amp will work with the power amp (i.e. that phase splitter has enough beans to drive all the EL84s), so I will be working on my understanding of push-pull amps and hitting up the forums . Here's the innards as I got the amp, and the almost-gutted chassis:

Thanks @Bigwan

Does anyone have a schematic for the Ashdown Little Bastard 30? Or at least the output section. I have a project in mind...