JapanAxe

I’ve read that DC heaters can bring their own issues. Heater noise hasn’t been a problem in my other builds, and I can just try the options and see what works best. On all but my first build (which was a kit) I have drawn a full-size chassis layout so as to be sure that everything will fit without any parts fouling. I have chased the transformers...

Although it’s always sad to see our rig options reduced, I have to say my limited experience of Eden amps is not great. I used to play lead guitar in a band where the bass player was a serial amp buyer, and the Eden head he once used (Class D, gold colour, can’t remember any more) sounded very muddy to me.

Barefaced Midget Trace Elliot Elf Warwick Gnome Trend, anyone?

I tried to rearrange the central section of the layout to eliminate under-board connecting wires, but the new layout didn't really work so I ended up re-drawing the earlier layout. This time I added the volume control, which I may move to the other side of the tone stack. Now that I am happy with the board layouts, I have marked out the positions of holes for eyelets (dots), mounting screws (circles), and through-holes (diamonds).

I’ve been a convert to Barefaced for quite a few years now. For a small cab I love my One 10 for its gorgeous vintage voicing in a tiny package; for big gigs the Super Twin packs a huge punch and weighs only 17kg. There are plenty of options these days, all with their supporters. Why not buy 2 or 3 used alternatives through the BC Classifieds, keep what you like, and move on the others.

I have been carefully considering the grounding scheme for this build. I have rearranged the layout to employ a gound bus as described in Chapter 15 of Merlin Blencowe's book on guitar and bass preamps. All ground connections are made to the bus, which connects to the centre tap of the HT on the left of the drawing and to the input socket at the right. That is where it will also be connected to the chassis to set it at ground potential. The ground return for each amplification stage is made immediately after the ground connection of that stage's reservoir cap. The speaker sockets will not be grounded at the rear panel but next to the ground of C19, which is the reservoir cap for the phase inverter, as the NFB resistor feeds the PI grids. I have also moved the tone stack onto a separate board, which will be connected to the ground bus next to the reservoir cap for the first preamp valve. No other connections are shown - once the transformers arrive I will crack on with the full layout.

OK, looks like the Fuzzdog Dirt Dessert Harmonic Messulator.

Is the Prunes & Custard clone a kit, and did you build it?

Although root/fifth will get you a lot of the way there, there is a trick you need to know if you’re playing bass for bluegrass or indeed trad country. When changing from tonic to dominant chord, or from subdominant to tonic, you may find yourself tripping up. Here’s an example in D showing root/fifth for 4 bars of D followed by 4 bars of A. Note names are in lower case: d.a.|d.a.|d.a.|d.a.|a.e.|a.e.|a.e.|a.e.| The last note of bar 4 and the first of bar 5 are both a. This may sound ‘wrong’ because of the lack of movement between the two a notes across the chord change, and the temptation is to interpose an e note thus: d.a.|d.a.|d.a.|d.ae|a.e.|a.e.|a.e.|a.e.| However this creates a ‘skip’ that breaks the flow of the music. The Eagles on Tequila Sunrise just played it as the first example, but an experienced country bass player stays on the root in the bar preceding the change: d.a.|d.a.|d.a.|d.d.|a.e.|a.e.|a.e.|a.e.| You will hear this a lot in recordings. HTH

If I use a compressor on bass it is invariably as a limiter. Either a big-box Cali76 (which actually describes itself as a ‘Limiting Amplifier’), or the COMP/LIMIT control on my EBS amp. When I play guitar I have a completely different approach, using compression to produce obvious squash or sustain. If I’m having a bad night playing, no amount of compression will fix that. But I can kind of understand players worrying about becoming dependent on an effect.

It’s coming back to me. I think the guy had actually taped a copy of the suggested settings to the top of the amp for easy reference. One of the settings is called ‘Funk popping’ (not ‘Pop’).

I Googled B15T and that looks right. Except for the buttons. Maybe the guy just had a reference card of settings or something. EDIT: The B15T manual has 2 pages of suggested sound settings. Maybe he showed me that...

Who owns the PA?

Preset buttons?

It didn't look like any of those! The amp part was about 1U or 1.5U tall, about 15in wide, mainly black. I'm now starting to doubt whether it was actually an Ampeg or a flip-top, but it definitely had style-based presets in addition to regular tone controls...

The bass player in my first country band (in which I was guitarist) had a solid state flip-top Ampeg. This was around 1991. It was quite a compact unit that was attached to the top of a 1x15 speaker cab. I seem to recall that it had preset EQ profiles (e.g. ‘Pop’) that could be selected by push buttons on the front panel. So far I have been unable to find this mystery amp by the power of Google - any ideas? Just curious!

I probably won't get the transformers for another week as they are being built to order. In the meantime I have been considering my options as regards the heater filaments. The Ceriatone layout follows the Heritage schematic in having the heater centre tap connected to ground. I would normally do this, or in the absence of a centre tap on the PT I create a virtual CT using 100R resistors between each side of the 6.3V AC supply and ground. Both the 1964 and 1968 schematic show a 100R Hum Balance ('humdinger') pot across the 6.3V, with the wiper (marked K) connected to the cathodes of the output valves, which will be at about 36V above ground at idle. As I understand it, elevated filament voltages are intended to distance the heaters from any noise in the circuit ground, and the pot allows any residual noise on the 6.3V lines to be cancelled out. With proper grounding there shouldn't be any noise, but I think I will compare connecting the heater CT to the cathodes or to ground to see which produces the lower noise floor. If neither approach is satisfactory, I can consider adding a hum balance pot. If anyone has personal experience of heater noise in the B15 circuit, please do share!

I have started on a full-size layout for this build. As per my plan, the Ceriatone Aunt Peg uses just one preamp channel but provides the choice between cathode biasing (models up to 1964) and grid biasing (1968 models onwards). I have blown up the board layout to match the 70mm width of the phenolic board. To fit both cathode bias and grid bias components I would need to split the board into two sections. The PT I have ordered doesn't have a dedicated grid bias tap, but I could use the bias supply circuit from one of the later models that runs off the full HT. Alternatively I may just stick with cathode bias - this would be the more 'vintage' option, I don't need 5 extra watts at home, there would be less to get wrong, and I could easily fit everything on a single board. I would have a few components spare but there will always be another build! I am also tweaking the circuit in other ways, for example I will have just one input socket with a 33k grid stopper and 1M grid leak resistor, and I will be using a multiple star ground scheme as advocated by Merlin Blencowe. I have the dimensions for the transformers but I don't yet know where the leads will exit, so I won't go too far with the layout until I am sure of this.

I’m impressed that your bass hit the deck on the 1!

5 across: viva 7 across: limen 1 down: pulchrisima Sorry, 45 years since I did Latin...

Yes you need 32in scale strings on a Mustang to accommodate the extra length for through-body stringing.

My first guess would be the filter capacitors in the power supply. Electrolytic capacitors degrade over time and start to behave more like resistors i.e. they dissipate heat, which a healthy capacitor will not do.

In my guitar rack I have a 1985 Squier Tele alongside a Palir Titan T-type that cost me 10 times as much. They are both lovely instruments and both get gigged according to my whim at the time. Whatever works for you, do it, and fup the rest.