Mottlefeeder

OK - your back-up head (Elf or similar?) will probably have a jack socket output so you would need a jack plug to speakon to connect to the extension speaker and a speakon to jack socket to connect that to the combo cab. That would also give you the option of connecting the combo amp to the extension speaker if the combo speaker was suspect. David

Yes. Been there, done that - I once managed to connect my main amplifier output to my back-up amplifier, and only one survived. Your option of making your back-up amp have the same connection as the combo amp is the safest option to prevent two amps being connected at the same time. David

I built a kit which used 'Overlord of Music' hardware. It was fine for EADG, but useless for BEAD tuning as the string clamp bends the string through 90 degrees, and the B string would not take that. I ended up making an in-line clamp to get round the problem David

I'm trying to squeeze as much bass out of a small cab as I can, and the constraints I have accepted are that I need the steeper filter to reduce the port velocities. So my filter does not need to be variable, which makes things easier. With regard to digital options, the last digital circuit I designed was the logic behind a discharge-then-charge battery charger. I think it had eight gates in it. Also, learning new languages has never been easy for me, so I'm pretty much 100% anogue. I'll check out LTspice and see how steep the learning curve will be. David

It's funny how when you only have a hammer, every problem starts to look like a nail! Thanks for the info - I'll check it out. (And thanks for correcting my typo which I only noticed last night) David

Feeding WinISD'a filter calculator with the cookbook recommended Q per section for a two-section filter, I get two 12dB filters to give the same response as a 24dB filter. Unfortunately I cannot model the Rod Elliott twin 18dB filter design as WinISD only allows a triple 12dB design. But that gives me a design that I can work with. David

My understanding is that the Q defines the sharpness of the knee, and that also affects the likelihood of ripple. The Butterworth 'design' maximises the range of the flat response, and the WinISD Butterworth graphs show no ripple. Chapter 16 of the op-amp cookbook @tauzero linked to does show graphs for various filter configurations. David

Thanks @tauzero - towards the end of chapter 16 there is a comment that to achieve an overall Butterworth response in a multi-section filter, each section should have a different Q. That implies that the copy-and-paste sections in the FDeck and Elliott designs are approximations, and the WinISD calculated responses are correct. I'll have a play in Win ISD and see if I can get a two section filter to produce the same response as their composite one. @nekomatic - as far as I can tell, the Q defines the sharpness of the corner, and is not related to the slope of the curve further downhill, so for example with a high Q, low order filter, you could have a high peak at the corner followed by a relatively gentle slope. David

The busking band are out pretty much every weekend, doing 5 hour gigs in all weathers, sometimes on both Saturdays and Sundays. That makes our annual total about 70-75 gigs. Pre-Covid we were out almost every Saturday and Sunday and doing sheltered accommodation gigs some afternoons and some parties in the evenings. We peaked at 180 gigs in one year just before Covid, and that included nine gigs in seven days in the run up to Christmas. A few years ago I told the BL I would be cutting down to three gigs a week, and this year I am doing one 5 hour gig most weekends. I no longer have the stamina to do two 5 hour gigs on successive days. David

I'm confused! Rod Elliott's 36dB rumble filter uses two cascaded 18dB sections and he says it has a combined Q of 0.707, making it Butterworth. FDeck's 3rd generation 24dB HPF uses two 12dB sections and global feedback to sharpen the corner and make it Butterworth when both the variable and fixed frequency sections are tuned the same. However, WinISD gives you different responses for two cascaded 12dB Butterworth HPF filters compared with one 24dB Butterworth HPF filter. My question - Does cascading two HPF filters, each with a Q of 0.707, give you an HPF filter with a Q of 0.707, or is the Q related to the sharpness of the knee, so a steeper filter will have a higher Q? David

Loose Change Buskers routinely play one 5 hour set once or twice most weekends. The back line is there for the duration. The two 'front line' singer/guitarists alternate songs and play for either one or two hours, swapping in fresh singers one at a time and as slickly as possible. David

When I checked with Warwick whether I could convert my jan1 from EADG to BEAD I was told I could, and sent a replacement screw for the one string position that was not compatible with its new string diameter. That's the sort of thing they are for. David

We've recently been using a battery pack to power a Yamaha 500+500w one box mixer/amp, and my Ashdown MyBass 500w head and when the battery runs down, the mains goes off and the amps shut down - no fuss and no damage. One thing I would look out for is any small power supplies that are not switched-mode. Small transformers, e.g. in older fx pedal supplies, can get fried by the harmonics generated by cheap inverters, but with modern gear, that issue is becoming less common. David

I couldn't see the linked advert without joining the Facebook group. David

I have a mix of hardware and plans to cover scenarios with spares and things we have in use. For example: The band uses a one box mixer and pa amp, so I carry a spare mixer and cables to feed it into my bass amp, and out to the pa speakers. We often have to use a 3rd party's generator which sometimes fails, so my backup rig is battery powered and the spare mixer can also be battery powered. And so on... David