Mottlefeeder

A 'U' was originally 1 3/4 inches, and is now the metric equivalent. David

Nik wanted a Hercules bass stand and I had one sitting unused. A quick exchange of messages and the deal was done. Payment was promt and Nik confirmed when the item arrived. As others have said, deal with confidence. David

I was looking for a full-range plate-amp, and thought a sub amp would do the job, but I could not find one that did not have a filter that took out everything about 200 Hz. As Beedster said, it will sound like mud if all you are getting is the fundamental and the first harmonic. David

OK, I see where I'm going wrong - I assumed that getting a harmonic at the 12 fret by damping the string there meant that the node was at the 12th fret. From what you have said, the node is not there, but is close enough that damping the string at that point will produce the harmonic. The rest of it now makes more sense. Thanks David

Now I'm really confused. If I set the intonation so that fretting at the 12th fret gives the same note as the harmonic at the 12th fret, and the string break angle holds it firmly at the bridge and at the nut, why aren't the two half-string lengths the same? David

Just for information, the speakon sockets that allow jack plug connections will acept 2- or 4-pole Speakon plugs. The keyway that prevents 2- and 4- being swapped was in the bit they drilled out to fit the jack-plug. Presumably they only connect to terminals +1 & -1 and not to terminals +2 & -2. Doesn't help you but might help someone else. David

I'm not sure that I agree with that last comment. If you want fret 12 to be the midpoint of the string, then the bridge would be at 90 degrees to the strings, just like the nut. I think that what we are trying to achieve is to make the vibrating length of the string the same on both sides of fret 12. But, the vibrating length of the string is not the distance between the nut and the bridge, but a slightly shorter distance, governed by the thickness (mass?) of the string. So, even if you position the frets to accomodate these shorter vibrating lengths, they are still going to be a compromise across the string set. Which brings me back to my starting point, can you hear the tuning error, and if so, should we be setting the intonation to minimise the error in the part of the fretboard we usually inhabit? David

If you are not already doing so, try lubricating the tips before putting them in your ears - I find I get a better seal that way. Our harmonica player was advised to use hand cream for this, but I find saliva works well enough. Possibly the tips stay more centred in the canal or something along those lines. David

I have to say that I have never understood the reason for setting intonation at the 12th fret, other than the ease of comparing a fretted octave note with the harmonic octave note. Apart from fanned fret designs, surely minimising the error at the 1/2 open string length (12th fret) means that you will maximise the error at 1/4 and 3/4 of the open string length, and 1/4 open string length is where I spend most of my time. On that basis would it not be better to set the intonation to by right at about fret 7? What am I missing? David

Is that the yellow and purple one that's really noisy? David

If it should ever fail with a spectacular puff of smoke, the lack of a power switch might be regretted. That will also be the day it is so close to something else that you cannot easily disconnect the power lead. I would also suggest that you should be able to power down when you are having a break between sets. David

Channel B has the option of a line in or Hi-Z input for an instrument - so far so good. If you connect the 'through' output to your mixer and your tone changes, then you will know that option does not work for you. However, if you are only using channel B, could you use the active-speaker mixer-output as the feed to your FOH mixer? David

I have a PDF circuit diagram for a 2005 HA 1200 which shows no plug/socket connections between pre and power amps, but all 120 watts pass through the headphone switching contacts. That would be my starting point. With regard to the more powerful amplifiers, I have had both a Samson and a Hartke with intermittent faults that turned out to be the output relay. This one doesn't have an output relay. David Hartke Kickback HS1200 schematic.pdf

I posted a design for a one by 10 here, using the Eminence Basslite S2010 10 inch Neo speaker. The box is 30.5 x 32.5 x 39.5 cm, but could probably to tweaked to give you either a footprint or a baffle that matched your speaker: The cab plans were in a March 30th post. If you are anywhere near Manchester/Warrington, you are welcome to come and check it out. David

Bought Alex's BDI 21. Item was as described, communication was good and delivery was fast - thanks Alex. David

Most of those measurements are given at 3 m distance from the instrument - having several of them 1 m behind you must be horrendous. David

A more expensive mixer may well have higher quality opamps in it, or input circuits with discrete transistors as well as opamps, both of which would give you a better sound. Also, if you try and design a cheaper mixer with fewer opamps, some of them will be providing lots of gain, and may struggle to do so compared with a more conservative design using more opamps. That can also degrade the sound. I have small mixers by Behringer, Soundcraft, Mackie and Gear4music, and the Soundcraft and Mackie sound better. David

Mixer microphone inputs are designed for microphones of 200 ohms to 600 ohms impedance, so connecting an instrument to that (XLR) input will not work without a DI box. However, if that channel also has a line input, that is likely to have an input impedance of 10-30 thousand ohms, and a guitar or bass with a built-in preamp will feed into that without loss of tone. A passive bass or solid bodied guitar may work well, or may lose some treble feeding into that impedance - hence the 'Hi-Z' guitar input option on some mixer channels. A passive piezo pickup on an acoustic guitar will probably sound better feeding into an input impedance of about 1 million ohms (and using a short cable). In my experience, line inputs on mixers tend to be in the 10-30 thousand ohms impedance range, so if they have enough gain, they should work with any pre-amped instrument, but possibly not with passive ones. David

One point worth considering is that most guitars operate at about -20dB or -10dB, and most line inputs are intended for inputs at 0dB, so your guitar input could be x3 to x10 times too low. The cheaper the mixer, the less likely it is too have extra gain on the line-in channel to accomodate lower level inputs. David

Stripboard layout for the FDeck HPF Mk3 - note the first version has errors, corrected in the second version later in the thread. http://guitar-fx-layouts.42897.x6.nabble.com/F-deck-HPF-Series-3-td44880.html David

A bit of an unusual one for us - playing at the opening of the first part of Manchester airport's revamped Terminal 2 - first flight out 06:00. Went to bed at 21:30, got up at 01:15. On the road by 02:40. The new car park was apparently opened/signposted about an hour before we got there. Spent about an hour getting visitors' passes and getting our gear through airport security. Started playing at about 04:30. Played two short sets with a break for speeches and then packed up, handed in the passes and headed home. Got in at about 07:00. Nice audience (nothing else going on) and lots of money donated for Cancer Research UK. David

The Bulgin mains connector may not have the clearance distances between the terminals inside as specified for modern connectors, but that does not make it dangerous. For a device that will not be used by children, and will be treated with respect by its owner, 'replace as soon as possible' is a bit of an over-reaction. David