Impedance and switching between series and parallel

I have two main combos that I use; my self-built SE-5a in a 2×10″ combo and my Fender Twin with the standard 2×12″.

I’ve got in mind modifications to both so that I can feed the SE-5a through the Twin’s 2×12″ and vice versa. The problem with this is that of matching impedance. The Fender Twin requires an impedance of 4 ohms whereas the SE-5A requires either 8 or 16 ohms.

All of the speakers in question are 8 ohm. For the SE-5a they’re wired in series for a combined impedance of 16 ohm and for the Twin they’re wired in parallel to give 4 ohms.

I needed to be able to switch impedance. After a few minutes of googling I couldn’t find what I was after so I sat down, worked out how to do it and thought it may be worth sharing for others in the same predicament.

With a DPDT (double pole double throw) switch I can make a pair of speakers switchable between series and parallel. With 8 ohm speakers this results in each pair being switchable between 4 and 16 ohms. Here’s the schematic.

Impedance Switching

Please note: I haven’t tested this yet. Once I’ve confirmed this is working I’ll report back but, for now, please treat this with scepticism.

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Voodoo Telecaster Sound Sample

Old friend Hedley Vick, down at The Harp in Little Neston, Cheshire, playing my self-built Voodoo Telecaster.

Guitar was plugged into a Roland Microcube and was recorded (video and audio) on a Samsung Galaxy S and I might add was late into the night and was preceded by several beers.

Going analogue

Over the past few months I’ve been pulling together a bunch of interesting and quirky pedals to put together a pedal board. When I was playing live more then my pursuit was for simplicity and reliability which lead me to the Line 6 Pod XT Live. Now most of my playing is back at home I’ve felt the need to put a foot back into the analogue world.

Here’s what I’ve got so far.

Left-to-right and top-to-bottom, they are;

  • Boss RV5 Digital Reverb – I traded this for a TruArc stainless steel bridge with one of the guys from the Gretsch Discussion Pages.
  • Digitec DigiDelay – Bought from another member of the Gretsch Discussion Pages.
  • Dod Flanger 575B – Kindly donated by fellow Six String Blissner, Doug Darrell. This is a really interesting pedal. It is an absolute beast and takes either two 9v batteries or a 20v DC power supply. I’m currently trying to track down a suitable power supply but if I can’t find one I’ll be building something.
  • Behringer UT100 Tremolo – A budget buy from eBay. I stumbled across it going for pennies within a couple of minutes of ending. One of my more successful snipes. Not a particularly robust enclosure but sounds brilliant.
  • Alfalfasprout69 Custom Shop Blue Alpaca (Way Huge Red Llama clone) – The one that started me off on this pedal board route. Custom made for me by Alfie, of Six String Bliss fame. Quite simply the mutts nuts of overdrive. This does absolutely everything I want.
  • FirstAct 222 Distortion – When Clint sent me the Crybaby this was tucked in the bottom of the box. A wonderful surprise. I’d put it in the same class as the Behringer Tremolo – not classy, not desirable, plastic box, sounds as good as any boutique pedal I’ve tried.
  • Nocturne Dyno Brain – I got this one from Pappy of FifthFret.org. A gem of a pedal. It replicates the preamp section of a Roland Space Echo. It has currently got a noise problem (that I suspect is a grounding issue) which I need to fix.
  • Alfalfasprout69 Custom Shop Tonekicker – This is a small 18db preamp that is designed to fit into a guitar, made by Alfie, but which I have housed in a small enclosure.
  • Dunlop Crybaby Wah – A donation from Clint Searcy of Searcy String Works fame. It has seen better days but within second of switching this one on it is obvious why it is a classic. It is easy to forget, with so many mods and clones available, the reason this pedal is so much modded and cloned is that the original is an absolute gem.

Guitar Portfolio

It has been a loooong time without a post. I’ve not forgotten you all but working away from home has completed diverted me from guitar/music projects so there has been little to document.

Tomorrow I’m attending one of those company “team building” events and, as an ice-breaker, we were asked to bring in a picture that will illustrate something about our lives that most of our colleagues wouldn’t know about. Here’s mine.

For anybody who has followed this blog for a while, there’s nothing new here, but it was very rewarding for me seeing them all in one place. Last year was a damn sight more productive than I had realised.

And for anyone interested in how I put the image together I used the “Collage” feature in Picasa. Very easy to get some interesting layouts in a matter of minutes.

Audio sample of the Jazzmaster

Here is a 1m30s sample of the Jazzmaster. It uses a mixture of the bridge and neck pickups. Recorded into Reaper using a clean amp model with a touch of reverb. The drums were done, as always, with EZDrummer and the bass was my custom 4 string.

NB: It was only after posting this to youtube.com that it occurred to me that the word “Jazzmaster” may be interpreted as some sort of hubristic comment on my playing abilities, particularly given the tune I chose. Nothing could be further from the truth. It is just a piece I have been trying to learn over the past 5-6 months, as part of experimenting with different time-signatures (both playing and recording them). It was the first tune that “fell under my fingers” when I hit record.

Setting up the Jazzmaster

Now that woodworking and assembly has been completed, the next job is to get it set up so that it plays as well as it can. For a new guitar I have found this is much more of an iterative and drawn out process, than setting up an old guitar. The neck relief in particular seems to take two to three weeks to settle in while the wood, truss rod and string tension all ease themselves into some sort of equilibrium.

Now I’m not saying this is the right order for tackling a setup, but this is the approach I use and it works fine for me.

  • Adjust the pickup height to be slightly lower than where you think the final position will be.
  • If you’ve got adjustable polepieces then, as a start point set them to a height that approximately matches the fretboard radius.
  • Set the bridge saddle height to be slightly higher than you think you’ll need.
  • A new set of strings is a must. Get them on up to tune,stretched and settled.
  • Make a quick check of the neck relief. I hold the string down at the first and last fret (using a capo helps) and at around the 8th or 9th fret you should have a gap between the fret top and the string that you could just slide a pick into. If you’re not sure about how to adjust the relief then head off to youtube.com and search for one of the many excellent guides.
  • With the guitar tuned and the neck relief close enough for now I then set the intonation.
  • I start with the high/thin E string. Play the 12th fret harmonic and then fretted at the 12th. If the fretted note is higher this means the string needs to be longer so adjust the saddle accordingly. Retune the string, recheck and adjust. Keep going until the harmonic and fretted note are in tune with each other.
  • I then set the D string saddle to about the same position as the E and go through the same process.
  • Next is the thick E string and the G string (I’m assuming an unwound G). I set the saddle about 4-5mm further back than the D and thin E, respectively. This gives you a start point that will be close. Then fine tune with the fretted/harmonic at the 12th.
  • And to finish off I set the A saddle between the E and D position, and the B saddle between the G and E. Again, this is just a close start point for the fine tuning.
  • The next phase of adjusting the action requires two separate adjustments; to the nut slots and the saddle heights. Because cutting the nut slot deeper is a one time deal (OK, it is not exactly but trying to raise a nut slot is a real PITA) I cycle round this many times, going slowly, just taking off a little at a time. I make sure the nut slots aren’t too high. I then adjust each saddle bringing it down and playing at every fret along the neck until I get a buzz. At that point I wind it back up a notch and then move on to the next string.
  • Once the saddles are about there, go back to the nut and check the slot height. If it is near-ish I leave it at that for now. It’ll get done properly after two to three weeks, once the neck relief has settled into shape.
  • Last job is adjusting the pickup height, which I described in detail a few posts ago.

One thing to bear in mind is that just because you can have a low action doesn’t mean you have to. For years I did everything I could to get ultra-low action on all of my guitars. I had assumed that, because one sign of a bad guitar is high action, low action was the sign of a good guitar. This is not true! I have found that a slightly higher action gives a much clearer sound and, for me, makes bending a string much easier. I feel that I can get my finger under the string and push it up, rather than trapping the string between finger and fretboard and squeezing it upwards. It does require more finger strength and tougher finger tips, but hey, that’s what practice is for.

Instalment two will be along in a few weeks but, in the meantime, if you’re interested in this topic then I would highly recommend that you head over to Billy Penn’s 300 Guitars blog and check out his guitar setup guide.

If you’re not familiar with the name, Billy is a guitar and amp tech (and shit hot guitar player) from New Jersey who has tirelessly provided many, many helpful posts and videos. And let’s get this straight – Billy is not some back garden hacker like me – he is the real deal. He is selling his guitar setup e-book for just $4.99. My first thought was that I’ve been setting up my own guitars for 20 years and have just about got the hang of it now, but I’ve had second thoughts… First off Billy has been so generous with his advice over the years and five bucks seems the least I can do to say “thank you”. Secondly, and perhaps from a selfish perspective, if I learn just one cool new trick that helps me setup or maintain my guitars better, that’s got to be worth it.

BTW: If you take your gear to a guitar tech I’d still recommend the guide. If you’re not doing it yourself then having a good understanding of what you’re talking about, or even of what to ask a guitar tech, is worth the five bills in my opinion.

Disclaimer: I don’t have any connection to Billy Penn, other than following him on Twitter and subscribing to his YouTube channel.

Finishing the Jazzmaster

I was just left with a few jobs to finish off the Jazzmaster.

I cut myself a bone nut blank from my stash.

Sanded it to shape and marked the string slot positions.

And checked the fit.

Normally I would fix it in place with a small dab of CA glue, but the fit is very snug and so I’m going to leave it as it is for now.

That just left me with giving it a final wax polish, installing the pickups, wiring it up, giving it a fresh set of Ernie Ball Slinkies and a rough setup.

There are a few jobs left to do, such as applying a headstock logo and making a truss rod cover, but I’m going to be too busy playing it for the next couple of days.

This one has been a smooth build. A couple of interesting challenges, a few new skills to learn, 10 days of work (in the region of 40-50 hours) over 18 elapsed days and a final total cost of £156.06. I’ll call that a result.