DC Resistance

A customer asks; “Can you hot up my Strat single coils to 8k?”

Sure, if looking at DC resistance (DCR) figures on a multimeter was the objective, we can wind to hit a DCR target every time but we’re not just aiming to hit DCR, we're aiming for great tone! The trouble begins when folks try to extrapolate figures that aren't fully understood. In this case, the customer has heard a 6K pickup, has decided it needs more power, has a calculated guess at what that power increase should be, and throws out the 8K figure. Here are a few facts about DCR in relation to guitar pickup design.

For a given length of wire, the thinner the wire gauge, the higher the DC resistance figure will be.

With standard 42 gauge wire used on most Strat pickups, any winder will struggle to see much over 7K DCR before the bobbin is physically full of wire and the coil is spilling out the sides, unable to fit a cover onto the pickup. DCR here on a full bobbin will be somewhere between 6.8 and 7.3K, depending on wind, tension, wire type and insulation thickness.

So, we can go for a thinner wire gauge, 43 gauge. Winding this to 8K will sound a bit thin, because other values like inductance have shifted. This will not offer the power increase the customer is looking for. 43 gauge only begins to have sufficient power output around ~10,000 turns, when the bobbin is again close to full. With 43 gauge wire, DCR as a consequence of achieving a good sound may show a minimum DCR around 9.5K and go right up to 13K before the bobbin is again, full. The same again is true of 44 gauge wire, though we can fit around 14000 turns into the same bobbin.

This is why you will typically see a range of Strat pickups from ~5.5-6.5K (42 Gauge) then a gap where you rarely see DCR figures of 7-9K. Then you start to see some higher DCR figures emerging at ~9.5-13K (43 Gauge) and you’ll see a few specialist high output pickups around ~14-15K (44 Gauge).

Seeing a DCR of 6K and multiplying it by two does not double the output. There are a huge range of factors involved, all beyond the scope of this page. By shifting wire gauges and increasing turn count we can increase output, but the DCR is a consequence of the pickup design, not a deciding factor in how a pickup will sound.

Some data - A typical Strat bobbin wound to show DCR of 6K using different wire gauges +/- ~200 turns

8000 turns of AWG42 = 6K (Bobbin ~ 7/8th full)

6600 turns of AWG43 = 6K (Bobbin ~ 2/3rd full)

5600 turns of AWG44 = 6K (Bobbin ~ ½ full)

One of the tactics deployed in cheap, aftermarket pickups and by some guitar manufacturers is to use AWG44 to hit a recognised DCR figure like 6K. The spec can be listed in their marketing as 6K, and that figure will show on a multimeter, so it’s all good right? The pickup will have around half as much copper (sold by weight) and less power than a typical high-end pickup. The result is not a pleasing one, and it’s one of the many reasons why we upgrade a lot of pickups.

There are about one hundred other reasons DC Resistance is misleading, and I could fill a book with them! I think Bill Lawrence had a better idea stating inductance values, it was a better indicator of power output, though there are always difficulties in quoting figures without industry consensus across different manufacturers of different pickups.

We don't wind to meet DCR figures. We talk with the customer about the types of guitar and amp they have, the material they play, the kind of tones and performance they hope to achieve from their gear, then work up a spec on the entire pickup, not just the coil, to achieve that sound.

If you would like to know about JJ's Guitar Pickups DCR or output levels, let's talk about it! Please get in touch!

Posted 01 September 2023