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Guitar Repair, Restoration and Guitar making - A Guitar Player Resource

A website dedicated to helping guitar players of every level learn more about their guitar, caring for their guitar, what to do when their guitar needs repair work and a shed light on what a professional luthier does when the guitar hits the workbench.  While some situations are easily remedied by simple adjustments a professional luthier knows best how to optimize your favorite guitar.

Blues Junior Comparison

The blog has been dormant as fall gave way to winter but plenty has been has been happening behind the scenes.  A few weeks ago a little time was set aside to try out a Zoom H6 recorder.  A simple recording set up enveloped one of my workbenches involving both Fender Blues Junior amps.  I used two Shure SM57 microphones and a Morley A/B/Y switch to quickly compare both amps.  The SM57's were set about 1" away from each grill slightly off-center to the speaker and angled slightly towards the cone.  The amplifier volumes hovered around 95 decibels monitored with the Decibel 10th app for iPhone.

Decibel 10th is a simple app for iPhone which helped get a sense for how loud the amplifiers were.

Decibel 10th is a simple app for iPhone which helped get a sense for how loud the amplifiers were.

Both of Blues Junior amps are early "green board" versions and were first set to match each other with flat tone controls (all set at 6 out of 12 on the dials) with volume and master controls set to "5" and the reverb also at "6".  The tweed Blues Junior is one with the BillM mods so the presence and sparkle controls were first set half way on the control or equivalent of about "6" of 12.

The guitar used was a Fender Stratocaster made in Mexico with stock pickups.  This particular guitar is generally near the workbench and I didn't want to use something with high end or custom pickups.  When listening to the following samples it might be worthwhile grabbing some headphones instead of standard computer or laptop speakers.  Headphones would certainly be better than listening with just a cell phone speaker for the mobile visitors.

Here are the controls of both amplifiers on the first set of samples:

Setting #1 - Stock Fender Blues Junior with green circuit board.

Setting #1 - Stock Fender Blues Junior with green circuit board.

Setting #1 - Modified Fender Blues Junior with green circuit board.  The two additional knobs are the sparkle control and presence control.

There are four parts to this audio clip with a short pause between each part.

1. Stock amp - bridge and middle pickups
2. Modified amp - bridge and middle pickups
3. Stock amp - neck and middle pickups
4. Modified amp - neck and middle pickups

After playing a little while bouncing between the two amplifiers I decided to contour both amps until I liked the sound.  I was no longer worried about both amps being dialed in the same but rather, I wanted to get them each sounding "good" to me and then compare them to each other.

Here are the controls of both amplifiers contoured to taste:

Setting #2 - Without changing the volume, master or reverb the tone stack was adjusted until the amp sounded more appealing.

Setting #2 - The presence and sparkle control were turned up to about three quarters of their maximum value and the tone stack had each control turned up slightly.

There are four parts to this audio clip with a short pause between each part.

1. Stock amp - bridge and middle pickups
2. Modified amp - bridge and middle pickups
3. Stock amp - neck and middle pickups
4. Modified amp - neck and middle pickups

After noodling on the guitar with both amps contoured a little bit the final tweaks were done to try and emphasize preamp distortion without adding volume so the volumes were turned to "10" and the master down to "2".

Here are the settings for the final round of comparisons:

Setting #3 - Stock Fender Blues Junior

Setting #3 - Modified Fender Blues Junior

There are five parts to this audio clip with a short pause between each part.

  1. Stock amp - bridge and middle pickups
  2. Modified amp - bridge and middle pickups
  3. Stock amp - bridge and middle pickups
  4. Modified amp - bridge and middle pickups
  5. Modified amp - neck and middle pickups

It's probably worth mentioning when I set up to record there was never a thought of sharing it in any form.  Once it was recorded on the Zoom H6 it was loaded into Garage Band and edited down making notes of the different clips.  There has been no additional processing of the sounds with compression, equalization, limiters or volume changes.  While over the years I've done a fair amount of studio recording someone else was at the wheel getting the tones to tape or digital formats.  There really is no performance involved with these clips instead it's just me noodling around on the guitar one evening...essentially making noise.

Let me wrap things up with a couple of my own impressions.

  • These audio clips do seem to convey the differences in sound quality of these two amplifiers. 
  • Another thing you may have noticed is the difference in reverb even though they were both set to "6".  Within the different BillM mods for the Blues Junior he includes a modification to the reverb circuit.  Both amplifiers used in this comparison had their stock reverb tanks and the difference is all about the modifications designed and sold by BillM Audio. 

If you haven't had a chance, check out my earlier blog post (HERE) detailing which modifications I made to the tweed Blues Junior.

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