MXR Noise Gate, now with more flatness.

Did a mod to my MXR noise gate tonight.

I’ve not owned a noise gate since the early 90s in my wannabe Helmet days.

I picked up a 1980 MXR Noise Gate Line driver for $40 on ebay about a month ago. Neat. I figure if I don’t like it, I can put it up with a $75 BIN and make a profit.

I plugged it in at full volume. It works great! Much better than my old DOD gate. I was quite surprised.

The “Line Driver” part is hilarious. The final part of the circuit is a 741 opamp buffer. There is an XLR out on the side. However, the XRL hot is just hooked to the 1/4″ out hot connection. The XLR minus and ground are just connected together. That’s just silly. It’s just a high current, unbalanced signal.

It seems to lose a bit of low end and level, but it doesn’t sound bad; nothing you couldn’t EQ out. The bypass isn’t a bypass in the traditional sense. When you turn the pedal off, that just grounds out a part of the gating circuit so that the gate stays full open.

Anyway, I’m surprised by how nice it sounds! but tonight I decided to change a couple caps to see if it would improve the sound.

Replaced the caps noted above with .1uf. ┬áIt lets more low end through than it previously did. I didn’t really run the numbers, but it does sound a little better

I now actually like the buffered signal (with the pedal on or off) more than a true bypassed signal.


Who needs more iron? I do!

I got this Traynor head from my friend Jeremy of the bands Charmless and Truxton. It had been tweaked and un-tweaked, and just generally seemed a bit rough and needing love. I bought it with one idea in mind; use it as a platform for my ultimate high-gain amp.

Earlier in this log you can see my previous mods. I removed the presence control, I turned that knob into a master volume, I cascaded the gain stages, and I left two gain knobs, allowing me to control the gain level leaving both the first and second gain stages. Essentially, I took a JCM800 circuit, hot-rodded it a bit, and corrected all the stuff I didn’t like about it. The result is a crunchy amp with more gain and a much wider range of tones.

During all this work, I noticed that the output transformer was a bit small. Okay, it was more than a bit small; it was smaller than the stock output transformer on my Pro Reverb, which can handle roughly 35 watts. I thought maybe this was the reason the head seemed not very loud, and to squish out earlier than expected on the master volume knob. Many people would like this aspect, since it was a little quieter when saturating. I play in a band with Chris Bolig on drums, who is, whithout a doubt, the loudest drummer I have ever seen, let alone had as a band-mate.

I was hoping a new transformer would give the amp a bit more volume and force. By force I mean that kind of hard to define “whump” that ones feels when say a low palm muted chord is played on an amp with high headroom. Plus, the traynor only had an 8 ohm out. Having 4, 8, and 16 ohm taps would be a great improvement for me. I noticed that Triode Electronics has a very reasonably prices 50 watt Marshall replacement transformer. I was already ordering a tranny to fix my pal Scott’s Alamo amp. What the hell, I grabbed the Marshall tranny.

Traynor Transformer Replacement

Today I finally found a big block of unused time. I decided to swap the transformers, and record the before and after.

Here is the mic setup.
Traynor Transformer Replacement

And here was how I set the knobs.
Traynor Transformer Replacement

And here is how it sounds.
Old Transformer MP3

The first thing I had to do was to pull the chassis. On a Traynor, this is INCREDIBLY easy. Remove four big machined screws, and the top of the amp comes off, exposing the guts. Then there are two more machine screws on each side. With the second set of four removed, the chassis comes out effortlessly. It is so much easier than pretty much every other amp.

So within about 10 or 15 minutes I had the chassis out and the old transformer removed. For a comparison, here is the old transformer next to the new one.
Traynor Transformer Replacement

Since the new transformer is significantly bigger, I had to drill holes in the chassis. I would normally shy away from this, but the chassis already had a number of extra holes. This just made me feel better about it. The amp is way past ever doing an immaculate restoration job. Plus, it’s one of the least desirable years of the YBA-1.

Here is the new transformer being mocked up.
Traynor Transformer Replacement

And here are the new holes I drilled, as shown by my pointing tools.
Traynor Transformer Replacement

The hardest part followed. I had to fit all the new wires into the amp through the one access hole, and then under the circuit board. Plus, the transformer was heavy and it had to be held in place without yet being mounted to do this. I devised a system of setting the chassis vertically and propping the new transformer close to its final position while gently weaving the wires through the inside of the amp. I was a bit too occupied to take photos. I got everything in, bolted the chassis, routed everything, trimmed the wires, and soldered everything in.

Then I had to drill the final hole. There were two speaker outs on the amps already. I had three taps for the impedance options. Rather than putting in a switch, I just added a third speaker jack. Here is the end result.

Traynor Transformer Replacement

And here are the jacks from the inside.
Traynor Transformer Replacement

So it was all wired up, labeled. The only thing to do now was to put the tubes back in and make sure it worked. I set all the knobs back to where they were, and recorded the same audio bit.
New Transformer MP3

The result: there was a slight difference, but not a ton. However, this was only at that specific volume and gain setting. One thing that does not translate is that if you’re in the room, there is a definite feeling of pushing a bit more air that wasn’t there before. Also, when cranking it up, the power saturation starts later, and the amp is just a touch louder. The low frequencies are a bit more defined, meaning they have more transient response and don’t squish out as much.

For me, I call this a success.

Tech details: Signal chain.

Electrical Guitar Company # 368 – bridge pickup.
4-12 with Mesa Black Shadow miked.
57 about 4 inches from the grill.
Metric Halo Mobile IO
Recorded at 44.1/24 then converted to a 192kbps MP3 in Logic

Larger photos here.