Cure Thoughts

Things I’ve been thinking about since seeing the Cure last night.

1. No mics on the amps. I think they have Palmer load boxes. This was fascinating to me.

2. A lot of people like the Cure. I think they are just kind of one of those universal bands now. Still, I don’t understand why. These were not cheap tickets, yet they sold out the bowl three nights. At the same time, it seems like I overheard half the crowd complaining that they don’t know most of the songs. Who pays $150 to see a show if they only know three songs by the band?

3. Reeves had a guitar tech and was getting new guitars handed to him every couple songs. Robert had his four/five guitars on stands behind him and would just swap them out himself. I don’t even remember seeing him tune. He needed no techs.

4. Robert has a couple Supro amps and a couple Roland Cube amps. My guess would be cubes for the Bass VI and Supros for guitar, but I could also see it being the reverse. Dude is such a gear weirdo.

5. The t-shirt designs were all pretty terrible. I got the most black and least offensive one. Still, I can’t imagine that the band really had much to do with these designs. They all seemed so by-the-numbers.

6. No wireless. Everyone had cables. In fact the whole stage setup was not overly complex. The lighting and video was set dressing, no all enveloping like most tours nowadays. It was more like an updated 80s show. Still, no wireless! I can’t remember the last time I’d seen a no-wireless stadium/amphitheater show.

7. Robert messed up Fascination Street. He went into the little Cmin6 descending bit 4 or 8 measures too early. Because of this, the whole band seemed to second guess where they were in the intro. This delighted me. It was so human and great to have an imperfect live experience. I loved it!

8. Some of the old songs got “rocked out”. “A Forest” just sound weird with big, warm sounding guitars and a big kick-snare AC/DC beat. The original recording is so cold and stiff and willfully minimal and restrained. It wasn’t bad, but I feel some songs lost their spirit or intent.

9. The Robert Smith signature guitar looks terrible on anyone but Robert Smith. It looks fine on him, but on anyone else… ridiculous. Conversely, the Reeves Gabrels Spacehawk guitar looks good on anyone.

10. As for the concert overall.. there were a lot of songs, but the time FLEW by. Claudia commented that it seemed to go by in the same amount of time as one of my 22 minute punk rock shows 😉 Overall, it was a totally delightful and emotional experience.

Explain Yourself (and your pedalboards), Ben Adrian

I recently cut my pedalboard into two pedalboards.  Previously, I used the size of my pedalboard as my upper limit.  However, I had grown frustrated by ergonomics, not size limitations.  That frustration resulted in this…Image

Every important switch is now on the bottoms or outer edges of the boards.  There is no more stepping over other pedals, which usually led to my clumsy feet changing settings.  Also, it got the volume and the expression pedals on the board.  Before, they had to be set up on the floor.  Finally, it’s nice having the M9 on a separate board, because there are many times when I can just use that and it’s enough.

Some of you may be asking, “why that order?”  It doesn’t seem all that unusual to me, but everything is placed as such for a variety of reasons. 

First off, the Fuzz is first.  It’s a fuzz face variant, and it interacts with the direct connection of the guitar.  When I turn down the volume all the way, I get AM radio.  It’s rad.  I would RATHER have the fuzz after the distortion, but it really does sounds much better first.

The Hotcake is next.  It’s set for just a slight overdrive and boost.  The biggest reason why this is second is because the pedal has an awesome buffer built in.  It’s not true bypass, and that’s great for me.  I need the high quality buffer right there.

The hot cake feeds the volume pedal and tuner in.  I’m the kind of nerd that notices signal losses and tone changes with passive volume pedals.  I would never use the tuner out as well.  However, since the volume and tuner are post buffer, they sound and work great.

Following the volume is the Boss DM-2 Analog delay.  This gets the most questions when nerds bother to notice.  The tradition role is to put delays at the end.  I do that, as I’ll explain later.  However, I began running my analog delays before distortion many years ago.  This accentuated the analog qualities of teh delay when run into a distortion pedal or a distorted amp.  The traditional tape echo sound is the echo placed in front of an amp on the edge.  Plus, when playing single note runs, the compression that comes with the distortion will bring up the echo level until I hit the next note.  The new note will cause the echos to be ducked and squish down in volume.  It works great.

The Ben Adrian Bunnydrive is next.  This is the Distortion that I make, and it’s set for medium gain.  Nothing fancy; just good, reliable tone.

The Freeze is pretty much only used when I play solo guitar.  It’s a ton of fun, but being last also allows me to pull it off the board easily if I know I won’t need it for a gig.  In fact, I could probably pull it off and replace it with a digital delay for certain gigs, and just leave M( at home.  Of course, I’d need to be using an amp with reverb.

The M9 now sits alone on its own board.  This gives me a complicated and awesome digital delay and looping setup, with the expression pedal altering the delay feedback.  I also use this for big, fake reverbs, or for a more subtle verb when I’m using a non-reverb amp.  I’ll also pull in the random phaser or chorus from time to time, and I’ll use it for a lot of looping duties in solo performance.

The whole thing seems like a large and unwieldy setup, and it can look a bit messy, but the end result is two useable, separate units that can Voltron into one big unit that is equivalent to my old big board.

Now excuse me while I plug my Tele straight into my Pro Reverb.

Weekend Log

Finished Trey P’s Bunnydrive.

Assembled and tested Mike D’s (no not that Mike D.) “mod-wah board” for experimentation on an upcoming filter pedal design.

Brainstormed on Steve V’s “EXPLODE” pedal, a crazy, over the top fuzz-stortion.

Recapped Jason P’s V-4.

Diagnosed Jason P’s YCV-50. Ordered the part. Traynor/Yorkville rules!

Restrung the EGC.

I haven’t written here in a while. The projects have been more mundane and less experimental. last night I had a nice little catch up.

1. “Repaired” an old Digitech dual pedal Chorus/Flanger.
2. Debugged a broken Guv’nor pedal. I have to order a part.
3. Fixed an old benadrian pedal with a broken LED for Howie.
4. Reassembled Jeremy’s Jackson head for sale.

I feel like I did more. Meh.

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.  It 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.

Cheers!

The Pro Reverb distortion saga

So about two weeks ago I practiced and played a show. I noticed my new guitar level was causing an ugly distortion in my amp. I decided to ask some friends on a message board about my ideas to reduce gain by just a touch. This took me for a silly but informative ride. Warning: this could be a long post. Grab a snack.

Feb 25th

My new guitar rules. The one thing that’s throwing me is that it’s a lot louder than my previous man guitar. When I plug straight into the amp, or run it with no pedals, it still distorts too much for my liking. I can’t just turn the amp volume down, because it’s distorting the first gain stage, which comes before the volume knob in the amp’s circuitry. The amp is a pro reverb.

The easiest answer is volume pedal. However, I’d never use it for adjusting volume creatively. Plus, I’d like to avoid adding series resistance, avoid removing resistance to ground, as well as avoid a huge pedal. So I’ve come up with a bunch of overly complicated solutions.

1. Plugging into input 2. Tried it last night. Too much loss, too mushy, too much resistance to ground is removed.

1A. Replace the 68k resistor on input 2 to a higher value, like 250k. Plugging into 2 gives me a bit less of a pad than before, but plugging into 1 gives essentially the same sound. Might work.

1B. Install a pot in the hole of input 2 to replace the 1M resistor to ground, making the input impedance continuously variable.
Would probably work, but kind of silly.

2. Tiny unity buffer box with the ability to cut level, placed at the front or back of the pedal tray. Pull down the volume of the guitar in an active fashion.
Would definitely work, but another powered device to worry about.

3. Change the cathode resistor on the first gain stage from 1.5k to 2.2k, 2.7k, or 3.3k. It will give more headroom and less level out of the first stage. I just turn up a pinch to make up the volume lost on my other guitars.
I like this the most, as I like custom tailoring my amp, but is it overkill?

Thoughts? Other ideas?

Twenty four hours later I posted.

4. solid state rectifier plug in. higher voltage might increase headroom on first gain stage
hmmm.

I was getting pretty confident in my assessment. Oh, how I was so wrong.

Erik Miller of Euthymia Electronics posted this.

You should figure out exactly which amplification stage is causing the problem. My guess is that you’ll find it further down the chain. There is a LOT of headroom in that first stage; you have to hit it really hard before it clips.

You’re welcome to bring the amp over and use one of my ‘scopes if you like.

I was too curious to wait to head over to Erik’s shop, so I did a bit more testing myself.

Okay, Erik is right.

I did the trick where I hook up a coupling cap though a couple jumpers and run various points of the amp out to another amp.

So I pulled the power tubes and ran various points of the amp into a SS power amp and cab. After the first gain stage, clean, after second gain stage, clean, after reverb recovery, clean. Then, after the phase inverter, it’s crunchy. Also, though, there is this hard clipping distortion that happens where there is enough level. It hits a certain point and it sounds like a shitty fuzz. Once it gets under a certain level, the distortion just stops. I hooked it up to the both plates of the phase inverter tube, and it’s a bit worse on the side with the 100k plate load resistor, and a little less on the side with the 82k plate load.

So, I tried a different 12AT7. Still there.
I tried a third 12AT7. Still there.
I swapped the .1 cap in the cathode section of the phase inverter. Still there.
I changed the 1M resistor on the non-input side of the PI and the 100k plate load resistor. Still there.
I changed the bias cap, because it was ancient and needed it. No help but I didn’t expect it.
I changed the .1uf coupling cap on the 100k side after the phase inverter, no change.

One thing I didn’t check was the filter cap that feeds that section. I gave it a full cap job about 5 years ago, did a visual inspection tonight, and prodded it with the chopstick, and it never seemed to add or reduce the distortion.

Things i didn’t get to check. The 82k plate load on half of the phase inverter. The 100 ohm, 22k, or 470 ohm resistors in the long tail section.

To be clear. I hook up to the spot on the board where the .001 coupling cap meets the wire that goes to the tube. No distortion, sounds great. I hook up to where pins 1 and 6 meet the board, distortion on both sides. Definitely not the tube.

Thoughts?

Finally I got over to Erik’s shop…

So Erik and I scoped my amp today.

We were getting some weird blocking distortion and oscillations, so we changed some coupling caps and the resistors on the grids of the power tube.

Here’s the funny part. After about 90 minutes of futzing with a signal generator into a load, I was playing the guitar through a speaker, and heard some bonus noise. We found out that the reverb return tube had a really dirty socket. We hit it with some deoxit and it cleaned it right up.

I was thinking though, I never got the distortion after the reverb send while testing. It was usually much quieter and less compressed when I was taking the line out post-reverb return. However, it was much louder and more squished when taking the post phase inverter line out. That was causing a vibration when the amp head was on top of my test amp, which must have been causing the rude noise earlier in the signal chain.

Anyway, thanks Erik; it was really neat putting the amp on the scope and checking it out!

Okay. I thought it was fixed. Here’s where it gets fun.

just spent a couple hours befuddled by my amp.

Here’s my amp.

When Erik and I left, he had put in new coupling caps between the phase inverter plates and the power tube grids. However, he left the leads very long on purpose. Since I had to pull them anyway to clean it up, I decided to do some more testing tonight. So I pulled the coupling caps and power tubes and did some more audio probe testing.

Remember the phase inverter is not connected to the power amp. Essentially, it’s just the preamp.

I hooked up the synth, held down a G with tape, and plugged it in to the amp. When I hooked the audio probe to the plates of the first three gain stages, I got clean signal or a natural mild overdrive. when I hooked up to the plates of the phase inverter, it sounds clean until the volume hits a point, and then it gets kind of a very hard clipped distortion. However, after a couple more numbers on the volume knob, the harsh distortion/static stops. Here’s the funny part. On the plate connected to the 82K plate load, it distorts heavily from about 7-9, but on the side with the 100k plate load resistor, it distorts from about 5-7. So the lower value plate loads is bleeding off more audio signal to ground through the filter cap, making me have to turn the volume higher to get the distortion.

Also, when I turn the volume up on the keyboard, then the distortion happens lower on the volume knob.

So the distortion is frequency dependent, as well as level dependent to something in the phase inverter circuit. However, once it goes past a certain level/voltage, the ugly static/distortion stops. Also, adjusting the tone controls will adjust when the distortion happens.

I wanted to simplify the circuit. I pulled out all the tubes except for the normal channel and the phase inverter. I still got the harsh distortion, and only on the phase inverter plates. Also, I found that if I hoo up to pin 7 grid of the phase inverter, I can hear a similar static. So whatever it is, it’s not on the pin 2 grid signal input, but I pick it up on the other grid of the PI. In addition, it seems in phase on both sides of the phase inverter. So whatever is causing the noise, it’s modulating the current through the PI in phase on both side, and is not coming in from previously in the circuit.

Since the distortion happens at different levels on each plate, and is in phase on both sides of the PI, it gets somewhat cancelled out when running through the power amp and output transformer. I hear the difference when running through the amp in normal operating mode.

I thought maybe there was a problem with the filter cap on the PI section. Perhaps at a certain voltage level it will get weird. I swapped the filter cap, and the problem did not change at all.

My next test is to pull all the tubes except for the PI, find a way to run a loud enough input signal into the grid, and check the output on the plates. I want to make sure it’s a defect in the PI circuit, and not multi-stage interaction.

I’ve heard stories about fender circuit boards becoming semi conductive, or flux on the board acting like a capacitor with other flux on the board. The board is 45 years old, and very warped. I can’t help but want to put a new board in and just prepare my amp for the next 45 years.

So I’m pretty stumped. I can’t help but think that it’s one bad part that fails at a certain frequency or ac voltage. Also, it could be some kind of low frequency oscillation that happens at a certain voltage/frequency, and then intermodulates the audio.

The other idea is to just pull and replace EVERYTHING in PI section (caps, resistors, socket wires, etc.) see if that fixes it. I’d clean the board when everything was pulled as well.

Meh.

And then tonight I have this little experience

onight I decided to try and fix my weirdo amp problem.

I hook my amp up like I had before, with the power tubes pulled and an audio probe hooked into a power amp from the phase inverter. I ran my keyboard into the amp to play the note that would fart out the phase inverter. Guess what? It works fine. I can NOT get the amp to get all weird on me. It was a little disconcerting, actually.

So I put the amp back together and fire it up. There is a loud hum and very low volume. I’m messing with knobs and I smell burning. I look in the back and the power tube closest to the rectifier is bright fucking red!

I turn it off, swap the power tubes, fire it up really quick, and the problem stays with the socket. Something must have happened with the bias supply. I take apart the amp again. I measure the bias. It seems to be fine. I put in my spare tubes. They’re running fine. I prod the new grid stopper and pop, tube goes crazy and the bias has cut out on that tube. Shit, I must have done a cold joint on the resistor.

I re-solder the resistor, and the tube is still ramping up, but there is -16v on the grid instead of -45 (correct) or 0 (the way it was wrong before when I almost had a Chernobyl. I swap the replacement tubes and now the problem follows the tube! I must have damaged my replacement tube while testing the bias. Balls. I put the original tubes in, and it works and sounds great. I put the amp back together and no meltdown. Hooray?

So, let’s see how long this lasts. It really sounds wonderful right now, though.

Did you make it through? I hate and love my amp. Cheers.