DigiTech RP155 - A Great Pedal

I'm a tone god wannabe with no budget. I look for all the answers when it comes to getting the right guitar sound. I have tube amps. I have essential stompboxes. I have the most recommended guitars for my budget. And yet I have not been able to get the sound I want. Lately I have listened to the modelling amps that have been coming out on the market and I've been impressed. The top-of-the-line Peavey Vyper sounds great to my ears. I couldn't just go and replace my amps to pick this one up.

 

Weeks ago I went to our clubhouse and watched a local band, the Rock and Roll Relics perform. I'm a groupie. This talented band has a setup I wish we had in the Clubsiders. The guitarist Gail always sounds like the guitar players she mimicks. I've spoken to her before about her setup and she always has an older Vox Valvetronics with a Vox Multi-effects Pedal. That made me think that perhaps the answer is to get a modelling multi-effects pedal to mimick the guitar sounds. My first choice was the Vox Tonelab ST but then the question was, "how am I going to afford to get one?"

 

Fortunately my boss gave me a bonus. But after the money was allocated to various things like a trip to Boston late this spring and a new cellphone, I was left with too little money for the Vox. I then started looking around. I found the DigiTech RP90 and up until the day I was buying it I dreamed of having it. There were two big disadvantages to this pedal: no USB interface and no fuzz pedal emulation. They were two caveats that I thought I was going to compromise with. But that day I discovered that the DigiTech RP155 was the same price and instead of compromising those caveats I had to compromise with the expression pedal. Looking at the jacks on the pedal, an expression pedal input was included. That's it. I was sold. I bought the RP155.

 

Well, now that I have bought the RP155 I have had some time to play with it. The bottom line is that this is the best thing I ever spent $100 for. I can get the tone I was looking for and I didn't need to adjust the amp to do it. That's important given that the Fender Champion 600 has only a volume control. The RP155 has a decent equalizer and five preset tone settings along with the ability to adjust bass, midrange, and treble level and frequency. I suggest creating the sounds you want and listening to them through your amp as opposed to using the canned presets. If I had gotten the RP90 I wouldn't be so dog-gonned pleased with this. With the USB interface you can use the X-Edit software available from DigiTech. It is available for Windows or Mac. This software makes it very easy to create the sound presets you want. The methods used to create the sounds from the pedal are confusing and require some learning time. Not so with the software. Everything's there and the flexibility is amazing.

 

The equalizer and the noise gate are key. The Lexicon reverb settings are also great. My Vox AC30 has tremolo that I want to utilize when we play shows but I won't lug this anchor to practice. The tremolo works great on the RP155. The distortion effects sound very accurate to me as well as the different amp and cabinet settings. I have not tried to use this to work with GarageBand or any other recording tool. I am still learning how to take advantage of the twenty second looper. I think it should be a thirty second looper but I'm just learning how to use one so for me this is fine. I thought the two-pedal tap for the bypass would be an issue but both pedals could be tapped with one foot. The bypass sounds like a true-bypass but since I want to control tone I will most likely store rhythm/lead settings adjacent to each other. Fifty new settings can be stored which is more than enough because the fancier effects are less likely to be used. I do like playing with the Whammy effect and the delay effects sound really good.

 

This is really a partial review but I am quite impressed with this pedal. It feels like it can be abused but since it doesn't use real stompbox switches, I'd be careful. I am going to get an expression pedal soon. I will take this to practice and to gigs and will get comfortable with the looper before I re-review this pedal in the future. As for right now, I highly recommend this if you are not a purist with a keen ear for tone god perfection. That will cost you a lot more money.

Telecaster Four-Way Switch Mod

It took me very little time to go for the mod. I was hoping that wiring the pickups in series would give me the crunch sound that the humbuckers on my Les Paul give me. I ordered the Tritan four-way switch from Guitar Parts Resource. Warning to those who choose to buy this lever switch - the slot on the plate is not long enough. I had to use my Dremel tool to lengthen the slot so that the switch could go all the way to position one.

I used the wiring diagram from Rothstein Guitars. Both pickups normally have the negative leads grounded but one of the negative leads has to go to the switch. The neck pickup seems logical to me because the metal shield is grounded. The Rothstein mod instructs you to disconnect the wire on the shield going to the negative lead on the pickup and adding a wire to the shield to run to the back of the volume pot. The only problem I had wiring was starting it with the switch backwards. I had to study the wiring diagram and the switch to find the common pins. Other than that the diagram was easy to follow. I tested the wiring before I mounted the switch to the plate. Everything was fine.

I recommend plugging a cord into the output jack and testing the resistance while switching through the positions. The bridge pickup has a higher resistance than the neck. Wiring them in parallel will read less than half of the bridge pickup and more than half of the neck pickup. Wiring them in series will read the sum of both pickups.

I mounted the switch and put the guitar back together, plugged it into my amp and was disappointed with  positions one and two sounding the same. I did the resistance check and found position one measured what position two did (both pickups in parallel.) I lifted the plate and discovered the switch could not go all the way to position one. Fortunately I had a Dremel tool and with a little labor and a couple of broken wafer discs I got the switch to work. Looking closely at the picture above, the plate was nicked in the process. Consider it the start of my relicing project. :)

Fender also makes a four-way switch at over twice the price of the Tritan. I could not tell you if the switch or the slot is the problem but other than this problem the Tritan works fine. I have one more mod I want to implement. It requires a push-pull switch/potentiometer and a .001uF capacitor. This is my own design for adding a "cocked wah" sound usually done to Fender Esquires (Telecasters with just the bridge pickup.) Esquires have the same three-way switch that Telecasters do but it is used to modify the tone. I will post the results in the future.

Testing the mod, both pickups in series did not give me the humbucker crunch but did give me a stronger midrange sound. It does add to the versatility of the guitar and sitting at switch position three I can play rhythm and go to position four for leads. I'm not set up to provide a sound demo. I hope to in the future.

New Guitar - A Review

Time flies and I've stayed away from my blog despite a lot of rants I wanted to post. I probably will post about the shooter who shot Congresswoman Giffords but for now I will write about a guitar I bought after Christmas.

The guitar is a Fender Squier Classic Vibe '50s Telecaster.

That's not a great picture but it is a great guitar. I can't afford to buy my dream guitar (a Gibson Custom Shop VOS 1959 Les Paul Reissue, which can be bought for < $6000) so I look for good guitars for a heck of a lot cheaper. Before I go on, I can understand if a non-musician says to me "why if you don't make money playing the guitar?" but a musician asked me that question when he knows the difference between a cheap instrument and an expensive one. I don't ever care if I make money playing the guitar, that guitar is my dream guitar. Back to the Fender.

I decided on this guitar based on word-of-mouth. I visit the TDPRI Telecaster Forum regularly and I listen to people at Guitar Center or wherever I go. This guitar was the most talked about because for the price, people were saving from buying the more expensive Made in America Fenders after playing these. I needed a guitar to perform with that would allow me to play standard tuning. Since I started playing guitar again I played with a tuning that reflects my banjo skills (Bb, F, C, G, B, D) and due to string gauges (.012 - .070) I couldn't just retune to standard tuning much less spend the time doing so at a gig. When it was time to look I decided to get the Squier CV50.

Back in 1993 I bought a Fender '52 Reissue Telecaster and owned it for twelve years. I didn't cherish it - I thought it didn't have great pickups and acoustically it didn't resonate well. I thought all telecasters were like this. I had it until 2005 when I totally stopped playing guitar. I actually sold it for more than I bought it but that is how guitars value. I don't see this Chinese-made lower end guitar doing the same but this guitar may be the exception. So my review of this guitar will be based on comparison to the '52 RI. Overall, it is the best out-of-the-box guitar I've bought since 2008 and possibly the best ever.

First, the plusses:

The fretwork on this guitar is better than any guitar I've ever owned. The frets are dressed perfectly and were leveled. Guitars made at this level will usually sacrifice this much quality in the manufacturing process.

The intonation and neck bow was perfect out-of-the-box. I just had to lower the strings at the bridge.

The acoustic resonance was remarkably well. There must be something to pine and maple as the choice woods for this guitar. The ash/maple on the '52 RI didn't sound this good.

The bridge pickup is hot and tone-wise good. I can't compare it to boutique pickups but my other electric pickups don't sound this good and the '52 RI didn't either. The magnets are Alnico IIIs.

The neck pickup is not as hot but also sounds good. I must say that the resonance of the guitar is probably adding to the pickups to make them sound good. I will not be replacing the pickups.

The volume and tone potentiometers are made by Alpha and have a great feel and quality.

The tuners are solid. I've had to buy tuners for Chinese made guitars before.

The nut is synthetic bone and was cut perfectly at the factory.

Now the minuses:

The pickguard looks cheap. Being wintertime I had a pickguard static issue. I fixed it by placing a drier sheet under the pickguard. I can't blame the pickguard for that but it did make me notice how much better my other guitars' pickguards looked and felt. The '52 RI had a bakelite pickguard, which I find superior to all plastic pickguards.

The saddles on the bridge are low quality. The screws to adjust the height are too tall and can grab one's hand. With the good intonation I won't bother to replace it.

The bridge pickup route is exposed slightly on the side of the bridge plate. This is me being nit picky but I never noticed it on the '52 RI.

These minuses are not major. I will replace the pickguard only because I want a white one.

Finally, where I have no opinion (yet):

The input jack and cup - People have had problems with flimsy jacks and cups. They are buying Switchcraft jacks and Electrosockets to replace them. I have not had a problem yet. I will consider this in the future if necessary.

The switch - I am replacing it with a four-way switch because I'm adding a mod (surprise). The switch is fine.

Knobs - they're fine.

The only other thing I will say is that these guitars only come in the cream color with black pickguard. The cream varies by guitar from white, to yellow, to slightly green. Mine is more yellow and I like it a lot.

Keep in mind that guitars vary in quality off the assembly line. In America flaws are caught more often than in Asian countries. One person complained that the frets were really bad. Others have had pickups fail. Don't judge this guitar by the words of a few because a vast majority rave over this guitar. Replace bad ones with another CV50.

The mod I mentioned will be posted in the future.

Tube Amp Project - 12/24

Wow, it's been a while since I posted anything on here. I did get the parts for my mods. I changed my approach a little but I must say I'm satisfied with the results.

I'll start with the first preamp stage. I had taken out the cathode bypass capacitor as per a recommendation but I noticed a loss in gain. I discovered why when I studied tube amp design. The capacitor has no effect on the DC circuit so the cathode bias primarily controlled by the cathode resistor is unchanged. But for the guitar signal's AC the capacitor makes it act like the cathode is connected directly to ground so that the gain will not be limited by the cathode resistor. I took the direction that I had been recommended in one of the websites I visited and changed the plate resistor, cathode resistor and placed a new cathode bypass capacitor in the first preamp circuit. The plate resistor (R8) was 100k ohms 1/2 watt. I replaced it with a 1 watt 220k resistor. The cathode resistor (R2) was 1.5k 1/4 watt. I replaced it with a 1/2 watt 3k resistor. By the way, I did not check my bias current which could be bad. I had to stray a little bit for the recommended resistor values. This could effect the life of the tube. The original bypass capacitor was a 22uF/25V electrolytic. I read that such a high capacitance provides a flat gain throughout the guitar's entire frequency range. The replacement is a .68uF/630V Solen "Fast" Cap. The lower capacitance provides a bass rolloff that was recommended. The entire circuit change was to change the shape of the guitar signal away from the stock Fender shape. If that is an issue don't do it. But don't cut out C3 unless you want lower gain out of the first preamp stage.

The tone stack after the first preamp was the big gain killer. I had been recommended bypassing the entire circuit with a 0.22uF capacitor so I bought a switch to choose either circuit. I opted instead to keep the tone stack in place and just boost the gain by doubling the value of the midrange resistor (R19). I replaced a 15k 1/4 watt resistor with a 31k 1/2 watt resistor. Also, I replaced the treble capacitor (250pF) with a silver mica capacitor of the same value. I was recommended certain types of capacitors for improving tone. I also read though that Fenders used ceramic caps in their tone stacks. I can't recall if the original was ceramic but since I already took out the Fender "tone" it didn't matter. Since I was no longer bypassing the tone stack I took my new orange drop 0.22uF capacitor and replaced the second preamp output capacitor with it for improved tone. By doubling the resistance of R19 I got a noticeable gain boost and I like how the distortion sounds at the higher volume. Success.

This will conclude my guitar amp project for a while. I'm still up in the air about the speaker. Lots of people swear by replacing it. I don't know if I want to deal with a 6 inch speaker or just plug a 12 inch speaker in a cabinet into the speaker jack in the amp. Anyway I'm happy for now.

Note: Sharing this information was not to tell you step by step what to do to make better sounds out of a Fender Champion 600 amp. It is only telling you what I did. The risks taken by me to make these these mods are my responsibility. Doing any mods to your own amp is your responsibility. If your amp is under warranty it will not be afterwards. I was an electronics technician for seventeen years. Tube amplifiers use higher voltages than what comes out of your wall. Capacitors charge up and discharging a cap with your body can be dangerous. A proper soldering iron and some soldering experience is necessary to keep from damaging the printed circuit board. Don't look at what I did to be any better than the others who modified their amps. And so on...

Tube Amp Project - 12/7

It's been a while since I last updated this project. I've made two significant changes and changed my mind on an earlier change. I got compliments on my tone from a bandmate but there are still changes to be made.

I ordered new tubes from The Tube Store and while I was waiting for them I found some older tubes in my stock of parts I never seem to throw away. The one 12AX7 tube was never used but made in China. I didn't try it at first because I assumed the current tube was from China. The second tube I found was a General Electric I forgot about. I was excited about a big brand name tube so I pulled the 12AX7 out of the amp. Surprise! It was a Sovtek tube, Fender's brand of choice. I put the GE tube in and found out why I didn't use it before.

Tubes are mechanical devices. Their sound comes from physical plates. These plates can vibrate so precautions are taken during construction. When I cranked up the amp I got an awful audible rattle from the tube. The amp worked but the rattle made the tube useless. I'll keep the box.

So I decided to throw the Chinese tube in there. I noticed how quiet the amp was when I wasn't playing a note. But I also noticed lower gain. I was impressed though and will keep the tube. In the meantime I threw the Russian Sovtek back in the amp and then I noticed that the gain was lower too. I was starting to think another mod actually lowered the gain.

The tubes came in last Thursday and I was too busy to really evaluate them. The 12AX7 is made by JJ and they have a really good reputation. The 6V6 is from Tung-Sol and it was highly recommended. I was happy to notice that the hum levels lowered and the tone was brilliant. The Tung-Sol replaced a Chinese 6V6. I couldn't be happier with this power tube. The gain however was still down and so I did some research. Going back to the removal of the C3 capacitor, that is something I should not have done.

I spent the weekend researching modification choices and discovered a tone changing set of part replacements that I am going to do. It will replace C3 with this mod and should keep out harsh lows and provide more gain. Instead of adding a three-way switch I am doing a tone stack bypass switch instead. That should help fix the problem I'm having with single coil pickups. My Epiphone Les Paul's humbuckers are sweet sounding but the pickups on my Strat copy are weak. The tone stack bypass will boost the single coil pickup and hopefully give me a true "Champ" sound.

The greatest sound change came from removing the grill cloth from in front of the speaker! I read a forum where everyone was recommending it. I could see why after I took it off - it was a pice of microfiber cloth that looked like it should have been on upholstery. The cloth was too restricting and the treble boost was enormous after I took it off. I had some screen material so I doubled it up and placed it in front of the speaker. I'll have to take pictures.

I hope to have the complete mod finished next week. I will take some pictures. Speaker replacement is still up in the air but as of right now I doubt that I will replace it. The isolation box is up in the air since I've discovered an attenuator that might be easier to implement. My band played last Saturday and I was very pleased with my tone. This Fender Champion 600 reissue was a great choice for the project.

Tube Amp Project

Why am I making modifications to my tube amp? I think history has something to do with it. I consider the tone of an electric guitar's sound to be more important if one isn't a virtuoso rock guitarist and just as important if one is a virtuoso rock guitarist. For me it's the former. The truth is that I'm quite unhappy with the sound I'm getting out of my amps. I didn't think about it until lately when I hit my overdrive pedal to play during an instrumental break in a song my band was playing. It was a practice session and while no one complained, I was frustrated with what I heard. I traded in that amp as part of buying my Fender Champion 600.

My Vox AC30 is a great amp but I can't play it loud. I won't give up that amp but right now I'm focusing on the little five watt amp I've discussed before. The Champion 600 is sort of a reissue of the original released in 1949. Back then nobody knew what electric guitars were supposed to sound like. The electric guitar was first produced in the 1930s and Leo Fender was producing electric lap steel guitars with amps since the mid forties. Amplifiers were designed from the RCA handbooks that many amp builders received at that time. The Champion 600 was designed for students but some of the best rock and roll guitar songs ever came from the output of those amps.

This reissue is not really a reissue. The original 5B1 circuit has been replaced by a current one. Never mess with perfection and always keep it simple. Fender did not do that. The original preamp circuit had no cathode bias capacitor. A tone stack was nowhere to be found. The negative feedback circuit didn't connect to the cathode of the preamp. These are in the current amp and while I think the intention was to keep the power tube from distorting at too low a volume, those circuits affected the tone that the original had.

I took a chance buying this amp but I knew the original circuits were easy to modify. It paid off with the amount of information I found online. I've found kits that cost almost twice as much as the amp. I found mods that cost nothing to implement. I have to stay in the middle of the road. Since the last time I wrote about this I've found other mods that might be as effective and easier to make.

I've made two modifications so far that have cost me no money. The biggest difference came when I cut out the negative feedback circuit. I'm a former technician, not an engineer, but I have a hunch as to why this was there. The original amp had a tube rectifier. The rectifier is made up of two or four diodes that convert the AC electricity from the electric company to DC electricity. A tube rectifier was two diodes. The current amp has four solid state diodes wired as a bridge rectifier. The bridge rectifier is better than a tube because current can change the characteristics of the tube. In amplifiers, excess current from overdriving the tubes cause the rectifier tube to "hesitate" providing the current. The result is a compression that can be heard. This added to the tone acceptably and I believe that by using the output to the speaker and feeding back to the cathode bias circuit in the second preamp stage would achieve a similar affect. I don't know but I found that the sound I got when I cut out the circuit was better.

The second modification I made was taking out the cathode bias capacitor in the first preamp stage. The verdict is still out on this mod. I haven't noticed a difference yet.

I have decided not to break the tone stack. Instead, I will just deal with the midrange resistor. I was going to replace it with a resistor twice its value. Now instead, I want to place a three-way switch to the console that will change the resistor's value to two and three times the original value. I also want to replace the tone stack capacitors with better ones of the same value. These capacitors can be bought at The Tube Store. So I think one order is necessary to be made along with ordering the replacement tubes for the amp, my biggest mod.

I'm not convinced of replacing the speaker yet. I have a better idea: I will buy a better speaker for my isolation box and decide then what the difference is.

This is more detailed than the previous mention. I will report back soon with an updated report.

(Update 11/28/2010 6:27AM - I found out that Blackface Fender Champs had the negative feedback to the cathode of the second preamp stage along with a tube rectifier. My hunch was wrong - Gary)

Song in my head: Baby I Go For You - The Blue Rondos