Crate V5 "MODS" will commence!

[cebreez]

Im getting parts in the mail as we speak. Soon I will begin my own experimenting on the Crate V5 in search of that illustrious tone and unobtainable headroom. Now by headroom I don't mean carrying this onstage at the auditorium and playing above the drummer and bass or even the tamborine in the back..;) Just want to clean it up. At full volume this thing should distort sweetly at lower decibels that won't bother the neighbors. A list of places to start:

1- A better preamp instead of the current preamp. Add back the gain knob from the V508.
2- A real tonestack. (Think concentric pots)
3- Move the volume to the correct position. Thanks to jim p and deafelectro for they have already done this.
4- REVERB (Belton I'm sure)
5- DI (Wishfull thinking I know, but just in case I like the sound so much I want to pipe it .... somewhere!)

Already replaced the speaker but looking for an even better one. Ordering Electro-Harmonix 12AX7, 12AT7 (for experimenting) and an EL84.
jim p says swapping out the 12ax7 for the 12at7 reduces the gain of the preamp so you regain some of the tone your losing. With my work on the preamp I'm implementing that actually would work out pretty darn nice. Maybe even the 12au7. Have to look at the specs again.

Will be posting pictures of my progress and all comments will be welcome. The results will be sent back to Crate so they can do it right the next time. (......Just Kidding.....)

[cebreez]

DELAYED AGAIN!! Still gathering parts. I did find a new place to order parts. http://www.tayda.com . Resistors pack of 10 for $.12. Or 100 for $1.20. Next payday I'm filling my parts cabinet with every resistor and capacitor available. No more piece mealing every project. May take a couple of paydays to get everything I want to keep in quantity but also cheaper and faster in the long run. Anyway still working out the details of the mods and am planing on trying some different configurations that may or may not work but I'll post a schematic of the working mods once I get into it.

OH!!! Does anybody know where to get there hands on a 10k linear dual concentric pot? Even if its salvaged vintage or even hand made. I need on bad!

[cheapgtrs]

I've been thinking of picking up one of the v5s so I'd love to see how this turns out. I'm a newb when it comes to amp modding but I'm about ready to get my toes wet. Good luck and keep us posted.

[cebreez]

Hey cheapgtrs! Yea I love the amp itself less the obvious tonal insufficiencies and the inability to get decent overdrive without getting too loud. Everybody talks about putting a couple of pedals in front of it but that negates the portability of it. I've yet to crack it back open but I have been working on some of the circuitry. I built a copy of the Sonic Maximizer called the "Bloviator" from http://www.madbeanpedals.com which I will install into the amp just behind the input jack the controls of which will occupy the input jacks current position and the tone controls position. Since the bloviator is basically a bass and treble booster and filter it will take the place of the tone control. Already experimented with this and it sounds phenomenal. Taking my cue from jimp I will be removing the opamp section and installing a 68K resistor at the input of the tube section. Then I will move the volume control to its correct place in the circuit.

All of this sounds great right up until I realized that I still would not have a gain control. Just a volume.... soooooo...... rework the stages or just add a rheostat on the speaker so I can overdrive the tubes naturally "one knob style" and still be able to turn the volume down.

Last but not least will be a much better 16ohm speaker...... probably a "Eminence Rajun Cajun"

Tayda Electronics (http://www.taydaelectronics.com)... Placed my first order from them 2 weeks ago. They are in Bangkok THAILAND so I was a little nervous about ordering from them. But let me say!! Ordering was easy, the parts are CHEAP "monetarily", shipping is CHEAP, and I got my parts in 5 days. I'm hooked. Just placed another order and got almost 4000 parts for under $20 and $8 shipping.

[stanley serrao]

I just bought myself a v5. All I did was change the tubes to Mesa Boogie tubes and put in a vintage jensen speaker with alnico magnet and I love it. The cleans are clean and warm and the overdrive drives. You don't have to do all that other stuff to get it sounding sweet!

[cebreez]

Mine already sounds good on the clean side. But to get the tonal range and specific overdrive I want I have to go a little deeper. Even with a tube change the opamp front end tends to be a little sterile and compressed. I need it to breathe better and have a better presence than it does now. I was going to leave the opamp but realized that replacing it with a better preamp circuit would be easier and give me better control. And I wanted a gain/volume setup to control the overdrive at lower volumes probably because that is just what I'm use to.

[Commodore 64]

Have you tried different opamps? Is it socketed? The TL072A is a 8-pin dual opAMP right? You could solder in a socket and try any number of opamp chips in there to see if there's any changes to your liking.

This post has a ton of info on what to change on the V5:

http://www.tdpri.com/forum/amp-central-station/145636-want-crate-v5-schematic.html#post1754695

[cebreez]

Thanks commodore64, I did think of that but opted for the lazy way out. Built a whole new circuit which I will put at the input as a preamp. Seriously... check this out: http://www.madbeanpedals.com/projects/Bloviator/docs/Bloviator.pdf
I took several people's advice and will disconnect the opamp circuit... install a 68k resistor at the input of the first tube stage then install this circuit between the input jack and the 68k resistor. Just trying to figure out the best was to get 9V to it. I've already built the circuit using their pcb for $9 just haven't had time to tear back into the Crate.

[cebreez]

Not meaning to get off topic.. I'm also almost done with their double-flush tremolo pedal circuit. Have a new box coming in this week to put it in. Their boards are great and easy to build. Even their "advanced" and "genius" boards are simple for anybody with decent soldering iron skills. I do though suggest a small tip 40W iron and a good magnifying glass.

[Commodore 64]

Just trying to figure out the best was to get 9V to it. I've already built the circuit using their pcb for $9 just haven't had time to tear back into the Crate.
Check out that link I posted. The guy put a 9v tap inside his V5.

[cebreez]

Thanks commodore... checking it out now.

[Ch0jin]

Not meaning to get off topic.. I'm also almost done with their double-flush tremolo pedal circuit. Have a new box coming in this week to put it in. Their boards are great and easy to build. Even their "advanced" and "genius" boards are simple for anybody with decent soldering iron skills. I do though suggest a small tip 40W iron and a good magnifying glass.

I've built a number of madbean projects and whilst they are nice boards, most of the ones I bought are NOT designed with any holes for mounting. This, to me, is not good enough.

It's ironic that you'll find so many "experts" rave on and on about how they hate anything PCB in an amplifier, but when it comes to PCB based pedals, people mount them using all of the worst possible ways. i.e. tape, glue, wrapped in foam, hanging off the pots or just flapping about. I'm sure the hard core "I have to make everything fit in the smallest box I can buy" crowd love it, but honestly, if your going to make a PCB for an Octavia that has a PCB mounted transformer, take a few minutes to add holes for mounting to the board! I hate that I had to velcro the PCB to the case! Take a page from Tonepad's book and please give me from one to four small holes in the PCB so I can screw the board to some standoff's inside the case. It's the classy way.

/end rant

But yeah, they are easy to make, I even made their FSH-1 fire up right away! (and that's a complex little sucker) Most recently built the loophole lo-fi looper and it rocks!

[cebreez]

Rant on friend! I agree. Had noticed the same thing. A lot of them do come with pcb mounted pots so that they are secured in that way. But I have already found one case where I would rather use solder lugs and arrange the pots differently on the pedal leaving the pcb without a mount. But you can still mount the board with the metal standoffs. Mount it so that the screws catch and clamp the edge of the board or like I do use your dremel tool or hacksaw to cut a slot in the standoff. Takes more standoffs but gives a very vintage look.

[Ch0jin]

I Like the slotted standoff idea! I use plastic ones epoxy glued to the box so that would work nicely. I totally know what you mean about control layout too. I usually find myself either changing the control layout, or wishing I could.

[jim p]

That pedal board op amp circuit will work fine with up to a 36 volt supply. You could run I off the same supplies in the V5 if you returned the -Vee pins to the -18 volt supply and replaced the virtual ground with ground. A higher supply voltage will give you more clean headroom.

I did a spice model of the mad beans active tone control pedal above and see if you want you can add a mid control pot. With the contour control being the bass, the process control the treble if you change R15 to a 10 k resistor and add a 50k pot in series to the inverting input of IC1B you have a mid control also. You can also change the cross over points of the tone control by changing the value of R11 for the high frequency and R14 for the low frequency a lower resistance value equals a higher frequency a lower value a lower frequency. The mid control will allow you to scoop or boost the mid frequencies.

[cebreez]

Thanks jimp! I like the sound of that!

[cebreez]

I looked at the circuit and thought not only of what you suggested but also of what I wanted out of the project as a whole. Bear with me while I roll off my thoughts. I'm not much of a "mid" tone person. On my peavey amp the "mid" stays just south of flat. What worries me about the amp as a whole is that without completely rebuilding the tube section the bass response is only going to be so good. Even with a better speaker the low wattage of the amp can only produce so much clean bass... right? Please correct me if I'm wrong. I assure you.. you know more about this than me. With just a speaker change the highs already sound pretty sweet without being shrill and harsh.
Now speaking logistically.... If you look at the faceplate I have 4 holes to work with. The contour and process (bass and treble) controls will occupy the 1/4" jack and volume locations and the jack will be remounted probably on the back, the gain and volume will occupy the tone and indicator lamp positions and the lamp will be moved right next to the power switch. This way everything stays evenly spaced and the switch stays on top.
Thats just to let you know where my head is at. And I have yet to test it after disconnecting the opamp circuit. Hopefully I can get to that later this weekend but I'm still waiting on some parts to come in. Namely a 68k resistor. May have to rob one from another circuit.

[jim p]

Just for what it is worth I think it would be better to build the active tone control as a pedal and go all tube on the Crate V5. If you got the V5 to have a tube amp I think you should go all tube because any op amp in the signal chain to me is going to add a bit of sterility to the tone. So if the active tone control was always going to be in the front of the signal chain anyway if you keep it separate you will have some flexibility. You could mount the tone control in the back of the cabinet and do a patch cord bit to use it or not use it. I don’t mean to be a purist about this but plugging straight into a tube is not the same as going through an op amp first. You have bandwidth limiting with the tube due to the miller capacitance. With an op amp after a couple of dozen transistors a jfet or two and a feedback loop you have an output signal. As far as bass response that is relative to a lot of factors. The primary inductance of the output transformer where in this case using a 16 ohm speaker with the stock output transformer would be best. The speaker used and the enclosure the speaker is mounted in. With bass being a low frequency signal having an open back cabinet can work against you due to the reflected sound wave from the back of the speaker. On the plus side at approx 100 Hz most speakers are at resonance making them very efficient in that limited frequency range. Another thing is if the amp is a current amplifier or a voltage amplifier. With a tube amp without feedback the amplifier is a current amplifier so at resonance and higher frequencies as the speaker impedance rises the power to the speaker will rise. With feedback or on a solid state amp where the amplifier is a voltage amplifier the power to the speaker will not rise at resonance or with the changing impedance of the speaker. Relative to the speaker load an its effect the first part of the article I posted here covers the impedance aspect http://www.wattkins.com/node/17999
Also this on the current amplifier versus voltage amplifier concept http://www.wattkins.com/node/16905

[cebreez]

Wow! You are the man jimp. The current amp versus voltage amp explains alot.


I don’t mean to be a purist about this but plugging straight into a tube is not the same as going through an op amp first.

I totally understand though that is not what I am attempting. I currently use the BBE Sonic Stomp on my pedal board and it stays on all the time. This is the very same circuit I am using in the Crate. It is not simply an active tone circuit but is meant to filter out unwanted harmonics and phase cancellations that would tend to make the sound muddy and muted. I have played through a fair share of small tube amps and this is very often the case.

That being said, the purpose of this amp is to be a practice amp. I need it portable and quick to set up without a lot of outboard gear to worry about. Since the bloviator (Sonic Stomp) makes such a vast improvement on the input signal and I foresee using it constantly it made sense to actually install it in the circuit permanently. I am doing away with the Crates opamp circuit and adding the 68K resistor at the preamp tubes input thus making this an all tube amp. The bloviator circuit is on its own board and wired through the input as if it were still a pedal plugged into the input jack. And just as easy to remove as it will be to install. Also gives me an entry point if I were to want to expand the circuit.

[jim p]

Just a thought on that active tone control circuit. You are changing the phase of the input signal by quite a bit. Any tone control circuit that is for the most part made up of resistors and capacitors will change the phase of the signal passing through it but within approx 90 degrees. With the active tone control shown the mid range frequencies at the output of IC2C will be 180 degrees out of phase from the treble from IC2B and the bass from IC2D. So quite a bit of phase change from the original signal. It could be interesting to invert the signal from IC2C with a unity gain inverting stage before connecting it to the summing junction of IC1B to see how that affects the tone.

[cebreez]

Ooooo.... Nice thought! I do believe that is the point of the original circuit. Any thoughts on how to put that into a switched application. Okay never mind.. I was over complicating the circuit. I could do that. I have thought about your ideas on this circuit... so I'm going to make sure this a plugin circuit and can be removed easily. I'm ordering another board and building a new circuit that I can spend some time modding. Thanks Jim!

[cebreez]

jim p, Just a thought..... It is because of the phase change of the mid range that it cannot overdrive the input of the tubes......Therefore will adding the unity gain inverter put the midrange back closer in phase with the bass and treble thus increasing total output gain and overdriving the input tube? Turning it basically into an overdrive circuit. Please say yes.... or is it not that simple?

[jim p]

The mid frequencies being out of phase from the high and low frequencies would have no real effect on your ability to overdrive the input tube stage of the amp, you need more gain and headroom for that. If you want to use the PCB for overdrive also the best thing to do would be to mod it to run off the +/- approx 16 volt supplies in the V5 for the stock op amp circuit or a 32 volt supply. Then you could take a gain of up to approx 10 at the summing amp IC1B without any op amp stage clipping. To me it looks like IC2A is not really necessary to the operation of the PCB you could just connect from IC1A to R7 and free up IC2A to use as a unity gain inverter for the mid frequencies or use it for a variable gain stage of 1-5. Also if you mod the board for plus and minus supplies then IC3 could be used for an inverting stage.

[cebreez]

I had already talked to the author of the circuit about running it off the Crates 12.9 supply and all of the caps I've been using are rated at 25V. The TL072 are rated at a supply voltage of plus or minus 18V so running them off of the 16.5V supply shouldn't be any problem. The mods to the board are getting beyond my level but I'm studying the circuit and the specs and am slowly getting back up to par. May at this time just think about putting in a boost stage... Got to get off the paper and into the circuit. I'm no good at computer simulations... I have to be hands on. But man you have got my creative juices flowing.... There is an easter egg in the bloviator circuit I am missing... Just something I remember from a circuit I worked on years ago. Gonna dig out some of the old books and see if I can find it.

[Glen]

I preformed the bypassing the op mod from jim p just would like to let you know that thanks to your mind and my hands I have a wonderful little amp. I upgraded the speaker with an Electro- Harmonix put there brand of tubes in I don't know if it was needed but i drilled a couple of holes in the back to help cool the insides. It was a pretty easy mod and I had no trouble doing it. I play a lot of jazz and blues so I like clean sounding amps. I own 3 amps and made my own abc block so I can turn them all on if I wish my Vox AC30 T/B was my main amp then my Hughes @ Kettner switch blade was next then the V5. I now use the V5 almost all of the time it just sounds incredible and the response from picking dynamics makes it a joy to play and it now has the power to run with the other two. The best part is if I want to play out anywhere I don't have to lug around a heavy amp just grab the V5 and my Zoom G2 and out I go. I might even try the reverb tank in the future, thanks for your time and hello to the Fretnet gang

Glen

[bcdon]

Welcome to The Fret, Glen! Introduce yourself over at the players section so everyone else can say a nice hello. Again, welcome aboard.