Crate V5 mods... anyone?

[jim p]

Re: Just hiss from amp

A quick check would be to jumper pin 1 of the op amp to R14 either side will work but the C24 side of R14 will give you gain (can also jumper pin 1 of op amp to pin 6 as a test). If the connection from pin 1 of the op amp that is common to both C24 and C26 is still open you will have no signal to the rest of the amp. From looking at the picture of the board in post #168 the traces connected to C24 are all on the top side of the board. Also whatever op amp you use it should be a FET input op amp for high input impedance.
Also check pin 4 of op amp for -15 volts and pin 8 for +15 volts.

 

[timmer114]

thanks

Thanks Jim, I'll take a look at it tonight and try the jumpers. You have been a wealth of V5 info, and I really appreciate the help =)

 

[timmer114]

sound again

I managed to jumper off the existing traces to the cap in C24. I have sound now, but it's very distorted and loud. The volume control is very sensitive, and it sound as if there's a boss DS-1 cranked in front of the amp now. Hrmmm i'll keep at it, thinking the op amp is the culprit here though.

 

[jim p]

A better reverb recovery amplifier

I have been bothered by the fact one of the last mods I do to an amp is to add reverb and when I do I get the 60 Hz noise back that I have been beating down. So looking into where this is coming from figure it is pickup on the reverb tank output. One of the bad things is that the output signal from the tank should connected to the recovery amplifier with a twisted pair inside of a shielded cable with the shield only tied to the recovery amplifier side. But even then the output of the reverb tank is a 1mV to 5mV signal at maximum and relatively high impedance. In all the tank installations I have isolated the input leaving the ground of the reverb tank through the reverb output shield. So a quick fix for that is to isolate the output RCA connector and run a ground wire to the chassis of the reverb tank. You still have a high impedance output from the tank so I thought of the FET buffer I have made for the guitar pickups but do to the reverb output coil floating you can even do better then that.

The buffer for the reverb tank produces a differential signal with a possible gain of up to 20 depending on the JFET used for the buffer. What this requires is to install three resistors and one to two capacitors in the reverb tank or right at the RCA jack. The remaining components are part of the recovery amplifier circuit. The circuit I built used a 2N6550 in the reverb tank but they are sold by only a few distributors and darn expensive. What you want is a JFET with low noise and high transconductance which is equal to low source impedance for the 2N6550 this is 25 to 40 mmho for 40 to 25 ohms source impedance. Instead of the 2N6550 in order of best to OK is 2SK170, BF862, BF861B and J309 the two BF fets only come in SOT23 package. What is unique about the circuit due to the fact you float the coil across the source to gate connection of the JFET you can get gain at both the source and drain side of the JFET. About the parts at the reverb tank the capacitor across the reverb output coil will cause frequency peaking so if you like twangy 2nF will do that I have no capacitor across the coil I did try from 100pF to 3nf something you can play with. R13 is to reduce the gain variation from JFET to JFET for maximum gain you can make it zero ohms. R1 is to set the current at between 1mA to 2mA if the current is high increase this if low lower it. R4 the 100k resistor could be increased to possibly increase the bandwidth of the reverb output or lowered to load down the tank for a darker sound say 50k to 25k ohms. So the source side of the JFET is connected to the outer connector of the RCA jack this is the low impedance side of the JFET while the drain is connected to the center conductor.

The recovery amplifier is a differential amplifier the gain of 10 from the JFET would be doubled if this amplifier was just unity gain but the amp has a gain of 10 so total gain is 200. So the circuit to the JFET is completed by the parts at the recovery amplifier R3, R2 R12 and R11. C1 and C2 along with R9 and R10 provide a high pass filter to help keep the low frequencies out of the recovery signal. C6 across the input will limit the high frequency input to prevent hearing your local AM radio station (because some of the JFETs are RF FETs). The first op amp U1 is to provide equal gain and high input impedance for the negative input to U2. The op amp can be an NE5532 dual op amp it has good low noise numbers and will work well for this application.

To sum it up I have a little hum but the power supplies in the Peavey Windsor I added this too are not great on the low ripple side I should add regulators.

Remember if you have both the input and output of the reverb tank isolate you will need to connect a ground wire to the reverb chassis. Also if you have a painted tank like a Ruby need to break the paint where the four springs that suspend the reverb assembly are attached to complete the grounding.

I want to correct one thing above the Jfet buffer is acting as a current source at both the source and drain so the impedance at the source and drain is the same 1 k ohms in the circuit as shown.

 

[timmer114]

I can't fix the thing, not sure what went wrong, but I went from having great headroom, to horrid gain at any volume position. Would burning up the op amp cause this? Something tripped the fuses in the amp, I replaced the fuses, and it powers on, but the sound is just beyond horrid with any tubes I use. It's pure distortion now. I can't seem to find which component failed that would cause me to lose all of my clean headroom. It's gotta be a cap after that op amp, maybe C25-or 26 or 21? I was able to jumper C24 to deal with the pulled up trace in that socket, but it doesn't matter at this point, it's all distortion.

Would a damaged op amp chip make the amp behave this way? I know I bumped an op amp leg with the soldering iron, but would that moment of heat burn up the op amp?

My gut tells me, that one of the components that shape the sound fried. The volume works, but the amp behaves like it's cranked wide open at the lowest volume, and only goes higher from there to a point of just chaos hehe.

Thanks for any tips, but I might need to try and locate a new circuit board. Loud doesn't have any in stock anymore =(

Hate to buy an amp just for the board, but I think I might end up having to do that.

 

[jim p]

Things to look for around the Op Amp

You could consider just getting rid of the op amp look at post #160 and #168. An op amp can take quite a bit of heat so I doubt you hurt it that way. If you have not replaced the op amp that would be a start. Without a scope and signal generator there are only a few things you can check. You should check the DC levels of the output pins of the op amp at pin 1 and pin 7 they should be close to zero volts. Also check the voltages at pin 8 and pin 4 pin 8 should be approx 15 volts and pin 4 should be approx -15 volts. If you get bad voltages at pin 4 or 8 check to see if R19 or R20 have not been damaged or changed value due to high current when shorted. Also check the voltages at R19 and R20.

 

[SciHi]

... but I went from having great headroom, to horrid gain at any volume position.

So does the volume pot actually work? Crate pots have a high failure rate, my master volume on my v18 broke near the ground, so there was no signal sent to ground, just a variable resistor in line, it was loud, ugly, and noisy. Use your vom to test make sure the pot has continuity to ground and is working correctly.

 

[timmer114]

Hi,

The voume pot does work, it's just the signal that comes out the amp sounds cranked and loud at the lowest volume. As I turn it up, it gets louder and louder to a point where the amp just then buzzes oddly.

Thinking back, I blew 2 fuses on the board. What caused this, I am not sure. But since then, it sounds horrid after replacing the fuses. I am guessing some component failed, I just don't know which component failed.

Symptoms :
Went from pure lovely clean headroom all the way nearly to full on distortion at lowest volume that only get's louder as I increase the volume. Even at lowest volume, it sounds nearly cranked sound wise.

Lots of crackling going on when I touch the volume pot. Hmm. Perhaps that is the issue now that I think of it. Okay that makes sense to me, volume sounds cranked because well.. it is! but then would the volume pot still turn the amp up even more?

What pot would I need to replace it if I can't locate one from Crate. Let's say I had to buy one from Radio Shack, what am I lookin for, just a 250k linear pot?

Thanks,

 

[jim p]

op amp voltages?

Just to ask did you check the voltages on the op amp pins as I posted before the negative supply is on pin 4 and should be approx -15 volts. Then there is the positive supply on pin 8 which should be approx +15 volts. With no signal in to the amp the output pins of the op amp should be approx zero volts so pin 1 and 7 should be very close to zero volts. You should be able to check the pot with an ohmmeter to see if it is OK. It is an audio taper pot. There is an advantage to having a capacitor between the two stages of the op amp if there is some DC offset into the amplifier so when I posted to jumper pin 1 to R14 this was meant more as a test and not necessarily a final configuration.

 

[timmer114]

The Op amp seems to be fine, I replaced it even and same thing, mega distortion and a really sensitive flaky volume pot.

Starting to wonder if it's the volume pot...if I tap the volume pot lightly, the sound cuts in and out, it always stays massively distorted, but the sound cuts in and out just by touching either the volume or tone pots lightly.. hrmm.

 

[jim p]

take a close look at the pots and PCB

Maybe the pot is bad or there is a bad solder joint going to one of the leads on the pot. I would look at the connections to the PC board and maybe just reflow them with a soldering iron and a little solder to make sure the joints are good. Also if you flexed the leads to much taking the board in and out one of the leads could have broken off from the pot. You could clean the pot it should not need it be being nearly new I use a little spritz of WD40 inside of the pot for that. Some people think WD40 is not a good thing to use so you can decide that for yourself. Also look to see if something near the pots might be shorting to the chassis.

 

[jfelser]

Excellent Small Amp with Modification

When I originally received the amp from AMS, I was thinking of sending it right back. But I bought it quite cheaply, so I figured at worse, I just got myself a reasonably priced 10" extension speaker cabinet. After googling mods for this amp, I stumbled onto this site. I immediately found a wealth of info provided within all the posts for the Crate V5. It helped me to make the decision of what direction to go. Thank you all!

Well, I just received back the PCB from my Crate V5 amp that I had Mark (deafelectromark) modify and I'm very impressed with his changes. These mods make this a very good small tube amp, with an excellent clean tone. I installed a Jensen P10Q speaker I bought cheaply on eBay a while back. Before reinstalling the head back into the cabinet, I tried several brands of EL84s and 12AX7s, a 5751 Sovtek and a couple of 12AU7s. I settled on a JJ EL84 and a Groove Tubes 12AU7, to keep the gain structure usable with my pedals. My Teles and Strats sound incredible, almost as good as through my Dr Z Maz 38 Sr, but at a fraction of the cost.

Now if I can only add some reverb . . . We'll be talking Jim

 

[schenkadere]

I'd like to get mine modded. I was in contact with someone here, but soon after lost the email and I can't recall his username. He had a mod for about 40 bucks...send him the head and shipping. Can't believe I lost that!!! This post just reminded me.

 

[larryx]

deaflectomarc v5 mods

Hello fellow fretters, well I wanted to thank one of our members named deaflectomarc. I just sold my v5 that was modded by him last winter. I got $350 for it! So thanks for not only making me money ,but taking a bad soundidng amp and making it really rock. All I had to do was throw a JJEL84 and a JJ12AX7 in it along with a speaker that I pulled out of my Marshall AVT20 and it sounds like a British Beast. Was the easiest sale I've ever made.


Thanks Mark!:applause

 

[schenkadere]

Hello fellow fretters, well I wanted to thank one of our members named deaflectomarc. I just sold my v5 that was modded by him last winter. I got $350 for it! So thanks for not only making me money ,but taking a bad soundidng amp and making it really rock. All I had to do was throw a JJEL84 and a JJ12AX7 in it along with a speaker that I pulled out of my Marshall AVT20 and it sounds like a British Beast. Was the easiest sale I've ever made.


Thanks Mark!:applause

Wow! I just put mine up on ebay...I won't get anything near that! :thwap

I did a quick demo that will either help or hinder the sale.

http://www.youtube.com/watch?v=8JQCkiDjRvw

 

[deafelectromark]

Stock vs modded Crate V5

Wow! I just put mine up on ebay...I won't get anything near that! :thwap

If you had sent it to me like you said that you were going to do, :crazyguy you wouldn't want to sell it, and when you were ready, you would get the extra money out of it. Loud industries took a good little platform and had 'too many cooks' work on it. Too bad they can't hear what they are doing- and I am the DEAF one!
I am still doing mods for $45.00 including return shipping for just the circuit board. If you want to send the whole chassis, it will cost you more in shipping both ways, but is less technical and more of a 'turn-key' operation. I add $5.00 to disassemble and reassemble the chassis from the circuit board and of course your shipping will be calculated to your home and shipping method. If you send me the weight of the chassis and zip code, I can get you a ballpark figure to help you decide if that is the best way for you to go.
Contact me via [email protected]
Mark

 

[SEDUK]

Kudos for the Deafelectromark Mod

This is my first post to the forum, but I really want to recommend Deafelectormark and his mod. I had been playing my V5 through an old combo amp I have with an original Celestion G12-80 in it and it sounded barely tolerable with none of the feel of a real tube amp. After following this string for awhile, I decided I did not want to deal with doing a mod myself, but I really wanted to make the amp useful. So I contacted Deafelectromark and he walked me through the removal of the PCB (no desoldering needed on mine), which I sent out for mod. Meanwhile, I ordered and installed an Eminence Legend 1058 (highly recommended in The Tonequest Report and only $49.95 with shipping included). Mark turned it around within a week or so and I installed it with new JJ tubes ($12 apiece).

What a difference! It is not even the same amp. The bass is incredible, it is very touch sensitive and seems to sing with harmonic complexity. My Highway One Tele with a Glendale "twang" set of brass and aluminum compensated bridges sounds fantastic and depending on the volume, can do clean country all the way up to early Led Zeppelin. Surprisingly, I am not even missing reverb, as the complexity of the tone fills out the sound.

My reissue 1959 Les Paul Standard (Epiphone version, which is a very nice guitar for few $s; I compared it with many Gibson Les Pauls and it holds up well) with Burstbucker 2 in the neck and Burstbucker 3 in the bridge just screams. I can get a great Cream "woman tone" by cranking the volume on the V5 with the tone control at 5 (max treble) and the guitar tones rolled off, middle position with neck on 10 and bridge on 6. Fabulous overtones!

Last, but not least, my Jimmie Vaughan Strat loves this amp. If you set volume at 7, use the bridge or middle pickup and guitar volume between 5 and 7, it has a fantastic Texas blues sound. I can play it all night and never get tired of the interplay between the amp and guitar. Oh---and I can do this in the basement without complaint from the family, as the amp volume is reasonable. Having a total of $175 in the amp, it is a steal; and I didn't even have to heat a soldering iron. This a great way to go for someone who doesn't have time or inclination to get into the mods themselves. Thanks, Deafelectromark!:AOK

Update August 23, 2010: I now use a ElectorHarmonix Holy Grail reverb with the modified Crate and it is great!

 

[raja7052]

nother kudos to deafelectormark

I sent my pcb board to mark to get the mod done, he turned it around in a week. what a difference, love the sound of it now. I highly recommend the mod to everyone and Mark is a real professional.

 

[Tarin]

Wow! i started this thread... my V5 is long gone and this thread's still busy.
Guess i'll have to start one on the Vox Tonelab ST pedal... one fine piece of equipment.

 

[deafelectromark]

Shure you started the thread, but it ain't dead yet

Wow! i started this thread... my V5 is long gone and this thread's still busy.
Guess i'll have to start one on the Vox Tonelab ST pedal... one fine piece of equipment.

Tarin,
P.s Why didn't you let me have a go at yours when you still had it?? Good iron, good chassis, good cabinet, just needs a better speaker and some sand kicked out of it. There are thousands out there- anyone want to sell me theirs?? I will fix em up. :dude
Mark

 

[Tarin]

Deafelectro...
Know what, yesterday as i finished posting on this thread, i kinda wanted to get back at modding one of this since i never got the chance (sold mine at the first offer).
You're right, it does have a well built cab... saw one on the local CL for 80 bucks, mmmmmm what to do.

 

[jim p]

Digi-Reverb

I posted this over at SEwatt and though I would post it here also for anyone thinking about adding reverb.

Well I am up to the point of ordering some boards made, just waiting on getting the Digital Sound Effector module form Belton somewhat. I have added enough holes to attach either the Sound Effector or the Digi reverb to the PCB. So figure I would go through a circuit description. The signal input to the board goes to W8 this connects to C5 in series with R4, R5 and R6 and the gate of Q1 a J211. The value of C5 a 1 nF and a total resistance of 1 Meg ohm will create a high pass filter to keep the bass out of the reverb (-3db approx 200 Hz). The connections W9, W10 and W11 are to replace R5 and R6 if a dwell (reverb input level) pot is desired. R4 can be used to set a limit on the maximum signal into the gate of Q1. Q1 the J211 jfet is used to make the signal input to the board a high impedance due to the fact the reverb module is a 10 k ohm input impedance device. W8 also connects to R3 that is connected to W6 and R2. W6 will be the connection to the control grid of the triode that was connected to the volume pot wiper. Moving back to Q1 (J211) its source is connected to R7 and C6 with C6 connected to R19 and C7. R19 and C7 is a low pass filter to limit the high frequency (approx -3db at 6.5 kHz) into the reverb module to prevent feedback the value of C7 can be increased if feedback occurs. The connection from R19 and C7 can be the input to the reverb module with R15 installed or the input to a common emitter amplifier with R10 installed. In the case of a VJ, Fender Champ, Crate V5 or any of the SE amps having the volume control followed by a triode connected to the output tube gain will be required before the input to the reverb module so R10 would be installed and R15 omitted.
The reason for adding gain to increase the signal into the reverb module is two fold, one the greater the input signal the better the signal to noise ratio this is the same for a digital reverb or a spring reverb. Second being a digital device if the signal is low less of the dynamic range of the system will be used and with low levels digital distortion may become noticeable. The gain required for a stock VJ is this, an EL84 will have an input voltage of approx 5 volts RMS at full power this is from the triode connected to its control grid with an approx gain of 50 so the signal at the control grid of the triode is 5 divided by 50 for 100millivolts RMS. Now with this board installed the signal to the control grid will be attached to a resistor divider R3 and R2 so twice the signal will be present at the volume pot wiper for 200 millivolts into the reverb module. The spec on the reverb module is 1.5 volts peak which is approx 1 volt RMS so 1 divided by 0.2 (200 millivolts) is 5 so a gain of 5 is required. Which leads to the common emitter transistor amplifier Q2 R8 and R12 are a voltage divider to bias the base approx 50 volts with a plate supply of 250 volts at W12 the input impedance to the base of the transistor is R8 in parallel with R12 in parallel with R13 times the transistor beta of approx 80 for approx 30k ohms. With R18 installed so the output of Q2 is connected to the input of the reverb module the AC impedance at the collector of Q2 is R9 50k in parallel with 10k for 8.3k ohms. The AC gain is 8.3k ohms divided by R13 so with 1.5k ohms for R13 it is 5.5. There is some signal loss at Q1 due to its source impedance of approx 160 ohms and R19 in series with the input impedance of 30k so overall the gain should be approx 5 from W8 to M4 (reverb module input). The output of the reverb module M2 through R16 is connected to W3 this point is to be connected to the reverb level pot. With the circuit as described the output of the reverb will be 5 times greater then the dry signal so you may want to half the input at Q1 by making R6 a 470k R5 a 470k and R4 1 ohms so it will just be 2.5 times greater. The reverb level pot connections are as above the top of the pot connected to W3 the wiper connected to W4 and the bottom connected to W5 (ground). To allow the use of a footswitch Q3 and R11 are on the board so when W13 is pulled to ground the mosfet is off and the wiper of the level pot is not shorted to ground with the switch open Q3 is turned on and the wiper is shorted to ground. When the reverb level is all the way up the mosfet will short the output of the reverb module to ground therefore you may want to use a 10k resistor for the value of R16.

If you were to add this module to an amplifier with master volume or a push pull amplifier where the signal level at the volume control is greater then 1 volt RMS R4, R5 and R6 would be used as a divider to limit the signal to 1 volt RMS. Then R15 would be installed so the signal directly from Q1 would be applied to the reverb module input. Then C11 a 100nf 100 volt cap would be installed and I would use a 20 to 25k ohm pot for the reverb level that will be connected to R17 with R18 omitted as well as R16 omitted. You will need to calculate the gain required for signal matching with 250 to 300 volts at W12 a gain of approx 22 is possible with an output of up to 180 volts peak to peak.
So unlike standard reverb tank connections with tube or solid state recovery circuits this circuit allows you to locate the reverb at a location in the amplifier with high peak to peak signal levels.

The power supply connections to the PCB are W1 and W2 with a 6.3 volt AC heater supply the two secondary connections go to W1 and W2. On an amplifier with AC heater supply D1-D4 are installed if a center tap is connected to ground it will need to be removed also if there are pseudo center tap connections through resistors in the amplifier they will need to be removed. W14 the AC ground should be connected where the center tap used to be connected. On an amplifier with DC heater supply D2 and D3 should be omitted to prevent ground loops due to diodes in parallel and W14 connected to the ground of the filter capacitor for the DC heater supply. If the amplifier has +15 volts you can connect the positive to W1 and ground to W2 then omit D2 and D4 replace D3 with a short and D1 with a 50 ohm 1 watt resistor.
With an AC supply D5, C3, D6, C4 create a positive voltage doubler. This is followed by R1 a series dropping resistor and D7 a 12 volt zener diode with filter cap C10. This provides Q1 the J211 with a drain supply of 12 volts because 5 volts would be insufficient to insure linear operation with device to device variation of jfets.

Regarding cost the parts are approx 8 bucks without pots the PCB 20 bucks each in quantity of three and the best price for the module is 15 bucks.

The schematic is here http://i1020.photobucket.com/albums/af330/vactube/Digireverbschematic31210.jpg

The layout is here
http://i1020.photobucket.com/albums/af330/vactube/Digireverbpcb31210.jpg

Let me know if you find any errors, thanks.

 

[jim p]

I have three blank PC boards on order by what things are costing out to be if I had 10 or more people who wanted these the cost would be around 40 to 50 bucks. That would be all the parts on the PCB required and the reverb module you would need to do the assembly. It might be possible to include the level pot at this price also. (the knob?)

 

[deafelectromark]

Or just send it to me- between jobs need $$

I have three blank PC boards on order by what things are costing out to be if I had 10 or more people who wanted these the cost would be around 40 to 50 bucks. That would be all the parts on the PCB required and the reverb module you would need to do the assembly. It might be possible to include the level pot at this price also. (the knob?)

Reverb is better outboard as well as the effects. Amps are what they should be be. Amps- and nothing more- nothing less. KISS
M:dude

 

[jim p]

Almost complete

Well I thought I would post what I have for right now. I have the PCB and have installed most of the parts for operation. I tested the FET buffer stage and common emitter stage using two 9 volt batteries for a power supply. The FET is OK with an input signal up to 1.5 volts RMS so no problem being the largest signal in should be limited to 1 volt RMS. Also with the VJ it will only be 200 millivolts at full volume out. Loading the common emitter stage with a 10k resistor I got a gain of 4.8 so that is OK also. The one down side of the cheapest PCB from ExpressPCB is all the unmasked copper makes it easy to have a solder bridge on the board (I had two from assembly). If I do the boards in a quantity I will see about solder mask and silkscreen to make life easier. I don’t yet have the Digi-reverb module but I do have the Sound-effector which is the same size so I used that to check dimensions and to take pictures for now. With the module mounted on the back using nuts for a gap the PCB and module are 1.5 inches high by 3.8 inches by 2.5 inches. If you mount the module off the edge of the PCB on the top the height is 1 inch with a width of 3.8 inches by 3.8 inches.

http://i1020.photobucket.com/albums/af330/vactube/frontmountedmodulepic.jpg

http://i1020.photobucket.com/albums/af330/vactube/sideviewbackmountedmodulepic.jpg

http://i1020.photobucket.com/albums/af330/vactube/topviewreverbPCBpic.jpg

 

[jim p]

it works great

Well I built up a board and first installed it in a Ver 1 VJ combo amp with AC filaments. Couple of problems with that being the first stage triode plate trace runs parallel with the control grid for the second stage so with 330k in series to the grid and 330k to ground you have signal with the volume pot turned all the way down due to coupling. The second problem was AC pickup that did not exist with the stock setup so instead of adding a DC heater supply and cutting up the pcb I put it back together to try a different amp.
Next I put it in a Crate V5 that has been modified by removing the op amp that was on the input and has the volume control between the triode stages. The AC heater supply for the power tube is tied to ground on one side in the amp so on the reverb board only one diode D4 is installed and a short is installed at D2. Then W1 is wired to ground and W2 is the AC input to the supply. I used coaxial cable to connect to the wiper of the volume pot to the input to the reverb board with the coaxial cable grounded only on the volume pot side also used coaxial cable on the output of the reverb board with the ground near the control grid. This uses the voltage divider of R2 and R3 on the reverb pcb to mix the signals. With this I was getting some AC pickup (ground loop or pickup of AC to DC supply on pcb) so I put the resistors for the signal mix down on the amplifier pcb with 330k from the volume pot wiper to the control grid and 330k from the control grid to the wiper of the reverb level pot. With this I get just a little pickup when the reverb level is at maximum which is surf guitar level. Adding a ground from the signal side of the reverb board to a ground near the triode control grid took a little more of the noise out.

I need to see what the signal levels are like on the pcb I split the input to the board with two 470k resistors for half the signal into the board. But found I lost a lot of gain at the common cathode amplifier output so the module input is less then 10k as the data sheet states.
I will have to look into getting some sound clips posted.

The reverb sounds fine at least equal to the digital reverb in the Bugera V5 I have. On the Bugera I did change the stock input to the reverb to a connection at the volume pot. I also changed values in the common cathode amplifier on its output due to clipping on the stock circuit.

I plan on adding this reverb to a 6AQ5 push pull amplifier that I just got a Hammond chassis for.

 

[jim p]

Looking at the signals

Looking at the input and output of the Digi-reverb I am getting numbers that are different then the data sheet. Part of the problem could be the approx 30 years old Phillips scope I am using, but instead of 1.5 volts peak it looks like the most you want at the input is 1.5 volts peak to peak. One thing I am sure of is the input impedance is closer to 4k then 10k ohms as the data sheet states. The reverb looks to peak with more gain at approx 2 kHz then level off. There is also some nasty looking high frequency odd harmonics in its output if you do overdrive it. So it looks like I may have just needed a jfet buffer on the input due to the low input impedance and you don’t need the common emitter gain stage so much. I might increase the frequency roll off into the reverb module by increasing the capacitance in the low pass filter I have after the jfet buffer. Wishing I had a digital scope to freeze the signal coming out of the module to get a better idea of what is going on. Also be nice to have one that has been calibrated in the past decade.

 

[jim p]

Sound clips od Belton Digi-reverb in Crate V5

I have posted two sound clips of the Belton Digi-reverb mounted on the PCB I designed installed in a Crate V5 amplifier. It is my son playing with the amplifier connected to a cabinet with two Jensen Special Design 10 inch speakers. The reverb is set at the mid level in one clip and at maximum in the other.

 

[mars2010]

re: crate v5 with reverb

I have posted two sound clips of the Belton Digi-reverb mounted on the PCB I designed installed in a Crate V5 amplifier. It is my son playing with the amplifier connected to a cabinet with two Jensen Special Design 10 inch speakers. The reverb is set at the mid level in on clip and at maximum in the other.

after reading through all these pages of mods

these sound clips are great, very nice playing and tone...
:applause

it's incredible how much time and dedication jim p put into working on this amp
very interesting stuff...

 

[DeanEVO_Dude]

I just picked up my Crate V5 amp, changed the speaker (Eminence Patriot Ragin Cajun) and I kinda like the way it sounds... They should have added $50 to the price and equiped it with this speaker to begin with.

Anyway, my soldering iron will be aquainted with this amp either next weekend or the one after. The first thing that will change is the gain on the op amp, move it more 1.5:1 or so on the first stage and around 2:1 on second stage. Then to tackle the the tone control... But one mod at a time...