Sluckey Revibe - My version

[Bombacaototal]

I am taking a break from building Dumble amps for now.

I have the biggest admiration for Sluckey, an avid contributer at the forum and helped me tremendously with the tremonator circuit when I was chasing the Borderline trem circuit.

His enhancements on the revibe always caught my attention and I finally had a chance to build it.

https://sluckeyamps.com/revibe/revibe.htm

I wanted to challenge my self and fit everything inside a 2U/19"/20cm rack, and the attention to detail as far as placement of everything taking into account the 3D space was definitely daunting and fun simultaneously.

I designed the PCB board with guidance from my good friend Ryan, thetonegeek.

I decided to place the tubes at the back of the unit, like an amp, for easy access, better ventilation and space optimisation. The unit will gain a headshell which is deep enough to protect the tubes.

I finished the wiring and it's ready for fire up. I am just missing a lead from the RCA jacks to ground.

I am conscious of lead dress importance on the tremolo circuit and plan on checking that once it's all up and running

Below some pictures of the project

[dbharris]

Looks great! Would love to hear a clip.

-Dan

[bepone]

i see very thick traces...finally very nice

[Bombacaototal]

i see very thick traces...finally very nice

Good spot, I used 2 oz outter copper weight! Super nice

[Raoul Duke]

Looks very tidy and well designed!

I’m right there with you about being a fan of Mr Sluckey also. Got my eye on a design of his that is AC15 on one channel and JTM (I think?) on the other. That really interests me.

Yours looks really nice. Bet it sounds killer

[Bombacaototal]

Fired it up, no smoke, all voltages in check. Signal test was fine as well.

But I have some issues. First is a ground loop.

I was reading this post which has a comment from Jeff Gehring, the original designer of the revibe
https://www.thegearpage.net/board/index ... s.2476405/

Here's the deal: IF you ground the chassis with the AC cord safety ground wire, and you have ANY of the revibe circuit ground points tied to the chassis, you will get a ground loop.

To avoid this you can do one of the three following solutions. I'm going to try to keep this as simple as possible and as high level as possible:

(1) Build the unit grounded like an original reverb unit, but do not connect the AC safety ground to the chassis at all. This is a BAD choice.

(2)Build the unit with ALL the circuit grounds confined to an isolated buss which is NOT connected to the chassis directly. (This includes ALL jack sleeves, RCA and 1/4", as well as all other circuit ground points) The isolated ground buss must connect to the chassis steel ONLY via a 16 ohm resistor and three other components connected in parallel with the resistor: a 47nF or so cap, a rectifier diode connected with its cathode to the chassis, and a rectifier diode connected with its anode connected to the chassis. When your build is ALL COMPLETE, you should be able to take a meter and measure 16 ohms between the chassis steel and all the component/jack lugs connected to the isolated ground buss. If you measure zero ohms, you have messed up and somewhere connected a circuit ground to the chassis steel. This is the method Fender used in their reissue reverb units to eliminate the ground loop yet permit a grounded chassis.

(3)Build the unit, grounding the circuit to the chassis steel, AND connecting the AC cord ground to the chassis steel too. BUT you must use an audio isolation transformer between the output of the revibe and the input of the amp. The audio isolation transformer can either be built into the revibe, or it can be a stand alone product. Whatever is used, the transformer must provide galvanic isolation between the revibe's output and the amp's input.

NOTE: Some people will say just use a cord with the shield lifted at one end. I have NOT found this to work at all in this case.

Sluckey had a different grounding which I followed. Basically one for the mains, one for the PT CT, one for the reverb circuit and one for the power supply and trem circuit. Input, output and RCA grounded at the chassis.

I have mine identical, except I had my RCA's isolated and grounded to the reverb ground star. I have tried the RCA jacks to the chassis but the ground loop is worse.

I have tried to move the RCA grounds to different spots and also have moved the trem ground to different spots, no avail

My amp has the HumX circuit (courtesy of Ryan thetonegeek) on a switch, which besides the normal ground allows to isolate the mains via 2 diodes and a resistor, somewhat similar to Jeff point 2 suggestion but tackling the AC rather then the entire circuit ground. It makes no difference between the two options

Another thing is that the amp sounds super wet, if I have mix and dry level at 12 o'clock (attached). Even with the dry level maxed out it is still fairly drippy and wet. I also noticed a slight volume drop and the tone becomes much darker and muffed with the circuit Vs straight in the amp.

Last issue is interference being pick up by the LFO. I have removed V5 tube to tackle the other stuff first. I noticed lead dress is super sensitive and there was also this video from someone who built the revibe with similar issues for reference

https://youtu.be/M4e2K92HYKg?si=wUXebL8uTkbgoJmM

[sluckey]

First is a ground loop.

I simply disconnected the power cord green wire from the chassis to solve the ground loop issue. Guitar strings are still connected to earth ground at the main amp. I don't see this as a bad solution. If I were to build another revibe, I'd use the grounding scheme found in the reissue reverb unit. BTW, there are several successful revibe builds that used my layout.

Another thing is that the amp sounds super wet, if I have mix and dry level at 12 o'clock (attached).

Well, don't set the mix to 12 o'clock. The mix is simply a reverb level control (same as any volume pot). Reverb level can be adjusted from zero reverb to way too much reverb.

The dry level (I labeled it vibrato level on my front panel) simply controls the guitar signal level sent to the vibrato modulator. This pot was added to compensate for guitars with active or hot pickups that could overdrive the vibrato modulator and make an unpleasant sound. Just set it for a nice "dry" sound with the vibrato effect disabled. If you always use the same guitar you should not need to readjust. I had considered using a locking pot with a screwdriver slotted shaft on my revibe.

Last issue is interference being pick up by the LFO.... I noticed lead dress is super sensitive

I don't have this issue, and my lead dress is not sensitive.

The tone is affected due to the dry signal always going through the vib modulator. I figured this is just the way it is. I'm able to brighten the tone using the controls on my amp.

[Bombacaototal]

Many thanks for the kind response and all the additional insights and details Sluckey, I really appreciate it! Also thanks on the insight for the level control.

Attached is the ticking I get with the tremolo. I have replaced the led and checked the cathode (-, or flat side) is indeed to ground. The leads coming off the trem board are super sensitive and I can hear differences when I move them with the chopstick.

But, the main reason for me to build this unit was the reverb, and having the circuit going though the trem path, really dropped the tone (similar to getting my guitar tone pot half way) and also dropped level. I jumpered the exit of the dry path (attached pic), the other side of the level pot, straight to the output jack, and wow, that is definitely the kind of reverb I was hoping for, and bonus, no ground hum.

I think having both trem and reverb is a bit of a compromise situation, and given the reverb is what I want, I will just use the reverb circuit and remove everything else (as far as leads and knobs).

I might try the tremonator with that LFO tapped off the output jack

[Bombacaototal]

Added the tremonator mods using the stock lfo, tapped off the output, but changed intensity pot to 100kb as a variable resistor (per borderline iteration). Will need to fine tune the resistance for a good range, but benefit (instead of a normal pot) is that there is no signal bleed to ground.

Will be able to test tomorrow. If it works I am thinking of adding a relay to light up the led when trem is engaged, but I will have to see how to do it with the small space I have left

[Bombacaototal]

Sounds phenomenal! Both reverb and trem! Super happy with the unit now, just small things to look at now. The fast/slow doesn't seem to make a huge difference, and actually sounds like it's wired in reverse, switched between them towards the end of the recording.

Will need to reduce the intensity range to about half (50K ISH)

Also want to figure out the led relay!

[sluckey]

That does sound good! I'd really like to understand exactly what you have changed. Can you make red line changes on my original schematic to show us exactly what changes you have made? If so, I can use it to edit the original schematic to show your version for you and anyone else that may be interested.

[Bombacaototal]

That does sound good! I'd really like to understand exactly what you have changed. Can you make red line changes on my original schematic to show us exactly what changes you have made? If so, I can use it to edit the original schematic to show your version for you and anyone else that may be interested.

There you go! Really pleased with it. I ended up with the same 24K on top of the 100KB pot, as I like the effect more prominent
I just need to figure out the led now
I may try to make the slow setting on the toggle slower although not sure it is possible
Also not sure why the reverb footswitch not working, will need to investigate further

[sluckey]

I just need to figure out the led now

Experiment with this. May need to play with the 10K cathode resistor too. Of course, it may not work at all!

[Bombacaototal]

Led is sorted, sort of, I had on hand a 2V led, and when I measured the footswitch side of the vectrol I had about 1.5V when trem is not engaged and zero when it' is on, which is perfect for the spec. It blinks when the trem is off and it is off when the trem is on, a bit weird. It flashes to the speed pot tempo (I believe although it is subtle). It is different than your schematic, I'm basically running it sort of in parallel to the vtl led

[sluckey]

Put a red LED (not green) in series with the VTL5C1 LED. If it works the LED will flash when the tremolo is on.

Why red (or yellow) LED? Because a red or yellow LED has a lower voltage drop than the green LED. Putting the LED in series with the VTL will increase the bias voltage on the cathode of the oscillator tube. This is why I say it may not work. Worth the try though. Easy to do.