I've been reading up in the Hoffman ReVibe, which is a combination of the Fender tube reverb and harmonic tremolo. Well, I've got the SurfyBear spring-pan reverb PCB on the way and fortuitously our own Midwayfair has created a brilliant little harmonic tremolo. So they just have to be paired together. It's destiny.
There are just so many variables I'm not sure the best way to do it. Floor unit, like the VanAmps SoleMate? I have a hard time picturing how that's all going to fit together in a 10" X 6" X 2" Hammond box. What about an enclosure on my amp cab and under the head with remote footswitches?
Then there's the implementation. These thing really belong between the preamp and the power amp, but I'd rather not modify my amp since it's a 'booteek' and it's brilliant. What about series & parallel? The ReVibe runs he effects in parallel, so do I need to design a mixer to marry these beauties?
Love to hear what you guys think. Here's some pictures of what's out there:
(http://cl.ly/image/220I0i0j0N1G/ReviBeSchem.jpg)
(http://cl.ly/image/1K0f2O1P2p2n/SurfyBoard.jpg)
(http://cl.ly/image/1g3V3B0L0y2z/SoleMate.jpg)
I got my self etched SurfyBear reverb and I have been wondering what I was going to put it in. I even looked at the mini Accutronics tanks used by some of the synth rack units and doing a pedal. I am really interested in the direction you are going with this and can't wait to see what you come up.
If you want to run the Cardinal in parallel with something, you pretty much just have to add a non-inverting buffer after the volume pot. But there are probably better implementations if it's going in an amp ... PM me if you want more specific thoughts. Mostly it involves removing the "amp simulation" aspects of the Cardinal.
Quote from: selfdestroyer on January 08, 2014, 11:47:15 PM
I got my self etched SurfyBear reverb and I have been wondering what I was going to put it in. I even looked at the mini Accutronics tanks used by some of the synth rack units and doing a pedal. I am really interested in the direction you are going with this and can't wait to see what you come up.
I've had the 9", 3-spring Accutronics tank for a few years and haven't liked any of the circuits I tried with it - none sounded nearly as good as the SurfyBear demo. I went through a lot of schematics at SS guitar and tried some of the Orange and other Opamp reverb drivers/recovery circuits and they were just too weak.
Quote from: midwayfair on January 09, 2014, 12:20:36 AM
If you want to run the Cardinal in parallel with something, you pretty much just have to add a non-inverting buffer after the volume pot. But there are probably better implementations if it's going in an amp ... PM me if you want more specific thoughts. Mostly it involves removing the "amp simulation" aspects of the Cardinal.
I'm keeping the amp stock, for sure. Often tempted to monkey with it, but it's great just how it is.
I'm also definitely leaning toward the parallel option just to stay consistent with the original idea.
Guessing Input buffer to split signal (opamp a) -> Reverb -> Mixing opamp (opamp b)
-> Cardinal -> Mixing opamp (opamp b)
I haven't given any serious thought to the circuitry or switching yet. I keep thinking the first hurdle is to figure out the setup - floor or unit under amp head.
Now in my dreams ...
(Whiddley woo, Whiddley woo, Whiddley woo)
Now that we're in the fantasy world, the reverb and tremolo are integrated and built under a big, custom pedal board with programmable switching.
For inspiration. Almost convinced I need to pony up and build the tube version somehow someway.
Skip to about 2:40 for the really good stuff.
Sounds just excellent, even with just the Ins/outs tied together. There's waaaay more reverb in this than I'll ever use. I also think I should get bigger heat sinks - Mosfets get REALLY hot.
(http://cl.ly/image/3W1i3m192H1l/photo%201.JPG)
Also curious, would anyone be interested in a version that just uses a Belton brick?
:)
Do you have a way of recording a clip? Both these are on my to do list...sometime
Quote from: jubal81 on January 18, 2014, 07:49:30 PM
Also curious, would anyone be interested in a version that just uses a Belton brick?
Whatever you pull out, i'm in, this sounds like it's going to be the holy mother of lushness! 8)
Quote from: jtn191 on January 18, 2014, 10:30:51 PM
Do you have a way of recording a clip? Both these are on my to do list...sometime
I'll try to do something with my iPhone tomorrow. Once it's done I'll find someone with a mic setup.
Quote from: GrindCustoms on January 18, 2014, 11:25:02 PM
Whatever you pull out, i'm in, this sounds like it's going to be the holy mother of lushness! 8)
There's a good reason this combo is a classic. It's really something special. I had them in series for a while and it sounded great, but when I tied the leads together - wow. That's what made me think a good project needs to be made - and I'd like to have one that fits in a normal pedal enclosure.
(http://cl.ly/image/2f410F3I0F2t/Jackie.jpg)
Oh yeah, that's fixed now.
Got the splitter/mixer going today and tweaked a bit to get it working pretty well.
Issues:
+For the reverb, there is some distortion when the dwell is pushed. Think I might try a smaller coupling cap than the 100uF.
+The recovery stage could use some more gain because as the mixer goes up, the overall volume goes down.
+ Going to switch out the Dwell & Mix pots with audio taper - needs more play in the low range.
Still can't decide on the switching. I can't see ever using the tremolo without the verb, but definitely the other way around. Did an A/B with series/parallel and haven't decided if series operation is worth a switch.
And I came up with an insanely complicated, but very cool, idea for the construction involving tinted lexan and el panels. :o Shielding may be an issue ...
(http://cl.ly/image/3M1O1G0b1b2Q/Mixa.jpg)
(http://cl.ly/image/2F3K2c0E001f/Screen%20Shot%202014-01-21%20at%202.38.06%20PM.png)
Soliciting suggestions for getting more gain from this stage:
(http://cl.ly/image/231l1M0l0q0I/Screen%20Shot%202014-01-21%20at%203.22.28%20PM.png)
It's basically a Mu Amp -- Make it an SSRP instead. http://www.geofex.com/Article_Folders/modmuamp/modmuamp.htm
The SSRP is the version I used in the Clipper Ship. I think you know how much gain that had. ;) But among other things, the SSRP is also less noisy and has fewer loading issues (I stuck a tone control AND volume control on it and it still had over 20dB.
Or you can use this thing I've described here:
http://www.diystompboxes.com/smfforum/index.php?topic=105261.0
9V --_-------_
| |C (Q1)
R1--->]B
| |E >--C1
R2
|D (Q2)
in--> ]G
|S
R3>Ground
Q1: NPN BJT. Q2: N-channel FET
The gain on that stage is not quite as high as the SSRP, but it's a ton of DC gain, it's not overly distorted, and it has very low current draw.
EDIT: The omega can be adjusted to have clean output as well. http://www.runoffgroove.com/omega.html
ANOTHER EDIT: I realized, though, that you were hoping not to redesign. Sorry. There's not a whole lot you can do within the topology, assuming the FET's bias is settling properly.
Thanks for the input. I suppose I could do some desoldering and dead bug an extra resistor in there for the SRPP. What sticks out to me is that 100K drain resistor. I've never seen that there like that before.
It doesn't need very much more gain at all - just a smidge to get it to unity. Maybe I could attenuate the dry line a hair so they match and then do the boostification in the mixer ...
(http://i41.tinypic.com/2ut59j8.jpg)
Alright all fixed. The driver transistors needed some rebiasing. Changed R13 from 2.2K to 390R and R12 from 10K to 20K.
No hint of distortion on any dwell setting and unity volume. Just tons of warm, luscious reverb.
Mixing board laid out and ordered. It's going to be a long couple weeks.
(http://cl.ly/image/1J3k0T0x460O/Screen%20Shot%202014-01-22%20at%209.54.59%20PM.png)
I've decided I'm going to go with a floor unit - Solemate style. Hammond makes a 10"x6"x2" that I think I can make work - if I take the spring unit out of the housing and remount it in the hammond box. After doing some reading, the housing is meant to shield the springs from magnetic fields (transformers). No transformers in my build, so I don't see why it would be a problem.
I'm also abandoning the illuminated panel idea. I found out the El Panels I can afford:
1) aren't that bright
2) Dim significantly over time
3) only last about 100 hours
Now I'm thinking of using a clear acrylic panel with transparencies/paper underneath and I have plenty of Tweed on hand. Having trouble finding dial graphics I like. though.
Now that was seriously speedy - nine days from order to my door.
(http://cl.ly/image/383Q3n144034/photo.JPG)
Box and a few other parts finally got here - damn ye, snowstorm.
I'm leaning toward the white knobs.
(http://cl.ly/image/232C3s3b0m1v/whites.jpg)
(http://cl.ly/image/0S3W0G2I1J1E/blacks.jpg)
I vote for the white knobs too.
White! Very snazzy.
Officially getting very awkward to work with (up to 4 boards wired together, now). Trying to get creative with 1776 relay board - using a TLP222G opto FET to use the relay board to use the rate LED as on-off indicator.
Spent yesterday dialing in the Cardinal. Swapped in 2N5457s for Q1&2, biased (looking for max headroom) and wired up a rotary switch for the modes - the two standard and a 39n C6 for vibe mode. I already updated the graphic, just need to print out a new one.
(http://cl.ly/image/3r3c0I3U1I17/photo-2.JPG)
Good news: The switching works as intended - rate & indication with one LED.
Bad News: Back to the bias drawing board with the Cardinal - getting a bit of clipping again today. Ugh.
I've also decided that instead of grounding the input mixer to drop out the tremolo, I'm going to wire it to provide the bypass signal. The problem is that just cutting out the tremolo is like cranking up the dwell knob, but when I want to turn on and off the modulation, I just want the modulation on or off. Simple fix.
Hours later:
If the Cardinal didn't sound so amazing, Id've given up on it. Top prize for most difficult circuit I've ever tried to dial in and get working consistently.
Changing Q3 to 5457 did add more headroom, but now the effect is voiced very differently. Whew. A few more lifted pads and I'm going to have to order another and start from scratch. Just hope I don't futz anything up get those opto out.
Whew! just barely.
R9 pad lifted but I got in there and patched it up. The magic number for R9 with the 5457 was 1K. I brought the vibe cap back down to 33n.
I finally think I'm golden on this sucker - out of this world sound on all three settings and I can't get it to clip with single coils - hum buckers will still rattle it, though. I was hoping to have it boxed up by now, but I'm feeling great about how it's working and sounding - just wish I hadn't fallen victim to my own hubris and socketed the transistors and drain resistors.
Looking positive ...
(http://cl.ly/image/200M3P3n2Q0D/photo-4.JPG)
A couple hours yesterday and 10 hours today and I've got a preview. Still waiting for knobs. Everything worked right off the bat, which was a relief because I depleted what I thought was a hefty strategic wire reserve.
I used little velcro squares from Walmart to secure the boards and I really like it.
The 1776 relay boards work great and are very quiet.
Oh yeah, what you see in the corner is a Bloviator II. I put it on top with a DPDT to use as a switchable output buffer.
I need a better solution for the faceplate. What you see is just a printed presentation paper under a piece of lexan. I got it on and together, but it's just rickety. Maybe you guys can give me some ideas on how to get something pro on there.
I also have got to find a way to make a good demo. This sounds so great you just can't believe it. It's utterly sublime.
(http://cl.ly/image/0Z2r103z3b1q/photo%202-2.JPG)
(http://cl.ly/image/1V3e2i2M0o2X/photo-5.JPG)
So without any changes other than playing it every day, the Cardinal is back to being a hybrid tremolo/overdrive. It was clean - now it's gotten dirty on its own. Never seen that happen before.
Really as far as overdrives go, it sounds pretty good, but I need a clean tremolo. Really frustrating because I had it working well and now it's going to be holy hell to get back out of there.
EDIT: Got it to behave again after rebiasing Q1. Ended up with 8.76 on the Q1 drain using a 470R resistor. About 4 hours to swap a resistor. Ouch.