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  #1  
Old 11-19-2010, 07:57 PM
wabbitguy wabbitguy is offline
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Default iPatch - Guitar Pedal Switcher

As a musician and electronics buff it didn't take long before I envisioned building a stompbox pedal switcher that actually provides proper true bypass as opposed to the stompbox pedal norm of FET bypass (that robs tone from the signal path).

A true bypass stompbox removes both the input and output from the guitars signal path and usually the pedal will advertise "TRUE" bypass. This isn't completely true 100% of the time, but until you take the pedal apart to see how it's wired, you can only go by what's written on the packaging.

The common practice for an effects pedal (Line 6 or Boss for example) is to use FET circuitry that either routes the signal through to the "effect" or to the output. Unfortunately this form of bypass tends to diminish the tonal range because of the "bypass" circuitry.

Even pedals with a true bypass looking stomp switch can be misleading. For example, the switch will route the input signal to the output to bypass the effect, but will leave the pedals output stage connected to the output. Again, this will present a load to the signal and tone can and usually does suffer because of it.

The situation is compounded by the multi-pedal boards that guitarists use. Each pedal takes it's toll on the ultimate sound and there's no way to correct it after the fact.

I'd been using a VooDoo Labs Pedal Switcher for a few years and it's great for studio or live work. It's initially how I started testing pedals in their bypass state to see how badly they affected the tone. The results in some cases were quite astounding and I stopped buying pedals from some manufacturers because of my testing. However, the Pedal Switcher was limited to five pedals, had an odd ball MIDI sysex control setup that I didn't like.

I'd also checked out other switchers, like the RockTron PatchMate 8. Which is a good unit, but isn't all that programmer friendly. None the less it's still an excellent unit.

When John announced the new version of the MSA-R, that was all the push I needed to decide to build my own. My design criteria was:

1. Input normal or buffered (makes up for long input cable loss)
2. Complete remove input and output signals from path
3. MIDI controlled (and easy to program)
4. Firmware upgradable

I selected the MSA-R as the brain, mainly because if I scrapped the whole project the R unit can be used for many other things. However, the MSA-R relays are only single pole and I needed to remove both input and output signals. Hence I required a DPDT relay setup.

I designed a relay PCB board, some driver transistors and LED output indicators. And then I happened to be searching for relays on eBay and came across a pre-built board solution:

DPDT Relay Boards

I viewed these as a cost effective solution that saved me the time and cost of building my own. I had no idea of the quality of the relays, but as it turns out, they are quite serviceable. Of course they aren't the "gold plated" relays that some switchers use, but I ran some signal tests with my scope and they work good enough for my application.

I purchased four relay boards, unsoldered the LED's and replaced them with pin headers that I could clip to for the front panel LED's. I wanted the indicators on the front for relays for the audio, not the LED's from the MSA-R.

Next was the input buffer. I'd originally bread boarded the thing on a piece of cardboard since it's a very simple circuit. I was running off a battery but decided to run it off the 12VDC supply by wiring in 4 diodes in series to drop the voltage to 9.6. That worked perfectly, and audio scope tests showed no discernible audio noise. This really helps to make up a decent signal strength when you're using those 20-25 ft guitar cables so the pedals have signal to work with.

Again, I was going to build a proper PCB and then I found the exact one on General Guitar Gadgets:

Input Buffer

Granted a little pricey for an unpopulated PCB, but it saved me the time of having to build it so I could work on other things.

Last was the multitude of 1/4" input jacks. Rather than make a PCB and mount all the jacks, I chose the lug style to use and they also have switch capabilities (inserting a plug will interrupt the switch). While not Neutrik gold plated jacks, they work well and cost effective.

The toughest part to find was the 19" 1U rack unit that was only 6" deep. Plenty of 10's and 12's out there but 6" ones are tough to find. The one I used is made of 18 gauge steel, after drilling it, I seriously wish it had been made from aluminum...

I run the iPatch from a 12VDC regulated wall wart and here's what the completed project looks like:



And the rear:



I didn't label the SEND and RETURN, because I wired it the same as a normalled patch bay. Send is the upper jack, return is the lower jack.

I decided to go with blue LED's for the front panel so I had to change the relay board resistors to allow additional current, the blue LED's, while only a 25 degree viewing angle are so bright (1200mcd) they light up the studio or stage. Significantly..

I also used a super bright yellow LED for the "act" LED on the MSA-R. Since it didn't supply enough current, I used a PNP transistor to drive the "data" LED on the front panel.

Were I to add enhancements to this project, say for version 2, one area would be each channels input/output path.

At present, the signal flows from 1-8, if you turn on a channel that doesn't have a SEND jack in it, the signal still passes through (the switches on the jacks allow this). If you want to rearrange your pedals, you have to unplug and change their order in the chain. To make the unit more versatile, a separate input, send, return, output would be the ultimate. A setup like this would allow you to use effects in parallel and the sound from this style setup is far different than a standard series setup (you then blend the effects signal with the raw signal). Or if you use multiple amps. Nice signal splitter.

Also with this setup, changing the signal path is merely moving the Out's to In's order with short patch cables. You could even add a buffer to each channel to further enhance the signal although this might invoke the law of diminishing returns...

One other area I plan to address is the lack of a MIDI Thru jack. There's no room to put one on my chassis so I'm going to use the un-used pins of the OUT jack and built a custom MIDI cable for it. This way I can use my MIDI foot controller for the iPatch AND I can run any other devices by MIDI that I need to.

As for the name, I admit, I didn't think of it myself. My bassist came up with the moniker when I first started talking about the idea and it just stuck...
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  #2  
Old 11-19-2010, 07:59 PM
wabbitguy wabbitguy is offline
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The iPatch all lit up:



Mel
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  #3  
Old 11-20-2010, 03:11 PM
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John John is offline
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Thanks, Mel! This will be a blog post on Monday morning.
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Old 11-20-2010, 03:12 PM
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Also, what's the make/model of that enclosure?
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Old 11-20-2010, 10:06 PM
wabbitguy wabbitguy is offline
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Quote:
Originally Posted by John View Post
Also, what's the make/model of that enclosure?
That...as they say when they don't have a clue...is a VERY good question...

I bought it locally from one of the suppliers in the Vancouver (BC) area and it came unboxed so I have no idea who really makes it. Certainly there was no sticker or label on it:

RP Electronics - 1U Chassis

Like I said in the post, I could find lots of 10" or 12" deep 1U boxes, but trying to locate a 6" 1U was tough.

Also were I do do this again, I'd seriously consider using a 2U chassis, adding in the extra IN and OUT jacks, plus the MIDI THRU jack. I'd still probably try to stay with a 6" depth though. Having the holes drilled with a CNC setup, while adding substantial cost would be nice too...

Mel

Ah ha...the chassis is made by Middle Atlantic. Just found it...

Last edited by wabbitguy; 11-20-2010 at 10:09 PM.
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Old 11-29-2010, 01:52 PM
ethrbunny ethrbunny is offline
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Some questions:

1) why the additional relays? IE why use the MSA-R relays to switch a secondary set?

2) is the input buffer switchable? IE is it always in the signal chain? Do you notice a difference by using it?

3) where did you get the nifty sticker?

(caveat - Im not an electronics person - I can read a schematic but only just)
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  #7  
Old 11-29-2010, 07:10 PM
wabbitguy wabbitguy is offline
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Quote:
Originally Posted by ethrbunny View Post
Some questions:

1) why the additional relays? IE why use the MSA-R relays to switch a secondary set?

2) is the input buffer switchable? IE is it always in the signal chain? Do you notice a difference by using it?

3) where did you get the nifty sticker?

(caveat - Im not an electronics person - I can read a schematic but only just)
Good questions. Hope I can make the answers clear enough to understand...

1. The relays on the MSA-R are only single pole, single throw. Essentially an ON/OFF switch like a wall light switch. With a simple switch like this, all you could do would be to wire a single MSR-A relay from the input to the output:



As you can see, the pedal is still actively in the circuit so a "bypass" isn't possible.

If the MSA-R were a SPDT relay it would be closer to what would we need. Not perfect, but better. Many of the effects pedals on the market use this form of bypass. Even the ones with the foot switches that look like they "should" provide a true bypass (some of the EHX line for example):



If you look at that wiring diagram you see where the guitar input gets switched from the pedal IN to the signal path OUT. But this is also bad for the following reasons. The output of the pedal is still connected to the output of the signal path. If the pedal makes any noise at all, that is going to be audible.

Just as important is that the input to the pedal is left "floating". So the pedal is still active because it has a cable in it's input jack but it has no input signal. Try this with a high gain pedal and you'll find that it will fill up with noise, a delay pedal will be filling it's delay with noise and so on. And of course all this racket that you didn't generate from your guitar will be very evident on the output.

With the iPatch, we take a slightly different wiring and approach to the normal problems. First off, we use double pole, double throw relays (that's what is on those boards). This allows us to switch both the INPUT to the pedal and OUTPUT from the pedal:



I drew in the contacts above the terminal strips on those boards so you can see the wiring path. The relays are shown in their energized state. I drew two channels so you can see how one channel feeds through to the next (I have 8 channels so four boards)...

Lets look at the channel 1. Energized you can see the input goes to the send, the pedal output comes back in the return and that goes to the "output" or the next channel. If you de-energize the relays, the input goes straight to the output. But more important, the return is not in the circuit and the send (pedal input) is grounded (that upside down xmas tree is a ground symbol). Thus is nulled and completely removed from the signal path.

Something I should note, although I show a ground off the relays, the audio signal grounds are not grounded to the case I built it in. The only grounds are on the jacks. The case has a single ground point on the DC power supply.

2. The input buffer. There are two input jacks for the iPatch. One has the buffer in circuit, if you use the other jack, it removes the input and output from the buffer circuit. Does it work? It's kind of a yes it does and no it doesn't. It largely depends on your guitar, pickups, cables and pedals. If your guitar has low output pickups, or you don't typically pin the guitar volume control and play, then yes it will help. Some pedals like a decent signal at their input and work better that way as well. Provide them with a weak signal (Boss pedals like healthy input signals to keep the noise down) and they get all noisy on you. If you use 20 footer cables (of questionable quality), it really helps those...

If you do any recording, the buffer will be more important. In a live setting you can get away with a lot more noise than you'd ever do in a recording setup.

Hence, you have to experiment....there's no other way to find out what works best.

One of the revealing things about these switchers is that you can plug in a pedal, put the pedal in "bypass", and then use a true bypass like the iPatch to listen to the pedals "bypass" vs TRUE bypass. And in far too many cases you'll find that the pedals bypass robs an incredible amount of tone from your guitar. It'll go from bright and sparkling to dull and muddy as you switch it in and out. For my work, if the pedal isn't doing anything, it's not in the circuit.

One other slight "hiccup" that can bite you is if you have pedals active, and bypassed, then you enable them. You can get a "pop" in the signal path as the pedal connects itself. This is usually caused by the capacitors in the pedal and about the only way to "sort" of stop them is to put a 1 meg resistor across the return connection (or 2-4 meg as an experiment). It's not perfect when you have a pedal that acts up, but when dealing with poor pedal design in the first place, there's not much you can do.

3. The iPatch label...it's nothing fancy. I printed out a label on my colour laser printer, then used "double tack" mounting film to put it on. Although the patch looks like a city in the background, it's actually a photo of my pedalboard... The other labels are from a Brother P-Touch printer.

I guess I should mention that there are MANY pedal switchers on the market. Voodoo Labs GCX, Pedal Switcher, Loopzilla, Rocktron PatchMate 8, and more. Each of them is a little different but programmability is not one of their strong points. With the MSA-R, it is. That's the reason I decided to build my own. And even at that, I could really enhance it for "V2" if I feel the need.

Hope this explained it clear enough and if you have any other questions..ask away.

Mel
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Old 11-29-2010, 07:29 PM
ethrbunny ethrbunny is offline
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That was extremely informative! Thanks for putting your time into it.

I've been wanting to build a switcher essentially like what you have here. I use a looping pedal (BOSS RC-50) and an FX unit(TC GMajor) in the FX loop of my amp. In order to have different effects in said 'recording' and afterwards I need to have effects in front and behind the RC pedal. Also - being able to switch the routing in/out of the RC would be amazing. Looks like you've covered all of these.

Im duly impressed.

Can you ball-park your 'out of pocket' costs on this?
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Old 11-29-2010, 08:30 PM
wabbitguy wabbitguy is offline
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Quote:
Originally Posted by ethrbunny View Post
That was extremely informative! Thanks for putting your time into it.

I've been wanting to build a switcher essentially like what you have here. I use a looping pedal (BOSS RC-50) and an FX unit(TC GMajor) in the FX loop of my amp. In order to have different effects in said 'recording' and afterwards I need to have effects in front and behind the RC pedal. Also - being able to switch the routing in/out of the RC would be amazing. Looks like you've covered all of these.

Im duly impressed.

Can you ball-park your 'out of pocket' costs on this?
Ahh...yup...I ordered the MSA-R before they were released so I saved few bucks, I think the current one with the terminal strips is $59. So...here are the totals...

MSA-R - $59
Relay Boards (4) - $40
1/4" Mono Jacks (50) - $35
Stand offs (50 brass) - $7
LED Bezels (50) - $5
Middle Atlantic Rack Case - $65
DC 12VDC Regulated PS - $10
LED wiring connectors - $8
Input Buffer PCB - $8
Misc (transistor, resistors, switch, LED's etc) - $10
Everything else - priceless...

Note also the power supply I used is a "regulated" supply. Not your typical wall wart that tosses out 12V at "x"ma. It's regulated and gives out a rock steady 12V at up to 2A. The Boss power supplies (9Vdc) will actually output 11-12volts but will drop when under load.

Any way my total is roughly around the $250 mark. Also keep in mind that in several cases I only needed "x" number of parts, but when you find a good deal on eBay, you just buy a whack of them because they'll get used sooner or later.

And yep, eBay was the cheapest route to go for a lot of those parts. The single most costly item was the rack case itself. I wanted a 6" deep case and those are scarce. Middle Atlantic was the only company that made one I could find. And it's a premium buck. The relay boards were sort of pricey until you worked out what the parts and PCB's would have cost to make and then it just wasn't worth the time to do it myself.

The LED connectors are actually from my RC helicopters (they are used as battery connectors; called JST connectors). They just happen to be great to connect to standard headers for taking stuff "off board" from pin headers. I buy 10 of them at a time for $1.99 from HobbyKing.

Connect leads

When I started the project I figured it would run about $200-$300 by the time I'd be done. Comparing it to commercially available products, there were a few in that price range (Loopzilla for one), but a GCX or PatchMate were going to be a fair bit more. And again, less programmability. So now I can sell my VooDoo Labs pedal switcher because it's been replaced...

After using the iPatch for a while now, I can safely say there isn't anything I'd do differently. It's been rock solid and does everything I want. Granted I could still enhance it but I'm not sure that I'd be using the additional functionality any way so that could be pointless.

Oh and like a friend of mine used to say, if the idea of making anything yourself was to save money, don't start...

Mel
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Old 12-01-2010, 05:18 PM
domct203 domct203 is offline
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Nice project. Very well thought out and put together. I'm actually planning almost the same project but will be building my own DPDT relay boards.

FYI- Digi-Key has Aluminum 19" rack mount chassis. I used the 1U 19"X4" deep one for my MIDI Wah project using an MPA-100K (Details Here)
They're a little expensive but real easy to work with. They have 1U and 2U X8" deep and X 16" deep as well.

Here's a link to their interactive cataloge page. (Click Here)

Covers sold seperatly.

Dom
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Old 12-01-2010, 06:35 PM
wabbitguy wabbitguy is offline
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Quote:
Originally Posted by domct203 View Post
Nice project. Very well thought out and put together. I'm actually planning almost the same project but will be building my own DPDT relay boards.

FYI- Digi-Key has Aluminum 19" rack mount chassis. I used the 1U 19"X4" deep one for my MIDI Wah project using an MPA-100K (Details Here)
They're a little expensive but real easy to work with. They have 1U and 2U X8" deep and X 16" deep as well.

Here's a link to their interactive cataloge page. (Click Here)

Covers sold seperatly.

Dom
Hi Dom,

Thanks for the interactive catalog link! The 1U x 4" deep is slightly cheaper than what I paid for the 6" deep one, but the benefit is that it's not steel like mine (18 gauge aka the drill bit eater)...

I was also originally going to build my own relay boards and incorporate the 1/4" jacks right onto the board. At least until it dawned on me that I'd need two boards because I was going to have two rows of jacks (send/return). So one row would have been jacks on the boards, the other would have had all the switching circuitry.

What sort of stopped me from doing that was that I'd had to fix a couple of these switchers and getting those jacks out of the cases with the boards and wires, well, it was very time consuming. Fiddly work actually. It turned out that the supposed "Neutrik" jack that had the problem, wasn't a Neutrik at all and had split apart so the connection was intermittent.

So I decided to go with the solder lug style just from a servicing stand point.

I'd worked out the parts for my own relay board as well but I figured with my time to build, making the photo PCB (I only do photo resist boards), it wasn't cost/time effective. Thus I thought I'd take a chance on those ready made off shore ones. The relays I'd original priced out were way more than four of those boards.

If you have a source for miniature 12VDC gold plated relays that are reasonably priced that would be most useful.

I've tested the unit with my function generator and viewed the waveform at the various points on my scope looking for noise or artifacts in the signal. Even with the minimum signal injected and sweeping the typical frequency range, it's negligible. I figure my single coil pickups will be noisier...

What I'd also like to know is what type of waterslide decals you used for your MIDI-Wah.

Mel
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Old 12-01-2010, 07:13 PM
domct203 domct203 is offline
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Quote:
Originally Posted by wabbitguy View Post
What I'd also like to know is what type of waterslide decals you used for your MIDI-Wah.

Mel
I used clear waterslide decal paper for my Laser Jet printer. I get it in 8 1/2 X 11 sheets. I usually get it from www.decalpaper.com. It is available for inkjet printers as well, but the laser is easier and more durable.

Check out www.decalpaper.com for some videos on working with the waterslides, as well as searching the web. It really is an easy way to get some professional looking results. I find Laser Printers give the best results.

I use the printer when it is cold as recommended. I'll finalize all the decals on paper first, then I'll let the printer cool for an hour or so. I also cut the 8 1/2 X 11 sheet down to the size I need so I don't pass the decal sheet through the printer twice.

When using Laser Decal Paper, once the toner is dry you just soak them in warm water and apply.

When using the Inkjet Decal Paper you will need to seal the decals with clear acrylic spray first so (hopefully) the ink doesn't run in the water.

Also, you will see the edge of the clear decal, even if you use a setting solution like Solvaset, so you want to cut close to the edge of the printed image, or cover the entire surface with the decal (that's what I do with my Stomp Box Effects).



If you cut too close to the edge of the Inkjet decals you risk cutting too close and breaking the acrylic seal, allowing the ink to run in the water. No such worries with the Laser Decals.


Dom
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Old 01-07-2011, 01:14 PM
Jeff242 Jeff242 is offline
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Default Use for switching muliple amps?

I plan on "MIDIfying" my existing amp switcher and extending it from the current A/B loops to six doing something quite similar to this.
On my existing switcher, I switched the audio ground as well as the signal which requires a 3PDT relays if you also want to properly mute the non-live circuits.
Originally I actually didn't bother with the mute circuit as the second amp was always out of the circuit. It was only when I incorporated a third amp into the equation using a further two-way switch and a mixer that I spotted the noise problem so I added a third relay for the mutes.
So my question.. as I'm dealing with Amps rather than pedals all of which have their own chassis grounds etc., do you think it's wise to continue to switch the audio grounds as well as signal or do you think I'll get away with just switching the signal?
Cheers,
Jeff
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Old 01-07-2011, 06:12 PM
wabbitguy wabbitguy is offline
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Quote:
Originally Posted by Jeff242 View Post
I plan on "MIDIfying" my existing amp switcher and extending it from the current A/B loops to six doing something quite similar to this.
On my existing switcher, I switched the audio ground as well as the signal which requires a 3PDT relays if you also want to properly mute the non-live circuits.
Originally I actually didn't bother with the mute circuit as the second amp was always out of the circuit. It was only when I incorporated a third amp into the equation using a further two-way switch and a mixer that I spotted the noise problem so I added a third relay for the mutes.
So my question.. as I'm dealing with Amps rather than pedals all of which have their own chassis grounds etc., do you think it's wise to continue to switch the audio grounds as well as signal or do you think I'll get away with just switching the signal?
Cheers,
Jeff
There's a lot of stuff that comes into play here when using multiple amps as opposed to pedals. Hence what follows is information, food for thought. I use a Radial Twin City Bone switcher for my two amps now. It's not MIDI controlled but ultimately it doesn't need to be for my purposes.

There's two types of amp AB/Y switchers, passive and active. The normal is a a passive AB/Y switch for two amps, but when you want to incorporate three amps, it's going to take some careful design and you need to make sure your "roadie" has a good back. I've lugged two amps around for years and there is a point where...well...you know...(buy smaller amps)..

However, with multiple amps, comes multiple issues...

In a large percentage of the cases a passive switcher will work just fine. At least right up until you add some high gain pedals that themselves have a high noise floor, a mixer with a healthy gain stage that's noisy, or the ground loop that rears its ugly head.

And as you've found, isolating the grounds deals with the noise. To a point, but really that's only one of the issues to deal with.

The sometimes not so silent problem that creeps in is loading. If you run all three amps off the same signal at the same time, apart from more possible ground loop issues, you also shorted all three inputs of the amps together. That loads up the signal coming to them (they all want a piece of the pie) and typically you get a muddy signal. This also doesn't bode well for the last pedal that's driving them.

Once noise has been found, or the signal gets too ugly to use, then a passive ABCDEFGH/Y () is the only real solution.

There's scant few sources for anything beyond the typical AB/Y. VooDoo Labs makes a great 4 amp selector:

VooDoo Labs Amp Selector

If you read the manual about "how" the magic is done, you'll find that they use buffers and transformers. The buffers (or amp; as in opamps) boost the signal so there is no signal loss when driving all four amps, and the transformers isolate all the amps from each other. They also provide a ground lift for further isolation should it be needed.

The drawback is that this selector isn't exactly midi controlled. It could be if you want to hack into the switcher to do it. But that seems a little counter productive to me.

So if you really want to roll your own, then something like this buffered AB/Y would serve as a starting point for the amp selector design:



Notice it runs off two 9V batteries. That's typical for a lot of opamp designs so what they do is use a charge pump IC (something like a MAX1044A) to get the + and - voltages from a single 9V battery.

General Guitar Gadgets has a PCB that uses this design and it wouldn't be too hard to make a couple of these boards, then control these with a rely from an MSA.

AB/Y Switch

Ultimately you have to weigh all the pros and cons as I did with my iPatch.

Hope this helps some...

Mel
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Old 01-07-2011, 06:39 PM
Jeff242 Jeff242 is offline
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Hey Mel,
thanks for the reply. Great minds obviously do think alike as I've had the improved AB/Y circuit pinned to my wall for the passed couple of months and was thinking of incorporating parts of that circuit into my new switcher

I've been using various modelling setups direct into reference speakers for the past few years but now the kids are a little older and I've reclaimed some of my space back, I've dug out the old tube gear I used to use but I'm trying to keep some of the flexability that the modelling world allows: I hate tap dancing round loads of pedals, when I can hit the one button on my MIDI controller.
I only really plan to use a single amp at any one time and mostly just in my home studio setup. I run each amp into it's own load box, then a feed from there back to the switcher and then out to the FX (currently either a MIDIVerb 4 or the effects section of a PODXT Live). The outputs from the FX go to an ancient low power stereo tube power amp I reworked and then into the 4*12 speaker cab. So in theory I can have the tone of a flat out tube amp but at ear and neighbour friendly volumes.

Cheers,

Jeff
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Old 01-12-2011, 03:09 AM
trixdropd trixdropd is offline
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Ipatch looks awesome! I am the designer of Loopzilla and I use the msa-t to control it. Do you ever hear any clicks in the audio of the ipatch? How did you do the labeling on the rack? It looks killer. The work looks good mel.

As for a amp switcher, I make the Penta Switcher, a 5 amp switcher based off the hum free design rg has on his site. My friend Martin has told me my unit crushes his voodoo labs amp selector. So much so that he wants another of my units as a backup just in case. I could do the penta into a midi controlled design.

my website is www.championpedals.com if you want info on the penta switcher.

I love highly liquid products, and can't wait to buy more of them.
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Old 01-12-2011, 06:17 AM
wabbitguy wabbitguy is offline
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Quote:
Originally Posted by trixdropd View Post
Ipatch looks awesome! I am the designer of Loopzilla and I use the msa-t to control it. Do you ever hear any clicks in the audio of the ipatch? How did you do the labeling on the rack? It looks killer. The work looks good mel.

I love highly liquid products, and can't wait to buy more of them.
Hi,

Thanks for the nice comments. It seemed to take forever to get all the little bits and pieces and then in a couple of days, all done...I stuck it on my scope to see just how much noise I was carrying. I found a bit and found that having a single ground point for the power supply/audio/case took care of that in a hurry. I originally isolated the audio from the power and MSA but I was picking up some noise til I grounded the power supply to the single point (right at the output jack).

For clicks in the audio, I did have some and it took a bit to track it down. Turns out some pedals seem to have lousy decoupling capacitors. Or don't have any (worse). I tested methods of getting rid of the pop (click) and there's two ways I found to do it. One is to put a 1M resistor from across the RETURN jack, but the resistor works best when closest to the decoupling caps in the pedal. Alternately, I tried a 1M resistor across the input jack inside the pedal. This seems to work just as good and it means I can plug the pedal into the iPatch anywhere... I also tested resistors largely than 1M in the pedal input jack and really, anything 1M or larger works fine and doesn't alter tone.

I have a Reverb tank (tube driven) that doesn't like to be switched in and out. About half of the time I get pops when I do it. Since I completely rebuilding the studio right now, everything is in storage so I haven't had time to source that problem out.

For my labels I used a Brother P-Touch, white label tape and printed them out on a P-Touch 1500PC:



I should have probably spray a clear coat over the label, but unless you're at the right angle, you can't see the backing tape any way. I also used some wicked LED's (ultra bright) to get your mind off it. My idea was they'd be easy to see with any stage lighting and to that end, yep. They can hit you with a big spot and those LED's will punch through it. However on a dimply light stage, you actually light up the backdrop (or the drummer)...

As for Highly Liquid products, I find them Highly Addictive...

Mel
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  #18  
Old 05-17-2011, 12:46 PM
Longhair Longhair is offline
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Join Date: Feb 2011
Posts: 18
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Do you happen to have a schematic of your pedal switcher? It doesn't have to be in detail to where it includes the MSA-R and other off the shelf components - just how they are wired in and out.

I'm looking for ideas on doing my own switcher pedal that will be able to select betweeen amps and "float" rack effects. Float meaning 4 different things:
1) Bypass (guitar to amp)
2) Front Input (guitar to effect to amp)
3) Effects Loop Input (guitar to amp to loop out to effect to loop in)
4) Repeat above with second amp.

All controlled by MIDI foot pedal.

Thanks
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  #19  
Old 05-17-2011, 05:49 PM
wabbitguy wabbitguy is offline
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Quote:
Originally Posted by Longhair View Post
Do you happen to have a schematic of your pedal switcher? It doesn't have to be in detail to where it includes the MSA-R and other off the shelf components - just how they are wired in and out.

I'm looking for ideas on doing my own switcher pedal that will be able to select betweeen amps and "float" rack effects. Float meaning 4 different things:
1) Bypass (guitar to amp)
2) Front Input (guitar to effect to amp)
3) Effects Loop Input (guitar to amp to loop out to effect to loop in)
4) Repeat above with second amp.

All controlled by MIDI foot pedal.

Thanks
Check back a few posts and you'll see how I wired it with the relays from those boards I picked up. Beyond that, no, I don't have a schematic. Just the one in my head...

I've tried the amp switching with mine, on two of my amps it works fine, but on my other amp, there's a huge thump when I switch to it. Thus some loading issues at the amp. So switching during a song doesn't work well. I ended up using a Radial Twin City Bones to do it because designing the "be all and end all" typically turns into a large can of worms.

While your "float" ideas make the whole switching thing quite versatile, they also add a fair bit of complexity to it. And all the little problems that come with anything complex. I'd think it would take a fair bit of trial and error to arrived with a good working solution. You've moved way beyond just switching "relays".

I think you'd need those little buffers everywhere for each channels I/O so everything is loaded up. But that would be an experiment.

The closest unit I seen that might do what you want would be the Rocktron Patchmate series...but even that would need some testing out.

Mel
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  #20  
Old 05-17-2011, 06:31 PM
Longhair Longhair is offline
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Join Date: Feb 2011
Posts: 18
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Thanks for the advice.

I am using a G Lab Line Midi Switcher for the amp switching. They won't send the whole schematic so hopefully they can send me just the switching part so I don't have to open it up and void the warranty right away

I already tried finding a pre-built system and the closet thing that I found was the Voodoo Labs GCX Switcher - which looks like either a clone or improved Rocktron Patchmate. Just working the routing out on paper to make the rack effect float between 2 amps would have taken up half of the In/Out Send/Receive with a 4:1 Y Cable.

Since I don't know what I am doing - learning as I go - I am trying to make everything as simple as possible. Even if it doesn't work out, at least I would have tried
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