Hey, I'm not sure if this is the correct subforum for this, but I have a cheap Strat knockoff that I thought I might experiment with and add USB support. I was inspired by this: How to Build a USB Guitar. In that, he used a pre-built mic->usb converter, but the link is dead, and I'm guessing it's more than I want to pay because it comes with software as well. Plus, it looks like it's not that much more difficult to build one from scratch with the components available.
Now, I'll go ahead and admit that I'm a software guy, not a hardware guy, so I've never really done anything quite like this before, and I have a few questions. The first would be: does it even make sense to do this? The idea is to convert the information from the pickups to a digital format as quickly and as cleanly as possible so I can tinker with it in software.
Second question: Has anybody already done this and shared the schematics/how-to's and whatnot?
Third question: What components should I use? I've looked around a bit, and the TI PCM2900 (USB Audio - USB CODEC - PCM2900C - TI.com) looks like a pretty good candidate as it handles both the ADC and USB in a single chip. Would this be sufficient by itself in a reference circuit like this (Two-channel Analog-to-Digital converter board with USB interface), or would the signal need to be amplified. If it needs to be amplified, what's the best way to go about doing that?
Assume I know absolutely nothing about audio circuits (most likely accurate), so any tips on how to reduce noise, do proper grounding, etc. would be greatly appreciated!
Oh, and "Hi." I'm new here. I discovered this forum when searching around for the stuff I would need to do this, and it seemed like the ideal forum to register on and ask these kinds of questions.
Now, I'll go ahead and admit that I'm a software guy, not a hardware guy, so I've never really done anything quite like this before, and I have a few questions. The first would be: does it even make sense to do this? The idea is to convert the information from the pickups to a digital format as quickly and as cleanly as possible so I can tinker with it in software.
Second question: Has anybody already done this and shared the schematics/how-to's and whatnot?
Third question: What components should I use? I've looked around a bit, and the TI PCM2900 (USB Audio - USB CODEC - PCM2900C - TI.com) looks like a pretty good candidate as it handles both the ADC and USB in a single chip. Would this be sufficient by itself in a reference circuit like this (Two-channel Analog-to-Digital converter board with USB interface), or would the signal need to be amplified. If it needs to be amplified, what's the best way to go about doing that?
Assume I know absolutely nothing about audio circuits (most likely accurate), so any tips on how to reduce noise, do proper grounding, etc. would be greatly appreciated!
Oh, and "Hi." I'm new here. I discovered this forum when searching around for the stuff I would need to do this, and it seemed like the ideal forum to register on and ask these kinds of questions.
Go to Peavey.com and select PRODUCTS, then in the section labelled RECORDING see the Xport. Musicians Friend sells it for $60. It is a guitar/USB interface, and indeed comes with software. The software as far as I know is the peavey ReValver, which is pretty cool tube amp emulation that allows you to customize the amp circuits. And they throw in their Reaper DAW software.
Right next to that product is the Ampkit Link, an interface for guitar to iPhone and iPad. It also includes a bunch of apps. That sells for $30.
Right next to that product is the Ampkit Link, an interface for guitar to iPhone and iPad. It also includes a bunch of apps. That sells for $30.
The easy, cheap thing to do would be to take a Logitech (or other) desktop mic, bust it open, and build the bits into a guitar. I see a desktop usb mic on dealextreme for $4.99.
In that case you would glue the electret capsule to a resonating part of the guitar with a crystallizing type of glue (as opposed to rubbery) to get good sonic contact conduction.
If you wanted to get fancy, you could buffer the output from the magnetic pickup into the gubbins instead of the electret capsule. Electret mics usually have a built-in FET amplifier and might drive a load as low as 1k5 whereas a guitar (wound) pickup likes to see 250k.
In that case you would glue the electret capsule to a resonating part of the guitar with a crystallizing type of glue (as opposed to rubbery) to get good sonic contact conduction.
If you wanted to get fancy, you could buffer the output from the magnetic pickup into the gubbins instead of the electret capsule. Electret mics usually have a built-in FET amplifier and might drive a load as low as 1k5 whereas a guitar (wound) pickup likes to see 250k.
Hey, thanks for the responses. I have looked around at various prebuilt guitar->usb solutions, and that certainly would be the simplest route, but I kind of want to build my own just for the heck of it as a learning experience and to see what can be done on a minimal budget.
That said, the readily available guitar->usb solutions aren't out of the question, though if I do go with one, the question would be which one? Here are a handful of the ones I've seen:
Alesis GuitarLink
Rocksmith Real Tone Cable
Behringer UCG102 Guitar-to-USB Interface
Hosa 1/4 In USB Guitar Cable
Peavey Xport
M-Audio Fast Track USB
You suggested the Peavey Xport, but I haven't found much in the way of reviews on it. Have you used it? The Hosa sounds like a no-go because of sound quality. I'm actually leaning toward the Rocksmith cable. I could be off on this, but I imagine Ubisoft is trying to make money off of the game, not the hardware, and the hardware is likely more mass produced than other similar products, driving production costs down, so the quality/cost ratio might be higher.
The thought of using a USB mic had also crossed my mind. I have a USB Logitech mic which has surprisingly good quality, but it was $30 (same price as some dedicated guitar->usb adaptors). I also got a similar, but slightly less expensive, Rocketfish USB mic for a friend, and the quality was pretty bad. I'm not sure if it was the mic or the electronics, but I obviously don't want something that sounds bad. 🙂 Looking around on dealextreme, I see a handful of microphone->usb cables/adaptors and a ton of super cheap USB external sound cards with headphone jacks. I really have no idea which, if any of them, are worth trying.
Oh, and pardon my ignorance, but what do you mean by "gubbins"?
That said, the readily available guitar->usb solutions aren't out of the question, though if I do go with one, the question would be which one? Here are a handful of the ones I've seen:
Alesis GuitarLink
Rocksmith Real Tone Cable
Behringer UCG102 Guitar-to-USB Interface
Hosa 1/4 In USB Guitar Cable
Peavey Xport
M-Audio Fast Track USB
You suggested the Peavey Xport, but I haven't found much in the way of reviews on it. Have you used it? The Hosa sounds like a no-go because of sound quality. I'm actually leaning toward the Rocksmith cable. I could be off on this, but I imagine Ubisoft is trying to make money off of the game, not the hardware, and the hardware is likely more mass produced than other similar products, driving production costs down, so the quality/cost ratio might be higher.
The thought of using a USB mic had also crossed my mind. I have a USB Logitech mic which has surprisingly good quality, but it was $30 (same price as some dedicated guitar->usb adaptors). I also got a similar, but slightly less expensive, Rocketfish USB mic for a friend, and the quality was pretty bad. I'm not sure if it was the mic or the electronics, but I obviously don't want something that sounds bad. 🙂 Looking around on dealextreme, I see a handful of microphone->usb cables/adaptors and a ton of super cheap USB external sound cards with headphone jacks. I really have no idea which, if any of them, are worth trying.
Oh, and pardon my ignorance, but what do you mean by "gubbins"?
Ready made solutions are common and low cost, either specific guitar ones, mike ones, or just line input ones. Assuming you could source the dedicated IC's used at less cost than a complete unit, could you make the surfacemount double sided PCB required?.
You're right that the cost probably won't be much cheaper than a ready made solution, but, like I said, this would be a learning experience. Also, there's a lot of things I could tinker with. For example, I could map pickups to different channels and apply different effects (in software) per pickup, or do post-recording adjustments of pickup influences.
I don't think making a PCB would be necessary. The circuit doesn't seem like it would be that complicated, and I'm not planning to mass produce these things.
Has anybody built a USB microphone from scratch? Maybe that would be a good reference source.
I don't think making a PCB would be necessary. The circuit doesn't seem like it would be that complicated, and I'm not planning to mass produce these things.
Has anybody built a USB microphone from scratch? Maybe that would be a good reference source.
'gubbins' is a catchall expression like 'thingumabob', 'wotsit', 'doofer', more usually applied to an assemblage of thingumajigs meaning in this case 'everything apart from the electret mic'
Most poeple first electronics project generally isn"t a digital device .... I think you are reaching for something that is way beyond your abilities , while it"s great that you want to jump in feet first I believe you are trying to jump way past your ability ......
USB output is just useless on a guitar ...
you can't use asio because it only supports one device at a time, that means you have to use asio4all, and the (real) tot latency will be well over 30 ms, thus making playing thru computer effects unusable for any (half) serious player.
BUT
making an opamp buffer /preamp for each pickup is a good idea, you can connect the neck pickup to the left input and the bridge pickup to the right input of the soundcard, matching the input levels by setting gain individually to each pickup.
or adding spdif out is might be also usable, but there is really no point in adding digital out when you have free analogue inputs, as the analogue inputs are very good even in a mediocre outboard sound card.
so: usb out of the guitar is a little usless, and you have to use SMD components, and the results will be probably worse than connecting a guitar with an opamp amplifier into the line input jack, especially if you already have at least a medium quality sound card
you can't use asio because it only supports one device at a time, that means you have to use asio4all, and the (real) tot latency will be well over 30 ms, thus making playing thru computer effects unusable for any (half) serious player.
BUT
making an opamp buffer /preamp for each pickup is a good idea, you can connect the neck pickup to the left input and the bridge pickup to the right input of the soundcard, matching the input levels by setting gain individually to each pickup.
or adding spdif out is might be also usable, but there is really no point in adding digital out when you have free analogue inputs, as the analogue inputs are very good even in a mediocre outboard sound card.
so: usb out of the guitar is a little usless, and you have to use SMD components, and the results will be probably worse than connecting a guitar with an opamp amplifier into the line input jack, especially if you already have at least a medium quality sound card
I didn't suggest it "wouldn't be much cheaper", but rather that it would be MORE EXPENSIVE than buying one - assuming you could even source the chip.
And how does building your own make any difference to a commercial unit?, presumably you would just be using the exact same chip.
Presumably the chips are surfacemount only, so difficult to use without a suitable PCB.
If you really want to make your own, probably the easiest (and cheapest?) way to source a chip is to buy aready made unit, and remove the chip from it.
This could be fun, and nobody says that DIY is just to save money but .....
Of course you'll need a PCB, how else do you hold the ADC chip to the input buffer and USB driver and all the support components? Dead bug and nails in a board ain't gonna cut it for this project.
If I really had to do this myself, and I'm very much a hardware guy -not software, I'd grab some sort of USB mic and start hacking. There's got to be something with a half decent A to D in it (preferably with an available schematic, as hopeless as that is nowadays) and I'd just build an appropriate guitar in buffer. Probably have to work off the datasheet for the ADC.
I would imagine it's mostly in a single surfacemount chip, not separate chips.
I've just taken my Behringer USB sound 'card' to pieces, it uses a PCM2902, here's the datasheet
http://www.ti.com/lit/ds/symlink/pcm2902.pdf
If you google on that number there are some home made projects out there using the chip.
EDIT: It's not as dear as I feared, but still about half the price of a complete ready made unit - and that's just for the chip.
I was not aware of these limitations. Thanks for the info. Asio4all has always been a pain to use for me. Where did you get the 30+ms figure? I suppose that would be the equivalent of standing 10+m away from a speaker with no delay (just the sound travel time). I did a simple test using VSTHost and asio4all with a USB mic and an onboard Realtek sound card. I was able to set the buffer to the lowest setting, 64 simples, which I guess would be 1.3ms at 48khz + around 2ms for the VST plugin. Is there some kind of inherent 30ms delay on top of that? I didn't try anything to accurately measure the delay.
One problem I did notice with this setup was that after a minute or two, the sound would get all messed up -- almost like a sawtooth wave -- like the samples were getting jumbled around or something weird. Then, after another minute or two, it would clear up. The shorter I set the buffer, the sooner it happened. If I set it to 1024 samples, it might take like 5-10 minutes before it happened. I'm not sure if this was because of the USB mic or what. I'll have to experiment with some other devices. Pretty typical with my luck with Asio4all. :\
Should I decide to go this route, what would you recommend as far as components?
I don't have anything specifically designed for recording, so out of a built-in Realtek, a Sound Blaster X-Fi, and a Razer Barracuda AC-1 (rebranded C-Media CMI8788 aka OxygenHD), which would you recommend?
Mouser has tons of ADC's and other components available. This is the PCM2900 series chip I was talking about (16bit 8-48khz + USB):
PCM2900CDB Texas Instruments Audio CODECs
$7.35 (possibly free if you use TI's sample program)
This WM8786 one can do higher resolution (24bit 196khz), but doesn't have the USB support:
WM8786GEDS/V Wolfson Microelectronics Audio A/D Converter ICs
$3.48
I could get something like this: SSOP to DIP Adapter 20-Pin - SparkFun Electronics ($4).
Probably the easiest, but I don't know about the cheapest. Of course, realistically, we're likely only looking at maybe a $10 difference. Sure, there's a bunch of super-cheap USB sound devices that take a mic input, but it's almost impossible to figure out what chipsets they have and if those are any good. If you know of any good ones, let me know! On the other hand, there are some usb adaptors that use these < $10 components that sell for over $100.
I don't think making one is necessary. As in shelling out big bucks to have one custom-printed (I actually have no idea how much that costs. I imagine you need a large quantity to make it worthwhile). I could use a pre-built one like I linked above.
Yep, that's exactly the one I was talking about. I think the 2902 has spdif out in addition to the usb support. TI offers a pre-built reference board for this chipset, but it's over $100, which I found rather strange. Which Behringer device did you have, and how much was it?
UCA202, currently £19.20 from:
Blue Aran - Professional Sound and Lighting > Behringer > Computer > Interfaces
I tested my MXL Mic Mate USB Microphone Adapter with Asio4all, and it did not have the problem I previously described. I think that issue must be specific to the Logitech mic or the AK5370 chip in general. I popped open the mic mate to see what chip it has in it, but they actually scraped the surface of the chips off so you can't see what they are! I'm guessing it has one of the TI PCM2900 series chips based on the fact that it has both input and output (even though the device itself is only for a microphone), and it shows up as "USB Audio CODEC" ("USB audio codec" is the default string descriptor for that chip). It also has PID_2900 in the hardware id's. I'm guessing the other chip (there were only 2) was an opamp. I have no idea which one, though. I still need suggestions on what to use for amplification.
I also tried plugging the guitar into the mic jack on my onboard soundcard, but there was way too much noise. I'll have to try with a real sound card later. I haven't bothered putting a sound card in my newer computer yet.
I also tried plugging the guitar into the mic jack on my onboard soundcard, but there was way too much noise. I'll have to try with a real sound card later. I haven't bothered putting a sound card in my newer computer yet.
That's basically the same article I link in my first post. 🙂. I didn't want to purchase the whole m-audio software package to get that adaptor, and I don't know what components would be best for this, which is why I started the thread.
I finally installed my xfi and tried plugging the guitar into that, but the results weren't very good. There was a lot of interference and other noise, and the guitar sounded very muffled like most of the high frequencies were lost. I was able to set the asio delay down to like 2-4ms, though. Oddly, the buffer size needed to be larger. I'm not sure I fully understand how all of that works. I'd like to know more about the asio4all limitations. Does it have a set delay?
I finally installed my xfi and tried plugging the guitar into that, but the results weren't very good. There was a lot of interference and other noise, and the guitar sounded very muffled like most of the high frequencies were lost. I was able to set the asio delay down to like 2-4ms, though. Oddly, the buffer size needed to be larger. I'm not sure I fully understand how all of that works. I'd like to know more about the asio4all limitations. Does it have a set delay?
Not sure for that program but most ASIO and VST have settings where you can set buffer size, latency time etc .to optimize it, rather than use the defaults. What could happen when you force a low latency time, you can end up with signal dropouts and some other issues depending on your computer hardware, what software is processing the sound and available buffer memory.
- Status
- Not open for further replies.