21 May
2025
21 May
'25
5:23 p.m.
There are lots of guitar to USB audio devices out there and it seems they
have all done them wrong. I modified one of them and it actually sounds
very good. Perhaps better than plugging into the "high impedance" input of
many audio interfaces or using a DI box into a mic input. The result is a
much more open sound in particular with single coil pickups (or tapped as
I happen to have).
Why do I think they have likely all done them wrong? The Application notes
say: "Please follow the reference schematic for microphone section
design." So not only is it easy but it is recomended. I am sure it works
well for a computer mic.
Anyway, for those who want a good quility direct to usb guitar cable here
is my journey to fix a toy into something better.
https://www.ovenwerks.net/hardware/GuitarUSBhack/index.html
I find it amazing that the manufactures would not reduce their parts count
while making a better product.
Len
--
Len Ovens
www.ovenwerks.net
21 May
21 May
6:06 p.m.
On Wed, 21 May 2025 08:23:05 -0700 (PDT)
Len Ovens <len(a)ovenwerks.net> wrote:
There are lots of guitar to USB audio devices out there
and it seems they
have all done them wrong. I modified one of them and it actually sounds
very good. Perhaps better than plugging into the "high impedance" input of
many audio interfaces or using a DI box into a mic input. The result is a
much more open sound in particular with single coil pickups (or tapped as
I happen to have).
Why do I think they have likely all done them wrong? The Application notes
say: "Please follow the reference schematic for microphone section
design." So not only is it easy but it is recomended. I am sure it works
well for a computer mic.
Anyway, for those who want a good quility direct to usb guitar cable here
is my journey to fix a toy into something better.
https://www.ovenwerks.net/hardware/GuitarUSBhack/index.html
I find it amazing that the manufactures would not reduce their parts count
while making a better product.
Len
--
Len Ovens
www.ovenwerks.net
Thanks for that. Very interesting and quite easy to do!
--
Will J Godfrey {apparently now an 'elderly'}
10:46 p.m.
On 5/21/25 06:06, Will Godfrey wrote:
On Wed, 21 May 2025 08:23:05 -0700 (PDT)
Len Ovens <len(a)ovenwerks.net> wrote:
Thanks for the explanation. It's not something I'd consider easy to do,
my soldering/electronics skills aren't up to that!
A friend gave me a DI box that has amp modeling and other capabilities,
but it does have one feature I've used many times. Gain control. Plug
the guitar into it's guitar input, leave everything else at neutral (no
amp modeling), and adjust gain until it's output is right for line input
to my little USB card.
I bought a contact mic for the guitar that outputs electric guitar
levels but haven't tried it yet with my classical guitar. I wonder what
a classical guitar might sound like going through Guitarix?
--
David W. Jones
gnome(a)hawaii.rr.com
authenticity, honesty, community
http://dancingtreefrog.com
"My password is the last 8 digits of π."
There are lots of guitar to USB audio devices out
there and it seems they
have all done them wrong. I modified one of them and it actually sounds
very good. Perhaps better than plugging into the "high impedance" input of
many audio interfaces or using a DI box into a mic input. The result is a
much more open sound in particular with single coil pickups (or tapped as
I happen to have).
Why do I think they have likely all done them wrong? The Application notes
say: "Please follow the reference schematic for microphone section
design." So not only is it easy but it is recomended. I am sure it works
well for a computer mic.
Anyway, for those who want a good quility direct to usb guitar cable here
is my journey to fix a toy into something better.
https://www.ovenwerks.net/hardware/GuitarUSBhack/index.html
I find it amazing that the manufactures would not reduce their parts count
while making a better product.
Len
--
Len Ovens
www.ovenwerks.net
Thanks for that. Very interesting and quite easy to do!
22 May
22 May
12:36 p.m.
On May 21, 2025 10:46:24 PM GMT+02:00, david <gnome(a)hawaii.rr.com> wrote:
On 5/21/25 06:06, Will Godfrey wrote:
Sorry for top-posting. Phones suck ;)
Here's another "trick" that often enough works great: Use any _buffered_
guitar pedal in front of a line level input. Boss tuners or (pure) boost pedals are good
for this. Especially uf they are _not_ true bypass, i.e. the bypass goes through the
buffer. The buffer usually has enough juice on its output side to drive the low impedance
line-in.
The difference to going straight from the guitar is like day and night :) And having a
gain knob on a boost pedal is handy as well!
Regards,
FPS
On Wed, 21 May 2025 08:23:05 -0700 (PDT)
Len Ovens <len(a)ovenwerks.net> wrote:
Thanks for the explanation. It's not something I'd consider easy to do, my
soldering/electronics skills aren't up to that!
A friend gave me a DI box that has amp modeling and other capabilities, but it does have
one feature I've used many times. Gain control. Plug the guitar into it's guitar
input, leave everything else at neutral (no amp modeling), and adjust gain until it's
output is right for line input to my little USB card.
I bought a contact mic for the guitar that outputs electric guitar levels but haven't
tried it yet with my classical guitar. I wonder what a classical guitar might sound like
going through Guitarix?
There are lots of guitar to USB audio devices out
there and it seems they
have all done them wrong. I modified one of them and it actually sounds
very good. Perhaps better than plugging into the "high impedance" input of
many audio interfaces or using a DI box into a mic input. The result is a
much more open sound in particular with single coil pickups (or tapped as
I happen to have).
Why do I think they have likely all done them wrong? The Application notes
say: "Please follow the reference schematic for microphone section
design." So not only is it easy but it is recomended. I am sure it works
well for a computer mic.
Anyway, for those who want a good quility direct to usb guitar cable here
is my journey to fix a toy into something better.
https://www.ovenwerks.net/hardware/GuitarUSBhack/index.html
I find it amazing that the manufactures would not reduce their parts count
while making a better product.
Len
--
Len Ovens
www.ovenwerks.net
Thanks for that. Very interesting and quite easy to do!
6:44 p.m.
On Thu, 22 May 2025, Florian Paul Schmidt wrote:
Here's another "trick" that often enough
works great: Use any _buffered_
guitar pedal in front of a line level input. Boss tuners or (pure) boost
pedals are good for this. Especially uf they are _not_ true bypass, i.e.
I was doing that very thing before I modified my interface ;)
However, my purpose for getting the USB cable in the first place was to
be able to practice without an amp, pedals, many cables, an extension cord
with extra outlets, wall warts, etc. Just plug into the computer that is
already sitting there, run guitarix or somme other effects chain and go.
I think if I was recording, I would A) Mic the cab (I have a limited
selection of mics though) or B) use a direct out from my amp. This would
still need some speaker modeling at least but would be easier.
the third option would be guitar direct either through the board or some
other preamp. However, I don't have a computer that can run a whole lot of
effects and stuff at low latency so I could monitor in realish time. I am
less than happy with complete guitar signal chain in the computer anyway.
Might be my inability to set it up right but I like my analog chain.
Len
--
Len Ovens
www.ovenwerks.net
21 May
21 May
10:40 p.m.
On Wed, May 21, 2025 at 08:23:05AM -0700, Len Ovens wrote:
Why do I think they have likely all done them wrong?
The Application notes
say: "Please follow the reference schematic for microphone section design."
So not only is it easy but it is recomended. I am sure it works well for a
computer mic.
Many manufacturers will just copy the application note circuit.
The reason is that good analog audio designers are rare (and
expensive).
Even as mic input that circuit is strange. R10 (8k2) in series with
the input ? It may be there for protection (together with the varistor),
but otherwise it just adds noise.
Anyway, for those who want a good quility direct to
usb guitar cable here is
my journey to fix a toy into something better.
https://www.ovenwerks.net/hardware/GuitarUSBhack/index.html
Removing the DC bias is of course a good idea. But I don't think
the resulting input impedance will be anywhere near to 1M. Together
with C11, 1M would form a 1.6 Hz highpass. In other words, if the
chip input impedance were really around 1M then C11 could (and
should) be smaller.
Now even if the resulting input impedance is lower than what
a typical guitar amp input would provide, that shouldn't be a
big problem. You will just need some EQ to compensate, and the
volume control on the instrument may 'feel' different.
Then there's C18, no value given. It will resonate with the
pickup inductance at some frequency, so it may be interesting
to experiment with.
Ciao,
--
FA
22 May
22 May
4:29 a.m.
On Wed, 21 May 2025, Fons Adriaensen wrote:
Removing the DC bias is of course a good idea. But I
don't think
the resulting input impedance will be anywhere near to 1M. Together
with C11, 1M would form a 1.6 Hz highpass. In other words, if the
chip input impedance were really around 1M then C11 could (and
should) be smaller.
That makes sense. I was thinking the input element would probably be a FET
but really the manufacture offers no spec on input impedance.
Now even if the resulting input impedance is lower
than what
a typical guitar amp input would provide, that shouldn't be a
big problem. You will just need some EQ to compensate, and the
volume control on the instrument may 'feel' different.
It certainly sounds better than it did before. I don't do volume fades so
may not notice feel. The lack of switch pops and scratchy pot sounds makes
it worth while.
Then there's C18, no value given. It will resonate
with the
pickup inductance at some frequency, so it may be interesting
to experiment with.
It says 101 which should be 100pf. Guitar pickup coils could be anywhere
from 5 to 20k and the volume pots are 500k (in my case) 250k for single
coil guitars.
Thank you for your input
--
Len Ovens
www.ovenwerks.net
10:46 a.m.
On Wed, May 21, 2025 at 07:29:51PM -0700, Len Ovens wrote:
I was thinking the input element would probably be a
FET
Unlikely for a mic input. As long as Zin is a few kOhm it
would be OK.
Some (much more expensive) mic preamps use a 1:5 or 1:10
transformer followed by a FET. That can work really well.
It says 101 which should be 100pf. Guitar pickup coils
could be anywhere from 5 to 20k
That would be DC resistance, which is not very relevant.
When the volume pot is fully up you have C11 + cable
capacitance in parallel with the *inductive* impedance of
the pickup. That will result in a resonance peak damped
only by the volume pot and preamp input impedance.
This is the main reason why different cables may have
there own 'sound'.
Ciao,
--
FA
12:57 p.m.
Len Ovens <len(a)ovenwerks.net> writes:
There are lots of guitar to USB audio devices out
there and it seems
they have all done them wrong. I modified one of them and it actually
sounds very good. Perhaps better than plugging into the "high
impedance" input of many audio interfaces or using a DI box into a mic
input. The result is a much more open sound in particular with single
coil pickups (or tapped as I happen to have).
Why do I think they have likely all done them wrong? The Application notes
say: "Please follow the reference schematic for microphone section
design." So not only is it easy but it is recomended. I am sure it
works well for a computer mic.
Anyway, for those who want a good quility direct to usb guitar cable
here is my journey to fix a toy into something better.
https://www.ovenwerks.net/hardware/GuitarUSBhack/index.html
I find it amazing that the manufactures would not reduce their parts
count while making a better product.
You could go the opposite way: scavenge a cheap electret microphone
capsule for its FET and put it in your guitar cable (with a small DC
blocking capacitor) as a source follower at the guitar end.
That would provide the guitar with super-high impedance while making the
connection quite impervious to noise. Also uses the interface chip and
circuitry as intended by the manufacturer.
And you don't need to mess with the "guitar to USB audio" device.
--
David Kastrup
1:01 p.m.
Len Ovens <len(a)ovenwerks.net> writes:
Anyway, for those who want a good quility direct to
usb guitar cable
here is my journey to fix a toy into something better.
https://www.ovenwerks.net/hardware/GuitarUSBhack/index.html
I find it amazing that the manufactures would not reduce their parts
count while making a better product.
I consider it pretty likely that their "part count" is 1, namely the
complete mass-manufactured circuit with PCB and parts.
--
David Kastrup
14
days inactive
15
days old
linux-audio-user@lists.linuxaudio.org
9 comments
6 participants
participants (6)
-
david -
David Kastrup -
Florian Paul Schmidt -
Fons Adriaensen -
Len Ovens -
Will Godfrey