Recent Posts

Pages: 1 ... 8 9 [10]
91
PreenFM2 / Re: Preenfm2 with Roli Seaboard
« Last post by lokki on November 16, 2017, 04:27:30 PM »
well yes me :-)

it is very simple on the preenfm:

if you enable global midi channel in the menu any message from this channel will be spread to all voices.

92
PreenFM2 / Preenfm2 with Roli Seaboard
« Last post by minoki on November 16, 2017, 03:39:10 PM »
Hi,

i just received a Roli Seaboard MPE keyboard and i was wondering if anybody had experience with the last Preenfm firmware and the potential MPE functionnality.
93
PreenFM2 / Re: Subtle distortion on one channel
« Last post by clĂ©ment on November 16, 2017, 01:35:26 AM »
Hi there, I believe I was referring to the same issue here.
In my case I notice it mainly when I'm working on "soft" sounds, not with strong FM. Is it the same for you?
94
PreenFM2 / Re: Subtle distortion on one channel
« Last post by Xavier on November 15, 2017, 11:01:05 PM »
Each channel is the sum of 2 Dac outputs (12 bits + 6 bits).
The resistors pair 115K and 1.8K have a ratio of 63.88 (6 bits = 64) which is what is used in the sum.

You can verify with a multimetter that you mesure the same value on the 2 115K and the same on the 2 1.8K.
You'll get a lower value for the 115 because of the other components in the circuit.

(You can verify the same thing for all the paired resistors around the op amp, they are all part of the output audio.)
95
PreenFM2 / Re: PreenFM2 SMD version
« Last post by Xavier on November 15, 2017, 10:41:35 PM »
Xavier, do you think the design I'm doing will be of any interest?

This is a great project. But i'm not sure who the target is...
96
PreenFM2 / Re: PreenFM2 SMD version
« Last post by lokki on November 15, 2017, 10:26:29 PM »
two stereo jacks would be awesome...
97
PreenFM2 / Re: PreenFM2 SMD version
« Last post by zelea2 on November 15, 2017, 07:59:05 PM »
i would wish there were 4 outputs instead of only stereo so that you could route each instrument to another channel. but that is not gonna happen without adjusting quite a lot of the firmware and i am also not sure if the stm32 would support another stereo dac for the additional outs.

The STM32F4 has two I2S interfaces and the PCM5102 are cheap and in small packages. One problem is the size of the 6.3mm sockets; there is not enough room for 4 of them so I'll have to switch to two 6.3mm stereo sockets instead.  But as you said the main problem is the firmware support.

Xavier, do you think the design I'm doing will be of any interest? I will publish a diff file with the changes of the git firmware (mainly using #ifdef's for the differences). Should I bother to ground one currently  unused STM32 pin so the future firmwares could distinguish between my hardware design and yours?
This will be just to report on the LCD that you are not using the correct firmware for the board and stop the code from running.
98
PreenFM2 / Re: Subtle distortion on one channel
« Last post by SirPrimalform on November 15, 2017, 03:47:55 PM »
Good idea, will try and do that this evening.
99
PreenFM2 / Re: Subtle distortion on one channel
« Last post by lokki on November 15, 2017, 03:03:50 PM »
can you record a file and create a spectrogram of both channels to compare? are both channels set to exactly the same sound? i.e. a mono sound centered?
100
PreenFM2 / Subtle distortion on one channel
« Last post by SirPrimalform on November 15, 2017, 01:50:12 PM »
My PreenFM2 seems to have a subtle distortion on one side of the stereo image. It doesn't sound like clipping, but rather that kind of digital distortion you get when the steps in the DAC aren't quite the same size. I've ignored it for a long time as it's very subtle and I rarely use it in stereo but I'd like to diagnose it now if I can.

Can anyone suggest any steps? Swapping the DAC ICs would be an obvious one... see if the distortion follows the DAC or not.
Pages: 1 ... 8 9 [10]