diyAudio - Blog Entries
Go Back   Home > Forums > Blogs

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Old

General biking update...

Posted 29th April 2012 at 03:44 PM by chris661

After many months of riding and not cleaning my bike, I cleaned it.

It was considerably lighter after such a treatment, which was great when we (me and the college people) went up to Gisburn Forest for a ride around...

Note the pictures below aren't mine, but show where we went quite well...

Click the image to open in full size.

Click the image to open in full size.Click the image to open in full size.

Click the image to open in full size.

and, of course, here's a vid of someone else trying the black run.

hully gully (rollercoaster) gisburn 05-06-10 - YouTube

Some great riding there - if you're reading this, and happen...
chris661's Avatar
diyAudio Member
Posted in Uncategorized
Views 531 Comments 0 chris661 is offline
Old

Using Audacity to do NOS droop correction

Posted 29th April 2012 at 03:36 AM by abraxalito

If you have a NOS DAC (like a Metrum) and are curious to hear how it sounds with the zero-order hold corrected, here's a fairly simple way to try out my 3-tap filter using Audacity.

Load up the file you'd like to process and make two duplicates (select original and use Ctrl-D) - we'll call them A and B. We need to apply delay and gain to A and B which we do with Audacity's time-shift button (in the group of 6 tool buttons to the right of the transport buttons) and the 'Effects - Amplify' feature. A is shifted one sample to the right, and B, two samples right. I've shown how this looks with a mono chirp signal in the first image.

The gain is input into Audacity in dB so 0.15 becomes -16.5dB and 0.026 is -31.7dB. These are the gains for A and B, respectively. A needs to be inverted too - use 'Effects - Invert'. The second screen grab shows how it looks after these operations (I hid the device toolbar to give more space for waveforms).

Having processed...
Attached Thumbnails
Click image for larger version

Name:	audacity_NOS1.png
Views:	174
Size:	30.5 KB
ID:	654   Click image for larger version

Name:	audacity_NOS2.png
Views:	162
Size:	29.0 KB
ID:	655   Click image for larger version

Name:	audacity_NOS3.png
Views:	185
Size:	23.4 KB
ID:	656  
abraxalito's Avatar
diyAudio Member
Views 996 Comments 0 abraxalito is offline
Old

First measurement of NOS droop correction

Posted 27th April 2012 at 06:13 AM by abraxalito

Here's a ten discrete tone test waveform played back into my Sony PCM-M10 then FFT'd in Audacity with 512point FFT.

Audacity reports lower freq tones at -18.6dB and the highest (17.3kHz) at -18.9dB - a droop of 0.3dB. This might be in part my passive (LC) reconstruction filter which I have yet to characterize separately. So it appears to work
Attached Thumbnails
Click image for larger version

Name:	transversal_freq_resp.png
Views:	278
Size:	25.8 KB
ID:	650  
abraxalito's Avatar
diyAudio Member
Views 629 Comments 0 abraxalito is offline
Old

Hello world

Posted 26th April 2012 at 02:13 PM by ARIYAHOOR (های-فای و سیستم های استریو)

I'll start posting articles in Persian language, in hope of having Persian visitors
Banned
Posted in Uncategorized
Views 574 Comments 0 ARIYAHOOR is offline
Old

Flight of the Pheonix

Posted 26th April 2012 at 08:34 AM by rjm
Updated 4th May 2012 at 02:30 PM by rjm

Nor the remake, the original. Good film. Story shakes out something like "Twelve Angry Men in the desert": Put together a small, random group of people and pressure them to complete a task. In the case of "The Flight of the Pheonix" this is to make an airworthy plane (this one) from the crashed remains of another (this one).

So. We start with my old red Gainclone case, and a pair of these buffer boards , and a Takman resistor, 24 position stepped attenuator from eBay, unassembled, and start working to transform something old into something new.

Here's my LM3875 gainclone. Served me well, but it is time to bid adieu! (at least to the guts):
Click the image to open in full size.

Opened up, we see the circuit board, such that it is, and my home-built 11 position attenuator:
Click the image to open in full size....
Attached Thumbnails
Click image for larger version

Name:	DSC_4007 1280.jpg
Views:	148
Size:	236.8 KB
ID:	651   Click image for larger version

Name:	DSC_4009 1280.jpg
Views:	324
Size:	301.2 KB
ID:	652   Click image for larger version

Name:	DSC_4023 1280.jpg
Views:	242
Size:	291.4 KB
ID:	653   Click image for larger version

Name:	DSC_4073 1280.jpg
Views:	232
Size:	375.5 KB
ID:	663   Click image for larger version

Name:	DSC_4075 1280.jpg
Views:	116
Size:	309.4 KB
ID:	664  

Click image for larger version

Name:	DSC_4078 1280.jpg
Views:	216
Size:	367.6 KB
ID:	665   Click image for larger version

Name:	B-board 10e FFT.png
Views:	207
Size:	35.9 KB
ID:	670  
rjm's Avatar
rjm
diyAudio Member
Views 788 Comments 0 rjm is offline
Old

Stereo VSPS rev 50c

Posted 25th April 2012 at 12:48 AM by rjm

The original stereo VSPS project is now quite mature. I did a couple of minor tweaks on the last re-spin of the layout, removing the pads for the old Black Gate coupling caps (long gone), adding thermal isolation, and making room for a pair of optional ceramic bypass caps next to the op amp.

The new boards are matt black. Quite cool. I have a small stack if you need any.

All the info you need to build one is attached.
Attached Thumbnails
Click image for larger version

Name:	DSC_3986 1280.jpg
Views:	398
Size:	235.5 KB
ID:	644   Click image for larger version

Name:	pcb-vsps-50c.png
Views:	641
Size:	13.3 KB
ID:	645   Click image for larger version

Name:	pcb-vsps-50c-brd.png
Views:	921
Size:	10.2 KB
ID:	646   Click image for larger version

Name:	pcb-vsps-50c-sch.png
Views:	814
Size:	24.3 KB
ID:	647  
Attached Files
File Type: zip pcb-vsps50c.zip (83.0 KB, 261 views)
File Type: zip pcb-vsps50c-bom.zip (86.2 KB, 220 views)
rjm's Avatar
rjm
diyAudio Member
Views 1740 Comments 2 rjm is offline
Old

Custom building

Posted 21st April 2012 at 01:10 PM by jtktam (Newbie audio DIYer)

Last few months have been crazy with my day time job and with the custom builds I have taken up.

A water leak above my hobby work space caused a big headache. I had to sort through some of the boxes and trash tons of wet parts but now I am back in full swing

Lately there was some rumbling about ODAC being a commerical product etc.. I was caught in the crossfire trying to organize a groupbuy since the designer / manufacturer is local to me.

I have approach the admins about this and the "correct" way to get this going.. sucks trying to do people a service and get shot down with the rest of the violators

Looking to start a web site with pictures of my builds to try get more business.. this hobby is eating lots of my money and the excess parts is taking up too much space
diyAudio Member
Posted in Uncategorized
Views 742 Comments 1 jtktam is offline
Old

Flattening the NOS droop

Posted 14th April 2012 at 03:13 AM by abraxalito
Updated 14th April 2012 at 03:48 AM by abraxalito

Having been a fan of NOS DACs now for something over a year I've decided it was high time for sorting out their most serious drawback - the roll off in the HF. This is an unavoidable result of using a zero-order hold function to reconstruct the original (impulse) samples. Droop exists even with oversampled DACs, its just at its most severe in NOS.

One of the most popular ways to flatten the response is to add on some kind of analog filter with a rising response (to 3.16dB @ 20kHz). A first order shelving filter can't quite cut it though so an LC tank circuit has been employed by a few. This needs to have a moderately high Q to achieve the correction.

I've played around with inductors to achieve this and haven't much liked the resulting sound. Whether this was due to the particular inductors I was using I didn't experiment. Admittedly they were very cheap ones. In general though when I've used high Q circuits in crossovers I haven't much liked the colouration...
abraxalito's Avatar
diyAudio Member
Views 1060 Comments 4 abraxalito is offline
Old

X-reg Evaluation Boards

Posted 7th April 2012 at 12:15 AM by rjm
Updated 9th April 2012 at 03:37 AM by rjm

Once in a while I get emails asking after the X-reg evaluation boards. These are handy little 5x8 cm test boards for the X-reg voltage regulator - or they would be, if I had ever bothered to get a set made.

Since the circuit is built into the VSPS300 and Phonoclone 3, it wasn't really a big priority.

Anyhow, yesterday I re-drew the evaluation boards and I'll be getting a batch made in the near future, along with some of the stereo VSPS that people were also asking after recently. They won't exactly fly off the shelves, but I started to feel bad for those few people who actually wanted them.
Attached Thumbnails
Click image for larger version

Name:	pcb-xreg-15c-brd.png
Views:	698
Size:	10.3 KB
ID:	640   Click image for larger version

Name:	pcb-xreg-15c.png
Views:	759
Size:	11.0 KB
ID:	641   Click image for larger version

Name:	pcb-xreg-15c-sch.png
Views:	732
Size:	22.2 KB
ID:	642  
Attached Files
File Type: zip pcb-xreg.zip (129.5 KB, 244 views)
rjm's Avatar
rjm
diyAudio Member
Views 1217 Comments 0 rjm is offline
Old

Recycling?

Posted 2nd April 2012 at 08:37 PM by DigitalJunkie

So,one of the monitors I use decided to die yesterday,it came back from standby,but had rainbow lines all over the screen..Something in the TFT panel itself,COF or something.Gaw.

Anyways,it had built in sound,using a TDA7496L chip for the amp..I got to looking at it,and decided to pull it off the PCB and build a (headphone)amp with it.

It's basically the schematic on the datasheet,with slightly larger input and output caps,and it's all powered by a 3-cell Li-ion pack for a Vcc of about 11-12V.

Here's the datasheet.
http://www.st.com/internet/com/TECHN...CD00001216.pdf

It doesn't sound tooo bad,really. It's not the best thing ever,but for a couple hours of tinkering with junk that was on the bench, I'm pleased.
It's got more than enough power for 'phones,some care needs to be taken to prevent any accidents.

So yea,yesterday was more or less; Troubleshoot monitor,discover...
diyAudio Member
Posted in Uncategorized
Views 905 Comments 3 DigitalJunkie is offline
Hide this!Advertise here!

New To Site? Need Help?

All times are GMT. The time now is 09:06 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2