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New PSU-4448mk2 Power Supply Kit for Yamaha PM1000 modules (adjustable output voltages)
More TS-2 Battery Testing
TS-2 Prototype Working!!!
TS-2 Mic Preamp - Testing & Working!
TS-2 Mic Preamp - Motherboard
TS-2 Mic Preamp - Switchboard Prototype
TS-2 Mic Preamp Prototype PCBs
Audio Testing of new SC-1 Solo prototype.... SUCCESS!!!
DIY DC-DC Converter PSU working!
New PCB for SC-1 Solo Mic Pre Kit + DC-DC Converter PSU
SC-1 Solo Preamp (Prototype) powered by 12VDC wall wart (or battery)
DC to DC Switching PSU (12Volts to +/- 18V & 48V)
Mic Preamp SC-1 with Cinemag input/output transformers
ATI X800XT Fan Upgrade for Mac G5
DC to DC Switching PSU (12Volts to +/- 18V & 48V)
IO-Module Prototype #002 Testing
Mini-IO PCBs are here!!!!
CNC Machine
SC-1 Preamp + IO-Module
Oscilloscope photos and audio samples ... DCC-1848

Archive

October, 2008 (1)
September, 2008 (1)
August, 2008 (5)
July, 2008 (6)
June, 2008 (2)
May, 2008 (1)
April, 2008 (1)
March, 2008 (2)
February, 2008 (2)
January, 2008 (3)
December, 2007 (5)
November, 2007 (7)
April, 2007 (10)
March, 2007 (3)
February, 2007 (3)
January, 2007 (11)
December, 2006 (11)
November, 2006 (11)

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SC-1 Mic Preamp NOW ON SALE!!!!

After many months of development, testing, troubleshooting, frustration, problems, and accomplishments... the SC-1 mic preamp kit, PSU-1848 power supply kit and power transformer kits are now available for sale!

Click here to ORDER

Photo of a finished SC-1 mic preamp kit!  (Note: XLR jacks and wires shown on picture not included in the kit.)

Features:
- Low-Noise, transformerless, High-Quality Mic Preamp
- All solid-state design, using chipsets from THAT Corp and Burr-Brown
- Soft-start, slow ramp-on +48V phantom power
- Crystal clear Red LED indicator for phantom power
- Electronically balanced input and output stages
- 12-position Grayhill gain selector switch
- Gain range from +6 to +72dB, in 6dB increments
- Input RFI protection
- Input clamping protection
- Output surge protection circuit
- Output RFI protection
... read more...

Download PDF file of Assembly Guide/Kit Instructions

Related products like the PSU-1848 Power Supply Kit, Power Transformer Kit, Power Control Kit are also available for sale. Click here.
 Thursday, August 07, 2008
New PSU-4448mk2 Power Supply Kit for Yamaha PM1000 modules (adjustable output voltages)
Thursday, August 07, 2008 6:57:06 PM (Central Daylight Time, UTC-05:00) (  |  |  |  )
Newly redesigned, improved, PSU-4448mk2 Kit!

Now, both rails are adjustable via onboard trimmers for that 100% perfect voltage setting.
Also two on-board LEDs... which you can wire to your front panel to use as a POWER ON indicator.
100% more filtering. More capacitors for ripple filtering.
Standard 0.1" pad spacing so you can use standard 0.1" headers.



Comments | Trackback | # 
 Thursday, July 31, 2008
More TS-2 Battery Testing
Thursday, July 31, 2008 5:59:37 AM (Central Daylight Time, UTC-05:00) (  |  )
Tested the other channel on the preamp board... oh yeah... it works! Smile

Now, time to do some burn-in testing.

BATTERY TESTING Part Deux...
Hooked up the 2-ch pre to a Tekkeon battery... run some music signal and listened to it on my monitors... everything connected using test clips. What's the current consumption of the preamp? (i.e. with the VU Meters turned off)

* You can see which LED is lit up on the Tekkeon battery which designates the output voltage selected.

TESTING AT 12VDC ... of course no surprise here, it will work


MAX voltage input is 14VDC...


Okay, no surprises there...

Just for kicks... I decided to lower the input voltage to see how it holds up... At what point will the sound disappear and the pre stops working?

Let's try 9Volts... still works.



How about 6Volts... surely it will drop at 6Volts... but nope, it's still working.


This is disappointing... ;D Let's try 4.5Volts input... That should kill it!

Nope... still working...

Okay, the lowest setting on the Tekkeon battery is 3 Volts... let's kill this pre, die die die.


Unfortunately, it's still working. Sound is still coming out of the pre. I've been listening for the past half-hour with the pre running on 3Volts from the battery and no problemo. It's still going.

Nothing feels hot. Not the battery, not the preamp, not the various chips, not the PSU section. Everything is C.o.o.l!

Sooooo, you can say I'm pretty pleased about the results.

PS: Notice my new multimeter? Yep... It's a Fluke, baby ;D

Comments | Trackback | # 
 Monday, July 28, 2008
TS-2 Prototype Working!!!
Monday, July 28, 2008 5:58:31 AM (Central Daylight Time, UTC-05:00) (  |  |  )
Finally finished one channel and did some testing.... THE MOMENT OF TRUTH is coming! Will it work or not???

Woohoooo!!!!! YES! Smile Smile Smile

At first I wasn't getting any signal and was in a bit of panic... I'm thinking "oh no... what did I do wrong?"

Told myself I need to calm down and re-check everything step by step. Found out I have a loose connection since everything is just temporarily affixed with tape and alligator clips. Secured that connection and now we have continuity.

Device Under Test
Working properly and great.... and powered from a 12VDC power source, wall wart or battery.


Then I heard music... coming from my signal source... YES! It works and passes signal. Sounds good too! Pretty stoked about it. Check the gain settings, it works... check the trim, it works. I tested it with a line level input and an SM57 dynamic mic, and yes, sounds great. I haven't tested it yet with condenser mics since I don't have the switchboard hooked up yet... (the switchboard has the 48V phantom power converter).

After an hour of music listening, hooked it up to my signal gen and oscilloscope to see out how things are.

Check it out... here's the square wave response at 1Khz. Notice how clean and sharp the square wave response is... no ringing, oscillations or instability at either the rising and falling edges!

Square Wave Response 1Khz
Super sharp square wave response. Nice audio quality.


Did some output measurements while we're at it... how high an output can we go before clipping or instability. I'm not expecting it to be high (like +27/28dBu) since we're not using high supply voltages here, just a DC-DC converter PSU... but let's see what can we get...

Not bad.... not bad at all. Some readings....

15Hz @ 32Vpp = +23 dBu
20Hz @ 35.6Vpp = +24dBu
1Khz @ 37.7Vpp = +24.7 dBu
22Khz @ 31.1Vpp = +23dBu
100Khz @ 24.4Vpp = +20dBu
200Khz @ 14.65Vpp = +16.5dBu

Output waveform at 100Khz.



What's the Next Step?

Build the 2nd channel on the TS-2 preamp board, then test together the Motherboard and Switchboard...
Metalwork/CNC for the case, verify measurements and hole locations

So far, I'm pretty pleased with how everything is working out, from concept and design on paper, to CAD, to a working prototype.

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 Sunday, July 27, 2008
TS-2 Mic Preamp - Testing & Working!
Monday, July 28, 2008 3:24:50 AM (Central Daylight Time, UTC-05:00) (  |  |  )

Finally finished one channel and did some testing.... THE MOMENT OF TRUTH is coming! Will it work or not???

Woohoooo!!!!! YES!  Grin Grin Grin

At first I wasn't getting any signal and was in a bit of panic... I'm thinking "oh no... what did I do wrong?" 

Told myself I need to calm down and re-check everything step by step. Found out I have a loose connection since everything is just temporarily affixed with tape and alligator clips. Secured that connection and now we have continuity.

Device Under Test


Then I heard music... coming from my signal source... YES! It works and passes signal. Sounds good too! Pretty stoked about it.  Check the gain settings, it works... check the trim, it works.  I tested it with a line level input and an SM57 dynamic mic, and yes, sounds great.  I haven't tested it yet with condenser mics since I don't have the switchboard hooked up yet... (the switchboard has the 48V phantom power converter).

After an hour of music listening, hooked it up to my signal gen and oscilloscope to see out how things are. 

Check it out... here's the square wave response at 1Khz.  Notice how clean and sharp the square wave response is... no ringing, oscillations or instability at either the rising and falling edges!

Square Wave Response 1Khz


Did some output measurements while we're at it... how high an output can we go before clipping or instability. I'm not expecting it to be high (like +27/28dBu) since we're not using high supply voltages here, just a DC-DC converter PSU... but let's see what can we get...

Not bad.... not bad at all.  Some readings....

15Hz @ 32Vpp      = +23 dBu
20Hz @ 35.6Vpp   = +24dBu
1Khz @ 37.7Vpp    = +24.7 dBu
22Khz @ 31.1Vpp   = +23dBu
100Khz @ 24.4Vpp = +20dBu
200Khz @ 14.65Vpp = +16.5dBu

Output waveform at 100Khz.



What's the Next Step?

Build the 2nd channel on the TS-2 preamp board, then test together the Motherboard and Switchboard...
Metalwork/CNC for the case, verify measurements and hole locations
 
So far, I'm pretty pleased with how everything is working out, from concept and design on paper, to CAD, to a working prototype.
Comments | Trackback | # 
 Saturday, July 26, 2008
TS-2 Mic Preamp - Motherboard
Sunday, July 27, 2008 3:24:01 AM (Central Daylight Time, UTC-05:00) (  |  |  )

Anyways... finally got some time tonight to do some work on the motherboard.

First, populated the PSU section to see if it works... yup, A.O.K.  (had to jumper the switch temporarily since the motherboard isn't hooked to the switchboard.)

So far so good, the switchboard, 48V section, and now the DC-DC section are all working fine.

Work done so far... all resistors, zeners and diodes stuffed.


Tomorrow after church service, I'll solder the caps, IC sockets, pots and switches and XLRs, then start testing.

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TS-2 Mic Preamp - Switchboard Prototype
Sunday, July 27, 2008 3:23:06 AM (Central Daylight Time, UTC-05:00) (  |  |  )
Built the TS-2 switchboard PCB, tested the 48V phantom power section and it works A.O.K!

LEDs will be mounted under the board.

I can already see a few minor changes to the board design... need to push the switches a bit more forward, maybe by 0.1"

The height clearance is perfect... about 1mm for the caps and about 2mm for the switches between these parts and the celing height of the case. Real tight... 

Again, here's the initial design that existed only on the computer.


And here it is, in real life Smiley  (with a few minor changes as you can see.)


Now, off to build the main motherboard.  Grin

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 Wednesday, July 23, 2008
TS-2 Mic Preamp Prototype PCBs
Thursday, July 24, 2008 3:21:03 AM (Central Daylight Time, UTC-05:00) (  |  |  )
UPDATED:

New prototype boards came in today... wohoo!


Let's do some test fittings...

The (2) VU Meters


and oh yeah.... 2 input transformers.


This is the switchboard...


A preview of things to come...


Next step: Build a prototype using these new boards and see if it works.

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 Thursday, June 05, 2008
Audio Testing of new SC-1 Solo prototype.... SUCCESS!!!
Thursday, June 05, 2008 11:11:54 PM (Central Daylight Time, UTC-05:00) ( )



Finally finished wiring the preamp to XLR jacks. Connected to my RP8 active monitor, hooked up a 150-ohm terminated XLR at the inputs to simulate a mic connected, then crank up the gain and volume to max.... and listened....

No hum, no RF buzz... even at 72dB gain setting, and even though it's running and powered by a DC-DC converter PSU and wall wart. Smile

As you can see from the photo, the XLR jacks are right beside the DC-DC converter PSU, and the wires are LAID ON TOP of it!

I am so pleased and happy with this... I can now breathe easily. Oh this is going to be great!!!!

Connected the SC-1 Solo prototype to Channel 1 of my MOTU 828mk2, set the SC-1 Mic Pre gain to 72db max, volume to max, input XLR terminated with 150-ohm (to simulate a mic) and recorded the resulting audio in DP 5.

LISTEN TO THE AUDIO SAMPLE
http://www.fivefishstudios.com/audio/SC1Solo-NoiseTest.mp3

Okay... that noise you're hearing is with the preamp set to 72dB gain.. 72!!!! And volume at max. This is not "hiss" recorded with shorted inputs, or minimum gain...

And to make it even more mind-boggling... all this powered from a WallWart PSU... and a DC-DC converter.

And to visualize what you're hearing...





I am personally amazed. Smile


UPDATE: The spike you see up is most probably 15.734 Khz.... i.e. TV Horizontal Scan Frequency interference. (I do have a 20" TV a few feet away, yeah the old CRT kind of TV).

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 Wednesday, June 04, 2008
DIY DC-DC Converter PSU working!
Wednesday, June 04, 2008 11:08:43 PM (Central Daylight Time, UTC-05:00) ( )


Oh yea!!! working sweet.

A few misadventures while building it... was in too much of a hurry... I inserted a diode backwards in the 48V section, which effectively shorted the thing... the IC chip and board got a little warm... but no damage.

Desoldered it, and put in a new one, (made sure to install it properly) and now the 48V section works perfectly!

Found a little error in my header jumper... my original intention was using a jumper to activate or deactivate the 48V section (in case the user doesn't need it, will also conserve battery power)... but I miswired it so now the 48V section is always available and it's the split psu section that can be disabled or enabled... dumb backwards! I'll fix this on the next PCB revision.

Connected the 12VDC wall wart... measured 27Volts on the 48V section, adjust the onboard trimmer for 48.05 Volts... and now we have a working +/- voltage rails plus 48Volts output.

But yea, everything is working great. See the little LED lit up? It's a sign that the future looks bright.

I just need to continue to populate the board and complete the testing.

UPDATE:



Finally finished building the first SC-1 Solo prototype using the latest PCB design, and latest DC-DC Converter PSU design.

I haven't passed audio through it yet, but I did some power up testing, measuring voltages, etc... everything looks perfect!

I need to get some sleep. Will do audio testing later.



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 Thursday, May 22, 2008
New PCB for SC-1 Solo Mic Pre Kit + DC-DC Converter PSU
Thursday, May 22, 2008 11:04:38 PM (Central Daylight Time, UTC-05:00) ( )
So I'm getting ready to send out the new DC-DC prototype... and with the new PCB size, it will fit the smaller case that I wanted to use in the first place.

I created a combined PCB of the SC-1 and this new DC-DC PSU... The whole PCB is sized so it fits perfectly inside the case, and just needs to slide right in. So we'll see how it goes.



I did a little Photoshop trickery to make it look a little realistic... it's not perfect, but good enough.

I'm trying to minimize wiring work, because this is the most tedious of all jobs. So the only wiring work that needs to be done here is for the input and output xlr and the LED power ON indicator.

Alrighty... ordered some 10pcs of prototype PCBs from the factory. Should be here in a week.

These prototype PCBs alone costs $18.60 each. I hope I didn't make a mistake on these board layouts otherwise, that's wasted money.

We'll build 4 prototypes and if they all work, and no bugs... we're going into production very soon... maybe the final production PCB will be ready by end of June. I still need to figure out what to do with the case (finishing)... maybe use a silkscreen to label the front panel. I'll have to outsource that to a factory.

If this gets launched in June, it will also mark the 1st anniversary of FiveFish Studios. We launched the SC-1 kit about the same time last year.

The SC-1 Solo will not be sold as a kit but as a finished product, complete with case, wall wart, etc.

Yes!... it is RED. and it looks great.

So far, this is the biggest sized PCB I've ever ordered. Hope to populate this board and test it ASAP. I can't wait.


Comments | Trackback | # 
 Wednesday, April 02, 2008
SC-1 Solo Preamp (Prototype) powered by 12VDC wall wart (or battery)
Wednesday, April 02, 2008 7:22:20 PM (Central Standard Time, UTC-06:00) (  |  |  |  )
I'm making CAD measurements of trying to fit an SC-1 preamp plus a Mini-IO module in my extruded aluminum "brick case"... hmmm.. its a tight fit, the TRS jack is almost hitting the top of the case, and the soldered terminals touching the blue trim potentiometer of the SC-1.

I'm concerned about the terminals touching the blue potentiometer. It's plastic so it's non conductive so maybe it's not even an issue. If the case has an extra 0.1" height, it would have been fine. But given this TRS jack is the hi-Z input, I'm afraid it might have side effects.

For sure a VU-meter will fit inside without problems.

Unless I can find a slightly taller case, the SC-1 Solo will probably consist of the SC-1 and a VU meter, plus the PSU board. (at least, for this 1st prototype I'm making.)

My eventual goal is to find a case that will be tall enough to fit an SC-1 plus the IO-module (with input/output transformers)/Mini-IO, and maybe even the VU meter. Now, that would be some hot SC-1 Solo product!

Okay...did the CAD drawings, created the CNC programming then tested it on some .125" scrap aluminum. Looks good.

Loaded the "real" panel and let the program run... X fingers!

Yes... everything fits like a glove! No more manual drilling with a drill press or filing around to make everything fit.

Of course, it takes hours of prep work on the CAD/CAM, testing and final setup... and only about 3 minutes of actual CNC time on the router. Shocked

Some photos:





Did the rear panel CAD/CAM/CNC today... I goofed up making measurements on where the DCJack holes should be... so had to do some fudging with a manual file. It's okay... this is just a prototype. But I fixed the CAD drawings to reflect the proper dimensions.

Some photos:

The DC-DC Power Supply installed on the rear panel.


XLR jacks installed


I do have one concern here and that is... with the XLR jacks so near to the DC-DC PSU, will it affect the preamp's performance? From my limited bench testing, it doesn't seem to be... but the proof is in the pudding... so we'll see how this prototype performs.

I have seen one preamp though (and I'm not naming names) and they have a DC-DC PSU, and a microprocessor, and it's associated crystal clock, and 2 preamps crammed into one small case.

By comparsion, what I have is "roomy" compared to what's inside this other preamp.

And finally... a preview of things to come. Rear View of the SC-1 Solo case.


Arghhh... those XLR bolts are too shiny! Will have to replace them in the final prototype with stainless steel bolts to cut down the bling factor.

I'm also using a flat head stainless steel screws to attach the plate to the main case... but I can't properly chamfer the hole openings because the plate is only .036". If it was thicker, I can get away with it. So the (4) corner screws will have to be replaced with pan head screws (also stainless steel)

All these "minor" fixes will be done as the very last step.

SC-1 Solo Preamp

Features:
- Low-Noise, transformerless, High-Quality Mic Preamp
- All solid-state design, using chipsets from THAT Corp and Burr-Brown
- Soft-start, slow ramp-on +48V phantom power
- Crystal clear Red LED indicator for phantom power
- Electronically balanced input and output stages
- 12-position Grayhill gain selector switch
- Gain range from +6 to +72dB, in 6dB increments
- Input RFI protection
- Input clamping protection
- Output surge protection circuit
- Output RFI protection
- Powered by a linear, regulated 18-0-18 Volts supply, with +48VDC for clean power delivery
- Reduced clicking and popping when changing gains
- High quality Bourns, sealed, conductive plastic potentiometer for volume control
- High quality C&K PCB Mounted switch
- Gold-plated, machined, low-profile IC sockets
- Use of high quality 1% Metal Film resistors, and high-quality ceramic and electrolytic capacitors
- With 5-LED VU Meter
- Neutrik XLR input and output jacks
- Powered by 12VDC wall wart 



Comments | Trackback | # 
 Wednesday, March 26, 2008
DC to DC Switching PSU (12Volts to +/- 18V & 48V)
Wednesday, March 26, 2008 6:31:57 AM (Central Standard Time, UTC-06:00) (  |  |  )
It's done :)  My switching DC-to-DC PSU.

I've been working on this design on and off since October 2007. Several prototypes later, and many $$$, I'm happy with it.  All output voltages are regulated and adjustable via multiturn trimmers, +18, -18 and it's a true +48V phantom power... all derived from a single 12Volt input.  Outputs are short circuit protected. Just a big spark, but keeps on ticking. Nothing gets blown. 


http://farm3.static.flickr.com/2322/2365867488_5f14133bbd.jpg

Powering my preamp and my I/O module (input and output trafo, pad, polarity) with Active DI, via 12V wall wart. No hashing sound, no RF leak, no noise. (Well, okay... when you're at 66-72dB gain... but could be caused by everything not in a metal enclosure.)


http://farm4.static.flickr.com/3068/2352224005_5dc492842c.jpg


Output on all 3 rails are typical like below:

http://farm3.static.flickr.com/2376/2365001131_8b2c1a26ac.jpg

Switching spikes on the DC output of about 0.06Vpeak-to-peak, and interval of 33.333Khz. I can set switching freq. to about 60Khz but the spikes get larger.

So I compromised for smaller spikes at a lower switching frequency... i.e. smaller spike/transients, less RFI energy emitted, less chance that it will interfere with sensitive mic pre circuitry.

Comments | Trackback | # 
 Thursday, March 20, 2008
Mic Preamp SC-1 with Cinemag input/output transformers
Thursday, March 20, 2008 3:54:00 PM (Central Standard Time, UTC-06:00) ( )
Yes!... got some time to do some electronics work today... away from the purchasing role.

Finally built and tested the final, final, FINAL prototype of the IO-module. And it's great.

Man, I love the sound of the Active DI going through the input transformer. Actually, love the sound of anything going through it.

Some pics:



Now, I haven't sent the PCB out for mass production yet, but I have (4) prototype PCBs left. I'm keeping (2) so that leaves (2) extra ones...

I know somebody out there is waiting for this patiently... you're getting these PCBs way in advance of the others.

I'd need to drill some square cutouts first on it... like this


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 Tuesday, February 26, 2008
ATI X800XT Fan Upgrade for Mac G5
Wednesday, February 27, 2008 5:47:28 AM (Central Standard Time, UTC-06:00) ( )
So I bought this AT X800XT card... back when it was $499... the first one after a few short months, the fan got noisy and was dying... I sent it back to ATI, then ATI sent back a faulty unit (blocks appearing on the screen), so I had to resend it back again and then I'm good again for a few months.

This morning, my 2nd monitor (A Samsung) wouldn't come up. Just black. At first I thought my monitor died... bummer. That got me thinking... maybe I should get another 23" Cinema LCD :) The prices have fallen down to $799. (I got mine back at $1999).

Then just to be sure it's the monitor, I swapped things around... and lo and behold, my Samsung monitor was working!

I opened the G5 case, and see that the video card fan was totally dead... not spinning. NOT GOOD. I don't know how many days I've been running with this fan not spinning.

So today I pulled out the X800XT card and put back in my stock video card (fanless) just so I can continue working. It's a good thing to have spares.

I'm not going to bother sending this back to ATI again. I bought some replacement aftermarket fan and will try to fix this thing instead. Remove the junk ATI fan and use another one instead.

Will update this post as I go....

I just hope the 2nd video port isn't permanently damaged.

I just noticed today that due to the failed fan on my video card, it almost fried the components at the bottom of the PCB. Yes, it smell burnt. I was kinda disappointed when I saw this. I'm thinking maybe my video card is fried (literally).





 Remove the old crappy fan from my ATI card. This fan sucks. Do you hear that ATI?????




You can see the old thermal paste sticking on the cpu. So we'll need to clean that out.




And here's the clean chip. I just used an old cotton shirt, and an old toothbrush. Wiped it clean and made it shiny.

I'm using a Zalman VF700-Cu Quiet VGA Cooler fan. It's pretty cheap. $20 I think.

It also comes with some blue small heatsinks for the other chips (RAM?) on the card.

The connector of the Zalman fan isn't compatible with the headers on the video card.

So what do you have to do? Get a cutter, cut the wires on the new fan, cut the wires on the old fan and solder them together a'la Frankenstein. :)

I used some heatshrink tubing to insulate the connection. You can see it in the photo below, along with the new blue heatsinks.



Then... the moment of truth... Put it in my G5 and see if it still works. (Remember, the parts at the bottom of the PCB smells burnt and looks a little crispy.

And the result....... IT STILL WORKS! Now my second monitor works, and not shutting down (turning black). I've got good video on both monitors! :)

So that's done... total time, maybe 30 minutes.

Comments | Trackback | # 
 Saturday, February 02, 2008
DC to DC Switching PSU (12Volts to +/- 18V & 48V)
Saturday, February 02, 2008 10:12:25 PM (Central Standard Time, UTC-06:00) ( )


Well, this DCC psu is giving me the headaches. One day, I thought I licked out the problem and it's as quiet as can be... next day, I turn it on, and the fyring noise is back again coming out of the speakers.

I've tested and used my oscilloscope to look for possible problems in the DC-to-DC converter, (though I did found some oscillations that I eventually fixed), there doesn't seem to be any improvement in the crackling sound coming out of my test preamp.

This PSU ripple has never been better, the "frying bacon" sound coming from the inductors is almost negligible, the waveform looks good... but still! There's that crackling sound coming out of the preamp.

In situations like this (i.e. when I become desperate)... I do weird things to my projects. I mean, what more can I lose?

And this time, I decided to remove jumper J1 on the SC-1 preamp, and run using AC coupling. That's strange... the crackling sound STOPPED!

So I went to my shelf, grab a new OPA134 chip, swapped out the old IC2 chip on the pre with the new one, and VOILA! The stupid crackling noise STOPPED! IT's as clean as can be... running on the DC-DC PSU.

I'm going to leave the DC-DC PSU running the whole day, and the preamp... and see if the noise comes back. Otherwise, I think a marginally defective IC2 on the SC-1 PCB was the cause of the noise problem, and not my DC-DC PSU.

I'm happy to report though that using an AC Adapter with my DC-DC PSU powering the preamp and the Mini-IO module, the AC Adapter doesn't even get WARM!


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 Sunday, January 20, 2008
IO-Module Prototype #002 Testing
Monday, January 21, 2008 1:01:53 AM (Central Standard Time, UTC-06:00) (  |  )
Okay, so I got the latest prototype PCB for the IO-Module... time to build prototype #002.

I usually build 2 to 5 prototypes before the kit goes on sale. I want to make sure that it works, that everything works right and performs great, easy to assemble, the parts list correct and all that. It's the DETAILS that matter!

Some pics...

Since the PCBs are prototype, there are no cutouts for the transformers. On the final production PCB, the holes will be cutout by the factory.



So we drill some 3/8" holes on each corner of the square cutout.




And here's a pic of the drilled PCB.



Using a jig saw, we do a rough cut of the square hole... then use a file to smoothen the edges.



Next, we test fit our transformer (Cinemag CMOQ-2S) into the PCB... fits perfectly on the 1st try!



Here's the bottom view.



And a photo showing both the input and output transformers.

Comments | Trackback | # 
 Friday, January 11, 2008
Mini-IO PCBs are here!!!!
Saturday, January 12, 2008 5:31:36 AM (Central Standard Time, UTC-06:00) ( )
This MINI-IO is very fun and easy to assemble. Within a few minutes, you could have a completely assembled kit.

To re-iterate... this kit gives you POLARITY CONTROL, -20dB PAD, and MIC/INST select switch, plus an onboard ACTIVE DI with fully, electronically balanced outputs.

It is a stripped-down version of the IO-MODULE. The only difference being the IO-MODULE has provisions for input and output transformers.

The MINI-IO is meant to be used in conjunction with a preamp module. It works with the SC-1 preamp kit, or any preamp you're working on where you wish to add the above controls and features.

Power Supply Requirements are +18/-18, +48V for phantom power.






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 Wednesday, January 02, 2008
CNC Machine
Wednesday, January 02, 2008 10:22:35 PM (Central Standard Time, UTC-06:00) ( )
I finished assembling my CNC. (Got it from eBay)... Using Mach3 software... It's a complicated piece of software but I think I'm getting the hang of it. I'll probably buy it after I play with it some more.

Tested the CNC doing some movements and "pretending" to cut/route something... I need to buy a router to install to it so it can do some real cutting.

Some photos:







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 Friday, December 28, 2007
SC-1 Preamp + IO-Module
Friday, December 28, 2007 10:21:06 PM (Central Standard Time, UTC-06:00) ( )
Took some photos today.



Did some more tweaking on the IO-module PCB design... getting ready to pull the trigger for another prototype PCB run.

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 Sunday, December 23, 2007
Oscilloscope photos and audio samples ... DCC-1848
Sunday, December 23, 2007 10:19:52 PM (Central Standard Time, UTC-06:00) ( )
Using the DCC-1848 prototype PSU, loaded with my SC-1 preamp, the IO-module and the VU meter board.

0.2V/DIV


0.1V/DIV... you can see some noise/spikes occuring at regular intervals.


Not bad...

And audio samples.
The Setup:
My SC-1 preamp... with an IO-module and VU Meter board. Everything powered by my proto DC-DC Switching PSU... (12Volts input to +/-18, +48V). Preamp outputs going to a patchbay, then going to a MOTU 828mk2 input. Recorded using Digital Performer. MP3 set at 256Kbit sample rate. Preamp, IO-module, VU meter board and PSU unracked, no case, no shielding, no grounding... just PCBs sitting on my workbench.

First sample:... preamp gain set to 54dB, *unterminated XLR inputs*, max volume
http://www.fivefishstudios.com/audio/DCDC54dB0R.mp3

Second sample... preamp same 54dB gain as above, but XLR inputs terminated with 150R resistor.
http://www.fivefishstudios.com/audio/DCDC54dB150R.mp3

Third sample.... preamp gain set to 72dB, *unterminated XLR inputs*, max volume
http://www.fivefishstudios.com/audio/DCDC72dB0R.mp3

Last sample... preamp gain at 72dB, 150R terminated XLR inputs, max volume
http://www.fivefishstudios.com/audio/DCDC72dB150R.mp3

OK! I think I found the problem and managed to reduce the spikes in the DC INVERTING section. I don't know if the pictures make it obvious but it's a definite improvement.

EARLIER


FIXED? Definitely better... reduced noise and pikes.


I think I'm ready to do a revision 2 of the DC-DC Converter PCB, so I don't have components hanging on the top and bottom of the board (was trying out different things). I think the rest of the problem is now caused by the PCB layout.



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