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Total Posts: 88
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Comments: 9

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, October 02, 2008

TS-2 Mic Preamp Production

Thursday, October 02, 2008 7:33:49 PM (Central Daylight Time, UTC-05:00) ( DIY | Project Kits | Recording | TS-2 Preamp )

So I'm starting "production" of the TS-2 Mic Preamp units. Everything will be handbuilt here in "the FiveFish Studios Lab."

Initial run will be 8 units. Sell the 1st (8) and then use the money to fund the next batch of units.

These are (2) channel mic preamps, with DC servo, and internal buffering. Using THAT chips, Burr Brown chips. Output using balanced line driver from THAT. Includes (2) channel VU meter. Polarity switches on both channels, individual 48V phantom power switches, and an ON/OFF switch for the VU meters (to be discrete during taping :). XLR Ins and outputs. Powered by 12VDC from AC wall adapter or portable DVD batteries.

Intro Price: $499

Everything is in a pipeline... panels will need to be manufactured, milled. Cases bought, and everything put together and tested in the coming weeks. Hopefully, I'll have finished units ready before Thanksgiving.

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Friday, September 05, 2008

TS-2 Mic Preamp Testing

Friday, September 05, 2008 7:12:23 PM (Central Daylight Time, UTC-05:00) ( DIY | TS-2 Preamp )

New Preamp Testing

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Monday, August 25, 2008

TS-2 Mic Preamp Battery Powered

Monday, August 25, 2008 5:05:55 PM (Central Daylight Time, UTC-05:00) ( DIY | SC-1 Preamp Kit | TS-2 Preamp )

Start doing prototype of the case... get dimensions of holes and stuff... drill manually, make corrections, keep notes... do some filing to fix the screwups.

Some notes:

The Motherboard, Switchboard and VU meter PCBs... crammed in a 2-inch high, 6" width case. As you can see, it is tight... the switches and capacitors have literally millimeter clearances from hitting the ceiling. The distance between the motherboard and switchboard perfectly aligns with the PCB slot of the case.

Attach the front panel to the PCBs. Check out the input transformer peeking from the side.

Photo of the blue anodized case with the black anodized rack handles temporarily attached.

The switch toggle handles peek out just enough... No accidental flipping of switches. It takes some effort to consciously flip it. Using your thumb and fingernails seems to be the easiest way to toggle it.

The blue anodized finish of the case gives it a weird effect when photographed... kinda like a soft glow coming from the surface of the case.

Forgive the crooked holes for the VU meters, and too large holes for the switches. Smile

These were manually drilled.

I'm going to finalize the dimensions, and have a prototype shop do a sample panel for me using CNC.

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Tuesday, August 19, 2008

TS-2 Mic Preamp Prototype

Tuesday, August 19, 2008 5:57:23 AM (Central Daylight Time, UTC-05:00) ( DIY | PCB | TS-2 Preamp )

So hooked up my battery and 2 condenser mics to the pre... turn on power, turn on phantom for both channels, and recorded the VU meter "in action"...

Note: The audio in the video was recorded by the camera.

Youtube video here. (Make sure to watch in high quality mode and view the annotations.)

Enjoy!

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Thursday, July 31, 2008

More TS-2 Battery Testing

Thursday, July 31, 2008 5:59:37 AM (Central Daylight Time, UTC-05:00) ( DIY | TS-2 Preamp )

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

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Monday, July 28, 2008

TS-2 Prototype Working!!!

Monday, July 28, 2008 5:58:31 AM (Central Daylight Time, UTC-05:00) ( DIY | PCB | TS-2 Preamp )

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

Woohoooo!!!!! YES! 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) ( DIY | PCB | TS-2 Preamp )

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

Woohoooo!!!!! YES! Grin

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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Saturday, July 26, 2008

TS-2 Mic Preamp - Motherboard

Sunday, July 27, 2008 3:24:01 AM (Central Daylight Time, UTC-05:00) ( DIY | PCB | TS-2 Preamp )

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) ( DIY | PCB | TS-2 Preamp )

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.