BA500 Mic Pre Amp BUILD THREAD 500/51X

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BA500 Mic Pre Amp BUILD THREAD 500/51X

Postby Joe Malone » Mon Oct 24, 2011 10:46 am

BA500 Mic Pre Amp BUILD THREAD 500/51X

The BA500 is a 500/51x version of our well know Baby Animal mic pre.
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BA500 Parts List here

Complete BA500 kit with every part down to the last nut and bolt.

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BA500 PCB kit
1. BA500 main pcb is a stripped down INX5 pcb so its overlay has the exact parts and values marked on it for the BA500 kit to make the build easy.
2. 51X and 500 compatible with 51X pins cut off. Kit fits all 500 and 51X racks and lunchboxes.
3. PCB automatically uses highest power available. +/-16v for 500 and +/-24v for 51X.
4. BA500 PCB also has mix buss out on pin 11 for Radial Workhorse racks.

BA500 Schematic here

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BA500 PCB. For 500 series racks cut and file 51X pins off)
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Fit the two BAT85 diodes bending the legs sightly outwards to hold them in place.
Diodes are POLARIZED and must go in with there stripe matching the strip on the PCB overlay.
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Solder the two BAT85 diodes bending the legs sightly outwards to hold them in place.
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Cut BAT85 diode legs off at top of the solder joint and double check no solder joints missed soldering.
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If you are not 100% with resistor colour codes use a multimeter to check values as you place the resistors
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Fit all resistors at once bending the legs sightly outwards to hold them in place. This helps to make sure no resistors are put in the wrong position.
Note 1. Replacing R19 51R with new 33R give slightly better low frequencies response when using JLM111DC and JLM111DC compact output transformer.
In future kits we will be replacing all 51R with 33R. So R19 and R20 will both be changed to 33R on new PCBs.

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Solder all resistors while holding PCB firmly upside down on flat surface.
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Cut all resistor legs off at top of the solder joint and double check no solder joints missed soldering.
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Fit the 4 x 1N4007 diodes. Diodes are POLARIZED and must go in with there stripe matching the strip on the PCB overlay.
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Solder 1N4007 diodes in once you have checked there POLARITY is correct.
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Fit 3 x 47pF ceramic caps in place. The 47pF caps are NOT Polarized so can go in either way around.
Fold 47pF caps down flat to PCB before soldering them.
Note there is also a ceramic 220pF cap marked 221 that is for CL2 (Cload2) in the BA500 kit. Do NOT FIT CL2.
We have found NO CL2 is needed in the current configuration as long as Cload on the GO Between 500 is fitted.

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Fit 6 x 1mm sockets for 99v opamp. Do NOT press the sockets in. Just let them sit in the holes. Use a piece of cardboard or the stainless steel bracket to hold them in while turning the PCB over.
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Solder 6 x 1mm sockets in place
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Fit and solder DIP8 socket in other opamp position. Make sure the POLARIZED socket matches the PCB overlay.
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Fit and solder 2 x 0.1uF MONO caps in place. The 100nF caps are NOT Polarized so can go in either way around.
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Fit and solder jumper pins in place
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Fit and solder IDC headers in the POLARITY shown. Do not reverse. Triangle on header indicates pin 1 which is the square pad on the PCB.
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The front opening in the IDC headers should both now be facing as shown below.
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Fit and solder 4 x 100uF Electro caps to PCB. The 4 x 100uF caps are POLARIZED so must have there long positive leg fitted to + marked on PCB overlay.
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Fit and solder trim pot. The trim pot is POLARIZED so must go in as shown on PCB overlay. Adjustment screw should be as shown on overlay.
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Fit and solder 4 x 470uF Electro caps to PCB. The 4 x 470uF caps are NON POLARIZED so can go in either way around.
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Fit OPA2604AP opamp in the correct POLARITY shown. 99v opamp can be fitted now or later. BA500 PCB is ready to go.
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Put nuts and bolts etc back into zip lock bag the BA500 PCB kit came in to make sure they are not lost while you build the Small Go Between 500 PCB next.

Go Between 500 kit

BA500 Schematic here

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Go Between 500 PCB
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If you are not 100% with resistor colour codes use a multimeter to check values as you place the resistors
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Fit all resistors at once bending the legs sightly outwards to hold them in place. This helps to make sure no resistors are put in the wrong position.
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RPad is 120R for 20dB Pad (If you want unity gain with pad in and and gain at minimum make RPad 68R for 26dB Pad)
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RLoad is 10k for OEP/VTX input transformer & JLM14 wired a 1:8 (Rload is 2k2 for JLM14 input transformer wired normally as 1:4)
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Solder all resistors while holding PCB firmly upside down on flat surface.
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Cut all resistor legs off at top of the solder joint and double check no solder joints missed soldering.
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Fit Cload 220pF ceramic caps in place. The 220pF cap is NOT Polarized so can go in either way around.
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Fit & Fold cap as shown and solder 10uF Electro caps to PCB. The 10uF cap is POLARIZED so must have there long positive leg fitted to + marked on PCB overlay.
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Fit and solder IDC headers in the POLARITY shown. Do not reverse. Triangle on header indicates pin 1 which is the square pad on the PCB. Trim back plastic ribs on header with its back against OEP/VTX transformer.
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Fit OEP/VTX input transformer with 1mm gap from PCB and solder in place. It can only fit to the PCB one way around.
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The three switches for the Go Between 500 need have to have there 6 legs straightened with a set of small long nose pliers like below.
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Fit switches as shown below so the PCB is at 90 degrees to the toggle.
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Line the three switches up and solder one terminal on each switch as shown below.
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PCB's are now ready for final assembly
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Fit the 4 x 12mm countersunk screws found in the LA500 PCB kit to the bracket and screw 6mm nylon spacers to them.
Nylon spacers have countersink on one side that should go down on to the bracket to take the protruding part of screws countersink.
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Last chance to cut off 51X pins if converting the PCB to a 500 version.
Fit BA500 PCB and hold down with shakeproof washers and nuts provided in the BA500 PCB kit.
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Remove locate tags on both pots with sidecutters as shown below.
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Fold legs 90 degrees with long nose pliers to make soldering easier later.
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Strip 5mm of insulation of the 4 wire colours provided and twist wire strands together and tin with solder.
Place colours as shown for meter in GO between 500 PCB and solder in place.
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Solder into GO Between 500 PCB and cut excess off.
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Fit meter into bracket and hold in place with one or 2 bolts hand tight. Twist 4 wires and cut to length.
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Strip 5mm of insulation of the 4 wires and twist wire strands together and tin with solder.
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Wind the back nut fully down on to the 3 switches. Fit the flat washers on next.
Cut the sides of the middle flat washers with sidecutters so it does not overlap the other washers.
Fit the 3 shake proof washers on next. Fit to bracket and put on second nut and tighten.
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Solder all toggle terminals and cut excess off.
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Solder wires to gain pot as shown.
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Solder wires to Z pot as shown for OEP/VTX 100k pot. (Link unused front pot tags to back pot tags to make 50k pot for JLM14)
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Fit front panel and hold in place with nut on gain pot.
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Fit the 4 meter screws in GENTLY and do NOT over-tighten them or you may strip the bracket thread. Lock-tight can be useful in a always traveling lunchbox to stop them shacking loose.
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Solder colours as shown on the meter terminals.
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Trim gain pot wires and strip and tin them and solder to Go Between 500 pCB as shown below.
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Trim Z pot wires and strip and tin them and solder to Go Between 500 PCB as shown below.
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Fit 48v LED into GO between PCB and then push into front panel hole and solder and trim.
long LED leg shoudl go into the square solder PAD with the A beside it.
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If you have ordered the FET DI kit fit to front panel as shown below. If no DI fit the 11mm blanking plug.
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JLM111DC with wiring and hardware pack. Be warned do NOT touch the 3 yellow and black wires while handling the transformer as these are very thin wires and can easily be broken
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Fit ribbon cable between JLM111DC transformer and JLM111DC header on LA500 PCB.
Use shallow ribbon cable end with no cable relief clip fitted at the transformer end.
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Fit ribbon cables provided to join the GO Between PCB headers to the BA500 headers as shown below.
Double check you have all headers on PCB correct way around and check red wire in ribbon cable lines up to triangle on header that marks pin 1 square solder pad.
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Fit opamps to there socket as shown below. Note TL072 opamp pin 1 circle is closest the 99v.
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Fit GND jumper as shown below
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Ready to test
Adjust blue 25 turn trim pot with small screw driver to get the VU meter 0VU point to line up to the reference level you want with a 1khz tone. Usually this would be +4dBM or 12 to 14dB down from 0dFS of your A/D.com/BA500/102%20Gain%20pot%20wiringJPG[/img]

Fit 48v LED into GO between PCB and then push into front panel hole and solder and trim.
long LED leg shoudl go into the square solder PAD with the A beside it.
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Joe :-)
JLM Audio
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chadblinman
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Re: BA500 Mic Pre Amp BUILD THREAD 500/51X

Postby chadblinman » Sat Apr 28, 2012 4:38 pm

Outstanding work! Thanks for all the care you put into these build threads.

Would it be feasible to add a switchable HP filter to this? (Of course I'm thinking of the version without the DI input.) A fixed 80Hz filter would be great. Dual freqs, say 80 and 160Hz, would be even better...

What are your thoughts, Joe?

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Re: BA500 Mic Pre Amp BUILD THREAD 500/51X

Postby Joe Malone » Mon Apr 30, 2012 11:57 am

chadblinman wrote:Outstanding work! Thanks for all the care you put into these build threads.

Would it be feasible to add a switchable HP filter to this? (Of course I'm thinking of the version without the DI input.) A fixed 80Hz filter would be great. Dual freqs, say 80 and 160Hz, would be even better...

What are your thoughts, Joe?


Adding a HPF is easy when NO DI is fitted. The 2 wire jumpers that would normally link over the 3rd IDC header when no DI is fitted so the audio path is complete would just need one jumper changed instead to a capacitor for HPF with a switch across it to short it out for FLAT. The only thing is the HPF frequency will change with the Z impedance control.

So adding a capacitor with shorting switch into one of the 2 wire jumper positions.
SHORT = FLAT
80Hz = 3uF @ Z centre, 220Hz @ Z min, 20Hz @ Z max
160Hz = 1.5uF @ Z centre, 440Hz @ Z min, 40Hz @ Z max

This cold be done with a rotary or toggle switched mounted in the DI hole and 2 x 1.5uF 50v caps very easily.

Let me know if you need any photo's or drawings to show the detail better.
Joe :-)

JLM Audio

Capturing Audio without Injury

chadblinman
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Re: BA500 Mic Pre Amp BUILD THREAD 500/51X

Postby chadblinman » Tue May 01, 2012 6:00 am

Joe Malone wrote:The only thing is the HPF frequency will change with the Z impedance control.

So adding a capacitor with shorting switch into one of the 2 wire jumper positions.
SHORT = FLAT
80Hz = 3uF @ Z centre, 220Hz @ Z min, 20Hz @ Z max
160Hz = 1.5uF @ Z centre, 440Hz @ Z min, 40Hz @ Z max

This cold be done with a rotary or toggle switched mounted in the DI hole and 2 x 1.5uF 50v caps very easily.

Let me know if you need any photo's or drawings to show the detail better.


Hmm, interesting! That does sound quite easy to do, although the interaction with the Z control is questionable. Is there any way around that?

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HPF options for BA500

Postby Joe Malone » Thu Aug 02, 2012 10:05 pm

Two way of adding HPF to BA500 Mic pre

1st way to have HPF frequencies that do NOT move when Z control is moved is to cut the red wire in the short IDC ribbon that connects the BA500 to the JLMIO port on the BA500
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Insert 1uF cap in series with shorting switch and parallel cap or caps. 2nF cap = 80Hz and 1nF = 160Hz etc (All caps 50v or higher MKT block types)
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2nd way to have HPF frequencies that will move when Z control is moved is to open one of the links in the dummy IDC header which is fitted when no DI is fitted. Remove glue and open one of the links
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Insert shorting switch and parallel cap or caps. These caps will be much larger in value than 1st way (I will add some values next week here) (All caps 50v or higher MKT block types)
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Joe :-)

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chadblinman
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Re: BA500 Mic Pre Amp BUILD THREAD 500/51X

Postby chadblinman » Fri Aug 03, 2012 3:22 am

Thanks, Joe!

One more novice question: Can you further specify the caps for both methods? (Type and voltage)

c.

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Re: BA500 Mic Pre Amp BUILD THREAD 500/51X

Postby Joe Malone » Fri Aug 03, 2012 8:03 am

chadblinman wrote:Thanks, Joe!

One more novice question: Can you further specify the caps for both methods? (Type and voltage)

c.


Edited HPF post to show standard MKT type block caps 50v or higher will be the best to use.
Joe :-)

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BA 500 - HELP!!!...not passing signal...

Postby grimmstar » Fri Jan 11, 2013 1:14 pm

Hi all,

Just finished my first build. Loved every second of it. Anyway, a bit of a problem I need to troubleshoot, and being a total noob, definitely need help doing it.
To be as detailed as possible without writing a novel, It powered up in the 500 rack, VU light worked, 48v LED worked and functioned properly with the switch, nothing exploded, so I was very excited. However, when I quickly went to try a mic to continue with the test, it didn't pick it up. Tried another module in the rack, worked fine. Tried the BA 500 again, no sound.
In the build thread, it only shows the OEP input tranny install, not the JLM 1:4. I tried to find a detailed description of the proper install for it, but only saw a couple pictures, and a thread that had said the black wire doesn't go to anything. I soldered the colored wires to their labeled pads and screwed it into the PCB.
Does the black wire need to be connected to something? If so, would that be the culprit?
I don't think I put any resistors in the wrong spot, being careful to check them via a multimeter, but being a noob as stated, I don't know if that would cause this or not.
Any help, guidance, advice, obviously appreciated. Thanks so much. Can't wait to get these going...

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Re: BA 500 - HELP!!!...not passing signal...

Postby Joe Malone » Fri Jan 11, 2013 5:01 pm

grimmstar wrote:Hi all,

Just finished my first build. Loved every second of it. Anyway, a bit of a problem I need to troubleshoot, and being a total noob, definitely need help doing it.
To be as detailed as possible without writing a novel, It powered up in the 500 rack, VU light worked, 48v LED worked and functioned properly with the switch, nothing exploded, so I was very excited. However, when I quickly went to try a mic to continue with the test, it didn't pick it up. Tried another module in the rack, worked fine. Tried the BA 500 again, no sound.
In the build thread, it only shows the OEP input tranny install, not the JLM 1:4. I tried to find a detailed description of the proper install for it, but only saw a couple pictures, and a thread that had said the black wire doesn't go to anything. I soldered the colored wires to their labeled pads and screwed it into the PCB.

JLM14 just needs the four colours soldered to the PCB as marked. And mounted with the mount kit so the white bushes are between the bottom of the JLM14 and the PCB so there is a gap.
RLoad should be 2k2 and Z pot should be 50k (front Z pot legs soldered to the back pot legs so the two 100k pots are in parallel to make 50k pot.

Does the black wire need to be connected to something? If so, would that be the culprit?


Black wire is cut short and folded back into the heatshrink it comes out off. Or insulate with a piece of tape of heatshink tube. Not connected to anything.

I don't think I put any resistors in the wrong spot, being careful to check them via a multimeter, but being a noob as stated, I don't know if that would cause this or not.
Any help, guidance, advice, obviously appreciated. Thanks so much. Can't wait to get these going...

Do you have a DI kit fitted and plugged in ?
If not have you fitted the dummy IDC10 plug onto the 3rd header on the ribbon cable ?
If you do not have either a DI kit or dummy header fitted there will be a hole in the balanced in wiring so nothing will get to the input transformer.

The dummy IDC header which is fitted when no DI is fitted.
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Joe :-)

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grimmstar
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Re: BA500 Mic Pre Amp BUILD THREAD 500/51X

Postby grimmstar » Sat Jan 12, 2013 12:15 am

Hi Joe,

Thanks so much for the reply. I DON'T have the dummy header fitted! So right there could be the issue. I guess there were a few things not in the build thread since it covers the build WITH the DI kit - which I didn't get.
So where would the dummy headers be? Was that in with my parts? I could swear I have no other header(s) left, as I got 2 kits. Both builds have this same exact issue.
With the ribbon cable, the SECOND connector that would normally go to the DI kit, THAT get's connected to top header above or next to the top of the JLM 14 tranny, then the dummy header attaches to the last connector which normally would be in that top spot if the DI was connected?
Or just attach the dummy header to the second connector that's hanging unattached right now, which would normally attach to the DI, and leave the last connector plugged into the header like it is now, completing the path of the "3" cable?
I'll look for the dummy headers as soon as I get to my workshop. If I don't have them, where would I get them, or would I have to order them from you?
Thanks so much, as this seems to be the issue since I don't have the dummy headers attached!
I'll post back if I find them and I'll attach them as per your instructions. If not I'll need to order 2 of them from you.
I'm a complete addict. I was somewhat disappointed the build was over, forgetting I have 2 sweet new JLM pres to rock.can't wait to use them, and they make a great addition to my BA4!!! Can't wait to get more BA 500kits in the near future, and 2 LA 500s. You RULE!!!

grimmstar
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Re: BA500 Mic Pre Amp BUILD THREAD 500/51X

Postby grimmstar » Sat Jan 12, 2013 2:30 am

Hi Joe,

After checking my leftover parts, there wasn't any dummy headers included. So i need 2 of them. Can I pick them up at Radio Shack or a similar store, or do I need to order them from you? If I can buy them here, do I need to apply that thermal paste or hot glue like the header in that picture?
Let me know when you can, and thanks again!
So close... =0)

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Re: BA500 Mic Pre Amp BUILD THREAD 500/51X

Postby Joe Malone » Sat Jan 12, 2013 8:45 am

grimmstar wrote:Hi Joe,

After checking my leftover parts, there wasn't any dummy headers included. So i need 2 of them. Can I pick them up at Radio Shack or a similar store, or do I need to order them from you? If I can buy them here, do I need to apply that thermal paste or hot glue like the header in that picture?
Let me know when you can, and thanks again!
So close... =0)


No need to buy anything just solder join the 2 pairs of terminals together under the Go between 500 PCB as shown in red below.
The 3rd plug on the ribbon cable can be left empty then. And your audio path will be complete.
Image
Joe :-)

JLM Audio

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grimmstar
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Re: BA500 Mic Pre Amp BUILD THREAD 500/51X

Postby grimmstar » Sat Jan 12, 2013 11:43 am

Hi Joe,

Thanks for another fast reply. I actually grabbed a handful of 10 pin headers from a friend of mine who does this, and it would probably be alot easier for my skills, to make 2 dummy headers, than to take apart most of the assembly to get to the board to solder.
To make the dummy header, do I just hot glue the bottom of the header, or clip those pins on the bottom, then cover with hot glue? I noticed in the picture it looks like 2 pairs of pins are soldered together on the dummy header with the glue removed. I'll wait for your info on that.
Once again, thanks so much for the help, once I get the headers on, I'll retest and report. =0)

grimmstar
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Re: BA500 Mic Pre Amp BUILD THREAD 500/51X

Postby grimmstar » Sat Jan 12, 2013 12:06 pm

I'll try one each way for the experience, solder it like you showed, then make a dummy header for the other. I'll take the knobs and faceplate off, unscrew the switches, and turn the Go Between over and solder it.
I'll report back after I solder the first one, then I'll make a dummy header after I hear back from you on how to whip one up. Thanks Joe!
I get to work on it again! =0)

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Re: BA500 Mic Pre Amp BUILD THREAD 500/51X

Postby Joe Malone » Sun Jan 13, 2013 7:59 pm

grimmstar wrote:Hi Joe,

Thanks for another fast reply. I actually grabbed a handful of 10 pin headers from a friend of mine who does this, and it would probably be alot easier for my skills, to make 2 dummy headers, than to take apart most of the assembly to get to the board to solder.
To make the dummy header, do I just hot glue the bottom of the header, or clip those pins on the bottom, then cover with hot glue? I noticed in the picture it looks like 2 pairs of pins are soldered together on the dummy header with the glue removed. I'll wait for your info on that.
Once again, thanks so much for the help, once I get the headers on, I'll retest and report. =0)


The dummy header is the same thing as soldering the 2 sets of terminals together under the go between 500 PCB. it is just easier to remove the dummy connector when adding a FET DI kit later.
See photo's below. Solder the 2 sets of terminals together as shown in the photo below and cut of spare pins and extra length. The glue is just to stop the connections from shorting to anything.
Image
Image
Joe :-)

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