Whistle Rock Audio ML12 preamp BUILD/HELP thread!

[punk]

Hi Mike,

just wanted to say thanks for the kits, the pcb's and the documentation are excellent !!

byron

 

[dissonantdissident]

Hey there,

I'm getting ready to put in my order with mouser, and I noticed that the frontpanel designer file has rectangular slots, for the pushbuttons, but the BOM has the circular ones.  Anybody happen to know the right part number, for the rectangular ones?  Alternately, is there anyone that's changed the frontpanel designer file to match the circular ones, and has any tips, alignment/size-wize?

glenn

 

[Dyonight]

Yeah I have this but cannot upload it and lost a message it took 10 minutes to write.........

I was saying the template is fits the pushbuttons and leds in the BOM.

https://www.dropbox.com/s/q2seqg56af02hwi/ML12%20layout.fpd?dl=0

Not sure what's the height needed for the standoffs though

The layout is also meant to use with a CAPI VP-Gainswitch Bundle :

http://classicapi.com/catalog/product_info.php?cPath=51_133&products_id=237

Also the classic pointer are highly recommended ( by me )

http://classicapi.com/catalog/product_info.php?cPath=23_39&products_id=374

With those colour inserts:

http://classicapi.com/catalog/index.php?cPath=23_26_27_124

Also if you use Gainswitches, be sure you don't put any standoffs facing upward or you'll have trouble insert the module. Better use female/female standoffs with short screws.

 

[dissonantdissident]

So, I was planning on doing with the VP Gainswitch bundle, but I was planning on doing them upside down, ala the picture of the bundle installed on the Classicapi site:

http://www.classicapi.com/catalog/images/gallery/switches/rotary/VP-Gainswitch/VP-GS-In-4.jpg

If I went ahead and did it that way, could I simply copy the three circular holes(one your file), and center them in the square ones, then delete the square ones?  It seems that would give me properly  aligned holes, for the pushbuttons, without having to alter the rest of the design.  Definitely gonna use the pointers.

Cheers!

glenn

ps- I have 8 1/4" shaft aluminum pointers that I would love to trade for 1/8" shaft CAPI pointer knobs.  I only need 4, so you'd come out the winner, money-wise!

 

[Dyonight]

That's the placement I originally planned too but the back of the gainswitch is too deep and there's not enough clearance between the front panel and the C6 condenser

If you keep the spacing like in the file I sent you, the switch will be just a bit over the condenser and will fit perfectly. Maybe you could try to install C6 horizontally but I don't know if there's room to tilt it enough on the pcb.

Anyway before drilling your front panel (or sending it to front panel express) it is very wise to print the model and try the layout on a masonite board before wasting time and money.

I almost finished a 4u rack with 21 channels and should be able to order the last transformers for the 7 last channel from capi, hoping they get them back in stock soon.

I'll post some pictures of the result when I'm done, should be somewhere in 2 weeks of all goes well!

 

[dissonantdissident]

How's about this:
https://www.dropbox.com/s/lhki878o29gqc2l/ML12_FP%20round%20buttons.fpd?dl=0
I'm doing two channels of 312, with CAPI iron and RED-25s, and the other pair are going towards the Quad Eight family, with Cinemag transformers and the BLU-18s.
glenn

 

[Dyonight]

oh yeah that look nice!

Just to let you know, the following colors match perfectly togheter, coincidence maybe but very nice looking!

Front Panel Designer "Signal Red" -> CAPI "Red" Poly Knob Insert

Front Panel Designer "Pastel Orange" -> CAPI "Amber" Poly Knob Insert

Front Panel Designer "Sky Blue" -> CAPI "Blue" Poly Knob Insert

I used the RED color for the 312 and the Orange for the Quad-like channels, to better illustrate the intensity of the character and they look awesome !

PS: Just had a little fun changing a couple of things the way I have done mine since I know those colors and layout look great here! Maybe you will find some elements that you like!

https://www.dropbox.com/s/4x0x4ssgmcvq1s6/ML12_FP%20round%20buttons%20Suggestion.fpd?dl=0

 

[Dyonight]

Oh yeah on the first model I sent you the dots around the gainswitches match perfectly each steps of the actual switch, and the rounded rectangle hole fits and secure the gainswitch in place.  Maybe you would like to use it since the original dot placement won't match each steps.

 

[Dyonight]

I've updated the last link, the switche will fit perfectly in the hole and the pointer knobs  will align with the dots throught each 12 steps

 

[dissonantdissident]

Cheers!  Waiting for my quote back from Cinemag, for the "Quad Eight" pair.  Got my Digikey order in, and now I just got to get the money for my mouser and CAPI orders!
glenn

 

[Dyonight]

Here's my built once racked.

The first Red row have no transformers yet but I couldn't wait to see how it look once completed!

 

[Dyonight]

Cheers!  Waiting for my quote back from Cinemag, for the "Quad Eight" pair.  Got my Digikey order in, and now I just got to get the money for my mouser and CAPI orders!
glenn

OUPS! If you decide to use the layout I sent you, don't forget to change the label "TX" to the more apropriate "POL" or "INV" or "PHASE" to better match the actual function of your built!

I updated the file just in case!

 

[dissonantdissident]

Thanks for the head's up.  Your's look really sharp!

 

[dissonantdissident]

Finally getting around to putting this all together. The one thing I'm missing is what amp fuse to get. I know I need a slow blow, but not the rating. Any help?

 

[mikefatom]

Finally getting around to putting this all together. The one thing I'm missing is what amp fuse to get. I know I need a slow blow, but not the rating. Any help?

Hey dissonant,

Which power transformer are you using?
How many preamps are powered by the power transformer?
Which op-amps are you using?
I assume you're using the ML12 PSU board?

Cheers,

Mike

 

[dissonantdissident]

Didn't see this response, sorry  :-[. Anyway I think that I've got the whole fuse issue figured out, but, just in case, I'm using a triad 100VA transformer into the ML12 PSU and powering 4 boards. I had an extra fuse for a 6u 500 rack that seemed to be appropriate, and I've fire up the PSU without issue, to trim voltages.

Anyway, I'm about to finish up the build and I had one remaining question, which is what brought me here, today. I'm getting ready to wire the XLR grounds, and I don't know if it is better to go to the chassis ground or to the PSU's star ground point, before the plug. Is one better than the other? The GSSL build I did went to chassis, but it didn't have a dedicated star ground point as an option. At least not one that was clearly labeled.

 

[dissonantdissident]

Well, I went ahead and tied the xlr ground pins to the star ground point and plugged it in. Trimmed the voltages and added the DOAs. Haven't put it through its paces, but it passes audio. The faceplate I ordered definitely won't work, but I'm gonna drill a couple new holes to mount the gainswitches on. DIs will have to wait til I save up a little more money.

 

[dissonantdissident]

Of course, I spoke too soon. After getting it together and racking it, I see that I have 2 channels that're working, but the other two are only passing some audio. Here's the breakdown:

Channel 1: Passes audio, but turning the gainswitch doesn't do anything, until the last position, when it jumps all the way up to feedback city.

Channel 2: Passes audio, turning gainswitch up same as above, but no big jump at final position.

Channel 3: All good.

Channel 4: All good.

Any ideas? I'm surprised there aren't folks on this thread, as DIYRE has started selling the boards, again. I'm gonna check the Litz wiring diagram, again. I did the CAPI litz on the two that aren't working, and their wires are different colors, than the normal 2503s. Maybe I switched a couple around.

Update:

Voltage test points all check out and swapping opamp for tested opamp has no effect. Also transformer wiring looks right, if I'm reading the CAPI specs pdf correctly: http://www.capi-gear.com/catalog/images/gallery/2503/2503-Litz-specs.pdf

By my reading the wiring should be left = right (black = brown, red = red, etc). If that's right, I appear to have them soldered to the correct pads. Builds are all pretty much identical, with the only difference is the two that don't work have CAPI iron and the others have Cinemag. Never had an issue with CAPI iron, before, and so I'm thinking there has to be something else causing the issue.

Update II: Jeff @ CAPI has confirmed that I read the spec sheet correctly, and that I should have the outputs installed correctly. It seems that the gainswitches not increasing the gain is gonna be the only clue. As always, any help is appreciated!

 

[mikefatom]

Of course, I spoke too soon. After getting it together and racking it, I see that I have 2 channels that're working, but the other two are only passing some audio. Here's the breakdown:
[...]

Hey dissonantdissident,

Can you post photos of the two non-working PCBs?  Especially around the Op-amp, RF, and gain switch.  I'm thinking that there could be a problem with the feedback network.  Maybe a shorted/wrong value RF or CF.  Can you double check this?

Also, did you try swapping DOAs from the working preamps to the faulty ones?

You can email me with the photos if you prefer.

Thanks!

Mike

 

[dissonantdissident]

I'm not totally sure how to post pictures on here, but I've attached one picture to this one and will attach another the following post. I have not moved the blu18 over to one of the red 25 slots, but I have tried using a GAR1731 that I know is fine, and the two nonfunctioning ones continued to act the same. Don't think it's the DOA.