[BUILD] 1176 Rev A - Back to the beginning...

[Rob Flinn]

Baadcode I have had to sort out several projects for people who have bought them "half finished" from the black market.   In my experience this is quite often a nightmare.  Many inexperienced people off load there botched projects when they can't get them working.  I have come across really poor soldering, melted Lorlin switches, dangerous mains wiring etc etc

The latest one has the earth to chassis safety connection made in the following way:    A hole drilled in the case, a thin wire poked through the hole, & a self tapping screw screwed into it !!

 

[dtonthept]

Hey does anyone have a favourite 7824 voltage regulator for this 1176?

Would this one be happy? http://ca.mouser.com/ProductDetail/Fairchild-Semiconductor/LM7824ACT/?qs=sGAEpiMZZMtzPgOfznR9QTB3r8Knl6VZ

It's THE last component I need for my pair... Phew!

D

 

[benlindell]

That one will work great.

 

[baadc0de]

Hooray! It passes signal  ;D

... but ofcourse it doesn't compress. I've seen a few pointers in this thread about these kind of problems, so I'll try to sift through all relevant replies.

EDIT: also, I did the q-bias adjust. It's easy once the compressor doesn't hate you.

EDIT2: it compresses, but i'm a bit confused. it doesn't really sound all that good, easily distorted and a bit band limited. I'll see if I can duplicate the samples some other people have been posting.

EDIT3: sometimes the problem is between the proverbial knobs and chair. Yes, it distorts when you crank the release down, dummy! It seems to have more of a release range than what I'm used to with software (this is my first hw comp) and a little less on attack. I'll get used to this. The sound, on settings that work well, is gorgeous. I'm so happy to have finally debugged this

Thanks to everyone who helped me get through this laborious journey on my first DIY item..

 

[baadc0de]

Hold it... is this all right?

http://jumbofiles.com/lexx6mzl3pvv/gtrpick4.wav.html original
http://jumbofiles.com/crks0exizxay/02-100813_1742.wav.html processed (attack 3, release 6, ratio 12:1, input full, output -12dB).

Is it only my imagination or is only half of the waveform compressed?

 

[mac]

Hey everyone,
just tossing some resistors into Makos new Rev A V1.2.5 boards and came across this anomaly.

there are two R16 on the silkscreen. one on the main board silkscreened as 47k in the sig preamp stage and one silkscreened as 3.6k on the meter board.

R16 is a 100k resistor on the V1.2.5 BOM which I am assuming is the 47k appearing in the mainboard signal output stage. Did this arise from changes as discussed further back in the thread (to be consistent with the changes made after the first 25 units were produced). This is one of the changes Mako was talking about making .....yes?

"R16" on the meter board silk screen is meant to read "R18" yes? and is correct as a 3.6k resistor.

Mac

 

[mnats]

R16 is a 100k resistor on the V1.2.5 BOM which I am assuming is the 47k appearing in the mainboard signal output stage. Did this arise from changes as discussed further back in the thread (to be consistent with the changes made after the first 25 units were produced).

Use the value listed on the BOM and schematic in the signal preamp stage for the 1.2.5 board. The screen layer value is incorrect.

V1.2.5 = serial number 125...get it? It was just dumb luck that the previous board was V1.2.

"R16" on the meter board silk screen is meant to read "R18" yes? and is correct as a 3.6k resistor.

This is just the usual 3600 ohm resistor used with a VU meter to provide the correct deflection for the reference signal. It is marked R18 on the schematic so yes, the screen layer designation is incorrect but in this case the value is correct.

 

[mac]

Hey thanks Mako,

Use the value listed on the BOM and schematic in the signal preamp stage for the 1.2.5 board. The screen layer value is incorrect.

Is this also the case for other values. I note that R12 is 1K on the screen, but 2.2K on the BOM. R30 is also 120k on the screen but 150k on the BOM.

Mac

 

[baadc0de]

How does hfe of the 2n3707 transistors change the parameters of the compression? Can it influence the threshold or preamp gain?

 

[mnats]

Is this also the case for other values. I note that R12 is 1K on the screen, but 2.2K on the BOM. R30 is also 120k on the screen but 150k on the BOM.

Embarrassing. I've corrected the overlay on the documentation. Luckily the printed values disappear once the resistors are mounted!

I've also fixed the link in the file you mentioned in the board ordering thread.

 

[mac]

Hey Mako, 

Sorry dude. Not embarrassing.... without you and your boards I would be breaking drill bits on a home etch right now, instead of stuffing this beautiful looking board!!!

;D

 

[Josiah]

Hello everyone,

I have a quick easy question I hope... Is the Rev A build process much diffrent than the Rev D? I looked at the circuit board overview and it looks like the I/O connections are very similar. I see the 600 ohm T-Pad, 0-12 Input and the EA transformer in the BOM as well. I assume the ratio and meter selections are the same. Is there something diffrent in the calibration process?

Thanks for the advice, I love building these things...they sound GREAT!!! 

 

[Stagefright13]

If you already have built a Rev D then this is almost the same. Different parts mind you. And there is a test point on the board that is for calibrating. But otherwise very similar. And sounds great! If you already have a rev D then this is the perfect compliment to it.

John

 

[baadc0de]

Turns out the asymmetrical clipping and distortion was courtesy of my audio interface. Mackie Onyx Satellite clips the upper half of the waveform. It's pretty obvious after about -8dBFS. It took a better part of the day to troubleshoot, but now that I know how to drive it, it sounds AMAZING. I don't think the 1:20 ratio works correctly, but the 1:12 and below all work great.

 

[Josiah]

If you already have built a Rev D then this is almost the same. Different parts mind you. And there is a test point on the board that is for calibrating. But otherwise very similar. And sounds great! If you already have a rev D then this is the perfect compliment to it.

John

Thanks John for the reply. So far I have built several of the Rev D units with no problems. They all sound great in the studio... Do yo have more specific information on what is different on the calibration side of things. Does the Rev A BOM include the Orange Drop capacitors or is that still a modification part? 

 

[alex81]

Hello guys,
i finally finished my first diy project : 1176 rev A bluestripe clone
I'd like to thank Mike at Hairball and mnats for the amazing kit!!!
I'd also like to thank everybody on the forum for the great advices and info.
I'd was difficult sometimes as i'm a beginner but in managed to solve all the troubles and now it works fine.

I tried it on a snare, it sounds really really well!!! Nice "smack" sound
thanx a lot!!!

ps: here is a pic, it's bad quality, i'll post a better later

 

[evilcat]

Hey Alex, happy for you ! It's good to see more and more french people in here. For me, it's my 1st anniversary !!!
Just for curiosity, what did you put for transistors : 3707 or 5088 ?

Ben.

 

[alex81]

Thanx and happy birthday Ben ;-)
I used 3708, maybe i'll try 5088 if i make another 1176
cheers

Alex

 

[evilcat]

I've made a sort of "shoot out" of components, including transistors : 3708 and 5088. They sound quit different as 3708 are darker, thicker while 5088 are brighter, (a little) more aggressive. I wrote a thread on that with sound samples if you wanna take a look :

http://www.groupdiy.com/index.php?topic=40154.0

Best,

Ben.

 

[alex81]

Thanks for the info Ben, i'll take a listen to the samples you've done and tell you what i think.