Newbie builds Classic Audio Product's VP26 and VP312DI

[Ptownkid]

Unreal. This is a fantastic thread Chunger and you have done a wonderful job with both the detail and the quality of the pictures.

Excellent, excellent work!!!

 

[canidoit]

Those pics really show how great the unit look!

I didn't think these units look that great until I have seen your pics.

Are you using proper lighting and also photo retouching on the pics? What camera are you using?

Thanks, I do the best I can with what I have.  You'd be shocked how cheap my setup is.

I'm mostly running some old, obsolete '90's vintage Nikon SB28 flashes and I have one Alien Bees monolight. . . a couple of umbrellas and some Alien Bees Cybersync radio triggers.

For camera, I'm just running a bottom of the barrel Canon Rebel XTi with a 17-55 f2.8 lens.

For the set shots, I'm using some cardboard boxes, pieces of paper, painter's tape to make something that resembles a light box, and found some paper from an old drawing pad to make a "seamless white" backdrop. . . and I'm using those 3 old Nikon flashes.  For the typical "in progress" photos, I use 2 umbrellas cross light and the Alien Bees monolight to blast my ceiling for fill.

I had rented 60mm and 100mm macro lenses for my friend's product shoot.

I've been contemplating upgrading to a "proper" camera and lighting setup and periodically go online, spec and price rig.  Just haven't had enough paying gigs or potential gigs to justify the purchase yet, so I run what I have and try to squeeze the most I can from it.

I was really hoping that you would have said, I am using the mobile phone camera in my nokia and a few torches

Then atleast I would feel that there was hope that I would ever reach those quality pics.  8)

Well done mate, you have really raised the benchmark. It looks really professional! You should take up product photography for paid work.

 

[chunger]

Well, on to the next thing I guess.  I picked up another VP26, another VP312 kit, and a pair of Igor's F76 51X 1176 kits to try out next.  Better get my PSU built soon 

What fun stuff come January!  I'm searching for a pair of nice EQ's to build and I should be good to go for a while.

 

[jsteiger]

Hi 'Chunger,

Your most recent product pics are sick. Very, very pro looking. I am a little embarrassed when I look at my site now.  ???  Maybe I should hire you to take a few beauty shots.

Keep up the outstandingness! Hey, that ain't no word. 

Cheers, Jeff

 

[canidoit]

Well, on to the next thing I guess.  I picked up another VP26, another VP312 kit, and a pair of Igor's F76 51X 1176 kits to try out next.  Better get my PSU built soon 

What fun stuff come January!  I'm searching for a pair of nice EQ's to build and I should be good to go for a while.

Are you looking for lunch box builds?

Drips have the pultec EQ which I would have jumped on, but I ended up with the EQN since it was released first.

Igors got some sontec mastering EQ coming out soon apparently which sounds very promising.

 

[chunger]

finally got to power up the 2 boards. . . good news is the VP312DI is up and running great. . . bad news is the VP26 isn't running.  I'll have to wait for some holiday madness to pass before looking more into it.  Luckily I have a lot of images to refer back to.  I suspect highly that I buggered the push switches (sw2, sw3, sw4) when I tried to de-solder/re-solder.

I may have to hit up a friend to help me trace and diagnose.

 

[jsteiger]

finally got to power up the 2 boards. . . good news is the VP312DI is up and running great. . . bad news is the VP26 isn't running.  I'll have to wait for some holiday madness to pass before looking more into it.  Luckily I have a lot of images to refer back to.  I suspect highly that I buggered the push switches (sw2, sw3, sw4) when I tried to de-solder/re-solder.

I may have to hit up a friend to help me trace and diagnose.

Good news on the VP312DI! 

Not so good on the VP26.    The only real issues that I have heard about with the VP26 build is the pushbutton switches. Usually, a good re-flowing of those solder joints does the trick. Like you mentioned, I would start there.

Cheers, Jeff

 

[chunger]

Ok. . . good news is the VP26 is working.  I don't think there was anything wrong with the board even though I re-flowed the push switch solder joints.  I installed the APP2050E op amp and it worked fine on the VP26.  Looks like I managed to brick 2 GAR2050's and 2 GAR1731's as well.  I need to go back and investigate where I went wrong on those op amp builds.  I thought for sure I had security in numbers, but apparently, I'm doing something very consistent but wrong.  If anyone's able to look at my op amp builds with a fine-toothed comb and spot an error, please let me know.

My task now is to trace the op amps.

On the 1731's I double checked all of the recommended tests on the instruction manual I guess those are the most common shorts.  Both units did not have these problems.  I noticed powering up both 1731's again that Q8 gets very hot very quickly.  One of the 1731's pops when mute is activated.

I am at the end of my knowledge so further tinkering on my end will lead to bad things.  I'm going to step back until well reasoned actions can be taken.  I know Gary monitors this thread so I'm hoping he might be able to chime in on some more specific tests to narrow down the problem area.  In the meantime, I need to order up a few more op-amp kits.  A few projects I see myself taking on in the future require me to be able to successfully assemble these reasonably priced op amps with regularity.  I wonder if I used too much heat and fried some transistors.

Back to holiday family drama. . . I have these things out now so every time I walk by, I can re-check for something obvious.  I guess I can also rig something up to power up the op amps outside of the preamp board for tracing purposes.  That's something I can certainly do.

 

[mikefatom]

Ok. . . good news is the VP26 is working.  I don't think there was anything wrong with the board even though I re-flowed the push switch solder joints.  I installed the APP2050E op amp and it worked fine on the VP26.  Looks like I managed to brick 2 GAR2050's and 2 Melcors as well.  I need to go back and investigate where I went wrong on those op amp builds.  I thought for sure I had security in numbers, but apparently, I'm doing something very consistent but wrong.  If anyone's able to look at my op amp builds with a fine-toothed comb and spot an error, please let me know.

My task now is to trace the op amps.

Having built two gar2520s and gar1731s, I can't think of anything that you would have consistently done wrong with all four!
Which opamp did you use to test the VP312?

Good luck!

Mike

P.S.: The pictures in your posts are absolutely unbelievable btw!  Great job! 

 

[chunger]

VP312DI has the APP2050E inside.  There's gotta be a bridged solder joint or something on the op amps.  I'll have to go back through the instruction set and test the most common fail points.  The only other thing I can think of is too much heat on the transistors, but I'm using a temp controlled soldering iron.  Maybe my technique is off?

On VP26, I tested continuity on the push switches and they all looked good, so I re-flowed the solder joints per Jeff's suggestion, and there were no changes (still didn't run).  I removed the op amp and tested the + - voltages at the milmax sockets and I was getting correct power.  Swapping in the APP2050E brought it to life, so I knew there was something wrong with my op amp.  I swapped all 4 of the ones I built through the unit, and none worked 

 

[chunger]

Gary emailed support and by superior powers of remote diagnosis suggested I check Q7 and Q8 (big transistors).  3 of the units had swapped BD139 and BD140 transistors.

I have 2 GAR1731's now up and running and 1 GAR2520 up and running. . . one bricked 2520 to diagnose.  HAPPY NEW YEAR!  I was a bit depressed about the 0-4 batting average a few minutes ago.  Now I'm 3-1.

 

[Piotr]

Happy New Year to all !!

Congratulations for your different building threads. What a pleasure it is to see a precisely detailed build history. If only some commercial units benefited from this level of documentation... I guess that's not going to happen. Manuals from the 70's are a long gone treasure !

DIY power !!! Cheers from France, Piotr.

 

[chunger]

Well, after the recent op-amp set backs, I wanted to get right back on it, and get the confidence level back up a bit, so I knocked out another VP26 + GAR2520 last night, and this time, with the exception of mis-placing a BC550 and having to de-solder/re-position it on the op amp, everything worked perfect the first time!  My hack PSU is holidng up.  I'm hoping these pre's don't draw anywhere near max spec so I can run 4 on my little tester power supply to do some studio tests soon. . . one more VP312DI and I'll head in for a session.

 

[jsteiger]

...I'm hoping these pre's don't draw anywhere near max spec so I can run 4 on my little tester power supply to do some studio tests soon...

'Chung

A VP26 driving a 600 ohm load will draw around 51mA per 16V rail. No where near the 130mA max. 

A VP312DI will draw around 92mA with an active HiZ Plug-In and everything running only on the 16V rails. Still below VPR spec with a little headroom to boot. 

Cheers, Jeff

 

[chunger]

Finally got into the studio with 4 preamps. . . 2x vp26 and 2x VP312DI.  I was a bit pre-occupied transporting and poking at this new acquisition. . .

But that's a different story. . . the studio I currently have up and running uses an MCI JH 600 which has been working well as a fairly down-the-middle console.  Goreski is local and we have solicited him on occasion to come do major service on the console to get it up and running little by little.  I had to be opportunistic when another console became available and picked it up @ $1,500.  Plans had always been to build a studio in my house as well because I have a nice high-ceiling room.  All wiring is already in the walls as I installed it all when I built the house.  Just haven't had an excuse yet to get it up.  Maybe this is the impetus and the this new JH636 can be the centerpiece?  Don't know.  I have to learn how to work on it and it'll be a steep learning curve.  Currently, with the exception of some dead channels, the console is working all the way up to the main fader at which point the VCA automation is doing something weird, and we lose audio, but I was able to help swap out a few of the dodgier channels in the current running console and shelve console restoration for a later time.

After that, I was able to plug in the new preamps and record some drums for testing. . . the 2 configurations that really stood out to me were the VP312DI running APP2520E op amp at 24 volts. . . and then the VP26 with GAR1731 on drum overheads. . . wow.  What a treat.  The smaller transformer is tight and focused and the Melcor clone worked really well in our system to give a nice sweet top end to the cymbals and still give a nice mid-forward punch.  The bass is full but contained.  I didn't get to test all configurations, but didn't like the 7131's as much on the VP312DI. . . should test GAR2520 in the VP312DI sometime to hear it.  This test was very critical for me because now I know better how to fill out the rack.  Probably

2x VP312DI w/ APP2520E running 24 volts
2x VP26 w/ GAR2520
2x VP26 w/ GAR1731

What a great little box of sonic goodness!  Very satisfying to hear something you built yourself run and kick @ss.  The hacked together power supply also did well.  

I guess it was able to drive the ~291mA current draw without much issue.  I have a 22-0-22 30VA toroid coming in from Avel as well as a 50VA version that I think can still fit in the single space 51X slot.  All this while awaiting the official GDIY PSU metal.

 

[chunger]

trying to redeem my bricked GAR2520 by jumping right back in. . . this build does not have BD139 (Q7) and BD140 (Q8) reversed and worked great right off the bat.  1hr 10min. build time still being very cautious and photographing along the way.  I am in no position yet to get over-confident.  But, I wanted a photo set for my records that had every component correct.

I think my soldering technique is improving, and the back side of this PCB is much better than previous builds.

 

[gar381]

chunger

Your builds look better and better !
They are looking almost as good as mine
and I have built over 150 of them !!!  One suggestion.....
Tuck the 5.6 ohm resistor lead (R11) behind the DB139.  It will help
you not to create a short between the resistor lead and the twist
at the top of D1 diode pair when you insert the DOA in the millmax socket.

BTW...  1 hr 10 min is a perfect time !

LOOKIN GOOD my friend !!

GARY

 

[Winetree]

I really like the Rack mount P.S.U.
I'd like to build one. The picture explains a lot.
Did you use the higher amp version of the JLM power supply?
Any pictures of the front metal pieces. Did you cut them out?

 

[chunger]

I used the higher amp version for the JLM powerstation even though the transformer I used wouldn't even come close to being able to supply enough to get close to the limit.  I thought I might re-purpose the power supply later, so I built the "biggest" option

The front panel and L-brackets were purchased from the usual 51X suspects and I hacked out the faceplate myself w/ a hand drill and dremel.

Please be aware, this rack-mounted PSU cannot power the entire rack to 51X spec.  The VP26's that occupy the majority of my particular rack are well below spec in terms of current draw, so I was able to run quite a few of them on this temporary PSU solution.  Bigger transformers or possibly separate JLM PSU's for 16V and 24V rails would allow for more capacity. 

 

[Pliplo]

Awesome work Chunger! My goods from CAPI arrived some days ago and i went for 2 VP312DI's... so far im 1/2... but it would be 0/0 if it werent for your amazing guides! I was thinking since i got 2 more and 4 VP26's to go that i could continue your legacy here since i got the newer pcbs, but i dont know if its gonna be useful to someone and of course i dont wanna step in your toes, its just i've been taking advantage of your documentation and bothering Jeff A LOT! so i wanna give something back hehe

I wonder... who has the op-amp record time?