Drip Dual-STA 5167 Limiter

[scott2000]

EDIT: threw it into my rack and now both channels don't work right.

Ugh...  I was excited for you then I wasn't....

Output brings volume up and then down and then up again and you turn to the right.

Can you describe this in a bit more detail?  All I can picture is the hokey pokey...

 

[FarisElek]

Ugh...  I was excited for you then I wasn't....

Can you describe this in a bit more detail?  All I can picture is the hokey pokey...

o

okay after playing around I think i can describe it better. Input increases volume which is a high-passes sounding signal. this is how it worked before too. but the output would bring up the whole signal including low end. it sounded very nice.

now the input works the same but the output actually brings the whole signal down as your turn into the right. when you get about halfway (12 o’clock) the signal is gone. and from 12 o’clock on the signal decreases. no low-end. completely high-passed sounding.

both channels exactly the same. one channel NEVER had a problem. which means both channels are experiencing the same problem. I actually got to hear one of them go out. it kind of just dropped out like a radio losing signal. first it was only channel one and then two went as well.  from huge lush sound to thin weak high passed.

 

[scott2000]

Sounds like some impedance weirdness....

I'm not familiar with how these are set up as it relates to the originals but I'd probably check over the input and output pads...

You did mention that the voltages in the circuits are right on???

 

[FarisElek]

I’ll have to recheck the voltages since it fizzed out but they were right on.

 

[FarisElek]

Extremely interesting development. Went probing around and when I touch the "TO ATTN" point on the pcb that goes to the output attenuator. The bass smacks back and the input works normally. The output turn it down rather than up though.


UPDATE: When I probe the 3 points with a continuity meter that go to the attenuator labeled "com", "to atten" "from atten", Those particular parts of the unit begin working. I probe all 3 separately, the unit WORKS. There is something going on with the grounding! The way it died I'd say it could be one of the resistors that go to ground. But all of the resistors are metal film and look totally fine.

And....If I follow that rabbit hole down. I find that If I do a continuity test on secondary high and secondary low of the transformer separately...I get the sound that I should be getting from those to come through the music I'm putting through the unit. What kind of wacky stuff is happening...?


Final update:

.....

The problem was with my patchbay. When I plugged straight into my converters my signal is perfect. Discovered accidentally.

Goodnight.


Ryan

 

[JMan]

The problem was with my patchbay. When I plugged straight into my converters my signal is perfect. Discovered accidentally.

Goodnight.


Ryan

I was so happy to see this update!  Congratulations!

I *will* eventually get to this build...

 

[FarisElek]

Sage advice: If you re-wired your patchbay to fit your new creation and suddenly it’s signal is messed up...double-check straight to your converters. In my case I built all the xlr to trs cables myself and literally the two of them I was using  both lost their connections to negative on the trs. I’ve been using them for years but this time just happened to be the time they both loosened up.

While troubleshooting I learned that you should connect both CT wires to the left-most choke terminal if you’re using a choke. It fixed my 300 voltage which was under voltage on both channels to about 310-315v per channel which I was able to adjust with the 5k trimmer to the perfect voltage.

Sounds amazing. Even with the solid state psu + choke. On bass I get a really farty saturated bass tones when I crank it. Really thickens mixes on mix-bus. I’m still figuring out how to use it but it’s sounding amazing.


Very curious tho. Is there way to calculate how much compression is happening to a signal just to verify it’s working perfectly? Due to lack of threshold knob it’s hard to figure out how much compression is happening besides the meter.

 

[rob_gould]

Well done!

I've been following this with interest and you really got a raw deal. The thing with the transformer pin! Aaargh! But great that you've got there in the end

Too late now for advice of course, but yes - the issue you described defo sounded like something outside the compressor. It was going to be my suggestion to start bypassing wiring until I read down and saw you'd cracked it.

Enjoy!

 

[FarisElek]

Well done!

I've been following this with interest and you really got a raw deal. The thing with the transformer pin! Aaargh! But great that you've got there in the end

Too late now for advice of course, but yes - the issue you described defo sounded like something outside the compressor. It was going to be my suggestion to start bypassing wiring until I read down and saw you'd cracked it.

Enjoy!

It was a struggle. It was my first project this big. If it wasn't for the transformer problem and the patchbay problem it probably would have been pretty painless haha and saved me a lot of self-esteem.

Okay now that the project is done. I'm noticing my low-end can be pretty damn flappy. I like it...to a degree. But I feel like it could be slightly less flappy/fuzzy. Is this a 6v6 thing? I'm using cheap JJ's because I was able to get them from work very cheap. Using NOS Phillips 12AT7. I may someday go big on the tubes but for now I'm happy to hear what you think is causing the ultra flappy low end and what your suggestions on toning it down a little would be.

It sounds rad on bass...but maybe a little too rad. Not excessive on other sources.


Ryan

 

[JMan]

Any chance you could share some pics of the finished unit?

 

[FarisElek]

It's painfully messy after having gone back a few times. I had to cut a bunch of zip ties I was using to keep the wires in a good place and the last time I rewired the SMA's I didn't pay as much detail as the time first time so I'd like to go through it before I show it off. I'll take pictures when that happens which will be soon.

 

[theposterkid]

Extremely interesting development. Went probing around and when I touch the "TO ATTN" point on the pcb that goes to the output attenuator. The bass smacks back and the input works normally. The output turn it down rather than up though.


UPDATE: When I probe the 3 points with a continuity meter that go to the attenuator labeled "com", "to atten" "from atten", Those particular parts of the unit begin working. I probe all 3 separately, the unit WORKS. There is something going on with the grounding! The way it died I'd say it could be one of the resistors that go to ground. But all of the resistors are metal film and look totally fine.

And....If I follow that rabbit hole down. I find that If I do a continuity test on secondary high and secondary low of the transformer separately...I get the sound that I should be getting from those to come through the music I'm putting through the unit. What kind of wacky stuff is happening...?


Final update:

.....

The problem was with my patchbay. When I plugged straight into my converters my signal is perfect. Discovered accidentally.

Goodnight.


Ryan

Congrats on getting this build finished up! I've been down that road myself, too (with other projects). Everything working with the lid off, and you put it in the rack, and it stops working again.

I want to build a STA but have been scared off by the stories of confusion and the possible lack of accurate documentation. You've encouraged me!

 

[FarisElek]

It's really doesn't have to be as bad as it is. The documentation doesn't follow the current PCB's and it's confusing which parts of the eratta to listen to and which not to. Also theres no schematic. If I could go back with everything I know now I'd do it much different. If you decide to do it, definitely listen to the PSU eratta with choke but connect output transformers B+ straight to choke's left most terminal. Ignore the erattas to the control board and use good quality SMA connectors and cables.

I actually spoke with Gregory and he realizes he needs to be less general with his documentation. He said he's working on an update.


Oh yeah: If you get a case from collectivecases, you might want to ask him to flip the vent on the case around. I flipped mine around but it doesn't exactly go that way. I kind of forced it to. The reason being that the vent is near the PSU which doesn't get hot in my case because my power transformer is on the outside and I'm not using a 5AR4 tube...which I think may not even be possible with two units being powered at the same time. Not sure.

All the heat is being generated at the 6v6 and regulator tubes near the front. They get REALLY hot. After about 30 minutes I could touch the top of the case but it was admittedly pretty hot. When I flipped the top around it wasn't too bad. When I burned in the tubes for a couple hours I used a box fan to pull air away from the unit while I walked away. Came back and the case was luke warm to the touch. For peace of mind I'll probably install a rack fan above it.

 

[JMan]

Do you know when the boards were revised?  I bought one around November of last year.  Any ideas whether that would be the same board as yours, or the "old" one?

 

[FarisElek]

Do you know when the boards were revised?  I bought one around November of last year.  Any ideas whether that would be the same board as yours, or the "old" one?

As you can see it says, "Version 1.2 Corrected” on the control boards. I think they were corrected by the end of 2018. It says the samething on the mainboard. The PSU is a separate board from the XLR board. That's also a newer thing.

 

[JMan]

Ah!  Okay, thanks!  I looked an I also have the version 1.2 corrected board, so I'll be referencing your conclusions above when I get to this build.

 

[FarisElek]

Boy I liked this thing with JJ 6V6, but with Sylvania 6V6GT I like it even better.

 

[JMan]

I'd be very interested to hear your thoughts on the difference between the two.

 

[FarisElek]

I'd be very interested to hear your thoughts on the difference between the two.

Honestly, a little less flat of a response. More beefy and saturated sounding. I sent the same track mono into both sides and flipped them back and forth 30 or so times. their output was matched with a 1khz tone and they were showing the same GR on the meter. I didn't do any extensive measuring beyond that. But the JJ’s comparatively were flatter IMO and sounded closer to the source. In that respect they probably perform better. The Sylvanias burned noticeably hotter too, possibly due to less surface area? That being said, I prefer the Sylvanias. Fat beefy epic tube monster with smooth tube compression was what I was in this for. It won’t make or break the sound but it sure helped.

 

[FarisElek]

Starting to realize some of the voltages are off spec on this build. For instance the original schematic says 282v on the 6v6 plates but I'm at 326v. This isn't something I'm hearing. It sounds great. Just something I noticed while rebiasing after a couple weeks of usage. Is this a problem? Some fender amps have their plate voltages as high as 400v.

Thats pretty much the only voltage that is off more than 8v that I've noticed.