EQP-1S5 500 series PULTEC ---- HELP/BUILD thread

[bapa]

Thanks a lot!

I did a reflow on the pins of the grayhill on the low-band, but no change! After some testing with my Capi Lc53a today, the top-freq are behaving in a similar way (volumewise). On the lowband, the AA at 11-12 has the same volume as the Lc53a cranked. The AA´s a lot hotter. I probably wouldn't think that much about if it wasn't that the lowband-pots are very aggressive.  At just 8 a lot is happening (again volumewise). I´m missing a more gentle slope! Perhaps the unit is as should.
Haven´t done any frequency analyzing before. Let me check on that, any recommendations on software (preferably free) doing so?

Cheers

 

[diylan]

I've been getting a low frequency oscillation, only on occasion, when making huge boosts in the LF band (ie. boost 10, atten. 0). The feedback is at a really low frequency, around 5.5hz, and has some harmonic distortion that creeps up above 20hz.

It wont do this on it's own, only when triggered somehow by the signal running through it. Once I turn the boost down, it will go away. I've tried a couple different opamps to no avail.

Any ideas? Or should i just expect weird things when I crank it all the way up?

 

[zendrum]

I made up a recall sheet for the EQP1S5. I use my pair a LOT, so having a recall sheet was necessary. If anyone else could benefit, please feel free to use and share.

 

[DDay]

I’ve been using the EQs for a while now and absolutely adore them, such amazing work from everyone.
My knobs have gotten a little loose over time.. just wondering if you knew where to buy similar sized replacements?
Many thanks

 

[Dansammartano]

Hi! Just put together a pair of the newest versions (Sept 2019 rev) and had an issue with one of them where some but not all of the frequencies on the high freq boost don't work. When they're selected, audio still passes through, but the boost pot doesn't do anything. Before I take it apart, what should I be looking for that would cause it to bypass the filtering on those selected frequencies (ie does it sound like a problem at the switch or the caps or grounding issue, etc)? The other one works perfectly (and sounds amazing!), so not sure what I did wrong...

Thanks! 

 

[nielsk]

likely a bad solder joint or bridge. Often on one of the film caps.
The only way to really see is to remove the filter board, it is not too difficult.
Remove all switch & pot nuts & front panel. De-solder the board to board pins or simply heat up the 3 pins together and gently lift one side, then the other 3 pins, and after a few times it will lift off. It is easy to suck the solder out of the holes then for re-assembly.
Then you can easily lift out the filter board.
The last ditch is to check the inductor, make sure your DVM is not in BEEP mode. You should see under 100 ohms between pin 1 and each tap on a naked one, I would have to check one to see what they read in circuit bit it will not be open and it will not be 0

 

[Dansammartano]

The last ditch is to check the inductor, make sure your DVM is not in BEEP mode. You should see under 100 ohms between pin 1 and each tap on a naked one, I would have to check one to see what they read in circuit bit it will not be open and it will not be 0

Thanks Niels! That was super helpful. I think the inductor might be the issue. When measuring from pin 1 to pins 2 through 4, i get the correct ohm readings, but starting at pin 5, it reads zero, and continues being zero through pin 7.  Seems like there is a loss of continuity between pins 4 and 5 of the inductor. The joints all look good, so I'm guessing there's just an issue with the component itself.  To rule out other causes, I checked all the switch and cap joints with the meter and there were no shorts or continuity issues. Also each position on the switch passed current to the proper pin without shorts.

 

[Jpg453]

I finished building the EQP-1S5 kit last week and it turned out great! Really cool EQ!

I built the Rv3 (2019) version, and I couldn’t find any photos of that particular kit, so I wanted to share a some here. If you’re building the 2019 kit, keep in mind that the build guide and sorting sheet on this site were written for the previous version (2017), and the sorting sheet and BOM won’t match the values or positions on the PCB. Everything should work out if you just follow the PCB, tho!

I included a close up of the amp board. For Rv3, the two “optional” caps are C46 and C47. I’m using a traditional 2520-type op amp, so I left C46 (100pf or 120pf cap) empty, and installed a jumper (just a tiny piece of excess lead) in C47.

I had some questions along the way, and Dimitri was incredibly helpful and generous with his time! I’m sure I wouldn’t have bugged him as much if I’d been able to find some photos and/or a support thread for the Rv3 build specifically. Hope these are helpful!

 

[cycli]

Anyone selling spare kits or know where I can get them these days if still available anywhere?