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Project Specific Discussions => Filters/Equalizers => Topic started by: Vangetti on February 25, 2019, 12:16:58 PM

Title: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on February 25, 2019, 12:16:58 PM
Hi Everyone,

I just finished putting together my EQ1, but I have an issue. There is a 60 Hz hum that I can't figure out how to remove. I double checked that my solder joints were solid and tried to troubleshoot the unit with no luck. I also replaced the tubes, but it wasn't the solution. I could boost the 60hz hum with the EQ, so the hum must be going to the preamp tubes.

Would anyone have any idea of what the problem could be?

Perhaps a bad filter capacitor or the power transformer? I fed my guitar through the EQ1, and it did sound nice, but the 60Hz hum is annoying.

Images
(https://i.ibb.co/McHvL9B/EQ1-pic-1.jpg)
(https://i.ibb.co/RYQ7vGs/Eq1-pic-2.jpg)
(https://i.ibb.co/Tgpr6mW/EQ1-Hum.jpg)


Audio clip
https://clyp.it/zpvxi2xa?token=156ff51237ebecbfc3261e4f58a7af30
Title: Re: Drip EQ1 Gen 4 - 60hz Hum
Post by: Rob Flinn on February 25, 2019, 01:51:56 PM
Check you have your grounding correct.
Title: Re: Drip EQ1 Gen 4 - 60hz Hum
Post by: Vangetti on February 26, 2019, 11:57:09 PM
I'm using the continuity test mode on my multimeter and I'm getting a 0.00 reading. When I put my ear up to the transformer the noise coming from it is the same that I hear outputting to my speakers.
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Knotty on March 05, 2019, 04:53:55 PM
I had that same issue on version 2 years ago. I think I fixed the issue by disconnecting a front panel ground. I think there was a ground wire (to be wired to a star ground) for each front PCB. I disconnected one. Even though it was reading 0 ohms to ground, I think it was creating an issue since both front PCBs were also connected to each other via a ground wire. So, maybe try that and see if it helps. Sorry my memory isn't serving me fully right now haha

I did end up buying another one that someone else built and it had the same issue, I repeated the fix I did on mine and now they're both silent. Good luck!
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on March 07, 2019, 07:20:48 PM
Thanks for the info! I think both of my front panel PCBs are connected to ground via the 2 SMA cables. Should I be grounding them to the star ground? The only things I have connected to the power star ground are the  CT, mains ground and PCB ground.

For the audio ground, I have both xlrs grounded and the audio ground from the PCB.
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Knotty on March 11, 2019, 02:42:34 PM
Thanks for the info! I think both of my front panel PCBs are connected to ground via the 2 SMA cables. Should I be grounding them to the star ground? The only things I have connected to the power star ground are the  CT, mains ground and PCB ground.

For the audio ground, I have both xlrs grounded and the audio ground from the PCB.

Ah yeah, I didn't think about the SMA cable. The old ones didn't have those so it was a little easier to experiment. Yeah, not fully sure on the ground scenario for the V4 board without looking at a more detailed schematic. if there are any jumper wires for connecting ground you could try those. But those might not exist. You could try just disconnecting the front panel, one SMA at a time to see if disconnecting one has an effect on the hum? Could point you in the right direction. That is, ONLY DO THAT ON LOW VOLTAGE SIGNAL SMA CABLES. You don't want to mess with pulling a high voltage line that's live. But the signal going to the front should only be signal. That could help you pinpoint it to either board. If its still there, then its an issue somewhere else.
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on March 12, 2019, 01:31:50 PM
That's a great idea. I'll try that and see if the buzz/hum is coming from the front panel.

Thanks!
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on March 13, 2019, 12:24:04 PM
Unfortunately, the buzz still happens even after both front panel boards are disconnected from the main PCB.
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Knotty on March 13, 2019, 07:53:58 PM
Unfortunately, the buzz still happens even after both front panel boards are disconnected from the main PCB.

Ok, that's good. Now we know it's not the front. Are both of those ground wires soldered to the back of the PCB the same ground plane? If so, it could be those two ground competing. Although I can't really see where they're going.
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: scott2000 on March 14, 2019, 07:32:44 AM
Maybe something wonky with the heaters?? Is there any documentation on this build?

Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on March 15, 2019, 07:22:25 PM
Ok, that's good. Now we know it's not the front. Are both of those ground wires soldered to the back of the PCB the same ground plane? If so, it could be those two ground competing. Although I can't really see where they're going.

I have three wires attached to the star ground.

IEC(18 Gauge Ecowire), Transformer (Red/yellow wire), PCB(18 Gauge Ecowire).

For the audio ground, I have both XLRs and the PCB audio ground.

Maybe something wonky with the heaters?? Is there any documentation on this build?

Unfortunately, I don't have any documentation for the build. I just have a few videos that I found online and pictures on the drip website. Also, some pictures I found on Reverb.
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on March 22, 2019, 05:28:41 PM
Here is a top view of the unit.

(https://i.ibb.co/9pZ8rjS/EQ1-Top-2.jpg)[
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on March 28, 2019, 02:05:18 PM
Would it make a difference if I drilled my own ground hole instead of using the one provided? It looks like the one predrilled into the back panel is a little too big for my #6-32 screw. Could that be a cause of the hum?
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Gustav on March 30, 2019, 12:29:00 PM
Would it make a difference if I drilled my own ground hole instead of using the one provided? It looks like the one predrilled into the back panel is a little too big for my #6-32 screw. Could that be a cause of the hum?

Check resistance to chassis from someting going to that point - if its more than a few ohms (would be a lot more, possible an open, if the screw is not making contact) .

Gustav
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on April 02, 2019, 12:08:16 PM
There is about a 0.6 Ohms resistance when testing one ground to another. Any ideas?
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on April 05, 2019, 02:15:03 PM
I drilled a new ground hole and got a bit lower resistance when checking between grounds, but it looks like it did not make a difference. I'm not sure if the issue is with the case anymore all the grounds look like they have good continuity.
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Zjcc56 on April 07, 2019, 08:11:03 PM
So It looks like in the schematic that the heaters have a center tap and it doesn’t look like you have a center tap from your power transformer so a possible solution would be a artificial center tap. Some good reading about it:
http://www.valvewizard.co.uk/heater.html
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: scott2000 on April 07, 2019, 11:33:35 PM
The original uses AC for heaters ...  this  Drip board uses DC for the heaters.... ??


What is the power transformer being used on this build??
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on April 08, 2019, 04:39:28 PM
Yeah, the version 3 ran on AC, but the gen 4 board is now on DC. I'm using a Hammond 270BX transformer. The CT is supposed to be the red/yellow wire that I have lugged to the star ground.
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on April 09, 2019, 06:19:27 PM
I'm losing it I guess. I just looked at the DRIP site and see there is some documentation on this build???////At least some initial build stuff//

https://www.dripelectronics.com/drip-eq1-pultec

.... I'm sure I didn't see anything before.....

I ran into the same scenario. I would google the drip eq1 and found older documentation. The schematics that are uploaded on the drip website are the original Pultec schematics.

(http://www.advancedaudiorentals.com/docs/eqp-1a_schem.jpg)

I don't understand why on the PCB silkscreen has  .1/220V capacitors in the 6.3 power section,  but on the finished builds on drip's website, they're not there? Do you think I should put them in and test it out? Also, would it be better to use the 6x4 rectifier tube instead of the 1N4007 diodes?

I found a build that someone completed with only 2
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: scott2000 on April 09, 2019, 07:44:16 PM


I don't understand why on the PCB silkscreen has  .1/220V capacitors in the 6.3 power section,  but on the finished builds on drip's website, they're not there? Do you think I should put them in and test it out?



Just guessing without knowing where they connect but probably not necessary if they're just extra caps for the bridge......here's some discussion on this....

https://electronics.stackexchange.com/questions/14250/what-are-the-advantages-of-full-wave-bridge-rectifier-with-capacitors-parallel-t


 Also, would it be better to use the 6x4 rectifier tube instead of the 1N4007 diodes?


Shouldn't matter.... I guess that's subjective but it does the same thing....

I ran into the same scenario. I would google the drip eq1 and found older documentation. The schematics that are uploaded on the drip website are the original Pultec schematics.


I was referring to this back panel guide....

https://ws.onehub.com/workspaces/894291/files/2343174797

attached PDF

Just in case .....



has to be something ....You'll figure it out.....

Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on April 10, 2019, 01:03:14 PM
I think you're completely right about the capacitors in the 6.3V heater section.

I'm really starting to think that I'm getting all this buzz/humm because my 6.3v heater is not grounded. With the transformer I was using, there doesn't seem to be a CT for the 6.3v 2A  section. Do you think I should add an additional to connect HEAT GND on the pcb to the main power star ground?

(https://i.ibb.co/51z2zJW/Eq1-pcb.jpg)
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: scott2000 on April 10, 2019, 03:25:13 PM
I wouldn't. It's already set up for your transformer without CT......I'm not sure what the deal is with the different options....Maybe for AC heaters too..... ?? But IDK.....

I did read some Pin 1 issues on some Pultec builds....

Have you tried reaching out to Gregory at Drip for some direction???

Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on April 10, 2019, 06:24:06 PM
I wouldn't. It's already set up for your transformer without CT......I'm not sure what the deal is with the different options....Maybe for AC heaters too..... ?? But IDK.....

I did read some Pin 1 issues on some Pultec builds....

Have you tried reaching out to Gregory at Drip for some direction???

Unfortunately, it's really difficult to get in contact with Greg. I've sent him a few e-mails, but I haven't heard anything back.

Could you elaborate on the Pin 1 issue?

After looking at the pictures on the Drip website, I can see that there is a wire going from heater GND to something... It could be the star ground, but it's really hard to tell.  I looked at the traces on the back of the PCB and it looks like the 6.3V - does not discharge to earth ground without that Heater GND connection as it should from the original Pultec schematic.

There was a video where Greg mentioned that the star ground should consist of the PCB ground, mains ground and the CT, but wouldn't the PCB already be grounded by the aluminum standoffs used to mount the board to the enclosure? Maybe he was possibly referring to the heater ground?

(https://static1.squarespace.com/static/55ffece6e4b0d6cbe1baee3e/t/5a770a0cc830259c53c728dd/1517751117191/IMG_7730.JPG?format=1500w)
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: scott2000 on April 10, 2019, 10:58:30 PM
Interesting...... Yeah I think that may have been what I noticed was different between his and yours a bit back...
....And yours has the one pcb ground spot connected where his doesn't......

The original Pultec schematic has ac heaters so, it's different but, ...... I really don't know how this is set up.....Is there continuity on the pcb from those two grounds on the pcb??? Guess it makes sense with no center tap///??


Oh... Pin 1 issue////
Pin1 of input xlr.....Lifting it to see if it helps.....Grounding it directly to the chassis there I think was a solution to  some of those issues..... Different builds but it's all relevant to some degree....Or not........

I have to admit, looking at some of the info, I think I would be confused about many things as well without a bit more documentation...

Like those unused caps by the diodes...do they have something to do with regulation???...etc..... ....

I'd personally feel better with a point to point.....lol....

But I really haven't looked too close..... Sure is sweet.....
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on April 12, 2019, 12:00:53 PM
I tried the Pin 1 fix, but unfortunately, it didn't work. I also tried grounding the heater, but no luck. This is a real mystery to me. I'm stumped... When measuring my voltages, I'm about 20 volts away from the target on multiple test points.
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: scott2000 on April 12, 2019, 12:52:16 PM
Can you list these ??? 

Maybe an error somewhere  in hookup or component value.....



Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on April 19, 2019, 11:30:54 AM
I took a look at the components that I put into the board, but everything looks correct. Do you think I should try fitting the .1/220V capacitors in the 6.3 power section?
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on April 26, 2019, 06:15:35 PM
These are all the parts on the main board.

TRIMMER 100 OHM 0.5W PC PIN TOP
RES 2.2K OHM 1W 1% AXIAL
RES 1.00K OHM 1/2W 1% AXIAL
RES 4.7K OHM 0.6W 1% AXIAL x 2
RES 1.00M OHM 1/2W 1% AXIAL x 2
Resistors - Through Hole 1W 500ohms .1% x 2
Resistors - Through Hole 1/2W 365ohms 1%
Resistors - Through Hole 1watt 240ohms 1%
Resistors - Through Hole 2watts 62Kohms 1%
Resistors - Through Hole 1/2W 200Kohms 1%
Resistors - Through Hole 360ohms 1% 50PPM x 2
Resistors - Through Hole 1W 200Kohms 1% x 2
Resistors - Through Hole 620 OHM 1/2W 1% x 2
Resistors - Through Hole 43Kohms 1% 50PPM
RES 953 OHM 1/2W 1% AXIAL x 1
DIODE SCHOTTKY 40V 5A DO201AD X 4
DIODE GEN PURP 1KV 1A DO41 x 2
IC REG LINEAR POS ADJ 5A TO220-5
CAP MICA 270PF 5% 500V RADIAL
CAP ALUM 47UF 20% 450V RADIAL x 7
CAP ALUM 10000UF 20% 10V RADIAL x 3
CAP ALUM 47UF 20% 50V AXIAL x 2
CAP MICA 20PF 5% 500V RADIAL
Film Capacitors 0.003uF 1.0kV 3% MPP L/S=15mm
Film Capacitors 400VDC 0.1uF 5% MPET L/S=10mm x 3
Film Capacitors .22uF 630V 3% MPP L/S=15mm

I just double checked it and it looks like it's all correct.

I removed the PCB ground wire, but I still had the issue. I also tried the heater ground connection, but it didn't do anything as well. I don't know why my voltages would be off. I used the highest tolerance capacitors and resistors I could find. It's possible that the original was built for 5% resistors, so my values are off.

Could it be the wires that I used to hook up the IEC? They are the super thin eco wire with not much insulation. I also applied heat shrink tubing to the transformer. Do you think that the heat gun might have loosened up some plates in the power transformer?
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: scott2000 on April 28, 2019, 09:38:40 AM
Have you seen this video?

https://vimeo.com/277697075

Is it relevant to your build
??
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: Vangetti on May 01, 2019, 04:53:33 PM
Have you seen this video?

https://vimeo.com/277697075

Is it relevant to your build
??

I just watched it again. He said that the 3rd ground wire connects to the PCB power supply? I'm not sure exactly what that means. I'm assuming it's the hole labeled power ground on the PCB, but I already had a wire there.
Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: scott2000 on May 01, 2019, 05:12:57 PM
yes....I think you already have it..... but I think he may have used the heater ground instead.......??? maybe less of a ground loop???idk though... ......

Do those two pads show continuity???

But you already tried that spot anyhow didn't you??

you could try twisting up your ac wires a bit more.....those coming from the iec for example (seem to be kinda just lying around and could be shorter maybe??) .....maybe wouldn't hurt to twist the yellow 5v lines........ your xlr lines etc.....

I guess chopsticking the wires around may be able to tell you if anything changes too....

is that lamp circuit AC???



Title: Re: Drip EQ1 Gen 4 - 60hz Hum / Buzz
Post by: denov on June 23, 2019, 08:42:14 PM
Vangetti,

Did you find the issue?  I just finished building a pair of them and getting what sounds like the same type of hum.