Boss PQ-4 Parametric EQ

classic Classic list List threaded Threaded
13 messages Options
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Boss PQ-4 Parametric EQ

spacecase96
Boss PQ-4 Parametric EQ

They stopped making this pedal in 1997. I bought one these back in 1994. I have a Randall RG200 G3 and have added this pedal in the effects loop. It's makes this amp sound like hell's fire with the adjustable Mid and High frequency’s on this pedal. It kinds of adds the same feature Dimebag Darrell had on his Randall Warhead amp with the adjustable Mid frequency. Don't want to see this Gem of a pedal to Disappear.


Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Boss PQ-4 Parametric EQ

Alex
That's double but what would you eliminate to make it true bypass?
I was thinking: Q2, Q7, Q8, R2, R6, R51, R52, C4 and C29.
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Boss PQ-4 Parametric EQ

nocentelli
Delete R49 and leave R52?
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Boss PQ-4 Parametric EQ

Alex
Just seen R52 is 100K and not 1M!
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Boss PQ-4 Parametric EQ

Alex
Another question:
Pres, High, Low and Mid pots are all connected to a 47uF cap going to ground.
From which lug are they connected?
They should be W taper center-tapped pots and I'm not sure how to build (if at all possible) a clone with regular pots.
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Boss PQ-4 Parametric EQ

spacecase96
In reply to this post by spacecase96
I don't know if this helps. Can you use this schematic to reference how to hook up the lungs.
Furman PQ3

Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Boss PQ-4 Parametric EQ

spacecase96
Sorry just googled W Center Tapered Pots I now see what you mean now.
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Boss PQ-4 Parametric EQ

spacecase96
After reading your replies had to pull this thing apart and get some guts shots.






Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Boss PQ-4 Parametric EQ

spacecase96
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Boss PQ-4 Parametric EQ

Alex
Only thing those are Linear instead of W Taper.
Don't know if they would sound the same.
Any idea?
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Boss PQ-4 Parametric EQ

spacecase96
I did skowered the internet for some a100kw found some from China but don't really trust those they did not look right. I did found some duals on eBay http://www.ebay.com/itm/3-pcs-Alpha-100KA-Dual-Stereo-With-Center-Tap-Potentiometer-Pot-15mm-Volume-/300921422458?hash=item461050827a:g:WiYAAOSwabhUVRi9

I did buy 8 of the b100kw from Mouser I am going to do a test and build that boss pq-4 circuit with a solderless pcb board. See how they sound.
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Boss PQ-4 Parametric EQ

Alex
Cool. Let me know how it works.
A layout wouldn't be too complicated.
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Boss PQ-4 Parametric EQ

spacecase96
http://www.eleccircuit.com/audio-loudness-control/

I did some home work. That 47uf cap is basically a loudness control. That 47uf cap give the circuit the extra 3db. That's why all the other parametric EQ or Graphic equalizer only do -15 to +15. In the Boss PQ-4 circuit the add the loudness control which is one 47uf cap and center tap potentiometers. A pretty cool and cheap way to get an extra -3 to +3 in stead of being -15 to +15 you get the -18 to +18.
Loading...