..hi guys...i recently bought a vintage Pearl chorus ensemble CE-22...since not a lot of info can be found on the interent 'bout "her"...the minute a laid my hands on it...i already disassembled it!...(having thoughts of cloning this baby..hohoho...)...but to my suprise...it's got the MN3009 bbd...can it be replaced by other bbds?..just askin'..or should i hit ebay...tnx in advance!
It depends... but a MN3007 will drop in and work, it just depends what delay time it has and if the 3007 can provide it unaided with adjustment of the clock.
..tnx scruffie for the quick response...by the way i also noticed the CE-22 has got also an MN3007 bbd inside...it has 2 chorus channels..the first is chorus only..the other chorus channel has a vib. delay...
...when i tested the Pearl CE-22..the vib/delay is not functioning...found some schematic diagrams from the net and it helped me a lot to pinpoint the culprit...the LFO circuit definitely is not functioning...so i replaced a TLO22 opamp and a CA3080 tranconductance opamp...and voila!...the vib/delay is now functioning...
But one thing i noticed with this unit...(i dont know if it applies to all Pearl CE-22s)...mine is somewhat noisy...has an audible whoosing sound...unlike my BOSS CE3 and othe choruses i have which are clean...could be a design flaw?...or some components are old and need to be replaced?...
...is there anything i need to do to at least minimize the whooosing sound?...pls help...i kinda love this Pearl CE-22...tnx in advance!... ;)
..here's the schematic...
...anybody could help?....tnx
Seems pretty standard... got enough filtering... although I can see some pre-emphasis but I haven't spotted de-emphasis yet but i've only glanced.
At that age, you may very well notice an improvement from replacing all electrolytic and especially any tantalum caps.
It may also be noisier from dragging too much delay out of the 3009 and not filtering it heavily enough, once again only glanced, if you have an MN3007 though, try dropping it in and adjust the clock cap accordingly.
Another issue could be heterodyning from having 2 clocks on one board, that can cause excess noise if the clocks interact.
Aren't the enclosures on these plastic too? That's not going to help much compared to the shielding offered by a BOSS CE-3.
The enclosure is similar to our regular pedals...aluminun...so it is basically shielded...i already replaced the MN3009 with a MN3007...and even replaced the other MN3007 with a new one..adjusted the clock trimmer...but got same results...
You could be right, Scruffie, bec the clock circuits are laid out on board side by side...it might cause heterodyning.
I'll take your advice to replace all electrolytic and tantalum caps.
Tnx a lot Scruffie... ;)