Pearl Chorus

[rocker-D82]

http://experimentalistsanonymous.com/diy/Schematics/Chorus/Pearl%20Chorus.gif

Anyone know this stomp? Comments? Is it comparable with Small Clone?

I can realize a PCB layout. The chips can be changed with Shanghai Belling cheapest compatible pin-to-pin ( http://www.smallbearelec.com/Search.bok?category=ICs+Delays+and+Echo ). It will be a good chorus with a low cost.

[cd]

The Pearl has far more in common with a BOSS CE-2 than a Small Clone.  If you need cheap and good, the Danelectro Milkshake is tough to beat.

[rocker-D82]

The Pearl has far more in common with a BOSS CE-2 than a Small Clone.

I found the schematic of CE-2 and the two pedals are very close. Do you think it's possible to obtain a good sound by that cheapest chip?

[Mark Hammer]

The Pearl Chorus (circuit board CH-2) is very close to the Boss CH-1.  Both have a delay-tone control, as well as a mix/blend control for making the chorus effect softer.

The major differences between the Pearl and the Boss CH-1 are that:
1.  The CH-1 uses an MN3007/MN3101 and the Pearl uses an MN3207/3102.
2. The CH-1 has stereo (sum and difference) outputs and the Pearl just has the traditional mono delay+clean sum output.
3.  The CH-1 lets you have less delay signal but does not let you have more delay than clean.  The Pearl's mix control lets you have vibrato also (all delay, no clean).
4. The Pearl uses a single transistor input buffer, and regular 4558 op-amps, while the Boss uses a M5218AL op-amp for the input buffer and for the rest of the audio path.

If you build the Pearl without all the electronic switching, it will be a good (and much simpler) chorus pedal.

[cd]

The Pearl has far more in common with a BOSS CE-2 than a Small Clone.

I found the schematic of CE-2 and the two pedals are very close. Do you think it's possible to obtain a good sound by that cheapest chip?

With the MN3207 you mean?  You can get a good sound or a crappy sound with that chip.  IMHO the LFO, pre/post filters, and clean/wet mixing is far more important to a good chorus sound than the actual BBD used.

[rocker-D82]

The Pearl Chorus (circuit board CH-2) is very close to the Boss CH-1.  Both have a delay-tone control, as well as a mix/blend control for making the chorus effect softer.

The major differences between the Pearl and the Boss CH-1 are that:
1.  The CH-1 uses an MN3007/MN3101 and the Pearl uses an MN3207/3102.
2. The CH-1 has stereo (sum and difference) outputs and the Pearl just has the traditional mono delay+clean sum output.
3.  The CH-1 lets you have less delay signal but does not let you have more delay than clean.  The Pearl's mix control lets you have vibrato also (all delay, no clean).
4. The Pearl uses a single transistor input buffer, and regular 4558 op-amps, while the Boss uses a M5218AL op-amp for the input buffer and for the rest of the audio path.

If you build the Pearl without all the electronic switching, it will be a good (and much simpler) chorus pedal.

1. Is MN3007/MN3101 better than MN3207/3102.
2. Is possible to make an inverted phase stero effect to Pearl Chorus?
3. I like Pearl for this!  
4. What kind of solution is better?

[Mark Hammer]

1. Is MN3007/MN3101 better than MN3207/3102.

Not really.  You can power the 3007 with a higher supply voltage, but when both are powered at +9v it makes no difference.

2. Is possible to make an inverted phase stero effect to Pearl Chorus?

Yes, but it will be a little complicated.  Also, it will be tricky to have the same kind of mix control.

3. I like Pearl for this!  

So do I.

4. What kind of solution is better?

They both probably sound the same.  I don't know which one has a higher input impedance.  Use a socket for the dual op-amp when you build yours.  Then you can put whatever dual op-amp you want.  The M5218AL is a SIP type chip, but Rohm makes the BA15218 which is a DIP and will fit in the 'normal" 8-pin socket.

[rocker-D82]

2. Is possible to make an inverted phase stero effect to Pearl Chorus?

Yes, but it will be a little complicated.  Also, it will be tricky to have the same kind of mix control.

4. What kind of solution is better?

They both probably sound the same.  I don't know which one has a higher input impedance.  Use a socket for the dual op-amp when you build yours.  Then you can put whatever dual op-amp you want.  The M5218AL is a SIP type chip, but Rohm makes the BA15218 which is a DIP and will fit in the 'normal" 8-pin socket.

2. I can usa a dual gang pot to perform this task. It will take the same amount of mix by the two side (left and right). Can be a good solution?

4. Can I use dual opamp like TL072, 4558 or a better TLC2262?

[Mark Hammer]

2. I can usa a dual gang pot to perform this task. It will take the same amount of mix by the two side (left and right). Can be a good solution?

4. Can I use dual opamp like TL072, 4558 or a better TLC2262?

Sure.  Use whatever op-amp you have available or prefer.

Looking over the CH-1 schematic again, I realized I made a big mistake.  The CH-1 does NOT provide sum and difference stereo chorus.  Instead, it gives you dry+delay if you use only one output jack, and dry separate from delay if you use both jacks.  My apologies for the misunderstanding.

I think this means you only need a single blend pot, not a dual-ganged one.

[Bernardduur]

Personally I once owned a Pearl Chorus; I really liked the sound of the unit because it is not that over the top and not as sterile.

The vibrato mode was my special "gimmick", I really liked it. Then I sold it. It did sound huge on guitar, but very less on bass.

Still I am sorry for myself. My small clone helped me through the time.

[MartyMart]

I have a pearl CH-02 Chorus, its a very fine sounding circuit IMO, the
mix balance and tone controls make it very flexible !
I'd never sell it ..... !

Marty.

[rocker-D82]

There's a component attached through a 220k resistor to the base of Q1. It's called AVR-1. What is it? Is it a trimpot, as I think?

[Mark Hammer]

Yes, that is what it is.  It adjusts the clock rate.

[rocker-D82]

There's a sense to make it as a pot?

[sevenisthenumber]

How is the bypass on the pearl CH-02? Does it suck tone? Can it be made true bypass?

[ppatchmods]

I have a pearl chorus and have owned the ce-2 and they are very comparible, but the pearl is more tweekable and a whole lot more warble.  It is very nice! The newer dano chorus in the small blue case sounds pretty good too!

[sevenisthenumber]

someone said there are a few versions of this pedal? Mine is a red color.