malekko 600B ,

 

 

Ok here’s a big one ! An expensive pedal loved by many . I bought it damaged otherwise I wouldn’t buy such expensive pedal . The price asked for wasn’t that great either. But I had my eyes on this for a long time so I took a shot  . I wanted to sell the pedal first and post the article after , but I’ve all the pain in the world to make this thing go.

It’s really a great sounding delay , a bit pricey for what it is , but nice overall !

the building isn’t what you could expect for a 250euros pedal, not that bad but I don’t know,  jack or power socket PCB mounted could be nice. It’s really “boutique”. The kind of construction that many think “boutique”  is. The inside is a pretty dense PCB . Maybe too dense in my opinion to make a quick repair. But size has a price.

IMG_0198-2

The solid wire isn’t the best idea though. I had terrible pain to get the circuit out , just to change an IC I had to remove everything. And put the circuit back in the box was the same pain.

What happened with that pedal ? Fried IC. The user may have connected a power supply higher than 9V (you just need 0.50V more to blow the max1044 as I discovered later ) or reverse polarity plug. Not a big deal , easy fix . I changed the max1044 and the NE571 which died with it.  It’s odd to see  that Malekko didn’t put anything to protect the max1044 . A zener could be perfect for that task , limiting the incoming voltage to 9V . But no zener , nothing.  Weird ?!

IMG_0200-2

I’m not quite sure , I didn’t trace up the schematic, certainly something really similar to but it seemed that they put a diode in serie to protect the circuit from reverse polarity but didn’t include the max1044 in it. Weird again. I could verify but as  I said the pedal isn’t easy to open.

Building the Shruthi from Mutable Instrument I realised that the LT1054 (rated for 100mA ! ) would be the part that I’ll put instead of MAX1044 . Max1044 is nice but a bit milited in current I think. The current IC in the pedal is the ICL7660 which is more robust.

This DC-DC converter is used to produce a negative voltage for the TL074 . Strange idea , I think producing a higher volatge for the BBD would have been better . Offset isn’t a big concern because we use blocking cap to couple circuits (we’re only interested in AC signal in here) whereas increasing the voltage of the BBD could increase the signal/noise ratio and a bigger headroom.

nothing original here circuit wise, just another Boss DM2 or other analog delay clones but it’s a real good one ! No mojo part or whatsoever , just the good standard  TL074 , NE571 and some BBD chip. By the way, don’t trust the crap on the internet this isn’t old stock bbd they’re the new ones produced by cool audio !

I stay septical for the need of +9/-9V on the TL074 provided by the max1044 (which seem to be a sensible IC , at least if not protected)  .  I’m must say that I don’t understand the need of a negative 9V is such simple circuit , it’s not a booster (and even if it is , you don’t need to have a big 10V p-p signal unless you want to make Neil Young sound) and offset isn’t a problem in here. TL074 and such work perfectly good on simple power supply (some are even designed to work with a simple 5V) .

Anyway, in spite of this, if you don’t plug more than 9V , the sound is really great !  and if you like delays you should try it!

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1 Comment

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One response to “malekko 600B ,

  1. Gordon

    Thanks for bringing the cool audio bbd chips to my attention. I heard a few years ago that someone had started making them again, in fact the place that I found selling them “Banzai Music” had another brand of new bbd’s as well as NOS of the original Panasonic ones. They have a few good chips for electronic music circuits and are not too expensive.

    Gordon.

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