Behringer 2600 Oscillator "Leakage" - VCF Gain too Low

[jjlonbass]

My Behringer 2600 arrived on Monday a good couple of months before I expected it which makes me happy.
However, on having an hour's play with it on Monday night I found something I didn't like. When listening on headphones I found that the output from the VCF is very low in volume and the tone from the oscillators "leaks" past or through the VCF to a much greater degree than any analogue synth I've encountered before.

I think I've worked out what the problem is by studying the original Arp 2600 service manual - the VCF gain has not been adjusted correctly. The idea is to adjust this gain with the VCF fully open when VCO1 is patched in with its VCF input level full such that the VCF output is at the same level as VCO1 output i.e. the VCF provides unity gain.

I'm not too pleased with this and I haven't decided what to do about it.

I would return the 2600 if I knew I would receive a replacement within a short time - but I wouldn't, I'd have to wait months.
I am capable of making the adjustment myself and that's probably what I'll do - the photos of the 2600 PCB I've seen show legends next to the preset pots - there are a set of 3 for each filter type.

Any thoughts?

John

[Michaelniebuhr]

I held back on my order, because I want them to fix the mistakes they're bound to make on a complex piece of machinery like this.

I ordered the Poly D on the day of the pre-order and finally received it 3 months later. Keyboard had about 10 keys with no support. Held on to it for a week then returned it. Hate the keyboard on the replacement, but it isn't exactly faulty. Just really cheap.

I would hang on to yours for a few weeks and see what other reviewers say.

[DesertVentures]

Did you ever sort this leakage out? I have the same problem. What did you end up doing about it? Many kind regards.

[Arpangel]

I’ve got a Gray Meanie, and I’ve never noticed any of these things, I’ll check later, but it’s never affected anything I’ve done, the level of the filter seems fine, I bought mine about eighteen months ago.

[jjlonbass]

I did sort this out - it was due to user (me) error. I had the VCA initial gain set to a non-zero value such that there was some output at all times.

John

[Arpangel]

I did sort this out - it was due to user (me) error. I had the VCA initial gain set to a non-zero value such that there was some output at all times.

John

Easy to do, to say that the work flow on this synth is "unusual" is a massive understatement!

[Wonks]

The same thing happened when the Korg Odyssey first came out as it had a similar feature. If the gain slider wasn’t at zero, you got a permanent sound and a lot were reported as faulty.

[Arpangel]

The same thing happened when the Korg Odyssey first came out as it had a similar feature. If the gain slider wasn’t at zero, you got a permanent sound and a lot were reported as faulty.

This can be a useful feature, especially if you drone a lot, like me.

[DesertVentures]

John, thanks for the fast and insightful response. I looked into it it immediately based on what you said. Mine has worked perfectly in the past (I am an OG owner as well) and somehow now it seems that the filter outputs the oscillators no matter what. It's like there is no functioning gate off. Takes midi fine, but last note played never cuts off.

It could be an oversight or user error, but I don't think so. I post this in case it helps others, as yours did for me.

Very grateful and thanks again.

I did sort this out - it was due to user (me) error. I had the VCA initial gain set to a non-zero value such that there was some output at all times.

John

[The Elf]

Ooops! 'Initial Gain' possibility already mentioned...

[jjlonbass]

Apparently Joe Zawinul had a similar issue with his ARP 2600 when he first got hold of one. I suppose that means I'm in good company

John