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Oakley SRE330 News
MUFF WIGGLER Forum Index -> Oakley Sound Systems Goto page Previous  1, 2 [all]
Author Oakley SRE330 News
Firechild
I would like to Emulate the ELKA SYNTHEX Chorus 3 setting which mode should I use?
Synthbuilder
Firechild wrote:
I would like to Emulate the ELKA SYNTHEX Chorus 3 setting which mode should I use?

Sadly I haven't played with a Synthex for many years so I'm unsure now of the details. However, from the schematic each voice channel has two separate delay lines with the delay time of each controlled by its own low frequency modulation oscillator, one running faster than the other. There are two identical channels, one for the upper voice and one for the lower voice. The differences between the various chorus modes are changes in the wet/dry mix, the relative mixes between the two delay lines and the modulation frequency for one of the delays.

The SRE330, and the SE330, cannot replicate the Synthex as the second delay line in each of its channels in QUAD mode is controlled by both the triangle wave and sine wave LFOs. You can't just control that second delay line with its own distinct LFO. In the Synthex you have a separate LFO per delay line. The Synthex is a much simpler system but one that cannot be replicated by the more complex SRE330.

This also means that the SRE330 is not able to replicate the ARP Omni as that has three separate delay lines each modulated by its own LFO.

That said, it may be possible to get close to the topology of the Synthex by using the stereo mode of the SE330 (or dual mode of the SRE330). Sum the L & R outputs of the ensemble into mono in your mixing desk and the resulting sound will give you two delay lines controlled by two separate LFOs. You can't change the relative frequency difference between the LFOs - it's fixed at 1.2:1 - but they are free running and different enough to give you a reasonable amount of movement.

Tony
Rex Coil 7
Synthbuilder wrote:
... This also means that the SRE330 is not able to replicate the ARP Omni as that has three separate delay lines each modulated by its own LFO.

Tony
Ho--kay. That bit of news is something I was not aware of. Thanks for the information, Tony. Straight shooter, you.

cool
Synthbuilder
Rex Coil 7 wrote:
Ho--kay. That bit of news is something I was not aware of. Thanks for the information, Tony. Straight shooter, you.

The Omni is pretty unique in many respects. It's not as rich as the other string ensembles although it does sound nice enough. It's actually probably one of the simplest ensemble units - basically its simply three BBD delay lines each modulated by their own free phase LFO with no dry signal added.

It is interesting that ARP decided to use this topology rather than the one used on the Solina (ie. the 3-phase mode on the SRE330).

Tony
Dr Gris
I've contacted LED-man about building one for me. I'm excited w00t

//Magnus
Dr Gris
And it's finally here!!!
Crazy many variants of chorus in this box, love it!!

Thanks Tony!
//Magnus
tioJim
Hello Tony

Think I'm about to embark upon an SRE330 build but I do like a pro solution for an enclosure so ...

Synthbuilder wrote:
I'm looking to get rack cases for this project. These would be pre-drilled and labelled. Might be a bit expensive to ship outside the UK though.


... any developments on this?

Thanks
Jim
Synthbuilder
tioJim wrote:
... any developments on this?

Sadly not. Paul at Krisp1 looked into doing this for me some while ago and couldn't find enough people interested to make it economically viable. I think the SRE330 is perhaps too big and expensive a project for many people.

Tony
tioJim
Synthbuilder wrote:
tioJim wrote:
... any developments on this?

Sadly not. Paul at Krisp1 looked into doing this for me some while ago and couldn't find enough people interested to make it economically viable. I think the SRE330 is perhaps too big and expensive a project for many people.

Tony


No worries, thanks Tony. It is a bit of behemoth! I'll probably need to set aside a few afternoons for this one wink
Pav
Hi , I'm needing to free up a pa20 lump used with my sre330 and I was thinking of changing to a 1 Amp rated a/c wall wart. Before I drill hole for power socket , worth the question.
I'm thinking the current draw stated is close to the ballpark 250ma recommended for such a supply.
Psu docs suggest retrofitting this should not require removing any diodes, but not whether I need to remove a fuse. There is the question of current limiting resistors I expect..?

I wondered if you could have had a header and jumper system on Psu pcb or retrofit a switch so that it was easier to choose either pa20,pa30 etc.
Synthbuilder
Pav wrote:
Psu docs suggest retrofitting this should not require removing any diodes, but not whether I need to remove a fuse. There is the question of current limiting resistors I expect..?

No need to change anything. A single phase power pack should work if the RPSU has been built for centre tapped line lump. The RPSU documentation suggests not to fit the additional diodes and fuses needed for centre tapped operation to save a bit of money. If you've already built it for a PA20 then you can either add the new socket on the back - or, my preference, buy a new plug for your new 1A AC power pack and fit that to the lead. The benefit of the latter is that if the new PSU doesn't work then you can go back to the PA20.

The new 1A power pack should work - but since the RPSU now has to work on a single phase (two wire) input the rectification will only be half wave. That is, the smoothing caps are charged up 50 times a second and not 100. This means that the voltage across the smoothing caps will have a lower average voltage than before. This may cause problems but this will depend on the voltage output of the power pack. Most power packs are a little, er, inaccurately specified. So give it go, but if your SRE330 output hums, or the power pack itself gets too warm and buzzes, then go back to the PA20.

Tony
quarterturn
I just finished my build of the SRE330. I wasn't feeling the linear power supply route, so I tried a TPS5430-based dual-supply module off eBay. For my purposes it works great - I don't hear any intolerable noise in the audio. I bought a +/-12V model, so I had to do the following mods: R1 and R4 replace with 3322 0805 resistors, and R2 and R5 stack a 1003 0805 resistor. This changes the voltage divider so that the TPS5430's put out +/-15.1V, which is great as it gives me a tiny extra for voltage drop over cables and traces. Anyhow I can power the thing off a 19 or 20V laptop adapter, which are all over the place in my home.

I'm having a problem with the level meter which I am troubleshooting. Possibly there is no issue and my iPhone signal gen just does not put out enough voltage to light up "LO" (don't see how 400 mV is going to get past the reverse polarity diodes after the buffers). However I see 22R between the U11 comparator 15V pin 3 and other nearby chips Vcc, and that seems like a lot.
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