Oakley SRE330

[Synthbuilder]

I checked the pot itself and it measures correctly. Also checked the pot connections and they look okay.

How did you check the pot? The best way is to measure the wiper voltage (middle pin of the pot) with respect to 0V (ground) and wiggle the pot. The wiper voltage should go from -15V to +15V as you rotate the pot from one end to the other. If you can't get to the wiper pin directly you can measure pin 3 of U16 instead.

From what you are saying I would suspect the pot first. Sometimes the internal connection from one of the outer pins to the resistive track can break or become intermittent. This damage often occurs in transit when suppliers put the pots in a big bag all together.

Another part that could be faulty is U16.

[Clbraddock]

Ok I think it is the pot. I tested it in the circuit and reading pin 3 of U16 it doesn’t vary much from +15 volts regardless of turning the pot. That would prob explain why the rate stays so high. I’ll swap it out for a different pot and that will prob fix it. Thanks for your help! It’s a great chorus.

[Clbraddock]

Something I’ve noticed is that when the balance pot is set to 50% I lose some volume and bass frequencies. At 0% or 100% there is no volume loss or bass loss. Just curious if this is inherent to the circuit or if it means I have something not working right. I’m guessing it is phase cancellation, but I can’t say for sure.

[Synthbuilder]

I’m guessing it is phase cancellation...

I think so too.

Once you start to modulate the delay times the cancelled frequencies will move and it won't be so apparent.

[Clbraddock]

What does each mode emulate. Or, I guess it’s it’s own thing and not an emulation per se, but what is each mode similar to?

I’m pretty sure 3 phase is organ chorus, and Quad is dimension D, but what about stereo and dual?

Also, it seems like when using multi settings that the depth needs to be set fairly low to emulate classic Juno type sounds. Is that the correct way to go about it?

Thanks!!

[Synthbuilder]

What does each mode emulate. Or, I guess it’s it’s own thing and not an emulation per se, but what is each mode similar to?

Have a read of page 3 of the User Manual if you haven't done so already. There's a few hints there of what each mode does.

But in a nutshell:

Triple phase is Solina, Logan, et al. It is found on some organs, the Lowrey Symphonic Holiday used it, as did some of the early 80s Yamahas.

Quad ensemble mode is in the style of the Roland RS-505, VP-330, and RS-09.

Stereo is modelled after Roland's stereo chorus on the Juno and others.

Dual is unique but essentially is a half way house between stereo and quad.

None of the them are Dimension D/C as this requires cross channel feedback and some unusual EQing. But the stereo mode can sound similar if you keep the LFO slow and shallow.

The Juno chorus uses triangle modulation and is quite subtle. But note that slower speeds of LFOs require more modulation to have same apparent change in frequency.

Tony

[Clbraddock]

Thanks Tony. That is exactly the info I was looking for! Really appreciate it.

[four_corners]

Just finished building my SRE330, and I'm running into an issue with BBD line 3...

First off, all the pots seem to effect the signal, it seems to generally be working, but I'm only getting a square wave on pin5 of the 1st, 2nd, and 4th BBD.

All components have been quadruple checked, so nothing seems incorrectly placed. I swapped both BBD IC's and they worked in other BBD lines, so the chips are okay.

I took some voltage readings that I've shared below.

These three places all seem to match...

3.5V coming into R183, R204, R232, R258 (L/R of the BBD1 and BBD2 entry point)

15.15V at R181, R203, R227, R257

9V at pin5 of U32, U38, U43, U51 and pin1 of U33, U39, U44, U52


Here is where it gets weird...

4.35V pin2 on U32,U38,U51
9V on pin2 of U43

5V pin3 on U32,U38,U51
3.345V on pin3 of U43

4.35V pin6 on U32,U38,U51
OV on pin6 of U43

7V pin7 and pin8 on U32,U38,U51
0V on pin7 and pin8 of U43



3.55V pin7 of U33,U39,U52
8.8V on pin7 of U44

220mV pin5 of U33,U39,U52
9V on pin5 of U44


My guess is something weird happening around Q12 or Q13, but I don't have any other BC549C's to try. There are 1N4148's there as well I could try swapping? The other area I'm not sure about is pin3 of U43 (which comes from R_BBD_IN), which was 3.345V when the rest were at 5V.

Before ordering more BC549C's, I thought I'd ask here first to see if anyone had any ideas.

Thanks!

[LED-man]

From my experience are diodes and this kind of transistors always fine.
(Except you bought on Alibaba)
Let’s wait what Tony answer.

The most important thing is to have the correct panel settings while calibration.

[Synthbuilder]

4.35V pin6 on U32,U38,U51
0V on pin6 of U43

Normally measuring DC voltage on points that should be high frequency AC signals can lead to confusion. This is where a scope will come in handy. However, from these measurements we can see that something is wrong with the behaviour of U44. Look for a solder short around U44 especially between pins 2 and 3.

[four_corners]

4.35V pin6 on U32,U38,U51
0V on pin6 of U43

Normally measuring DC voltage on points that should be high frequency AC signals can lead to confusion. This is where a scope will come in handy. However, from these measurements we can see that something is wrong with the behaviour of U44. Look for a solder short around U44 especially between pins 2 and 3.

Hmm, I checked the schematic and used my multimeter to check for continuity, and the only shorts I could find on the pins of U42, U43, and U44 were pin 6 and 7 on U42 (which is correct according to the schematic). The pins of all 3 IC's showed correct connections to all the surrounding components as well. I'll unscrew the PCB though and actually inspect the board for any other shorts.

I went through and was able to calibrate everything else on the module which is good news, it only seems to be BBD3 issues currently. The only other calibration issue was OFF3, where I wasn't getting any waveform at all on pin 1, but that is understandable knowing the actual BBD line doesnt seem to be producing anything.

[four_corners]

Found the smallest trace scratch! Was directly next to the solder point, so I only noticed it under a loupe. Went ahead and used a resistor lead to go directly between the 2 pads instead of trying to make a big blob of solder to attach to the trace.

Looks like everything is up and running!

Just wanted to throw this out there, but this is a very well laid out circuit/PCB. Every IC facing the same way, very logically placed components, BBD lines perfectly mirror each others placements. I've had WAY more issues on simpler projects with 1/3 as many components.

[Synthbuilder]

Found the smallest trace scratch! Was directly next to the solder point, so I only noticed it under a loupe. Went ahead and used a resistor lead to go directly between the 2 pads instead of trying to make a big blob of solder to attach to the trace.

I'm glad you found the fault. But I am very sorry to hear there was a fault in the board. Can you send me an e-mail please and I'll refund you the price of the board.

Tony