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Jürgen Haible Krautrock phaser BUILD THREAD
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2, 3, 4, 5, 6, 7, 8, 9  Next [all]
Author Jürgen Haible Krautrock phaser BUILD THREAD
LektroiD
jhulk wrote:
it states you only need 2 smd caps if using the lm741 opamps but if you are going to use better or newer types opamps then you will need to add the smd caps if it oscillates

which means trial and error on the part of the person who is trying different opamps

i am using the CA3140E which is a direct replacement

i have also fitted a 3 way switch so that i can switch from 2 - 4 6 pole operation and added the res pot

still to design the front panel yet though thinking a hammond case off board pots and switch as a stand alone unit


If you want the faithful Schulte sound, stick with the 741's… Sticking in audiophile chips will sound further from the original. Check the "What I keep" section on Jürgen's page.
fragletrollet
So I`m hoping that polarity/orientation on the bulb-sockets don`t matter? lol
LektroiD
fragletrollet wrote:
So I`m hoping that polarity/orientation on the bulb-sockets don`t matter? lol


Technically it doesn't matter, as each terminal feeds either side of the filament (it's not polarised like an LED).
fragletrollet
Right-e-oh! My build is about finished on pcb then Guinness ftw! Now I gotta do something smart about keeping it dark in my non-enclosed rack (making it MOTM style). Wonder what could cover the bulbs/LDR`s without pushing the "top" ldr`s too close to the bulb when the whole thing is mounted 90 degrees.
fragletrollet
Why is there a star next to the 2k4 resistors?
LektroiD
fragletrollet wrote:
Why is there a star next to the 2k4 resistors?


They can be increased up to 5K1 for higher output gain, but it can increase feedback as a side effect. Check on DSL-man's build page.

Quote:
Loudness:
Coming back to the phaser and playing with it in a new track, I came to realize that its out volume is low compared to the signal volume coming in.

That is not necessary a problem, however raising the input volume does not raise the out volume, rather it gets the module into distortion wit ha constant volume out.

As it is a little too low for my taste, wanted to raise the out volume using the last op amp.

Is the resistor to tweak R57? what would be a good value to change it to?

No. Increase R54 and R58 instead.

JH.
R54/R58 = 2K4 in BOM

I tried the output volume mod as well as the feedbackpath mod and found both mods pretty useful.
R54 and R58 are 5.1K now, which feels closer to unity gain for me, but it is probably easier to overload the phaser with high feedback. (tick)approved by DSL-man, but try 4k7 too
sanders
I bought one of these PCBs, indicator lamp, lamp socket, etc from Juergen before he passed away. I still haven't built it-- but will definitely get to it eventually.

I'd really love to have a copy of the Schulte Compact enclosure made. Wouldn't this be great? I know there are stomp box dudes who make custom enclosures and sell them on ebay (like those wedge fuzz boxes and so on). I bet with an order of 10 or so, someone could reproduce this design for a reasonable amount of money.




woodster
Whilst I'm not even building a Krautrock Phaser I still watch this sort of thread, as they always come up with questions and then the answers follow...

I just wanted to thank Magman for his contributions, as they appeared not have been acknowledged and his input seems to be full of insight.
LektroiD
magman wrote:
For the stages, you can either put jumpers on the board and use shorting links to select the number of stages or you can wire to a DPDT ON-ON-ON type switch for an off board stage selection.

Regards

Magman


Hi, I'm looking at the DPDT ON-ON-ON type switch option, but seems I'll only get two positions out of it (the centre position is used for the ground and the outer positions for the selectors), it would need an extra pin for a third position. How can I wire it so I can use all 3 positions?
LED-man
The usage of a rotary switch solve your request.
fragletrollet
An example of the above mentioned switch would be appreciated.

Can I use bc560b instead of bc560c? And bc550b instead of bc550c?
LektroiD
LED-man wrote:
The usage of a rotary switch solve your request.


I did think of this, but I prefer the toggle switch. If it's absolutely not possible to wire a toggle, then I'll have to go for a rotary as a last resort. I'd rather find out if the toggle is possible first though.

fragletrollet wrote:
An example of the above mentioned switch would be appreciated.

Can I use bc560b instead of bc560c? And bc550b instead of bc550c?


I'd guess they could work, as long as you use 'b' types for both pnp and npn, but I would socket them to make sure. Other than that I could send you one of each if postage is reasonable enough. PM me your address and I'll find out.
magman
Hi folks,

Sorry for the confusion, but the switch I was referring to was like this one from ESR (towards the bottom of this page).

These switches are also sometimes called DP3T and I think they are available form places like Farnell, Mouser and eBay.

Here's a link to show how to wire them up.

http://www.youtube.com/watch?v=14i2B8scNaI

On the transistor front, don't assume that a BC560B will replace a BC560C. The last letter denotes the gain range for the transistor, with the C type having a much higher gain. The real test will likely be to just try it and see, but I don't think that Jürgen would have specified a C type without good reason.

Regards

Magman
fragletrollet
I found some C(TA)`s in my inventory w00t
muckmires
I rcv'd my board and "extra" parts from Thonk today, and opened the Mouser order that used fragletrollets project list,and it's almost complete. The onboard power components are not there, so this is assuming you will use +/-15V power supply. There are some resistors missing, (common ones) and one is the wrong value, but it saved ME the work of having to do all the lookup on Mouser! No complaints. I will add them to my next order. Ready to go!
LektroiD
Mine's built, and working(ish)…

Things that work:
Incandescent lamps
LED
Stage switch
Feedback
Resonance
Modulation dial seems to do something weird to the sound, but can't work out what (presuming phase position?).
Phasing Amplitude adjusts LFO amount.

Things that do nothing:
Low Limit trim

Things that appear wrong:
LFO rate too fast; minimum 1Hz (to my ear).

*edit* Replaced faulty resonance pot, so that now works…

*edit 2* added manual switch (works ok)

*edit 3* fixed stuck LFO problem, now able to vary the speed, but can't slow it any lower than 1Hz (to my ear)... Sounds way to fast to be useable.

*edit 4* tried higher value capacitor to replace the 1µF currently in, now have a 2µ2 in, and the LFO is going about half the speed. Still too fast, but haven't got any larger value film capacitors available. I reckon a 4µ7 or 5µ6 would do the trick, should get about 4 second LFO then, but a film cap of that value would be physically HUGE!

*edit 5* put a 4µ7 electrolytic in to bring the LFO speed down (I don't have any film caps that big), now getting a 5 second cycle. Still a little on the fast side for my liking, hoping for about 8 second cycle. However, now the period pot does nothing to the speed until it gets round to 3 O'Clock, then it suddenly goes fast. Like it's the wrong taper (I used audio/log taper as per the BOM).

*edit 5a* I had the jumper in the wrong position, now set for Audio/log taper, not antilog.

Seems this is the best I'll get it, but confused as to why I need to put in a 4µ7 electrolytic in place of the 1µ timing cap to get a reasonable length sweep. Wondering if its anything to do with the variant of 1458 I'm using (MC1458P).

Also, is there a way to make the source sound inaudible, so all you hear is the effect? I don't need the 50/50 wet/dry mix always.
LektroiD
Well I've been through the whole thread on electro-music, but nothing regarding my high speed LFO. It also freezes at slower speeds after being in manual mode, picks back up when I increase the rate but freezes again when I slow it. I have to cycle the power to reset it), this may be to do with having a temporary electrolytic in.

I have ordered a 4µ7 film cap to replace the electrolytic that's in there at the moment, hopefully that will remedy it, but even with such a large timing cap in, I'm still not getting the long sweeps I'm hearing in some of the demos. Something must be wrong in the LFO circuitry somewhere…

Unfortunately the only person with enough knowledge to answer this is no longer with us. :(
LektroiD
I think I may have found the fault. I'll find out in the next couple of days when I receive the replacement component.

I went through the LFO section with my multitester. It appears the 110Ω resistor was in fact a 1K (they read 110Ω one way and 1K the other)… Seems the company sent me the wrong value… Could be an expensive mistake, and from now on, any components that read a different value either way will be tested before going into my cabinets.

I have resoldered the 1µF film cap, hopefully this fixes the problem. I'll post back when the new batch of 110Ω resistors arrive
slo
Lektroid, can you post the part# of the case you housed the KR in as seen in your YouTube video

Thanxs
muckmires
I ended up building a "standalone" and using the on-board power supply. Upon firing it up, I get the -15 volts, but don't have the +15. My first round of troubleshooting led me to replace the LM317 regulator, now I get +2 volts.
It shouldn't be this hard!
magman
muckmires wrote:
I ended up building a "standalone" and using the on-board power supply. Upon firing it up, I get the -15 volts, but don't have the +15. My first round of troubleshooting led me to replace the LM317 regulator, now I get +2 volts.
It shouldn't be this hard!

Just to check, are you using a transformer or an external PSU (Lin-lump, wallwart, etc.)?

If it's a wallwart, then don't forget that the standalone version needs an AC supply and most wallwarts are DC. You can get AC wallwarts though, but it's worth checking.

If you have got an AC wallwart, check the 4 diodes set up as a bridge rectifier to make sure they are installed in the right directions.

Hope this helps.

Magman
muckmires
Yep, I'm using an external wall wart, 18v AC. I've checked the diodes, all in correctly. I find it hard to believe that it would be the 470u capacitor. And just to see if it's something "out" in the circuit, I pulled all the chips and it still stayed at 2v. Went through with a magnifying glass and checked my soldering, now I've been double checking component values & wearing my eyes out.
LektroiD
slo wrote:
Lektroid, can you post the part# of the case you housed the KR in as seen in your YouTube video

Thanxs


Hi, I just got your PM, which bought my attention to your post (sorry I didn't see it before).

It certainly is a Hammond, I can't remember the model number, I'd have to go through my email receipts to find it, I also bought one for my vocoder build at the same time. I basically measured the PCB and allowed enough room to fit that and have room for the Torroidal. If I can find the part number, I'll post back here or drop you a PM.
LektroiD
muckmires wrote:
Yep, I'm using an external wall wart, 18v AC. I've checked the diodes, all in correctly. I find it hard to believe that it would be the 470u capacitor. And just to see if it's something "out" in the circuit, I pulled all the chips and it still stayed at 2v. Went through with a magnifying glass and checked my soldering, now I've been double checking component values & wearing my eyes out.


It requires 2x18V sources, I used a torroidal to provide this. I'm presuming you are running it with 2x warts?

I'll have a look through my orders and post the part number for the Torroidal, and also the cabinet mentioned in the above post...
muckmires
Yes, and I find out now, one of them is kind of unreliable. I agree that a torroidal might be the way to go. Where did you source yours?
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