MUFF WIGGLER Forum Index
 FAQ & Terms of UseFAQ & Terms Of Use   Wiggler RadioMW Radio   Muff Wiggler TwitterTwitter   Support the site @ PatreonPatreon 
 SearchSearch   RegisterSign up   Log inLog in 
WIGGLING 'LITE' IN GUEST MODE

The New Buchla Music Easel
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge Goto page Previous  1, 2, 3 ... 43, 44, 45 [all]
Author The New Buchla Music Easel
Umcorps
I think I've posted this before but its a long thread so here is a repost of the calibration routine I was given by BEMI

"On the front of the Easel faceplate there will be 2 fine tune knobs and 2 trim pots.

Make sure all of these are set to %50 percent.

With all the front panel sliders set to bottom position, connect the 218 ‘main’ output into the 208 ‘pitch’ input.

With the 208 taken out of its case there will be 4 trim pots on the back side of the mother-board.

Printed on the circuit board next to these trim pots you will see ‘C-Range’ ‘C-Offset’ ‘M-Range’ and ‘M-Offset’ respectively.

C refers to the complex oscillator
M refers to the modulation oscillator

To begin, make sure these trim pots are centered to %50.

To begin calibration of the complex oscillator raise level 1 on the front panel, turn the timbre knob fully clockwise and set it to a square wave.
Setting the 218 keyboard to octave mode, in the first octave, press key #1 (the key of C).
Slowly adjust the ‘C-offset’ trim pot on the back of the motherboard until your tuner reads C1 (32.7hrz) Then press key #13, adjust the trim pot on the front of the 208 until it reaches C2.

(sometimes this will not be immediately within range due to the nature of analog, if this happens, adjust the ‘C-Range’ trimpot on the back of the motherboard to get it closer to C2, and repeat the steps above once more)

Using the steps above, once C1 and C2 are tuned, you will notice that the 218 will have the notes tuned between C1 and C2. Once this is achieved, press C3 (key #25).

Slowly adjust the front panel trim pot until it is within range of C3. Repeat this step all the way up the octaves until the 208 is tuned to your liking.

These steps are exactly the same for the Modulation oscillator.

On cards 6 and 7 there are 2 different trim pots called ‘C HI Freq Linearity’ and ‘M HI Freq Linearity’. These can be adjusted to your liking for stabilizing the pitch of both oscillators.

Because the higher notes will not be in the ‘perfect’ tune range, each oscillator will most likely need to be tuned to the offset of each other.
"


I think the example tunings given are the default, higher ones but you can use the same process to drop it an octave or whatever. Its tuned high by default to work better with midi if you want to go that route.
Zeitdehner
Yes, you can trim all sorts of parameters of the 208, but it's not very handy to do because the cables that attach the board to the power distribution board are relatively short.
Best way would be to take the 208 out of its case and power it from a "test bench" power supply while having all trimmers nicely accessible and the front panel protected from any damage, but that's "luxury" for lots of us...
So, yes you can trim the range of both oscillators individually, as can you trim the range of the Timbre circuit, the oscillator wave forms, the Pulser duration, Env times, even voltage range of the sequencer...
Before you do so, please make sure you mark the original setting on the trimmers you want to adjust, so that you can easily revert to "factory settings" when necessary.
A nice and convenient way to "tune", to personalise your Easel, to make it even more different...

The only thing to do to modify the Decay caracteristics of the LPG's, to my knowledge, would be to swap out the vactrols... more of a "specialist" thing to do...

nanners
Duplan
Thank you Zeitdehner and Umcorps. Very useful answers ! we're not worthy
papz
There can be huge differences in response between 2 vactrols of the same type and batch indeed.
This is very significant a.o. for the MO timbre, I tested many ones in my 208r rev2 to select the more appropriate, but I have no experience with the LPG.
Duplan
papz wrote:
There can be huge differences in response between 2 vactrols of the same type and batch indeed.
This is very significant a.o. for the MO timbre, I tested many ones in my 208r rev2 to select the more appropriate, but I have no experience with the LPG.


If it's a vactrol thing I won't try to change anything. Thanks a lot !



Last question, when it comes to midi, does the firmware have to be updated (my Easel is from 2014) and would do you do that ?


Guinness ftw!
ttown23
papz wrote:
There can be huge differences in response between 2 vactrols of the same type and batch indeed.


This is true, and valid for ANY circuit that uses vactrols; including many Buchla clones, such as the 291 and 292. Since vactec products (including the entire line of vactrols) are being discontinued, the prices on these make it cost prohibitive to 'match' them.
CliffordMilk
I stuck a couple of real UA726s in my BEMI Easel and am very happy with the results. The only thing I need to sort out is I would like to get more range on the CO trimmer. It’s a little further out than the MO on the higher frequencies. I am assuming a resistor change would remedy this but does anyone have any suggestions as to which this would be?
@green
CliffordMilk wrote:
I stuck a couple of real UA726s in my BEMI Easel and am very happy with the results.


Just curious what one would be going after specifically in doing this? What’s the goal or result you are hoping to achieve? I have it/them in mine and have seen it posted that those that have them are lucky. Why?
CliffordMilk
With the UA726s installed, the Easel warms up in around 2 mins as opposed to 30 and the pitch is very stable indeed. I can tune it, power down and it’s still in tune the next time I turn it on. The next best solution, the one employed on the new Easels is to have a tempco closeish to the UA726 replacement boards. I didn’t try this but I’d be surprised if it was quite as effective.

I now just want the CO range to be the same as the MO. It’s very close but not quite there.
@green
CliffordMilk wrote:
With the UA726s installed, the Easel warms up in around 2 mins as opposed to 30 and the pitch is very stable indeed. I can tune it, power down and it’s still in tune the next time I turn it on. The next best solution, the one employed on the new Easels is to have a tempco closeish to the UA726 replacement boards. I didn’t try this but I’d be surprised if it was quite as effective.

I now just want the CO range to be the same as the MO. It’s very close but not quite there.


Ok I get it. Yes I believe I am lucky then. I will not take it for granted.
01235813
CliffordMilk wrote:
With the UA726s installed, the Easel warms up in around 2 mins as opposed to 30 and the pitch is very stable indeed. I can tune it, power down and it’s still in tune the next time I turn it on. The next best solution, the one employed on the new Easels is to have a tempco closeish to the UA726 replacement boards. I didn’t try this but I’d be surprised if it was quite as effective.

I now just want the CO range to be the same as the MO. It’s very close but not quite there.


For what it's worth, got a new BUSA easel a few months ago and tuning is spot on. It takes about 5 minutes to warm up and with minor adjustment stays tuned across sessions.
CliffordMilk
I’m very glad to hear it but my question was concerned with how to adapt one that had been modified.[/quote]
01235813
CliffordMilk wrote:
I’m very glad to hear it but my question was concerned with how to adapt one that had been modified.


My statment was not intended to answer your question. (Which I didn't quote.)

It was intended to share my current experience in light of what you said here:

CliffordMilk wrote:
The next best solution, the one employed on the new Easels is to have a tempco closeish to the UA726 replacement boards. I didn’t try this but I’d be surprised if it was quite as effective.


Being as this is a "New Easel Thread", and tuning was being addressed, I thought I would share my experience with what is currently a "new Easel". I know I would have been interested in current status on tuning when I was about to buy one. I'm sure I would checked by here.
CliffordMilk
Sorry if I sounded dismissive. I certainly didn’t mean to. It’s great that the new generations of Easels now track our if the box with improved high frequency linearity. If you ever take the 208 out of the case, I’d be very interested to see a photo of the CO card.
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge Goto page Previous  1, 2, 3 ... 43, 44, 45 [all]
Page 45 of 45
Powered by phpBB © phpBB Group