Ooops, I missed something.....analogguru - bump!
I will answer you tomorrow morning - too tired now.
Please send me the better quality schematics by mail.
thanks,
analogguru
Ooops, I missed something.....analogguru - bump!
Bajaman, with my old Leslie (three speed) I don't really remember a slowing down effect when off. On a three speed unit it's a very quick off (brake used), not like the effect of going from fast speed to slow. So having true bypass switching and having the effect at unity gain with the bypassed signal would achieve very much the same effect.bajaman wrote: Regarding brake function.
If I used a dpdt switch and connect it so that it breaks the wipers to R104 and R107 of the frequency trim pots would this have the desired effect of gradually slowing both oscillators to a standstill condition?
thanks
bajaman
check out this link:bajaman wrote: Perhaps brake function is the wrong way to describe what I want to achieve, which is a gradual slow down of both rotors to a standstill condition - freewheeling until the spinning gradually stops.
But Leslies's don't do that. They brake quickly on both the 1 and 3 speed versions that have an off ability.pz wrote:bajaman wrote: Perhaps brake function is the wrong way to describe what I want to achieve, which is a gradual slow down of both rotors to a standstill condition - freewheeling until the spinning gradually stops.
It is a little bit on the noisy side - but certainly a lot quiter than a genuine Leslie speaker cabinet .Bajaman, how about the noise performance of this circuit? Is it noisy?
Why? - I do not see any problem with the VCA and the bass section does not require it as the sound tends to be omnidirectional in that section.How about replacing the present VCA with some OTA like 13700? The second ota could be used in the other channel.
I think it's pretty perfect as is (the CX3 Leslie was not half bad). When I build it I might tack that little distortion circuit they have for some grind. Instead of stereo out, I think I'll split the mono out via a crossover @ 800Hz to get a quasi stereo effect high and low (like the original) unless there's a better way of doing it?bajaman wrote:It is a little bit on the noisy side - but certainly a lot quiter than a genuine Leslie speaker cabinet .Bajaman, how about the noise performance of this circuit? Is it noisy?
How about replacing the present VCA with some OTA like 13700? The second ota could be used in the other channel.
What i meant was to use the second ota in the stereo mode, not in the lowpass section. But my problem is, sometimes i like to make things too complicatedWhy? - I do not see any problem with the VCA and the bass section does not require it as the sound tends to be omnidirectional in that section.
I found that only a very small amount of amplitude modulation was neccessary to achieve a realistic high frequency effect. Incidentally I lowered R29 (4M7) to 4k7 to get this section to work properly .
Ok! With al those add-ons i suppose it would grow up to a rack projectI suppose I could totally redesign this effect by including the pre emphasis, de emphasis and compander circuits used by Roland in their Boss DM2 or Ibanez AD90 units, but my initial idea was to build a clone of the original to evaluate it's performance with a guitar - thanks for the helpful comments regarding this design and it's shortcomings.
I see one problem here with 2399. Originally the circuit uses BBDs 3004. They give delay time range from ~2.5ms to 25ms according to datasheet. This range could be widened with some tricks, of course paying the cost of narrower bandwidth in case of longer delay times.I am planning to redesign this in the future - I plan on using the Princeton Technologies PT2399 digital delay chips etc., but too busy with other projects at the present time
Should work, ensure V/2 at the non-inverting input.Okay - now i understand you analogguru - I duplicate the virtual earth mixing resistors R94, R95, and R97 and invert the control voltage from the hf VCO to modulate the duplicate VCA (Q5, Q6) feeding through the duplicate C28 (10uf). Sorry I misunderstood your original post.
Would an inverting op amp with 2 x 10k resistors be suitable for the CV inverter stage?
I didn´t calculate or measure them but the values seem reasonable. Treble is the faster...Looking at the ramp up and down times, am I correct in assuming that the CR time constant for the bass section is 4.8 seconds?
The treble section time constant is 1 second?
Yes one direction is faster, I assume it´s the speed up-timeHow does D3 in series with R47 affect this time constant? Does it make the speed change from fast to slow quicker than from slow to fast?
I assume R46 for down and R47 for up....My prototype seems to slow down too quickly - if i increased R47 or R46 would this give a longer time between slow and fast speed change?
Theoretically it should be possible to the stop condition, but....Anyone got any ideas on how to slow the oscillators down to a stop condition (brake function)
Cheers
bajaman
See above.Analogguru - your assistance again please.
Regarding ramp up and down times for the hf section.
Am I correct in assuming the the time taken to ramp up speed from slow to fast is the time constant of R46 and C17 - 1 second, and the ramp down time constant is the time constant for R46 in parallel with R47 and C17 - 0.24 seconds, or is it the reverse or something completely different?
You can replace Q12 by a stompswitch if you like.Regarding brake function.
If I used a dpdt switch and connect it so that it breaks the wipers to R104 and R107 of the frequency trim pots would this have the desired effect of gradually slowing both oscillators to a standstill condition?
thanks
bajaman
Argghhhhh....I am planning to redesign this in the future - I plan on using the Princeton Technologies PT2399 digital delay chips etc., but too busy with other projects at the present time
bajaman
Stephengiles wrote:If you want a unit with the impact of a standard electric mistress, forget companders and heavy filtering, and just worry about layout and decent clock buffering. If however you want a namby pamby Boss type chorus .................