Ring Modulator Chip

[Tony]

Hi,

I was wodnering if anyone can suggest some chips that are good for making ring modulators.

Thanks,
Tony

[ExpAnonColin]

You want 4 quadrant multipliers. There are a lot out there.  The most common is the AD633, particularly because you can use a 9v battery with it (sometimes).  Next up is the 1496.  This one's a bit less common in pedals because it requires more voltage, but it will still work and is sort of common in mod. synths.  Then you have all of the various dual, quad, etc 4 quadrants out there, but the AD633 is your best bet.  People also can pull off ring modulation with OTAs, such as the common CA3080 and LM13700.  The moog ring mod uses a LM13700.

-Colin

[guitarhacknoise]

hello,
analog devices has a 4 quadrant multiplier , ad633.
kind of expensive, like 8 or 9 bucks, but seeing that you don't really need many external parts it is really cheap!
there is a schem around somewhere, try a search using "fatman ring modulator"


or there is the lmc567, search "thing modulator"

or there is the robovox over at munky's place, this one is cool but I have had lots of noisy (bad kind) problems. ie click click click.......

non-of these are really a "ring modulator" but the analog devices chip is probably the closest thing to one,

sorry about the links thing, I'm at work and should'nt be doing this, please don't rat me out!

-matthias
edit:
ask colin, lol!

[guitarhacknoise]

hey, i just remembered that the ad633 needs +/- 12 -15v, so you'll have two projects on yer hands.

[Paul Perry (Frostwave)]

I use an AD633 in my commercial Frostwave "Blue Ringer", it was the best I could find (believe me, i would have used a less expensive and non-AD chip if i could have!!) and +-15v rails, because noise floor is dependant on rails. But I'm fussy with ring modulators, because there is nothing more annoying than carrier bleedthru.
Colin (or anyone else who has checked out the Moog ring modulator) is there a noise gate in it? Because, that is the alternative to get it quiet when not playing (you dont notice bleedthru when wailing away on your axe).
Those OTA based ring mods work, but I think you might need a regulated supply for them as well, because of the way they cancel out the input signal (see the LM13600 or Lm13700 or NE5517 application notes for the 4 quadrant multiplier ckt to see what I mean.)

[niftydog]

Hey Paul, asside from the cost, what do you have against AD? I'm about to buy a crosspoint switch IC from them at $80AUS a piece, I don't want to buy an expensive lemon!

[ExpAnonColin]

I use an AD633 in my commercial Frostwave "Blue Ringer", it was the best I could find (believe me, i would have used a less expensive and non-AD chip if i could have!!) and +-15v rails, because noise floor is dependant on rails. But I'm fussy with ring modulators, because there is nothing more annoying than carrier bleedthru.
Colin (or anyone else who has checked out the Moog ring modulator) is there a noise gate in it? Because, that is the alternative to get it quiet when not playing (you dont notice bleedthru when wailing away on your axe).
Those OTA based ring mods work, but I think you might need a regulated supply for them as well, because of the way they cancel out the input signal (see the LM13600 or Lm13700 or NE5517 application notes for the 4 quadrant multiplier ckt to see what I mean.)

The moog IS an OTA based ring mod.  There's no carrier bleedthrough-and no noise gate, I don't believe.  You can usually null the carrier signal with a trimpot with lug 1 to +V, lug 2 to the carrier or input signal, and lug 3 to ground, I think, depending on the circuit (there's more to it than that).

-Colin

[ExpAnonColin]

BTW, you can easily order AD633 samples.  You can also get them for sorta cheap from futurlec: http://www.futurlec.com/AnalogDevices/AD633JNpr.shtml

-Colin

[Paul Perry (Frostwave)]

Hey Paul, asside from the cost, what do you have against AD?

AD make great components.. but, they have a bad record of letting them go out of production!! look at their record witht SSM chips, they took over the company to get into a particular market (audio compressors & preamps) then dropped various that had become standard. All companies do this (except Maxim, which promises to never drop a chip.. but, they DO go 'temporarily out of stock').

[niftydog]

ahhh. yeah, that sucks. I come up against that all the time. Well, not likely to require too many of these puppies, especially at $80 a pop! Unless ofcourse my project goes fantastically well and people start asking to buy one for themselves!

I am very impressed with Maxim, I've ordered plenty of samples from them, and they have the coolest ideas for chips, and boy, what a humungous range of devices!

[Paul Perry (Frostwave)]

Yeah, Maxim have some good stuff! one of the latest is a latching relay driver, makes it piss easy to get the "two way current". Wahoo! but, do I design something with only one supplier?? and, of course, the pricing is just high enough to make me think, nah, lets use a toggled flip-flop  :roll:

[ricothetroll]

Moog Ring Mod definitely has a noise gate, a pretty good one but when listening carefully you can still hear it. Just gently hit your guitar strings and you'll hear the carrier appear and disappear.

By the way the circuit works internally at +/- 12V -> ICL7662, but maybe it's +/-9V measured 12V because of that's what the Boss PSU gives when slightly loaded. I've seen no regulator excepted a 78L05, for I don't know what purpose.

[DDD]

Properly used CA3080 (or LM3080) as well as LM13600 (13700) can solve the problem with the 9-Volt power supply.

[Cliff Schecht]

I've posted before on how to use the inexpensive LM1496 with a single 9V supply to get a balanced modulator. I wonder if anybody tried it out..

[ricothetroll]

I wonder if anybody tried it out..

I first simulated it on ltspice, but couldn't make it work properly : output signal was distorted, the "bottom" part of it kinda "planed". The solution I found was to create the two Vrefs with opamp buffers : the voltage drop with the resistive voltage divider made the circuit behave strangely. That's more an observation and some tweaking than deep understanding of the Gilbert cells

Then I breadboarded it, adapted for a single 12V supply (i needed 12V anyway for the XR2206 I used for the carrier generation). It worked quite good, but to get rid of the bleed I had to set both signals so low that I could hear the noise floor at the output. Anyway, I still had a little bleed, at twice the frequency of the carrier. As I can't stand noise gates, I finally decided to forget the MC1496

By the way, I had the same problems with LM13700, that appeared to be even noisier that the MC1496. I also, tried the trafo/diode one quite a long time ago, but without being too regarding on noise issues. But as I read here about lots of people having problems to get rid of the carrier bleed with that one too, and that two trafos are not far from the price of a 633....

[Cliff Schecht]

Hmm.. I setup that circuit similar to the one I designed for PAiA, which nulls just fine. You probably need to adjust the inputs so that the signal is less than 25 mV after the dividers, the input transistors saturate past this point. My original design is meant to take 10V P-P synth signals, anything over this will start to clip it. Make sure that you aren't clipping the inputs or you'll never get the signal nulled.

There is a trick to getting the circuit to null too. IIRC you input a signal to just the carrier, leaving the modulator floating, and adjust the carrier null trimmer until the signal nulls completely. Then input a signal to just the modulator and adjust the adjacent trimmer until it nulls completely. Then when you input a signal into both, you should have no bleedthrough. It's been a while since I've done this though so you may have to play around with which trimmer you adjust as you try to null the signal (there are only four possibilities so it's pretty easy to figure out).

[ricothetroll]

The one you designed for PAIA works in +/-12V isn't it ? First time I wired a MC1496 it was following the datasheet instructions, with +12V / -8V. At that time I quite enjoyed that chip because I found out it was very silent, at least a lot more than the LM13700 I tested just before. The headroom reduction that occured from 20V to 12V might have caused the relative rise of bleed.

By the way I tried the "two pots" technique for carrier suppression but without any success, I couldn't get the bleed lower than what I did with one pot. But I didn't operate as you suggested, so my conclusion was maybe kinda premature.

Another thing that annoyed me was the small temperature stability resistor, between pins 8 and 10. As pin 8 is tied to Vref (hi), that makes the carrier input impedance very low, even if you change it from 51R (datasheet schematic) to 1k. For very low frequency signals you have to use HUGE coupling capacitors to cut low enough. I realise my biasing technique made things even worse, making the Vref impedance even lower. To cure that problem, I also tried to DC couple the buffer transistor between the XR2206 and MC1496, but without any success, as the carrier was then saturated whatever its level. I must admit I'm not too sure of the way I did it, I biased the emitter follower to have Ve=Vref (hi).

Anyway, it's nice to have a feedback from someone tat struggled with the same chip, I hope I'll figure out why things didn't work well in my case...

Best regards.

Eric