DH pitch shifter, questions.

[El Heisenberg]

Not much in the forum about this. At least I couldn't find anything.

Anyone build this?

I have questions about the schem. The diodes in the layout aren't in the schem. Around the IC there are switches and button drawings. THere are two momentary switches for robot and vibrato. Wouldn't it be ok to use a normal SPDT for the vibrato or both switches?

There are also two buttons drawn on the schem for pins 17 and 16 of the IC, but aren't used in the layout. What does this do?



How does this circuit work? Whatsit sound like? Or do??? Turn the rotary switch to get a different pitch?


Maybe it's time to learn to etch PCB. Perfing this might be tough cos it ain't drawn into the schem.

[Govmnt_Lacky]

Anyone build this?

I built this..... to make a long story short..... save your time and money!

THere are two momentary switches for robot and vibrato. Wouldn't it be ok to use a normal SPDT for the vibrato or both switches?

The switches HAVE TO BE momentary. The Holtek chip changes modes with the momentary action. A locking SPDT will not work.

There are also two buttons drawn on the schem for pins 17 and 16 of the IC, but aren't used in the layout. What does this do?

These switches allow you to cycle through ALL of the functions of the chip with an UP/DOWN toggle. Kind of like a programmable foot pedal that cycles through pre-programmed settings on an amp. You have to have the dip settings set up correctly to enable this though. Check the datasheet.

How does this circuit work? Whatsit sound like? Or do??? Turn the rotary switch to get a different pitch?

Like I mentioned above.... save you time and money. This chip was designed for use in toys. NOT GUITAR/BASS. I built this and it is still shelved! It works but has many bugs in it and it does not merit the time compard to the result you get from it.

[El Heisenberg]

Well I didn't expect it to sound like a rack mount pitch shifter at all, but is it REALLY that bad? I don't mind weird crazy sounding. But is it hard to get working?


Ugh, I've already bought the chip for it. Nothing else yet tho. Anything else I can use this for? No....it's a toy chip huh? BAH!

[Govmnt_Lacky]

I believe there are some posts on here if you search the threads. After I built mine, I searched for some answers to the problems I was having. I even contacted JD about it. After finding no GOOD posts about the project and going through ALL of JDs ideas... I finally decided to shelf it. Really, it is the ONLY project I still have outstanding that was never really finished. The result was just not worth the effort, time, and especially MONEY 

[wormfooduk]

I have one in a box somewhere too, hoped to get it working one day, but had no luck the first time.

[caress]

check out the death by audio robot - it should give you an idea of what it sounds like.
i think maybe they drive the HT chip with an LM386 or some other gain stage?

[anchovie]

Here an easy circuit for guitar using this chip:

Use a suitable supply voltage (I made 3.8 volts by using a LM317 with 330R from Vout to ADJ and 680R from ADJ to ground) and connect to VDD and TS.

10uF cap from VDD to ground.
10uF cap from VREF to ground.
100nF cap from input to AIN.
10K resistor from AIN to VREF.
47K resistor from OSC1 to OSC2.
Momentary switch between TGU and ground.
AUDIO to the CW lug of a 100K linear pot, AO to the CCW lug (this is the Blend control)
Centre lug of blend to the + of a 10uF cap, - to a 100K log volume control.

This sets up the input opamp as a comparator so you get a full-on square wave fuzz. The momentary switch cycles through the pitch-shift/robot modes. If you have trouble with the sustain, play around with the 10K resistor value.

Tracking is bizarre, in that you'll notice the interval change if you play chromatically up the fretboard. This is what makes it fun, however. It's like adding a tone-deaf guitarist to your jam session.

[Taylor]

The diodes are for a rotary switch to directly select modes. They're to be used instead of the up/down switches, so you can pick which one you want.

[moosapotamus]

I built it up on a breadboard a while back. I t was a lot of fun. I recall it going together pretty easily. I also modified it a bit to make it sound even wackier...

http://moosapotamus.net/IDEAS/DHpitchshifter/DHpitchshifter.html

There is a "normal" sounding clip of it at home-wrecker.

http://home-wrecker.com/salvo.html

~ Charlie

[gigimarga]

I've built it some time ago and I was very disappointed about it...it seems to me to be completly unuseful...and very low sound quality...

[Taylor]

I think the trick is to not expect anything like a Whammy pedal. It's basically a goofy voice changer toy made into a pedal. I think it delivers on that.

[El Heisenberg]

yea it certainlyis goofy....


I gotta do something with the damn IC....besides another distortion

and something that'll warrant a spot on my pedal board

[eniacmike]

http://www.youtube.com/watch?v=7pwyb9jHV3Q

here is my video.. i just played some loops through it to show what it can do.
it is extremely lo-fi and not that great of a sound. I couldn't get the "robot" momentary switch to work, and I think alot of other people had that problem too.

[Taylor]

http://www.youtube.com/watch?v=7pwyb9jHV3Q

here is my video.. i just played some loops through it to show what it can do.
it is extremely lo-fi and not that great of a sound. I couldn't get the "robot" momentary switch to work, and I think alot of other people had that problem too.

Wow, that sold me. I have to build it. I have programmed my own Whammy workalike, so a horrible pitch shifter would be a great addition to a good one. Thanks for the video.

[glops]

I like the video, as well.  Ordered the chip from Mammoth. Thanks!

[Govmnt_Lacky]

so a horrible pitch shifter would be a great addition to a good one.

Very funny....

Honestly though, this circuit really is not worth it in my opinion. You get a lo-fi sound, huge volume drop, constant crackling (as in the video), non-working robot switch, partially working vibrato switch..... Really not worth it!

I like the video, as well.  Ordered the chip from Mammoth. Thanks!

Just looked at Mammoth, they only sell the HT8970 Echo chip. The one you need for the GGG Pitch Shifter is the HT8950.

[El Heisenberg]

Yea, man, looks like you're gunna have a reverb or SHecho project on your hands!

[mph]

I couldn't get the "robot" momentary switch to work, and I think alot of other people had that problem too.

I've got the same problem with this switch. I have checked everything so many times, that I have decided to remove this switch to use it in a better project (I've used expensive Carlings at 6€/p  ).
But the sound could be interesting when combined with a ring modulator or even with a synth, and delay.

[eniacmike]

I couldn't get the "robot" momentary switch to work, and I think alot of other people had that problem too.

I've got the same problem with this switch. I have checked everything so many times, that I have decided to remove this switch to use it in a better project (I've used expensive Carlings at 6€/p  ).
But the sound could be interesting when combined with a ring modulator or even with a synth, and delay.

http://www.radioshack.com/product/index.jsp?productId=2062543

I know this probably doesn't help you if your in europe, but I used these switches from radio shack they are $3 for two switches (one red, one black) they kind of look like old nintendo buttons. But if anybody is building it I would say ditch the robot switch because it doesn't appear to work for anybody.

I think it would be cool to see a new project based on the holtek chip. The DH project is okay but the board could be smaller and to me it sounds like the op amp is getting rail to rail distortion. You really have to adjust your playing style to get it to work for you.

[El Heisenberg]

http://www.youtube.com/watch?v=XwaGMyyKSzo&feature=youtube_gdata_player


Not the same cicuit but cool. Uses the same chip


What i want is to use a big flat pot for the rotary switch so i can switch the interval with my foot after a loop pedal. That way i can switch the key of a loop since i only have 20 seconds available.