Stand-alone true pitch shifting vibrato for guitar

[plexi50]

So close. I will finish it up tommorrow. Visine time /

[sluckey]

Looking good!

[sluckey]

I thought those .47µF caps were very small. You have installed .047µF instead. Try it and see if you like them. If it sounds too thin or bright, put the .47s in there.

[plexi50]

Opps! I was bound to do something like that. Maybe i can use the caps from the old hammond board. I dont have any here except for them. Thanks for catching that!

Ok here are the right caps. They look good too! I have to remember that decimal before the numbers

[plexi50]

Ok i am all wired up and finished minus one wire connection
Steve is the 0.047 cap from the Mixer pot going to another switch?
Vibrato = open?
Chorus = closed?

All i have left is a single wire to connect from the .01 cap to what i believe is a switch

I only see one switch on the front panel of your actual chassis build on the Speed (rate) pot

I fired it up and my voltages are:
A-330 VDC -12AU7
B-326 VDC -12AU7
C-248 VDC-12AU7
D-172 VDC-7247-12DW7
E-312 VDC
Node C from your voltages should be 124-5 vdc / I have not plugged into an amp/guitar just yet

[sluckey]

Ok i am all wired up and finished minus one wire connection
Steve is the 0.047 cap from the Mixer pot going to another switch?
Vibrato = open?
Chorus = closed?

Yes. Look at the revision 1 layout.
http://home.comcast.net/~seluckey/amps/warbler/warbler_rev1.pdf

All i have left is a single wire to connect from the .01 cap to what i believe is a switch

That's the fast/slow range switch for the vibrato rate. It's on the left side of my front panel.

I only see one switch on the front panel of your actual chassis build on the Speed (rate) pot

I didn't use a Vibrato/chorus switch on my build. The cap from my mixer pot goes directly to the board on mine. Remember, you're building from the improved revision 1 schematic. If you don't have room for another switch next to the mixer pot, just wire the cap straight to the board IAW the layout. You don't really need that vibrato/chorus switch but it is a convenient way to mount that .047 cap.

[sluckey]

Also gotta find out why your node c voltage is twice as high as mine. Measure all tube voltages and post.

[plexi50]

Ok Steve. I have the Mixer .047 cap wired straight to the board

All voltages are good except for node C

Checking tube pin voltages now

[plexi50]

I did a voltage check on V1 V2 V3 and all voltages look good with no fluxuations

I am assuming since Nodes A-B-D-E are reading correct on the filter caps that these nodes are proper

I had to turn all the pots to the off CCW position to get a steady reading on V1 V2 V3

BUT!  V4 is all over the place and the voltages are pulsating up and down. Here are those voltages:

V4 VDC
Pin 1=249
Pin 3=14.80
Pin 6=170-195 pulsating up and down
Pin 8=1.380-1.450 pulsating up and down

I did connect to guitar and amp but there was no effects to be heard. Just plain amplifier tone

[sluckey]

OK, I'm home and can do some troubleshooting with you, so if you can, stay online. I have my unit open so we can compare readings. It sounds like yours is 90% functional, but I don't like where we may be headed. Since the voltage is off on the plate of cathode follower V4A (pin 6) I'm suspecting a problem in the cathode circuit. Here's the plan...

Turn the unit off to make some resistance checks.

  1. Check resistance of V4 pin 3 to chassis ground. Put one meter lead directly on the tube pin 3. Should be 1260Ω. If you measure 11K then the primary of the SR is open. Let's hope you forgot the jumper wire from terminal 1 or 7 on the SR. (refer to the layout).

  2. This step depends on your findings in step 1. Cross your fingers!

Just a little extra info... The primary side of the SR should read 260Ω between terminals 1 and 7. It's actually 6 windings in series. There are tiny wires on all terminals 1 thru 7. All it takes is one broken wire to make the SR useless.

Good luck. I'll check back often and if we happen to be online together, I'll stay with you til we know what's wrong. I don't think it will take long.

[plexi50]

Ok Steve i am reading your last post now. I just posted all the preamp voltages:


All preamp tube VDC voltages are as follows:

V1 VDC
Pin 1=145
Pin 3=7.85
Pin 6=131
Pin 7=28.50
Pin 8=45.00

V2 VDC
Pin 1 =130
Pin 2=28.50
Pin 3= 45.00
Pin 6=128
Pin 7=2950
Pin 8=46.00

V3 VDC
Pin 1=68.00
Pin 2=.017
Pin 3=2.275

V4 VDC
Pin 1=249
Pin 3=14.80
Pin 6=170-195 pulsating up and down
Pin 8=1.380-1.450 pulsating up and down

[sluckey]

Stay online and do the resistance check.

[plexi50]

Ok the resistance check shows the SR open and i am reading 10.85K off V4 pin 3 cathode to chassis ground

Checking routed wires from SR transformer to board now

*All wires from SRT are connected to there board points correctly

[sluckey]

OK. Put your ohm meter leads directly on terminals 1 and 7 of the SR. Still reading about 10K? If so, that's bad. Take a flashlight and look closely at all the tiny wires on all the terminals on that side of the SR. Does everything look OK? Pay close attention to the terminals that you have been soldering on.

What you got?

[plexi50]

Yes SRT reads 10.80k across 1&7

Been testing all the transformer wires and found a blck one that is not connected continuity wise

Soldering back on now. It looked solder on but there is a white goo residue from old age

Back in  minute

[plexi50]

Ok got it! One tiny black wire was not soldered good enough

That was the problem with the higher voltage on node C

Node C now 121 VDC. Man this is awesome diagnostics

So i plug the guitar into the input and the other jack Mixer into the amp input?

[sluckey]

Yep. I'll stay online to see if it goes well. Turn the mix control max CW for maximum effect or turn it max CCW for dry signal. Then bring the depth control up and set the rate as desired. Let me know what happens.

[plexi50]

Ok hooking up now /

[plexi50]

Wow! It sounds cool! Real sweet sweep. Rate,Depth & Input pots working good
There is one issue. The mixer pot seems to not do much until it is near full CW position but i understand that better now between a dry and wet signal

[sluckey]

Mixer pot needs to be a linear pot. That would be Alpha type "B". You didn't use an audio taper (type A) pot did you?

[plexi50]

Yep thats what i did. I have to find a Linear pot or order one. I think it sounds real nice. I need some time to play with it and hear it after i replace the mixer pot. Thanks Steve for your help again. Great little vibrato. This was an intense but fun project

[sluckey]

If you have to order one, get a 500K linear.

Enjoy. You're the fastest builder in the West, err, South!   

[Willabe]

plexie50,

        ALL RIGHT!      :toothy2:    now you and your gittar got it made in the shade with the cool soundzzz spinnin round     :toothy12:    and round    :laughing6:

How about some pics of the top side of the chassis? When your done taken your new girl for a drive of course. Under side looks great, you do very nice work.

You guys had me scared for a little while there, glad it worked out after all! That was better than reality TV.     I happened to come on line just when slucky said he just got home.


             Brad        

[plexi50]

500KL it will be. Thanks. Thats why im burned out a little. Between repair work i dont get many breaks to build my own stuff like i used to. This old 1936 Philco was fun to recap. Theres a good market for a tube vibrato. Im wondering how this would compare to the maggie after i change the Mixer pot. The maggie vibrato is just very sweet

Yeah Willabe it was a CRASH course all the way. I say we delete this thread and market the thing.  
I love what i am hearing. It's real and it works! I need to construct some kind of cab for this
I think i have one in the garage that i can modify / Im gona go look

[Willabe]

Theres a good market for a tube vibrato. I say we delete this thread and market the thing.  

Sounds good to me!       YES SAYS I !!!  Let us dream a little, shall we ???......

sluckey can be Pres./CEO,  plexie, you can be VP, and I'd just be glad to be factory floor manager, ie.... I sit at a table and solder/wire'em up!           Have I said that I don't do well in these cold/overcast NW of Chgo. winters???     :sad6:

I'd still like to hear it with a 4th stage, and a separate dry out for using two amps, left/right to realy spread out the sound on stage. Would give it something to work against itself as a referance point, doppler sound --0-- start point, should "fill" a room much better.

Talk to you guys later.


      Brad          

[sluckey]

sluckey can be Pres./CEO

Thanks, but naw thanks. You guys run with it. I got a day job and I ain't gonna mess up a good hobby.   

[Willabe]

sluckey can be Pres./CEO

Thanks, but naw thanks. You guys run with it. I got a day job and I ain't gonna mess up a good hobby.    

I can hear the throngs of gittar players who are looking for "THE WARBLER" sound calling out ......      slucky, slucky, ......        

All kiddin aside, you know I'm just pullin your leg. I think your a good and generous man, wise too, 5000 + posts proves it!     Thanks slucky for sharing this FX build and all that you share with all of us.


             Brad          

[plexi50]

Just think: Some where in a warehouse there is a box of 5000 SRT's and no one knows what they are

[Willabe]

Right on tube builder man, I belive your right !!!      

Hey, we will find them !!! 

      Brad        

[plexi50]

Read this link: I think it is refering to the matching transformer we are using and the principles of it's function
http://www.nshos.com/hammond9.htm

[sluckey]

That's describing the older motor driven vibrato scanner/delay line. If you want the theory of the circuit you are using, read this...

http://home.comcast.net/~seluckey/amps/warbler/Hammond_AO-41_and_AO-47_Vibrato_Units.pdf

[plexi50]

Thanks. It's all good reading

[Dave]

Well, I got one. Its Sunday morning. I have all my chores done, so I may just get started on my box today.
Here is North East Texas, global warming has caused abnormally frigid temperatures, and at this moment there are conditions just shy of whiteout.
The snow has been falling for about an hour and it shows no signs of stopping.
I guess its time to build tube circuits.

Dave

[sluckey]

Dave, if you're gonna use my layout, you may want to download the latest revision 1 file which has 2 minor changes since plexi50 built his. I eliminated the (mostly useless) vib/chorus switch and mounted the .047 cap on the board.

[Dave]

Thank you sir. I will download the updated schematic.
At one point while reading all this, I noticed that you mentioned that the circuit was a little dark.
Have you experimented at all with remedies for that?

Dave

[sluckey]

Adding the mixer control seemed to take care of that.

[Dave]

Cool. Thanks.

Dave

[plexi50]

I had to make a revision of my own. I cut and removed a small amount of the circuit board and relocated the SRT to the chassis itself. It was sticking out of the bottom of the small chassis i used. I didnt want anything to happen to that SRT

Also i think i want to try a 300 ohm resistor in place of the choke and see if i get more shine. The Maggie did not use a choke in it's amplifier circuit and like a few other amps like the Ampeg Gemini II i really liked the crystal clarity (shine) of the resistor vs the choke in those amps

I have a good feeling something great is going to happen in tinkering with this project

[Willabe]

plexi50, Great job!

Find any new sounds, or notice any thing new sound wise you had'nt found/heard before?


          Thanks,    Brad     

[sluckey]

I put a plexi bottom plate on mine just to protect the SR.

[plexi50]

plexi50, Great job!

Find any new sounds, or notice any thing new sound wise you had'nt found/heard before?


          Thanks,    Brad      

Yeah i was playing with it a few hours ago and i noticed a spot that sounded really cool. See i still have 250KA audio pots for the mixer and depth. I will have the 500KL linear pots this week and that should be even better in bringing out a better sweep and funkability! I think this project is the amps meow!

[plexi50]

Dave, if you're gonna use my layout, you may want to download the latest revision 1 file which has 2 minor changes since plexi50 built his. I eliminated the (mostly useless) vib/chorus switch and mounted the .047 cap on the board.

I was thinking of doing the same thing and using the switch on the front for the power on/off
Scratch that comment / I got the fast/slow switch mixed up for a minute
I already have the vibrato/chorus cap straight to the board  

[Dave]

Well, I didn't get around to it. I'm not used to blizzards in this part of the country, and I thought I could just hang out and build this thing today. Instead, I was on the roof of the barn trying to get the snow off so the tin wouldn't buckle under the weight. Who knew?
Saved the barn.
My horses were all encased in ice. They didn't seem to mind much, but my wife was about to lose her mind because the poor horsies were cold.
I thought she was going to bring them in the living room.
Quite a day when all I wanted to do was build a tremolo device.
Maybe I'll get another chance one day soon.

Dave

[Dave]

If nothing else, I had a little time to think about the build and it led me to this.....
I plan on building the Warbler right behind a 6G15 reverb circuit.
It seems to me that doing it after a 6G15 eliminates the need for the input stage that Sluckey added.
Am I right about that?

Also, I've never used a 6G15 in an effects loop before but this is my plan for this unit. So, how well does the 6G15 perform in an effects loop?

Dave

[plexi50]

Steve i have a question. Changed the Mixer pot to 500KL. After getting some time to play with it i notice i have a heavy pumping wooshing  action at amp idle before playing. Does yours do this? I heard your sound clips and your appears to be silent until used. Whatcha think?

[sluckey]

Mine does the pumping thing too if I have the depth control cranked real high. Almost sounds like a helicopter. I just back off the depth until the pumping stops. I can still hear the background amp hiss changing at the vib rate, just like with many tremolo circuits.

See that 2.2meg resistor that connects to the top of the depth control? I chose that resistor value (by experimenting) to allow the vibrator to have a little pumping with the depth turned all the way up. You should have heard it with a 1meg! Way too much! If you increase the value of the 2.2meg, you will decrease the pumping effect, but you will also limit the strength of the vibrato. You can accomplish the same thing by just turning the depth down some. Mine has plenty of depth for my ears without being turned all the way up.

You can probably smooth the pumping some by increasing that .047µF cap connected across the depth pot. And that 10K resistor in the cathode of the driver tube may have an impact on the smoothing of the vibrator. That resistor was factory selected on the original AO-47. I would think that decreasing that resistor would decrease the pumping (and the strength) of the vibrato.

If you experiment with this, post your results, especially if you find an improvement.

[plexi50]

I would like to get a tad more glassy shine but heres what i did today:


I put every else aside this afternoon.  Here is what i did and i really like the change though it was minumal< (Is that spelled right?)

I played with the 2.2Meg resistor and changed it to a 3Meg

This brought the thump down a bit but still plenty of thump to be had if wanted

I think the Depth pot (intensity) works better and allows for a slower transition. JMO

I have a Magnatone customer that uses his M10 Vibrato for vocals only. Another reason i was really interested in this project

I reversed the Mixer outer terminal leads from your layout and now have CCW off and CW gradual mix

The (2) 500K pots made all the difference in the Mix and Depth pots balancing the controls out perfectly

I dont think there is any need for any further improvements other than to put the On switch on the front panel in place of the Fast/Slow switch which is really not needed

Happy results!!!

[sluckey]

The (2) 500K pots made all the difference in the Mix and Depth pots balancing the controls out perfectly

I never meant for you to change the depth pot to 500K. Only meant change the mixer to 500KL. That explains the increased thumping in your vib.

[plexi50]

I will put the 250KL back in this week sometime. I just changed V1A cathode cap to a 2.2uf. It is still plenty full and depth defined just not as dark

Will raising the value of the 150pf caps give me more shine or is it the .47 caps that i need to try different values to brighten up?

[plexi50]

Tried the .047 caps. They sucked. Lacking warmth. .47's back in. Bridged 470k across 500K wiper and outer pot terminals and have 248KL. Close enough and works better. I want to slow the rate down just a hair more. You have created a Vibrato junkie!