Is your tremolo too weak?

[sluckey]

Simply replace the cathode resistor/capacitor for the oscillator tube with a LED. That's all! I did and my tremolo signal voltage increased significantly with the lower frequency benefiting the most. Here are my numbers...

    Cathode R/C... 5Hz = 65V_pp    Cathode LED... 5Hz = 178V_pp

    Cathode R/C... 8Hz = 166V_pp    Cathode LED... 8Hz = 226V_pp

And you have a visual indicator that can be mounted on the control panel too! I put this mod in a simple cathode biased 6V6 PP amp that used bias modulated trem and the trem strength is now way more than I'll ever need. Should work just fine in a fixed bias amp too.Here's my schematic...

    http://home.comcast.net/~seluckey/amps/RCA/Ampeg_J12B.pdf

This is not my idea. You can read about it on Valve Wizard's site...   http://www.valvewizard.co.uk/trem1.html

I had seen this mod before but always thought it was just about a visual indicator. I had overlooked Merlin's statement "By replacing the cathode resistor with an LED we eliminate the need for the large bypass capacitor, and obtain maximum gain and minimum output impedance at all frequencies in one fell swoop."

I believe this mod is for you if you've been dissatisfied with having to compromise between hot bias guitar sound and strong tremolo on a bias modulated trem amp such as a Princeton Reverb or Hoffman's AB763.

[kagliostro]

 

Franco

[Willabe]

I had seen this mod before but always thought it was just about a visual indicator. I had overlooked Merlin's statement...

I missed that too.      Thanks for pointing that out Sluckey.


                Brad     

[punkykatt]

Great timing sluckey, I just pulled out my 68 Princeton Reverb last night and the trem seemed too weak for my liking and was gonna do some tweaking this weekend. Got to try the LED trick. thanks for sharing.  Punky

[plexi50]

Very cool! Im pulling my Princeton reverb apart this weekend and try this. 

[Tom_Hull]

hi

 Steve .

thanks ..

if you missed it gentleman and all

also in the other stuff ,,,,,using  leds  at the  bottom of the page tone difference ?

http://www.valvewizard.co.uk/OtherStuff.html

[Willabe]

Sluckey, Merlin wrote he used a red LED and got ~1.6dcv for K bias. You used a yellow, what is the K bias sitting at on your amp now?

I'm thinking that I will put an LED in the Warbler on the front panel. Should be helpfull and look cool?


             Brad      

[sluckey]

You used a yellow, what is the K bias sitting at on your amp now?

1.8Vdc. I could not tell any difference between the red, green, or yellow. I chose the yellow because it looked the best. It's visible thru the dial glass on the old radio cab, upper right hand corner...

[phsyconoodler]

LED's also can be used in place of the roach bulb in optocoupler trems on blackface /fender amps.

 They smooth out some of the choppiness of the circuit.

[Willabe]

1.8Vdc. I could not tell any difference between the red, green, or yellow. I chose the yellow because it looked the best. It's visible thru the dial glass on the old radio cab, upper right hand corner...

Ok, thanks Sluckey.

LED's also can be used in place of the roach bulb in optocoupler trems on blackface /fender amps.
They smooth out some of the choppiness of the circuit.

I'll have to try that.


            Brad     

[sluckey]

I'm thinking that I will put an LED in the Warbler on the front panel. Should be helpfull and look cool?

I put one in mine today. Looks cool but no performance enhancement. But then the warbler circuit already has more LFO drive than it needs. Absolutely not needed but still cool, in a nerdy kind of way. 

[Willabe]

No, not nerdy at all. Really very cool.

Ummm, is using the word cool nerdy now a days?


            Brad     

[Platefire]

My Peavey Pacer conversion to a DR AB763 with bias tremolo---the speed works OK but the intensity could be a little stronger. I have to turn the intensity up almost all the way to get it to sound like I want it. Platefire

[sluckey]

Do the LED

[Platefire]

I've looked at your schematic and mine and still not sure where the LED goes? V5a don't have a bypass cap on my amp? Just a 4.7K resistor. Schematic is attached. Platefire

[HotBluePlates]

I've looked at your schematic and mine and still not sure where the LED goes? V5a don't have a bypass cap on my amp? Just a 4.7K resistor.

Remove the 4.7k resistor, and put the LED in its place. The LED leg next to the flat spot on the case will go to ground.

[sluckey]

My Peavey Pacer conversion to a DR AB763 with bias tremolo---the speed works OK but the intensity could be a little stronger.

V5a don't have a bypass cap on my amp? Just a 4.7K resistor.

You may get enough tremolo just by putting the missing cap across the resistor. It makes a lot of difference, not as much so as the LED though. Did you follow Hoffman's layout? If so, that cap is missing from his old and newer layouts.

[sluckey]

So, did anyone try the LED this weekend?

[Tom_Hull]

hi

well no but,,,,,
i bought some and they are in the mail..

i find the amp working well as is ..
i would like to see the difference.anyway.and test the voltages ..


tom

[punkykatt]

So, did anyone try the LED this weekend?

I wanted to, but it wasn`t in the cards.  Perhaps tomorrow? So much stuff happens all at once. scheeeeese

[punkykatt]

Sluckey,  I put a red LED in place of the 25uF cap and 3.3K resistor on my 68 Princeton Reverb. Works GREAT!!! Thanks again for sharing that info.

Punky

[sluckey]

Punky, did your trem get noticably stronger?

[punkykatt]

did your trem get noticably stronger?

Yes, The intensity seems deeper and more pronounced.
 
Punky

[worth]

Try the LED with this diode on the intensity pot... INTENSE !!

[sluckey]

That's another good idea.

[jim]

I don't think anyone asked, but in using this mod, will I be able to bias output tubes hotter and not affect the strength of my bias-vary tremelo? I noticed that the BF Princeton trem is particularly tepid if the tubes are biased hot.   Jim

[sluckey]

yes

[Tom_Hull]

Try the LED with this diode on the intensity pot... INTENSE !!

hi worth
for m 12 ampeg 6v6
yes that diode works .i have a .1 cap then 470k ohm resistor then a 1million ohm pot ...

used it on the pot .works  

also the intensitity pot,,, only works at the high end
i  added a 120k ohm resistor to the pot from the wiper to the b= side . now the pot works better .
 
now the speed,,, well .
i worked on this for a day . ,,,,,,,,its the 1k resistor ,, with the 25uf cap........i change it to 3.3k ohm with a 25uf cap.  
Starts up fast enough now ..with no foot switch on my amp or added circuit.

i like the tremolo now .
oh i added a 1million ohm resistor to the tone pots, wiper to the amp.... so the pots  seem to do something .

 , i am still waiting for the assorted LED's,, that are in the mail. . That means i need to shovel snow around  my mailbox .there was a        snowstorm here ,as well.

sounds ok for now ,

thanks worth

[Tom_Hull]

hi Steve .

the leds came in yesterday.

i am back to the original curcuit. almost  ,,,,,for ampeg m12 .
i put the red led in and the curcuit worked less well .
so now i put another two more red ones and the circuit works works well.replacing the cap and resistor
thats 3 red leds in parrell....


the  thumping has gone away as i added another led.. one at a time at 3 the thumping is gone ..

.at four leds in parrell,,,, this  circuit does not work ..

i also had to add a resistor to the speed pot  from the wiper to keep the light blinking for even on slow .
 and the diode on the intencity pot ,,,,started making noise so i took that out . no diode .

big swing and speed fast . i still need to play the guitar through it for a while .to check it all out now ..



here is the assorted leds from..http://www.eled.com/default.asp

[HotBluePlates]

...

the  thumping has gone away as i added another led.. one at a time at 3 the thumping is gone ..

...

here is the assorted leds from..http://www.eled.com/default.asp

You should see from that site there are a lot of different specs for LEDs. You might not have had the right voltage or current rating for the ones you tried. It's not so much about the color, but what voltage drop is created for a given current.

[Tom_Hull]

...

the  thumping has gone away as i added another led.. one at a time at 3 the thumping is gone ..

...

here is the assorted leds from..http://www.eled.com/default.asp

You should see from that site there are a lot of different specs for LEDs. You might not have had the right voltage or current rating for the ones you tried. It's not so much about the color, but what voltage drop is created for a given current.

Hi HotBluePlates

ok so there should only be one led ..its a m12 ampeg

so i worked on it ..the thumping is gone , why ??????

it seems that after the amp warms up i have problems again with all the leds

now i have added a .012 cap in parrell with c5 on steves schematic and but i had to add  a resistor to the speed pot .so that the tremolo would not stop.        


now i have 1 LED and its seems to work better now .

thanks HotBluePlates.

i need to play the guitar and see how it works .maybe it will work as i would like it .maybe not


tom

[tubeswell]

No, not nerdy at all. Really very cool.

Ummm, is using the word cool nerdy now a days?


            Brad     

Kewl is nerdier. (That's how the ozzies say it anyway, so they must be real nerds)

[Willabe]

Ok, Kewl.   

[SleepLess]

Beautiful! Thanks for sharing this Sluckey!