Carolina HummingBird OD

[tubenit]

Since I already had two D-style amps (sorta kinda), I converted the Carolina SongBird Plus into a HummingBird OD.

It has a sorta kinda quasi Marshally front end into a kinda sorta quasi D-style OD section.

It has MORE headroom than the CSBPlus.

I had a 12AY7 in V1 and a 12AV7 in V2 using a 6K6 tube in the first soundbit and a 6V6 in the second one.

You can find the SCH schematic and layout here:  http://www.el34world.com/Forum/index.php?board=17.0

Here are a couple of soundbits showing the headroom that the amp has. It can get nice OD too with sweet harmonics. (excuse the glitch in the recording mix down on the first one)

http://www.soundclick.com/player/single_player.cfm?songid=11015773&q=hi&newref=1

http://www.soundclick.com/player/single_player.cfm?songid=11015326&q=hi&newref=1

With respect, Tubenit

[TIMBO]

Tubenit,it looks like you have nailed it again.Looking at the schem and listening to the sound clips(great as always) it seems that you are confident that the mosfet is wired properly and works well in this circuit  Thanks

[tubenit]

I thought I'd do one more soundclip of this amp showing the contrast between the clean headroom and the OD.
There is delay pedal.  Some slight delay and EQ in the mix.  No other pedals.

It had a 5751 in V1.  12AY7 in V2  &  a 6K6.

I did fingerpicking on the background chording.  I am using mild to moderate lead for the OD.

The only differences between the clean/headroom and the OD is that the clean/headroom dials have the volume and OD drive on "5" and the OD has the volume and OD drive both on  "6.5" & that I picked a little harder in playing when doing the OD.   The amp is pretty touch sensitive and cleans up nicely when picked more lightly.

http://www.soundclick.com/player/single_player.cfm?songid=11034783&q=hi&newref=1

What do you think?  Does this do a reasonably decent job in showing the contrast.

With respect, Tubenit

[John]

Good stuff!

[jojokeo]

Sounds good tubenit. I don't seem to see where the NFB gets inserted back into your circuit?
Are you using a reverb pedal instead of a delay pedal w/in your send/return loop of the amp or after the recordings were made? Lastly, are you using the red, white, and blues 12" or the 10 ragin cajun on your recordings?

[tubenit]

Jojokeo,

Ooops!  There is no NFB, that's an error. I tried it and then removed it. Forgot to erase the NFB by the speaker wire.

I am using a Emminence Cannabis Rex for all the soundclips with the SE amps.

I use a Boss digital delay in the passive FX loop set somewhat slight. And then add a little delay in the mix. No reverb.

with respect, Tubenit

[tubenit]

Sluckey has always given me great ideas and resolutions to my amp "problems". Well, he made another suggestion that has been really successful to me & I have never tried before.

One thread where we (all) had talked about smoothing caps, Sluckey suggested adding a cap from the grid pin to the cathode pin.

So I thought I'd try this on my Carolina HummingBird OD. It works!!!  (I initially tried a 22p from plate to cathode and the amp squealed like crazy.)

Next I tried Sluckey's suggestion and I could NOT hear any difference at all in losing any high frequencies. However, when I tried a 47p, I could clearly hear a loss of highs.

It did smooth out the highs and upper mids and added a sweetness. It eliminated some of that slight "grit" that I don't care for. The harmonics actually sound better to me with a sweeter tone.

Just thought I'd past that on.  Maybe being a single ended amp played a factor in this working so well?

With respect, Tubenit

[jojokeo]

One thread where we (all) had talked about smoothing caps, Sluckey suggested adding a cap from the grid pin to the cathode pin. I initially tried a 22p from plate to cathode and the amp squealed like crazy

Don't know why this would be? PP amps use a _ _pf all the time w/out issue and also Fender CBS amps used these this way to remedy osciallation but not have it cause it!?

It did smooth out the highs and upper mids and added a sweetness. It eliminated some of that slight "grit" that I don't care for. The harmonics actually sound better to me with a sweeter tone.

That's good to hear. What difference is there btwn going grid to cathode rather than ground?

[tubenit]

What difference is there btwn going grid to cathode rather than ground?

Great question! And I have no idea? I didn't try it both ways. I just took the example Sluckey provided.

With respect, Tubenit

[tonewood]

I think it would sound the same going to either cathode or ground since there is a 50mf bypass cap to pass everything from the cathode straight to ground.

[sluckey]

What difference is there btwn going grid to cathode rather than ground?

I would not expect much difference if any at all. Grid to cathode is always convenient directly on the socket but grid to ground may not be convenient depending on layout.

Another easy trick is a small cap between grid and plate. This also reduces high frequency and may reduce harsh glassy sounds, ie sound smoother. This method offers local negative feedback rather than just shunting highs to ground. It may have a different sound. The only amp I have that uses the plate/grid cap is a Sunn Sceptre. The cap is on one pole of the Mid Boost switch.
 

[TIMBO]

HI guys,If i was to add this to a PP amp, one per tube? and any type of tube?