Dave Barber is a sick man...

[WGTP]

I guess this is a stupid question, but how come the inputs and outputs don't have to be buffered when stacking op amps?  

[Dai H.]

neat idea. I know someone who tried paralleling a transistor in a wah. He didn't know if it was okay, but reported interesting sounding results.

[javacody]

I stacked two lm386's. Let me tell you, they got hot real quick. Almost hot enough to burn my finger. I ain't tryin that again.  :lol:

When stacking opamps, the input and output would already be buffered from the first opamp, right?

[David Barber]

Some of the op amp mixes will "fight" each other a bit if you do not use isolation resistors, I posted this about a 10 days ago with pictures to show the basic method. You can also cut out the part of the op amp that is not of benifit and only parallel one side.

We really like the stack circuit method that I posted a while back, with a clean blend/boost connected and isolated op amp, parallel with the overdrive. This is simple and a cheap way to "wake up" dist/OD that did not seem so exciting without the plugin clean blend.

There are lots of possibilities, but excersize some judgement, you might need a heat sink of some isolation resistors when the chips have properties that call for it.

David

[Mike Nichting]

DAVE, I stacked 2 4558's in my TS9 and it sounds great. The only problem is that it goes out every now and then. I have them in a socket and I have to hit the pedal to get it to work. They are all the way in tho.

Any suggestions???

Thanks Bro,
Mike N.

[Joe Hart]

Forgive me if I'm a little slow, this may have been done before... Could you parallel the two halves of a dual opamp (say a 4558) just by soldering the pertinent legs together? Who's tried this and how did it work? Are the specs too similar to make much of a difference? I just figure that it's a very simple mod, and you don't need another opamp, and you wouldn't even need to pull the chip out of a circuit. But if it won't make much difference in sound, then forget it! Thanks.
-Joe Hart

[smoguzbenjamin]

If only one half of the opamp is neede you can solder the respective lugs together. Sure, why not?

[Phorhas]

If we stack differant Trannies (Fets, BJT, etc...) wouldn't one of them be misbiased?
and can we stack two differant TYPES (i.e. BTJ and FET or MOS) altogether?

[petemoore]

Because FET's have no current at their bases, piggybacking them will make no difference...
 Someone said that, and it makes sense...no current flow..no current to mess with then.

[WGTP]

Anyone come up with some wonderful combinations?

[bobbletrox]

In an Opamp Muff Fuzz:

LM833:  scooped mids sound, crisp highs, more gain
4558:  warm mids, bit of noise, less gain

4558 w/t LM833 on top:  warm mids, more gain, crisp highs

The tricky part was soldering them together  :oops:

[puretube]

http://www.national.com/an/LB/LB-44.pdf

[Peter Snowberg]

Very informative bump.

[Alex C]

Yes, nice one.

I looked at Rodgre's original post date, December 15, and I couldn't believe I had missed this thread.  Then I realized it was an entire year ago.  Seems like yesterday...

Alex

[javacody]

I forgot about this cool thread. However, recently in tweaking my RunoffGroove Ruby amp, I decided to try two J201's in parallel, and it really fattened up the tone. It got me just a hair closer to tube tone. I wonder what it would do in some of the ROG amp sims?

[B Tremblay]

However, recently in tweaking my RunoffGroove Ruby amp, I decided to try two J201's in parallel, and it really fattened up the tone. It got me just a hair closer to tube tone. I wonder what it would do in some of the ROG amp sims?

In the midst of our amp emulator development, we did try out a FET version  of the Matchless Clubman 35.  The first stage used a pair of J201 in parallel and there is indeed an audible difference, but it's difficult to quantify.

Is your Ruby build stock, with the FET as a buffer?

[Dragonfly]

Damn I am too late! I was coming over here to post a new tweak link.

Try the TL072/4558 combo. Don't forget some combos will fight each other and some are magic...break out the usual suspects and start soldering! Combos of three or more are more difficult to get a winner, but two is usually a charm. The BB2604 can be a tough one to mate.


David

good to know !!!!

a friend and i played with stacking op-amps about 6 months ago, but we had "limited" success....obviously we were using the wrong combos and probably abandoned the idea too soon.....nice to know our "uneducated theory" was correct

David...you RAWK !!!!

[WGTP]

OK, who is going to draw up a Tube Screamer schematic, for those off us too challenged to convert that info into Sonic Reality?    

[javacody]

Schematic? Just stack some opamps. Wasn't it John Lee Hooker who said you don't need any fancy schematic, as long as you got the beat?  :lol:

Brian, I made the bassman modded ruby, but other than that it is stock, so yeah, the JFET is a buffer.

[WGTP]

I like that.  "You don't need no schematic as long as you got the beat."

After I typed that, it occured to me that was probably what it looked like if you had a schematic of stacked op amps.  I'm sort of slow.