ridiculously simple cab sim : /

[deadastronaut]

squeeeeelllllllllllllll....

i put a 100pf on input, as when input was open it squeellllllled..... this sorted it,

heres where i am.... a 1 pot cab sim. 




edit, new clip ,  cab sim off....then on.

https://dl.dropboxusercontent.com/u/7464107/WAVES%20FOR%20PELLE/simmo.mp3

[rutabaga bob]

All right, now let's get this straight: good to go, in only 3 pages?!  You expect us to believe that? 

Nice one, Rob!

[Groovenut]

Rob,

What is the purpose of R3? What is the anticipated load for IC1B? 600R?

Thanks,

Law

[deadastronaut]

hi law,

just to be more like bypass unity level really...

any suggestions are welcome as always...

[anotherjim]

I dunno, R3 at 47k should, if the opamp was perfect, be no different than a short = unity gain. Ooo... What chip is it Rob? I mean the -input is really high Z, so high that 47k is not significant.

On breadboard, the extra stray capacitance might be making a filter with the 47k that's just audible - I dunno - but that capacitance will be much reduced when built on pcb.

C5 at 100n is a little skinny for full bass end into a 10k mixer line-in  - but that may be helping to sim the low end roll-off of a real cab 'cause it's around 200Hz. Just saying be aware that 100n into 100k or higher inputs will lose that bass cut. C5 at 470nF at least if you'd wanted full range into 10k.

If you want a fixed low end roll-off no matter what it's driving, add a series cap before R2 and then make C5 wayhuge - 10uF!

Then Lawrence can drive his 600ohm.

[deadastronaut]

Cheerz jim, its an 072..

i,ll try that series cap thingy.,

[PRR]

> my cheap BB, ...  Thing is unshielded in any way

Find a rich-person doing copper roof flashing<g>, grab a half a foot scrap, goo it to the bottom of the breadboard, and ground it.

[J0K3RX]

Copper foil tape you can get at Lowes, walmart, HD or the stuff from StewMac is good

[deadastronaut]

Copper clad board screwed or glued to the bottom, and grounded??...

[GibsonGM]

> my cheap BB, ...  Thing is unshielded in any way

Find a rich-person doing copper roof flashing<g>, grab a half a foot scrap, goo it to the bottom of the breadboard, and ground it.

LOL   I do have some scrap.  Good idea! 
However, I'm time-wealthy, money limited!




Rob - yes, putting a (grounded) sheet under your breadboard can provide a nice ground plane to pick up RF from your environment.  Every little bit helps - even better if you made a Faraday cage and placed your BB inside it, ha ha.  Even aluminum foil will work.

[deadastronaut]

been eyeing up mrs astros tins ....

but i'll likely make a dedicated hi gain TB/BB with copper under it..

anyway..

jim, tried the 470n C5 , and a cap before the 1k..

but it lost the bass somewhat......

(this is going into a passive DI btw)

[bluebunny]

been eyeing up mrs astros tins ....

If you don't fancy eating all those biscuits, treat Mrs Astro to a takeout curry this evening.  Keep the aloominum dish the rish comes in, clean it, trim, ...   

[deadastronaut]

aha...she has some of those too.... 

[anotherjim]

Rob, do you know the input impedance of the D.I. Transformer? Could be 600ohm, then output cap bigger than 470n or you will lose bass.

[deadastronaut]

hi jim, no i dont know...

its this cheapy one, very little info on it...

http://www.staggmusic.com/en/products/view/SDIST

[anotherjim]

Weird! No data at all for that Stagg D.I. If its transformer, your output cap value is a somewhat different interaction than if it was feeding an active D.I. with resistive input impedance.

Thing is, if you're unlucky, you have something that only sounds as intended with that particular D.I. Although I can't say how much different that would be from an active D.I. with High-Z input or some other make of passive. I'd expect any difference to be in bass response, which might not be a serious problem since there often is tone control on whatever its feeding. Using a High-Z buffer pedal should simulate an active D.I.
If the D.I. or whatever does not have a High-Z input then there will be obviously less bass if the output cap isn't big enough.

[deadastronaut]

cheers jim,

just thought i do have an active DI too..

https://static.bhphotovideo.com/lit_files/84887.pdf

i'll test that and compare...


that stagg does have 2 transformers in it...

[deadastronaut]

well going by the results, it seems best to

add a switch at C5 for 100n and 470n.

depending on whether its into a DI, or straight into a line in.



the active DI was pretty nasty...

[GibsonGM]

Now, you put a cap before R2, Rob?  What value, just 'arbitrarily large'?

A switch might be a good idea, that will cover several possible situations...

[deadastronaut]

hi mike....nope..

but i will tinker...


ive added the switch...just testing..

and comparing line in and passive DI


edit: yep switch is cool....good for both DI/line..


PASSIVE DI = 100n nice n bassy...  470n nice n tight

LINE IN  = 100n nice n tight ....470n nice n bassy...