Any cab simulator circuit worth building?

[J0K3RX]

Great job yeraym!! Hope you like it as much as I do!

Here's another stupidly simple one but sounds great...

[yeraym]

Thanks J0K3RX, I really like this low parts count cab sims. For any one interested in more complex designs, there's lot of info here: http://www.hexeguitar.com/diy-cabsims_e

[BubbaFet]

As a point of comparison, there is a fine series of frequency response plots
for the Tech21 VT Bass speaker sim pedal at....
http://www.talkbass.com/forum/f15/tech21-vt-bass-wheres-magic-607213/

[pappasmurfsharem]

*Deleted* Opening a new thread.

[petey twofinger]

http://guitar-gear.ru/index.php?p=proj&id=59

any vero layout for this yet ?

been dying to build a stereo unit , but i can not wrap my head around how to make vero layouts ...

[jishnudg]

There was a 'MultiCab' sim design that was floating around here sometime back...rather nice,that one.

[DougH]

I built this yesterday and tested it with a punch amp which I have yet to box up, and this will definetly go inside the box with it, it sounds really good. I used my own vero layout:





I built it with 2N3906 / 2N3904 as thats the only PNP / NPN pair I have at hand right now, but I simulated it in LTSpice before. Here is the plot for BC560C / BC550C, 2N5087 / 2N5088 and 2N3906 / 2N3904 pairs.



As you can see, there is some difference depending on the pair series you use, mostly between 2N390X and the others. But teemuk's post got me thinking, if I replace the followers with opamp followers what would be the frequency response look like? I tried to simulate it, please if someone sees and error in my "translation" to opamp based version tell me as I'm not sure I did it right.



Here is the resulting plot:



It looks to me that the original BJT based design is making use of some transistor parameter but I fail to see what it is. Could someone who knows please stand up and explain it?

Op amps drive a lot more current than BJTs. You can limit their current drive with a series resistor on the output.

From the looks of those freq curves, IME I'd want a little more of a peak at 4kHz before the sharp dropoff at 5kHz.

[slacker]

http://guitar-gear.ru/index.php?p=proj&id=59

any vero layout for this yet ?

I built it on vero, can't remember offhand if I did a layout or not, I'll have a look.

[petey twofinger]

ty !! i have my heart set on the hotline per jokerx's rec .

[pulse]

Thank you J0K3RX, YerayM, and please convey thanks to Lart!

YerayM I wonder could you make your ltspice files available? I'd like to modify the Simple CabSim to match the frequency response of an SVT 8x10 bass cab. This would give me a head start. Anyone happen to understand how the different rc filters in this thing work? Worth figuring out I think compared to the complexity needed with other designs.

[J0K3RX]

Thank you J0K3RX, YerayM, and please convey thanks to Lart!

I'm pretty sure Lart is from Ukraine... I believe Ukraine is in the middle of a crisis right now

[pulse]

I'm pretty sure Lart is from Ukraine... I believe Ukraine is in the middle of a crisis right now

I'm hoping Lart lives far away from the war zone, but sucks either way :-/ Normally I try to hide from world affairs, but after reading the amazing discussions on cabinet simulators in the Russian forums including much input from Lart, it's really making me sad :-| I do not see any fighting between Russia and Ukraine in the Russian guitar forums though, hope for us all.

[Willypp]

I've built the Marshall vero on Sabrotone, and it's pretty good but it's probably too severe in it's filtering (at least in the original layout - I'm about to build rev2), I also have a Ultra-GI which is ok but probably not quite there and I'm about to build the Simple Cabsim Jokerx posted above... but what I'd really like to see traced is the cab sim in my HT-dual.  That has an awesome cabsim, to the point where I used to use that as the pedal's output into my marshall vs102r 2x12 combo. Also sounds great DI'd.

[Willypp]

Just built that simple cabsim v2 from the layout above, but I subbed a 2n5459 for the j201 and I've got nothing coming out the other end.  AFAICT they have the same pinout and I have no solder bridges... any ideas?  I've used the BC560C and BC550C as per the layout.. 

[Kipper4]

I Notice from the soldered board and Vero layout that Q2 and Q3 are back to front.
Take note of the transistors flat sides. either the layout or the board have errors.

[J0K3RX]

I Notice from the soldered board and Vero layout that Q2 and Q3 are back to front.
Take note of the transistors flat sides. either the layout or the board have errors.

If you're referring to the vero layout by Doug then you may want to have a look at it again... You can't really just go by part orientation with vero stuff since it snakes in and out and can change directions without notice. So, while Q2 and Q3 appear to be facing the same direction the actual circuit is not.. So, I doubled up on my ADHD meds and had a quick look at the vero.. looks correct to me but, I reserve for the possibility of being wrong since my brain can only stand about 5 minutes of vero madness before I become distracted by the spot on the wall... 

I would double/triple check the layout and make sure all of the little red cuts are accounted for, 7 I think? I have only made these using etched layouts and I have only used J201, BC550C and BC560C so, I can't really comment on any others.. But, I don't see why others wouldn't work except they may not work from +5v up to +40v to be used in a wide variety of tube preamps like the original Lart design. In any case I have made scores of these and have not had one that didn't work as the one before etc.. and they all sound consistently the same. As I said before, I like this one the best of almost all of the sims I have tried including some expensive ones! I have what I consider to be some pretty good studio monitors (PreSonus Sceptre) and I have tested this cab sim against mic'd Marshall cabs with various speakers and "to my ears" this sounds the closest. I think the other thing about it is that it has a very real feel.. dynamic, and responsive to harmonics which really come out if you are chuggin on some high gain metal guitar sounds...   

[duck_arse]

the spot on my wall is present and correct. the Q2 and Q3 are correctly shown for the BC series transistors. the note "(try other pnpn eg 2Nxxxx)" should include a note to the effect that the 2N series is backwards/opposite/reversed to the BC pinout. so the built board would be showing 2N series, the drawn layout showing BC series.

and mind the double link!

[Kipper4]

Gottya thanks for the clarification Mr 3k

[Willypp]

Yeahnah.  I've checked my orientations and all the rest of it, cant find the problem.  Even changed the direction of the 2n5459 to see if that was the problem.

It's obviously not as I'm getting the same nothing as before...

[bool]

One possibility is that your subbed fet has too high Vgs, datasheet shows 4,5V, so the circuit doesn't bias properly.

You could try to sub a regular npn BJT for the FET (in this particular circuit) to test if the rest of it works.

Of course, if everything else is _as_should_be_ ...