Low volume on "Simple Cab Sim Rev2"

[pappasmurfsharem]

Need a little assistance from the peanut gallery.

I built the Simple Cab Sim Rev2 from JOK3RX's post in this thread
http://www.diystompboxes.com/smfforum/index.php?topic=106185.msg959772#msg959772

It seems to work and might sound ok, but its about half the volume of the input. Is it suppose to be unity?



This is the redrawn scheme I put in eagle and board I had fabbed.
Notice i used 5087 and 5088
and R2 I used 1M instead of 1M2

[PRR]

> Is it suppose to be unity?

It is three unity-gain stages plus a LOT of stuff.

And obviously a highly bent frequency response.

The "stuff" could be narrow bumps (over unity) but more likely wide sags.

I would expect the "average" gain to be somewhat less than unity.

[pappasmurfsharem]

> Is it suppose to be unity?

It is three unity-gain stages plus a LOT of stuff.

And obviously a highly bent frequency response.

The "stuff" could be narrow bumps (over unity) but more likely wide sags.

I would expect the "average" gain to be somewhat less than unity.

It's well below unity for me. For instance on my Dr Boogie build that I was testing it with. I have the volume pot at about 9:30-10 Oclock for unity with the clean signal. When I engage the speaker sim I have to run the Dr Boogie at Max volume just to get Close but still under unity.

[PRR]

I'm astonished. It's all unity-gain amplifiers but the filter networks are so jacked-up that it "has gain" over most of the audio band.



> 10 Oclock for ...the clean signal. ...engage the speaker sim ...Max volume

That's radical loss.

Something is wrong.

DC check for gross problem. Source and both Emitters should be mid-way up the 9V rail, +4V to +6V.

Signal-trace. Source and both Emitters should have the "same" audio as the input jack, plus the bass/treble bumps.

[pappasmurfsharem]

I'm astonished. It's all unity-gain amplifiers but the filter networks are so jacked-up that it "has gain" over most of the audio band.



> 10 Oclock for ...the clean signal. ...engage the speaker sim ...Max volume

That's radical loss.

Something is wrong.

DC check for gross problem. Source and both Emitters should be mid-way up the 9V rail, +4V to +6V.

Signal-trace. Source and both Emitters should have the "same" audio as the input jack, plus the bass/treble bumps.

It is always something stupid isn't it...
My work area is not WELL lit (basement with some fluorescent lit) So I grabbed the multimeter to test the points you referenced.everything seems ok, then I realized that a leg Q3 had missed its socket  *facepalm*

But It's Alive! Woot.
https://soundcloud.com/nicholas-schaffrin/speaker-sim-test
1. Clean No sim
2. Clean w/ Sim
3. Dr. Boogie No Sim
4. Dr Boogie w/ SIM

[J0K3RX]

Sounds very good if you ask me!! Sounds very natural...

[pappasmurfsharem]

Sounds very good if you ask me!! Sounds very natural...

Indeed.

Thanks for the recommendation in the other thread 

I'm going to have a bunch of these fabbed up.

[J0K3RX]

Sounds very good if you ask me!! Sounds very natural...

Indeed.

Thanks for the recommendation in the other thread 

I'm going to have a bunch of these fabbed up.

If you do let me know... I might get a few from ya that is if you want to sell a couple?

[PRR]

> My work area is not WELL lit

One "secret weapon" is GOOD light.


Looks good in the picture but the light is all from the camera-flash (find the shadows). Unless it is only used to sort picture-hooks, it either has, or needs, more lights.


Looks good. However when sitting, the lamp is on the far side of the chassis and just barely above eye-level. For me and my projects, the glare would be intolerable. Which may be why he has the desk-lamp, to throw light at some better angle. (Also the lighted magnifier.) Note also the inbuilt ceiling lamp, which may help but clearly was not adequate.


He's got two 35W fluorescents centered over the work area. Probably excellent for many woodworking and small mechanical chores. IMHO, not enough for small electronics. My best bench was this but *two* two-tube lamps (140W of Fluorescent), plus the good general room light (two two-tube fixtures 10' up and 3' behind me).


This is a low-price version of what was COMMON back when humans built rados/TVs/computers by eye-hand coordination. A "serious" version would be 6' wide, have more/better shelving , and four 40W fluorescent lamps.


This is my *minimum*. Two 100-Watt incandescents centered front/back and splayed on the good old 4'-4'-4' triangle. Clip-on "brooder" reflectors are the best cheap fixtures. 23W curly-lamps will give a similar gross light but poor color. This leads to red/orange and green/blue confusion. I would at least have one incandescent for resistor-reading. If you use 100W incandescent, get the porcelain sockets; the plastic sockets are often rated for 60W max and fail badly when overheated. BTW a skylight is best for reading resistors (half each day), but few basements have skylights.

[J0K3RX]

Damn Paul!! 

[ggedamed]

Nick, how did you you do the recording? What was the signal chain?

[pappasmurfsharem]

Nick, how did you you do the recording? What was the signal chain?

Hehe your gonna love this.

Guitar -> dr boogie -> simple cab sim -> jam up plug ( basically an iRig) -> iPhone GarageBand audio recorder with slight reverb. No other effects. Audio recorder is the vocal option no extra guitar effects.

[ggedamed]

Thanks!

[Tony Forestiere]

Damn Paul!! 

*in a dejected tone* damn. Paul. Again.
Nice and efficient setup.
*jealously slinks away*

[PRR]

> efficient setup.

NOT my setup. (Can't you see the photoshopping?)

Random Google images  to show my opinions of "poor" and "good". The last one has the lighting stuck-on for illustration--- is a noce bench but was very dark.

FWIW: my present "bench" is totally covered with crap and junk, has a huge window which is more glare than light, plus 400 Watts of incandescents halfway across the garage. I can find my router; I lost a roll of solder for 3 years, only came to light when I pulled a hammer out of the shadows.

[J0K3RX]

You know... this would be a really good SMD project! No?  A great sounding cab simulator that can basically fit right on the jack... You could throw it in just about any preamp type distortion or even clean preamp pedal.

So, the "simple cab sim" not quite simple enough for you? How bout this one? I have built and I like it!

[pappasmurfsharem]

You know... this would be a really good SMD project! No?  A great sounding cab simulator that can basically fit right on the jack... You could throw it in just about any preamp type distortion or even clean preamp pedal.

I could get some sMD boards made if there was interest

[Willypp]

Sorry about the necro thread revival, but if there are any boards available I'm up for some!