Hey everyone,
I found a review online for my old Crate CR 112 that suggested upgrading the power amp transistors from TIP110/TIP115 to  nte2343/nte2344 and the preamp opamps to OPA 2134.  No other instructions beyond that. It looks like the nte2343/nte2344 combo is just a little more robust overall, and 80 watts vs 50 with the TIP's. Would these NTE's work as a drop in replacement in this circuit and if so what/ if any improvement would they really offer? I'm assuming it wouldn't really be much louder? (The watts vs db's ratio)

The main problem I'm having is what I believe is harmonic distortion coming from the boosting circuit in the feedback loop of the 2nd half of the 4558 opamp. Ear stabbing sound pressure harshness unless the mids and bright switch are off.
It actually sounds like piercing, whistling overtones. What I dont know is if the harshness is coming from the boosting within the opamp itself, or if the boosting from the op amp is hitting the transistors too hard downstream in the power amp causing harmonic distortion there. Hence maybe beefier transistors would help? Anyone have any ideas?

I've already had some good suggestions for mods to the first op amp loop in this circuit from forum members in the past, and after tinkering alot with the preamp circuit in a simulator, and learning to use a simulator in general, I have some plans for that section.  Many thanks for the help in the past. I'm using this amp circuit to learn about electronics. Thinking about this amp gives my mind something to do other than be anxious.     Of course, a hemp cone speaker might be all I really need, but then what would I learn?  Schematic is in the manual attached.

Hello everyone,

I am wondering if anyone can help me with this tonestack.

I basically want to convert to a standard fender tonestack with the component values adjusted for SS. As I understand I can divide by 10 for the resistors eg. 250k for tube = 25 k for SS. Is that true? I read it somewhere and cannot find the original source now. What about the caps though... how does one convert the values for those?

I would like to load this tonestack into the Duncan tonestack calculator but it is not a perfect match in its layout. The .22 cap is located on a vertical line between the bass pot and the mid resistor, rather than on the horizontal lines, and there is only one cap instead of two. My limited knowledge doesn't know how to interpret this. How could I plug this into the fender format in the Duncan calculator so I can see the frequency response? As the calculator wants a cap on each horizontal line in the tonestack. Are both the Bass pot and "mid" resistor to ground below that sharing that .22 cap?

As I understand it the mids in this amp are active as they run back through the feedback loop in IC1. My idea was to just jumper the mid pot or introduce a fixed resistor to negate this active section...and then hook the leftover unused mid pot up for a passive mid at the bottom of the tone stack proper, for a more traditional mid section ala Fender. Attached is the full tone section of the schematic, as well as just the tonestack for reference.

Many thanks to anyone who would like to help

-Shawn

Hello all. I have a Crate Cr112 that I have been entertaining modding in the tone stack section. Overall the clean tone is sort of lower mid focused, I think. To get the sound I want I have to set the treble around 5-6, mids completely off or just a tiny bit. Bass around 3. I'm losing a ton of volume this way but it gets unpleasantly punchy anywhere north of that. My ideal clean sound is Jerry Garcia like, which is basically a twin reverb. I know, buy a twin reverb. Not an option unfortunately. The bright switch adds alot of character and the amp seems to come to life with it on but it is wayyy to harsh sounding. Sounds like a mid boost fat switch more than a bright switch.
Maybe just an efficient speaker like the swamp thang to counteract the volume loss and possibly audio taper pots would do the trick?

I once had an oxford speaker from a late sixties bassman cab that made the bright cap more usable.
Schematic and manual is here. Many thanks for your time if you want to look at it. The tone stack doesnt seem to really match anything in the duncan tone stack generator.

https://supportloudtech.netx.net/loud-public/#/asset/2383