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Jim Root Terror Schematic?

Posted: Sat Feb 06, 2021 1:53 am
by psychepool
Hello.
I've seen someone here talking about the value of parts for the Jim Root Terror, but I can't find it.

I heard that the JRT differs in some component values ​​on the same circuit as the Rockerverb / OR15.

Can anyone tell me the exact details of this?

Re: Jim Root Terror Schematic?

Posted: Sat Feb 06, 2021 3:55 am
by bclaire
Haven't seen a schematic for this amp....

Re: Jim Root Terror Schematic?

Posted: Sun Feb 14, 2021 12:15 pm
by Jondog
Not a lot of difference between the two. There are 4 component differences. Both amps have a preamp that is very similar to the Rockerverb mkl dirty channel preamp, I've yet to see schematic for MKll and MKlll so I don’t know exact values in those amps but will be similar if not the same. JR has basically the same tone stack as the Rockerverb and the OR15 has the same second stage coupling cap as the Rockerverb. Other than that everything else is the same, including the power amp, power supply, bias and negative feedback.

It seems when I start writing capacitor and resistor values the forum blocks me for potential phishing. Must be new software being used or something. I’ll have to simplify it.

Re: Jim Root Terror Schematic?

Posted: Sun Feb 14, 2021 12:21 pm
by Jondog
Had to remove some brackets and colons to get it to post

Second stage coupling cap, JR= 4n7 OR15=2n2
Tone Stack slope resistor, JR= 39k OR15= 47k
Tone stack treble cap, JR= 1n , two in series OR15= 470pf , two in series, essentially half capacitance in the OR

Re: Jim Root Terror Schematic?

Posted: Sun Feb 14, 2021 1:57 pm
by Jondog
Almost forgot, the enclosure and graphics are different :lol:

Re: Jim Root Terror Schematic?

Posted: Wed Feb 17, 2021 5:12 am
by psychepool
Jondog wrote:
Sun Feb 14, 2021 12:21 pm
Had to remove some brackets and colons to get it to post

Second stage coupling cap, JR= 4n7 OR15=2n2
Tone Stack slope resistor, JR= 39k OR15= 47k
Tone stack treble cap, JR= 1n , two in series OR15= 470pf , two in series, essentially half capacitance in the OR
Thank you for your reply and apologize for the late read.

I have a schematic of Rockverb and OR15.
I checked the information you gave by comparing the circuit diagram above.
Since it uses (almost) the same tone stack as the Rockerverb,
- Difference from Rockerverb : 2nd stage coupling cap (RV : 2.2n / JR : 4.7n), 3rd stage cathode resistance (RV : 2.2K / JR : 1.5K)
- Difference from OR15 : 2nd stage coupling cap (RV : 2.2n / JR : 4.7n), slope resistance (OR : 56K / JR : 39K), treble cap (OR : 2 x 470pF / JR : 2 x 1n)
Can I think this way?

As a result, the Jim Root Terror is seen as a model with more open bass and slightly increased gain in the Rockerverb preamp.
Or, I can think of it as a model that opened more bass in OR15 and emphasized high mids in tone stack.

Jondog wrote:
Sun Feb 14, 2021 1:57 pm
Almost forgot, the enclosure and graphics are different :lol:
It's most important point may be!
Anyway, It your reply was very helpful. Thank you again!