Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: pbman1953 on December 18, 2023, 04:06:13 pm
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I have Super twin amp and Studio Bass amp.
Both are very similar, and one was made as a bass amp and the other a guitar amp
I see on the front end of each there a few different values used so I'm wondering what the values would do the sound.
Studio Bass-V1A- 7025A- pin 6 goes to a 330 K and a .0012 cap
Super twin- V1A-7025a- pin 6- The difference on this is that there's a 100k and a 330 pf combination
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Studio Bass- 7025b- pin 3- has a 2.7k to ground
Super Twin- 7025b- pin 9 has a 820 ohm on the Reverb Model , but a 1900 ohm on the non-Reverb model
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Studio Bass- v3 12ax7- pin 7 to a 2.7k to ground. Pin 8 750mf cap & 1.5 k to ground
Super twin- v3 12ax7- pin 7 to a 3.9k to ground. Pin 8 1mf cap & 1.5 k to ground
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41 views and no comments?
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Your questions are rational, but there are a lot of them and going back and forth between two large schematics is a lot of work.
For the first comparison, the Studio Bass tone stack takes the frequencies < 100Hz down about 10dB.
Check out http://www.guitarscience.net/tsc/bigmuff.htm#RIN=1k&R1=39k&R2=22k&RM=100k&RL=1M&C1=4n&C2=10n&RM_pot=Linear (http://www.guitarscience.net/tsc/bigmuff.htm#RIN=1k&R1=39k&R2=22k&RM=100k&RL=1M&C1=4n&C2=10n&RM_pot=Linear) and play around with the Tone Stack calculator.
Or, download the Duncan Tone Stack Calculator if you use Windows.
The second batch did not match up with the schematics.
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Your questions are rational, but there are a lot of them and going back and forth between two large schematics is a lot of work.
For the first comparison, the Studio Bass tone stack takes the frequencies < 100Hz down about 10dB.
So you're saying that the combo takes out 100hz before any anything? Why would they take out so much?
Correction-
Studio Bass- 7025-v1b- pin 3- has a 2.7k to groundSuper Twin- 7025b-v1b- pin 3 has a 820 ohm on the Reverb Model , but a 1900 ohm on the non-Reverb model
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Studio Bass- v3 12ax7- pin 7 to a 2.7k to ground. Pin 8 750mf cap & 1.5 k to groundSuper twin- v3 12ax7- pin 7 to a 3.9k to ground. Pin 8 1mf cap & 1.5 k to ground
The Super twin had 2 models, A Reverb and a non-Reverb model. My version was a combo of the 2 so maybe mine was made mid-way before they sold the Reverb. Mine doesn't have Reverb.
Thanks for this-
Check out http://www.guitarscience.net/tsc/bigmuff.htm#RIN=1k&R1=39k&R2=22k&RM=100k&RL=1M&C1=4n&C2=10n&RM_pot=Linear (http://www.guitarscience.net/tsc/bigmuff.htm#RIN=1k&R1=39k&R2=22k&RM=100k&RL=1M&C1=4n&C2=10n&RM_pot=Linear) and play around with the Tone Stack calculator.
Or, download the Duncan Tone Stack Calculator if you use Windows.
The second batch did not match up with the schematics.