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Summary of Contents for Ceriatone JTM50
- Page 1 JTM50 50W Amplifier User’s Manual...
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Page 2: Table Of Contents
JTM45 and a 50W smallbox bass amplifier. For players looking for the sweetness of a JTM45, but with more midrange grind and a firmer bottom end, the JTM50 delivers in spades. -
Page 3: Quick Setup
2) QUICK SETUP (for instant gratification) 1) Plug your guitar using a 1/4” instrument cable into the upper I input on the right of the front panel 2) Plug a suitable power cable from the Plexi’s rear panel MAINS cable inlet to your wall power receptacle 3) Plug the Plexi into your speaker cabinet using 1/4”... -
Page 4: Front Panel Controls
3) FRONT PANEL CONTROLS From left to right: 1) POWER 2-way toggle switch 2) STANDBY 2-way toggle switch 3) INDICATOR LED 4) PRESENCE control 5) BASS control 6) MIDDLE control 7) TREBLE control 8) VOLUME I control with Push-Pull Bright boost 9) VOLUME II control 10) INPUT I and II input ¼”... - Page 5 INPUT I and II are ¼” jacks for instrument cables. Plug your guitar in here. Use the I input for the BRIGHT channel. The BRIGHT channel has more gain, more treble, and a more prototypical JTM50 tone. The UPPER I input is higher gain, whereas the LOWER I input is lower gain.
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Page 6: Rear Panel Controls
10) MAINS IEC cable inlet SEND ¼” instrument jack can be used to directly interface the preamps of the JTM50, thereby bypassing the power amplifier. Conversely, this is usually used as the SEND of the effects loop. Plug the input of your effects unit, or interface device (ex – C-... - Page 7 RETURN ¼” instrument jack can be used to directly interface the power amp of the JTM50, thereby bypassing the preamp and using the amplifier as a power amplifier. Conversely, this is usually used as the RETURN of the effects loop. Plug the output of your effects unit, or interface device (ex –...
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Page 8: Tube Compliment And Bias Adjustment
5) TUBE COMPLIMENT AND BIAS ADJUSTMENT From left to right: V1 – 12AX7/ECC83 (Input stage Bright and Normal channels) V2 – 12AX7/ECC83 (stage 2 and tonestack cathode follower) V3 – 12AX7/ECC83 (phase inverter for power amplifier) V4 – EL34 V5 – EL34 V6 –... - Page 9 …and now some math. The formula for calculating bias is as follows: �������������� ���������� ���������������������� × �������������� ���� �������������� ���������������������� × 1000 = �������� �������������� (����) ������������������ ���������� �������������� In most cases, amplifiers are biased between 50% and 75% dissipation. We bias the JTM50 to 35mV reading on a DMM.
- Page 10 An example is as follows: 25�� × 60% × 1000 = ���������� 35���� 420������ You might wonder why your DMM is set to millivolts and not milliamps – simply, we have a 1 Ohm resistor placed between your probe jacks and ground to convert a current reading to a voltage reading. That way, a bias current of 35mA measures as 35mV on your DMM.
- Page 11 Biasing should only be done on a clean workbench with no distractions. Do not wear loose clothing or any jewelry. Take your time, and think carefully before each step. Again, bias at your own risk. Ceriatone Amplification is not responsible for any damages or injuries resulting from user biasing.
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Page 12: Frequently Asked Questions
6) FREQUENTLY ASKED QUESTIONS How do I hook up this thing? - See Section 2, beginning on page 3. Is the FX loop series or parallel? Active or passive? - The FX loop is series, and is currently passive. However, we have plans to release an option for a tonally transparent solid-state FX loop. - Page 13 Can I substitute different tube types? - Although you can try 12AT7s, 12AU7s, 5751s without any harm, the design is optimized for 12AX7s, and are therefore the only recommended tube in the preamp positions. Use only EL34s and a GZ34/5AR4 rectifier tube.
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Page 14: Settings Templates
7) Settings templates...
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