With the switch open you have the High Input and switch closed you get the Low. The reissue 68 Custom Deluxe Reverb cuts NFB in half by using a double size 1. The Tone Stack is a series of three RC (resistance capacitance) audio filters that block three bands of audio frequencies. For the 68 CDR style mod simply connect the top of Resistors R23 & R11 with a jumper wire and clip or remove cap C5 (both mods upper left in layout above). This is an Ice Pick Cap on a 5F6A Bassman but it works the same way in the AB763. The B triode is a 12AX7 equivalent so the V4B preamp stage stays at full gain. 0047uF Cut Cap can be supported by a non-grounded terminal strip. It serves as the entire tone stack's ground connection. The factory 5E3 has a Low input impedance 138k and grid stopper resistance of 68k but this mod will give us a tone that's so close to factory that I'll buy you a case of beer if you can hear a difference. You will probably need to adjust the bias when running two 6V6 tubes. Deluxe reverb tremolo not working on my. It is important that the V1 tube is a high quality tube with little noise. These tubes can be harder to locate since the error is not reproducable. Adding a fixed, high voltage screen grid makes a tube much more efficient because the screen's constant strong pull of electrons does not drop when the plate's voltage drops so the tube flows more electrons.
It's purpose is to filter out unneeded high frequencies which helps cut noise and prevent oscillation in the sensitive reverb circuit. Alligator clip the new cap's + terminal to the first large cap's + terminal and connect the - to -. 5k NFB resistors so you can select normal 65 DRRI feedback or no feedback or 68 CDR feedback. Fender Modern Hand Wired Custom 64 Deluxe Reverb. As you roll in more Mid control the mid scoop is removed and the signal is boosted across the frequency spectrum. The Custom 64 Deluxe Reverb currently sells for $2500 at Sweetwater. Hi/Low Input Switch. Deluxe reverb tremolo not working full. Bias shifting trem in fixed bias amps that vary power tube bias have several issues: 1. This very cool 1/4 Power Switch is from the 20 watt Fender Eric Clapton Tremolux. Power tube shifting trems are generally more common and found in fixed bias amps. 100KA Mid/Raw pot with a 6.
I don't recommend this because the box would have to be really big to provide an adequate heat sink for the big resistors. This can also sound like a terrible and scratchy noise when you play certain notes/frequencies. Less resistance = more signal mix and less output volume.
By preserving the Normal channel coupling cap we can use it to voice the channel such as in the Lead Channel Mod. 0047uF coupling cap is standard in many modern high gain amps and will trim unneeded low frequencies to tighten up the overdrive tone. The stacks' output flows directly into the Volume pot. If you want to be thorough then replace every resistor except for the higher watt rated voltage dropping resistors located in the capacitor "dog house" between the filter caps. Adjust Reverb Level Mod Want to change the action of the reverb control? As guitar notes decay their harmonic overtones cause varying amounts of phase shift through the tone stack which causes the actual wavering "shimmer" effect. A number of amps to today use solid-state tremolo circuits and have excellent sound. These 25 watt resistors are adequate for 15 watt amps such as a 5E3 Deluxe or other cathode biased 6V6 push-pull amps. Run 6L6 Power Tubes In 6V6 Amps. Types of Tremolos in Tube Amps — 's Custom Amps. As long as the Bandmaster Reverb is connected to a 4 ohm speaker load (typically two 8 ohm speakers) the outcome is the same.
Click the image to see the full size version. "The ET65's creamy lows blend with tight midrange and sparkling highs for some of the best tones ever created. Reverb recovery and 2'nd gain stage for the vibrato channel. Negative feedback is cut in half by doubling the size of the NFB resistor. Note the "Optional Tremolo Load Resistor" at center left of the circuit board.
By adding a switched large parallel 10uF or larger (250v or higher) capacitor we can send all frequencies to ground and create variable NFB. You'll also be able to run more reverb with the Lead Channel because the very low freqs aren't there to freak out the reverb circuit and springs. I currently cannot do any sort of extensive repair, so only small things to check off the list first. The plate voltage will be higher with only two tubes pulling current through the power supply so you may need to adjust the amp's bias. Disconnect one end of resistor R9 and bend it to one side. You can place your master volume pot anywhere but you may have to use shielded wire to prevent noise or oscillation. Best reverb and tremolo pedal. Some tubes are noisy only when they're cold and within the first ten minutes after the amp has been fired up, while other tubes start to act noisy after some time. The C and D power (voltage dropping) resistors are located at upper-center left in the filter cap "doghouse. 8k resistor with a pot wired as a variable resistor. Darken the Reverb Tone Is your reverb tone too bright? In a bigger perspective we consider the brand of the tube to be less important for your tone than i. the guitar strings, pickups and speakers.
Just leave the mixing resistor in place. Here is what I have done to try and troubleshoot the problem. You don't need to modify the power resistor. I didn't get one (fuckin ebay eh). Adding Mid resistance adds mid frequencies and reduces the tone stack load which adds gain. Hi all, hoping someone could help me out and let me know what could be the problem with my vibrato channel. 5k or do the 3-Way Negative Feedback Switch Mod. Insert ON-OFF switch between power tube socket pin 8 (cathode) and ground. This is an excellent mod and I highly recommend it.
"Fritz" Mod Classic mod to send both channels through the reverb and tremolo effects. For some people the tone of old, weak and flat sounding tubes can be just what they want. Remove or clip a leg of the Vibrato Channel Bright Cap C10 located next to the Vibrato Volume pot. The first 1/10 of the Mid pot movement is equivalent to the entire original 10KA Mid pot. The V1A plate load resistor is R4.
Running a pentode in 'triode' mode definitely changes its clean and overdrive tone so it's more than just a 'half power' mode. First two filter caps on the right are connected in parallel. Wire the right terminal to the now empty right resistor eyelet (or turret). For amps with solid state rectifiers like the Twin Reverb and Single and Dual Showman you can plug the amp into a variac and turn down the amp's input voltage. Lots of folks ask me about what the difference is between types of tremolos in amplifiers. Modify the Normal Channel tone stack to match the 68 CDR Custom Channel. Corrupt tubes are far easier to notice than a worn and less efficient tube.
Pull the volume control up and you get raw/boost. The stronger tube you have the more you will push the power amp section. If you don't want to try multiple caps I recommend you go with a 32uF. This is a pretty common mod that allows a slower tremolo which I really like. With the switch lever 'IN' you get normal full power. You can add this resistor to any AB763 by replacing the wire that runs between the Bass and Middle pots (or Middle resistor) with an 18k resistor. This mod would be of relatively little use in the first gain stage anyway since it is rarely overdriven. Like most amplifier negative feedback loops this mod will reduce distortion, tighten the transition from clean to dirt and slightly reduce gain. Use a SPST mini switch to break the connection between the Bright cap and Volume pot center terminal. In the bigger and most powerful tube amps we don't replace tubes often to get max effect out of the amp. He solved the problem by placing a 100k resistor across the switch terminals. 018 milliamp) or less so it's not a concern. Channel Mixing Resistor Bright Caps Mod. Bias supply tap: 61VAC.