Questions tagged [guitar-amplifier]

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How can I best diagnose this solid-state Fender Sidekick Switcher in need of repair? [closed]

I am working on an amplifier that belongs to my dad. The story goes that in probably 1993, when I was 2 years old, I got access to a Phillips screwdriver and took this amp apart while no one was ...
2 votes
2 answers
52 views

E-Guitar / Bass amplifier Effects-Loop: Is there a standard for voltage levels & impedances? [duplicate]

Musical instrument amplifiers often have an "FX-loop" with a pair of jacks which can be used to interrupt the default connection between preamp & power amp, to put the preamplified ...
4 votes
1 answer
616 views

Is it possible to use CRT tubes for audio amplification?

I was wondering if it's possible for me to use the tubes in an old CRT TV to build an audio amp (specifically a guitar amp). If not, would I be able to salvage something else (like an old radio) to ...
-2 votes
2 answers
74 views

How to add harmonic distortions to guitar amp? [closed]

I was reading about the carver challenge,(https://www.stereophile.com/content/carver-challenge) and read that he had added a series of potentiometers to one of his amps that had allowed him to ...
0 votes
1 answer
103 views

Grounding Li-ion battery pack to stop amplifier hum

I'm trying to connect a tube guitar amplifier to the Delta 1300 W battery pack by Echo Flo. The pack is not grounded, so I get a hum. Echo Flo suggested connecting the amp to a power strip, then ...
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2 votes
4 answers
316 views

I'm desiging a class AB amplifier with class A preamp, what are the problems with my design?

I'm attempting to design a class AB guitar amplifier with a class A preamp. I'm a novice and this is the first actual project I'm attempting. What are the possible caveats, as well as my choice in ...
1 vote
4 answers
279 views

Best way to reduce HF noise in OMA2134 op-amp preamp circuit

I have built the following electric guitar preamp which is mounted inside the instrument. The primary reason for doing is that there is a piezo pick up in the bridge with a very high output impedance ...
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0 votes
2 answers
126 views

Why can't I get any output when a speaker is connected to my common-source amplifier?

I'm trying to build a simple amplifier for my guitar. I created the exact same circuit as a common-source amplifier, I biased it on the necessary Q-point, and AC signals are decoupled. It worked ...
0 votes
0 answers
59 views

Extremely basic guitar amplifier

I've been attempting to make a very basic guitar/condenser microphone amplifier for a long time, and I think I'm getting close (this is the first time I'm reaching out for help on the matter). I'm ...
0 votes
3 answers
132 views

Output transformer in guitar amp produces sounds, while none comes through to the speaker [closed]

I built a Fender 5f1 Champ imitation. I've taken care to start it up gradually (first with no tubes, then just the 5Y3, then the 12AX7, then the 6V6 with the speaker connected and finally connected a ...
0 votes
1 answer
204 views

Can I use a laptop charger as a psu for a guitar amp?

My amp is a Blackstar core id 40 and has info in the back that says "Use 16V/3.5A DC Power Supply". I'm confused on this part though if it refers to dc being the input or a dc adapter. Found ...
-1 votes
1 answer
259 views

Class AB Amplifier With Single Supply [closed]

I'm designing an amplifier which is to be run off of a single 20 V supply (in the circuit, V+ = 20 V, V- = GND). Q2 and Q3 are used to bias Q4 and Q1. Since the circuit is running off a single 20 V ...
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0 votes
1 answer
277 views

Strange ringing/oscillation in guitar tube amp

So I finally finished building my guitar amp. It sounds great, except for one thing that occurs when gain is too high. What happens is that when I turn one of the preamp volume pots high enough ...
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0 votes
1 answer
56 views

Guitar Amp Humming (interference?)

So my amp worked perfectly fine in my old setup in another part of the house, but in my new setup it buzzes when I connect a cable, and with a guitar. I thought it was a grounding issue, but it didn't ...
1 vote
1 answer
118 views

DIY distortion pedal help

I'm trying to design a guitar distortion pedal, though it is not working as expected. The built circuit behaves differently than the simulated LTspice model. I currently do not have access to a scope, ...
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8 votes
3 answers
2k views

Why do most guitar amps have a preamp and a power amp section?

I have read that the preamp boosts the signal so that it is strong enough to send to the power amp section, but it seems like there must be more to it than that. Two thoughts I have had: The preamp ...
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1 vote
1 answer
120 views

Why does my guitar pre-amp lose it's offset?

I found a guitar preamp on the web after trying to build one myself and having no luck. This one works for a bit, but the offset part of the OP-amp slowly depletes. It's like C1 is charging up really ...
0 votes
0 answers
45 views

My Firebird electric guitar's bridge pickup is operating at a very low volume. What could be causing this and how can I fix it?

I have a Firebird electric guitar with two mini humbucker pickups. Both pickups have been good since I got it, but suddenly the bridge pickup stopped working. The neck pickup is fully operational, but ...
1 vote
1 answer
168 views

Guitar amplifier repair: burnt fuse, capacitor, what else?

A friend has asked me to take a look at his guitar amp: Peavey Valve King VK212. Problem: suddenly the amp stopped working during operation and the status lamp went off. First reaction: fuse ...
1 vote
3 answers
230 views

Need help for troubelshooting a modification to a reverb circuit on a guitar amp to an FX loop circuit

Sorry if I am redundant here. I am totally new to this type of site so I apologize in advance. I found a similar question on the site but I didn't know if it was still active and I think my question ...
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0 votes
3 answers
147 views

op amp biasing... why are voltage sources reversed biased +/-?

I'm still trying to understand the theory of audio signal processing, namely guitar amplifiers. The main thing that got me started down this path was a broken amp that I have. I have since figured ...
1 vote
2 answers
146 views

Is it normal for a Guitar amplifier to have dc voltage across the output before a blocking capacitor?

I don't tend to post questions on online forums so I apologise in advance if I've messed up here. I'm currently trying to work on an old transistor guitar amp and in taking measurements managed to ...
0 votes
1 answer
39 views

Guitar Amp Headphone OUT Jack. What Pot to use?

With a Guitar amplifier's Headphone out jack, I need to attenuate the signal about 80%, adjustable. Would a 1k Audio Taper Pot be my best choice? I am attempting to use the headphone outs of my 2 15 ...
1 vote
2 answers
446 views

Guitar amp "motorboating" after upgrading op amps

I've been repairing an old (~1982) Fender solid-state guitar amp. While I had it apart I took the opportunity to replace some of the RC4558 op amps with NE5532's in DIP sockets I installed. It was ...
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2 votes
1 answer
348 views

Analog Switch times for popless audio

If I am using a CMOS switch, how much do I have to slow down the switch time so that I don't experience a pop in my audio signal out of my amplifier and how would I accomplish that? The switch time ...
3 votes
1 answer
739 views

How to calculate impedance for reverb tank in a guitar amp

Background: I'm in the process of restoring a HIWATT HI-GAIN 50 COMBO Valve guitar amp and one of the issues it has is that the reverb dial has no effect on the sound. Attempted troubleshooting: ...
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6 votes
2 answers
938 views

Troubleshooting Hum in a Tube Guitar Amp

I have a Fender Deluxe Reverb Reissue guitar amplifier that hums whenever I turn on the reverb. It sounds like loud 60 cycle hum. The reverb effect is still applied, but is accompanied by the hum. ...
9 votes
6 answers
7k views

Fender Telecaster guitar makes loud humming noise, stops when player touches strings/metal parts

I have a Fender Telecaster that hums loudly--much more so than other similar guitars. It's a standard Tele with single-coil pickups. The humming noise stops when the player touches the strings or ...
1 vote
2 answers
107 views

Distortion is introduced when speaker is connected to the output of the amplifier

I have a circuit that implements a guitar amplifier (I ordered a couple LM386 but in the meantime I used an OP484). The following figure represents my schematic: (cap C2=10uF as well) The signal from ...
1 vote
0 answers
153 views

Why is my signal stronger in the positive than in the negative when i use 2n3819?

simulate this circuit – Schematic created using CircuitLab In the above circuit I have created a JFET amplifier for small signal purposes. When I run tests on the circuit, i get this weird ...
0 votes
1 answer
233 views

Valve guitar amp head with headphones only [closed]

I ordered Marshall DSL1HR valve guitar amplifier head. As you can see in specs it has built-in "Emulated line output". I know that a valve amplifier must be running with a speaker cabinet attached. ...
1 vote
2 answers
105 views

Replacing elements in a tube amplifier

I assembled a tube amplifier.According to the specified scheme (Old Russian radio "Record 66"). 1.What is the function of capacitors C9 and C8 ? 2.What will change the capacity of these parts? Will ...
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0 votes
2 answers
244 views

Converting 2.1V RMS DAC output to instrument level 6.35mm jack

I'm not quite sure how level and impedance bridging works so I am hoping for an illuminating answer! I'm generating audio with a PCM5102A DAC. The datasheet of the chip specifies a 2.1V RMS output ...
0 votes
1 answer
93 views

Static noise when electric guitar plugged into amp

I have an Epiphone Wilshire that is producing a "static" sounding noise when plugged into an amp. I removed the cover plate and found a loose, black wire (ground?). It looks like the wire is connected ...
1 vote
1 answer
1k views

How to find feedback resistor value?

I want to implement typical guitar preamp scheme, like following: I see, that it will have input impendance =2.2M...
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1 vote
0 answers
108 views

Portable Guitar Amp - Distortion, Volume & GND

I have tried following the given schematic There are 3 things I am unsure of (what I tried): The Volume 5k Potentiometer: I have tried adding a volume control to the schematic by placing the ...
4 votes
2 answers
352 views

DIY guitar effect - delay

I'm trying to build a guitar delay effect based on this schematic: (https://i2.wp.com/cdn.makezine.com/uploads/2009/09/echobenderrev02.jpg) I designed and oredered a pcb : https://easyeda.com/...
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3 votes
3 answers
438 views

Guitar preamp problems

I built the following preamp to use with guitars Basically the idea is to keep it on a single rail so that I can use it off the same battery with this power amp https://www.eleccircuit.com/bridge-...
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1 vote
0 answers
198 views

Is ripple voltage is too high?

I'm trying to calculate voltage ripples on bulk capacitors of my guitar amp. Here's a schematic of it: simulate this circuit – Schematic created using CircuitLab According to formula Vpp=I/fC, ...
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1 vote
1 answer
1k views

Guitar signal with opamp boost

Hi just having some issues understanding what's happening with my opamp circuit. Vin is a Sine wave at 1kHz and VG is 4.5V. From what I understand this circuit should boost the signal I provide it ...
0 votes
1 answer
131 views

Modifying guitar amp to run on batteries, switching between center tapped transformer and batteries with only DPDT switch

My situation is as follows: I'm trying to convert a small guitar amplifier to dual power. Mains and battery. The power supply that comes in the guitar amp is a center tapped 120V to 14V supply. After ...
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2 votes
2 answers
407 views

Thermal Management for Arcol HS50/HS100 50/100W Wirewound resistors

I'm designing a 100W dummy load for a guitar amplifier using Arcol HS50 and HS100 resistors. Here's a link to the datasheet: http://www.arcolresistors.com/wp-content/uploads/2014/03/HS-Datasheet.pdf ...
6 votes
2 answers
1k views

What is simpliest possible guitar active preamp design

I want to build guitar active preamp inside my bass guitar. It has 2 humbacker pickups (3.4kOhm DC resistance each) for 2 lower and for 2 upper strings, and i want to preamplify each with a separate ...
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0 votes
2 answers
2k views

Potentiometer with SPST Switch Wiring With Bypass

I'm stumped on wiring a 10K Ohm audio control potentiometer with spst switch into a LM386 amplifier circuit. The pot I'm using is very similar to the one in this link: https://www.radioshack.com/...
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0 votes
3 answers
2k views

Capacitor Value in Bass amplifier to speaker circuit

Replacing electrolytics in a 30+ year old Ampeg BT-15 bass amplifier. The PS filter caps are \$ 2500 \mu F/80V\$ which are rare to be found; I know that 3300/100 would be okay for the filter. There's ...
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3 votes
1 answer
2k views

Using Audio Jack Switches as Paralell/Series toggle? (guitar amp and cabinets)

I have a guitar amp that has one output that can handle either an 8 or 16 Ohm load. I have a cabinet with two 8 ohm speakers (each with a separate input). I could wire the speakers in series, and get ...
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4 votes
1 answer
565 views

Need help reading a schematic, is this a 220k log b pot?

This is saying a 220k log b potentiometer for the tone pot VR8, correct? That is such an extremely odd value, but I don't see that sort of notation very often either and I wanted to make sure I'm not ...
4 votes
3 answers
3k views

where to add gain and volume controls to LM386 guitar amp circuit?

Im trying to make a super simple guitar amp. heres the circuit using an LM386 operational amplifier: What exactly would affect gain but not volume, and volume but not gain? In the example circuit on ...
1 vote
1 answer
107 views

Sound amplification

A few months ago I built myself a cigarbox guitar. I built all myself, including the pickup and I have wired it with a volume potentiometer and a jack output. It works well but I have to use a pedal ...
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0 votes
1 answer
282 views

Schmitt Trigger configuration for enabling power from guitar pickup

I would like to enable power to a regulator from a 1Vpp guitar pickup. Threshold can be between 0.2V and 1V. And I need it to disable after about 60 seconds of no signal from the pickups. I'm ...
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