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Questions tagged [guitar-amplifier]

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Can an audio isolation transformer between a preamplifier and an amplifier cause the amplifier's fuse to blow? [closed]

I'm building a microphone preamplifier. I was having problems with hum (intermittent ground hum when touching the case) and decided to try adding an audio isolation transformer (600 ohm : 600 ohm) ...
steev's user avatar
  • 111
1 vote
2 answers
75 views

Is the reason for guitar "tone suck", i.e. loss of high end frequencies with impedance mismatching, actually due to high reactance?

When connecting a guitar's output to an input with insufficiently high input impedance, the signal is undesirably filtered, which is referred to as "tone suck". To deal with this, it is ...
interoception's user avatar
0 votes
3 answers
239 views

DIY guitar amp cabinet selector switch

Problem statement: I have 2 guitar amplifiers and I have 2 speaker cabinets that normally connect via speaker cables (1/4" connectors). I would like to create a passive device that lets me ...
Luther Baker's user avatar
0 votes
2 answers
83 views

Replace One Centre-Tapped Resistor with Two Resistors

I have just started research and design on a small tube guitar amp and have hit the first of what is probably many uncertainties. The idea is to reuse the transformers, 7C5 power tube and 7Y4 ...
slubtle's user avatar
0 votes
1 answer
62 views

Switch to handle two inputs and switch between two sets of two outputs (guitar amp send and return switch)

I am looking to build a simple box, for fun, to switch the send and return signals from a guitar amplifier effects loop between two different amplifiers, depending on which amp I am using at the time. ...
jlbriggs's user avatar
  • 103
6 votes
3 answers
2k views

Why am I getting heavy output distortion from a BJT amplifier when driving an 8 ohm load?

Hello electronics professionals and enthusiasts! Software engineer mingling with breadboards and discrete components in his spare time here. I'm trying to build a simple BJT amplifier for my electric ...
Alex's user avatar
  • 71
0 votes
2 answers
219 views

Power supply transformer replacement

First of all I apologize, I am not an electronics expert, just fairly good at it, but now I am faced with this weird problem that I can't figure out. I needed to replace a transformer on a power ...
Zen Max's user avatar
  • 13
0 votes
2 answers
256 views

I need help setting up a guitar speaker jack plate

I have a 1x12 wedge cabinet I'm repurposing into a guitar speaker cab. It has a jack plate with two 1/4" mono jacks. What I'd like to do is reset the jack plate in such a way that it can: Run ...
kkitchen63's user avatar
0 votes
1 answer
71 views

replace 220v transformer into a 110v transformer with same specs [closed]

I am trying to convert my European 220V VOX AD50VT guitar amplifier into 110V to use it in the USA. I plugged it to 110V and it does not work, there's just the master light that comes up but it ...
user avatar
3 votes
4 answers
3k views

Guitar amp is making bad noise when I plug in a jack only

When I plug in my guitar cable by itself in the amp (without the guitar attached) it makes a bad noise. I changed the cables and the noise is still there in the amp. Also, when I plugged just the jack ...
Basheer's user avatar
  • 159
2 votes
1 answer
106 views

Midpoint Adjustment on Complimentary BJT Amplifier

Looking at this whoknowswhat 100w amplifier on eBay. There are two trim pots, one is for bias current, and the other for "midpoint" adjustment. The schematic supplied does not show the ...
ITPhoenix's user avatar
  • 145
2 votes
3 answers
390 views

Guitar amplifier emits a continuous beep, which pitch vary depending on "bass" and "gain" knobs. Finding what's wrong in the circuit

I have an old transistor (EDIT: not transistor, but OP, from comments) guitar amp, a Laney Session 45 Reverb. I couldn't find any schematics online unfortunately, it doesn't seem to be a very popular ...
C. Crt's user avatar
  • 121
2 votes
2 answers
148 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 ...
user1847129's user avatar
4 votes
2 answers
1k 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 ...
Daniel Oren-Ibarra's user avatar
-2 votes
2 answers
108 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 ...
Daniel Oren-Ibarra's user avatar
0 votes
1 answer
466 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 ...
Island's user avatar
  • 9
2 votes
4 answers
846 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 ...
Daniel Oren-Ibarra's user avatar
1 vote
4 answers
754 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 ...
p-we's user avatar
  • 55
0 votes
2 answers
288 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 ...
user avatar
1 vote
1 answer
125 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 ...
Aaron R.'s user avatar
0 votes
3 answers
341 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 ...
user3209815's user avatar
0 votes
1 answer
681 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 ...
tsalcet's user avatar
-1 votes
1 answer
791 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 ...
Steve's user avatar
  • 80
0 votes
1 answer
750 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 ...
J K's user avatar
  • 167
0 votes
1 answer
194 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 ...
user11779's user avatar
1 vote
1 answer
193 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, ...
Steve's user avatar
  • 80
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 ...
markv12's user avatar
  • 249
1 vote
1 answer
244 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 ...
Jacob Lara's user avatar
0 votes
0 answers
59 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 ...
haydnwarne's user avatar
1 vote
1 answer
272 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 ...
Piotr Tyburski's user avatar
1 vote
3 answers
425 views

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

I have a Fender Frontman 25R and I would like to use the reverb send and return as an effect loop instead. I don't mind getting rid of the reverb tank of the amp. So I found the schematic of the amp ...
Nicolas's user avatar
  • 11
0 votes
3 answers
492 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 ...
ChronoLogic's user avatar
1 vote
2 answers
389 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 ...
Green_spleen's user avatar
0 votes
1 answer
48 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 ...
SelfStudent's user avatar
1 vote
2 answers
607 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 ...
Rob Lewis's user avatar
  • 299
3 votes
1 answer
531 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 ...
Ryan Jaquin's user avatar
3 votes
1 answer
877 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: ...
andowt's user avatar
  • 1,008
6 votes
2 answers
2k 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. ...
Avid Pro Tool's user avatar
12 votes
7 answers
13k 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 ...
Willis Blackburn's user avatar
1 vote
3 answers
187 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 ...
Marco Castro's user avatar
1 vote
0 answers
230 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 ...
ForeverLearningJP's user avatar
0 votes
1 answer
245 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. ...
netanalyzer's user avatar
1 vote
2 answers
119 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 ...
Gen Ts's user avatar
  • 113
0 votes
2 answers
361 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 ...
Jeremiah Rose's user avatar
0 votes
1 answer
141 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 ...
user2276280's user avatar
1 vote
1 answer
2k 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...
xakepp35's user avatar
  • 415
1 vote
0 answers
119 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 ...
akki2401's user avatar
4 votes
2 answers
515 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/...
user avatar
3 votes
3 answers
611 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-...
sean read's user avatar
  • 133
1 vote
0 answers
247 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, ...
Qeeet's user avatar
  • 319