What to check before you buy a used amp: a practical checklist
- Mark Kurkdjian
- Jan 15
- 3 min read
A bad amp can sound fine in a store and die in your living room. One quick check now can save you a trip to the shop and a pile of frustration.
What to look for at a glance
Look the amp over like a buyer with a flashlight. Check the case for dents and rust. Look for fresh screws or mismatched paint — signs it was opened or repaired. Check the input and speaker jacks for bent metal or loose sockets. If it has tubes, look for dark or cloudy glass; that can mean old tubes or poor use.
Power and basic sound test
Bring a cable and a guitar (or keyboard) if you can. Plug in and turn knobs slowly. The amp should power on cleanly with no popping, grinding, or smoke smell. Let it warm up for a few minutes. Play at low and medium volumes. Listen for hum, buzz, or crackle that changes with volume.
Plug in one instrument and one cable you know work.
Test every channel and any drive or boost switches.
Turn reverb/FX on and off and listen for noise.
Tap the amp gently; loose parts sometimes rattle.
If it has a fan, listen for uneven or loud motor sounds.
Check speaker output by listening for clear, full tone.
Electronics, tubes, and connectivity
If the amp is solid-state, ask about service history. For tube amps, count tubes and ask how old they are. Tubes wear out; replacements cost money. If you hear intermittent cuts or volume drops, that points to connections or failing tubes. Try plugging headphones if there is an output; weird tones there can show preamp issues. Check any footswitch jacks by wiggling a plug gently while sound is on — this can reveal bad jacks or brittle wiring.
Micro-moment: You meet the seller at a cafe to try the amp. You bring your own cable and a small pedal. You test the amp on battery power if available, then with mains. This quick setup shows whether the amp behaves the same in two places.
Speaker and cabinet checks
Look and listen to the speaker cones. Small tears or creases can cause buzzing at higher volumes. Put one finger on the center of the cone and strum a chord gently; you should feel even movement, not scraping or grinding. Smell inside the grill; a musty or burnt smell can signal past electrical trouble. If the amp is combo-style (amp and speaker in one box), ask to hear it with a low and a medium load to test the speaker under stress.
Paperwork, serials, and price negotiation
Ask for the serial number and any service receipts. A maintenance record is a plus. Check how long the seller has owned it and why they are selling. Use visible wear and any needed parts as real negotiation points. If tubes need replacement or the speaker has damage, deduct those costs from the asking price. Be ready to walk away if the amp makes strange noises or the seller refuses a basic trial.
Red flags and final checklist
Red flags to watch for: intermittent sound, heavy rust, melted plastic, strong chemical or burned smells, and signs the amp was opened with parts missing. If the amp is priced unusually low with poor answers about its history, assume more work is needed.
Today’s quick checklist before you buy: bring a cable and instrument; power the amp and let it warm; test every control and channel; listen for hum/crackle at different volumes; inspect tubes, speaker, and jacks; ask for service records and the serial number.
A straight neck and even frets matter more than shiny hardware — price the setup before you fall for the look.
Today’s takeaway: A few hands-on tests and a clear checklist will save you time and money when buying a used amp.
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