What to check before buying a used amp: a simple risk guide

Got a great-looking amp and a small voice in your head saying "hold up"? That gut feeling often saves you money. You can spot the easy wins and the hidden costs with a few quick checks.

Low-risk buys: cheap practice amps and small combos

These are small, lightweight amps meant for practice. They rarely hide big problems. Look for clean cabinet edges, steady knobs, and a working power light. Plug in a clean guitar cable and play for five minutes at different volumes. Listen for steady sound, not crackles or sudden drops.

Check the power cable for frays and a tight plug. Make sure the speaker cone moves when you play (a gentle push with a finger will show movement). If the amp has built-in effects, try a couple and see if they sound right. If everything works and the price is low, you likely have a low-risk buy.

Medium-risk buys: tube amps, vintage combos, and expensive used gear

These amps can sound great but hide higher repair costs. Tube amps need more care. Ask if the seller recently replaced tubes. Look for even, soft glow in glass tubes when the amp is on. If a tube flashes or is dull, it may need replacing. Smell the amp: a sharp burnt odor can mean past overheating.

Inspect jacks and switches. Wiggle the input, output, and footswitch jacks while playing to see if noise appears. Check bias notes or service stickers that show recent maintenance. If the amp is old, ask about the speaker brand and age; old speakers can be costly to replace.

Negotiation levers:

• Point out any crackles, hum, or sticky knobs to lower the price

• Offer to buy with a new set of tubes if a tube amp needs them

• Ask for a short trial period or to test with your guitar

• Suggest a price hold while you factor in speaker or plate repair costs

• Request original footswitches or covers as part of the deal

• Note any missing screws, covers, or cosmetic damage when bargaining

High-risk buys: rare vintage pieces, amps with electrical work, and gear sold as-is

These have the biggest upside and the biggest cost risk. If the amp has non-original wiring, large dents, or a history of intermittent faults, plan for a service visit. Heavy transformers and old components can make repairs expensive. If the seller says "it works sometimes" or brands it "as-is", treat the price as negotiable and the risk as high.

Micro-moment: You meet a seller at a coffee shop and bring a cable. You plug in, play a couple of chords, and everything sounds fine. Then the amp heats up and a hum starts after ten minutes. That hum is a real clue. Walk away unless the price drops to cover a shop check.

Quick hands-on tests you can do in minutes

Start with the basics: power on and off, volume sweep, and tone sweep. Try every input, output, and channel. Tap the speaker cone gently to feel for rattles. Switch between clean and driven channels while listening for sudden jumps in level or noise. If it’s a tube amp, let it warm up and listen for odd noises after five to ten minutes.

If you have a multimeter and know how to use it, check the fuse and power supply voltages. Don’t open the amp chassis unless you know high-voltage safety. A quick visual check of the inside (with power off and unplugged) can show obvious bad caps (bulging or leaking) and sloppy wiring.

Bottom line: price bands and what to expect

Low price band: under a few hundred. Expect cosmetic wear but low repair cost. Buy if it sounds right and knobs move cleanly.

Medium price band: a few hundred to mid-range. Expect some service history. Pay less for unknown tube age or worn speakers. Use the negotiation levers above.

High price band: vintage and boutique. Only buy if you can verify service, or you have budgeted a shop check and possible repairs.

If it won’t stay in tune through a short play test, assume there’s a reason and negotiate from that risk.

Today’s takeaway: Test every input, listen for changes as the amp warms, and use small faults as bargaining tools to lower the price.