Detail 01
Matched duet
Both tubes draw close to the same current, so the output stage stays balanced and bias sits right for both.
Product detailSKU #1274319722331
MESA/BoogieEL-34 STR 447 Power Tubes - Matched Duet Duet
Independent shopping perspective
The Korena take
Matched pair of EL-34 power tubes screened by MESA to their STR-447 spec. For retubing a Mesa amp that runs EL-34s.
Strong match
Who this is for
- Retubing a two-power-tube EL-34 amp head or combo
- Mesa owners who want a factory-screened replacement
- Replacing one worn or failed power tube pair
Consider the trade-offs
When to look elsewhere
- Amps running four or six power tubes — one duet won't fill them
- Amps built around 6L6, EL84 or KT88 tubes
- Anyone needing a preamp tube — these are power section only
What matters in use
The specifications, translated
Catalog numbers tell only part of the story. These are the details most likely to change how this product feels, sounds, or fits into a setup.
Detail 02
EL-34
British-leaning power tube. Earlier breakup and a midrange push compared with the tighter, cleaner 6L6.
Detail 03
STR-447
MESA's own screening spec. Tubes are tested and sorted before they ship rather than pulled off a general production run.
Detail 04
Two tubes per set
Covers an amp with a two-tube output section. Four-tube amps need two duets, and they should be matched to each other.
Final check
Know before you order
- 01Power tubes need a bias check after installation unless your amp is fixed-bias by design
- 02Confirm your amp is wired for EL-34 — swapping tube types is not always drop-in
- 03Tubes only. No sockets, retaining clips or bias tools included
Product questions
Before you decide
Straight answers to the questions shoppers most often ask about this product.
01Do I need to rebias after installing these?
Assume yes. Even matched tubes vary from the set they replace, and running the wrong bias shortens tube life or dulls the amp. Check the bias unless your amp is self-biasing.
02Can I put these in an amp that came with 6L6 tubes?
Not automatically. Some amps have a switch or are designed for both, many are not. Check your amp's documentation before swapping tube types.
03My amp has four power tubes. Can I buy two of these?
You can, but the two duets should also be matched to each other. Buying a matched quad is the cleaner route for a four-tube amp.
04Should I replace power tubes in pairs?
Yes. Replacing a single tube leaves a mismatch in the output stage. Always swap the full matched set.
Reference
Full specifications
The complete catalog record, organized around the decisions musicians make when comparing gear.
1 detailsBody & build
- Color
- Matched Duet Duet
