Detail 01
Matched quartet
All four tubes draw similar current, so the amp's push-pull pairs stay balanced and hum stays low.
Product detailSKU #1274034469322
Groove TubesGold Series GT-6L6-S Matched Power Tubes Medium (4-7 GT Rating) Quartet
Independent shopping perspective
The Korena take
A matched quartet of 6L6 power tubes for amps that take them, screened to a medium bias rating. For retubing a 4-power-tube amp.
Strong match
Who this is for
- Retubing a 4x6L6 amp that has gone dull or noisy
- Owners who want all four tubes matched from one source
- Amps where a mid-range bias current suits the circuit
Consider the trade-offs
When to look elsewhere
- Amps using EL34, 6V6, or other power tube types
- Anyone without bias tools or a tech to set it
- Players needing only one or two replacement tubes
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
Medium rating (4-7 on the GT scale)
Middle of Groove Tubes' bias range. Breaks up at a moderate volume rather than very early or very late.
Detail 03
6L6 type
The American power tube behind clean headroom and firm low end. Not interchangeable with EL34 without amp changes.
Detail 04
Set of four
Sized for amps with four power tube sockets. A two-tube amp only needs half of this.
Detail 05
Made in Slovakia
Current-production tube, not new-old-stock. Consistent supply, consistent construction.
Final check
Know before you order
- 01Power tubes need biasing after installation in most amps. Budget for a tech.
- 02Preamp tubes are not included. This is the power section only.
- 03Confirm your amp takes 6L6 and has four power tube sockets.
Product questions
Before you decide
Straight answers to the questions shoppers most often ask about this product.
01Do I have to rebias after installing these?
In most amps with adjustable bias, yes. The matched set makes it one adjustment instead of chasing mismatched tubes, but the bias still needs to be set for these specific tubes.
02What does the 4-7 rating mean?
It is Groove Tubes' own bias-current scale. Medium sits in the middle, so the amp breaks up at a moderate point rather than unusually early or late.
03Can I use these to replace EL34s?
No. 6L6 and EL34 have different requirements and are not a drop-in swap without amp modification.
04Can I install a quartet in a two-tube amp?
You would only use two of them, and you should keep a matched pair. Buying a quartet for a two-tube amp leaves you with spares.
Reference
Full specifications
The complete catalog record, organized around the decisions musicians make when comparing gear.
2 detailsBody & build
- Color
- Gold
- Country of Origin
- Slovakia
