Vacuum Tube - KT77, JJ Electronics
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Starting at: $26.95
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The JJ Electronic KT77 is a reproduction of the original tubes that captures the sound that made the KT77 famous. In their typical fashion, JJ has built this tube in a solid construction that is robust and highly reliable. This tube has more headroom than a typical EL34. The low end is fat and defines with detailed and responsive mids and smooth highs. This is an excellent tube for adding more power to the sound of an EL34 amp.
Matched versions of this tube use Apex Matching
RoHS Compliant
Accessory Items:
| Single or Matched | Our Part Number | UPC/EAN | JJ Electronics Part Number |
|---|---|---|---|
| Apex Matched Pair | T-KT77-JJ-MP | 609722123167 | |
| Apex Matched Quad | T-KT77-JJ-MQ | 609722123174 | |
| Single | T-KT77-JJ | 609722123150 | KT77 |
| Body Height | 98 mm | |
| Cathode Current (Ik) | ≤ 180 mA | |
| Filament Current (If) | 1.4 A | |
| Filament Voltage (Uf) | 6.3 V | |
| Gain (μ) | 11.5 | |
| Grid 1 voltage (Ug1) | -13.5 V typical | |
| Grid 2 current (Ig2) | ≤ 10 mA | |
| Grid 2 dissipation (Wg2) | 6 W | |
| Grid 2 voltage (Ug2) | ≤ 600 V, 250 V typical | |
| Grid capacitance (cg1) | 16.5 pF | |
| Grid to Plate Capacitance (ca/g) | 1 pF | |
| Internal Resistance (Ri) | 23 kΩ | |
| Item Diameter | 33.3 mm | |
| Item Height | 112 mm | |
| Plate Capacitance (ca) | 9 pF | |
| Plate Current (Ia) | 100 mA | |
| Plate Dissipation (Wa) | ≤ 25 W | |
| Plate Voltage (Ua) | ≤ 800 V, 250 V typical | |
| Transconductance (S) | 10.5 mA/V |
| Packaging Dimensions | Apex Matched Pair version | T-KT77-JJ-MP | 4.8 in. × 3.3 in. × 1.6 in. |
| Apex Matched Quad version | T-KT77-JJ-MQ | 4.8 in. × 3.3 in. × 3.3 in. | |
| Single version | T-KT77-JJ | 1.6 in. × 1.6 in. × 4.6 in. | |
| Weight (Packaging) | Apex Matched Pair version | T-KT77-JJ-MP | 0.268 lbs. |
| Apex Matched Quad version | T-KT77-JJ-MQ | 0.536 lbs. | |
| Single version | T-KT77-JJ | 0.134 lbs. |
| T-KT77-JJ-MP - Apex Matched Pair version | Body Height | 98 mm |
| Cathode Current (Ik) | ≤ 180 mA | |
| Filament Current (If) | 1.4 A | |
| Filament Voltage (Uf) | 6.3 V | |
| Gain (μ) | 11.5 | |
| Grid 1 voltage (Ug1) | -13.5 V typical | |
| Grid 2 current (Ig2) | ≤ 10 mA | |
| Grid 2 dissipation (Wg2) | 6 W | |
| Grid 2 voltage (Ug2) | ≤ 600 V, 250 V typical | |
| Grid capacitance (cg1) | 16.5 pF | |
| Grid to Plate Capacitance (ca/g) | 1 pF | |
| Internal Resistance (Ri) | 23 kΩ | |
| Item Diameter | 33.3 mm | |
| Item Height | 112 mm | |
| Plate Capacitance (ca) | 9 pF | |
| Plate Current (Ia) | 100 mA | |
| Plate Dissipation (Wa) | ≤ 25 W | |
| Plate Voltage (Ua) | ≤ 800 V, 250 V typical | |
| Transconductance (S) | 10.5 mA/V | |
| T-KT77-JJ-MQ - Apex Matched Quad version | Body Height | 98 mm |
| Cathode Current (Ik) | ≤ 180 mA | |
| Filament Current (If) | 1.4 A | |
| Filament Voltage (Uf) | 6.3 V | |
| Gain (μ) | 11.5 | |
| Grid 1 voltage (Ug1) | -13.5 V typical | |
| Grid 2 current (Ig2) | ≤ 10 mA | |
| Grid 2 dissipation (Wg2) | 6 W | |
| Grid 2 voltage (Ug2) | ≤ 600 V, 250 V typical | |
| Grid capacitance (cg1) | 16.5 pF | |
| Grid to Plate Capacitance (ca/g) | 1 pF | |
| Internal Resistance (Ri) | 23 kΩ | |
| Item Diameter | 33.3 mm | |
| Item Height | 112 mm | |
| Plate Capacitance (ca) | 9 pF | |
| Plate Current (Ia) | 100 mA | |
| Plate Dissipation (Wa) | ≤ 25 W | |
| Plate Voltage (Ua) | ≤ 800 V, 250 V typical | |
| Transconductance (S) | 10.5 mA/V | |
| T-KT77-JJ - Single version | Body Height | 98 mm |
| Cathode Current (Ik) | ≤ 180 mA | |
| Filament Current (If) | 1.4 A | |
| Filament Voltage (Uf) | 6.3 V | |
| Gain (μ) | 11.5 | |
| Grid 1 voltage (Ug1) | -13.5 V typical | |
| Grid 2 current (Ig2) | ≤ 10 mA | |
| Grid 2 dissipation (Wg2) | 6 W | |
| Grid 2 voltage (Ug2) | ≤ 600 V, 250 V typical | |
| Grid capacitance (cg1) | 16.5 pF | |
| Grid to Plate Capacitance (ca/g) | 1 pF | |
| Internal Resistance (Ri) | 23 kΩ | |
| Item Diameter | 33.3 mm | |
| Item Height | 112 mm | |
| Plate Capacitance (ca) | 9 pF | |
| Plate Current (Ia) | 100 mA | |
| Plate Dissipation (Wa) | ≤ 25 W | |
| Plate Voltage (Ua) | ≤ 800 V, 250 V typical | |
| Transconductance (S) | 10.5 mA/V |
 Specification Sheet | All Models |
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Questions and Answers
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1 answers
I have a VTL IT85 and am now using new production EL34's - the amp takes a quad. This amp originally came from the factory with KT77 - I don't know whether VTL used Genalex or JJ for those. I do know that VTL used JJ for all the small tubes.
Can you somehow describe the sound of these JJ KT77 as compared to the new production Mullard EL34 I'm now using?
Thanks very much.
Best wishes,
Paul
Asked by Anonymous on August 3rd, 2022.
August 3rd, 2022
Staff Member
The product description in the listing as well as numerous customer reviews all give first hand experiences of the perceived differences between KT77s and EL34s. Getting into finer detail than that is not possible as nuances in tone can be subjective.
Product Reviews
I recently purchased a matched pair of JJ kt77 Power tubes from antique electronics supply. The tubes were matched to the Apex system and I even got a personal phone call from them explaining to me that the numbers I sent in to match have now been updated into the new system come up and asked me if the relevant number would be acceptable. The technician explained that there were a couple options and one of them would have been more desirable than my original order so together we made a decision to change to a different matching number according to the Apex updated system. He also mentioned that after I got the tubes and try them if I wasn't happy that I could send them back for a replacement. When the tubes arrived I immediately installed them into an old Traynor yba1a guitar amplifier that I've been restoring and they sounded magnificent! I will now be ordering a second set!
Tubes arrived quickly, were as ordered and perform as expected.
Excellent sounding tubes. Great bottom end response.
I was a little skeptical about the difference from switching from el34s to kt77 and the tones I would get. After installation I was blown away! It was way beyond my expectations. Very saturated tone with a better low end. I couldn't be happier!
I put these in an Egnater renegade amp instead of the EL34"s and re-biased. Very clean with some upper end "jingle" that I did not have with the other tubes. Slightly more gain than the 6L6's and a little brighter. The tube matching with the new Apex system was dead on. Thanks again!!wb