Vacuum Tube - KT77, JJ Electronics

Vacuum Tube - KT77, JJ Electronics

JJ Electronics
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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.

Apex Tube Matching
Matched versions of this tube use Apex Matching
SKU:
T-KT77-JJ
Item ID:
004874
Brand:
JJ Electronics, Apex Matched
Type:
RoHS Compliant
Part Numbers
Single or MatchedOur Part NumberUPC/EANJJ Electronics Part Number
Apex Matched PairT-KT77-JJ-MP609722123167
Apex Matched QuadT-KT77-JJ-MQ609722123174
SingleT-KT77-JJ609722123150 KT77
Product Measurements by Type
Body Height98 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 Diameter33.3 mm
Item Height112 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 Information
Packaging DimensionsApex Matched Pair versionT-KT77-JJ-MP4.8 in. × 3.3 in. × 1.6 in.
Apex Matched Quad versionT-KT77-JJ-MQ4.8 in. × 3.3 in. × 3.3 in.
Single versionT-KT77-JJ1.6 in. × 1.6 in. × 4.6 in.
Weight (Packaging)Apex Matched Pair versionT-KT77-JJ-MP0.268 lbs.
Apex Matched Quad versionT-KT77-JJ-MQ0.536 lbs.
Single versionT-KT77-JJ0.134 lbs.
Product Measurements by Item
T-KT77-JJ-MP - Apex Matched Pair versionBody Height98 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 Diameter33.3 mm
Item Height112 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 versionBody Height98 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 Diameter33.3 mm
Item Height112 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 versionBody Height98 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 Diameter33.3 mm
Item Height112 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

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Specifications, Files, and Documents

PDF: Specification Sheet Specification Sheet470.74 KB

Questions and Answers

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Asked by Anonymous on August 3rd, 2022.
BradWbr
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

5.00 out of 5 based on 5 reviews
Andy G - September 22nd, 2022
5 out of 5

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!

John McMurtry - November 27th, 2021
5 out of 5

Tubes arrived quickly, were as ordered and perform as expected.

Rick Snyder - June 8th, 2020
5 out of 5

Excellent sounding tubes. Great bottom end response.

Rodolfo James - January 8th, 2016
5 out of 5

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!

Wishbone - October 14th, 2015
5 out of 5

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