Vacuum Tube - KT88, JJ Electronics
The JJ Electronic KT88 is a sonically faithful reproduction of the original tubes with a robust construction encased in a thick glass envelope. The JJ KT88 delivers a powerful 42 Watts with plenty of headroom to spare. This tube has a tone that is warm and lively with a detailed and balance response. The JJ KT88 is an excellent choice for Hi-Fi stereo equipment as well as guitar amplifiers. It can be used in place of 6550 tubes.
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-KT88-JJ-MP | 609722123235 | |
| Apex Matched Quad | T-KT88-JJ-MQ | 609722123242 | |
| Apex Matched Sextet | T-KT88-JJ-MS | 609722123259 | |
| Single | T-KT88-JJ | 609722123228 | KT88 |
| Body Height | 110 mm | |
| Cathode Current (Ik) | ≤ 230 mA | |
| Filament Current (If) | 1.6 A | |
| Filament Voltage (Uf) | 6.3 V | |
| Gain (μ) | 8 | |
| Grid 1 voltage (Ug1) | -15 V typical | |
| Grid 2 current (Ig2) | ≤ 7 mA | |
| Grid 2 dissipation (Wg2) | 8 W | |
| Grid 2 voltage (Ug2) | ≤ 600 V, 250 V typical | |
| Grid capacitance (cg1) | 16.5 pF | |
| Grid to Plate Capacitance (ca/g) | 2.3 pF | |
| Internal Resistance (Ri) | 12 kΩ | |
| Item Diameter | 52 mm | |
| Item Height | 125 mm | |
| Plate Capacitance (ca) | 10 pF | |
| Plate Current (Ia) | 140 mA | |
| Plate Dissipation (Wa) | ≤ 42 W | |
| Plate Voltage (Ua) | ≤ 800 V, 250 V typical | |
| Transconductance (S) | 11.5 mA/V |
| Packaging Dimensions | Apex Matched Pair version | T-KT88-JJ-MP | 5.3 in. × 4.5 in. × 2.3 in. |
| Apex Matched Quad version | T-KT88-JJ-MQ | 5.3 in. × 4.5 in. × 4.5 in. | |
| Apex Matched Sextet version | T-KT88-JJ-MS | 6.8 in. × 5.3 in. × 4.5 in. | |
| Single version | T-KT88-JJ | 2.3 in. × 2.3 in. × 5.1 in. | |
| Weight (Packaging) | Apex Matched Pair version | T-KT88-JJ-MP | 0.54 lbs. |
| Apex Matched Quad version | T-KT88-JJ-MQ | 1.08 lbs. | |
| Apex Matched Sextet version | T-KT88-JJ-MS | 1.62 lbs. | |
| Single version | T-KT88-JJ | 0.27 lbs. |
| T-KT88-JJ-MP - Apex Matched Pair version | Body Height | 110 mm |
| Cathode Current (Ik) | ≤ 230 mA | |
| Filament Current (If) | 1.6 A | |
| Filament Voltage (Uf) | 6.3 V | |
| Gain (μ) | 8 | |
| Grid 1 voltage (Ug1) | -15 V typical | |
| Grid 2 current (Ig2) | ≤ 7 mA | |
| Grid 2 dissipation (Wg2) | 8 W | |
| Grid 2 voltage (Ug2) | ≤ 600 V, 250 V typical | |
| Grid capacitance (cg1) | 16.5 pF | |
| Grid to Plate Capacitance (ca/g) | 2.3 pF | |
| Internal Resistance (Ri) | 12 kΩ | |
| Item Diameter | 52 mm | |
| Item Height | 125 mm | |
| Plate Capacitance (ca) | 10 pF | |
| Plate Current (Ia) | 140 mA | |
| Plate Dissipation (Wa) | ≤ 42 W | |
| Plate Voltage (Ua) | ≤ 800 V, 250 V typical | |
| Transconductance (S) | 11.5 mA/V | |
| T-KT88-JJ-MQ - Apex Matched Quad version | Body Height | 110 mm |
| Cathode Current (Ik) | ≤ 230 mA | |
| Filament Current (If) | 1.6 A | |
| Filament Voltage (Uf) | 6.3 V | |
| Gain (μ) | 8 | |
| Grid 1 voltage (Ug1) | -15 V typical | |
| Grid 2 current (Ig2) | ≤ 7 mA | |
| Grid 2 dissipation (Wg2) | 8 W | |
| Grid 2 voltage (Ug2) | ≤ 600 V, 250 V typical | |
| Grid capacitance (cg1) | 16.5 pF | |
| Grid to Plate Capacitance (ca/g) | 2.3 pF | |
| Internal Resistance (Ri) | 12 kΩ | |
| Item Diameter | 52 mm | |
| Item Height | 125 mm | |
| Plate Capacitance (ca) | 10 pF | |
| Plate Current (Ia) | 140 mA | |
| Plate Dissipation (Wa) | ≤ 42 W | |
| Plate Voltage (Ua) | ≤ 800 V, 250 V typical | |
| Transconductance (S) | 11.5 mA/V | |
| T-KT88-JJ-MS - Apex Matched Sextet version | Body Height | 110 mm |
| Cathode Current (Ik) | ≤ 230 mA | |
| Filament Current (If) | 1.6 A | |
| Filament Voltage (Uf) | 6.3 V | |
| Gain (μ) | 8 | |
| Grid 1 voltage (Ug1) | -15 V typical | |
| Grid 2 current (Ig2) | ≤ 7 mA | |
| Grid 2 dissipation (Wg2) | 8 W | |
| Grid 2 voltage (Ug2) | ≤ 600 V, 250 V typical | |
| Grid capacitance (cg1) | 16.5 pF | |
| Grid to Plate Capacitance (ca/g) | 2.3 pF | |
| Internal Resistance (Ri) | 12 kΩ | |
| Item Diameter | 52 mm | |
| Item Height | 125 mm | |
| Plate Capacitance (ca) | 10 pF | |
| Plate Current (Ia) | 140 mA | |
| Plate Dissipation (Wa) | ≤ 42 W | |
| Plate Voltage (Ua) | ≤ 800 V, 250 V typical | |
| Transconductance (S) | 11.5 mA/V | |
| T-KT88-JJ - Single version | Body Height | 110 mm |
| Cathode Current (Ik) | ≤ 230 mA | |
| Filament Current (If) | 1.6 A | |
| Filament Voltage (Uf) | 6.3 V | |
| Gain (μ) | 8 | |
| Grid 1 voltage (Ug1) | -15 V typical | |
| Grid 2 current (Ig2) | ≤ 7 mA | |
| Grid 2 dissipation (Wg2) | 8 W | |
| Grid 2 voltage (Ug2) | ≤ 600 V, 250 V typical | |
| Grid capacitance (cg1) | 16.5 pF | |
| Grid to Plate Capacitance (ca/g) | 2.3 pF | |
| Internal Resistance (Ri) | 12 kΩ | |
| Item Diameter | 52 mm | |
| Item Height | 125 mm | |
| Plate Capacitance (ca) | 10 pF | |
| Plate Current (Ia) | 140 mA | |
| Plate Dissipation (Wa) | ≤ 42 W | |
| Plate Voltage (Ua) | ≤ 800 V, 250 V typical | |
| Transconductance (S) | 11.5 mA/V |
 Specification Sheet | All Models |
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Specifications, Files, and Documents
Questions and Answers
Click each question to see its answers.
1 answers
I am using 6550a tubes in a ham radio modulator can I use these KT88 tubes to replace the 6550A tubes and if so will I squeak a bit more power out of these???
Asked by Anonymous on May 21st, 2016.
May 23rd, 2016
Staff MemberTop Contributor
The KT88's are similar in construction and power to the 6550's but they may not be drop in replacements depending on the unit. I would suggest referencing the spec sheet for both found on the product pages for absolute compatibility.
1 answers
el34 is too treble oriented in my bivalve 30 thd/orange cab set up. I want to get more balanced. needs more low end. I was thinking kt77 or kt88. Your opinions and suggestions are needed as I am new at this. I always bought combos now I am trying to shape my sound.
Asked by Anonymous on May 26th, 2017.
May 26th, 2017
Staff Member
The KT 77 and 88 will give you more lows but not necessarily less highs. Our experience has been that swapping preamp tubes has more of an effect on the high end than the power tubes. Also, if you have an older bivalve the KT88's will be to big for the top to fit.
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Product Reviews
I inserted them in the sockets of my Sunn 200S adjusted the bias and the amp is alive.
Brought a much warmer sound to the entire frequency range in my Willsenton R8. A must have upgrade to this amplifier. Great value from a great vendor that appreciates their customers and is focused on customer service. Thanks.
I've been using J/J tubes since they first became available. I use them in my own gear and the gear I service. Only 2 tubes had to be replaced in all that time. They work well and can take the abuse of guitar amplifiers on the road.
Quick delivery and great tubes.
Thank you.
These are great tubes for my Leslie 122. Great sound, nice drive. Works as a modern replacement for these amps.
I have heard about the kt88,but I never tried them. So I brought these tubes and man I never go back to the 6550 power amp tubes.gives you all the lows you need. I use them in my 122 Leslie speaker,
Lovely tubes. Solid construction. Typical KT88 sound, as it should be.
I've tried more than a dozen power tubes in my Amps &* Sound Mogwai headphone/speaker amplifier. I checked out a variety of KT88, 6L6, 6CA7, 6550, 5881, and similar tubes.
The JJ KT88 are excellent tubes. They have great bass, smooth treble, and very nice full mids.
Unlike most KT88 tubes, they have virtually no microphonics at all.
The sound, availability, price, ability to get Apex-matched tubes, and robust build quality pushed me to make this my house tube.
Other tubes I put them up against:
Mullard KT88 (New and NOS)
Svetlana 6550 Winged C (New and NOS)
6P3S (NOS)
Svetlana 6550 (New)
Preferred Series KT88 (New)
JJ 6CA7 (New)
Sovtek 5881WGC (New)
5881 Tung-Sol (New)
Tung-Sol 6L6GC-STR (New)
Electro-Harmonix KT88 (New)
Electro-Harmonix EL34 (New)
Electro-Harmonix 6550 (New)
As far as I can tell, these tubes are visually and sonically identical to the OEM branded KT88s that came in my McIntosh MC275mkVI. I tried to replace them with the Russian Gold Lion reissues and much prefer the JJs in this amp. The Gold Lions were crispier and tighter, but thinner sounding and too aggressive in the high mids and low treble. The JJs are easier on the ears. The bass is especially nice.
These tube, related to the build, are massive, strong,heavy.
On My Chinese amp (Yaqin MS110 b) sounds a bit less "tube" than the Chinese one, more "KSSSSS".
After adjusting the bias, at 0.5 V, that was the bias of shuguang tubes, these ones let the amp drastically less hot...
Before, with shuguang tubes my amps was difficult to touch after an hour, now with these tubes, after two hours, transformers are just more than tempered...