Vacuum Tube - EL84, Tube Amp Doctor
Tube Amp Doctor opted for the thickest glass possible and the heaviest construction available, just like the Russian EL84M, and combined these features with the sonically most promising cathode plate options, in order to meet and exceed the tonal quality of the EL84-Cz. Finally, Tube Amp Doctor added the gold grid wire in order to improve overall reliability. The sound can be described as very harmonic in the middle and treble frequencies, without adding too much power to the bass. The result is the best EL84 in current production.
No Compromise!
Q: When does a power tube become a Premium Selected power tube?
A: All power tubes labeled Premium Selected have passed the following tests:
- Plate Current (PC) and Amplification (TC)
- Low Noise Test
- Microphonic Test
- Sonic Tests
- Shock Tests
- Listening Tests
- Shorts & Leakage Tests
| Single or Matched | Our Part Number | UPC/EAN | Tube Amp Doctor Part Number |
|---|---|---|---|
| Matched Pair | T-EL84-TAD-MP | 609722123457 | |
| Matched Quad | T-EL84-TAD-MQ | 609722123464 | |
| Single | T-EL84-TAD | 609722123440 | RT871 |
| Body Height | 71 mm | |
| Cathode to Heater Voltage | ≤ 100 V | |
| D.C. Cathode Current, AF Power Amplifier | 65 mA | |
| D.C. Plate Voltage, AF Power Amplifier | 420 V | |
| Grid 1 (control) Voltage, Af Power Amplifier | -100 V | |
| Grid 1 Control Voltage, Class A1 | -4.8 V | |
| Grid 1 to Cathode, Grid 3, Grid 2, Base Sleeve, Heater Capacitance | < 10.8 pF | |
| Grid 1 to Plate Capacitance | < 0.5 pF | |
| Grid 2 Dc (screen) Dissipation, Af Power Amplifier | 2 W | |
| Grid 2 Dc (screen) Voltage, Af Power Amplifier | 300 V | |
| Grid 2 Screen Voltage, Class A1 | 250 V | |
| Heater Current | 0.76 A | |
| Heater Voltage | 5.8 V - 6.8 V, 6.3 V nominal | |
| Item Diameter | 22.5 mm | |
| Item Height | 77 mm | |
| Load Resistance, Class A1 | 5.2 kΩ | |
| Output Power (POut) @ 5% Distortion, Class A1 | 5.7 W | |
| Peak AF Grid 1 Control Voltage, Class A1 | 14 V | |
| Plate Dissipation, AF power amplifier (Wa) | 12 W | |
| Plate Voltage, class A1 (Ua) | 250 V | |
| Plate to Cathode, Grid 3, Grid 2, Base Sleeve, Heater Capacitance | < 6.5 pF | |
| Signal Plate Current, Class A1, maximum | 80 mA | |
| Transconductance, Class A1 (S) | 9 mA/V | |
| Zero Signal Grid 2 Screen Current, Class A1 | 10.8 mA | |
| Zero Signal Plate Current, Class A1 | 49.5 mA |
| Packaging Dimensions | Matched Pair version | T-EL84-TAD-MP | 1 in. × 2 in. × 3.3 in. |
| Matched Quad version | T-EL84-TAD-MQ | 1 in. × 4 in. × 3.3 in. | |
| Single version | T-EL84-TAD | 3.25 in. × 1 in. × 1 in. | |
| Weight (Packaging) | Matched Pair version | T-EL84-TAD-MP | 0.1 lbs. |
| Matched Quad version | T-EL84-TAD-MQ | 0.2 lbs. | |
| Single version | T-EL84-TAD | 0.05 lbs. |
| T-EL84-TAD - Single version | Body Height | 71 mm |
| Cathode to Heater Voltage | ≤ 100 V | |
| D.C. Cathode Current, AF Power Amplifier | 65 mA | |
| D.C. Plate Voltage, AF Power Amplifier | 420 V | |
| Grid 1 (control) Voltage, Af Power Amplifier | -100 V | |
| Grid 1 Control Voltage, Class A1 | -4.8 V | |
| Grid 1 to Cathode, Grid 3, Grid 2, Base Sleeve, Heater Capacitance | < 10.8 pF | |
| Grid 1 to Plate Capacitance | < 0.5 pF | |
| Grid 2 Dc (screen) Dissipation, Af Power Amplifier | 2 W | |
| Grid 2 Dc (screen) Voltage, Af Power Amplifier | 300 V | |
| Grid 2 Screen Voltage, Class A1 | 250 V | |
| Heater Current | 0.76 A | |
| Heater Voltage | 5.8 V - 6.8 V, 6.3 V nominal | |
| Item Diameter | 22.5 mm | |
| Item Height | 77 mm | |
| Load Resistance, Class A1 | 5.2 kΩ | |
| Output Power (POut) @ 5% Distortion, Class A1 | 5.7 W | |
| Peak AF Grid 1 Control Voltage, Class A1 | 14 V | |
| Plate Dissipation, AF power amplifier (Wa) | 12 W | |
| Plate Voltage, class A1 (Ua) | 250 V | |
| Plate to Cathode, Grid 3, Grid 2, Base Sleeve, Heater Capacitance | < 6.5 pF | |
| Signal Plate Current, Class A1, maximum | 80 mA | |
| Transconductance, Class A1 (S) | 9 mA/V | |
| Zero Signal Grid 2 Screen Current, Class A1 | 10.8 mA | |
| Zero Signal Plate Current, Class A1 | 49.5 mA | |
| T-EL84-TAD-MP - Matched Pair version | Body Height | 71 mm |
| Cathode to Heater Voltage | ≤ 100 V | |
| D.C. Cathode Current, AF Power Amplifier | 65 mA | |
| D.C. Plate Voltage, AF Power Amplifier | 420 V | |
| Grid 1 (control) Voltage, Af Power Amplifier | -100 V | |
| Grid 1 Control Voltage, Class A1 | -4.8 V | |
| Grid 1 to Cathode, Grid 3, Grid 2, Base Sleeve, Heater Capacitance | < 10.8 pF | |
| Grid 1 to Plate Capacitance | < 0.5 pF | |
| Grid 2 Dc (screen) Dissipation, Af Power Amplifier | 2 W | |
| Grid 2 Dc (screen) Voltage, Af Power Amplifier | 300 V | |
| Grid 2 Screen Voltage, Class A1 | 250 V | |
| Heater Current | 0.76 A | |
| Heater Voltage | 5.8 V - 6.8 V, 6.3 V nominal | |
| Item Diameter | 22.5 mm | |
| Item Height | 77 mm | |
| Load Resistance, Class A1 | 5.2 kΩ | |
| Output Power (POut) @ 5% Distortion, Class A1 | 5.7 W | |
| Peak AF Grid 1 Control Voltage, Class A1 | 14 V | |
| Plate Dissipation, AF power amplifier (Wa) | 12 W | |
| Plate Voltage, class A1 (Ua) | 250 V | |
| Plate to Cathode, Grid 3, Grid 2, Base Sleeve, Heater Capacitance | < 6.5 pF | |
| Signal Plate Current, Class A1, maximum | 80 mA | |
| Transconductance, Class A1 (S) | 9 mA/V | |
| Zero Signal Grid 2 Screen Current, Class A1 | 10.8 mA | |
| Zero Signal Plate Current, Class A1 | 49.5 mA | |
| T-EL84-TAD-MQ - Matched Quad version | Body Height | 71 mm |
| Cathode to Heater Voltage | ≤ 100 V | |
| D.C. Cathode Current, AF Power Amplifier | 65 mA | |
| D.C. Plate Voltage, AF Power Amplifier | 420 V | |
| Grid 1 (control) Voltage, Af Power Amplifier | -100 V | |
| Grid 1 Control Voltage, Class A1 | -4.8 V | |
| Grid 1 to Cathode, Grid 3, Grid 2, Base Sleeve, Heater Capacitance | < 10.8 pF | |
| Grid 1 to Plate Capacitance | < 0.5 pF | |
| Grid 2 Dc (screen) Dissipation, Af Power Amplifier | 2 W | |
| Grid 2 Dc (screen) Voltage, Af Power Amplifier | 300 V | |
| Grid 2 Screen Voltage, Class A1 | 250 V | |
| Heater Current | 0.76 A | |
| Heater Voltage | 5.8 V - 6.8 V, 6.3 V nominal | |
| Item Diameter | 22.5 mm | |
| Item Height | 77 mm | |
| Load Resistance, Class A1 | 5.2 kΩ | |
| Output Power (POut) @ 5% Distortion, Class A1 | 5.7 W | |
| Peak AF Grid 1 Control Voltage, Class A1 | 14 V | |
| Plate Dissipation, AF power amplifier (Wa) | 12 W | |
| Plate Voltage, class A1 (Ua) | 250 V | |
| Plate to Cathode, Grid 3, Grid 2, Base Sleeve, Heater Capacitance | < 6.5 pF | |
| Signal Plate Current, Class A1, maximum | 80 mA | |
| Transconductance, Class A1 (S) | 9 mA/V | |
| Zero Signal Grid 2 Screen Current, Class A1 | 10.8 mA | |
| Zero Signal Plate Current, Class A1 | 49.5 mA |
 Specification Sheet | All Models |
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Specifications, Files, and Documents
Questions and Answers
Click each question to see its answers.
1 answers
Where is the tube made?
Asked by Anonymous on February 10th, 2019.
February 11th, 2019
Staff Member
These tubes are made in China, then sent to Germany for thorough testing.
1 answers
Are you currently shipping to Australia as I am interested in buying some tubes
Asked by Anonymous on May 29th, 2020.
June 1st, 2020
Staff Member
We are indeed shipping internationally, yes.
Substitute Products
The following items can be substituted for this product. While not necessarily exactly the same, they will function as replacement items in your project.
Product Reviews
I really like these tubes so far in my studio guitar amp. They seem a little deeper, clearer and tighter than the jj’s it came with. It’s not a high fidelity stereo amp but they sound great for what I need!
Tubes sound great!
Installed a matched pair of these TAD EL84-STR's in my Vox Night Train 15H and got a loud hum after taking the amp off standby, after a warm up for 3-4 minutes. Gain and volume all the way down, the amp is self biasing. The hum would disappear after 2-3 minutes. But this is occurring less though, the more the tubes are being broken in and used. These tubes break up a lot earlier than the Preferred Series 7189 I had in before. I have to dial back the gain a lot on my amp. It's an aggressive tube, with a wide fat tone. It's great for rock or crunch. Lots of bass and good midrange, but less headroom compared to what I had in before.
Excellent...! These TAD EL84 STRs add a 6V6 flavor muscle to the already *very* good EL84 sound. I'll definitely be staying with these - the best new production EL84s I've heard (hear that Ruby/JJs...?). If only TAD improved new production 12AX7s like this...!
Excellent...! These TAD EL84 STRs add a 6V6 flavor muscle to the already *very* good EL84 sound. I'll definitely be staying with these - the best new production EL84s I've heard (hear that Ruby/JJs...?). If only TAD improved new production 12AX7s like this...!
I have been using these TAD EL84str power tubes for quite some time now and I have tried them all in my Soldano amp. These have the best of all worlds for lows, mids and highs. The bass response from my amp is absolutely fantastic. I play classic rock and blues guitar and these tubes really are the best I have ever found so far. Way better then Sovt, JJ, Mull, you name it I tried it. Been playing for 45 yrs, 63 and still rocking on the weekends. Love these tubes so much I don't have any others on hand anymore. Sold everything else I had. I might add I use Sylvania 12ax7's for the pre-amp tubes. Best I have found in 12ax7's. NOS Sylvania's with the green lettering.
Application: Heathkit UA-2 amplifiers. These are competent tubes with no bad qualities that I could hear. Perhaps nearly the equal of the Sovtek tubes I generally use. As such, they're not worth the extra cost.
The TAD EL 84 STRs have about 35 hours of play time on them and continue to improve. Best characteristic of the tube is the impression that my amp has additional power. These tubes are great!
Replace power tubes in Vox AC15C1X. Nice sounding tubes!
Quick delivery. And it sure was nice getting a phone call to clarify what I was going to receive. The Tubes I was replacing were about twenty years old (EL84 TAD-str's)so bottle length was longer than the old tubes. A little tweaking of the hangers solved that problem. They're a little crisp sounding. I'm running them in class A so it shouldn't be long before the mellow out a bit. All and all I'd say a good re-tube for my '94 Laney VC30 112. Thank you.