2A3-EH-G-PL
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2A3-EH-G-PL Gold Grid
What means the letter G <== Click there. Must read!
What means the letters PL
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5U4GB |
5U4GB
This is a new production 5U4GB, made by EHX as an exact copy of the 1970's American tubes.
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300B-EH-G-PL
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300B-EH-G-PL Gold Grid
What means the letter G <== Click there. Must read!
What means the letters PL
Ultra-long life, top-quality construction, and superior sonics make it the finest 300B available today. Like the original Western Electric 300B, it has the 8 course directly heated filament, 40 watt plate dissipation, classic large shoulder tube glass, and are available singly or in precision matched pairs. The 300B EH-PL plate curves and static DC characteristics (plate resistance, Transconductance, mu) also exactly match the originals so you can drop them into any vintage or modern 300B amp and realize the finest performance of any 300B made today.
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300B-EH-G-PL
Data sheet |
KT88-EH-PL
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KT88-EH-PL
What means the letters PL
Enlarge Picture
This KT88 are the ultimate quality KT88 available today from new production. Failure rate is virtually zero, and the matching is done with the double burn in "PL"method. Sextets and Octets cost no extra, but we must have them available.
For manufacturers we also can supply a 100pcs bulk pack at OEM Prices.
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KT88-EH-PL
Data sheet |
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KT90-EH-PL
What means the letters PL
The KT90 can replace the KT88, but it is a different construction tube. The KT90 is made from elements of the big PL519 horizontal sweep tube for color TV's. The PL519 is in fact a tube with very high cathode emission, and it is a really good idea to make a HiFi tube from this. Grids and the plate were modified to make it compatible with the KT88.
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KT90
Data sheet |
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6C45PI-EH-G
What means the letter G <== Click there. Must read!
A most amazing tube from the days of the cold war. This is a frame grid tube, meaning the grid wires are so extreme thin, you can not see them with the eye. If you remove the gird from a broken tube, it looks like a light absorbing, transparent foil. (same effect as sunglasses). This is how thin the grid wires are. You can't see them, but still they absorb some light of course. For making a grid like this, first a frame is made of hard metal. Around this frame, the grid is wound, and then frame and grid together go inside the tube. Like this, very precise tubes of high gain can be constructed. I really want to put upfront this most amazing technology.
Characteristic for frame grid tubes is the nice uniformity of transconductance. The 6C45 has a gain of 50x and it has enough plate dissipation to build a small SE output stage with it. Originally this tube was not made for SE stages, but it's a secret tip and it works very nice.
Quality
Not so nice news here, but a good solution still. This is new production, of an extremely hard to make tube. This results in low factory yield, it can not be avoided. You can not blame the factory for this by itself. What does make me unhappy, they seem they ship any tube whatsoever. Also the ones that I think are questionable. (Same as Chinese factories normally do). For this reason, we recommend to buy only the selected versions that we sell, tested with the AMPLITREX computer tester. Another problem these tubes can have, is vacuum defects, but this is a general problem with all Electro Harmonix 9 pin tubes. Specially for 6C45 which gets extremely hot, the smallest sign of something not 100% with the vacuum, is a reason to reject the tube. The practical situation proves we are right by this. If you store such tubes which are initially "ok" but perhaps the vacuum not exactly perfect, then after some years you find them on the shelf with a white getter, and all vacuum lost. So the ones we sell, are selected for perfect vacuum, and high transconductance. Actually this process we have, seems to reject the weak ones very good.
So we do not want you to be afraid of this tube, but you should be afraid of 6C45 that you buy from any random sellers in the internet, which only want to sell via the price, and not via the quality. That doesn't pay off with 6C45.
Select the right transformer:
This tube is ideal for use with Lundahl LL1660 driver transformers. You can wire the transformer for instance in a 4.5 : 1 step down scheme. This will still leave you with a total gain of 50/4.5= 11x which is a good number. The good part is now, the output impedance of this tube is reduced with a factor (4.5)² = 20. So the original Ri of the tube, of apr. 1100 Ohms will appear as 55 Ohms (!) at the output of the LL1660. This 55 Ohms is very nice for head phone amplifiers, or pre-amp outputs. So a line output stage with this tube, using the LL1660/25 would have these specifications:
Design example for line output stage:
Transformer LL1660/25 with connection scheme: Alt Q (see this website for Lundahl transformers)
- Stage Gain = 11x
- Output impedance 55 Ohms
- Frequency range 10Hz...35kHz at 1db
Note, when designing with LL1660: First let's say here the normal LL1660/25 works very nice. For superior noise isolation with line driver amps, or for user increased safety with head-phone applications, the "S" version (shielded) can be used. The shield is in between primary and secondary and must be grounded. Both the standard or the "S" version are available with amorphous core.
Data sheet of LL1660
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6H30Pi-EH-G
This tube is also from the best times of Russian military tube making. Actually is was forbidden to export it from Russia, I believe until 1995. It has a very large getter for longest lifetime, and you can best see of this tube as a higher voltage, higher power version of the ECC88. The pin out is the same, also the data are comparable, but is it not fully equivalent. WIth some minor changes ( sometimes without changes) you can adapt most ECC88 circuits for the 6H30.
6H30 is widely used today as driver tube in very high ended audio equipment. Pictured is the Sovtek tube here, the EHX looks the same but has gold pins, and gold metal printing which can never wipe off or burn. The balanced version has the two systems inside one bulb matched to each other.
What means the letter G <== Click there. Must read!
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6H30Pi-EH-G
Data sheet |
6L6-EH-PL
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6L6-EH-PL
What means the letters PL
Enlarge picture. Modeled after the vintage RCA 6L6GC "black plate," the 6H6-EH features large plate dimensions and improved grid structure for increased power handling capabilities. Extra for road amplifiers. Features mica spacers with metal springs to eliminate tube rattle and microphonics. The 6L6-EH offers tone and performance superior to any other 6L6 or KT66 type.
For manufacturers we also can supply a 100pcs bulk pack at OEM Prices.
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6L6-EH-PL
Data sheet |
6SN7-EH |
s6SN7-EH
High quality 6SN7's have virtually disappeared until now. The 6SN7-EH-G is a beautiful sounding tube, low noise version, on par with the famous RCA's red base 5692. The 5692 is a very special tube of unique production standard. Check here for more on the 5692. The We say here the 6SN7-EH is no direct copy of the 5692, and it doesn't have the special selection that a 5692 has by default. But.. it features the extra support bars, the higher weight, and has the looks and feeling of the famous 5692. Check the price list, and you will see this tube is attractively priced, probably the best buy you can make for a top quality 6SN7.
For manufacturers we also can supply a 50pcs Qty at OEM Prices, individually packed.
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6SN7-EH-G |
6SN7-EH-G
What means the letter G <== Click there. Must read!
This tube maintains a linear response while being able to accept a full voltage. Vintage amp users and audiophiles will be thrilled to find that a superior quality, ultra low noise replacement finally exists. GOLDPIN version!
For manufacturers we also can supply a 50pcs Qty at OEM Prices, individually packed.
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6SN7-EH-GB |
6SN7-EH-GB Balance Single tube
What means the letter G <== Click there. Must read!
This is the GB - Gold-Balanced version. This tube is simply the FINEST 6SN7 available today from new production. It maintains a linear response while being able to accept a full voltage. Vintage amp users and audiophiles will be thrilled to find that a superior quality, ultra low noise replacement finally exists. GOLDPIN version!
Semi Long Plate version, with superior dissipation over the originals.
Very thick GOLD plated pins.
GB = Gold-pin, Balanced tube.
 Must read this!
Balanced means, both triodes within one tube are identical. Only like this both tube halves will produce the same sound. We do this matching both for plate current, and Transconductance, using official RCA operating points. As a reference we take the balancing information from the 5692. There is no better reference. ( See above). The system balancing was an official part of the original RCA 5692 Data sheet, and it was specified as 2mA maximum difference between two triodes within one tube. We use for the 6SN7-EH-GB a difference of maximum 1.5mA, which is even better than the 5692!. All measured tube data is on the tube box. So before a tube can be called balanced, first both halves must first have the same plate current, and after that have the same Transconductance, within a limit of 0.25mA/V (=250mMhos). It must pass both tests in sequence.
Balancing a "GB" single tube means: only like this, both halves are guaranteed to have the same plate Transconductance, the same bias and same gain and by this produce the same sound. This is done on a calibrated tube tester, which measures the tube data with a 1600 Hz test tone. (So not one of those Hickok testers, and nobody knows what the tester is really testing)
12AU7-EH-GB Balanced Matched Pair
(Compares to tube of type "5692")
Balancing a "GB" pair means: A single tube contains two triodes inside. A balanced pair means you receive two tubes containing actually four identical triodes.
Balanced tubes offer uniformity and stability in characteristics, and by this low operating costs.
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6V6-EH-PL |
6V6-EH-PL
What means the letters PL
With cylinder glass shape.
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6V6-EH-PL
Data sheet |
12AT7-EH |
12AT7-EH (ECC81)
Semi Long Plate version, with superior dissipation over the originals. Perfect for reverb circuits and drivers.
This tube has RHODIUM pins, for better contacts quality.
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12AT7-EH
Data sheet |
12AT7-EH-G |
12AT7-EH-G (ECC81 or E81CC)
What means the letter G <== Click there. Must read!
Semi Long Plate version, with superior dissipation over the originals. Perfect for reverb circuits and drivers.
Very thick GOLD plated pins.
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12AT7-EH-G
Data sheet |
12AT7-EH-GB |
12AT7-EH-GB. Balance Single tube.
(Equivalent to: ECC801S)
Semi Long Plate version, with superior dissipation over the originals. Perfect for reverb circuits and drivers.
Very thick GOLD plated pins.
GB = Gold-pin, Balanced tube.
Balanced means, both triodes within one tube are identical. Only like this both tube halves will produce the same sound. We do this matching both for plate current, and Transconductance, using official Telefunken operating points. The system balancing was an official part of the original Telefunken ECC801S Data sheet Balancing delta = officially: Max 3,2mA. ( See ECC801S Data sheet ) We balance better than original: We use Max 1.5mA. All measured tubes data is on the tube box. So before a tube can be called balanced, first both halves must first have the same plate current, and after that have the same Transconductance It must pass both tests in sequence. The Electro Harmonix tube appears very constant in production, so we could tighten the original specs down from delta=3.2mA to 1.5mA, and enough tubes will pass the test.
Balancing a "GB" single tube means: only like this, both halves are guaranteed to have the same plate Transconductance, the same bias and same gain and by this produce the same sound. This is done on a calibrated tube tester, which measures the tube data with a 1600 Hz test tone. (So not one of those Hickok testers, and nobody knows what the tester is really testing)
12AT7-EH-GB Balanced Matched Pair
(Equivalent to: ECC801S)
Balancing a "GB" pair means: A single tube contains two triodes inside. A balanced pair means you receive two tubes containing actually four identical triodes.
Balanced tubes offer uniformity and stability in characteristics, and by this low operating costs.
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12AT7-EH-GB
Data sheet |
12AU7-EH |
12AU7-EH (ECC82)
Semi Long Plate version, with superior dissipation over the originals.
This tube has RHODIUM pins, for better contacts quality.
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12AU7-EH
Data sheet |
12AU-EH-G |
12AU-EH-G (ECC82 or E82CC)
What means the letter G <== Click there. Must read!
Semi Long Plate version, with superior dissipation over the originals. Perfect for reverb circuits and drivers.
Very thick GOLD plated pins.
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12AU7-EH-G
Data sheet |
12AU7-EH-GB
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12AU7-EH-GB. Balance Single tube.
(Equivalent to: ECC802S)
Semi Long Plate version, with superior dissipation over the originals. Perfect for reverb circuits and drivers.
Very thick GOLD plated pins.
GB = Gold-pin, Balanced tube.
Balanced means, both triodes within one tube are identical. Only like this both tube halves will produce the same sound. We do this matching both for plate current, and Transconductance, using official Telefunken operating points. The system balancing was an official part of the original Telefunken ECC8021S Data sheet Balancing delta = officially: Max 2mA. ( See ECC802S Data sheet ) We balance better than original: We use Max 1.5mA. All measured tubes data is on the tube box. So before a tube can be called balanced, first both halves must first have the same plate current, and after that have the same Transconductance It must pass both tests in sequence. The Electro Harmonix tube appears very constant in production, so we could tighten the original specs down from delta=3.2mA to 1.5mA, and enough tubes will pass the test.
Balancing a "GB" single tube means: only like this, both halves are guaranteed to have the same plate Transconductance, the same bias and same gain and by this produce the same sound. This is done on a calibrated tube tester, which measures the tube data with a 1600 Hz test tone. (So not one of those Hickok testers, and nobody knows what the tester is really testing)
12AU7-EH-GB Balanced Matched Pair
(Equivalent to: ECC802S)
Balancing a "GB" pair means: A single tube contains two triodes inside. A balanced pair means you receive two tubes containing actually four identical triodes.
Balanced tubes offer uniformity and stability in characteristics, and by this low operating costs.
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12AU7-EH-GB
Data sheet |
12AX7-EH
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12AX7-EH (ECC83)
Semi Long Plate version, with superior dissipation over the originals. A fine standard tube.
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12AX7
Data sheet |
enlarge
12AX-EH-GT
For guitar
Selected
Version |
12AX-EH-GT (ECC83 or E83CC)
What means the letter GT <== Click there
Semi Long Plate version, with superior dissipation over the originals.
Perfect for reverb circuits, and guitar amplifier circuits with high gain. This tube is specially selected for a darker, "brown sound". So all applications where your amplifier suffers from a harsh kind of distortion, you should try this tube. Also such tubes with too large differences between the two systems inside one glass bulb are screened out
Very thick GOLD plated pins.
What Electro Harmonics considers a good way to test tubes
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12AX7
Data sheet |
enlarge
12AX-EH-GA
for HiFi
Selected
Version |
12AX-EH-GA (ECC83 or E83CC)
What means the letter GA <== Click there
Semi Long Plate version, with superior dissipation over the originals.
This tube is selected for use in HiFi amplifiers. (For guitar amplifiers take the GT Version) Such tube with lower bias setting than normal are screened out, and also such tubes with too large differences between the two systems inside the bulb are screened out
Very thick GOLD plated pins.
What Electro Harmonics considers a good way to test tubes
What we think is the BEST way to test tubes
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12AX7
Data sheet |
enlarge
12AX-EH-GB
for HiFi
BALANCED
TUBE |
12AX7-EH-GB. Balanced Single tube.
What means the letter GB <== Click there
(Equivalent to: ECC803S, ECC83 or ECC83CC)
Semi Long Plate version, with superior dissipation over the originals. Perfect for reverb circuits and drivers.
Very thick GOLD plated pins.
GB = Gold-pin, Balanced tube.
Balanced means, both triodes within one tube are close, or identical. This is not always important, but it is important in: Symmetrical circuits, phase splitter circuits for PP amps, and stereo amplifiers where one tube is split over two channels. Only like this both tube halves will produce the same sound.
We do this matching both for plate current, and Transconductance, using official Telefunken operating points. The system balancing was an official part of the original Telefunken ECC803S Data sheet (Balancing delta by official TFK Data sheet = Max 0,15mA). This is extremely tight for this tube, though it can be done.
* Balancing a "GB" single tube means: only like this, both halves are guaranteed to have the same plate Transconductance, the same bias and same gain and by this produce the same sound. This matching is done on a computerized test system.
12AX7-EH-GB Balanced Matched Pair
(Equivalent to: ECC803S, ECC83 or ECC83CC)
*Balancing a "GB" pair means: A single tube contains two triodes inside. A balanced pair means you receive two tubes containing actually four identical triodes.
Balanced tubes offer uniformity and stability in characteristics, and by this low operating costs.
What Electro Harmonics considers a good way to test tubes
What we think is the BEST way to test tubes
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12AX7
Data sheet |
12AY7-EH
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12AY7-EH
This is a low microphonics, medium gain (40x) twin triode, with 9 pin socket. It is used for first stages in high gain audio amplifiers, where reduction of hum, microphonics and leakage noise are a first consideration.
This tube has RHODIUM pins, for better contacts quality. This is a shiny white metal. |
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12BH7-EH |
12BH7-EH
This tube has RHODIUM pins, for better contacts quality. This is a shiny white metal.
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12BH7-EH-G |
12BH7-EH-G
What means the letter G <== Click there. Must read!
Very thick GOLD plated pins.
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5751-EH-G |
5751-EH-G
What means the letter G <== Click there. Must read!
5751-EH-G is a low noise, long life version of the ECC83, with gold plated pins. The tube specifications has very small differences compared to ECC83, but this tube is used to replace an ECC83 in all circuits, where you want best reduction of noise an hum.
Very thick GOLD plated pins.
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6922-EH |
6922-EH
The 6922 is a long life version (10.000 hours minimum), of the ECC88 (6DJ7).
This tube has RHODIUM pins, for better contacts quality.
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6922-EH-G |
6922-EH-G
What means the letter G <== Click there. Must read!
Very thick GOLD plated pins.
Real frame grid tube, by EHX it's own technology
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6922-EH-GB |
6922-EH-GB
GB = Gold-pin, Balanced tube.
What means the letter G <== Click there. Must read!
The 6922 is a long life version (10.000 hours minimum), of the ECC88 (6DJ7).
When additional this tube gets gold plated pins, it was called E88CC.
The G-Version has very thick GOLD plated pins.
Balanced means, both triodes within one tube are identical within a pre-defined limit. Only like this both tube halves will produce the same sound. We do this matching both for plate current, and Transconductance, using official Telefunken operating points. The system balancing was an official part of the Telefunken tubes like ECC802S etc. However, for 6922 this officially was never done by manufacturers. Still we offer it for this tube, because specially with this tube it is more important than with any other audio tube! This is the number one tube where people report sound differences quickly. We use: Balancing delta = Max 1,5mA for the plate current (Static parameter) and 10% maximum difference for the transconductance (dynamic parameter).
So before a tube can be called balanced, first both halves must first have the same plate current, and after that have the same Transconductance It must pass both tests in sequence. This tube is a high gain (50x) AND a low voltage (100V) tube type at the same time. These two requirements are very hard to meet AT THE SAME TIME. So this makes it very difficult for the manufacturer to produce those tubes. The question is what will they do with the tubes that are not so good. Good NOS E88CC is almost impossible to buy now. It is normal that within one glass, you can have two quite different tubes, also with NOS. So very few tubes pass the balancing test.
Special ECC88/6922 note for technicians: I think we can say, this is one of the most difficult tubes, if you need a good replacement. If any discussion comes up about about too much noise, or bad sound, it is with this tube. Where does this come from? There are many amplifiers using this tube in so called SRPP circuits. As you know, with a circuit like this, both halves of one tube are put in series, so must draw the same plate current per definition. Problems will come with an unselected tube, where both tube halves by itself actually would have liked to draw a different current. The result of such an unbalanced tube in an SRPP circuit is, both tube halves are in a "battle" about what current they can draw. One of the two halves will try to dominate, and determine the final current for the circuit. The voltages in the circuit are now not correct any more. Also the actual current drawn can be too high or too low, depending if the "higher" or "lower" current tube is the winner. If a stronger unbalance occurs, the circuit will produce more noise than normal and add too much distortion. Also tube wear out can be the result of this, and an acceptable result in the beginning will soon be less good, and the complaints starts from the beginning. To prevent any problems like this, for an SRPP circuit ONLY balanced tubes should be used.
Balancing a "GB" single tube means: only like this, both halves are guaranteed to have the same plate Transconductance, the same bias and same gain and by this produce the same sound. This is done on a calibrated tube tester, which measures the tube data with a 1600 Hz test tone. (So not one of those Hickok testers, and nobody knows what the tester is really testing)
6922-EH-GB Balanced Matched Pair
Balancing a "GB" pair means: A single tube contains two triodes inside. A balanced pair means you receive two tubes containing actually four identical triodes.
Balanced tubes offer uniformity and stability in characteristics, and by this low operating costs.
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6550-EH-PL
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6550-EH-PL
What means the letters PL
The 6550EH is the finest current production tube for any amp using 6550 or KT88. The 6550EH offers the maximum power of any 6550 with the linearity guitar and bass players want. With 42 watts of plate dissipation in tetrode operation and 44 watts in triode, the 6550EH offers an improvement in power over even the most desirable vintage types including the Tung-Sol 6550 and Genelex KT88. This extra headroom in a 6550EH equipped amp means bass players can finally realize the full dynamic range of the instrument and the sweetest tone available.
The extra ruggedness of the 6550EH was engineered with the punishing abuse of guitar amps in mind. The nickel steel side rod mica supports ensure that the 6550EH will hold up in even the most punishing environment of high powered bass amps like the Ampeg SVT and combos where the tube is only inches from the speaker and still deliver the sweetest tone of any 6550 or KT88. The 6550EH will greatly improve the performance of any amp using 6550’s but can also replace the KT88 in any application.
For manufacturers we also can supply a 100pcs bulk pack at OEM Prices.
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Data sheet |
EL34-EH-PL
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EL34-EH-PL
What means the letters PL
Vacuum Tube Valley journal says, "... the new Electro-Harmonix tube comes very close to the sonics of a Mullard EL34, and is balanced throughout the entire music spectrum. Bass goes deep and is tight, mids are sweet and well defined and highs are detailed and extended." Sextets and Octets cost no extra, but we must have them available.
For manufacturers we also can supply a 100pcs bulk pack at OEM Prices.
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Data sheet |
EL84-EH-PL
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EL84-EH-PL
What means the letters PL
The new EL84-EH faithfully recreates the classic Mullard design. Triple laminated plate material and selected screen wire increase thermal dissipation. The EL84-EH is a remarkable reproduction of a vintage tube that is capable of maintaining its sweet and musical tone under any voltage conditions.
For manufacturers we also can supply a 100pcs bulk pack at OEM Prices.
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