Since 1993 Copyright Notice
Electron Engine ™
Printed Circuit Boards by Emissionlabs.
EE51 Moving Coil Board
Introduction
This high quality board is available as ready build version, but without the transformers on it. The possible transformers to use are, LL1636, LL1678, LL9226 or LL9226XL. These can be ordered with the board separate. If wanted, we mount them for you at the board. EE51 features two step up factors per transformer, a ground lift option, and adjustable needle damping. Depending on the transformer, gain can be set: 10x, 20x, 16x or 32x.
EE51 Order Number: 310-051-09. What is pictured here, is what you receive. The PCB has the parts mounted on it, as you see here. Transformers must be ordered separate. If wanted, we solder the transformers on the board for you. Then, the board is ready to use.
Features:
- RCA connectors, Jumpers, Ground connector and PCB is gold plated.
- The jumpers are a special high contact force type.
- The resistors are low noise, metal film.
- We do not supply a housing with it. You can use your own housing, or use Hammond Box 1590B3 in which the PCB fits nice.
Dimensions:
- Bare PCB without connectors: 94 x 60mm
- Height with transformers mounted: 25mm.
- Drill holes for RCA Connectors: 13mm
- Fits in Hammond Box 1590B3 (not supplied by us)
Gain settings
LINE | P/N |
Low |
High |
High Gain: Set jumpers H1, H2, remove Jumper L. Low Gain: Set Jumper L only, remove Jumpers H1 and H2. | Ground Lift |
Frequency |
01
| LL9226 |
1:10 | 1:20 | General purpose, Cobalt core, amorphous transformer. | recommended Closed | 5 Hz -- 100 kHz +/- 1.5 dB |
02 |
LL9226 |
1:10 | 1:20 | Larger version of LL9226(or XL), with slightly less loss, and even higher frequency range. | recommended Closed | 4 Hz -- 90 kHz +/- 1.5 dB. |
03 |
LL1636 |
1:10 | 1:20 | Cobalt core, amorphous transformer with internal shield. Lundahl's only MC transformer with internal Faraday shield. Best product for environment with a lot of mains hum. | Closed or open. If open, shield is activated. | 10 Hz -- 90 kHz +/- 1.5 dB |
04 |
LL1678 |
1:16 | 1:32 | High Gain, Cobalt core, amorphous transformer. | recommended Closed | 10 Hz -- 35 kHz +/- 1 dB |
| Explanation page: To choose between MOVING COIL transformers LL1636, LL9226(or XL), LL9226(or XL)-XL and LL1678 |
Ground Lift Option (GND jumpers)
Ground lift is only used for failure finding, or for using the specially shielded LL1636 transformer, which can handle extreme hum situations. For normal use, Ground Lift it is not needed. This means, the GND Links are normally permanently inserted, giving primary and secondary a common ground.
Needle damping Setting
Correct needle damping is important for good sound. The cartridge is mass-spring system like any other. Though very tiny, the moving system does have a certain mass. This mass consists of the needle plus cantilever, but most of it is the moving coil itself. This is suspended in rubber, and there we have our spring. Any mass-spring system will resonate, while it gets shaked. Low frequencies of recordings will nicely do that, but external rumble can do the same. If that happens, you must not think of a "tone" which is generated, but rather the needle makes unintended movements, which in severe cases even cause the needle to jump out of the groove. When this happens, it may seem more needle pressure solves it. But it may as well be lack of damping. Much before the needle actually jumps out of the groove, the sound was already not very good any more. Unintended movements means simply, the needles doesn't follow the groove as it should.
How is the needle damped?
The first part of the damping is achieved by the manufacturer, already inside the cartridge. The rubber part allows movement, but gives also some friction to the movement. This is a form of damping. However older systems change the composition of the rubber, and over the years it may get harder, or softer. This is not a defect, and it can be electrically compensated, with EE51.
The second part is done by the phono amplifier, which acts as an electrical load to the cartridge signal, and this gives the minimum required damping.
The third and final part is by the damping resistor we add on the EE51. The manufacturer specifies for this, the so called minimum load resistance. Any value from no load at all, to this minimum resistor value is possible. Which value exactly is the best, depends on all factors you have. Like head shell weight, just to mention something. For this, EE51 has some resistors, which can be connected in 5 steps as in the table.
Best damping is found this way
As an example, let's look at the DENON DL103 cartridge, below here in the cartridge table. For best output signal, it needs 1:20 gain. Also you can see, DENON specifies a minimum load of 100 Ohms. In the jumpers table, when looking in the 1:20 column, we see there, the VERY SOFT setting gives 118 Ohms. Probably this is a good setting for the DL103. It depends however also on the tone arm, and needle pressure you have chosen. So it is recommended to try also the setting SOFT, resulting in 98 Ohms. The setting MEDIUM would probably mean too much damping, but as said before this is very individual, and you need to try it. Whereas HARD and VERY HARD for the DENON DL103 makes no sense. But, as we repeat here, you can only try this out. Nobody can advise it on paper.
Too much damping gives loss of high frequency, and loss of stereo information. That is because faster needle movements (as needed for high frequency) get damped a lot more. The stereo information is coded in the vertical needle movement, which get damped just as well.
Not enough damping leads to reduced groove contact during loud sound parts, which is a form of distortion, and loss of stereo information as well. In severe cases it can even cause the needle to skip some grooves with very loud music parts. This is mistakenly judged sometimes as a bad adjustment of the tone arm.
You just need to find the best setting by hearing tests.
Damping |
|||||||||
A |
B |
C |
D |
GND |
Cartridge Load at 1:10 |
Cartridge Load at 1:16 |
Cartridge Load at 1:20 |
Cartridge Load at 1:32 |
|
Very soft |
X
|
470Ohms |
184Ohms |
118Ohms |
46Ohms |
||||
Soft |
X
|
X
|
390Ohms |
152Ohms |
98Ohms |
38Ohms |
|||
Medium |
X
|
X
|
X
|
320Ohms |
125Ohms |
80Ohms |
32Ohms |
||
Hard |
X
|
X
|
X
|
X
|
280Ohms |
109Ohms |
70Ohms |
27Ohms |
|
Very Hard |
X
|
X
|
X
|
X
|
190Ohms |
74Ohms |
83Ohms |
19Ohms |
|
Note: The Jumper A is used for the settings as you can see. But in fact, it switches the damping of the EE51 on or off. When off, this leaves only the damping of the RIAA amplifier, which is always a "Very Soft" damping. For instance, when set for "Hard", with jumpers A-B+D, just by removing Jumper A, you go from "Hard" to "Very soft". Like this you can quickly compare the effect, while playing music. This works for the other settings as well.
PART2. Building instructions:
These PCBs fit exactly into Hammond case, type 1590B3. This nice box, you can order it in five colors. Or, take any other box you like.
Never test an MC transformer with an Ohms meter. This will magnetize the core permanently, sound will be distorted. For this reason, buying second hand MC transformers, is generally not a good idea.
A project by Bratislav S. from Serbia, Belgrade.
Please note, we only sell the EE51 unit at the inside. Our customer send us these nice, inspiring pictures of his EE51 build.
Thank you Bratislav!
Drilling holes for the connectors
Above each connector is a dummy hole in the PCB. This can be used as template for the drilling holes. Here is a hint you may like: When drilling holes in Aluminum, use alcohol as a lubricant, and then drill at low speed. This gives a much nicer drill hole. You won't believe this if you have never tried it.
Grounding:
The PCB is double sided grounded, and the two mounting screws are also the ground connections. In general, screws of PCB's tend to get somewhat loose over the years. To prevent a bad ground connection by this, there is also a soldered ground connection. This should be connected with a wire, to the ground plug of the metal case. If the chassis is colored or surface treated (such as passivated aluminum), remember to clean the metal beneath the screw.
In addition to the four RCA Connectors, the metal case needs also a ground screw at the outside, which connects to the record player, with a simple single wire. Since Dec 2023, this ground screw is also provided, a nice gold plated version.
Settings for some cartridges
The EE51 board works with most cartridges needing a gain from 10x to 32x.
The table which is linked here, will quickly assist with the choice.
If a box is green, this is the recommended setting.
If a box is black, so no number is visible, the output signal is much too high or too low.
Special Situation, blue boxes. This may be useful for noisy pre amplifiers. A blue box generates an output signal above normal, thus improving signal to noise ratio. However it gives higher load to the cartridge, and needle damping becomes higher. This may be compensated by choosing the lowest possible damping. In case you want to go this way, ideally you can choose a green and a blue box. So in case the blue box generates too much damping, you can still go for the green box.
Here are some examples, considering the choices.
- Denon DL103. One of the most popular cartridges ever. LL1678 would be possible to use 1:16, it gives 3.9mV. Using 1:32 setting would give a theoretical 8.8mV, but it doesn't work well, otherwise this box would have been blue. The 8.8mV will not appear, because load on the cartridge is very high. Also it will give high frequency loss. So LL1678 makes only sense for DL103 when you already have a pair, and you want to try if it works perhaps. A better choice is the LL9226-XL transformer and set it for 1:20. This gives a nice 4.4mV, which is very good, and cartridge load is optimized, as with all green boxes.
- Fidelity Research FR-1 Mk3F. In the table, it has a blue box with LL1678 and 1:16. If your pre amplifier is too noisy, this by itself is the real problem. It may be solved however by choosing this blue box, and get 7.4mV signal. However there is some risk, because when it appears wrong, there is no green box setting. The official, recommended use for this cartridge is 1:10 with the transformer LL9226-XL This gives even 4.8mV which is even a very good value. So here, the recommended choice is LL9226-XL. Or, use LL1678 which has higher needle damping as intended for the cartridge.
- Benz Wood M2. It has only a blue box, and it is the only option anyway for this curious cartridge. Using a blue box means the damping may be higher as expected. From our side, we can only say it is a little bit risky to have only a blue box. Ask at Benz company if they advise this.
- Benz Micro Reference S Copper. This is a nice one for noisy pre amplifiers. In that case use the LL1678, and try it for 1:32. Though 32x gain is quite a load for the cartridge, it can take this because impedance is an incredible low 5Ohms. Even so, minimum load is low, with 40 Ohms. This is why the blue box is highlighted. In case some high frequency is lost, you can still go for the green box and get 4mV, which is a nice value. Some other brand cartridges give only 3.2mV and these are also good.
Fault finding hints
This MC unit designed to work right away. If there is hum however, the EE51 board has a some modes for fault finding