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Sunday, May 13, 2012

Another E55L LCR phono preamplifier

Hi!

Here are some photos of a recently finished LCR phonostage with the E55L tube.




For those who don't want the six chassis of the modular preamp and who want to actually see the tubes, I have this more compact version which is in another style.



More compact as the six chassis version, but still a hefty preamp with external power supply:



The wooden frames are approximately 43 cm wide, 30cm deep and 12cm high. The frames are made of cherry wood.


The weight is quite hefty since it is loaded with iron. Two power transformers, seven (!) chokes, including a choke in the DC heater supply. Six signal transformers (excluding MC step up transformer). And the RIAA coils (In this case Tango EQ2L units.


This version was built on request. It is MM only, but MC transformers can be integrated. Gain is approximately 40dB. Depending on the selection of MC step up transformers, more than 70dB are achievable.



Sound is similar to my other LCR phono stages. The E55L is a good alternative to the EC8020 (which still remains my favorite). Very low noise and the E55L proofed to be very suitable in terms of microphonics. The mechanically damped mounting of the sockets helps of course.




Don't hesitate to contact me, if you are interested in such a preamp. It is also availabe as a kit. Kits can include all chassis material, but I can also provide partial kits if you want to build your own housings or if you have specific parts which you want to use in your preamp.

Best regards

Thomas

5 comments:

  1. Love the looks on these! No idea how they sound, but I like the design concepts.

    ReplyDelete
  2. Looks great!

    The E55L datasheet shows that the max grid resistance is 125kR. Is it possible to use a higher grid resistance, say 200kR?

    Thanks!

    ReplyDelete
  3. Hi Ken,

    The datasheet values are there for a reason. A higher resistance risks thermal runaway or other grid current related issues.
    Why would you need such a high grid resistance? The E55L has a rather high miller capacitance. If your source has trouble driving 100kOhm, it will also not be well suited to drive that miller cap.

    Best regards

    Thomas

    ReplyDelete
  4. Hi Thomas,

    Thanks for your reply.

    I'm thinking of building a SPUD with an input transformer of 5k:50k. 100kR pot is a bit on the low side and therefore I'm thinking of changing the pot to a 200kR pot. Seems like I need to get a 600:10k instead and really have a gutsy source in front.

    ReplyDelete
  5. Hi Ken,

    that sounds like a much better plan. I think the E55L would make a great tube for a spud amp. I ought to try that myself some time!

    Best regards

    Thomas

    ReplyDelete