Update of the 15W-15W Hi-Fi Tube Amp

Lack of time is what always lags behind projects. Finally, the phono preamp is nearly finished. The configuration is different from the original one, in this one 4 double triodes are used instead of the original 3. The RIAA respond is based in pasive RC filtering. The final result is much better and fitted in the RIAA curved with a clean output. The SNR and final gain are not measured jet, but it sounds as a perfect preamp for MM&MC cartridges.

I have enjoyed a little bit of  Jazz, Blues and Rock with some interesting tonal features, although as soon as it is integrated with the KT88 power stage, it will require some calibration based in owner's taste to empower the experience.

The power supply is in prototyping  process. Hope to get it ready ASAP in order to deal with the power stage.

While working in the phono preamp, some ideas for a future guitar & bass amplifier, it is in the "must do" list.

Binson Echorec 2 - Power Supply

This is a typical power supply configuration for a tube device using silicon rectifier. Transformer with several windings, rectificaction, nice reservoir, Pi filter and RC stages. Two output windings, one is a 6,3V for the heaters and the other one is basically an insulating one for the HT. The binson is based in ECC83, does not need to get to messy with HT.

Transformer was OK, passed all testing with honours, wich is always a good relief. Took out the double caps and choke to inspect & check them.

Nice Sprague caps, after 50 years amanzingly still got acceptable capacitance, but awful ESR. The choke is not in its best days but gives good readings in all the tests. If finally the Echorec is restored I will take good care of the choke, for now it will be feasible for the initial device testing.

The caps were definitely out of the game in order to obtain an acceptable ripple, even though the choke would do a good job. It is difficult-impossible to find OMC replacements and in cases like this I always like to keep the original look as much as possible. So, the only way to go was to restuff the caps with new ones. Recapping can be a hard job, but really compensates the effort when it is well done. Check out the guts of this old boy:

Nice to see how it was manufactur with that rubber band holding everything and still in place. This is its new interior:

The other double cap followed the same process. I mounted them back, reinstall the choke and replace the carbon resistors. Afterwards, I was able to do some testing to the rejuvenated power supply, with and without load, getting pretty good results.

Next step is "updating" the cap-motor. I did some previous testing and it shows some minor problems.

Binson Echorec 2

No doubt  this is a great way to open this section, a Binson Echorec from the sixtis. An amazing tube echo delay well known by bands like Pink Floyd and Hawkwind.

A good friend and musician saved it from oblivion and decided to bring it back to life. Initially he just wanted to install 1/4'' jacks in substitution of the original inputs&output Geloso sockets. That first idea was pushed down into a list of "must do" after I was told for how long the Echorec was lost in a basement. Opening the Echorec to check its guts was the best way to confirm that it needs a deep restoration and calibration.

 

 There is some mods and repair wich were not done in the best way. A IEC socket was installed with an awfull chasis work, there is some rewired done with cheap amppliance power cord, hairy solder joints, wires bound together with tape, stripped screws, paint sprinkles....

This Echorec needs to "get in shape". But first the main functional blocks must be checked, restored and find out if they are viable: Power supply, motor and magnetic freewheel&heads. Only afterwards I will be able to take care of electronics.

Newbie in Hi-Fi family

Initial goals:

Around 15W+15W true tube, line and phono MM/MC inputs, SNR around -90dBV, penthode and ultralinear operation for everybody's taste, microcontrolled power supply, speaker protection, dynamic standby etc.

This is the first idea and starting point for the possible configuration of the Hi-Fi amplifier with phono preamp.

Next Project

We have a new project, a warm and tasteful Hi-Fi true tube amplifier for a 50m2 listening room. The device must include a phono preamp. After formal proposal and a few client design personalizations I have received the "Set sail!".

We will try to show the development of this special amplifier borned in the crossway of pure tube touch and today's tech.

The Born of an Idea:

A few days ago, Pepe contacted me requesting a proposal for a tube device with which he could enjoy his amazing vinyl collection to a new level. While grounding details, I was able to enjoy a little bite of his collection:  Genesis, ELP, Jethro Tull, King Crimson, Eric Clapton y John Mayall, Miles Davis y Coltrane and of course Neil Young. Among all we took a break with Pink Floyd album Pulse (1995 UK limited edition 25-track 4-LP vinyl box set), an analog recording willing to release all its power through a valve amplifier!

Future amplifier's full time work localization

Here we have the phono player waiting for its partner.

Pic of the commented Pink Floyd treasure!