Belarus 57

[puudub]

Hi, I'm new here and to tube amp building, but not to electronics in general. Been looking around the forums and youtube (thanks Doug and Blueglow for very good videos) for about a year with intention to build my own tube amp.

Anyway long story short. I just acquired an old russian Belarus 57 tube radio passed on from my great granddad. In current form the radio isn't much use as radio frequencies have changed etc. and the radio is waiting to be given a new life.

Picture down in attachments

Schematic down in attachments (from www.radiomuseum.org)

As I assume many of you aren't familiar with russian letters, here is a list of tubes (western counterparts between brackets):
V1 - 6N3P
V2 - 6K4P
V3 - 6A2P
V4 - 6K4P
V5 - 6Zh3P

V6 - 6N2P (5751/12AX7)
V7 - 6N2P (5751/12AX7)
V8 - 6P1P (6v6/EL90)
V9 - 6P1P (6v6/EL90)
V10 - 6E5C

Left side of the schematic seems to be devoted to the radio part and right side to the amplification part. So basically 2x 12ax7 and 2x 6v6.

So far the idea with this amp is to gut it for parts (tubes, chassis, transformers, cabinet) and to rebuild it using some other schematic. First thing that popped to my mind by looking at the tubes was 5E3. Love the cleans and edge of the breakup, but not so much the overdrive, as I'd like the amp to be versatile enough to be able to play higher gain stuff like metallica, AC/DC.

Mojotone has added more gainy channel with their blackout amp. Also robrobinette's lead channel mod: https://robrobinette.com/5e3_Modifications.htm#Lead_Channel

Any input on this topic would be much much appreciated. Any schematics, ideas, opinions or am I even at the right path to my goal?

All the best,
Marko

[tubenit]

That's a very cool looking radio!  Thanks for sharing the picture.

Gutting and rebuilding it into what you want is a reasonable idea.  The 5E3 Deluxe would fit your tube line up well. I think you are thinking your way thru this quite well.  You have two 12A_7 tubes and two 6V6 tubes.  Since you had quite a few tubes, you could consider adding a 3rd 12A_7 for something like a one tube reverb  (info in ARCHIVES). 

https://el34world.com/charts/Schematics/files/Fender/Fender_deluxe_5e3.pdf

With respect, Tubenit

[tubenit]

This could be a candidate for the amp also.  And has some similarities with a 5E3 but with a paralleled V1 (for 30% more gain without increased floor noise),  James Tone Stack  (see Duncan Tone Stack Calculator), a PPIMV  (post phase inverter master volume) and a "one tube reverb".  The Carolina Blues Special is one of my favorite amp designs. I built 4 of these and liked how they turned out.  Two of them were built out of Bogen PA systems.   I may have a paralleled turret layout with the schematic also  IF this is something you're interested in.

* Note Sluckey's comment that you'd need solid state rectification.

With respect, Tubenit

[sluckey]

Very nice looking radio! That's the most speakers I've ever seen in a table top radio! I would try very hard to keep the looks of that, including the dial plate and push buttons. And you have a tuning eye (magic eye) that would look neat with audio connected to it.

Using a rectifier tube is not a good option because the PT has no center tap. You could use a Hybrid bridge by using an EZ81 and two diodes but using a 5Y3 is not possible. I would just use a 4 diode FWB.

Several years ago I built an Ampeg 12B Jet in an old radio. Might give you some ideas for your project...

     http://sluckeyamps.com/RCA/RCA.htm

Please post your progress on this interesting project. Lot's of love here for this kind of stuff.

[PRR]

Is it functional? This much of it IS a fine audio system. Feed the top of the Volume pot. Change the FM RF into audio preamp(s). Put tone-stack between. Connect the Eye to audio.

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Pic1

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Pic2

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Pic3

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Pic4

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Got stuck on a small island due to large storm, haven't done anything with the radio due to this.

Anyway since back safe, decided to take some pictures, since I thought you guys might be interested in old soviet tech from 50's. I labeled all the pictures. Maybe bit of extra comments can make things more clear.

First you can see what all the buttons do, antenna position, short, mid, long, ultra-long (FM, 67-73mHz). Treble, bass, volume.

On the backside in the middle, are connections to input external music, and 2 different antennas.

Smaller speakers say OTK4 on them. Not sure but I think it means quality control no4. If they f'd up speakers multiple times they probably ended up in Siberia.

Front panel has all the radio stations for all the frequencies listed by mayor cities. Minsk, Moscow, Tallinn (my home town) etc

Backside has speaker out

Voltage can be set by turning the knob. 127, 110, 220. Voltages used to be a mess during that time. Later on it was settled on 220V, but it took decades do switch all the regions.

_________________________________________________


Anyway as far as the project is concerned I have decided not to alter anything externally on that radio. I'd just feel bad neglecting a piece of history. So I decided to take out the internals and keep the speakers and cabinet and turn it into a bluetooth speaker. Sounds silly, but now it has a purpose and will keep all the original looks of the radio.

And for the internals I'd build it's own new cabinet. Got access to wood working studio etc. Love this stuff.

As for the rectification part. I'd keep it original. Haven't yet taken any voltage measurements, but I suppose it's good. Don't really care that it isn't tube based. I do have a oscilloscope for more precise measurements, but it isn't grounded and powerful enough, so for my own safety not going to use this.

For the layout of the new amp I have couple of options. Robrob's 5E3 (see his website) seems interesting as it has lead channel for more modern/neutral tones. But tubenit's CBS seems also good as it is something more special, something different. But I'm not sure about the tone. Will it provide me with enough versatility from pink floyd to metallica? Any audio examples? As far the schematic is concerned it seems really interesting. 5E3 inspired, treble, bass, gain, master volume.

I'm very new to this kind of stuff and can't simply look at the schematic and decide if it will be tonally what I desire.

[tubenit]

tubenit's CBS seems also good as it is something more special, something different. But I'm not sure about the tone. Will it provide me with enough versatility from pink floyd to metallica? Any audio examples

No, it will not do Pink Floyd to anywhere close to Metallica.  It's more old school blues/rockabilly.  I'm thinking this is probably not a good match for what you're looking for.     

This is the only soundclip of the amp I have easily available to share. (1st recording I ever made)

https://soundclick.com/share.cfm?id=6775767

With respect, Tubenit

*  OK,  I looked up a YouTube of Metallica's (since I am totally unfamiliar with their music) & I can safely say the Carolina
    Blues Special won't do Metallica.   

[puudub]

By metallica tone I meant it with pedals of course, but CBS clean sound was still too coloured for this.

As for the radio it was fully gutted and inspected. Transformers were super noisy, all tubes were originals with signs of been very worn, chassis is a structural part of the radio etc. It was cheaply made back then and is cheap now. So I feel bit bad for fully gutting it and not a single useful component.

Anyway I threw a laptop PSU and some bluetooth and transistor stuff into it that I had laying around. Sounds actually quite good and now lives on as a prop radio furniture.

I still liked the idea of old russian tubes, which are literally 1.50$ ea and stored 250km from me. So I ordered all the parts for Trashy Wreck build. A russian tube version of Trainwreck Express amp. Might post a pic here when done.

Thanks for all the help! Although in the end the project turned to 0...