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Klemt BS-40 / Soundclip

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Racing:
Please don´t get me wrong here,but why is it that many of you frown upon your domestic amps?
Let it be known,for the record,that working on tubers for a part time living i have the utmost respect for german engineering.
When it comes to "your" old tubers as well.

Anyways.
Klemt. Munchen. Back in the early -60s.
As a tube tech i´ve come to take an interest in Klemt made amps. Own several of them,Winston branded included. Showstars,BN-40´s,BS-40´s,Winston GA-200...PA-200...asf asf asf.

So. I ran into this BS-40 as a bare chassis over german e-bay. Picked it up cheap as "dead on arrival". Seller noted that it was "mit mod". Yeah yeah... ;D





What touched down with me was this rather beat up old BS-40 of,what i presume,1963 vintage. (Seing the grey coloured control knobs). Complete with dustbunnies and all. :bier:



Well. I cleaned her out with large amounts of alcohol and a brush...installed a pair of EL-34´s that were missing...looked her over and fired her up.
Sure enough. Sound.



As per usual coupling caps were leaking like crazy,so..replaced a few of those right off the bat.



"Mit mod". Riiiiiiiiiiiiiiiiiiiiight. ;D. Some Mr Handyman had replaced the stock 32uF+32uF can e-lyte with this mess...and basically had left that crap hanging within.
Enough of that already!



Don´t know how many of you are aware of it,but a Klemt BS-40 is basically just a Marshall JMP...just produced like 4yrs earlier than the JMP was an itch in Jimmys pants.
So.
I thought to myself,why not make this into a working mans JMP? One that is REAL cheap to keep and as rugged as the stocker.

Now. I was thinking along the lines..how to evolve on that and...realized that i needed to separate the two channels. Said n done..



I fabricated this real simple board that keeps a 9VAC trafo,a rectifier and a 4700uF e-lyte. That in turn runs.....



...these two buddies. Yep. A relay controlled "JMP" of sorts. Just..this time out a USABLE two channel such.



That in turn brought that i had no need for the extra two inputjacks,so these were scrapped.



Right. Working mans JMP. The stock ECC-808 are silly expensive and in my and my fellow techs ramblings up here in Sweden i´ve come across the russian 6n2p´s. In reality tubes that are real similar,just at 2 Euros a pop. Again...a WORKING mans JMP...



A differing jack was installed so that we can control the relays via a footswitch.



Lots of components were indeed replaced. Many were modified. As these 25V zener diodes installed for the powertube screens. Then a 100 Ohm resistor for each to combat EMI and RFI.



At this point i had myself a working specimen of a two channel JMP alright but....nah...just nah...





Well. Amp lacked a cab right,so i fabricated one out of regular pine.



As i pushed the envelope with the stock cathodefollower stage i soon realized that i was pushing to much amplitude inwards of that grid. I fooled around a LOT with it before deciding it was time for the bin....and ergo i remodeled that into a common anode driven stage instead.

Now. Mind you. LOTS of modifications has been pulled to this amp and the idea was,and is,a working mans JMP. Just with a greater span.
As such i deem it needed that the amp responds strongly to inbound signal. Ie; you need to be able to control it with the volume pot of the guitar should need be.

https://www.youtube.com/watch?v=PgwntussQ0w&feature=youtu.be

Well. There you have it. A Klemt BS-40 modified into something way more contemporary sounding.  :guitar:

What i´m trying to say here...you guys have TONS of these amps around. Be it Klemt,be it Dynacord be it Suprem...Hohner..whatever. They are dirt cheap as noone plays them anymore and...they ARE extremely well designed.
Use them.

RoehrenJeans:
Greetings to Sweden,
this amp sounds awesome - particularly if you are playing it !!!
Great job  :topjob:

I love your workin' men's JMP ... made for pure Swedish rock'n roll...
https://www.youtube.com/watch?v=tcDbGCv59bs&feature=related

Sorry about my ignorance, but until now, the first thing that came into my mind was "Michel aus Lönneberga" or "Pippi Langstrumpf" if I heard "Sweden" - now this has changed completely  :guitar: 

Greetings
Stoffel

P.S. your next project is an old HOHNER Orgaphon isn't it ?

Racing:
Hallo Stoffel.

Thanx a million  :topjob:

The Hohner MH-25 is already done. If you searh my YT channel there´s a video or two of it.

Right now there´s a couple of Dynacords in the pipeline at the shop of mine. An old Rex 212 combo and a Reference 502. Coming up is a REALLY old Geloso 219,which are real good platforms to  build on as well in my opinion.
I´m also currently putting the last bits together of a Schaller KV-50. A -66 vintage one which brings it´s one of the older ones resembling the AC-30 in looks.

For what it´s worth. Feel free to write in german if that´s easier to you. I comprehend it perfectly well,it´s just that it´s that much faster to me to write in english. Hope that´s ok and not to much of an inconvenience

Robinrockt:
Hallo,

klingt sehr amtlich :guitar:
Wäre ja irgendwie cool gewesen wenn die damals schon so einen Ton gehabt hätten >:D
Meiner Meinung nach hast du den Amp deutlich aufgewertet ;D :angel:
Der Wolf im Schafpelz :laugh: ;D

Grüße,
Robin

RoehrenJeans:
Hi again,
ich habe mir ein paar deiner Videos angesehen - eine tolle Sammlung hast du da beisammen.
In meinem Musikkeller stehen mittlerweile auch ein paar Exemplare deutscher Ingenieurskunst der 60er Jahre ;-)
Ein Dynacord DA16, ein JAZZ und ein alter SIEMENS 6SELA 2524 ...
Mein nächstes Projekt wird ein Favorit I, der schon auf der Werkbank liegt. Den möchte ich entkernen, d.h. das ganze Transistorvorstufen- und Tonestackzeug rauswerfen und neu aufbauen. Wenn ich das richtig gesehen habe, geht das in die selbe Richtung... 2x EL34 mit Gegenkopplung.

Die zusätzliche 9V DC hast du lediglich für die beiden Relais eingebaut ? Ich hatte mir überlegt ein 48V Miniatur-Relais an die Biaswicklung mit dran zu hängen ... separat gleichgerichtet und mit Freilaufdiode versehen... keine gute Idee ?

Solltest du von deinem Umbau eine Schaltplan dokumentiert haben, würde ich mich freuen, wenn ich da mal drauf schauen könnte - gerne via PN.

Viele Grüße
Stoffel

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