Elektrofon VF-25

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An old Swede this time out then. A,i presume,-50´s era PA amp that has seen better days. Picked it up on our local e-bay.
VF-25 for outright power. At 10% distortion no less! WTF?



Uhu. The various jacks i guess we can attest to being outdated. That half worn "S" sticker to the left is the former Swedish state seal. Tells us that the amp conforms to,at the time,Swedish law.



Again an amp with a half odd tube setup. The twin 6L6G´s to hand us them 25 watts and in turn a 5U4 rectifier to make it all happen. 25 watts? Yeah well,it´s a cathode bias amp...



Embossed into the sheetmetal no less.



Then? 7F7? WTF? Well,as it turns out the 7F7 is a 6,3V tube,as far as heater,after all. A twin triode high mu tube. Might very well be useful.
From an amplification point of view a sort of take on the ECC-81/12AT7. Sort of...



Build in itself i guess we´ll have to dub as neat and to the point. Nothing much to bitch about IMO. Of course the thing needs a little TLC after 70yrs...hello!
Worse tho.
As it turns out the one side of the HT secondary is dead. Yep. Busted secondary HT winding. The one fresh side hands me 370VAC unloaded..
Thing is. This old piece sports one of them old "melt" fuses on the PT and that looks brand friggin new!
The tube rectifier,the 5U4,sure doesn´t look like it needs any help either and nor does it look to have been replaced recently. Hm. Weird. Really really weird.



Yep. That there is a "death cap" alright. That aside,as stated..neat and to the point.



...and see this has me a bit confused too! I KNOW that one should NEVER judge a transformer by size really as permability and what not...well,that doesn´t come down to size. However,this thing is friggin minescule!

That said. Checked ESR of the caps and the usual 9yrds... Hooked a regular rectifier bridge up between the one working tap and the centertap of the PT,ruling the tube rectifier out all together,and fired the thing up. Mainly to check that the rest of it works.
TBH is actually sounds alright. Not especially loud but...

This one might turn into a bit of work tho. If that PT turns out to be beyond salvage...well..

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Well. PT was shot alright..brings time for a fresh PT. That one there hands me 300-0-300...6,3 that´ll suffice to fire the entire thing up and in turn 5VAC for a tube rectifier. Courtesy TubeTown in Germany.



I´ll make this into an EL-34 amp. That and either a GZ-34/5AR4 or a 5V4 for rectifier.



Uhu. Rubber grommets are good as is an IEC jack.



So. Decision was made to replace the OT too. We´ll see where that takes me but that there is an OT from an old scrapped amp of mine. Indeed for EL-34´s but with secondary taps for 4 Ohms only. Hm.
In short there´s not all that much Elektrofon left but..comes with the territory i guess.



Giving thought to a "solid state vs tube rectifier" switch. Seing the HT AC voltages a 5U4 is out..so either GZ or 5V4 it is.



Yep. Fresh meat as far as capacitance and what´s more fuse holders out the whazzo. Uhu,there´s a bunch of them that resides within too.
Of course the tube rectifier socket´s seen the add on of "saver diodes" as well as individual fuses for each side of the HT voltage.

Seing that the next step i guess is a bias board. Nothing all that much difficult about that i guess and i guess i´ll set that up in such a manner that the amp will do EL-34´s and 6L6´s both.

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A faceplate. Faceplate is good,we can do with a faceplate. What´s more you can see that the entire octal setup for preamp has been replaced as well.
Which to part brings me to the hood,looks and all that. The cooling "screen" at the top of it has sure seen its fair share of a beating and thus...it´ll take either a fair amount of TLC to turn straight again with some bodyshop tools..or cut it out and replace all together. Please have in mind that i need to be able to hook the carrying handle to friggin SOMETHING down the line..



Right. Bias board. A setup you´ve seen me use numerous times by now. One that is compact,simple and to the point. Dual adjustments,one for each powertube.



The thing´ll need a block-off plate of sorts fabbed for out rear too. No argument. That said i looked around the parts bins of mine and dug up an old choke of 5H from an old Philips. Cool enough.



Yep. This one´ll sport that last circuit of mine too. In other words there´ll be two 6L6 such amps,one EL-84 such..there´s one 6V6 and now for this EL-34 one.

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Uhu. Up and running and about sounds on par i´d say. However it´s low on power...have done a bit of measuring around and suspect that to be the OT sorry to say.
Got an old Drake standing around i´ll try...and what´s more the stocker as well. As is it hands me like just the other side of 20 watts and that´s simply not up to par.



From a pure looks point of view i feel i need to get the Elektrofon insignia on there again. As you also can see..the top of that hood is REALLY dented...

Well lads. To be continued..

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Yep. With the fresh laser cut logo even.

Sounds da bomb,what can i say?