Well,this is an early/mid -50´s amp by the Dutch company and for some reason they ain´t regarded being all that,which from many an aspect is a downright shame.
Nevermind the color of it..just look at the design.
The imperative part of it though is the irons..which is of downright great quality.
So. Picked this bad boy up and to state that it had seen better days would be fair. To add insult to injury it was downright covered in dog hairs,nicotine and what not within. To the point where a god damn comb was needed more then anything!
6411 means 4pcs of EL-81 which IMO is a really underrated tube. An old so called "line tube" with its plate conn at the top of the tube. Philips at the time quoted these amps at 40w clean and i see no reason to distrust that number.
Now. However,what IS garbage is them black tar capacitors. To the point that there´s no point what so ever even checking them. By now the ONLY way for those suckers is the bin and done deal.
The electrolytics however...were fine! No wonder,they were of Swedish Rifa brand. Rifa electrolytes are simply world class stuff gents...that simple.
Well. As you can see i tossed a couple of fresh coupling caps between the powertubes and PI as the ones in there leaked like crazy,of course,to be able to fire the thing up at least.
It fired up alright and indeed..voltage was down. No wonder seing that the rest of them caps were still in there. What´s more several of the resistors were shot as well.
So. Per usual i guess. Clean slate. Fabbed a block off plate for the rear facia out of anodized aluminium...a cut out for an IEC jack and in turn a few fuse holders.
Tubes of this thing,apart from the EL-81´s,are ECC-40´s and EF-40´s. ECC-40 the forerunner for ECC-83/12AX7 and the EF-40 the same for EF-86. To the point where the MAIN differences are different socket/pinout and what´s know as gm,or transconductance. That´s about it tho. The sockets for the older tubes are what´s known as "rimlock" ones. Google if you´re curious.
No matter,what i´ll "save" is one of the EF-40´s. Might be a cool tube for SnG. What´s more they´re around in abundance and costs of nothing to replace (same for EL-81´s btw).
But of course...
The chassis indeed had seen better days to i tried attacking it with some fine grit steel wool. That didn´t do it though so i stepped up to 400grit wet. Way better.
As the "hood" of this thing basically covers the entire amp i see no real reason to paint the chassis too.
Atop that various pieces of the wiring was replaced as well.
The old "radiator" style rectifier bridge was retired and a fresh silicon one installed directly to the powertransformer lugs. The stocker being as large as it is...talk about saving space!
In turn that board there was put together to cater to negative bias voltage.
Then. These amps use a "half tap" for the HT winding and as the full winding is rectified and have smoothing caps installed this half tap is used to run the powertube screens,then at approx half the full B+ voltage.
A jump forward for today then. Things are coming along nicely i´d say.
What was needed for the powertubes was installed in this manner. Sleek and effective. The two wires from the bias board of different colors as that makes it way easier to take to heart which pot leads to which pair of powertubes.
As i fired the thing up first time out,still with the "radiator" rectifier bridge,B+ wouldn´t even touch 300VDC....now we were seing an EASY 360VDC+ @30mA a powertube. That´s one major difference for ya!
For some reason though from a hum perspective the powertubes were really anal about side to side balance.? Hm..guess i need to look into that.
When it came to the PI i reused the stock solder support,just placed it elsewhere.
Then for the preamp. Gonna try a few different trix this time out. Gonna be interesting to see the outcome of those.
Now...if you DON`T know what you´re doing this can certainly become life on the wild side. The bracket there is one of the stockers and i came to "massage" it a little bit to make it fit that there electrolytic,which is the last in the preamp row. Even a minor dent makes the e-lyte become scrap in my book so...
The bias board then. Nothing all that much sexy about it i guess. Bias voltage tho,as it turns out,almost knocked on the door of minus 30 volts DC to set the powertubes where they need to be. Take into account the 360VDC+ B+ and then 180VDC+ for the screens...them almost minus 30 is a rather tall number.
´Nnnnnnn here we go. Sure enough,doing what it´s supposed to. Voltages ended up just about on par as far as what i want out of it.
"Hood" got yet another few coats of red and TBH? Not all that shabby huh? Now for the install of the Philips "hood ornament" and then a few coats of clearcoat to make the whole thing stand out.
What remains to be done isn´t all the much really. I´ve gotta build a tonecontrol...and install a few wires,but that´s about it. Most of the signal wire is already installed,down to the PPIMV stuff.
In short?
This one´ll start roaring its heart out as of tomorrow,no doubt.
