Italian tubers

Burns, Selmer, WEM, and more

Italian tubers

Postby Racing on Thu Feb 02, 2012 1:07 am

Up here in Sweden Albin Hagstrom Inc imported some budget valve amps back in the -70s under the name DNS. DNS for Denmark,Norway,Sweden.
It has come to my attention that these budget amps were marketed elsewhere under the name of "Sound".

I´m currently reworking a DNS Special 60 RT. RT for reverb&tremolo.

These amps are built a little different from most in as much that they are made up from 3 major parts. The pre-amp,the reverb tank and the powerstage.
From a quality POW i´d say that the electromechanical pts are just plain rubbish.Novalsockets,pots and jacks needs to be replaced. Easy and cheap enough i guess. Then...the PCB is often warped from age and that brings that the copper layout is often ruptured. Again easy enough to remedy by just bolting the PCB to a piece of aluminium sheet metal and thereby forcing it level again.

It sport a plethora of tubes though. All in all 5 within the pre-amp and then one noval as PI and ends up in a quartet of EL84,s out back. Having played around with the design for the better part of a week now i have to say...when one rethinks the whole setup it isn´t without merit TBH.

OEM they carry basicaly two separate pre-amps and what i´ve done is to put these in serial instead of para...and that in turn has brought forward some serious gain capacity.
Then,a mod to the concertina phaseinverter to get rid of the harshness of the OEM setup and in turn a redesign as far as values to make it run an ECC83 instead of an ECC82.

Seing the slim 4pcs EL84s i have to say that this is a rather loud MF.

As the OEM piece sport slider volumeadjustments i opted to make a new faceplate for it out of anodized alumnium.

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That much for DNS/Sound. Come late this week,or weekend,i´m going to take delivery of yet another old italian amp. An FBT500R2. Btw. Schematics are readily available for both of them.


That said. Anyone else out there with any info or knowledge on these old spagetti amps?
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Re: Italian tubers

Postby Racing on Tue Feb 07, 2012 2:13 am

Took delivery of the FBT.

Looks like this;

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Basicaly a bass amp,but seing its vintage same same kinda...

Wired PTP and as with the DNS i speak of above the powerstage and the pre-amp are separated.

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This then being the poweramp and powerstage.

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...and this being the pre-amp. Powertubes are oddball EL503s. PI an ECC82 concertina setup and the pre-amp is a pair of ECC83s.
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Re: Italian tubers

Postby Racing on Fri Feb 10, 2012 12:27 am

One now resurrected FBT 500-R2.

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Esteticaly parts have been chosen to keep within realms of the OEM piece,not so from a sound capacity POW though where this old warhorse now is WAY more rock and heavy metal than anything else.

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Here the very very "larger than life" sounding,and as obscure and expensive these days,EL503s with their OEM retainers in place. What started out as a rather mundane old late 60s bass amp has turned into a downrigt 4 gainstage screamer. :mrgreen:
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Re: Italian tubers

Postby Racing on Fri Feb 10, 2012 7:31 pm

The by now heavy metal rig... :mrgreen:

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Looks....can indeed be decieving... :twisted:
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Re: Italian tubers

Postby Racing on Sat Feb 11, 2012 9:55 pm

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Re: Italian tubers

Postby Racing on Sun Feb 26, 2012 6:14 pm

The idea of the FBT above was to create a hotrod. Much like running around with an overly souped up engine is an econobox on regular streets. As these FBT;s were delivered back in the late -60s they weren´t really all that contemporary sounding vs for instance the plexis and what have you not seing the time n age.
Ambition was clear. An old n sorry looking amp setup for heavy metal.

Handled by friend Daniel...axe is an 1980 vintage Aria Pro II LS-800. Stock pups,which are like a pair of slightly overwound PAFs. That aside,axe-hose-amp. No nonsense and no effects and no editing. This is straight out of the DV cam.

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Re: Italian tubers

Postby Racing on Thu Mar 22, 2012 10:11 am

Well,whatta ya know...scavenged another two that are going to be modded according to the same template.


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One of them being the same bass version that i modded already and the other one being the trem n reverb model.
Regardless they´re going to be setup the way the last one was,to in essence make them way more contemporary.

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OEM the bass version is as basic as they come. Three meek dials and that´s it. OEM they are stiff sounding amps that basicaly can be mustered to some sort of clean,and that´s it. Seing how they´re setup i guess it´s no surprise though. OEM they simply sound bloody awful. That aside however they are extremely well built point to point units basicaly making for an amp modders dream.

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Might look like a rats nest but in reality it is not. Just the angle that makes for the somewhat..crowded impression. Layout is both logical and straight forward. Easy to understand.

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..and here we got the powerstage part of these amps. As mentioned the EL503s and an ECC82 for PI. Concertina PI with driver-hence the use of an 82.
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Re: Italian tubers

Postby Racing on Sun Mar 25, 2012 3:47 pm

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´N here we go all over. Another one of these modded to put out a more contemporary sound. :mrgreen:

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..then a friend stopped by with this...which is going down the same route. They really DO sound bloody awful stock.
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Re: Italian tubers

Postby Racing on Wed Mar 28, 2012 10:26 pm

So let´s keep pushin... :lol:

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Here´s the last of the finished 500-R2´s.....
This one even better sounding than the first,and to ad insult to injury No3 is in the works.

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Then for one basicaly finished 250. A cathode biased dual EL84 amp that is loud as HELL for its pair of EL84s...and basicaly transformed into a heavy metall amp this one too....

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Then on to this ugly duckling. Now..peculiar amp. In essence built "inside out" as you can see. It is an Eko Herald. In the works right now and has been handed an extra pre-amp pipe for an additional two gainstages.
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Re: Italian tubers

Postby Racing on Tue Apr 10, 2012 12:06 am

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Slowly approaching the stage where it´s done. Halfway loud "18 watter". Sort of.. 4 gainstages,inc the driverstage for the concertina. Only the first one carries a cathode cap,after that it is all "au naturel" and works rather well i´d say.
Loud enough for a fullblown band at least,albeit not with excessive headroom TBH.
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Re: Italian tubers

Postby PeterS on Wed Apr 11, 2012 3:28 am

Hefty looking trannies in that FBT.

A cathode biased dual EL84 amp that is loud as HELL for its pair of EL84s...


What's the plate voltage?
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Re: Italian tubers

Postby Racing on Wed Apr 11, 2012 12:14 pm

FBT states 350VDC but as voltage at the wall has changed somewhat up here since back in the day in reality we´re talking 360+. (We´ve gone from 220-ish to 240 sharp in the last 30yrs)

Screens in turn are quoted at 290,and seing the reasoning above it touches down at 300 even approx. IOW...it IS running the 84s on the jagged edge but it seems to work.

The 84s i tend to use are chinese ripoffs of the fabled 6N14P and those are some hefty 84s TBH..might be that. Never tried these machines with TADs,JJs or similar.
Them chinese 84s btw are recommended. They in short sound great and only turn better the closer to the edge you run ém-from what it seems.
Have installed them in numerous amps by now(we import them ourselves from china by the bundle) and so far we´ve seen a very minor few that has drifted.
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Re: Italian tubers

Postby Racing on Tue May 08, 2012 6:49 pm

Them FBT 500-R2s are gettin popular i "Racing" trim.

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So next one up showed today. Gonna rip that apart and copycat what´s already a working concept. They ARE ugly tho!!
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Re: Italian tubers

Postby Racing on Sat May 26, 2012 6:00 pm

Update time.

That last FBT kind of got done. As it is intended for a friend of mine up in stockholm the faceplate got a somewhat...different layout :mrgreen:

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As is the cab got a new baffle and some fresh Eminence gov´n;rs installed. Net result is about on par with the others i´ve made.

Then...as this thread started out with this old POS DNS...and the preamp PCB was warped to kingdome come...i kind of set in on hold for a while. Then another cust of mine came in the door with this blown up old Kustom quad transistor combo.
So. Said n done that combo was gutted for the benefit of having the old DNS powerstage/trafos installed. Then...i opted to build a completely fresh preamp from scratch. A 2 channel one mixed "the old way" via a pair of 220k mixer resistors just upstream of the mastervolume dial.

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The OEM Kustom steel chassis was utilized as chassis for the fresh build too,just that i cut a fresh faceplate for it.

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Indeed.... :lol: :lol:

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A few purely estetic details remain,like cutting a fresh front emblem for it out of stainless asf,but as a whole it is working and rather well at that. The normal channel is a two stager with a 150k anode,3.3k cathode and a 47uF cap across that for the first and then 100/1.5/22 for the second. Lead in turn is a 4 stager of more complex build that was setup to cater to stringseparation and luster albeit ample amounts of gain.
FWIW,on a different note,if you run into a bombed out Kustom quad DO give it a new home. The point being that the cabs are well built and sports a rather well sounding Celestion super65.
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Re: Italian tubers

Postby dread_lion on Tue May 29, 2012 6:14 pm

Did you actually try out FBT trem/rev model before modding it? I just recently restored one, and it blew me away sound wise!
I decided not to mod it, and keep it original, as this thing really sounds very, very cool!
It did have a few bad parts, but after changing these, these amps can sound wonderfull.

Luckily for me, its not THAT hard to find used EL503's. I see them online from time to time for about 40 euro a piece. Not bad considering a few years ago, you still needed to pay around 150 for a new one. Anyway, these tubes will last almost forever, so if they are good, dont touch them!
vintage baby
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