Italian tubers

Burns, Selmer, WEM, and more

Re: Italian tubers

Postby Racing on Sat Apr 27, 2013 9:48 am

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´N yet another one done. After a few tweaks a really wild sounding amp i have to say!
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Re: Italian tubers

Postby Racing on Fri Jun 28, 2013 12:40 am

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A rather obscure old Italian build. A Mac 2C. Twin EL84´s at rather sharp 400VDC. Transistor entry stages for some reason. Trem and reverb..
Dunno what to do with it yet.
Moved the centertaps a bit so they hook up at the first e-lyte. Made the amp way more silent as far as hum n hiss..
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Re: Italian tubers

Postby Racing on Sat Jun 29, 2013 11:46 am

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I was wrong. Upon closer examination of the amp it turns out that the two smaller novals are the PI,as in driver and a concertina,and the tremolo. Thing being that the tremolo works but isn´t especially active

As noted it is a dual EL-84 amp,and as it shows a hybrid one. No wonder it sounds so-so. The main entry amplification being from rather small PCB´s mounted directly to the inputjacks.

The amp´s got a "guitar channel" and an "organ channel". The latter being of higher amplification factor than the former.

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All e-lytes are italo typical Ducatis. In this case in turn they seem to be ok :shock: ?

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PCB´s for the EQ is hooked directly to the pots. On the other hand..them PCB´s ain´t overly large in any way so...i guess it´s all good. Haven´t looked into what kind of stack is used yet.

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Amp is run with fixed bias stock. A 47k resistor vs ground and all of that....so while i replaced the e-lytes for the bias circuit as well as the transistor ditto i opted to modify the amp for adjustable bias voltage. A simple 47k trimpot in series with a 15k resistor. Worked as anticipated.

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As i got her up n running i was kind of the notion that the mere size of the combo made the entire proposal rather...silly. A mere 18 watts out of that overly huge cab was kind of ridiculous.
Did some measuring on the trafos,both,and it soon enough turned out that my suspicions were correct. Mac had used the same hardware for the 18w and 36w units both. :D
Provisions were already made on the PCB...so why the hell not?
Sure enough...a matched quartett of EL-84´s later we had ourselves a way more loud amp.

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That of course brought that a few points needed to be altered as far as topology of the PCB. Pulling that off coupled with that the amp most likely hasn´t seen any service or cleaning in the last 40yrs...rubbing alcohol and a brush...
Screen resistors were OEM of 330 Ohms. Drop resistor between OT center and screen tap was non existent....so i opted to install 470 Ohm screen resistors and a 330 Ohm drop ditto. The latter still to be installed more permanent.

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So. The concertina was scrapped and replaced by a LTP instead. This..cause of upcoming plans for the amp.

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One of the e-lytes i took out was stamped 9/69 which i presume brings that this amp was made in 1970.

So.
What up? Well...it sure doesn´t sound a dogs dangly bits as is,so that needs to be adressed. Many of these old early hyrbid amsp leaves something to be desired from that aspect IMO.
At the same time i don´t wanna ruin the amp per se,so i´m currently giving thought to use a free space up front to install a card...and a few novals.
We´ll see where it all ends up.
Hopefully in something WAY more useful for modern sounds than OEM at least,and then still with an easy option to reverse to original should the will ever arise. Ie,a non intrusive setup.
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Re: Italian tubers

Postby Racing on Mon Jul 01, 2013 5:44 am

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Fabbed a real simple tagboard with a couple of novals to it. The idea here being a "2203 setup". Ie,first channel running two of the triodes,and then the second channel running into the first for a total of 4 triodes.

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A tagstrip and some e-lytes to control railvoltage for the preamp tubes.

The thing is that with the amp up and running with 2 powertubes alone set to oorrect bias B+ voltage came down a little. Approx 390VDC. The add-on of of the extra two EL84´s made voltage drop to approx 385VDC. Iow the trafos indeed are on the large side.
The extra two novals in turn made B+ voltage end up at 375 approx.
(MInd you with the drop resistor between screens and PI reduced from 10k to 820 Ohms to inrease voltage at PI which was stock approx 300 and now 355)

I still had issues with slight hum though. Scratched my head to no avail and tried various different ideas ´til i just for S n giggles installed a fresh 47uF axial across the first hit...silent.
Turns out that the OEM Ducati e-lytes weren´t all that after all. :shock:

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..so out they came..

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´N the whole thing came to look like this instead as i had axials around.
The funny thing with that was that as i got to redo the chassis grounding amongst other voltages of the entire amp jumped a little. Ie;all of them. That in turn reduced hum even more in turn obviously..one thing led to another and all of a sudden i had myself a very well behaving amp.

Remains to hook the signal up to the tube preamp... The thing is that the controls for tone and volume are active. Run by a BC147,and i dunno what to do with that yet. Debating with myself as far as if going active in this case really brings anything to the party.?
If not i´ll scrap the active setup but keep the PCB for them and just route it as a James per channel and be done with it already.

Further the amps shielding needs to be improved upon. By the use of coax wiring and install of minor sheets of metal here n there to reduce the chance of interference.
If i opt to go "2203" even more so..
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Re: Italian tubers

Postby Racing on Wed Jul 31, 2013 10:32 pm

Lot of time n effort has been spent,and we currently have us one rather well performing old Mac 2C.
Or more to the point what´s left of it.

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This is a rather large combo about the power of an AC-30 now. Twin channel-and works per above.


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Then i ran into yet another of them DNS 120 Supreme. To the rest of Europe known under the label "Sound" as noted previously. This one in a rather sorry state from an electrical POW,but on the other hand in rather nice nick from an estetics.

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Was in dire need of service as far as e-lytes,powertubes asf. Measured ripple at first e-lyte as was and that amounted to approx 75VAC!

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Apart from modifying it to cope with more modern standards as far as sound i also spent some serious time getting it silent in idle. Whole thing worked out ok and i´d go as far as saying it´s a studio amp now.
Equipped with a "master" for the PI and a PPIMV too. These uses EL-504´s and apart from being rather cheap to dig up to this day them EL-504´s turn insanely loud as voltages for them go up.
One of these with a mere pair of 504´s will to the letter bury a standard 50w Marshall any day of the week.
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Re: Italian tubers

Postby peter horvath on Thu Aug 01, 2013 4:51 pm

I dig that Mac combo. Nice resurrection job! What I think MIGHT be the head only version of that amp shows up on eBay every so often - seller is Incarante(or was, at least). Now that I think of it, there was never a SS preamp mentioned, so perhaps it's all tube? Not sure...

Anyway, keep 'em coming. I enjoy your pictorials.
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Re: Italian tubers

Postby Racing on Fri Aug 09, 2013 2:02 am

Tnx Peter.
Lately it´s been a lot of back n forth how to handle the need for some 20 odd volts or so for the transistors to drive the reverb et al of the Mac combo.
Might very well be that i equip the amp with a transistor powered loop while at it. Thinking being that the very small PCB´s that OEM are installed to two of the input jacks might be put to good use that way.

The DNS i´ve mainly just used a bit since completion. TBH though,it being a "mere" twin twostager,i find it lacking overtones. Now,the thing with that is that DNS in their wisedom used a noval to hook the preamp unit up to the powerstage unit thereby really already providing for yet another noval should the need arise,and...as is i really am giving that some thought.
Brings that the wiring needs to be moved a bit and a fresh male and female socket be installed. Just as well maybe as the wiring in no way is locked in place to begin with.
We´ll see where it all touches down.
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Re: Italian tubers

Postby Racing on Thu Sep 12, 2013 12:05 pm

A short clip of the latest DNS 120 (which are known as "Sound" amps to the rest of europe).

Due to the p-poor Zoom Q3 used the volume is rather low in the clip. Approx 70dB+ or so.
Hum heard at the beginning isn´t the amp,it´s the lights in the shop.. :mrgreen: (it was built back in -31..)

http://www.youtube.com/watch?v=sZiVxEpyza8&feature=youtu.be

Anyways. That there is a modded DNS120. Intact with tremolo and reverb and i hope you bare me being tutorial in Swedish :lol: .
This is an amp aimed at "old school" rock and bluesrock. Still a dual channel twostager,and with added master as well as PPIMV pots out back.
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Re: Italian tubers

Postby donner on Thu Oct 31, 2013 3:30 pm

I have a small SOUND combo (2xECL82 +ECC83 Tremolo). Maybe an earlier version of the "Studio 10" as posted before. But mine has no model name written on it.
It has nice distortion at max. vol and through an external 2x12cab it is loud enough for jamming. Wish it had reverb.

Is there any more information about the SOUND company out there? Any product brochures?
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Re: Italian tubers

Postby Racing on Mon Nov 11, 2013 12:51 am

Not that i know of. No.
Up here the importer was Hagstroem when it comes to the Sound/DNS amps. That´s about it. At the time they were marketed as sort of an offspin of the -60´s era hype on Italian electronics i guess.

That said let´s climb the ladder a bit when talking Italian amps of the time. Let´s talk Geloso.
LOTS and LOTS can be read on Geloso online but one thing´s for certain,cheaply built amps they´re not. In fact i´d go as far as stating that from a tech/build quality point of view it´s about as good as it gets.

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So i picked this Geloso 3115-A up via German e-bay dirt cheap right. In essence a tube rectified "18 watter",and as can be conluded from the pics in the best of nicks. Just about looks like it is new...

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Albeit a rather "simple" amp it just reeks of quality. Oddly enough the first "micro" entry preamp stage can be loaded with two microphones at once. Nope..not separate channels. The phono input in turn just engages later in the circuitry.

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Clean is the word i believe. One EZ-81 and twin EL-84´s. About as simple as it gets..

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Albeit clearly marked Miniwatt they at least used to carry Geloso stickers too. The EZ and the preamp tubes still does.

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Yep. A Mini and an RCA clearly marked Geloso too..

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Do you notice a theme here? :mrgreen: Although cooler than snot it still is a mere 2 prong cord so it had to go.

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From the onset that grommet was sort of a hollow rivet with rounded edges. Sorry to say it was to narrow to fit a modern day n age 3 pronger,so i removed that "rivet" and installed that rubber grommet instead.
´N just look at that voltage selector.

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Layout within is simple and to the point. The machine non the less is old and when i first fired it up i had a B+ of approx 300VDC. As i swapped the main lytes of the amp B+ all in all climbed to 340VDC sharp. Good enough to go in short.

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Same goes for the eyelet board. It´s simply to the point and done deal.
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Re: Italian tubers

Postby Racing on Wed Nov 13, 2013 12:36 pm

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The 140w Geloso G1.1110-A came in the door. No way near the nick of the 3215. After a few hrs time though it came to life. Cleaning the innards up after som Mr Handyman... (like main e-lytes twisted in place with regular wire-cool at the housing of the wire is the negative of the lyte in case).

Anyways.
A 1110 is a LOUD MF.No argument there.

Spent some time with the 18w 3215 and have to say i´m duly impressed. It is one serious build boys. Redid the entire front end and remodeled the PI into a LTP. Installed a PPIMV.
With the PPIMV set to full blast and the gain and volume knobs set precisely half ways you to the letter have to look at the pilot light to know that the amp is running.
Someone at Geloso knew their stuff. Beyond a doubt.
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Re: Italian tubers

Postby Racing on Sat Nov 16, 2013 12:45 am

That minescule little 18w Geloso....

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It IS small. As in REALLY small.

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That there is my Pitchblack stagetuner ontop.

Might be,but this is the little engine that could see...

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Yep. It got handed yet another two pots. Them constitute a James.

So?
What it sound like? Well...my thought was to aim it for old school rocknroll right so we´re at two mere gainstages and a PI heading into a pair of fixed bias run EL-84´s.
A work in progress,cause it aint done. Yet.

http://www.youtube.com/watch?v=GaAi5veZSg8&feature=youtu.be

Friend Tatu abusing an Epi paulie...so yeah. That old Geloso´s got a new lease on life :mrgreen:
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Re: Italian tubers

Postby Racing on Sun Nov 17, 2013 6:53 pm

The larger 1110 Geloso had certainly seen the expert hands of Mr Handyman.

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As the two RCA plugs had been deleted the holes were enlarged in the most rudimentary of ways. Looked like Mr Handyman only had a rusty really dull file to use..Geez.. :roll:
So. I enlarged the two holes slightly yet to make a pair of regular washers fit and then welded them inplace with my TIG. Works i guess.

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The hood had gotten its fair share of abuse when in transit. Postal service don´t really deny themselves do they? So..hammer asf was brought out and..well..at least now the hood fits again. Going to invest some more serious time into making it shine further up the road.

As you can see the finish of the cab/chassis per se has seen better days as a whole why i plan to refurbish it when done with the electro/mechanical work.

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Then them absolutely fabulous EL-503´s! The retainers are off in the pic,but you get the general idea i guess. On sockets btw...these amps sport a sort of sprung socket suspended via a form of punched stainless steel. Works very well from what i gather.
The powertube magnoval sockets in turn are installed "floating" within their retainers. Yep...as always it´s all in the small details huh :wink: ?

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I opted to make the amp dual channel and in this case then one bass channel and one guitar. The layout differs acordingly vs stock. Separate stacks for each channel,while they both are James network setups.
The guitar preamp is driven harder and at lower rail voltage to produce a rather coarse grit sound-as far as distortion that is.

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Yep. As Italian as they come :mrgreen: . That aside i want to go on record and state that no matter what i´ve had my nose into on these two machines it reeks of quality.
Have talked to few techs that really have anything negative to say for these Gelosos. In short they´re rather high quality old PA units that can be found at really bargain bin prices and as such make for really valid foundations to build something of your own out of.

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Still looks a little clustered,i know,but that is due to a time limit set by that we had a half major gig last night and really needed a fresh serviced tube bass amp.
(FWIW i used the 18 watter above for guitar last night)

Got to try the guitar side of that 1110 out today and have to say that i feel it´s rather done. Distorts nicely,albeit the installed PPIMV really is needed to make this INSANELY loud amp useful.
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Re: Italian tubers

Postby Racing on Fri Nov 29, 2013 8:04 pm

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Re: Italian tubers

Postby Racing on Sun Jan 12, 2014 10:25 am

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Got me yet another Geloso. This time out a Geloso G1.1040
In plain english that means it´s a twin EL-34 amp. Diode rectified asf. Most likely from the end -60s. These amps are rather common around Europe and can be had at really reasonable rates.

Thus far what i´ve seen of Geloso impress me. Quality of the units are high and seeing what they go for that brings great foundations for builds of your own.
They are PA amps really,but that´s an easy remedy if guitar or bass is more of your game. The 1040 there i will modify into a two channel guitar amp of "old school" style.
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