Italian tubers

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Re: Italian tubers

Postby Racing on Sun Mar 10, 2013 8:14 pm

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Scrapped the rather useless reverb,kept the tremolo. Turned the preamp into a single channel 4 stager and remodeled the PI into a LTP instead.

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The PI conversion meant that i recycled the tagboard from the reverb setup. In turn i opted to install a master and a PPIMV both. Useful to say the least.

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Remains to clean and refurbish the cab. All in all though this kind of came to be a natural evolution of the series of 500s i´ve built.
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Re: Italian tubers

Postby dread__lion on Sun Mar 17, 2013 9:33 pm

awesome work! as usual. Do you ever get any sleep? :p

anyway, i've got a question for you! I have these transformer sets lying around from a 200 watt Faylon guitar amp (made in Belgium, where i happen to live).
I was wondering, if i could use these for a 4xEL34 amp? they seem pretty robust and i have read a few stories about succesfull conversions.
Here is the schematic:
http://elektrotanya.com/PREVIEWS/63463243/23432455/oldies/egyeb/faylon_power-200_audio_pa_1973_sch.pdf_1.png

the PT reads 390VA and the OT has 4, 8, 16 and 32ohm outputs. i calculated and measured 2,150kohm primary by the way
I can build an amp no problem, but numbers where never my strong point. i keep looking at datasheets and get confused. I'm guessing i just need to rewire to a difference output for the right primary load on the EL34's? how about the PT? will it hold up?
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Re: Italian tubers

Postby Racing on Tue Mar 19, 2013 1:26 pm

390VA will suffice and then some!!! That is one serious PT imo.

As for measuring OT impedance,google and read up online. Easier than me writing half a book on the subject,no offense.
But yes. You´re most likely homefree on both counts.

As for the 503´s(OEM Faylon schem),not tellin you what to do..but they CAN be had for rather reasonable money via german e-bay. Around there they´re still plentiful. Likewise with magonval sockets.

EL34´s...feels kind of mundane doesn´t it?

Then there´s always the 504´s...also cool tubes. Have to say that in that last Klemt build of mine they impressed the living crap outta me. Fugedabout the wattage...i´m talking sound here.
That Klemt B30 is nothing short of a crude,old school sounding,marvel..
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Re: Italian tubers

Postby dread__lion on Tue Mar 19, 2013 2:35 pm

Thanks for your fast reply. I guess I'm most worried about the extra current draw on the heater windings.
I even thought about a 4x kt88 amp, trying to reach 200 watt. The iron is unbelievably big and heavy lol. I see your point about el34 being a bit mundane. However, they're are so many choices of cool amps running el34's and they are available cheap and easily, and will be for a long time. Anyway , haven't decided yet.
What do you think about the 4xkt88 plan? Will the extra current on the filament winding overload the tranny? Or should I not worry about it with this pt? That would make a bad ass amp!
By the way, I don't have 1 but 2 of these sets trannies. I will upload some pics later tonight!
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Re: Italian tubers

Postby dread__lion on Wed Mar 27, 2013 8:21 pm

Sorry for the late reply! I've been super busy. Here are some pictures from the output transformer next to a deluxe output transformer, so you can get an idea of the size. I've compared it to a 100 watt 6L6 amp. The power transformer is only as big as the 100watt pt but the output transformer is about twice as large as the 100watt output transformer.

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so i'm a bit worried about my KT88 plan, not sure if they would handle it.

Ow yes, i also meant to say, i played a bit more with my FBT500 amp, and i changed my mind, you are quite right. The amp sounds completely boring, has no warmth or depth to it. It could almost of have been a solid state amp. So i'm going to try a few mods you suggested!
I would love to hear your thoughts about the transformers. If i cant make it work with KT88, i'm thinking about building something along the lines of matamp/ early orange amps!
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Re: Italian tubers

Postby LuciMan on Thu Mar 28, 2013 9:34 am

dread__lion wrote:..... a 200 watt Faylon guitar amp (made in Belgium, where i happen to live).

.... where I happen to live too! :D (flamish or french or german?)
dread__lion wrote:I was wondering, if i could use these for a 4xEL34 amp? .....

I'm afraid you can't. 4x EL34 need 1,7 KOhm - 4x EL503 = 1,2 KOhm

dread__lion wrote:the PT reads 390VA and the OT has 4, 8, 16 and 32ohm outputs. i calculated and measured 2,150kohm primary by the way
I can build an amp no problem, but numbers where never my strong point. i keep looking at datasheets and get confused. I'm guessing i just need to rewire to a difference output for the right primary load on the EL34's? how about the PT? will it hold up?


The EL503 (which is very expensive these days) is a Beam-Power-Tube with lower voltage but higher current and can't be replaced bei a EL34. There were some adaptions done (EL504 etc ...) but I wonder if it's worthwhile.
I did a 4x EL503-amp 80 Watt in 1973 (when they were cheap) and I still have the same set of PT ( 1x 220V- 0,7 A) & OT (Raa 1,2 KOhm) for the same schematic here waiting for a task. Btw - these PT & OT are big too (M201b)!

I wonder if 6x EL34 could do the job - at least it's not such a big mismatch. I already tried to double the PT sec-voltage (cascade) for EL34 which worked fine. But I never built up the amp.

Why don't you use these EL503? Are they dead? Just change the preamp-schematic to something different and you're done.

Cheers - tot ziens - à bientot - auf Wiedersehen!
Vox (Clones): AC3 TB (ex-SuperTwin '81- Rose Morris); AC10; AC15; AC30/4; AC30/6 TB (rear); AC30/6 TB Reverb
Dynacord: MV46/Exquisit/Eminent EMT/Echocord S62a/Bassking (black & silver)
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Re: Italian tubers

Postby Racing on Thu Mar 28, 2013 12:34 pm

I have to agree.
Give them EL503 half a chance to prove themselves to you..

As far as deadly expensive..nah. Check german e-bay. They can be had for reasonable money and them old NOS tubes SURE are of way better quality than anything made today. Ie;they hold up like forever.
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Re: Italian tubers

Postby LuciMan on Thu Mar 28, 2013 4:24 pm

Racing wrote:......As far as deadly expensive..nah. Check german e-bay. They can be had for reasonable money and them old NOS tubes SURE are of way better quality than anything made today. Ie;they hold up like forever.


I do it every day because of my NOS PT & OT for 4x EL503 (Radio RIM Musikant, Germany).
Look for yourself EL503. The same amp I built in 1973 (Musikant 4x EL503) went up to EUR 216,- .

"reasonable money" means something different to me. For that kind of money you can buy EL34 - PTs & OTs . :wink:

Anyway -if the amp is working properly and it's only a question of sounding .. no unsolvable problem!

Cheers
Vox (Clones): AC3 TB (ex-SuperTwin '81- Rose Morris); AC10; AC15; AC30/4; AC30/6 TB (rear); AC30/6 TB Reverb
Dynacord: MV46/Exquisit/Eminent EMT/Echocord S62a/Bassking (black & silver)
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Re: Italian tubers

Postby dread__lion on Thu Mar 28, 2013 8:37 pm

ok, first of, welcome to this thread luciman ;). I'm from the Flemish part by the way, but i speak french rather well!

Anyway, back on topic. I think i need to make myself a bit more clear. I have 2 power transformers and 2 output transformers, that belonged to that faylon P200 amp. I do not have the amps, i do not have any other parts than the transformers. I got them in a trade, with 2 EL503's, wich are currently in my FBT 500, and they are not moving out of that amp, its was my uncle's amp when he was younger, so its a personal thing.
Anyway, so i have these huge lumps of iron hanging around. I have absolutely no intention of buying 8 EL503, wich at the best price i can find them (40 euro a piece for used ones) would still cost me 320 euro's for the tubes alone, without even having the right sockets.
Since i only have the transformers, i want to use these and build something different with them. I agree that you should not do this with working amplifiers, and i would not be a fan of doing such things. But no-one is interested in parts for Faylon amps, so i figured i might just do something with them.

now if someone could just tell me if 390VA is enough to get 4XKT88 running, i would be a happy man ;). Also, i'm pretty sure the primary of these transformers is 2,150k, since i measured this with a signal generator putting out 1v 1khz signal, and calculating the ratio and so on. as stated before, i'm most worried about the heater current draw being much higher!

some more pictures to clarify things!

Image

Image
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Re: Italian tubers

Postby LuciMan on Fri Mar 29, 2013 10:53 am

@
Ik ben en Duitse en woon in het duitstalige deel van België (Drielandpunt). Vlaamse kan ik begrijpen, maar niet spreken. Frans gaat zo la la. :)

Now we know how the situation is. You've got two PT an two OT. I wonder which combination of tubes one can use in the 2,15 KOhm-area.

But the OT can be used I guess, but I wonder where the 390V AC comes from. The schematic shows different: 480V AC. Anyway - 390V AC gives you about 540V DC which can be handled by KT88. As the EL503 works with higher current than the EL34 etc., it will be sufficient (at least 0,6A I presume).

Cheers

Edit: corr.
Vox (Clones): AC3 TB (ex-SuperTwin '81- Rose Morris); AC10; AC15; AC30/4; AC30/6 TB (rear); AC30/6 TB Reverb
Dynacord: MV46/Exquisit/Eminent EMT/Echocord S62a/Bassking (black & silver)
Burns: 40th Anniversary Hank Marvin Signature, white / Double Six, redburst
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Re: Italian tubers

Postby dread__lion on Fri Mar 29, 2013 11:21 am

Hey luciman,
Das ist toll!
My german isnt that good, but i can understand it allright!

Anyway, the transformer reads 390Va not Vac ;). So it indicates the power handling rather than the voltage! However, el503 have a heater current draw of about 0,9A vs kt88 draw about 1,5A for a kt88. Thats the thing that worries me the most! I'm also not really that good in calculating the total wattage needed for a 4xkt88 amp.
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Re: Italian tubers

Postby Racing on Tue Apr 23, 2013 8:09 am

Don´t be so fast to rule various powertubes out i say. Be aware that what runs for the nodes and what runs for the screens are two different things.
Ie;by keeping voltage for pole 4 of a regular EL-34 down for instance rather elevated voltages can be run for the nodes at pole 3...

Yeah.
I still find EL-503´s to be reasonable. Put it in perspective. Them old -60´s tubes were made with a completely different attention to detail than what´s being made today ..bringing that you don´t exactly replace old -60´s tubes on a day to day basis. The difference in lifespan is like night and day even.
Seing that..and doing the math as far as penny/hr...nah..i don´t think EL-503´s are all that expensive. I certainly don´t.


That said. Let´s kill a myth as for what "can and can not" be done right off the bat shall we?

I ran into yet another two FBT-500R´s.
Both of which had been "modified" for EL-34´s previously...and for a friggin hackjob TBH. Isolation of various point by the use of common tape.. :lol: . The OEM loop between the screens and nodes still in place...total lack of screen resistors making the 34´s basicaly run in triode mode..

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So. I set out to tidy it all up. FWIW...one piece of the FBT circuitry that doesn´t show in the schem is that there´s a couple of ceramic resistors on inbound B+ right after the two diodes (the machine runs with CT). These are of 4,7 Ohms a pop,and i presume they´re there to limit inrushing current on startup. I´ve come to omit these...and the whole thing works as good as ever.

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One of them sported old Philips Miniwatt metal base EL-34´s...

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..´n the other 6CA7´s

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Heater wiring was chafed and burnt all over so i installed some fresh...twisting it at the same time. PI´s were reset from concertina to LTP,and at that with the extra caps needed to run....

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...a PPIMV.

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At that 1k ceramics were added for the screens and referenced 1 Ohm resistor were added as bias measuring points. Asf asf asf.

Now.
If you run the numbers the OEM OT of these sport 2,6k impedance. Add to that the rather mellow ~400VDC under load and it turns out that the OEM OT will work. Yes...we´ll be a FEW watts short,all good,but it WILL work.
´N true enough..
I got to try both the powerstages yesterday after resto/modding was done..and yep. Runs as well as ever. The few watts missing (i came to the numer 5w total) you certainly won´t hear or miss...

Come today,if i get the time,i´ll start out building the preamps.
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Re: Italian tubers

Postby dread__lion on Tue Apr 23, 2013 11:13 am

Hey racing, as usual, cool amps and thanks for the information. I appreciatie your opnion about the el503's and would like to experiment with them more. However, the fact is, i dont have the funds nor the needs to build 2 4xel503 amps. I do however have a bunch of el34's lying around, and i would love to build an orange inspired amp. So i think i'm going to use these transformers for that. My original plan was an amp running 4xkt88 but i think that that is a bit ambitious with theae trannies, if i compare sizes with a kt88 transformer, these are way smaller.
I do completely agree on new vs old tubes! Thats why i would prefer a el34 amp, old el34's are cheap and easy to find, and i l've got quite afl few lying around!
Your point about long term is well taken though ;).
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Re: Italian tubers

Postby Racing on Wed Apr 24, 2013 7:52 am

I hear ya.

Image

At this end we´ve got ourselves a roaring 4 stager since yesterday. Works as intended..need to tweak it a bit though.
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Re: Italian tubers

Postby Racing on Wed Apr 24, 2013 10:55 pm

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One down...one to go.
Works as a 4 stager with a master and PPIMV,and works as god intended. Loud as crap too,so that much for the difference in OT impedance.
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