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Old 16th June 2005, 05:36 AM   #1
karma is offline karma  Canada
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Arrow EL84 to 6l6

what im wondering is if i can replace the el84 with 6l6's and
would i need to replace the 0A2 rectifier tube's? i ended up geting two amps like this one in the pic big iron small power tubes.

just really wondering if the rectifiers need to be replaced and if so what make.

thanks..
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Old 16th June 2005, 05:38 AM   #2
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rectivier's
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Old 16th June 2005, 12:54 PM   #3
SY is offline SY  United States
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How much redesign are you willing to do? The 6L6 can run off the same plate load as most EL84 (8K p-p is most common), but it will require different plate and grid voltages and much greater drive voltage. Not to mention new sockets and more heater current, but that's the least of the issues.

Also, 0A2s are not rectifiers. They are voltage references, the tube equivalent of a zener diode.
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Old 16th June 2005, 05:26 PM   #4
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and who said you dont learn somthing new on the forum.
buddy said thay where rectifier tubes hmm i guese i should have looked them up .

first time i have ever ran into this type of tube.


i think what i will do is pull all 4 irons and start a 2 channel tube amp from the ground up. i meen if i have to retube replace caps
sockets and whatever.

i paid about $60 cash for the two amps i got kinda a deal
there hammond transformers.

let the fun begine


thanks..
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Old 16th June 2005, 06:51 PM   #5
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You may want to repaint the transformers as they seem rusty on some places.

This is a good starting point to a good stereo amplifier but don´t change the EL84,s for bigger tubes, the OPTs cannot handle the higher plate current and wattage.

Replace all the resistors and caps, they are old and will most likely fail anytime.
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Old 17th June 2005, 12:09 AM   #6
SHiFTY is offline SHiFTY  New Zealand
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If I were you I would stick with the EL84s, they are a great sounding output tube, that are actually not all that much lower in power than the 6L6. Remember that the 6L6 was a 1930s invention, whereas the EL84 was post ww2, with much better technology. 6L6s are kind of muffled, need mega drive to sound good, and consume heaps of current. EL84s can be driven fine by 12AX7s and are very efficient.

I would simply rebuild those amps as they are- EL84s sound better, look cooler and are cheaper to replace. Also the regulator tubes suggest regulated preamp / screens which is a fantastic idea. You might have some really sweet amps there- I agree you got a deal.

Simply replace all signal caps, all out of spec resistors and just use these as they are.

If you want some big fat tubes on there use 5U4G for rectifiers...

Just my 0.02.
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Old 18th June 2005, 07:07 PM   #7
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i have had a good look at it im going to save it. u can see in the pic there's 3 sockets open one for a 6AV6 and 2 for 12AX7.
im going to add another output transformer and put the 12AX7
ware the 6AV6 is and use the other 2 sockets for the EL84's
that would work. and it would give me a two channel block

would it not?

not sure ware im going to put the output tranny ill find somwarez.
the other amp was allready pulled apart when i got it. so this would be the cheapest way to go.

here is the listing the guy had on ebay.

As pictured – power amp from a 60’s spinet organ. Very nice cosmetic condition – was working when organ was de-commissioned some time ago. Organ amps often make good starting points for homegrown audiophile projects because their designs did not skimp on transformer sizes. Plus this one already has some control pots, RCA jacks and Amphenol outlets already cut into the chassis. Measures 15 ½” x 8” long and weighs around 10 lbs unboxed. Ultralinear output transformer.

Estimated power output for this is probably around 10 watts or so. If memory serves it was driving a pair of 8ohm 12” AlNico speakers. Utilizes a pair of 7189 output tubes – 7189’s are an industrial version of the 6BQ5 / EL84 and are capable of higher voltage across the screen and plate. Quite common among Fisher amp designs. The rest of the tubes required are two 12AX7, one 6AV6 and two 0A2 voltage regulators.

BONUS. All tubes pictured are included with the winning bid. If bidding tops $125 for this amp I’ll include the two extra xformers you see in the last picture as well as a pair of 12AX7 Bugle Boy (see my other auctions for the story on these). I don’t have the specs on the xformer marked Ultralinear but here’s the website reference for the Hammond 1608 push pull transformer . Will be double boxed for safe shipment – no extra packing fees. Bidding starts at a penny and no reserve. Good luck.

heh i got it cheaper with the extra part's
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Old 18th June 2005, 11:48 PM   #8
SHiFTY is offline SHiFTY  New Zealand
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Oh, ok, In your original post you said you had two valve amplifiers- I was thinking you had two "monoblocks" you could rebuild.

Seeing that you only have one, I would recommend rebuilding, remember that PP transformers designed for 2 tubes will not work with just one. So you will probably need 4 output tubes (el84s or 7189s)

One problem is that the power trans (designed for 2 7189s) may not be up to it- you might want to install a separate 6.3V filament transformer to take some of the load off.

You should go with a nice simple design, use silicon diodes for rectifiers even.

Something like the Leak stereo 20 as i mentioned before.
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Old 19th June 2005, 12:05 AM   #9
karma is offline karma  Canada
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well 1 and a half of the other ill try installing a separate 6.3V filament transformer see how it pans out

thanks..
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