Edrel's Irons

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Edrel's Irons

Postby brady » Sat Dec 03, 2011 3:33 pm

Just finished a friends 2A3 amp. Edrel Sison's irons all the way.

I sort of knew it was going to sound good (before we even started laying out the parts) but two nights ago, we finally had a listen and it sure sounded surprisingly good.

Circuit is very simple and straightforward. Morgan Jones' beta follower 6SN7 as voltage amplifier, capacitor coupled to a parallel 6SN7 as driver, cathode follower direct coupled to the grid of a 2A3. That's 3 or 4 stages in all. The use of the 6SN7 as driver was due to the fact that the owner had a lot of these and didn't want to spring for a higher voltage/higher current tube. At any rate, we paralleled the triodes to achieve lower Z out and higher I. Edrel's choke loaded the cathode. OPT primary Z is 2k7. An insane no-holds barred way over the top power supply. LCLC for ALL stages (in fact I just received the 60Hy/25mA choke a few hours ago. This will decouple/filter voltage amp supply from the B+ rail in lieu of the resistor now used)

We tried it through two cheap single drivers. Great both ways. Sometime next week (after we sort of cleaned up the wiring), we'll try the amp to drive a 2 and a half way horn --- Altec woof, Coral mids and tweets. We'll see.

I had two well known amps before (now dis-assembled and unlamented) and Edrel's was better. Two more amps coming in tonight. All more expensive. Heheheh.

Haven't run it through the o' scopes yet. Not yet anyway. I don't want my mind to be biased by what the instruments would tell me. heheheh

Thanks Edrel for bearing with us (I would very often text Edrel to change specs in the middle of the night... or send a spec no winder would possibly entertain - I hope there weren't too much magnetic wire unwound and thrown out :) )
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Re: Edrel's Irons

Postby tony » Sat Dec 03, 2011 3:57 pm

Hi Brady,

we were on the phone last night and Edrel mentioned you.....i guess we can let the cat out of the bag......the key to Edrel's irons is the tight winding geometry resulting to lower leakage inductance......and the use of nomex insulation tapes instead of paper as is traditionally used in older transformers.... this results in lower interwinding capacitance.......paper has no place in an output traffo.......except maybe as bobbins........ :D

interesting to find out your results with the beta followers, so you have outgrown that allergy to sand? ;)
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Re: Edrel's Irons

Postby brady » Mon Dec 05, 2011 6:00 am

"interesting to find out your results with the beta followers, so you have outgrown that allergy to sand? "

Hi Tony. Heheheheh. We even tried SS as drivers few years ago ala Jack E's 300B. TDA something. But we could not even produce an acceptable scope reading.

The 6SN7 in b-follower sounded "cleaner" than our earlier experiment with 6AU6. Or cascoded 6922.

I think the reason this specific amp sounds excellent is a very stiff, very straight power supply. And that became possible only because Edrel is patient... hehehehe
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Re: Edrel's Irons

Postby tony » Mon Dec 05, 2011 6:38 am

brady wrote:"interesting to find out your results with the beta followers, so you have outgrown that allergy to sand? "

Hi Tony. Heheheheh. We even tried SS as drivers few years ago ala Jack E's 300B. TDA something. But we could not even produce an acceptable scope reading.

The 6SN7 in b-follower sounded "cleaner" than our earlier experiment with 6AU6. Or cascoded 6922.

I think the reason this specific amp sounds excellent is a very stiff, very straight power supply. And that became possible only because Edrel is patient... hehehehe



indeed, making the power supply very stiff has lots of advantages.....i try to implement that in all my builds..... :clap:
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Re: Edrel's Irons

Postby brady » Tue Jan 03, 2012 6:49 pm

scoped the amp. just a resistor load (speaker Z varies with F)

flat up to around 50khz... then very slight sloping. At the other end, low freq started to slope around 30-35Hz... down
by less than 2db. but never did the sine wave naging baluktot.

and there's no way any imported OPT (less than $200) can do that.
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Re: Edrel's Irons

Postby fld » Wed Jan 04, 2012 7:12 am

Edrel's iron is good stuff!! sounds great & very durable. I agree with Brady- it competes and even betters the imported irons for a lot less $.
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Re: Edrel's Irons

Postby detubo » Wed Jan 04, 2012 8:09 am

D'best yan si edrel!! been using his irons for years.
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Re: Edrel's Irons

Postby Gaucho » Wed Jan 04, 2012 8:42 am

fld wrote:Edrel's iron is good stuff!! sounds great & very durable. I agree with Brady- it competes and even betters the imported irons for a lot less $.


+1......am using Edrel's power tranny for my amp
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Re: Edrel's Irons

Postby detubo » Wed Jan 04, 2012 10:16 am

Gaucho wrote:
fld wrote:Edrel's iron is good stuff!! sounds great & very durable. I agree with Brady- it competes and even betters the imported irons for a lot less $.


+1......am using Edrel's power tranny for my amp


gayagaya ka naman sa akin. idol mo ako noh!?
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Re: Edrel's Irons

Postby Gaucho » Wed Jan 04, 2012 10:52 am

detubo wrote:
Gaucho wrote:
fld wrote:Edrel's iron is good stuff!! sounds great & very durable. I agree with Brady- it competes and even betters the imported irons for a lot less $.


+1......am using Edrel's power tranny for my amp


gayagaya ka naman sa akin. idol mo ako noh!?


Yes idol!!! :rock: :rock: :rock: :rock:
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Re: Edrel's Irons

Postby edrel sison » Wed Jan 04, 2012 9:16 pm

these have been sent to Cebu today:
Image
Image

thanks brady.. :D :D
...for that never ending diy saga of yours and your friends..'appreciate your evaluation of my irons.

Tony thanks for always valuable info and our always never ending discussion :) :)

Thanks din Ferds for the compliment. Hope to visit you down there!

And what can I say, bosses Detubo and Gaucho. Thanks! Me utang pa akong irons kay Tonyboy! :D :D
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Re: Edrel's Irons

Postby setup1 » Wed Jan 04, 2012 10:35 pm

JEL projects using Edrel's iron:

Image
SE 10 monoblocks

Image
Detubo's not so simple 45 amp with over specified power transformers built by setup 2

Image
76/6SN7 preamp with remote volume control also built by setup2

Image
SE10 + SE2A3 mono integrated amps with variable phono EQ

Image
SE45 mono integrated amp for my study room system
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Re: Edrel's Irons

Postby brady » Thu Jan 05, 2012 7:02 am

Hi Edrel. Many thanks. Ang sa akin are just the filament x'former, and the pair of 45mA chokes (will try a parallel 182 to drive 2A3. 137v + and - at 20mA. It was Kit who set that operating point ... maybe Tony can chime in if he sees better point?)

The one clear advantage in ordering from Edrel is that he custom-winds. When one DIYs, secondaries of PS x'formers, choke L, I or even DCR, OPT or interstage Z, etc have to conform to one's design.
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Re: Edrel's Irons

Postby tony » Thu Jan 05, 2012 7:57 am

(will try a parallel 182 to drive 2A3. 137v + and - at 20mA. It was Kit who set that operating point ... maybe Tony can chime in if he sees better point?)


yes, 137volts at 20mA seems plenty, 137-50 volts is 87volts, about twice needed by the 2A3 grid, looking at your gain structure, the 182 has a mu of 5, the 2A3 has a mu of 4, so tube gains are about x20, your output traffo at 2.5k; to 8 ohms will have a turns ratio of 17, so your overall gain will be 20/17, about 1.17.....

so my concern about using this tube as driver is the very low gain....if you are looking at 3watt output into 8 ohms, you need to input 4.9/1.17 or about 4.8volts input......

IMHO, paralleling driver tubes won't help you, instead, you can use a step-up driver transformer with a ratio of 1:5 to get you more gain.....

this is 2A3 data:
Class A Amplifier
Plate Voltage ................................. 250 V
Grid No. 1 Voltage ............................ -45 V
Amplification Factor .......................... 4.2
Plate Resistance (approx) ..................... 800 Ω
Transconductance .............................. 5250 µ
Plate Current ................................. 60 mA
Load Resistance ............................... 2.5K Ω
Power Output (approx) ......................... 3.5 W
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Re: Edrel's Irons

Postby tony » Thu Jan 05, 2012 8:00 am

Tony thanks for always valuable info and our always never ending discussion


my pleasure, it's about time we have our own "Hammond" or "Edcor" transformer maker in the Philippines..... :clap: :clap: :clap:
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Re: Edrel's Irons

Postby edrel sison » Thu Jan 05, 2012 8:22 am

JE thanks so much for patronizing my irons. I still owe you that 45 sample OPT. :)

Thanks Tony & Brady..and may I mention Kit Aguilar of Ferd's Sounds & Images, thank you bay!
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Re: Edrel's Irons

Postby setup1 » Thu Jan 05, 2012 8:34 am

tony wrote:...it's about time we have our own "Hammond" or "Edcor" transformer maker in the Philippines..... :clap: :clap: :clap:


I've been using Hammond transformers since the mid 90s they are not bad for the price. But I have to emphasize, Edrel's power transformers are vastly superior in performance and build quality! Not to mention his unparalleled customer support. :rock:

Even after several hours of listening, Edrel's power transformers remain hardly lukewarm and most of the heat you will feel around the amp is caused by the glowing filaments from the tubes. AFAIK, he uses M6 lamination for his power transformers which is the minimum quality for use in output transformers and all the specified secondary winding voltages are spot on. :rock:
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Re: Edrel's Irons

Postby don » Thu Jan 05, 2012 10:42 am

CONGRATULATIONS EDREL ON YOUR "EDCOR" WORLD CLASS QUALITY TRANSFORMERS :rock: :rock: :rock:
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Re: Edrel's Irons

Postby tony » Thu Jan 05, 2012 11:24 am

AFAIK, he uses M6 lamination for his power transformers which is the minimum quality for use in output transformers and all the specified secondary winding voltages are spot on.


Edrel uses Z11 or RM18 cores for his traffo builds, the Z11 is the equivalent of M6, both are of the 0.35mmm thickness, in comparison, Deeco irons uses 0.5mm thick laminates, thus losses per pound of iron is lower with Edrel's traffos....

so material wise, Edrel uses the same laminate types as that of Hammonds......

the difference is is in the design of the coils......i remember getting an inquiry from a member here about power traffos that one can "fry an egg" on....i remember old day's irons were like that....

so judicious application of well know principles in traffo building makes for a cooler running traffo, a cooler running traffo will be quieter and will have lesser radiated feilds than ones that you can fry an egg on top of...... 8) :lol:
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Re: Edrel's Irons

Postby dudong » Thu Jan 05, 2012 11:46 am

tony wrote:
AFAIK, he uses M6 lamination for his power transformers which is the minimum quality for use in output transformers and all the specified secondary winding voltages are spot on.


Edrel uses Z11 or RM18 cores for his traffo builds, the Z11 is the equivalent of M6, both are of the 0.35mmm thickness, in comparison, Deeco irons uses 0.5mm thick laminates, thus losses per pound of iron is lower with Edrel's traffos....

so material wise, Edrel uses the same laminate types as that of Hammonds......

the difference is is in the design of the coils......i remember getting an inquiry from a member here about power traffos that one can "fry an egg" on....i remember old day's irons were like that....

so judicious application of well know principles in traffo building makes for a cooler running traffo, a cooler running traffo will be quieter and will have lesser radiated feilds than ones that you can fry an egg on top of...... 8) :lol:


Edrel rewound a busted power transformer from my Lafayette LA-310 (vintage 7189 amp), saying it now runs cooler is an understatement... it barely gets warm to the touch!

He also made one for my Sargent Rayment SR534 (vintage el84 amp) that was missing a power transformer; same results... barely gets warm.

and all the secondary voltages are spot on!

:clap: :clap: :clap:
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