Topic: RCA-Victor stereo / GE reciever

[efren_]

Just got these antique tube recievers from junk, the rca-victor is a SE with 6AR5 output and 12AV6 driver, 100VAC, double A.M tuner. when i test it Umusok despite the fact that I have 100V xformer(find out later it was caused by leaky PSU filter caps,) it fried the 6CA4 rectifier tube :'( so I temporarily replaced it with SS diodes, the filter caps originaly is 20mfd, replaced it w/ 150mfd., further test showed that all capacitors(electrolytic specially), were way out of tolerance, i fired it up once again anyway, I was surprised as it was dead silent while idling, tested some Stan getz/Joao Gilberto cd's, if the JLH class A gave me goose bumps, these piece of junk raised all  the hairs in my  bodies ,its been 25 years since i last heard a tube amp sing; despite the fact it is only 5W/ch, very transparent from mid to high driving my Altech Lansing sattelites, its more than enough in a 20X20m room.another thing, I tapped the output from 12AV6 driver via 270k resistor to isolate the high impedance of the  tube amp and feed it to the low Z of  JLH amp, wow even the SS amp sounded like tube amp! the only diffrence is the SS amp has got the punch,(JLH is 12W/Ch). Right now  i stripped the whole RCA-Victor down to the last wire and tube socket, rebuild it as amp only minus the bulky AM double tuner. how about the GE reciever? Have to set it aside for a while,..so it is posible for SS amp to sound "tubey" by feeding it with a signal from a tube driver. Sir JOJO D. might have a more detailed explanation.

[JojoD818]

Wow congrats Efren! And Merry Christmas na din! 

Sayang naman yun rectifier tube, at least next time try to check the caps first before firing it up. Aging caps needs to be slowly "awakened" to prevent any magic smoke... 

By using your JLH amp with the tubes up front, you now have a very nice hybrid setup. 

Where did you connected the 270K again?

[efren_]

the 270 k res sir jojo is connected in the control grid of 6AR5. luckily the GE reciever has 5Y3 rect that i can use, only i have to do a little metal work to fit the larger tube. the GE have also 6F6gt, since im planning to replace the innards with a transistorized AM kit and just preserve the external cabinet and knobs for antiquity's sake, those 6F6 should be exellent for a SE amp, driven by C3G in triode mode( I learned from you, hat's off to you sir!)

[efren_]

BTW sir JOJO, are they still selling output transformer at raon, particularly LION brand? or  perhaps some better OT that can be matched with 6F6GT,?

[JojoD818]

I believe wala na ngayon yun "universal" opt na LION brand pero you can try looking dun sa shop sa tapat ng Akihabara, madami ako nasilip na LION transformers doon and Andrew name nun owner. Nasa tabi siya ng dental supplies store. 

Pero da best is PM mo si ka edrel sison! Sigurado ka pa sa quality ng opts niya sir efren. 

[efren_]

many thanx sir jojo for the info, i will be sharing pix of the project when finnished. Happy New Year to you and to all tube enthusiast!!!

[edrel sison]

thanks for mentioning jojo..

efren if i were you i will try to restore the amp back to its original state where possible.

most modern amps, even tubed for that matter cannot even come close to the sound quality of vintage amps..

if the OPTs are original we can restore it to its original specs. i have had my share of restoring OPTs of dynaco MKIII, ST70s, pioneer and sansui too.

[JojoD818]

@edrel, no problem. good news yan restoration ng vintage tranny...

@efren, if edrel accepts tranny restoration then that would be the most viable move or pagawa ka sa kanya ng bago outputs...

[ATJr.]

efren, is that single ended? whatever you do, do not lose those output irons.....

and play it safe, tube amps have higher voltages than ss amps...

EDREL,

eto na yung output trffos gamit yung z11 cores mo...

[efren_]

Sirs,
i already stripped the RCA chassis, restoring it to its original state is imposible i think. original wooden cabinet desintegrated upon lifting due to age and termites, further research on the net it was model B-501 circa 1954. even the power transformer fish paper was not spared by termites, it must be the wax coating that they find so delectable . the output transformer were spared, primary resistance on my FLUKE 177 DMM reads 497ohms & 503 ohms on the other, secondaries have both around 9.4ohms. when its up and running, i'll PM sir edrel when i begin the 6F6 SE project for the output xformers. the GE radio is more worth restoring, the cabinet & knobs is still intact. the "magic eye" however was broken when it dangle and got pinched by the cabinet . i will upload pix via photobucket while they were still untouched by my tweaky itchy hands

[edrel sison]

nice one tony! i should have brought you 2 sets of imported endbells..

[macdon]

nice one tony! i should have brought you 2 sets of imported endbells..

OP sorry for the OT:

Edrel - do you have tranny covers as well?

[ATJr.]

nice one tony! i should have brought you 2 sets of imported endbells..

edrel, do you have endbells that mount upright? the ones from golden mars are not so good...

[ATJr.]

efren, those magic eye tubes may still be available, if you have the part number we can look for it...

[efren_]

Sir Tony,
yes sir, single ended, and im handling it like an egg.the size is like a 750mA transformer. Chassis is hot(one of AC line is connected directly), it gave me a shocker countless times, i learned my lesson when i accidentaly touched B+350v line while my other hand is on the concrete floor, it nearly knock the daylights out of me, and i can actually hear myself scream :othat when i decided to use isolation transformer,,whew!!!

[ATJr.]

Sir Tony,
yes sir, single ended, and im handling it like an egg.the size is like a 750mA transformer. Chassis is hot(one of AC line is connected directly), it gave me a shocker countless times, i learned my lesson when i accidentaly touched B+350v line while my other hand is on the concrete floor, it nearly knock the daylights out of me, and i can actually hear myself scream :othat when i decided to use isolation transformer,,whew!!!

that's scary, one reason i shifted to ss long time ago is this fear of shocks....
i suggest that you get an isolation transformer like the one shown below...


the traffo is made from EI 1 3/4 x 3 inch stack, 320 turns of ga16 for both primary and secondary coils....
also a rubber mat will protect you from shocks....

[efren_]

sir Tony,
a rubber mat...i never thought of that. Thanx sir Tony, i will implement this in my workplace. now for the pix...<a href="http://s646.photobucket.com/albums/uu184/efrennoble/?action=view&current=Image010.jpg" target="_blank"><img src="http://i646.photobucket.com/albums/uu184/efrennoble/Image010.jpg" border="0" alt="GE"></a>

<a href="http://s646.photobucket.com/albums/uu184/efrennoble/?action=view&current=Image017.jpg" target="_blank"><img src="http://i646.photobucket.com/albums/uu184/efrennoble/Image017.jpg" border="0" alt="GE reciever"></a>

[JojoD818]

Nice one Tony, kung may halimaw na sub yan na malamang ang halimaw na isolation tranny! 

[edrel sison]

OP sorry for the OT:

Edrel - do you have tranny covers as well?

hi mr. macdon how are you?

tranny cover is i think also the same as endbell. yes i have those..

[edrel sison]

EDREL,

eto na yung output trffos gamit yung z11 cores mo...

hi tony by the way why have you replaced the original irons? i saw them and i think they were good..

and you have a nice camera shots right there. what cam is that?

[ATJr.]

hi tony by the way why have you replaced the original irons? i saw them and i think they were good..

and you have a nice camera shots right there. what cam is that?

hi edrel, actually i have another set of coils made, i plan to test/compare your irons with that of rey luis's....i used an nokia n73 camera...

[edrel sison]

tony that one is better, i believe they were from US surplus and are grain oriented. i have compared an original dynaco cores with my Z11 using the same bobbin OPT winding and the original sounded better to me.

the advantage of using new ones is that you dont have much air gaps as compared to using surplus. for power transformers though, new cores are best.

if only i can get some grain oriented steel in new condition...and at 200 kgs or so..

[ATJr.]

edrel,
i got this spreadsheet from bud purvine, and z11 should be the same as m6, i wanted to confirm but unfortunately my Heatkit IG-18 is still in the province....

[efren_]

Sirs,
i did not mention in my previous post that there is a turn table included in the RCA-Victor tube amp, i dont know if this mechanical piece of contraption worth restoring but in case somebody is interested, its up for grabs FOC, just let me know....

[edrel sison]

efren what tt is that? kung garrard yan please reserve! seriously let us know what table you found out there..

[efren_]

Sir Edrel,
unfortunately sir the turnT is Victor etched on top where you place the vynil. Also there's an inscription "his masters voice" a dog facing a pre-war turnT; I only recall seeing that in the movie Saving Private Ryan; there's a volume control, and below it two single pot ganged mechanically by a dial cord, a squirrel cage type of motor(100Volts) with a mechanical speed control 16, 33, 45....the switch below the arm is broken though i think repairable. the pick-up is magnetic, the needle is nowhere to be found on four corners are the mounting studs for springs; two springs are missing.

[edrel sison]

thanks efren. if you are able to take pics and post it here surely will generate some interests. why not repair it and use for the meantime .ill send you some LPs for testing if you want..

[alexg]

hi edrel, actually i have another set of coils made, i plan to test/compare your irons with that of rey luis's....i used an nokia n73 camera...

Is Rey Luis' the winder from Tondo?

I think I talked to him one time.

[ATJr.]

Is Rey Luis' the winder from Tondo?

I think I talked to him one time.

he is from malabon or caloocan, you can reach him thru 352-5420, afaik, he makes traffos for rene rivo...

[efren_]

from this
to this

the nostalgic glow