ROCKOLA AMP FIND!

[plexi50]

Does this look familiar Steve? Man i bet these OT's sound fantastic. Have not had a chance to do any checking out yet

[RicharD]

That is sweet.  Personall I think stereo guitar amps rule.  On top of that you got a beauty right there.  Color me jelous.

[plexi50]

It made my eyes pop open when i saw it. Some pots are dated 18th week of 1966. I want to but wont salvage the Pt & OT's. I better just put this away and restore it some day. Dont have a clue about the circuitry. Ya think Bill Haley and the comets was running through this at one time?

The tube compliment is: (1) 12AU7- (2) 12AT7- (2) 6CY7- (4) 7868 power tubes

[jjasilli]

Top 40 1966:  http://sentrydogalumni.us/top66.htm

1. The Ballad Of The Green Berets -- Sgt. Barry Sadler
2. Cherish -- Association
3. (You're My) Soul And Inspiration -- Righteous Brothers
4. Reach Out I'll Be There -- Four Tops
5. 96 Tears -- ? & The Mysterians
6. Last Train To Clarksville -- Monkees
7. Monday -- Monday -- Mama's & The Papa's
8. You Can't Hurry Love -- Supremes
9. Poor Side Of Town -- Johnny Rivers
10. California Dreamin' -- Mama's & The Papa's
11. Summer In The City -- Lovin' Spoonful
12. Born Free -- Roger Williams
13. These Boots Are Made For Walkin' -- Nancy Sinatra
14. What Becomes Of The Brokenhearted -- Jimmy Ruffin
15. Strangers In The Night -- Frank Sinatra
16. We Can Work It Out -- Beatles
17. Good Lovin' -- Young Rascals
18. Winchester Cathedral -- New Vaudeville Band
19. Hanky Panky -- Tommy James & The Shondells
20. When A Man Loves A Woman -- Percy Sledge
21. Paint It Black -- Rolling Stones
22. My Love -- Petula Clark
23. Lightin' Strikes -- Lou Christie
24. Wild Thing -- Troggs
25. Kicks -- Paul Revere & The Raiders
26. Sunshine Superman -- Donovan
27. Sunny -- Bobby Hebb
28. Paperback Writer -- Beatles
29. See You In September -- Happenings
30. You Keep Me Hangin' On -- Supremes
31. Lil' Red Riding Hood -- Sam The Sham & The Pharaohs
32. Devil With A Blue Dress On & Good Golly Miss Molly (Medley) -- Mitch Ryder & The Detroit Wheels
33. Good Vibrations -- Beach Boys
34. A Groovy Kind Of Love -- Mindbenders
35. You Don't Have To Say You Love Me -- Dusty Springfield
36. Born A Woman -- Sandy Posey
37. Cool Jerk -- The Capitols
38. Red Rubber Ball -- Cyrkle
39. B-A-B-Y -- Carla Thomas
40. Walk Away Renee -- Left Banke

[plexi50]

Now thats a good list of bands. The Green Beret's was an authoratative song. I think this puppy might just be a diamond in the rough. All the tubes test good. (2) of the 7868 power tubes are broken. So i would need (2) 7868 tubes. What do 7868 tubes sound like? Any other tube comparisons?

[rafe]

Fisher 400(stereo) used 7868 and sounds great ....There are a few guitar amps too....

[DummyLoad]

cool  find! re-cap it install a fresh set of output tubes and use it for what it was intended - HI-FI. can't tell me you don't have the need for some tuneage on the bench from time to time... ;)

--DL

[bibi]

Just curious,  I've seen these jukebox amps before and they often have the "output wattage" switches.
What is this exactly and how does it work?  Seems very handy for guitar amp...

Thanks!

[LooseChange]

Yeah man. Hook it up...
Two turntables and a microphone!

[kagliostro]

That is a VERY NICE find !

Kagliostro

[plexi50]

Anyone have any idea what the primary impedance these output transformers may be?

[plexi50]

I have been cleaning the inside guts up today. The more i look at the inside it really is an amazing solid built piece of beauty. I fired it up without the tubes and took voltage measurments. The PT fires up and i have a solid B+ of 394VDC on the power tube plates

I going to recap this as i have one axial cap that has spewed out its death goo. Whats death goo? First thing that came to mind

Very special OT's with several taps for different wattage output going to a rotary switch. I am looking forward to restoring this

If anyone has any tips or ideas please feel free to chime in. Im going to make it as brand new as possible











 

[TIMBO]

I've said in the past that you guys are so lucky that you are still able to find these gems. I'd be lucky to even find one thats TOASTED. I noticed that the circuit boards are mounted on their sides, i kinda like that idea but i'm sure it makes it a bit more difficult to work on.Great find

[DummyLoad]

Anyone have any idea what the primary impedance these output transformers may be?

6600ohms

http://tubedata.milbert.com/sheets/049/7/7868.pdf

[DummyLoad]

some food for thought....   

[plexi50]

Thanks TIMBO. It has taken me a few years to appreciate and leave certain finds like this as they are and restore them. In the past if i had found this all i would have seen is those transformers


Thanks DummyLoad. I got the RCA data yesterday and it said 6000 ohms but at the end of the line there was 10000. What does that mean? 
 

 

[DummyLoad]

...said 6000 ohms but at the end of the line there was 10000.

the last condition (10K load) is for a cathode bias AB1 - all other conditions presented are AB1 fixed bias.

[DummyLoad]

might be schema to your amp?

http://www.verntisdale.com/schem/431-32a.JPG
http://www.verntisdale.com/schem/431-32.JPG

--DL

[terminalgs]

So i would need (2) 7868 tubes. What do 7868 tubes sound like? Any other tube comparisons?

7868 is noval version of the octal 7591A. 

[plexi50]

might be schema to your amp?

http://www.verntisdale.com/schem/431-32a.JPG
http://www.verntisdale.com/schem/431-32.JPG

--DL

Ohhh! Awesome! Thanks much for finding that. Im going over it now

terminalgs  the 7591A has a great tone to it. Ordering can caps tommorrow and get this done while i have a break in work. This is going to be a new avenue for me. Imagine plexi50 not ripping apart an amp for it's parts. This will be only the second vintage Hi-Fi amp i will have restored. The Harman Kardon HK-20 Mono blocks were the first