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stromberg carlson rp 721

churchill127

churchill127

Member
Hello All,

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First post! I have recently been bitten by the vintage electronics bug and after finishing a resto of a mid century SS Zenith I decided I wanted to try my hand at working with tubes. I was able to snag this stromberg off of craigslist from a nice gentleman liquidating his mother's estate. It was touching to hear the Christmas record that reminds him most of the unit playing on the changer (also relieving to hear that the unit works and tubes seem good). I am planning on a re-cap and check of all resistors, and would also like to modify the unit to be safe with a new cord.

I wanted to know the forum's opinion on whether I should try and save the cabinet, or try and make a little stand-alone SET amp out of this. The speakers do not look like any thing special, but are probably very efficient. Do you think that they would sound decent if placed in new, perhaps open backed, cabinets?

I do not believe this unit has the optional fm multiplexer, so I am not sure whether I want to save/restore the tuner; the fm dial is not turning past a certain point, looks like something is wrong with the dial cord or the posts it is wrapped around, not sure how annoying that is to fix/parts availability.

thanks everyone!
 
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I see pics! Your amp looks to be the ASR-110. I own its bigger brother the ASR-120. The only diff is the 110 uses two 7408's where the 120 uses four.

Member Tom Bavis will have some info for you! :thumbsup:

EDIT While I was typing, Gadget has Tom's link for you! :thumbsup:
 
Thanks for the info everyone. I am new to working on tube gear, and I wanted to make sure I am doing it safely. While powered off, there should be no problem with touching the amp chassis in order to remove it from the unit for repair, correct? I know that some of the capacitors can carry a charge for a while, but the chassis should not be hot as I understand it?

Also, anyone have any advice on whether putting the speakers in a new cabinet would sound decent? Anyone tried anything similar?
 
century tek said:
I see pics! Your amp looks to be the ASR-110. I own its bigger brother the ASR-120. The only diff is the 110 uses two 7408's where the 120 uses four.

Member Tom Bavis will have some info for you! :thumbsup:

EDIT While I was typing, Gadget has Tom's link for you! :thumbsup:
Click to expand...

did you pull it from the console? what do you use with it?
 
I would guess most of the charge on the filter caps would be gone after a few minutes, never the less, unplug, wait s half hour, and be careful pulling the chassis out, that your fingers dont accidentally find their way into the wiring. Once its out you can check to see if it has bled down properly by testing the terminals on the bottom of the aluminum can cap to chassis for DC voltage.

I would probably make an attempt to keep this as original as possible (keep the case and original speakers) with the possible exception of adding a switch so you could switch between the factory speakers, and some of your choosing.
 
Try changing the crossover cap on the speakers and see how that sounds first. You may also get benefits out of a proper 2 way crossover that keeps the large driver from running full range, and/or maybe adding a tweeter to extend the HF response. The drivers might be of decent quality, just not used as well as they could be. Maybe mix a sub in to fill out the bottom end, but I would put that outside the main cabinet. A sub with a turntable sitting directly above it is not a good combo. Probably why none of the consoles really went low in the first place.

There isn't a whole lot of power available here, so whatever you go with needs to be very efficient. Figure maybe 3 watts per channel from a single ended 6v6.
 
churchill127 said:
did you pull it from the console? what do you use with it?
Click to expand...

It was pulled from a console many years ago. The console is long gone but I still have the speakers and the tuner and passive preamplifier controls.

The amp is not an SC amp anymore :D It's more of a frankenamp with a bigger power transformer, 6L6GC tubes instead of the 7408's, bigger output transformers, and I re did the 7199 sockets to take the 6GH8/6U8 tubes. Basically the 6GH8 and 7199 are the same tube, just different pinout. I hear the 7199's are getting rare.:dunno:

I'm using it with a pair of very efficient Magnavox 15inch speakers. These are speakers that are out of one of their high end solid state consoles and not the one's from the earlier tube units.

In case you don't know, the 7408 is a 6V6GT equivalent.
 
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I think it's beautiful. The cabinet would look fantastic with just a little work. If it were me, and I had the room, I'd keep it original. Aside from a grounded cord and the upgrades @gadget73 recommended. Switchable external speaker out is a great idea.
 
Jazzbow said:
I think it's beautiful. The cabinet would look fantastic with just a little work. If it were me, and I had the room, I'd keep it original. Aside from a grounded cord and the upgrades @gadget73 recommended. Switchable external speaker out is a great idea.
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It really is! I love it. In your opinion, would you strip and refinish, or try and work with the existing finish as is? Also thank you, AK is a great community and I am excited to have a reason to post on it!
 
I might give it a rub-down with some Howard's Restore-A-Finish and see how it comes out. Looks to be in pretty good shape honestly.
 
century tek said:
It was pulled from a console many years ago. The console is long gone but I still have the speakers and the tuner and passive preamplifier controls.

The amp is not an SC amp anymore :D It's more of a frankenamp with a bigger power transformer, 6L6GC tubes instead of the 7408's, bigger output transformers, and I re did the 7199 sockets to take the 6GH8/6U8 tubes. Basically the 6GH8 and 7199 are the same tube, just different pinout. I hear the 7199's are getting rare.:dunno:

I'm using it with a pair of very efficient Magnavox 15inch speakers. These are speakers that are out of one of their high end solid state consoles and not the one's from the earlier tube units.

In case you don't know, the 7408 is a 6V6GT equivalent.
Click to expand...

Yea, I assumed that high efficiency speakers would really be necessary. Am I correct in the understanding that the 110 is a single ended triode amp?
 
Oh boy, so I just picked up a fisher philharmonic (https://www.radiomuseum.org/r/fisher_philharmonic_p_22_m_p_22.html), and I really can't keep both in cabinets... decisions decisions! Would anyone know whats the best way to go about finding other people who might be interested in one of these consoles in the St. Louis area?

gadget73 said:
I might give it a rub-down with some Howard's Restore-A-Finish and see how it comes out. Looks to be in pretty good shape honestly.
Click to expand...

I actually have some on hand so I will definitely give that a try!
 
churchill127 said:
Oh boy, so I just picked up a fisher philharmonic (https://www.radiomuseum.org/r/fisher_philharmonic_p_22_m_p_22.html), and I really can't keep both in cabinets... decisions decisions! Would anyone know whats the best way to go about finding other people who might be interested in one of these consoles in the St. Louis area?
Click to expand...

Is it this one?

http://www.fisherconsoles.com/

http://www.fisherconsoles.com/philharmonic II.html

Also just in case instead of having a single thread discussing to separate units maybe create a secondary thread for the Fisher if you have general questions about it. I would suggest you create thread in the dedicated Fisher forum

https://www.audiokarma.org/forums/index.php?forums/fisher.172/
 
Dswankey said:
Is it this one?

http://www.fisherconsoles.com/

http://www.fisherconsoles.com/philharmonic II.html

Also just in case instead of having a single thread discussing to separate units maybe create a secondary thread for the Fisher if you have general questions about it. I would suggest you create thread in the dedicated Fisher forum

https://www.audiokarma.org/forums/index.php?forums/fisher.172/
Click to expand...

Yes, it is the provincial/fruitwood version. Super heavy. I will make a new thread for it once I have it and can take some pictures of it.
 
churchill127 said:
It really is! I love it. In your opinion, would you strip and refinish, or try and work with the existing finish as is? Also thank you, AK is a great community and I am excited to have a reason to post on it!
Click to expand...

It's difficult to see exactly what condition the finish really is in. It doesn't look like it has a clear coat on it. If it doesn't you could just use a furniture touch-up marker on any nicks or scratches. At most I'd use a very fine sandpaper and lightly sand it.Maybe even just steel wool. From there it's really your choice. I personally like to use a wood revitalizer like Older English to bring it up. If it has a clear coat it depends on what condition it's in. You may want to strip the clear coat and redo it with a clear poly. The options are plentiful. Just depends on your taste. These are my Realistic speakers with just touch-up and lemon oil:
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I like this type of finish myself. I'm sure others will give you other options. It's really up to you.
 
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