Scott 340b cap replacement choices

analogaudioerc

analogaudioerc

New Member
Hello everyone,
I know this has been brought up before but I just wanted to get an an professional opinion on what is the best type of coupling cap to install in this receiver. Previous posts suggest that a polypropylene cap will retain stock sound dynamics, specifically the the Illinois brand/ type.
Just wondering if this still holds true or are there improvements in different brands such as OD that would be a better choice.
Thanks,
Chris
 
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Any polyester cap will work fine and sound good. Go to Digikey and search for the value and then narrow the search to polyester, then axial leaded cap, then voltage. Pick the cheapest one. A polypropylene cap is going to be larger. Digikey does have them.
 
analogaudioerc said:
Hello everyone,
I know this has been brought up before but I just wanted to get an an professional opinion on what is the best type of coupling cap to install in this receiver. Previous posts suggest that a polypropylene cap will retain stock sound dynamics, specifically the the Illinois brand/ type.
Just wondering if this still holds true or are there improvements in different brands such as OD that would be a better choice.
Thanks,
Chris
Click to expand...
A professional tech would just install the caps/brand that he has on hand. It would definitely NOT be a 'audiophile' type cap. If this is your rebuild then you can put in whatever you want. People use components based on various considerations sometimes it cost related , sometimes it is cost no object.
 
Thank-you both DR audio and primosounds for your input. That is what I was looking for. Just wasn't sure if it was polyester or polypropylene- seems like it's either or.

Cheers guys!
 
Solen and Illinois are good axial lead choices. Panasonic and Nichicon make a very good radial lead type,which can often be an easier fit in tight places.
Polypropylene is considered to be more ''audiophile grade'' than polyester,for whatever that's worth,but I believe the originals to be polyester.
 
IF you want a shortcut look here

http://audiokarma.org/forums/index.php?threads/hh-scott-340b-parts-list-rehab.745564/

and if you use my list any feedback would be greatly appreciated as this was supposed to be my resto project Christmas before last and that got derailed by Hayseed not getting my can caps done in time; real life, work, and GF's health issues have meant that the unit has been sitting in the back room ever since.

Edit: I cleaned out my dropbox and inadvertantly deleted the link to my spreadsheet. here it is

https://www.dropbox.com/s/7pa38zcvvy75cf2/Scott 340B Parts List.xlsx?dl=0
 
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I believe the originals were paper/wax. I don't think they were using polyester caps in 1964.
 
I used OD film and foil on my 340B. I would say the Scott sound has been retained. The originals were also a film and foil. You can cut them open and unwind the separate pieces. I found that in the 340B fitting larger caps was less of a challenge in the amp section than my 299C. The 340B has a deeper chassis. Removing the old caps in the preamp section was somewhat of a pain but the OD’s I used there were close to the size of the originals.
 
The 340B is a great receiver. I've used both Orange Drops (716 series polypro) and IC caps in my recent work and like them both very much. The IC's (yellow) tend to be a little smaller physically and, so, are often easier to place in a tight unit. I used OD's in my 340B and, like Destructor, found it had sufficient room to accommodate them. Sound was excellent. Good luck with your 340B.
 
Thanks for all the great replies. So I think it will be a toss up between the OD 716's or the IC caps. I like the IC's because they're fairly small and have axial leads.
Cheers Folks!
 
analogaudioerc said:
Thanks for all the great replies. So I think it will be a toss up between the OD 716's or the IC caps. I like the IC's because they're fairly small and have axial leads.
Cheers Folks!
Click to expand...
IIRC, Scott used "Ceracaps" for their coupling caps. I just installed orange drops in a Scott 222c rebuild and they sound pretty good.
 
dr*audio said:
I believe the originals were paper/wax. I don't think they were using polyester caps in 1964.
Click to expand...

Actually,they started using the polyester (Mylar) caps back in the 50's.Some brands (Sprague Difilm?) used dual-dielectrics,polyester & paper combined.

You are correct about the Scott using paper. The Ceracaps are just paper-dielectric capacitors housed in a ceramic tube.This type probably ranks right up there with the other ''worst caps in history'' mentioned in discussions. I'm not 100% certain,but I don't think I've ever found a good one:)
 
My Scott 340B had American Radionics, they had a paper case wrapped in a clear plastic film. My 299C had Ceracaps with the ceramic case. They may be from the same manufacturer. The construction of the innards are identical. Mylar or similar material and foil. I was able to easily unwind both. I have been using my 340B for the past two months or more Tough not in the same league as my Macs or some of my newer gear it is a fine sounding unit with a nice FM section. It’s one of my favorite pieces of gear, it performs well and is very nice looking, impressive with 19 tubes aglow.
 
Hey everyone, sorry to bring back a relatively old thread, and to hi-jack, but I didn't quite think this was worth a new thread.

I was wondering if anyone knew the details on the 4 large can caps on the 340b. I can see that one of them is (4) x 40MF, 300V, one is (4) x 20MF, 500V, but I cannot see the other two, as the transformer is in the way. Additionally, does anyone know for certain whether these are supposed to be micro or milli farad ratings? Typically micro is noted with a mu, but I have read that some of the older gear was marked simply with an "m". Obviously, this is quite a difference, so I need to be sure.

I am going to be replacing them, hopefully under the chassis, and would like to be sure before moving on.
 
The large can caps are all microfarad in value. The scott 340 has a large chassis so you could probably use individual caps that make up a single can. Or you can buy a multi section cap. I like the JJ multisection for price and performance. You also need to get a clamp as it is not a twist lock type. With the JJ you can also bump up the value a little of the first 2 sections in the power supply with the JJ 100 uf x 100uf x 500v because it uses SS rectifiers . Then use under the chassis caps. It maybe that you can get away with just changing this first can cap as it is the one which gets most of the work smoothing the AC. cheers, Primo
 
Here's the tread on my 340B restore with information on the can caps around post #7. It may be useful.
 
tdwpgtp said:
Hey everyone, sorry to bring back a relatively old thread, and to hi-jack, but I didn't quite think this was worth a new thread.

I was wondering if anyone knew the details on the 4 large can caps on the 340b. I can see that one of them is (4) x 40MF, 300V, one is (4) x 20MF, 500V, but I cannot see the other two, as the transformer is in the way. Additionally, does anyone know for certain whether these are supposed to be micro or milli farad ratings? Typically micro is noted with a mu, but I have read that some of the older gear was marked simply with an "m". Obviously, this is quite a difference, so I need to be sure.

I am going to be replacing them, hopefully under the chassis, and would like to be sure before moving on.
Click to expand...

Have a look here. I inadvertantly cleaned this out of my dropbox but I put it back up now, my apologies.

https://www.dropbox.com/s/7pa38zcvvy75cf2/Scott 340B Parts List.xlsx?dl=0

Edit: and there's also a link in the thread linked above to where you can download schematics and other factory documentation.
 
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primosounds said:
IIRC, Scott used "Ceracaps" for their coupling caps. I just installed orange drops in a Scott 222c rebuild and they sound pretty good.
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I have restored two 340B, a LK-72C, a 299D as well as a 299B.
All had the dreaded Ceracaps and in in each case I replaced them with Orange Drops.
This was when the current makers of multisection electrolytic can caps had not yet started churning out the modern production.
Due to lack of availability I tucked the Sprague Atom axial caps underdeck.
Tight fit!
Whatever you choose, be sure to replace the selenium bridge rectifier with a silicon and drop the voltage appropriately ( 220 ohm worked for me )
Also, you'll find that the carbon comp resistors have drifted and really should be replaced.
The choice of resistor type is a matter of debate, Metal film has worked well for me.
The ceramic "standee" resistors have also been known to be problematic too.....

Good luck and have fun!
 
podbaydoors said:
I have restored two 340B, a LK-72C, a 299D as well as a 299B.
All had the dreaded Ceracaps and in in each case I replaced them with Orange Drops.


Good luck and have fun!
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You should not denigrate the Ceracap name. They are actually a very high quality capacitor. Many in fact most of the ceracaps that i replaced still tested good. If you doubt that these caps are high quality just check what Jantsen charges for their ceramic bodied capacitors. While not the same construction as the Ceracap, comparing that ceramic bodied jantzen with the other caps in that line with different bodies will give you an idea of relative costs. I did a test where i left them in and listened to the amp for many hours. I thought the sound was rather soft and diffused. When i changed to the orange drops the sound tightened up so the original caps were probably a little leaky.
 
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