Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Jul Thu 02, 2020 11:55 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 30 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: Adding Bass to Antique Radios
PostPosted: Aug Thu 11, 2011 6:30 am 
Member
User avatar

Joined: Sep Sat 11, 2010 5:36 am
Posts: 590
I have a radio I'd like to reduce treble and add bass to. I read something about changing the size of a certain capacitor. Could someone please lead me in the right direction? Thanks!
http://www.nostalgiaair.org/PagesByMode ... 005982.pdf

_________________
Mike


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Thu 11, 2011 6:44 am 
Member
User avatar

Joined: Jan Sun 24, 2010 7:59 am
Posts: 5957
Location: Pro Tech, Philadelphia Pa.
Remove capacitor "16", the 240mmf.
Replace it with a .005uf in SERIES with a 47K resistor.

_________________
"Accept the fact that some days you are the pigeon, and some days you are the statue."


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Thu 11, 2011 7:08 am 
Member
User avatar

Joined: Sep Sat 11, 2010 5:36 am
Posts: 590
Thanks a lot. That schematic is hard to read. I believe it is #18 cap. So I will remove one cap and replace with a cap & resistor connected together, right? Thanks!!!

_________________
Mike


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Thu 11, 2011 1:30 pm 
Member

Joined: May Sat 22, 2010 4:42 pm
Posts: 2987
There's no easy way to "add bass" to an AA5. You can kill highs as someone suggested by putting a capacitor-resistor pair across the signal path, but that's not terribly satisfying-- it just gives a gentle attenuation slope which just makes things muddier sounding, not so much "mellow".

You also have the problem that there is not that much power available for extra bass, and the speaker just isn't capable of handling or efficiently reproducing much bass anyway.

Perhaps the most fruitful way to get more bass would be to go to a larger speaker, or put an enclosure behind the speaker, perhaps with a bass port-- of course often not possible in a small cabinet.


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Thu 11, 2011 2:44 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 4991
Location: Gainesville, Florida
try different values of plate capacitor #15 .01mF output tube 35L6. changes tone


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Thu 11, 2011 4:01 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 14264
Location: S. Dartmouth MA 02748-1225 USA
As a follow-up, note that this radio uses a speaker with a hum-bucking coil, it is evident the designers expected a certain amount of hum to be present in the audio
YMMV

Chas

_________________
List' & I will Enchant Thine Ear


Last edited by Chas on Apr Thu 09, 2020 5:03 pm, edited 3 times in total.

Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Thu 11, 2011 4:03 pm 
Member

Joined: Oct Sat 20, 2007 3:36 am
Posts: 11481
Location: Southern NH, 03076
A larger output transformer would be the first step as the cheapo originals do not have enough iron to support the bass no matter what you tried to do first.

Then tweak values and maybe a modern wider range speaker; auto radios are a good source.

Carl


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Thu 11, 2011 5:59 pm 
Member
User avatar

Joined: Jan Sun 24, 2010 7:59 am
Posts: 5957
Location: Pro Tech, Philadelphia Pa.
Chas wrote:
Do not remove #18 cap., this is the "tweet" filter that reduces the whistle of adjacent station carriers. Increasing the value, say to 470pf will reduce the high frequency response with no enhancement of the bass.


Indeed, leaving the 270mmf in place won't hurt.
My earlier suggestion was just a simple fix to "contour" the audio to be less irritating and enhance the bass, allowing some treble to get through, resulting in a much richer sound.

There are several ways to gain enhancement in radios, depending on the set.

_________________
"Accept the fact that some days you are the pigeon, and some days you are the statue."


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Thu 11, 2011 6:17 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 4991
Location: Gainesville, Florida
I have used 25mF bypass cathode of output tube with best results in a very similar GE using same tube line-up


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Thu 11, 2011 11:55 pm 
Member
User avatar

Joined: Jun Wed 08, 2011 2:33 am
Posts: 10544
Location: Ohio 45177
I would be concerned that in alot of old radios, more bass brings more hum. If they have a PM type speaker, a modern replacement with a looser suspension, like foam or rubber, and a lower resonance might help what bass is there. Small stiff speakers do not do too well in that respect, but as others have stated, with the smallish output transformers and lower value coupling and cathode bypass caps, that new speaker might not help as much as hoped. Might be the last step. Maybe you could warm up the sound some but not achieve anything like rattling bass output. Then the cabinet size and construction is a limit, too. I would maybe lift one end of that .01 uF that is across the output transformer, temporarily, to see how it affects the treble, though. Might select a different smaller value or leave it out, if it improves it in your case. Or leave it in and put a pot in series to vary it. Inside, in a set and forget configuration. It might sound better with the cap in there. Things like a narrow IF bandpass might affect treble on local stations, too. Get yourself a big German tube set if you want AM with lots of bass and treble, and controls!

_________________
Reddy Kilowatt says; You smell smoke? Sorry about that!


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Fri 12, 2011 12:29 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 4991
Location: Gainesville, Florida
true. telefunken sound incredible. AM quiet like FM


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Fri 12, 2011 3:11 am 
Member
User avatar

Joined: Sep Thu 28, 2006 12:51 pm
Posts: 6953
Location: Sarasota, Florida
When I was growing up I recall trying to add bass to a radio by using bigger capacitors, etc. Never got much.

The fact of the matter is, adding bass makes the radio sound richer in most cases, and if it was easy to do so -- using a .01 instead of a .001 for example, it would already have been done at the factory. Bass can be added by changing the audio transformers, changing the speaker, redesigning the enclosure, redesigning the tone circuitry, and other similar things -- and this is done in the form of bigger, more expensive radios.

I also remember reading in a book somewhere -- an older book o fthe 50's -- that the sound coming from a radio or other device has a more pleasant sound if the highs and lows are rounded off the same amount -- in other words AM radio with attenuated highs sounds more pleasant if the bass is rolled off as well. I disagree, but who am I?

_________________
Gary Tayman, Sarasota, Florida


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Fri 12, 2011 4:08 am 
Member
User avatar

Joined: Sep Sat 11, 2010 5:36 am
Posts: 590
Many radios have a switch where you can switch from more tone to more bass. It seems like this is just one capacitor being grounded to chassis or disconnected. Am I right?

A lot of good ideas here. Probably the best idea will depend on one's particular radio. As far as the hum is concerned, I have that under good control as long as I don't swap out of 35L6 with a 50L6 to compensate for 122 volt house current. A 50L6 created noticeable hum.

Thanks!!!

_________________
Mike


Last edited by mcoates on Aug Fri 12, 2011 8:28 am, edited 2 times in total.

Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Fri 12, 2011 4:36 am 
Member

Joined: Oct Wed 14, 2009 6:36 am
Posts: 5835
Location: New York USA
Mike, If your 50L6 created hum, it is probably defective, heater to cathode leakage. Try another 50L6.
Don


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Fri 12, 2011 10:41 am 
Member
User avatar

Joined: Sep Thu 28, 2006 12:51 pm
Posts: 6953
Location: Sarasota, Florida
Quote:
Many radios have a switch where you can switch from more tone to more bass. It seems like this is just one capacitor being grounded to chassis or disconnected. Am I right?


A tone control of this type does not boost bass; it reduces treble.

This simple method came with the introduction of electric record players. Records have pre-emphasis, in other words the highs are boosted. When you play it back, the highs are cut by the same amount, so response will be flat, but background noise will be reduced. The only problem with this, record companies did not agree on how much pre-emphasis to use. Victor used one standard, Mercury used another, Decca used yet another, Capitol still another, and so on. On many record players, a capacitor was shunted to ground for the purpose of de-emphasis. It was done through a pot, so you could adjust the amount of de-emphasis depending on the record being played. THAT was the original tone control. Obviously consumers didn't adjust this by any scientific standard, rather they adjusted it for the most pleasing tone. The control got popular, and found its way into radios and other devices. BTW, for LP's and 45's there is an RIAA standard for pre-emphasis; for the older 78's there was no standard.

Better radios, and more modern stereos, used a feedback array of resistors and capacitors that could actually boost or cut highs and lows. These had a treble and a bass control.

Can you install such an array into an AA5 radio? Probably, but remember the audio transformer, the speaker, the cabinet, are not conducive to giving you much bass anyway, and you'll be disappointed with the results. As I said earlier, the easiest way to get more bass is to purchase a more expensive radio.

_________________
Gary Tayman, Sarasota, Florida


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Fri 12, 2011 2:19 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 4991
Location: Gainesville, Florida
wow we should have write a book section. high frequency filter :shock:


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Fri 12, 2011 4:21 pm 
Member
User avatar

Joined: Sep Thu 28, 2006 12:51 pm
Posts: 6953
Location: Sarasota, Florida
tubeAMP wrote:
wow we should have write a book section. high frequency filter :shock:



There are already plenty of books out there, and you can read in detail how it's all done.

But the point I'm trying to make is the fact that a lot of components work together to provide sound quality that's better than your typical AA5 table set. A big speaker in its own enclosure will probably make the biggest difference, but there is no substitute for obtaining another radio with all of this additional hardware designed into it. Changing one or two caps to add bass is akin to saying you want your Toyota Camry to perform like a Ferrari by using different spark plugs. If you want an antique radio to perform better, there are some good-performing antiques out there. You like bass? Get an RCA or Zenith console.

Any of these other ideas, changing caps, using a different speaker, even trying to fit a bigger transformer, might change the bass a little, but not enough difference to be worth the trouble.

_________________
Gary Tayman, Sarasota, Florida


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Fri 12, 2011 5:46 pm 
Member
User avatar

Joined: Sep Sat 11, 2010 5:36 am
Posts: 590
Thanks for your detailed explanations. No need to buy another set for the purposes of this thread. I have a Zenith 11s474 and a General Electric E-62 which are my favorites for a nice tone. The change that I wanted to make to the Farnsworth was just a tweak, preserving the original sound as much as possible. I'm not too keen on modified sets. I do have a hearing problem where shrill sounds are very uncomfortable. Great tips for anyone who stumbles upon this thread. I'm certainly going to try a few for my own education and satisfaction. Thanks soooo much!!!

_________________
Mike


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Fri 12, 2011 7:13 pm 
Member

Joined: Oct Sun 01, 2006 10:09 pm
Posts: 600
Location: FORT WORTH
I have a Zenith 10S153 that I restored. The sound was less than remarkable and I was more interested in good sound than authenticity. First, I replaced the speaker with a 15" high compliance speaker, retaining the field coil from the old speaker for the power supply. It was better, but no cigar. Then I replaced the output transformer with a modern, heavy, push-pull transformer to take advantage of the two 6L6s. It was better yet, but the treble was muddy. I added a Klipsch mid-range horn and crossover. Stunning! Everyone who hears it thinks it is FM. I spend many enjoyable evenings in front of it listening to KAAM.

OK. So, I spent more money on the mods than the radio was worth. It brings me much satisfaction. Put a price tag on that!

Let the outrage begin.

Dr Bill


Top
 Profile  
 
 Post subject: Re: Adding Bass to Antique Radios
PostPosted: Aug Fri 12, 2011 7:36 pm 
Moderator
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 12600
Location: Berkeley, CA 94709
drbill wrote:
I have a Zenith 10S153 that I restored. The sound was less than remarkable and I was more interested in good sound than authenticity. First, I replaced the speaker with a 15" high compliance speaker, retaining the field coil from the old speaker for the power supply. It was better, but no cigar. Then I replaced the output transformer with a modern, heavy, push-pull transformer to take advantage of the two 6L6s. It was better yet, but the treble was muddy. I added a Klipsch mid-range horn and crossover. Stunning! Everyone who hears it thinks it is FM. I spend many enjoyable evenings in front of it listening to KAAM.

OK. So, I spent more money on the mods than the radio was worth. It brings me much satisfaction. Put a price tag on that!

Let the outrage begin.

Dr Bill


I'm outraged! :lol: Seriously though, that kind of stuff is fun to do once in awhile. I wouldn't do it to a gem like a 12A58 Baby Stratosphere, but the 10S153 is a fairly common radio -- and heck, if someone was dying to do so, they could always bring it back to what it was pretty easily.

I have a huge 14-tube Detrola 192E console that uses four 42 audio output tubes, though they're not running anywhere near their full capability. The stock 12-inch speaker on mine wasn't in the greatest shape, though it was working. It's mounted on a 15-12 inch reducing ring, so it was simple to swap in an early 1940's 15-inch Magnavox field coil speaker. I also put in an extra filter cap and choke since the FC resistance on the Maggy speaker was lower than the original. This made a noticeable improvement in the overall sound quality, though higher end was kind of muddy. I added a coaxial tweeter mounted on four arms and played around with some caps to create a crossover and now it sounds great, and I've still never come close to turning it up all the way.

It's remarkable how few consumer radios from the 1930's have an actual bass amplifier and boost circuit rather than just a treble cut. Of all the radios I own, the only one to have it is my Philco 38-690. The bass on that thing leaves the other radios in the dust.

Bob


Top
 Profile  
 
Post New Topic Post Reply  [ 30 posts ]  Moderators: Marcc, Norm Leal Go to page 1, 2  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: hockingcountyhillbilly, jdivito, jrscpu2004 and 33 guests



Search for:
Jump to:  


































-->


Privacy Policy :: Powered by phpBB