BLASTING CAPS

[Jovie]

I suspect many people have boxes with compromised highs and don't realize it.Though I could sense something just wasn't right,I've been sitting on a number mediocre sounding boxes with no other solid points of reference.One such box is a Candle JTR-1287.Recently,I won its brother,a Samsung ST-875,and noticed a startling difference! The Samsung has wonderful and exceedingly sharp highs with its pots set to neutral.The Candle version had left me wondering if its tweeters were even real!

Then there was the Lasonic LPC-990 I found at a thrift shop a few years back.The box had disappointing highs as if its tweeters were mere props.Having found out about the filtering effects of tweeter capacitors,I decided to experiment with caps of a lower value to try getting more sound to the tweeters.Mistakenly buying them with a like value,I decided to replace them anyway to see what effect a change might have on the sound.One of my two friends having soldering equipment did the surgery.A veil was lifted and the highs from this box came to life!

Intrigued,I remembered my rather lack lustre Trident -cx473 I won on Ebay.This street box was sold through boutiques and by mail order back in the '80s.Expecting a street wise sonic assault,I was deeply disappointed with this box.If I turned the highs all the way up,I did notice a difference.Its highs began to sound like frying bacon.It sat in the corner rarely used for a year or two.Last night I had new caps of like values soldered into this box.....BOOM!!! The highs came to life in an ear splitting tour de force! After all it's the way any respectable classic street box should sound.This was accomplished with a total of $1.50 worth of Bipolar capacitors!

Judging from my experiments,speaker caps obviously go bad very frequently.Now I am wanting to refit my Prosonic 9962,Lasonic 920T,and the aforementioned Candle with brand new caps.The Prosonic has always served up bacon fry with its boom.The Lasonic either has bad caps or ones of the wrong values.This necessary maintenance is vastly overlooked by collectors.Most of us (myself include in many ways) just don't have the knowledge or courage necessary to crack open a box and tamper with things.However,having watched my friend solder in the new caps,I realize it to be a very simple and quick operation.All you need are the necessary tools.In many cases though its the only way to see what your blaster is really capable of doing.

 

[monchito]

jovie thats a good observation.. caps after all these years do dry out you would be surprized how well a box will sound when you replace those aging caps

 

[Superduper]

I've been a huge proponent of recapping our vintage boomboxes. The suggestion often gets brushed aside but the tweeter caps are just 2 amongst 120 of the caps in a boombox. If those are dried out, chances are, others are dried out too in the signal path. Imagine the improvement to the sound, performance, reliability, etc. if we systematically recap all our boomboxes. I'll bet 1/2 of the phantom maladies exprienced can be cured through an indiscriminate wholesale cap replacement campaign.

 

[oldskool69]

Norm, you are spot on. However, most members here are not technically savvy to get in there and desolder and remove and replace caps. I would not call it a major undertaking but will say that it can take some work. Especially on multi seperates component boxes.

 

[Superduper]

In the beginning, every box I got, I intended to go through 100%. Then I got caught up in collecting empty boxes -- boxes that look good but aren't 100% just to have 'em. The truth is, I couldn't get my money back out of them if I recapped them -- especially the lower end ones. I think lots of us are in that predicament, having many boomboxes that have glitches, gremlins and other issues that make them not 100% but nice to have, just to say we got one. I've slowed down now and hope to slowly rehabilitate them all, or at least until I get sick of them and unload them all. If you got 100 boomboxes, then I would say you are excused since you are clearly a collector and not a collector/user. Sure, you use boomboxes too. But I know there is no way in heck you are using all of them. There are going to be those that just sit on the shelves, or are stored away in some closet somewhere. However, for those of us who own 6 or 8 boomboxes -- nice ones -- I say go get them recapped. Every one that I've done, I've seen an improvement, whether it's in gremlin elimination or in sound improvement. If you can't do it, pay someone to do it. Once it's done, you'll feel better with just the knowledge that your boombox is healthy and will continue to be for years to come.

 

[bill]

i think some of the empty boxes might be better fodder for doing some kind of custom work instead of trying to breathe life into a box that never boomed in the first place.
now i have this old candle box it looks great and works great but sounds tepid.
i know damn straight it would sound better if someone redid the caps in it but.....
i just never would bother because it still would suck.

on the other hand i have a pretty cherry pc550 kicking in the bedroom . its almost perfect cosmetically but she needs a belt and i can hear that there is issues with the caps in that box.
i will most lkely chuck some cash at it.

then there is the boxes that i think are just fine for whatever reason they have not been used much or just kept in a nice enviroment or what ever but they are fine the way they are. i just cant see my fh-7 mk3 being improved with a recap its great as it is.
same as the sanyo c-7.

some tho i think for sure are worth doing.
it depends on what you are doing this collecting thing for.
the sound sure is one thing but a lot of people collect for the looks of the things.
some people arent that picky.
its hard to get really picky with the sound of a boombox for me but hey its all up to the user.

 

[Jovie]

bill-I've never claimed to have high standards for sound quality.My Candle sounds really good to me.Of course a Candle is a Candle,for what it is.I'm only meaning to say that the DIFFERENCE,mostly in dynamics,is big with new caps.It may sound like trash to some but it is,of course,still a boombox.

Though there are other caps in the boxes circuits,I would imagine the caps on the actual tweeters would make the biggest single difference in the highs.The process looks easy.With my 1 piece Candle,you remove perhaps 12 backplate screws.The front piece is the shallow one. Removing the back exposes the tweets without having to go through other things to reach them.You simply clip the old caps away,solder in the new,and your done.The whole process takes maybe 5 minutes for box disassembly,reassembly,and 5 minutes for the actual recapping,both tweets inclusive.As for speaker on 3 piece boxes,the procedure should always be this easy.Of course,a 1 piece box whose front piece is deep might mean the complication of removing components to reach the speakers.That's 10 minutes of work and 75 cents for each cap.

As for equipment,get a soldering pen and not a gun.Get one with interchangeable tips.Use acid free flux/solder.Perhaps there's Youtube tutorials,I'll have to check.Learning from a friend is always good.

 

[bill]

i was always a sucker at solder i am not sure anything could suck worse than me at soldering perhaps a solder sucker..

 

[hemiguy2006]

what is the best way to identify and obtain new caps for the job?

 

[Superduper]

A service manual will give you the entire parts list for all the components including capacitor values and tolerances. That way you can have the parts ready for the project before you begin. This is the ideal method. A service manual, if you can find it, is a very reasonably priced companion to the recapping, especially since it's a fairly large undertaking and in the grand scheme of the project, just a fractional part of the cost of the operation.

Otherwise, you can remove them 1 by 1. However, it's not always possible to see the values while they are on the board as the markings could be obstructed by an adjacent component. I stock nearly all commonly used values so this method works fine for me. Oh yeah, I always mark all the old electrolytic caps with a red sharpie before I begin. That way, I can see at a glance which ones are old and which are new as I work. Also, all the marks are oriented in the same direction (top, left/right/bottom, whatever). That way, if for some reason, the PCB is not marked and I forgot which pin is the negative/positive, I can always refer to the just removed cap and determine the polarity by the mark.

 

[monchito]

I've been a huge proponent of recapping our vintage boomboxes. The suggestion often gets brushed aside but the tweeter caps are just 2 amongst 120 of the caps in a boombox. If those are dried out, chances are, others are dried out too in the signal path. Imagine the improvement to the sound, performance, reliability, etc. if we systematically recap all our boomboxes. I'll bet 1/2 of the phantom maladies exprienced can be cured through an indiscriminate wholesale cap replacement campaign.

 

[eldorado]

not meaning to praise my Hitachi trk 8190 E,

but it has pure pure highs,

and hot enough to leave your ears ringing when you get home with it ( from the street ).

Damn.

Yes, it is important that a box has good definition, else its just a piece of electronics,

not a piece of art and engineering...

What a great audio it has... Very pure its like , sounds like a boombox should

and has a bit of a hollow sound to it, but in a good way.

Ok but i digress.

 

[monchito]

but even though it sounds good its always a good when you get a chance to change the caps,, i did a sanyo 920 which was in real bad shape and as soon as i changed the caps it sounded like new so with most boxes hitting the 20 to 30 year mark its always a good idea especially if you want to keep it humming for a very long time

 

[MONOLITHIC]

Intrigued,I remembered my rather lack lustre Trident -cx473 I won on Ebay.This street box was sold through boutiques and by mail order back in the '80s.Expecting a street wise sonic assault,I was deeply disappointed with this box.If I turned the highs all the way up,I did notice a difference.Its highs began to sound like frying bacon.It sat in the corner rarely used for a year or two.Last night I had new caps of like values soldered into this box.....BOOM!!! The highs came to life in an ear splitting tour de force! After all it's the way any respectable classic street box should sound.This was accomplished with a total of $1.50 worth of Bipolar capacitors!

Interesting to hear you say that, Jovie... My Trident and Prosonic sound EXACTLY like you said yours did. When it hits those "S" like sounds... Those tweeters are so bright, they hurt my ears after awhile! Right now, they're just sitting and I don't have any future plans to listen to 'em in the future.

 

[bill]

i dont know i think if your box has crud highs that are a sibilance enhancing experience you might as well chuck in some different tweeters if you are changing the caps.
i mean i think alot of cheaper made boomboxes would be improved just by swapping the speakers out.

 

[MONOLITHIC]

I'd like to add some top box Toshiba (S90/S93) tweeters to a Lasonic TRC-931.

That combo would give me the bass I want with the highs I enjoy.

 

[Jovie]

Just to clear things up Mono I speak of tweeters that put out little to nothing.This isn't anywhere near the output required to effect the "sibilance" that Bill speaks of.The only time I heard a change in the sound was by dialling the tweeters to max.Then i heard a faint sharpness to percussion.Its almost as if the frequency range handled bu the tweeters is diminished allowing less midrange through when caps get old.I surmise a bad cap rated 4.7 will sound like an 8 when its shot.I'm not addressing quality of sound but just raw output.I'm also not referring to overall volume but to the frequency range the cap allows the tweeter to reproduce.

I believe the brightness you speak are an abundance of mids from the tweeters at lower fidelity.This is a sound not heard from a boombox since the classic era.This is because everyone has rolled back their mids in subsequent years.With less mids to compete with,its easier to design a box with perceivably more bass.Admittedly an abundance of mids can be of higher fidelity (think classic Aiwa).These will not hurt your ears.You may think I'm "wakt" but sometimes I like my ears hurt

Some old boxes emphasize dynamics over fidelity.Many times,by both design or cost cutting,a lo-fi harshness to the highs was a part of this sound.Personally,I am fond of this admittedly lower fidelity type of sound.For me most any tweeter that puts out more is "better",even if there is some harshness involved.If you aren't listening to music live,sometimes a little extra emphasis will liven things up a bit.This I will admit.

 

[Superduper]

Just to clear things up Mono I speak of tweeters that put out little to nothing.This isn't anywhere near the output required to effect the "sibilance" that Bill speaks of.The only time I heard a change in the sound was by dialling the tweeters to max.Then i heard a faint sharpness to percussion.Its almost as if the frequency range handled bu the tweeters is diminished allowing less midrange through when caps get old.I surmise a bad cap rated 4.7 will sound like an 8 when its shot.I'm not addressing quality of sound but just raw output.I'm also not referring to overall volume but to the frequency range the cap allows the tweeter to reproduce.

I believe the brightness you speak are an abundance of mids from the tweeters at lower fidelity.This is a sound not heard from a boombox since the classic era.This is because everyone has rolled back their mids in subsequent years.With less mids to compete with,its easier to design a box with perceivably more bass.Admittedly an abundance of mids can be of higher fidelity (think classic Aiwa).These will not hurt your ears.You may think I'm "wakt" but sometimes I like my ears hurt

Some old boxes emphasize dynamics over fidelity.Many times,by both design or cost cutting,a lo-fi harshness to the highs was a part of this sound.Personally,I am fond of this admittedly lower fidelity type of sound.For me most any tweeter that puts out more is "better",even if there is some harshness involved.If you aren't listening to music live,sometimes a little extra emphasis will liven things up a bit.This I will admit.

Jovie. Your caps could possibly have shifted in value but it would be more likely that you're experiencing an increase in something known as ESR. ESR stands for Equivalent Series Resistance. An ideal capacitor would have pure capacitance and no ESR but in the real world, ESR is a reality. ESR is the AC resistance in the device. ESR failures of caps is only 1 form of failure. Of course the caps can also change in value (which is less critical since most have tolerances from -20% to +50% anyway. Finally, caps can also faile open or shorted. Just saying that a change in value is only one aspect of capacitor failure.

 

[Line Out]

So, I'm thinking of recapping some of my boomers. Should I just go ahead and replace all or is there some caps that will matter more than others?