(UPDATED-Solved) Trc-920 Not All About That Bass

UPDATE: So it's been a while since this, but things are finally better with this. I just ended up doing a speaker swap. The hard part for me was finding something affordable that would hopefully do the job well, and look clean. I ended up using some aftermarket car speakers with as low rms rating I could find (35w), with a pretty good sensitivity (92db). They also have a chrome whizzer cone, so the look more authentic than a two-way speaker. Here's the "after" compared to the "before" down lower. Let me know your opinions, harsh or not.

Edit: link fixed

https://youtu.be/lUDeTTdZ-aY


I'm not really sure what to do here. I have this 920 I fixed up for my buddy only to have him lose interest in it. So I bought it from him in the middle of fixing it. Got it pretty much restored, but I was testing it today and noticed the bass on it sucks... Makes it sound like blown speakers, but it plays mids/highs really nice.

I was under the impression it handles bass better than an M70, this is not my case. I took a video compared to my 931, which I know isn't fair, then a separate video of just my M70.

To be honest I'm not sure if am going to keep the box or not, as it was originally one my buddy had me get for him. But either way I want it working right, I've done so much to it already.

Let me know your thoughts.

920 vs. 931
http://youtu.be/5wYeDYpg33E

M70 alone
http://youtu.be/A3YT48X-A6Y

the 920 is known for blowing woofers or at least loosening them up till they fall apart. mine was the same way , i have gone through 2 sets of woofers so far and its all because of the power these put out . mine had a case of the rattles sometimes its just a loose dust cap. i think its a problem with the speakers not the radio.

Groovy... Did you use 920 speakers or find a suitable replacement? Both speakers on this do the same thing.

Interesting. I would think it's got some sort of issue either with the bass knob or a circuit in that part of the amp board that creates the bass.

Yes, these are known for having very strong bass, so if it doesn't you got a problem.

PM sent

A proper 920 will always have better bass than an M70 at low/mid volumes.

In fact, so will several other boxes, but I'd better shut up now.

Reli said:

A proper 920 will always have better bass than an M70 at low/mid volumes.

In fact, so will several other boxes, but I'd better shut up now.

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thats funny , reli
i agree

Lasonic TRC-920 said:

Interesting. I would think it's got some sort of issue either with the bass knob or a circuit in that part of the amp board that creates the bass.

Yes, these are known for having very strong bass, so if it doesn't you got a problem.

PM sent

Click to expand...

Hmm... I think I still have the spare parts boards I got from kraftmatic last year... I might have to look at them.

Clipping / distortion kills speakers. I doubt this model destroys speakers due to too much power!

It sounds like maybe a recap is in order.

i dont think my amp is clipping because after 25 + years of blaring loud music being played on this thing the speakers took a dump , the reason i say that is new speakers fixed the problem.

Hmm. So let's say it needs recapping. Is there a way to test/measure which are bad/out of spec? Or would I just replace everything?

And if its speakers... Well i dont have any 920 speakers at the moment, but could I put in some with the same ohm/wattage and be able to test okay? Or would the other properties of the speakers probably give me an inaccurate test?

I was kind of mentioning to Chris, I can us a multimeter and solder pretty good, but dont know hardly anything about checking caps/amps/diodes/etc... Im not afraid to try, but still learning, so a lot of it is so new to me.

trippy1313 said:

Hmm. So let's say it needs recapping. Is there a way to test/measure which are bad/out of spec? Or would I just replace everything?

And if its speakers... Well i dont have any 920 speakers at the moment, but could I put in some with the same ohm/wattage and be able to test okay? Or would the other properties of the speakers probably give me an inaccurate test?

I was kind of mentioning to Chris, I can us a multimeter and solder pretty good, but dont know hardly anything about checking caps/amps/diodes/etc... Im not afraid to try, but still learning, so a lot of it is so new to me.

Click to expand...

I guess we're going to learn together.

i would try some different woofers and see what happens , you should be ok with just about any 6 1/2 woofer for testing , i mean if you have the box apart just hook up a speaker to it , i can't remember if the woofers are 4 or 6 ohms but even most house speakers are 8 ohms so even that would work for testing . also if the tweeters sound normal then i don't think it could be the amp distorting . my trc 920 is more powerful than the 2 i owned before it and this thing will pound on some woofers . sometimes if somebody opened the box before they might have mixed up the wiring on the speakers , this was also the case on my 920 and it sounded very flat , once i got the damned wiring corrected it had so much bass the speakers went kablooey.

Alright cool. I should have a set of speakers in the garage somewhere. That sounds like the easiest thing to check first. Hopefully I can try to get to it in the next day or two. If that doesn't work I'll start looking for anything obviously bad/fried.I'll report back of course.

If you guys have any more ideas please post. I'll keep checking, and educating myself on caps and circuit board stuff.

JVC Floyd said:

i would try some different woofers and see what happens , you should be ok with just about any 6 1/2 woofer for testing , i mean if you have the box apart just hook up a speaker to it , i can't remember if the woofers are 4 or 6 ohms but even most house speakers are 8 ohms so even that would work for testing . also if the tweeters sound normal then i don't think it could be the amp distorting . my trc 920 is more powerful than the 2 i owned before it and this thing will pound on some woofers . sometimes if somebody opened the box before they might have mixed up the wiring on the speakers , this was also the case on my 920 and it sounded very flat , once i got the damned wiring corrected it had so much bass the speakers went kablooey.

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Yep, great place to start.

Well I found one speaker to test with. It seems to sound way better. I'm a little surprised because I cant see anything that looks wrong with it. Unless there's something with/under the dustcap? Isn't a blown speaker usually visible?

On another note. My dumb self destroyed my battery cover tonight. I'm not in a good mood about it. You'll see me in the "Wanted" section... Grrr.

A speaker with a overheated (damaged) voice coil will look perfect but sound bad.

If your multimeter is only a basic model, you will need a capacitance meter to test each individual cap (after you have desoldered it). I bought one from Ebay for $7 and it works well. I checked every cap on a M9994K and found most were stuffed. I then checked the meter by testing brand new caps and they read as slightly higher than spec.

Hopefully it's only your ancient Lasonic speakers at fault.

Back in the day, many Lasonic buyers were kids - try and tell kids to turn it down!!

jimmyjimmy19702010 said:

A speaker with a overheated (damaged) voice coil will look perfect but sound bad.
If your multimeter is only a basic model, you will need a capacitance meter to test each individual cap (after you have desoldered it). I bought one from Ebay for $7 and it works well. I checked every cap on a M9994K and found most were stuffed. I then checked the meter by testing brand new caps and they read as slightly higher than spec.
Hopefully it's only your ancient Lasonic speakers at fault.
Back in the day, many Lasonic buyers were kids - try and tell kids to turn it down!!

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Here's my multimeter... I wouldnt call it basic, but maybe just basic enough not to be able to huh?

You need one of these:
View attachment 13515

Updated at the top. 8/16/15