My humble Hitachi 9140E is finally delivering the goods!!

[BoomboxLover48]

There are blue caps, you can see them in this pic. Honestly the sound is mostly mids and mid-bass. Nothing deep, nothing very high. Also, this one was sold in Germany and it doesn't have a separate Loudness switch (the Loudness is supposedly integrated into the Volume circuit), so maybe that's part of the reason.

WP_20170109_13_29_27_Pro.jpg

I would at least remove the foam that's obstructing the bass ports . On a ported box if the vents are blocked even the slightest bit it will have a tremendous effect on the sound.if anything I would remove it all together and replace it with a small amount of poly fill.

Very correct!

Foam will interfere with the air movement.

Acoustic damping tiles or other materials can be used for sound absorption. Damping is done by making the internal surface not to reflect sound and absorb it.

 

[Reli]

I removed it, and the sound still sucks....no bass. So either my amps are dead, or the woofers are cheap garbage.

You want warm bass, you need a Telefunken. And BTW that box is sealed, not ported!

 

[Reli]

Still trying to find out what's wrong with this unit. Anyone know why the cap that goes to the tweeter would be grounded to the speaker frame? Never seen that before. Mistake?

 

[floyd]

Honestly I would bypass those caps and see what it sounds like, I'm not sure why it would be grounded to the speaker frame I would think that would short circuit and stop the sound all together.

 

[jimmyjimmy19702010]

Normal. Speaker baskets aren't electrically connected to the speaker terminals.

 

[Reli]

Normal. Speaker baskets aren't electrically connected to the speaker terminals.

Yours are wired the same?

 

[jimmyjimmy19702010]

Normal. Speaker baskets aren't electrically connected to the speaker terminals.

Yours are wired the same?

Yep

 

[caution]

Reli, I opened the back of one of my 9150W speakers to check the wiring.

Usually you have a terminal strip riveted to the woofer in dual speaker cabinets with a crossover cap for the tweeter, and it almost always has a third terminal that serves as a tie point for the output side of the cap, and the wire that feeds it to the tweeter.

But the speakers in these units don't have one so Hitachi used the woofer frame instead, which is isolated.

 

[Superduper]

Eric is right. On most boomboxes, the high pass capacitor leads are soldered onto a 3-terminal terminal-strip. But hitachi was too cheap to rivet one of those onto the speaker frame or cabinet so they just used the speaker frame for the 3rd mounting leg. The problem is that the speaker frame is a large target and splicing a connection there makes that a large "live" target. Any stray wire or ground could conceivably short out the amp, especially on a 1-pc box. Imagine doing live test and have something drop onto the speaker frame! Luckily, this is a 3-pc'er and is probably safe.

Now another observation is that it appears that there is a 1.5uf cap being used as a high pass cap. Wait.... what??? I hope that is an 8-ohm tweeter, otherwise if that is a 4-ohm (or less driver), it appears that it would crossover at 26.5khz. If 8-ohm tweeter, it is a far more reasonable 13khz +/-. However, an 8-ohm tweeter being mated with 3.2 ohm woofs means might could render the tweeter too subtle and overpowered by the woofers. Perhaps this is why Reli noticed not great highs?

 

[Reli]

Thanks guys! Mine do have a terminal riveted to the speaker as you can see in my pic, but it's just 2-terminal.

Yes it's an 8 ohm tweeter and a 1.5 cap. Specifically they are labeled Nicon 1.5MFD63WV

The channels are even, the switches are static-free, but there's no bass at all. So I'm guessing either they used different amps on mine, or they've gone bad. Eric do you know the amp code number, and is it 1 or 2 chips?

 

[jimmyjimmy19702010]

No bass at all? Hmmmm......... something isn't right for sure. The only 'issue' with these Hitachis is overly heavy bass and slightly subdued highs so you seem to have the opposite issue!?

 

[Reli]

Yeah it's mostly mids. Nothing deep at all. Trying to get any bass out of it requires cranking it up to where the mids become annoyingly loud.

The tweeters are OK, nothing special, but OK.

It's an AKA called the Sound 3030. Here's mine:
http://wikiboombox.com/Sound%203030

 

[caution]

Yeah it's two chips, TA7222P (see pics 9 and 10 here)

 

[Superduper]

Well probably the easiest way to see if it's a amp or speaker issue is to connect different speakers and also try those on another box, but that might be harder if this is one of those wireless speakers that connect when meshed with head unit. Also, might it be related to preamp circuit? Maybe increasing the value of the coupling caps in the audio signal path might allow it to pass more bass. Does yours look like new? On some audio equipment, worn caps do tend to mellow out and cause more muddy bass.

 

[Reli]

Yes the speakers are wireless, but they also have a cable in a hidden compartment.

Anyway, I connected them to another boombox and confirmed that these speakers still sound like junk. They go loud, but there's just not much bass. Maybe these Taiwanese woofers aren't as sensitive as the Japanese ones? Also, their surrounds are way too stiff. Whatever, it gives me an excuse to upgrade them. Time to search Ebay for some nice white or silver ones!