I have just been given this:
It's a Hitachi TRK-3D8E boom box / guetto blaster / brixton breifcase.
Whatever you call it, it sounds pretty good. It's powered by either mains, or what looks to be 8 x Alkaline size D cells, which would make it 12V.
Being that it's full of retro charm, I would like to modernise it's capabilities a bit, whilst retaining the retro look and feel.
Initial ideas are:
There's an aux in on the back which I have been using with my phone and it works well.
Problems I have noticed:
I'm asking myself things like:
I welcome any and all suggestions on what to do with this and how to go about it!
It's a Hitachi TRK-3D8E boom box / guetto blaster / brixton breifcase.
Whatever you call it, it sounds pretty good. It's powered by either mains, or what looks to be 8 x Alkaline size D cells, which would make it 12V.
Being that it's full of retro charm, I would like to modernise it's capabilities a bit, whilst retaining the retro look and feel.
Initial ideas are:
- Different power source.. motorbike battery? Lithium cells?
- Add bluetooth connectivity (or similar)
- Add additional drivers - theres a LOT of space internally from what I can see though one of the vents
- TPA3118 chipsets run on 12V....
There's an aux in on the back which I have been using with my phone and it works well.
Problems I have noticed:
- There's a bit of hissing coming through - faulty equaliser sliders?
- Cosmetically, it needs work!
I'm asking myself things like:
- How much do I gut it?
- Do I preserve things like the equaliser?
- Could one of the tape decks make way for an OLED screen?
- Charging circuitry for the batteries? (there's a switch on the back to choose AC/DC so it's not designed to charge anything)
I welcome any and all suggestions on what to do with this and how to go about it!
If you want a rechargeable battery system.
Then use rechargeable D cell
Very simple solution no mods needed.
Having Bluetooth connectivity is a feasible mod.
Again no need to modify the electronics
There is Bluetooth cassette adaptors
Give it a nice clean up and your done
Then use rechargeable D cell
Very simple solution no mods needed.
Having Bluetooth connectivity is a feasible mod.
Again no need to modify the electronics
There is Bluetooth cassette adaptors
Give it a nice clean up and your done
Yes I suppose the ‘unadulterated’ option is there. A quick search says rechargeable high capacity D cells are about £20 for 4. Could use a small Bluetooth Adaptor hooked into the battery compartment and plugged into aux - add another £10 or so.
So for about £50 it’ll connect wirelessly and have rechargeable cells. It would be the least fun option though. 😛
I’m going to disassemble when I get a second today and see how much space we have in there to play with.
One of the reasons for wanting to mod is that is that the sound is very forward facing as is typical of the design. I’m hoping there’s enough room for a couple of small full rangers or similar facing out the vents at the side.
So for about £50 it’ll connect wirelessly and have rechargeable cells. It would be the least fun option though. 😛
I’m going to disassemble when I get a second today and see how much space we have in there to play with.
One of the reasons for wanting to mod is that is that the sound is very forward facing as is typical of the design. I’m hoping there’s enough room for a couple of small full rangers or similar facing out the vents at the side.
I’m gonna have fun with this….
It was made in 1986, plenty of Nintendo games made in 86. I know Zelda isn’t one of them but Mario decals will look cool. Original pixel artwork….
It was made in 1986, plenty of Nintendo games made in 86. I know Zelda isn’t one of them but Mario decals will look cool. Original pixel artwork….
That three slider "equaliser" is no more than a bass, mid and treble control set.
Very handy for balancing the sound of cassette tapes though!
Now, if only it were a Hitachi TRK-3D75E! 😎
Finally… the one I’ve had when I was 15: Hitachi 3D75E | The Walkman Archive
Finally… the one I’ve had when I was 15: Hitachi 3D75E | The Walkman Archive
I believe those are only suitable for car cassette players because of the way the bluetooth receiver has to hang out of the insertion slot - see image.
Attachments
Ok so I got it wrong, original Zelda was indeed 1986.
There’s definitely no need to use those cassette Bluetooth adaptors, there’s an aux in at the back:
It could probably be preserved with an RCA splitter or similar with switch mounted on the back. One side to the ports already there for aux in, the other side to one of these: Up2Stream Mini V3 WiFi And Bluetooth 5.0 Audio Receiver Board Module With Spotify Airplay DLNA 24bit 192kHz FLAC Multiroom|Wireless Adapter| - AliExpress
I already own one of these little boards and it makes my amplifier visible by Spotify and other music services. If you have more than one, you can synchronise playback between them. It runs on 5V. Would be pretty awesome added to the Hitachi… would give it WiFi, Bluetooth, Spotify Connect and more…
I’ve only had it a week, and don’t have a DAC connected to it at the moment so the sound is so so. I was trialing it before grabbing more of them and some DACs. You can use their DAC add on board but apparently you can do much better if you buy your own and solder to the correct pins.
I definitely think the EQ is dodgy. Not sure if it’s worth preserving it or replacing. Haven’t opened it up yet. Today has been busy.
The Mrs is already ordering acrylic paint and decals…. I think she may have seen some inspiration on Pinterest….
Who says we can’t make it into a TRK-3D75E? I’m fairly certain there’s a lot of space inside it. 3” drivers would probably fit nicely…..
There’s definitely no need to use those cassette Bluetooth adaptors, there’s an aux in at the back:
It could probably be preserved with an RCA splitter or similar with switch mounted on the back. One side to the ports already there for aux in, the other side to one of these: Up2Stream Mini V3 WiFi And Bluetooth 5.0 Audio Receiver Board Module With Spotify Airplay DLNA 24bit 192kHz FLAC Multiroom|Wireless Adapter| - AliExpress
I already own one of these little boards and it makes my amplifier visible by Spotify and other music services. If you have more than one, you can synchronise playback between them. It runs on 5V. Would be pretty awesome added to the Hitachi… would give it WiFi, Bluetooth, Spotify Connect and more…
I’ve only had it a week, and don’t have a DAC connected to it at the moment so the sound is so so. I was trialing it before grabbing more of them and some DACs. You can use their DAC add on board but apparently you can do much better if you buy your own and solder to the correct pins.
I definitely think the EQ is dodgy. Not sure if it’s worth preserving it or replacing. Haven’t opened it up yet. Today has been busy.
The Mrs is already ordering acrylic paint and decals…. I think she may have seen some inspiration on Pinterest….
Who says we can’t make it into a TRK-3D75E? I’m fairly certain there’s a lot of space inside it. 3” drivers would probably fit nicely…..
I opened this baby up today….. wow…. It’s busy
But there’s an absolute ton of space inside:
These end caps, a good space for extra drivers?
This guy obviously made his way in and couldn’t get out…..
I have located the 2 wires coming from the PSU that feed the 12V. Looks like the batteries feed into the PSU, then out again. Not sure why if it’s one or the other and no rechargeables.
So here comes a stupid question of mine…. Is it possible to add additional drivers by splicing into the existing wiring?
Is there any way of knowing if the left and right drivers are full range by looking at that circuit board? It’s difficult to see anything on the back of them to identify without complete disassembly.
But there’s an absolute ton of space inside:
These end caps, a good space for extra drivers?
This guy obviously made his way in and couldn’t get out…..
I have located the 2 wires coming from the PSU that feed the 12V. Looks like the batteries feed into the PSU, then out again. Not sure why if it’s one or the other and no rechargeables.
So here comes a stupid question of mine…. Is it possible to add additional drivers by splicing into the existing wiring?
Is there any way of knowing if the left and right drivers are full range by looking at that circuit board? It’s difficult to see anything on the back of them to identify without complete disassembly.
There are tweeters at the extreme left and right hand sides of the enclosure.
The full driver complement is as follows:
1 x 160 mm super woofer
2 x 120 mm midrange
2 x 20 mm tweeter.
I don't see the point of adding additional drivers inside the enclosure. In fact, doing so would be likely to affect the operation of the existing drivers.
The 8 ohm superwoofer is driven by a mono 8 W amplifier.
The 4 ohm mids are driven by a 2 x 3 W stereo amplifier.
The tweeters are 300 ohm and must piggy-back on the mids.
I wouldn't attempt to add additional drivers without full knowledge of the circuitry involved.
The total power rating is 14 W RMS @ 10% distortion - don't be fooled by the meaningless 60 W PMP (Peak Music Power) specification!
From where am I getting all this information? From the Service Manual of course! 😎
The 4 ohm mids are driven by a 2 x 3 W stereo amplifier.
The tweeters are 300 ohm and must piggy-back on the mids.
I wouldn't attempt to add additional drivers without full knowledge of the circuitry involved.
The total power rating is 14 W RMS @ 10% distortion - don't be fooled by the meaningless 60 W PMP (Peak Music Power) specification!
From where am I getting all this information? From the Service Manual of course! 😎
When the external supply is plugged in, the internal battery will be switched off - i.e. the power socket includes a switch which is operated by the 12 V power plug. There will be no recharging facility.
You would have to show me how the present drivers are loaded in the enclosure for me to answer that fully.
I presume the superwoofer is in its own sealed enclosure so that would be OK.
However, if the mids operate freely into the remainder of the enclosure, then mounting other drivers may subject them to unwanted back pressure.
Then, there's the consideration of impedance. Connecting additional drivers in parallel with the mids would lower the impedance, perhaps to the extent that the stereo amplifier would experience stress and distortion.
EDIT: In addition, there's the question of sensitivity. Adding drivers of greater sensitivity would result in most of the sound going to them and vice versa.
I presume the superwoofer is in its own sealed enclosure so that would be OK.
However, if the mids operate freely into the remainder of the enclosure, then mounting other drivers may subject them to unwanted back pressure.
Then, there's the consideration of impedance. Connecting additional drivers in parallel with the mids would lower the impedance, perhaps to the extent that the stereo amplifier would experience stress and distortion.
EDIT: In addition, there's the question of sensitivity. Adding drivers of greater sensitivity would result in most of the sound going to them and vice versa.
Last edited:
Oh and the 2 x 3 W stereo amplifier will be bandwidth limited to supply only midrange and high frequencies to the mids and tweeters.
I can see no advantage in augmenting this bandwidth with additional drivers - and the subwoofer, with its own dedicated amplifier, should need no augmentation.
I can see no advantage in augmenting this bandwidth with additional drivers - and the subwoofer, with its own dedicated amplifier, should need no augmentation.
Adverts!
That second photo of yours appears to show the woofer and mids operating into the same volume - correct?
That second photo of yours appears to show the woofer and mids operating into the same volume - correct?
No problem 🙂
So the bass is not enclosed:
And you’re right, the tweeter is chained off the mid:
Would it be a totally insane idea to locate on the PCB where the signal goes to the amplifiers and feed a separate TPA3118 to full rangers enclosed in PVC tube? Could add an additional switch to turn the TPA3118 on/off for “Classic Mode” and “Super Mega Awesome Improved 4D Mode” 😎
You may have guessed but I’m not quite ready to give up on the additional drivers 😛 I can feel this learning curve is going to have a ‘circuity’ feel to it. 😀
So the bass is not enclosed:
And you’re right, the tweeter is chained off the mid:
Would it be a totally insane idea to locate on the PCB where the signal goes to the amplifiers and feed a separate TPA3118 to full rangers enclosed in PVC tube? Could add an additional switch to turn the TPA3118 on/off for “Classic Mode” and “Super Mega Awesome Improved 4D Mode” 😎
You may have guessed but I’m not quite ready to give up on the additional drivers 😛 I can feel this learning curve is going to have a ‘circuity’ feel to it. 😀
Yes correct.
Edit:
Shame I’m not in touch with a guy I used to work with. He’d probably knock up a new PCB for a couple of bottles of Woods Rum!
Last edited: