Bass tube question for anyone who remembers them!

[Rich]

So after creating this thread, my brother scored this locally for less than a filling amount of McDonald's Big Macs. Proper nostalgia and ideal for his 90's car.





What I would like to know is if anyone has had any past experience of installing one of these. I have no info with it and finding anything is proving obviously impossible being this some Argos special. The power side is fine, got that down, but the speaker connections have me a smidge baffled.





I have 'R Signal in +' and 'R L Signal in -'. Would you say that the wiring piggybacks off of one speaker channel or both, the + of one and the - of the opposite side, to create some kind of balance in sound? Any help gratefully received, as you can see the nephew is wanting to get it installed in his dad's car!

[strikey]

I might...possibly....still have the instructions for my old one stashed in a drawer in the garage. if i remember I will try and have a look tomorrow!

[fad]

Hmm. That's interesting. I would say you either:

Wire the wires to the output of one channel (+ and -) or wire to the positive of both positive channels of L and R (bridging them)

[Rich]

Nov 25, 2017 21:38:53 GMT fad said:

Hmm. That's interesting. I would say you either:

Wire the wires to the output of one channel (+ and -) or wire to the positive of both positive channels of L and R (bridging them)

I'm gonna try both to one channel, but I don't think both to + as the labeling specifies one as -

[fad]

Nov 25, 2017 21:47:46 GMT Rich said:

Nov 25, 2017 21:38:53 GMT fad said:

Hmm. That's interesting. I would say you either:

Wire the wires to the output of one channel (+ and -) or wire to the positive of both positive channels of L and R (bridging them)

I'm gonna try both to one channel, but I don't think both to + as the labeling specifies one as -

Sorry yes. You're right there because - is a common earth.

[Rich]

Nov 26, 2017 9:36:22 GMT @automatik said:

Nov 25, 2017 18:52:37 GMT Rich said:

...
I have 'R Signal in +' and 'R L Signal in -'. Would you say that the wiring piggybacks off of one speaker channel or both, the + of one and the - of the opposite side, to create some kind of balance in sound? Any help gratefully received, as you can see the nephew is wanting to get it installed in his dad's car!

Can it be that one of the labels was cut wrong and it should read Rear Right signal in + and Rear Left signal in - ?
Cause that´s what real* subwoofers were connected to amps ready for impedances below 4ohms back in the days.
Here you have an active sub that just requires a signal and since it´s just an additional bass, it is fed with a so called sum signal.

* I used the term real (subwoofers), since I´m a bit skeptical about the result of your sound improving efforts. Surely a 5" (=13cm) speaker makes some deep tone noise - if you only have a pair of 3,5" (=8,7cm) speakers in the dash e.g. You will be able to hear a difference - if the car stands with the engine off.
But while driving the car will produce enough deep frequencies itself, so the sound effect will get washed away soon.

I would expect the same with that tube up there, although it has a proper speaker at 8" (20cm)! But what most noname amp producers have in common, is the output info! 100 Watts? I doubt it. I guess you can truly expect 20-30W.

It needs more watts to be louder than a cars own deep frequencies and more mebrane surface to speak of a subwoofer. 8" is just the minimum.

Sorry to sound negative, but it really is a question of claims.
You can be satisfied easily, if you have not heard (or felt) real bass, but if you have, you can tell a difference easily.

I'm fully aware of what this is. It's more a gimmick than an actual serious piece of audio kit. Fully aware. Still want to use it because it fits with the rest of the car's ethos. But I do suspect you man be right on the wiring..

[strikey]

sorry...a thorough search of the garage yielded sod all in the way of instructions.

[Rich]

Nov 26, 2017 17:06:18 GMT strikey said:

sorry...a thorough search of the garage yielded sod all in the way of instructions.

Cheers for looking! Everyone's input on here aught to be enough to get it going I reckon.

[strikey]

they will never keep audiophiles happy but certainly fill the sound out a bit. if you are tight on space , budget or inclination to hack the car around too much they are a worthy compromise!

[SmokeEm]

Bass is mono so there is no getting 'Balance' in the sound.

In theory, you should have a power lead, earth lead, trigger feed plus a plus & minus speaker feed. As long as you have the power, earth and trigger feed wired correctly, you can't damage the tube if you wire the speaker wrong. Worse case is it would be out of phase. i.e. pushing when it should be pulling etc. If that is the case (And you'll tell coz it won't be as bassy as you expect) just reverse the two wires.

[SmokeEm]

This diagram shows what I mean - Only one + speaker connection plus one - connection is all that is needed.

[MiataMark]

Nov 28, 2017 11:16:41 GMT SmokeEm said:

This diagram shows what I mean - Only one + speaker connection plus one - connection is all that is needed.

That seems a bit odd to me, wouldn't the filter after the pre-amp need to be an active filter? I thought passive filters were used at speaker level.

[fad]

Nov 28, 2017 16:37:07 GMT MiataMark said:

Nov 28, 2017 11:16:41 GMT SmokeEm said:

This diagram shows what I mean - Only one + speaker connection plus one - connection is all that is needed.

That seems a bit odd to me, wouldn't the filter after the pre-amp need to be an active filter? I thought passive filters were used at speaker level.

Nah not necessarily. Passive is fine, it can just be a low pass and a high pass, likely as simple as inductor and capacitor.
All inactive crossover is,is a crossover with an amp at the end of the day.

[SmokeEm]

99% of active Sub's have a low pass filter built in.

[fad]

Nov 29, 2017 7:38:26 GMT SmokeEm said:

99% of active Sub's have a low pass filter built in.

Yup. No point in amplifying signal you don't need

[squonk]

Nov 28, 2017 11:16:41 GMT SmokeEm said:

This diagram shows what I mean - Only one + speaker connection plus one - connection is all that is needed.

I'm afraid that the diagram you have posed bears no relation to what you are saying as it shows a sub working at line level - completely different to this one. The cables shown on this bass tube are not line level. If they were they would be screened and most likely terminated in RCA (phono) plugs.

Great care has to be taken when wiring up a speaker level output/sub input. If you get it wrong you could common or ground the speaker output of the head unit. In the old days on a low power set this wasn't a problem as the speaker negative was at ground potential. However, the higher power sets we have today have a BTL output which must not be grounded. Doing so will result in damage to the output stage.

Essentially what you are saying about connecting up the sub is correct. It appears to be wired up using the Haffler principle that was originally conceived to extract a rudimentary surround sound signal from a stereo amp. It does this by looking at the difference between the left and right channels. This bass speaker appears to utilise the same system to obtain a complete stereo signal incorporating the bass end from just two wires connected to the head unit. Eg, The cable marked '+' goes to the '+' speaker output of one channel and the cable marked '-' goes to the '-' speaker output of the other channel.

I have to disagree with you about bass being mono. It isn't but our perception of lower frequencies makes it difficult to determine where they are coming from. Most 'mono' subs either use a dual voice coil (one per channel) or a summing amplifier that 'adds' both stereo channels together. We have been conned into this belief of mono bass by the plethora of single bass unit surround sound systems on our TV's!!

Nov 28, 2017 16:37:07 GMT MiataMark said:

That seems a bit odd to me, wouldn't the filter after the pre-amp need to be an active filter? I thought passive filters were used at speaker level.

Line level filters are designed to work with a high impedance load (eg between head unit amplifiers) whereas a passive filter (crossover) is designed to work at a lower impedance (eg speakers). Line level filters feeding multiple amplifiers gives greater flexibility and potentially far better sound quality. Whilst an amplifier for a bass speaker requires a high output with good damping (say for example, 200w), an amplifier for the HF speakers will only need to produce 10's of watts but be of a low distortion design to get a good balance of sound when used in conjunction with a 200w bass amp. It's a bit like brains (High Frequencies) Vs brawn (Low Frequencies)!!

If you are using a single amplifier feeding into a passive crossover and then the speakers, the amplifier has to try and do a good job of amplifying all frequencies between 20Hz and 20kHz. A difficult thing to do well.