Old amplifier Adding active sub advice

Chazz83

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I have been building a retro 1990s hi fi for my music enjoyment I have a technics tuner from 1989 am fm and a jvc ax-e71 powering some mission m50 bookshelf speakers and I have been using it for a month and have been enjoying the sound but I have just felt something has been lacking and now I have finally discovered it is the lack of low deep bass at low volumes. I have an active sub and attached it the way I found on google through speaker wires, And this solved my problem but there was way too much bass. Even when I had the amplifier bass level turned right down it was still overpowering the other sounds. Has anyone got any advice how I could control the level of the subwoofer to turn it down to a nice subtle edge. The sub has a single rca input. The amplifier has no subwoofer output. I would be very grateful for any advice on this.

I have searched google and have seen line output convertors and things but mostly for car audio. And I have no problem with the amount of bass I just want a way to control it and reduce and increase as needed.

Thanks
 
Connecting via the speaker wires should alter the volume of the sub with the volume control of the amp. Typically you connect the amp to the subwoofer and the the subwoofer to the main left/right speakers, circuits in the subwoofer manage the crossover of the two.

The usual way to set it up is to have the crossover at the 3db roll off point on the main speakers - for Mission M50's that looks like 65hz, you then dial in the volume of the sub (should be a volume control on the sub) so you can bearly hear it and then adjust +/- to taste.

As above knowing the sub make/model would help.
 
Without knowing how you have connected the speaker wires, it's difficult to help, but I assume you have the volume or gain control on the sub turned down as low as it will go?

If it's still too loud, a passive attenuator will probably do the job. This will be fine:
Amazon product ASIN B076DBCGB5
 
Thanks for the helpful replies the subwoofer is a philips active sub woofer only one input a single phono rca. There is no crossover control on it. the volume of the sub would go up and down with the volume control due to be connected to speaker terminals but the bass was too over powering. Thanks Noiseboy72 Have ordered that passive attenuator am hoping that will be able to reduce the bass level to required level. If Not I will, have to have a re think.

Thanks for all the replies sorry for my lack of knowledge on this I am just recently getting back into retro hi fi after years of mini hifi sytems.
 
Update I fitted the passive attenuator and I now have very good control of volume from the subwoofer and the sound is good but I feel the sub is doing all of the music and not just the low bass i even heard vocals out of it. It`s good sound but I want better so I am thinking of a device that I can add to make the subwoofer only get the low frequencies. Any links to suitable devices would be gratefully received.

The other question I have is I bought the JVC AMP AX-E71BK From ebay and it did not come with a remote control. the amp has a ir receiver And I have searched the internet high and low for a replacement remote control and cannot find one anywhere. Is there a work around from mobile phone or does anyone have any ideas where I could get a replacement remote control?

Thanks again for the help the item that was shared here works perfectly and has improved my listening enjoyment massively.
 
Sorry? how can you connect the amp output terminals to the sub if the sub has only 1 rca connector, I don't get it. The rca connector on an active sub is designed for use with an amplifier with a dedicated subwoofer rca output. Have you connected the amp speaker terminals directly to the speaker inside the box? am I missing something here? Is there a model number on the subwoofer?
 
It sounds like the internal filtering on the sub woofer is set quite high. Are there any "crossover" controls on it?

If not, you would be best to get a better sub with this feature, as adding external filtering is possible but not really worth the effort.

What is the sub model number? Was it sold as a sub or as part of a system which had it's own main speakers as well? These Sub-Sat systems tend to operate at a higher frequency than conventional subs.
 
Thanks for replies the sub is a philips from a old surround sound system we had connected to tv via its own amplifier it had 6 small speakers with it.
 
Sorry? how can you connect the amp output terminals to the sub if the sub has only 1 rca connector, I don't get it. The rca connector on an active sub is designed for use with an amplifier with a dedicated subwoofer rca output. Have you connected the amp speaker terminals directly to the speaker inside the box? am I missing something here? Is there a model number on the subwoofer?
I bought a single rca to double rca converter lead and then that goes to the level control and then the wires are connected to the speaker terminals on the back of the jvc amplifier.
 
Hmm...
OK, so 2 problems I can see there.

1. The RCA adapter is joining (shorting) the left and right signals together. This means that you now have the amplifier channels joined together and will be getting a mono sound from the main speakers! Move the RCA joiner to the other side of the volume control and this will provide enough isolation, as the resistance in the control will prevent the direct shorting out of the amplifiers

2. Your sub is designed to reproduce a wider range of frequencies. This is to support the smaller satellite speakers and is why you are hearing the low end of voices as well as the bass slam. The fix for this is a low pass filter (LPF), but as a passive device, building this as 3rd order would be quite complex and I'm not aware of an off the shelf option. You would therefore need an active filter - which on its own would cost more than a new sub with the correct controls and speaker inputs!

My suggestion: Ditch / sell the existing sub and save your pennies for a decent one with the right controls and inputs. You will be 100% more satisfied with it in the long run!!
 
Ok Thanks for the replies. I am going to abandon this subwoofer and invest in a used good quality one. One that has plenty of controls on it so i can connect direct to amplifier through the speaker wire connections. Thanks for all the help.
 

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