Icon Audio ST40 Tube amp and Sub

[Tom_Birmingham]

Hello All, 

 

I am looking to match a Subwoofer to my tube amp, ideally I'd like to stay with Klipsch as this feels right alongside my Heresy II's. I think I have a problem, I have an Icon Audio ST40 MK2 tube amp which only has speaker connects and no sub connection. Is there a way round this with Klipsch subwoofers, if so how do I do this and what is the theory with it ? I have a very small music room, it's not optimal in sound but does me so I do not need a huge sub. Just something to improve the Heresy II lack of sub bass. 

 

Help, thoughts and recommendations would be most welcome. 

 

Happy Monday all x

 

Tom

[BadChile]

There are two possible options both of which operate in a similar manner but require different approaches.

 

1) Select a subwoofer with speaker-level throughputs.  This will have a pair of speaker level inputs and another pair of speaker level outputs.  Wire amp->sub->speakers.  Done.

2) If the subwoofer you select does not have speaker-level throughputs obtain what is called a "speaker to line level convertor".  These are readily available through most on-line sources named after South American rivers, or if handy, you can make you own.  This gets wired in parallel off the speaker taps (one set of wires to the speakers, the other to the convertor).

 

To be honest I don't believe any Klipsch subwoofers currently on the market have built in speaker-to-line level convertors so if you're wanting to stick with Klipsch you're going down the second road.  Which works perfectly fine in my opinion as I'm a similar position in that I'm running two subs off the speaker taps using a speaker-to-line level convertor that cost all of about $10 US.

 

The effect on the audio signal to the speakers is negligible in both cases as the power draw of the convertor is negligible - I didn't notice a change in the least when I wired the subs in parallel, and it should be the case in your scenario as well as the convertor impedance is so low it simply draws an infinitesimally small amount of power compared to the Heresys.  Just be aware in doing so you've now connected two powered devices with speaker wire so you may end up with hum due to ground loops/different ground plans/lots of electrical stuff that frankly I never bothered to understand - I use wireless subwoofers which eliminate the electrical connectivity. 

 

Good luck and enjoy.  And oh yeah: always go dual subwoofers.

[MeloManiac]

7 hours ago, Tom_Birmingham said:

Hello All, 

 

I am looking to match a Subwoofer to my tube amp, ideally I'd like to stay with Klipsch as this feels right alongside my Heresy II's. I think I have a problem, I have an Icon Audio ST40 MK2 tube amp which only has speaker connects and no sub connection. Is there a way round this with Klipsch subwoofers, if so how do I do this and what is the theory with it ? I have a very small music room, it's not optimal in sound but does me so I do not need a huge sub. Just something to improve the Heresy II lack of sub bass. 

 

Help, thoughts and recommendations would be most welcome. 

 

Happy Monday all x

 

Tom

 

I'm not familiar with your tube amp so I took a look at the company's pdf for it. I'm surprised you need a subwoofer for it, it seems such a fine amplifier. Perhaps if you did some tube rolling, you might come to some tubes that don't require a sub?

 

Anyhow, there is another way of doing this, and it is often done: you need a  low-level active crossover: this device will send anything below let's say 40Hz to the subwoofers, and the rest to your tube amp. Indeed, you put this between your source and your tube amp. It will 'unburden' your tube amp, because the lowest frequencies (which demand the most power) will go straight to the subwoofer(s), while your tube amp will take care of the higher frequencies.

You'd have to buy adapter cables because this machine is XLR in and XLR out, not rca.

Something like this: https://www.amazon.co.uk/AVL324-CROSSOVER-FREQUENCY-MOUNTABLE-BUTTERWORTH/dp/B0756HNX8G/ref=sr_1_1?dchild=1&keywords=CITRONIC+cx23&qid=1617046086&s=musical-instruments&sr=1-1

 

https://www.avsl.com/assets/manuals/1/7/170929UK.pdf

 

And for the cables: https://www.amazon.co.uk/MainCore-Sockets-Phono-Plugs-Audio-Black/dp/B079KNSM2M/ref=sr_1_3?dchild=1&keywords=xlr+to+rca&qid=1617045807&sr=8-3