Forums - Rythmik Subwoofer Compatibility with Decware Amp?

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Posts: 25

Rythmik Subwoofer Compatibility with Decware Amp?
10/17/24 at 22:57:21

Curious, is anyone using Rythmik Subwoofer? I was about to pull the trigger when I decided it might be wise to ask their technical support team and informed I would need a minimum of 50 watts for the speaker level inputs to work properly.

They stated Tube amps do not have enough power to work with their subwoofers. They explained that a speaker level to line level converter uses a resistance that lowers the input voltage to about 1.5VRms to 2VRms but to get that voltage you have to have a minimum output voltage from you amp. (Wouldn't a preamp address this issue?)

They also stated Tube amps with very low watts produce not enough voltage to get decent input voltage on the subwoofer pre amp then subwoofer output would be reduced to very low levels. I would require a tube amp with more than 35 watts for their sub to work but it would not reach max output.

Honestly, this is all above my comprehension level, but would think that such a limitation would apply to all subwoofers connected to tube amps.

At the moment, looking at the REL T/9x and Kef KC-62 or 92. The REL rep is suggesting the S/510 which I think is too much for my small listening space.

Any input and suggestions welcome.

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johnnycopy

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Posts: 142

Re: Rythmik Subwoofer Compatibility with Decware Amp?
Reply #1 - 10/18/24 at 01:44:08

Hi Craig,

I have for many years run 2 rythmik amps off of many solid state as well as tube amplifiers including a larger carver sep design as well as my current mono tube amps (coincident technologies Frankenstein 300b 8 watt per channel monos)

They franks are seriously overbuilt with power supply energy storage of over 140 joules, so I want to be careful about comparing them to other tube amps (something you can check with Steve on).

I have had excellent results running speaker wire cables from the outputs of my 2 tube amps directly into the 2 rythmik plate amp high level inputs, then onto four 15 inch open baffle bass drivers.

My experience is with peq370’s.

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briand77

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Posts: 10

Re: Rythmik Subwoofer Compatibility with Decware Amp?
Reply #2 - 10/18/24 at 07:07:05

I'm using 2 Rhythmic F12G subwoofers. Why do you need to use to the speaker-level inputs? Just run the preamp output to the subwoofer plate amp. A potentially better solution is to run the preamp to an active crossover (like the Sublime Acoustic) and split off the LF. This has a few advantages. 1) The subwoofer integration is much simpler as you won't need to match the roll-off of your mains 2) Less stress/excursion on your mains woofers (and hopefully better sound) 3) Slightly lower power requirement for the amp. The disadvantage is another device in the chain (and extra cost).

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craigcarter Verified Member Posts: 25	Re: Rythmik Subwoofer Compatibility with Decware Amp? Reply #3 - 10/24/24 at 00:34:23 Hi Brian and Johnny Thank you for taking the time to respond, your comments were very helpful. Craig
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dank

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Posts: 425

Re: Rythmik Subwoofer Compatibility with Decware Amp?
Reply #4 - 10/24/24 at 02:27:52

Something strikes me as very wrong with the answer you got stating you need at least 50w to use the high level input. It implies that you could never turn your system down and still have it sound right, which I think is pure BS. After all, turning the volume down limits the amplifier output to WAY less than 30w...usually sub 1w for low level listening and I'll bet that subwoofer sounds just fine at low levels.

Whatever the reason, I think you got a bum answer.

Dan

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mk60

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Posts: 92

Re: Rythmik Subwoofer Compatibility with Decware Amp?
Reply #5 - 10/24/24 at 03:16:18

Fwiw, Brian, the guy who owns rythmik and designs their subs and has always answered my tech support emails, is a great guy and really knows his stuff. My Rythmik sub does not have high level inputs, so, although I don't personally have technical insight here, I would like to think that there's something correct to what he's saying. he personally came to my house to check the capacitors on my rythmik sub because he was touring around replacing caps on units that he believed to be affected by a bad batch of parts. We ended up chatting about crossovers and the challenges of working with la scala bass bins for an hour and he drew me some really insightful graphs and chatted to me as an engineer not a customer. If you're confused by his response reach out to him, I think he'll be happy to give more insight into what's going on. He cares.

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craigcarter

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Posts: 25

Re: Rythmik Subwoofer Compatibility with Decware Amp?
Reply #6 - 10/24/24 at 20:07:07

I forwarded the initial responsed to Rythmik, and received the following from Enrico noted below. I most say the consumer service is amazing. I am thinking about the FM Dual, but I am also intrigued by the Buchart Sub10.

I do agree with Response #2. (Briand77) The best signal you can send to any subwoofer comes out from Balanced (XLR) and followed by Unbalanced (RCA) pre outs. Speaker level signal is the less clean and the one with higher THD out of the three signals. That’s why we do not recommend using speaker level inputs with any subwoofer.

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Steve Deckert

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If the 1st watt
sucks why continue?

Posts: 6337

Re: Rythmik Subwoofer Compatibility with Decware Amp?
Reply #7 - 10/25/24 at 02:28:58

The THD is relative to the output of the amplifier. Most decent amplifiers at a normal listening volume are well below anything that would be a problem. In fact, with some irony, when you use line level with a solid state subwoofer amplifier the signature of the amplifier remains odd order dominate while the tube amp is even order dominate. Trying to blend these two signatures is like trying to mix oil and water. You have to stir it constantly or it separates. Never can you get the sub to completely vanish. Going high level into the sub allows the solid state sub amp to track and reproduce the signature of the tube amp, including the low level even order harmonic distortion. The result is the sub completely disappears and sounds more natural.

This assumes you are using a tube amp. If your main amp is solid state then we find it works perfectly fine either way. Subs are crossed over a 50Hz so the 'nth degree of absolute purity isn't rendered anyway even if you think you can hear it.

As audiophiles we are so sidetracked by specs and absolutes that we seldom get the sound right unless completely by accident.

Steve

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johnnycopy Seasoned Member Posts: 142	Re: Rythmik Subwoofer Compatibility with Decware Amp? Reply #8 - 10/26/24 at 06:33:43 Yep Steve, heard the same reasoning from so many designers and why I always run the high level inputs indicated in my original response.
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MikeinMontana Seasoned Member Posts: 272	Re: Rythmik Subwoofer Compatibility with Decware Amp? Reply #9 - Yesterday at 15:03:30 We've been using the high level inputs in our Hsu Vtf-3 sub (purchased brand new in 2003) from the Zen. Older sub but man it works beautifully. Our son made sure he purchased a sub that had high level inputs available, knowing he was getting a Zen Amp too. His is an SVS.
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