Official Rythmik Audio Subwoofer thread - Page 208

Amplifiers have (non user serviceable) trim pots to zero out dc bias if that is the problem and not a component. DC makes a thump when you turn the equipment on.

To be clear here, you can't zero out a DC bias on the AC power by tweaking the amplifier's output offset. Different port--power port versus audio output port.

I am aware of that but dc offset on a powerline is highly unusual and the method for discovering ground loops should reveal the source anyway. The links I posted also discussed isolation transformers, decouplers, high pass filters etc. Ignore them if you wish. DC does not make a hum.

DC does not make a hum.

No, but if it is an offset on the power, it can cause a buzzing noise due to magnetostriction as the transformer's magnetization flux collapses as it is driven in and out of saturation by the alternating current. The noise won't come out of the speaker, though--it will emanate from the transformer's core.

The link to Tripp's isolation transformers is worthwhile.

Incidentally, the problem of power DC offset, while rare, has received significant attention on the web. There are schemes using capacitors (they have to be large), resonant filters, and both in combination with offset diodes to minimize the noise. I just mentioned the isolation transformer because it is so simple conceptually.

Another thing: The transformer doesn't need to be rated for the peak amplifier power. It can be rated for rms average power over some modest interval. Drawing more current from a transformer than it is rated for results in heating (and a slight flat-topping of the waveform due to winding resistance), but not core saturation, as long as the current is drawn equally on both sides of the cycle (which it isn't in the unusual case of a DC offset produced by some bad-acting piece of parallel equipment).

Another one here with a dead silent no buzzing from the amp FV15HP. I have had zero issues at all. I just simply have it plugged into the wall. Now that it is in its final location I do need to get some type of surge protections for it. I think as stated above it affects just a very small percentage of the owners. You just hear about that type of thing here (or problems in general) as owners come looking for advise or help with problems they are experiencing.

I would not hesitate one iota in getting the parts for a CI from Rythmik.

Regards,

RTROSE

pearls, thanks for the explanation. Even an isolation transformer is just a bandaid to the problem like using an optic cable to eliminate ground loop issue. The problem is still there , you just can't hear it anymore. If it is DC offset on the AC line then the power company should investigate further. I guess (If he has not done so) is take the sub to another neighborhood to see if it still hums. Is this the sub with the intermittent hum?

Edit: I don't have any hesitance to buy Rythmik either, I'm trying to get 1 now.

Remember, it's not always an issue with the power company. Home appliances can introduce noise/DC offset into the mains as well. See Brian's printer, my wife's curling iron, and that other reference to a Plasma TV. These are all devices that can do it plugged in at your own house.

Sure, the problem I was speaking about was the user that said the problem was coming from his neighbors house. Could a 7.5kv transformer on the street be about to bust a nut? That was why I asked about foggy weather many posts ago. The power company should be interested in line problems. Homeowners shouldn't have to buy expensive isolation transformers. Neither should UL listed devices interfere with other equipment. Wouldn't that make the printer, hair curler etc defective?

Home Appliances always generate internal surge: Washer, Dryer, HVAC, Boiler, Windows AC, Refrigerator, Dishwasher, Laser Printer...dimmers. I would think a whole-house surge protector device with EMI/RFI noise filtering goes along way. Leviton has a good SPD about $299.

I guess I'm just lucky then. Never had a problem with anything in the house affecting the HT. It's on a dedicated circuit straight from the main breaker box with 10ga wire.

Hey Guys! It's been a week now since I picked up the FV12 and I'm still loving it. I have a question though since I am new to the realm of home theater systems. Currently I have the subwoofer set at the 12 o'clock position, frequency turned all the way up and phase set to zero. As far as the receiver settings I have my towers set to small and crossover at 80hz. Am I getting the most out of my subwoofer or do I need to do something different. I mean to me everything sounds great, but I just want to make sure I am not doing something wrong. Oh and this is just a 2.1 system if that helps.

Unless you have small main speaker you don't want to cross above 80Hz because you will start to tell where the bass is coming from. It should sound like all the sound is coming from the mains. You can also cross lower, I have mine crossed at 60Hz but I have large mains that will play that low. Play with it experiment with different settings see what sounds best to you. It also helps if you have a SPL meter to take some measurements so it's not all subjective.

Hmm so I should adjust the crossover on the back of the subwoofer to 80hz? I thought that since I set the receiver crossover to 80hz that basically overrides what I set the subwoofer controls to. I have heard people say to turn the frequency all the way up on the subwoofer and do your adjustment in the receiver. Sorry if this is confusing to you as I have a hard time explaining this stuff

Yes, you are correct. I believe on the FV12 there is no crossover override, so put it up high and let your receiver do it.

I am wondering how the Rythmics will work with planars?
I recently got MMGs which will likely be upgraded to something bigger in the Magnepan lineup. Even though this is a HT setup, the use is primarily music these days due to limited time.
I was looking at the single or dual f15s but is there a different model that would work better?

You should set the crossover on the sub to the highest setting and set the receiver to 80hz.

I've seen several write ups of people using Rythmiks with Magnepan's and they love them say they mate very well. The only ones they use are the F15's. You could use the F15HP but I don't think they are needed. I believe I saw a User write up on the Rythmik site. Maybe somebody that has them will speak up.

Thanks guys for the clarification!

I knew a guy who is using Maggies 3.7 with a F12. It is very subtle and blends in so well. I was at his home last Sunday to enjoy some music since he just acquired Pass Labs X350.5. The F12 is on the right, well hidden in the photo. Also, he is using AntiMode 8033S too.

IF using LFE input on sub, crossover and phase controls are bypassed on A370PEQ3 amplifier. It's irrelevant as to their position.

Use distance setting on receiver instead of phase control on sub-woofer.

He's got the FV12 so it behaves a bit differently. I think you can't bypass those controls so should put crossover all the way up to make it irrelevant relative to the crossover in the receiver.

Sorry. Thought I saw F12 in post.

Never mind.

War of the Worlds should be coming in today via Netflix. I can't wait to finally really test out my new FV12. I will post my thoughts after I have watched it.

That scene will never be the same once you watch it with a "real sub" like your FV12. In fact I'll bet ya that you watch it more than once.

Enjoy!

Regards,

RTROSE

Well my FV15 came today! I must say Brian and Enrico do an awesome job on packing these subs! Double boxed? Yup! But not your typical double box for sure, very thick walls on the boxes, and not to mention the styrofoam packing all around on the inside box! Un boxed it and set it up where my Paradigm was. I've only played about 6 songs from cd's. Patrick O'Hearn and David Helpling and it was great, not awesome just yet, I'll give it a couple of days to break in. But what I heard was amazing! Volume is set to 12:00. I'll be running Audyssey tomorrow am and start playing with the controls. Not going to push the sub just yet. And a question, where do most have their volume knobs set at when running Audyssey or for that matter anything?!

Jeff

I'm really interested to hear your impressions of the FV15 once it breaks in. I'm considering the FV15 or FV15HP to satisfy my upgradeitis once I get the cash saved up.

I'm testing different DVD's (Animusic 2), CD's, and soon some Blue Rays. Right now, without calibrating the sub, I'm hearing a "growl" from some music that wasn't there before with my Paradigm. I can hear it loosening up as I listen more and more. Volumes at 12 and in my Integra DTR 40.2 the sub level is at -3.5. I'll keep you updated as time goes by. Btw..my wife said "I feel my legs vibrating, is that normal"! "I don't know if I like that"! I replied, "well, we never FELT that before because our Paradigm couldn't dig that deep, something we will get used to and enjoy"!

Jeff

Feeling it is awesome isn't it? I know what your talking about as my previous setup did not have near the oomph that the FV15HP does. I hear and feel things that I did not before or even know was there. I think it was Iron Man I was watching and I heard something weird. I thought something was wrong so I did some "research" and discovered that there was some LFE there that I was not getting with my other setup, very cool.

When I run my YPAO I set the sub's volume at 12 run YPAO and then boost the sub setting by about three decibels and turn the volume up to about 1 or 1:30. Just about perfect!

Regards,

RTROSE