DIY Rythmik F15HP in Canada - AVS Forum
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post #1 of 8 Old 12-19-2012, 07:32 AM - Thread Starter
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Hello all, first post, after a few years of lurking. I'm starting this thread for all who are considering a Rythmik sub, but who live in Canada. I did a few weeks of research on the net, and finally came to the conclusion (with help from these forums) that a Rythmik sub worked best for my application (clean bass with low end extension, rather than all-out SPL). I admit I was hesitant, as this was my first internet-direct piece of audio equipment. I had never heard a Rythmik sub before, and I was unable to find any professional reviews on the net (other than for the FV15 HP, the ported brother to my F15 HP) I’ve also been stung in the past by UPS with their brokerage fees (that sometimes exceeded the value of the item) and duty and taxes. For all my worries, I was pleasantly surprised.

Ordering:

I ordered the DS1510 driver, and the H550 amp as a DIY kit. The cost was $835 and with surcharges, my total due was $860.67. Just four business days later, I received my package via Canada Post (super quick!) At that time, there was a charge of $29.80 due, for brokerage and taxes. $30 ain’t bad, it just meant a few less beers during the cabinet construction (which was probably a good thing). Total spent to get it to my door: $890.47


Here is the box as it arrived.


I weighed the package on a postage scale, the total weight was 55.6 pounds. Pretty hefty for just a driver and amp!


Everything was packaged very well. There was lots of padding, and things were packed tightly so they didn’t shake around during transit. They included polyfill for the cabinet, although on the site it says they no longer do that. This is the view inside the box, showing polyfill, packing foam, a box for the amp, and the driver box still inside the main box.


Here is the driver, packed in high density foam, and topped with a plastic cover to protect the driver. Very sturdy, and very clean. The driver really is a beauty.


Here is the amp, packed into a box with foam to protect the transformer. Everything fits nice and tight.

Just looking at the stuff in the box was enough to make me mildly aroused, but please repeat after me: “Thou shalt not run in free-air. Thou shalt not run in free-air.” Seriously, I know how bad you want to play, it wants to play too, but it needs a suspension of air so it doesn’t eat itself. It’s worth the wait.

Building:

½”MDF: 3.77
¾” MDF: $35.99
Titebond II 473 ml: $9.99
DAP 100% Silicone: $4.99
1-5/8” Drywall screws (coarse thread): $2.00
Total with taxes: $63.55
Plus Electronics: $890.47
Grand total: $954.02

I went to the local hardware store, and picked up the wood, glue, screws, and caulking for $64. Not a bad price for a box, considering the box provided by Rythmik costs about $400. Admittedly, their box looks nicer, and I spent quite a few hours cutting, screwing, and swearing. I also lost two pairs of pants, due to my own stupidity. However, there is a certain satisfaction in doing it yourself, and definitely gives you a deeper understanding and appreciation of our hobby. Me, I’ve got lots of time and nowhere near enough money, so it was an easier choice. My budget outlay for a new sub was $1000. Tallying it all up my total cost, all in, was roughly $950 plus beer. So, for less than $1200, I got a great sub! smile.gif

I used the “Additional DS1501 front-firing plan” available on the Rythmik site.
The only tools used were:
- powerdill
- jigsaw
- measuring tape, and an old ruler and compass from a geometry set
- hammer (always need a hammer, it just feels reassuring to be able to destroy anything at a moments notice)
- screwdriver
- brain (broken and nearly useless, but still came in handy)
*- a router will be required to do the outside piece on the front baffle that serves to flush-mount the driver. This hole needs to be a perfect circle, because you will always see it. I didn’t have access to a router, so I’ve temporarily left that piece off entirely. No rattles or negative consequences, other than not looking quite as cool.
Sorry in advance, these pictures were taken with poor lighting and poor equipment by a poor photographer. These pictures are worth, at best, 68 words rather than 1000.


Here are all the rough cuts piled up.


Here are all the scrap pieces left over from a 4’ x 8’ sheet.


Here are the internal braces as viewed from the back.


Here are the internal braces as viewed from the front.


Here is the back, just before closing it up.


Ready to drop the driver in, and rock n’ roll!

Special construction notes:

- Buy the right kind of wood. Run away screaming from low-density MDF, that’s not the right stuff. VERY IMPORTANT: double check that the wood is the right thickness. I almost guarantee that the ¾” MDF is not actually ¾”. This will negatively impact the outside of the box. (Guess how I know?)
- Buy the right kind of glue. I used Titebond II on this project. This glue is almost like cheating! I tried a strength test on scrap pieces with and without clamps. In both cases, the wood broke rather than the joint. The pieces were strong enough to swing around and treat roughly after about 45 minutes. Use clamps if you can, because it is a little stronger (about 20%), but if you’re a tightwad like me, just use heavy stuff to apply weight to the joints and you’ll be A-OK. VERY IMPORTANT: Do not wear clothing that you care about in any way. No matter how careful you are, you’re going to get some on your clothes. Your clothes will only be fixable with fire… lots and lots of fire. (Guess how I know?)
- Assemble the internal braces first, then build the box around them.
- The plans are bang-on if you get the DS1501 and 370 watt amp. If you get a bigger driver and amp, adjustments will need to be made. DO NOT finalize your build while you’re waiting for the parts to come in! I had to use a reciprocating saw through the openings front and back to cut clearance for the amp and driver. This was uncomfortable, stupidly dangerous, and made me butcher my geometrically perfect braces. This detail alone accounted for about 80% of naughty words and prayers uttered during the project.


This shows the driver touching the internal bracing, even after cutting a large notch in my brace. This made me sad. “If you let the driver touch the internal bracing, you’re gonna have a bad time.” – South Park

- For better corners, cut some pieces larger and trim to flush afterwards using a router. I don’t care how many times you measure, you’re not going to have perfect corners otherwise. (My corners are terrible, and not fixable, because of the thickness discrepancy noted above. Even with proper stock, you need to account for the thickness of glue and other discrepancies, so work smarter, not harder. If you don’t have a router and a flushing bit, your box will never be perfect. Fact.)
- You can get away with making all circle cuts with a jigsaw (even freehand) except for the outer baffle. The inner braces and inner baffle will never be visible once assembled, your secret will be safe with me.

Listening:

I bought this sub to replace a Paradigm PS-1200 (12” driver in bandpass enclosure, 525W peak power) and to complement a Paradigm Servo 15 V.2 in a 7.2 setup.
I should note that when I received the driver from Brian, it was extraordinarily tight from the factory. Tapping on the driver sounded like tapping on a chunk of Aluminium. After a few days burn-in, tapping on the driver sounds like tapping on a driver. Make sure you use the sub for a few hours before making any judgement. (It did sound awesome right away, but was definitely suspended very stiffly)


Here is the completed sub next to my Servo 15. My box is about one inch bigger in every dimension, for a total of roughly 4 cubic feet after bracing and internals. Note the different types of drivers. Those are Paradigm Monitor 7 towers in the background.

Before moving out the PS-1200, and moving the Rythmik into position, I did some brief listening comparisons. I co-located the Servo 15 and the Rythmik, in an L shape with the drivers inches apart, so as to minimize different room effects, as shown in the picture above. I simply unplugged one and listened to the other, to give (relatively quick) A-B. I do not have any measuring equipment. All the following observations are based on what I heard in my room with my ears, using test tones and other signals. They are therefore subjective, based on MY room, and must be taken with a grain of salt... your results may vary!

Rythmik F15HP vs Paradigm PS1200:

Yeah… this one really is no contest. The PS1200 is a very loud, efficient design. Very good at producing the upper registers, and high levels. Perfect sub for a teenager, as it really kicks you in the chest (50 – 80hz), and will keep up fine with Cerwin Vegas (teenager speakers) The low-end begins to roll off at around 28 hz, and by 22hz, this sub has completely run out of ideas. Low-end distortion doesn’t really factor, due to a built-in high pass that prevents the sub from killing itself even trying to reproduce these frequencies. As such, this is more a well-engineered woofer, rather than a proper subwoofer. It certainly sounds like it in comparison! There was a huge change in the character of the sound when I replaced it with the Rythmik. At first it seemed there was less upper bass (60 – 100 hz), but that turned out to partly be a drastic reduction in second and third order distortion. This seems to be a common thing to really thicken up these areas of the frequency range, as this seems to be what most people consider to be bass. Like a built-in house curve, almost. Many people actively enjoy subs that sound like this, and when presented with flat frequency response, find it unsatisfying and dry in comparison. I would recommend you listen before you sell your previous sub. Combining a Rythmik with a lesser sub would give extended, clean frequency response, while still having that bump in response that some people find desirable. Best of both worlds, although you are re-introducing distortion. Distortion sometimes sounds good, ask any tube amp owner.


Rythmik F15HP vs Paradigm Servo 15 v.2:

When I initially began my search for another sub, my goal was to get another Servo 15. I really love the sound of this sub. It is very clean and well-defined, and has above-average (below?) frequency extension. This unit is pretty old now. The only ones available are pre-abused (used) and very expensive. I wasn’t able to find one that was reasonable during a month-long search. Paradigm abandoned servo tech a few years ago, and use DSP instead now. My best compromise for a near-identical product was the Rythmik, or a Velodyne at roughly 4 - 5x the cost.
The Servo 15 begins to roll off around 22hz, and by 16hz it totally gives up, not even trying. Once again, a high pass filter is used to save the sub from itself. The Rythmik has a user-determined high pass, from none, to 14hz, to 20hz, to 24hz (at differing orders from 2nd order to 7th order). I love having the options available, although it was kinda scary to see the driver pounding away at its stops, but not hearing anything as it tried to do ~5 hz in a movie selection I tried. [War of the Worlds – Pod emergence scene] Some frequencies, rather than just feeling them, I am hearing now [evident in the 16hz fundamental at the end of the intro to Toccata en Fugue re-done by Bass Mekanik].
The sonic character of these two subs is more or less identical. Overwhelmingly clean (the first 30 seconds or so you’ll be wondering if it’s on) and with great low frequency extension. This sub is so clean, it makes Skillrex sound like MUSIC! (No, just kidding, it still sounds like crap) You know that dance tune you like from the 80’s – 90’s with a bass drum beat and bass line at 100 hz? You’ll be thinking “Well, this sub isn’t loud enough.” But the first time you hear a frequency below 40hz, “OMFG!” The Rythmik has audibly better extension in the low end, but is not as competent as the Servo 15 in the higher end. This is due to differing technology; the Servo 15 uses an accelerometer while the Rythmik uses direct voice coil feedback. This is a known limitation of direct servo. The driver also plays a part, as the Servo 15 has a driver that’s essentially all dust cap, while the Rythmik is an inverted salad bowl, making it physically less ideal for reproducing high frequencies. The Rythmik definitely displaces more air, and gives a much stronger sensation of your pant legs flapping in the breeze. I find that using the parametric EQ on the Rythmik to slightly boost 60- 100hz or so (centered at 80hz) makes it quite satisfying, and I intend to experiment with using the parametric to cut from 20- 50hz centered at 35 to achieve a similar effect without boosting any frequencies when I find the time. Loudness-wise, it’s kind of shocking that there’s very little difference between 1500W (4500W peak!!!) and 550W. The Paradigm has a slight edge for going louder, but, really, if you’re getting into this kind of power range, you’re doing something wrong. Move your subs to the proper location in your room and out of a null, or get more subwoofers. Don’t push your subs like that unless you’re doing a Youtube excursion video to show off. Feel free to use me as an excuse to the wife as to why you need more subs! “This Adonis with godlike intellect named bimmaguy told me to…”

Conclusion:

I’m very happy with my Rythmik sub. I made a great choice, and I’m really not known for my good judgement. Surprisingly enough, if someone were to come by and say “I will take one of your subs and buy you another one of the other to replace it”, I would choose the Rythmik over the Paradigm any day. Considering there’s about a $500- 1000 difference between the two, and I have a personal bias towards Paradigm products, I really didn’t see that one coming. Interestingly, one of the subs I also considered was the Paradigm Monitor 12 sub for roughly the same price. Although it supposedly has nearly the same specs (sorry, Paradigm, for the first time I call BS on your specs), there is no doubt I have a better product. I’m a contented customer, and I wouldn’t hesitate to recommend this sub to anyone in the market for a high performance sub. If you’re looking for clean, ridiculously extended bass, then look no further. Honestly, you can’t do better in this price range. If you’re looking for something to pound 90’s dance music loud enough to scare the neighbors pets and hear clearly over the party while you’re making out in your mom’s bed, might I suggest Cerwin Vega.

*Disclaimer*: Maybe it dates me, but I haven’t heard any Cerwin Vegas since the 80’s, when they were the largest and loudest speakers you could get for the money, and were owned exclusively by people with crappy little moustaches and acne. I honestly don’t know what they’re like now. My apologies if you are an owner.
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post #2 of 8 Old 12-19-2012, 07:58 AM
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Sears still sells Cerwin Vega! I don't think much has changed. I remember demoing the big Cerwins at Sears when I was a teen - 1989. Thankfully good sense and good taste prevailed and I got a pair of these Image Concept 200 instead: http://www.stereophile.com/floorloudspeakers/image_concept_200_loudspeaker/index.html

I wish I still had them.

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post #3 of 8 Old 12-19-2012, 08:12 AM - Thread Starter
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I can't say I've ever heard of Image speakers before, but good for you for buying canuck! I'm a little confused, because in the article it says that they were manufactured by Canadian Audio Products International, but the company info is for Klipsch in Indiana? They look nice, what did you replace these with? I'm a big fan of Canadian speakers, the CNRC is a national jem and our gift to the world
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post #4 of 8 Old 12-19-2012, 08:21 AM
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Quote:
Originally Posted by imagic View Post

Sears still sells Cerwin Vega! I don't think much has changed. I remember demoing the big Cerwins at Sears when I was a teen - 1989.

I was stunned to see that but they don't sell cervin vega. Sears is the middle man for selling it from another company. It seems that many companies are now doing this (wal-mart, sears, amazon, etc...) so you have to be careful when buying online because you might not be buying from who you think that you are.

This was directly taken from your link directly under the price:
Code:
Marketplace Item | learn more

Advertised on Sears by a1components.com Seller Rating:
(based on 1 ratings) Also sold by 2other sellersstarting from $649.00
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post #5 of 8 Old 12-19-2012, 02:29 PM
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Thank you,
I’m also a fellow Canadian. For years I have loved the servo 15 v1 but I could never afford it. Your Rythmik F15HP vs Paradigm Servo 15 v.2 is the review that I was looking for. When the time comes I will be buying the prebuilt unit as I will not have the time.

I wonder if you are close to me as I would love to listen first hand.
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post #6 of 8 Old 12-19-2012, 04:22 PM - Thread Starter
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Hi Blacklightning,
Thanks for the compliment. Honestly, I can't imagine why nobody else has tested these units against each other; they're natural rivals. I only wish someone with proper measuring equipment could put some solid figures behind this debate.

I also considered the Servo 15 v.1. This model apparently has very slightly better sound quality. Unfortunately, it had a few things going against it...
- The paper driver is a fair bit lighter than the heavy duty reinforced polypropylene of the v.2 giving better transient response and low-level performance at the expense of almost an inch of excursion.
- It's got a seperate amp module which is a weird shape and size, looks like a DIY as a result.
- 500W vs 1500W... but really that doesn't make a difference. I think 6db with the same driver is the maximum possible gain; but there are other factors that make that unlikely. Oddly, it took owning the Rythmik to hammer that message home.
- Because of its cult status, even badly abused examples can run almost $2000.

One thing I didn't mention in my write-up is that the box Rythmik produces is 3 cubic feet rather than the 4 cubic feet in their DIY design. 3 ft3 is the minimum box size recommended for these drivers, and 4ft3 is the maximum. The larger box will be more efficient in the low-end, and if you have the room, this is a big upgrade and very important for a subwoofer. The only reason Rythmik builds their box at 3 ft3 is to save on shipping costs. You'll notice almost all of their DIY designs displace more volume than the equivalent they sell.
The best option for someone with no garage, or no time or tools, is to buy the DIY kit and download the very well done blueprints off their site. Get a local cabinetmaker to do the build, and apply whatever kind of veneer you want. You'll have a bigger, better looking box, and you'll be stimulating the local economy. I'd be surprised if the builder charges more than $400 to do this, you should save money.
Also, if you buy pre-assembled, shipping is $135 and provided by UPS. UPS will charge you an additional $70 as a bu****it, oops... I mean brokerage charge. Bottom line is, if you pay someone $500 to build you a cabinet, you're getting a better product for less money. So much for free trade, huh?

I'd be happy to have you over if you feel like an ~800 km drive to Winnipeg. smile.gif I really wish there were more Canadians on these forums, especially listed on the "listening buddies" thread where you locate people who are willing to let you come and listen to their listed equipment. That thread is awesome, and I plan to add my profile there.
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post #7 of 8 Old 12-20-2012, 10:06 AM
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Thanks,

I guess I never considered getting someone else to make my box. That’s a great tip. I don’t know much about building boxes nor do I care to learn. I wonder if Salk has their cabinet making instructions. I figure if I’m going to get someone else to do the work I might as well go overboard since I will be picking it up. Weight should not be a problem, as long as it can fit in a standard door.
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post #8 of 8 Old 12-20-2012, 04:13 PM
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The company (API) was sold to Klipsch, it lives on as the Energy brand of speakers. The third API brand was Mirage. Image was boutique, really incredible speaker in terms of bass reproduction in smaller spaces. That was 1990 when I bought them.
Quote:
Originally Posted by bimmaguy View Post

I can't say I've ever heard of Image speakers before, but good for you for buying canuck! I'm a little confused, because in the article it says that they were manufactured by Canadian Audio Products International, but the company info is for Klipsch in Indiana? They look nice, what did you replace these with? I'm a big fan of Canadian speakers, the CNRC is a national jem and our gift to the world

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