Rythmik 15 Red Oak Sub build

Very interesting design for a "grille" I like it a lot, very unique! Well done!

I use one also. Its front firing though., I always wanted to do a down firing as I heard the bass is less localized. Any truth to that ?

I like the exterior finish,very nice work on the covering ! The driver protection unique.

Not really.I use quad 15" and they face forward, not a sound (um..I can't localize them)

But does downfiring help transfer energy into the floor (instead of shaking the cabinet)also giving the effect of more or less localized bass?

Just thinking out loud here.

Sub looks great man. Love that finish too, don't have the facilities for that so I just stuck to Red Maple Vinyl Laminate from PE. Closest I can get to a beautiful finish like yours.

Great job, nice build.

I think it looks great!.. nice work.

Here are the photos of the new amps. Same output, additional features.

w/ PEQ



no PEQ, but with XLR and master/slave control for multiple amps.

sorry to ask this - but how did you achieve the wonderful grain (after staining) if the cabinet is made from mdf?

sub looks awesome

So that looks like a single band PEQ. What's the price increase if any? Maybe I need to convince my wife I need one now!

By the way OP, great job on the sub build.

XLRs! Just goes to show - customers talk, Brian listens, Brian acts!

Nice amps Brian!

Rolandtk wrote...

"Update - per emails with Brian, the new amps are in the country! Once i get the PEQ amp, i will post a review and photos of the sub in play."

Great news rolandtk, Thanks for the update I will watch for your eval.

Do you, (or anyone) have any idea if when going with two Rythmik sub kits, would having one amp with PEQ and one with XLR be the way to go?

Thanks for any repy.

Interesting.

Hopefully soon- Brian from Rythmik Audio will be able to fill us in on some of the particulars.

I cannot really demo all these features without showing the plots. SO here they are
A370PEQ:

On the top is this defeat-able PEQ. The gain level is from 3db to -12db. The bandwidth controls how wide the notch/peak is. Frequency is from 20hz to 80 with each dot position represents 10hz increment. I don't recommend boost below 35hz. But boost above 40hz is ok as our subs
have more headroom there. The first plot is the gain control at 3 different positions: 3db, 0db, and -12db. The frequency setting is at 20hz. the bandwidth is at min.



Here is another plot shows how other positions look like.



As one can see, the most useful range is between 0db and 3 o'clock position.

Next is the width control. The comparison is between 7 o'clock, then 9, 12, and 3. I didn't plot 5 o'clock as it is same as 3 o'clock position. The gain is at -12db and frequency is set to 20hz.



Next is the frequency setting comparison at various dotted positions, from 20hz to 80hz. There is a bit of inaccuracy. But overall it is still very good.




In the middle are our regular controls. The one worth discussion is the phase/delay. It is same as the previous one except I improve the resolution and change the label. The circuit is a simple RC all pass filter. Similar circuit is used for adding delay time (such as those in Linkwitz's all active speakers). That is why I add delay to the label. While the circuit does provide delay, but it will top out at 180 degrees. Theoretically, given a fixed delay, the phase shift should be proportional to frequency. However, this RC circuit will not go beyond 180 degrees. Even though I can cascade more stages, I don't think it is useful. I put in 180 there to stress the fact that the circuit tops out at 180degress. So that 180 degrees is not constant to all frequency. Even if you put in 90degree (at 12 oclock position), that is not constant for all frequencies. To get accurate phase delay, one really needs to first figure out the xover frequency and the reciprocal of that gives use the period. 90 degrees is a quarter of period. Then find the position of that on this dial. Your adjustment range is from 7 o'clock to that position to get 0 to 90 degrees shift, you can more by turning more to the right, but it may saturate at 180 degrees even before you turn all the way to the right. Anyway, a plot is worth a thousand words, and here it is from 8 o'clock position to 3 o'clock position. I only plot to 3 o'clock as there is no change beyond 3 o'clock position.



The bottom row has 4 switches. The left 2 are new. One is to replace our 12-24db switch. So this model will replace our 12-24db model going forward. For those with HT receiver and use its bass management, they should get it to middle position 12db/EXT. EXT means the main xover is external. For those don't have HT receiver, or don't use the bass management function on receivers should use the top or bottom positions. The xover control in the middle row now becomes the fine tuning knob. The rumble filter is for vinyl user or those who wants to play louder. It is a 3rd order HP at 20hz.



A370XLR:

It has a balanced input and balanced output. However, the balance input is more for subwoofer input only as it does not have HP output. The balanced output is mainly for master/slave configuration. In master mode, the balanced input is just like the other two single-ended inputs, except it does not have HP filtered output. The balanced output goes to another slave unit with the switch set to slave. With this setup, one can precisely control two units to have identical output except phase. In other words, phase control is still functional in slave mode. I believe this is desirable as multiple subs may have different distance to the listener.

I purchased the DS12CV with the 24db adjustable slope kit last year in November.
This amp with the peq interest me though , is there a way i can swap my existing one for this one? or is this amp only for the 15" kits,
I have it loosely mounted in an external box so i can easily take it out.

The entire A370 series amps are compatible in terms of footprint. Their sink heats are identical (EDIT: I meant mouting holes, fins, corner, ...etc). Servo power amps are identical. The only difference is the preamp board. If we compare the entire servo plate amps between the 12" and 15", there are only two places that are different: 1) the field replaceable servo board, and 2) a resistor-capacitor network that is soldered to the back of the preamp. By changing these two things, one can convert the amp for use with one driver model to for use with another driver model. The reason why the servo board can be different is that we can compensate for the physical parameters of each model such that all models have matched frequency response between 5hz and 60hz (+/-1db the worst), although I prefer to refer to it as FR cloning. So my customers often ask me if 15" plays lower and my answer is "no". They actually have the same FR in the above frequency range as the 12" driver in order to preserve the same time domain characteristics. The 12" may not play as loud and the extension switch is there for the purpose of trading off max SPL with extension.