[AlexH]

My system is used for both HT and music. When I want to listen to music I use my Oppo 203 connected directly to my amp, bi-passing my processor. I then can use the Oppo to control the volume. The Oppo is connected to the amp via rca cables, which is then connected to my X-statiks. The X-Statiks are used for music only.

 I plan on adding an OB sub with the HX300 amp soon. One sub for now and then add another next winter. I was planning on adding a high pass filter between the Oppo and amp. I would also like to run the sub mono by combining to left and right outputs of the Oppo.  So now to my questions. Should I combine the outputs of the Oppo?  If so does this layout look correct?

[lincolnmat]

Doesn't the Oppo have bass management? Can't you define the crossover point and it will not send the lower frequencies to the amp/speakers?

[lincolnmat]

I have the 205 and it allows you to set the bass crossover frequency between 40 and 250 Hz. You have to set the front speakers to small to get the bass management. I checked the manual and the 203 has the same controls.

[AlexH]

It does have bass mgt, and that was my first thought as well. I was told to avoid the bass mgt and go the route I posted, not from this site. Your thoughts?

[Danny Richie]

Just plug this into the back of your amp:



The cap value needed depends on the imput impedance of your amp and where your target -3db down point is for your main speakers.

The RCA at the top is just a loop with no filter. It can go over to your servo sub amp.

Danny

[Rock Ball]

I will be building an Elekit TU-8600S 300B SET amp.  The input impedance is listed as 50 Kohms.  I will be using it with my NX-Tremes and A370PEQ subwoofer amps.  I found an online RC high pass calculator.  If I choose a 60Hz crossover frequency, it calculates the capacitor value to be 53.05 nF.

My understanding is that I will be taking a load off of the TU-8600 amp by not feeding it the lower frequencies.  Is that correct? 

For those of you who have a TU-8600, what is the best crossover frequency for getting the best low frequency from the amp?  I've read that the lowest frequencies are not a 300B amp's strong point, so I'm thinking that the A370PEQ can cover the range.  I know the NX-Tremes can handle them, so this is mainly for getting the most from the TU-8600 amp.

EDIT:
I should have entered available capacitor values instead of a desired crossover frequency, since capacitor values are limited.
0.100 uF -> 31.83 Hz
0.047 uF -> 67.73 Hz
0.033 uF -> 96.46 Hz
0.022 uF -> 144.69 Hz

[Danny Richie]

Keep in mind that those cap values are giving you a -3db down point.

Where you are crossing to the servo subs is where they are each 6db down.

You also have a natural roll off of the NX-Otica.

And that is a really nice amp. I can tell you all the things to upgrade to really get the most from it.

[Rock Ball]

Danny, what value of cap do you use with your amp, triple subs and NX-Tremes?

I'd like to hear the details about your amp upgrade.  I'll start another thread for that, if that's OK.

[Danny Richie]

Danny, what value of cap do you use with your amp, triple subs and NX-Tremes?

I'd like to hear the details about your amp upgrade.  I'll start another thread for that, if that's OK.

I'm using a .047uF Miflex cap in my pre-amp on one of the outputs. And I use it most of the time with my open baffle speakers.

[Rock Ball]

I made some measurements after building a High Pass Filter (HPF) circuit using a 0.047uF capacitor.  I included a bypass switch.

Here are my measurements of the left channel only with the sub turned off.


L + sub, no HPF:


L + sub + HPF:


L channel with and without HPF:


As a point of reference, here's an older left channel measurement from 5/24/2020 with my Denon AVR and no HPF circuit:


That old measurement LOOKS better to me, but the 300B amp sounds so much better.

[mlundy57]

I consider measurements as a tool to help get the sound you want. Let your ears be the final arbiter for what you like.

[Hobbsmeerkat]

You listen with your ears, not your eyes, so even if they don't appear to measure as well, but it still sounds better to you, then you're on the right track.

[Danny Richie]

Man, that left side is pretty smooth.

You have a slight peak at 500Hz or so that could be a side wall or ceiling reflection. Try to figure out where it is coming from and then you can figure out a way to knock it down.

Try pulling the speakers forward slightly and see what happens too.

The gradual roll off of the top end is typical of a room response measurement.