BillFitzmaurice.info

My question might be too simple.
My setup is Receiver -> minidsp (+5 boost below 30, -5 about 30) -> Sub amp.
This is then calibrated by audyssey. And then audyssey EQ is enabled.

You may find that Audyssey may be working against you and that you're better off running in "Pure Direct" mode from the receiver (where all tone controls and EQ are bypassed).

I've been (and still am) fussing to integrate my two THTLPs. Although I'm not using a MiniDSP, each of the THTLPs has an SPA250DSP plate amplifier whih provides some DSP capability. The YPAO (Yamaha's equivalent of Audyssey) in my receiver made the job more challenging as it fought me by trying to impose it's own frequency/SPL curve.

I've been using REW to measure the system. It's complicated, but an absolute gem of a tool.

I'm still working on my set up. What I've learned to this point is that I overlooked room treatment in favour of DSP. I'm now focussing on adding bass traps and will see what difference they make.

JensToft91 wrote: ↑Tue Mar 29, 2022 1:47 pm I'm happy to report that 20 Hz horn extension has been achieved! And way, way, way cleaner than the PC12-NSD.
I won't make a review until I've dialed it in - as I know I'm having amplifier - issues.
Playing a -3db 20 Hz sine wave - with audyssey EQ enabled(boosts the low end), the signal clips at -23db on the marantz. The amplifier is only putting out 6 volts at this stage, and I'm able to turn the knob on the board-amplifier all the way to 16 volts before the amp is giving in.

It the solution to lower the subwoofer-out on the receiver as much as possible, and then turn up the sub-amp to compensate?

This is known as a gain issue in the pro-world, right?

JensToft91 wrote: ↑Wed Mar 30, 2022 9:18 am My question might be too simple.
My setup is Receiver -> minidsp (+5 boost below 30, -5 about 30) -> Sub amp.
This is then calibrated by audyssey. And then audyssey EQ is enabled.

Jens, I'm not super clear what your problem and question is.

Is it that, when an auto tune feature is engaged, the reveiver runs out of headroom before the sub amp, even though it's a frequency the receiver isn't actually amplifying?.. and you want to know if increasing the sub amp gain would allow more sub output before the receiver clips?

Is that accurate?

Dave - I know all about REW already, and has the multeq app to adjust what audyssey is doing to my system. I got full controll hell, audyssey wrote my THT off as as 40 Hz subwoofer and rolled it off. That's why I had to implement the minidsp to tell audyssey, that this is definitely NOT a 40 Hz sub.

Seth - nope. It's a subwoofer-preout issue. I think all the audyssey boosting is clipping the receivers maximum RCA output.
I turned the subwoofer down to -10db, and then turned up the gain on the amp. Now I can hit the full 16 volts at -5db on the receiver, before the sub amp is clipping.

My problem before, was that I got distortion at -23db on the receiver, but the sub amp was only putting out 6 volts. Hence this was a signal issue. The RCA signal was maxed out at -23 dB (below reference level)

I hope I'm making sense.

I'm getting about 106 dB at 20 Hz at the listening position, with a 50 w board amp. Umik1 calibrated mic.

Super happy with the THT - It does everything i want it to.
I measured about the same output with the PC-12NSD, but that was at it's absolute limit. All i could hear was portnoise. Like - I felt bad about sweeping it at that level - it didn't sound good at all - but knew i could do it because it has a limiter.

It probably deserves a better amp - but no. This will probably stand as the cheapest THT built

I enjoyed your build and content. Thank you for sharing.

Thank you ACUA.

I will be signing off now - I find myself checking the internet too often - And I'd like to break that habit.
I will enjoy my finished system now - the THT is a perfect fit. Thank you so much Bill - awesome design - delivers as promised.

Thank you for all your answers. And a little special thanks to you, Seth - for understanding my constant search for information.

Cheers

JensToft91 wrote: ↑Fri Apr 01, 2022 12:37 pm I will be signing off now - I find myself checking the internet too often - And I'd like to break that habit.
I will enjoy my finished system now - the THT is a perfect fit. Thank you so much Bill - awesome design - delivers as promised.

Thank you for all your answers. And a little special thanks to you, Seth - for understanding my constant search for information.
Cheers

Oh man, we don't get many goodbyes in here. Made me think of this:

https://youtu.be/nXaEf4ktpPA

JensToft91 wrote: ↑Fri Apr 01, 2022 12:37 pm ...And a little special thanks to you, Seth - for understanding my constant search for information...

Completely my pleasure. Thanks for the oportunity and for sharing the adventure.

Can't cheat you for final implementation pics. (Only need to finish the cover)
I can't really describe why this sub I so much better than all the others that I've had. It even fills my room better, even though I know the room modes should be the same.
But I don't need to know. I just love this sub.

It still cracks me up (in a "that's amazing" way, not a "ha ha that's ridiculous" way) that you're getting everything you desire in the room with that puny little insignificant board amp. Really Jens, it's pretty cool in my book of what's cool.

JensToft91, really good to read your report. Question, are you able to provide a higher supply voltage to that board amp? I know that on some boards, one is able to run anywhere from 12v, right on up to 36-48v. Just curious.

24 volt support it clips at 16 volts. So it can provide around 50w. The sweep I posted is at 14 volts or so. With an 18 Hz highpass filter, which I have lowered to 14 Hz if I remember correctly. I got a little notch more at 15-18 Hz, but not anything audible. I added the highpass, because I only hear higher harmonics if it attemps to play the lower notes at full tilt. Will never really happen - but it shows through in the intro to Edge of tomorrow (be careful if you try it with dynamic EQ on, it will send your driver flying)

And Seth - this is even a 2.1 amp, so it's three times bigger than necessary. 2/3 is satellite amps.

What kind of amp is that? It looks so....small...

Joe

Similar to these:
https://www.soundimports.eu/en/audio-co ... oard%20amp

You supply them 12-36 volts. It's a chip amplifier