Spatial Audio Raven Preamp

Good cores are essential for low distortion.

Capacitive coupling exists between windings regardless of the quality of the transformer. For this reason alone its important for the transformer to be loaded correctly so it expresses its winding ratio without inter-winding capacitance as a parallel element. Otherwise the frequency response won't be flat.

@donsachs @lynn_olson The Blackbird Monoblocks and Raven Pre have over thirty hours on them and how sweet they are. Great job gents.

But darn it Don right you are about the Khorns and lower base. Running Roon I have even gone into the paramedic equalizer (a sin?) and boosted the lower hertz but still compared to my other system w/ a pair of Sonus Faber Guarneri Evolution’s speakers (faster sounding than Khorns) the base is flat verses the aliveness and vibration of a nice walking bass line. Low piano notes should vibrate too. “Grandmama's Blues” by Cyrus Chestnut on the "Earth Stories” album is a great test track https://open.qobuz.com/track/2003813  or even “Ham Hocks and Cabbage” by the Christian McBride Trio https://open.qobuz.com/track/10462550. Lower Tom drums also not quite there.

The low mids..heck all the rest (room still not treated and it’s boomy ) get ‘er done. Your gear is great and my contact over at Spacial has provided great service.

I have to consider if’s my streamer adding/subtracting to the bass quandary. I’ll swap out my other streamer and dac.

@wsrrsw

It will not be the amps unless something is wrong with them or you have a bad tube. The easy test is to move them to your other system. Your Sonus are 86 dB, 4 ohm. Not the best load, but the blackbirds will drive them and that will tell you if the amp has issues. Khorns have limited bass below about 45-50 Hz. It falls off like a stone. They are what they are..... They do other things quite well. The crossovers can be upgraded if you have not, but the physics of the speaker in that cabinet are what they are.. the spec is 33 Hz, but that is - 4dB. It is an incredibly easy load for the amps. If you have the patience, put the preamp and amps in front of your other speakers and see if you are satisfied with the bass. I suspect so. If not, then you may have a tube that didn’t ship well. My guess is it is a combo of the Khorn and the room they are in.

The first thing people say when they hear the Raven and Blackbirds is how amazing the bass is.... and your speakers are trivial to drive.  The amps hardly know they are connected.

@wsrrsw

Also, yes, in my experience the streamer has a huge effect on things.  So play around.  The Raven will happily use RCA inputs, but your best performance will most likely be with a DAC that has XLR outputs.  Then you have an entirely balanced system through the amps all the way to the speaker.

@wsrrsw You have an ideal situation for using subwoofers. You might look into something called a Distributed Bass Array which is the use of 4 subs placed asymmetrically in the room so as to eliminate bass nulls and peaks in the room. This is often particularly noticeable at the listening position if the room has regular dimensions.

My main speakers are flat to 20Hz yet I have no deep bass at the listening position in my room. So I use a pair of subs to break up the standing waves that cause this problem. One is to my left and the other slightly to the right and behind me. Both are as close to the wall as I can get them.

In your case since your speakers don't go much below about 45-50Hz, you are an ideal candidate for all 4 subs. The Swarm from Audiokinesis is an ideal candidate for this since they are meant to be placed directly against a wall so as to be out of the way as possible. The subs are designed to roll of at 3dB per octave starting at 100Hz going down. The room boundary effect provides a +3dB/octave boost, so they are flat to 20Hz. They are 1 foot square and 2 feet high. I have the 10" drivers actually facing the wall so as to maximize the room boundary effect.

The idea here is to run them no higher than about 45-50 Hz, at which point its very easy to get them to blend seamlessly with your Klipsch speakers since below 80Hz in most rooms the bass is already entirely reverberant before your ears can sort out the bass notes being played. As long as the are not allowed to go too high they won't attract attention to themselves- the main speakers will convince you the bass is coming from them via the harmonics of the bass instruments.

It will be easy to get this setup to integrate with the Spatial amps and preamp. Then you will hear how much bass is really there and not only that, you may find that the mids and highs get more relaxed and detailed due to how our ears alter the tonality we perceive when part of the spectrum is missing. So getting the bass right calms down the mids and highs.