Thiel Owners

Hi y'all,

Been enjoying semi-regular lurking on these pages.

Maybe this is plain enough and not in the scope of the discussion about other creative ways one might get or get close to good SSx time alignments. I have a pair of 3.7s mated with a pair of SS1s positioned behind each a couple of feet. I use a Behringer DCX2496 (Ric Schultz modded) as a crossover controller (ahead of power amp and SS1s) plugging into the SS1s normal inputs.

I have chosen a second order filter slope at 80 Hz. Second order as a compromise between the Thiel loved first order and thinking to get the energy to fall off a little quicker to avoid much power going to the passive radiators—maybe muddying the possibly purer SS1 lows.

I looked at the (main speakers) delay that would be by calculations appropriate for a sum of the SS1 behind positions and the delay at Xf for the second order slope. I dialed in that number and tweaked it (only a small amount needed) until the SPL response at 80 was peaked indicating good time alignment there. (and of course set the relative levels by looking at plots of low frequency sweeps)

Seems like there may be a couple of nuances to this line of thinking that I’m neglecting to recall but w/o digging back into my couple years old notes, that is the essence...

I have been pleased with the results. Bass is well integrated sounding, particularly on transients and particularly when compared with either a DCX zero delay file or the fourth order behavior of the Thiel PX05s I started with.

Cheers, John

Hi tomthiel,

Yes, quite a few well regarded speakers over the years/decades have used/still use second order crossovers to the woofer. Given the nominal 180 degree phase delay, the most satisfactory results are generally gotten by inverting the relative phase of the wires to the woofer. This works well for some frequencies away from the fc but not so good for time alignment in the vicinity of fc. Here (with time shifts available) I’ve stood that on its head a bit by not inverting and delaying to seek best phase blending at fc.

I may be telling you a bit more than I know for sure, partly as discussion stimulation. (smile) It has been a few years since I looked more carefully at it. I just reviewed some old modeling spreadsheet work where I was showing myself that if I differently pro-rated or scaled the importance of the time alignment at frequencies stepping away from fc in half octave jumps, some of those schemes would start to suggest I might be better off with something headed toward an additional 35 degrees or so of phase shift. I thought that result was pretty small for how highly speculative I was being… and decided not to pursue it even as a listening experiment.

The overview message is still that, if one is willing to go there, DSP devices give us some greater freedoms to customize that integration than we’ve had in the world of analog crossovers.

Yours, John

Hi tmsrdg, all,

I have two PXOs configured for the 3.7s. (running a pair of SS1s in my case) They worked well but in my room I decided many years ago to go with a Behringer DCX2496 (Ric Shultz EVS modified) to allow more customized crossover control.

(I also have one non-functional other PXO that Thiel and/or their retailer decided to abandon in place and replace rather than repair. I honestly can’t recall if that one is set for the 3.7 or the 3.6s that I had when starting with the SS1s.)

I have procrastinated about offering them for sale.

Yours, John

Hi Jafant,

Current goodies feeding the Thiels: VPI HW-19 Mk4 TNT, and SME IV.5i arm, both with various DIY hot rodding mods**; Soundsmith Strain Gage cartridge and pre-amp; Marantz CDR510 CD; Some HiRes digital files on the Mac, through JRiver Media Center S/W; Nelson Pass Adcom GFP-750 passive pre; Ric Schulz EVS modded Behringer DCX2496 for subs Xover and time alignment parameters only; PS Audio Stellar M1200 power amps; Thiel 3.7 mains and Thiel SS1 subs; Cables a mixture of Audioquest and Cardas; Aux reference: Stax Lambda Pro phones.
(**some mods documented in detail on AudioCircle — links available on request)

Yours, John