Is H-frame sub using GW-1858 "fast" enough for Maggies?

[MSaturn]

Re: Is H-frame sub using GW-1858 "fast" enough for Maggies?

yes, but slow is wrong. saying the crossover is poorly implemented is much closer to the truth.

[martin]

Re: Is H-frame sub using GW-1858 "fast" enough for Maggies?

Martin,

Of course you could be right, but my cabinets are built of 18mm Baltic birch with battens on all edges. I will do as you suggest.

The sound I am hearing is not a buzz that would suggest a bad joint, and the rap test gives a tone well above 100Hz. In particular, there is no change in the SPL of the offending notes, just a change in timbre. But, I will do as you suggest.

Thanks,
Bob

Bob,

If you identify the problem, acoustic or mechanical, please let me know so I can see if it is something that could be added into an upgraded H frame simulation model.

Martin

[Bob Brines]

Re: Is H-frame sub using GW-1858 "fast" enough for Maggies?

Bob,

If you identify the problem, acoustic or mechanical, please let me know so I can see if it is something that could be added into an upgraded H frame simulation model.

Martin

I'm going to play with it tomorrw.

Bob

[bbtk]

Re: Is H-frame sub using GW-1858 "fast" enough for Maggies?

It's a really hollow sound over a narrow band width. It's not very noticeable in rock music, but I identified it loud and clear is a piece of Vivaldi. Three notes in the 'cellos just sounded horrible. Knowing the piece well, I knew exactly what frequencies to look at.

Bob

That sounds like it could be a phase issue to me, based on my limited knowledge.

I once built a test baffle of an H-frame subwoofer using 4 15" Pyle Pro woofers, after a discussion in diyaudio. I could not get a good integration with my Linkwitz Orions with the limited testing I did. I also called the bass "slow." The poor build quality of the drivers and the problems integrating made me send the drivers back. I tried searching for that thread, but couldn't find it. Here's another one I remember reading that is pertinent to the issue of "fast" or "slow" bass.

http://www.diyaudio.com/forums/subwoofers/166817-fast-sub-anyone-2.html

[Bob Brines]

Re: Is H-frame sub using GW-1858 "fast" enough for Maggies?

I spent all afternoon trying to discover the problem with my H-frames. Yes, the problem is not a resonance. I ran a THD sweep to see if anything popped out. To my horror, the miniDSP is injecting huge amounts of 3rd order distortion into the signal. I don't know if I just got a bad item or it is endemic in the miniDSP. Attached are the traces. The first plot is the GW1858 driven directly through a DAC. The second is the GW-1858 driven through the miniDSP with everything set to bypass. The third is the Alpair 7.3 direct. The fourth isthe 7.3 driven through the miniDSP. WOW! Just for grins, the fifth plot is the GW-1858 FR and the sixth the A7.3 in the small TL I am using for this pairing.

Color cod for the THD plots: 1=white, 2=white, 3=red, 4=blue, 5=green, 6=yellow.

As a backup, I setup a crossover and a graphic EQ in Foobar2000. The results are promising, but not quite there. From the plots at least, the GW-1858 is good up to ~500Hz. I would up with the low-pass at 150Hz and the high-pass at 200. I hope I can get this worked out by LSAF.At the moment, the W8-1772 MLTL sounds better on all counts except slam on rock.

Bob

[Bob Brines]

Re: Is H-frame sub using GW-1858 "fast" enough for Maggies?

Just for grins, the first plot is the GW-1858 FR and the second the A7.3 in the small TL I am using for this pairing.

Bob

[martin]

Re: Is H-frame sub using GW-1858 "fast" enough for Maggies?

Thanks for the update Bob.

For me this is a nice result, the H frame measurements seem to correlated well with the MathCad calculations.

[r-carpenter]

Re: Is H-frame sub using GW-1858 "fast" enough for Maggies?

Bob, are you using S&L software for all your needs? How is it? Do you like acoustic measurement suite?

[Pete Schumacher]

Re: Is H-frame sub using GW-1858 "fast" enough for Maggies?

I spent all afternoon trying to discover the problem with my H-frames. Yes, the problem is not a resonance. I ran a THD sweep to see if anything popped out. To my horror, the miniDSP is injecting huge amounts of 3rd order distortion into the signal. I don't know if I just got a bad item or it is endemic in the miniDSP. Attached are the traces. The first plot is the GW1858 driven directly through a DAC. The second is the GW-1858 driven through the miniDSP with everything set to bypass. The third is the Alpair 7.3 direct. The fourth isthe 7.3 driven through the miniDSP. WOW! Just for grins, the fifth plot is the GW-1858 FR and the sixth the A7.3 in the small TL I am using for this pairing.

Color cod for the THD plots: 1=white, 2=white, 3=red, 4=blue, 5=green, 6=yellow.

As a backup, I setup a crossover and a graphic EQ in Foobar2000. The results are promising, but not quite there. From the plots at least, the GW-1858 is good up to ~500Hz. I would up with the low-pass at 150Hz and the high-pass at 200. I hope I can get this worked out by LSAF.At the moment, the W8-1772 MLTL sounds better on all counts except slam on rock.

Bob

You've hit on something that may explain why DoubleTap and I dumped the miniDSP in favor of a line level analog filter for bass duties.

[DoubleTap]

Re: Is H-frame sub using GW-1858 "fast" enough for Maggies?

Wow, interesting Bob! I'll hook my MiniDSP up and see what I get. Right now I know it sounds like hammered sh*t, just don't know why.

[Bob Brines]

Re: Is H-frame sub using GW-1858 "fast" enough for Maggies?

Bob, are you using S&L software for all your needs? How is it? Do you like acoustic measurement suite?

Yes, I use WTPro for everything. I suffered through Speaker Workshop and SoundEasy (which I haven't used in ~5 years) and each measuring session started out with an hour or so getting the jigs right. WTPro just works. Plug it in and measure. Period. My only gripe is that pretty-printing can be a pain. I still have a copy of SW to play with presentation. If I get off the dime, I could do this in MathCAD or even Excel, but I haven't cared enough yet.

Bob