Help-2 FR's per side w/one OB other enclosed

[FrankK]

I find that the only fault with my full range on open baffles is a leanness in the midbass. I have tried absolutely everything electronic wise but it is still there.

I am thinking this is just something that is inherent with OB speakers and so I hope to build another speaker on OB with two identical 8-12" wide band (will augment with woofer under 100-150hz and tweeter over 10k) drivers per side.
One will be running open baffle with another driver under it enclosed in some manner to capture that warmth and musicality that is lacking in my set up.

Any negatives to this idea?

Also I was thinking one option might be to find two 16 ohm drivers to run together at 8 ohms. I haven't been able to settle on the drivers to go with as most I have considered either have a rising mid or drop off in the lower mids. I even thought of some vintage drivers but whenever I read about them the general description is that they lack openness and detail (aside from the rare and expensive Altec 755A). Any help here too would be appreciated. One more priority is I have a large basement so they should be able to play at high SPL levels.

Thanks in advance.

[Scottmoose]

Running a pair of 12in drivers wideband on the same baffle is asking for trouble; a couple of small drivers you can usually get away with, but not when it gets to this sort of size; lobing is almost certain to be an issue.

Re vintage drivers, neither 'openness' nor 'detail' actually mean a great deal other than giving some indications of the distortion & dispersion characteristics. Some older units are still as good (or better than) many current drivers, but there was plenty of rubbish around too which is still flogged for inflated prices. Your main problem would be to find 4 identical units, closely matched in spec. That's hard enough to do with brand-new drivers, let alone 15th hand, 5 decade old units picked up of ePay (or whereever). You'd have to measure them to find out exactly what they're up to as well.

[FrankK]

Okay so lobing would be one negative.

At the same time you may be familiar with Bastanis speakers and they have now gone to a two driver per side arrangement on their Atlas (formerly Prometheus) and from everything that has been written there seems to be no negative consequences other than more space is needed around the speaker.

I hear you about vintage drivers and maybe I should consider newer drivers(also need around 100db for my 8 watt SET amp).

[Scottmoose]

Yes, I know the Bastanis. Doesn't necessarily mean I think they're up to much, but I know them.

If that's the kind of efficiency you need, I'd be more inclined to start looking toward a couple of 15in HE woofers crossed at ~500Hz to compression mids / HF.

[gvimhoof]

Originally Posted by scottmoose

yes, i know the bastanis. Doesn't necessarily mean i think they're up to much, but i know them.

if that's the kind of efficiency you need, i'd be more inclined to start looking toward a couple of 15in he woofers crossed at ~500hz to compression mids / hf.

woof!

[FrankK]

Correction.

If I do find 16ohm speakers and then wire them in parallel I suppose the efficiency could be around 95db (not 100db as mentioned earlier)with as to begin with as theoretically it should give me around 98db which is what I have now with my single OB speaker and is fine with my current SET amp.

[InclinedPlane]

This might sound odd, but
I solved my OB midbass problem using the Jensen C15k 15" bass guitar speaker. It is 100db in the midbass area and the Q is just shy of .9. The 1mm xmax is absolutely a non-issue at aggressive volume levels also.

As a fringe benefit, it produces the most remarkably accurate midbass I've ever heard. No, I don't work for them.

[FrankK]

The rising midrange as shown on the Jensen chart for the c15k has too much of a rising mid for my liking.

C15K

I think the point of the post was a little lost when I mentioned driver selection as well. My main curiosity is what would be the effect of using two drivers with one being ob and the other closely below it but being boxed (not sure sealed, IB,or....?) I suppose sort of like Nola/Alon or the Gr Research speakers but with two similar drivers and being larger diameter than what they use for their mids. I am hoping to combine the openness and ease of ob with the full mid sound of an enclosed speaker.

[InclinedPlane]

Oh, I thought your concern was a 'leanness' in your midbass (middle-bass), not midrange. I take midbass to be in the neighborhood of 100-300hz or so and the guitar speaker is around 100db in that area and in fact output falls toward 400hz. So I'm not following you well in your most recent post.

[planet10]

Bass = 20-40 Hz
MidBass = 40-80 Hz
Upper Bass = 80-160 Hz.

Upper Treble = 10-20k
Mid Trable = 5-10k
Lower Treble = 2.5-5k

The 4 octaves left are the midrange.

dave