Heathit AS 101: Help with tuning cabinets for deeper bass

[mpent]

Hi,

I acquired a pair of 101s a couple weeks ago. I have since replaced the caps and L Pads (one of which was fried). My next goal is to see what I can do to increase the lower frequency response. I am currently using a 10 inch sub to fill out the low end. I really a enjoy a thud to my low end listening and when I remove the sub I definitely find myself missing it. I have been reading what is out there on the forums (including this one) and trying to figure out how I can tune these cabinets for deeper bass. That being said, I am wondering if part of my issue is that I am not used to 2-way speakers. For the longest time I have had Klipsch Fortes in my main system, intermittently adding a subwoofer when I desired a deeper bass response. With the 101's I just feel that the low end is so absent...no thud. Not sure if the problem is with my expectations or if the frequency can be improved otherwise? I know this has been already stated in the forum but I am wondering if someone could be so kind as to break down a recommendation of tuning the cabinets for deeper bass. Currently, the horns have the stock recommended insulation on both sides as indicated in the assembly manual. That is it. Am I removing that insulation and replacing it with wood for the tuning experimentation or am I trying to tune the port below the horn? Thank you for any assistance you can provide...

Regards,

Michael

[Old Guy]

About the only thing to do is build a bigger box. You can try entering the internal dimensions in a design program and playing with porting. But I doubt it....

A sub is likely the best option.

[fpitas]

You might try Acousta-Stuf as a fill. It doesn't absorb low frequencies as much as fiberglass, so there's an opportunity to make the cabinet "look bigger" without degrading the box Q too much. Filling with about 1lb/cu ft should make the box seem about 25% larger in volume.

Acousta-Stuf:

http://www.parts-express.com/pe/show...number=260-330

It's not cheap, but I've stuffed ported cabinets with it with excellent results. I suggest you bring all your parameters (box volume, TS parameters etc) into WinISD and play with the port length to get the best bass extension. I've modeled the fill by setting the box Q low, about 3, and got good agreement between the model and reality.

[mpent]

So replace all existing fiberglass fill with Acousta? So the lacking low frequency is pretty standard with this speaker? I ask because I am new to DIY audio and part of me is just making sure that these speakers are sounding as they should. After replacing caps and L pads I definitely heard a sonic improvement with the sound stage and dynamics but it did not do anything for the low end output other then sounding better integrated overall.

[fpitas]

If an L-pad was fried, have you checked that the woofers are still Altec?

[GM]

Greets!

You can’t really extend the LF for more ‘thud’, only reduce its mid-bass ‘punch’ with a lower tuning and since the vent is nothing but a large slot the horn protrudes from, there’s no convenient way to block it off and install a tube vent without dismantling the baffle and I presume the grill assembly, so about your only easy/cheap option is to damp [stuff] it even more than it already is.

Removing most of the damping to more like the way Altec damped the Valencia [its ~twin] will yield a bit more mid-bass presence, which is what most of the ‘bass’ is in a prosound app, but then the deep bass will be even more rolled off, though it may allow a lower ‘sub’ XO point to be used.

Bottom line, for more bass gain BW it needs a significantly larger cab tuned lower. That, or use EQ to reshape its frequency response with a 3-6 dB lower system efficiency as the trade-off depending on how low you want to go and how much the room affects it.

If you want it to sound as it was intended though, then the way to go is driving it with a period correct tube system that includes tone controls. This will reshape its response somewhat due to the amp’s high output impedance, flattening the response out somewhat, making both the LF and HF sound a bit more extended and the tone controls will typically have enough adjustability to flatten them out in room to as low as any vinyl recordings I’m aware of.

GM

[mpent]

Thank you everyone for your responses and for helping me wrap my head around this. Fpitas, yes the woofers are still Altec. Sorry but what would be the correlation of a fried l pad and whether the woofer was still altec?

I'm thinking that the problem is with my expectations for deeper bass and not the speaker itself which I'm glad to hear in the sense that it is sounding as it was intended to sound. Thanks again.

Michael

[fpitas]

Michael,

Often something like a fried L-pad means the speaker has been abused, and the woofers may have been blown, too. Altecs are expensive, so sometimes people replace them with another (cheaper) brand. I'm glad your woofers are still Altec.

[alancohen]

So this brings up an interesting question. How do those all-in-one little subwoofer boxes get to the specs they represent? I think even Altec made a self-contained subwoofer/amp. I have an old KLH subwoofer with a 10" driver and it definately goes lower than my A6s with (4) 16s.

Along the same lines, how do smallish full-range loudspeaker systems get to 35Hz? Are they sacrificing that wonderful Altec mid-bass, and/or effeciency, in exchange for a pretty FR graph?

[cradeldorf]

Have you tried reversing the woofer wires? Just wondering because my 101's used to shake the house off the foundation. Although Mine had 604's in them. still they should knock stuff off shelves on their own. Mine had ports the size of the horn hole.