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Old 29th June 2004, 01:02 PM   #1
Eisbaer is offline Eisbaer  Germany
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Join Date: Jun 2004
Location: In front of my PC
Default Me wants to build a bass box

Hello alltogether!

I’m a complete Newbie (excuse my somehow bad English and my perhaps stupid questions), but I want to built my own bass box (only a box for a stack - no amp!) for my e-bass… (stupid I guess… )
Already downloaded WinISD Version 0.44 (don’t like the WinISD Pro 0.50 Alphas – too many bugs in there) and chose some speakers, too. Played a bit around with this one and ended up with questions in mind, ‘cuz the “default” box WinISD calculates isn’t exactly what I’m looking for….

Okay, the data what I want to build (and questions I’d like to ask) :
- 1x10” + 1x15” bass reflex box (each speaker in an
own cell)
- Eminence Gamma 10 for mids + highs
- Eminence Beta15/Gamma15/Kappa15 (not sure
which makes it in my final design ‘cuz this topic is
one where I have some questions left) for basses
(I want to get a low b fired out off the box as best
as possible) and deep mids
- I’d like to tune my box (the 15”) that way down,
that its possible to have 35Hz at –3db.
o Me doesn’t get this done without getting huge
dimensions…
o I downloaded the spec sheets off the homepage
(already changed the Thiele-Small parameters in
WinISD’s database for the relevant models) of the
manufacturer and everytime I blow up the
recommended size of the box when I try (with
every speaker. Even tried with Pro and LF models
but happened too)… -> so ->
o Is it even possible (without damaging the
drivers, getting a good response of the box and
without getting muddy or distorted sounds) to get
these speakers (and which model of the above
ones especially likes that?) down to that (a “how”
would be nice)? Or should I look for other models
and manufacturers? (advices/recommendations
appreciated – they should be built for PA and
electric instruments (e-bass) just to have that in
mind)
o Some other questions:
- May I ignore the recommended size specs of the
speakers (and to which extent may I ignore that)?
- Above which value in ms does the delay start to
disturb the experience of the sound – when does
it get annoying?
- Must be the Tuning frequency of a bass reflex box be identical
with the –3db frequency?
- To which extend is it possible to “tune down”
(the Tuning freq.) a box or is this unrelated to the
drivers? (I mean WinISD gives me a value : 48,74
in a 104,6l box for a Kappa 15 speaker – so, how
low can I push it without getting crappy sound?)
- Yeah, I guess the most questions can be
answered by a good book, but hell – I don’t have
the cash left for that. Sorry, guys

I guess that’s quite a bunch
But I would really appreciate some help ("forget it and buy a box" isn't a option right now)
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Old 29th June 2004, 01:13 PM   #2
sreten is offline sreten  United Kingdom
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Location: Brighton UK
Tuning frequency for a reflex for low B should be ~ 30Hz.

You can safely tune any alignment given by WinISD
with a higher port frequency down to 30Hz.

Generally the low port tuning doesn't help frequency
response that much but does improve power handling
around the port frequency.

Given the cabinet is going to be big and you'll have to
lug it around compromise hits home with a vengeance.

You''ll quickly realise no-one uses hifi type extended
alignments with these drivers, the boxes are far too big.

sreten.
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Old 29th June 2004, 01:15 PM   #3
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Quote:
To which extend is it possible to “tune down” (the Tuning freq.) a box or is this unrelated to the drivers?
Tune above Fs
Tune to a region which gives a flat or overdamped response
Tune to a region which helps power handling

Quote:
Above which value in ms does the delay start to disturb the experience of the sound – when does it get annoying?
THe winisd manual quotes 5% speed of sound ~18m/s i think..


Efficient,small,low frequency,chose 2

an F3 near 40hz is well good for bass.
4 string extends to ~42hz..
6string extends to 32hz..
Try Eminence drivers ...often small box with a full low end for guitar bass.

35hz F3,will have to be large.Probably 40hz F3 is good enough/

For example my 2226JBL requires 175Litres and 33hz tuning,the result is overdamped and quality...but the 35hz area is several db reduced...its more optimal to have a 45hz F3 and small box :-)

Make sure to read the winisd helpfile.

ANd finally before finalising your decision,compare this program with another to be sure .
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Old 29th June 2004, 05:50 PM   #4
Eisbaer is offline Eisbaer  Germany
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Join Date: Jun 2004
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Thanks guys. Finally I was able to make a "useable" design but one question:
How to improve power handling for my project (for some "fine" tuning)? Sreten says tuning freq. and it did, but what else is possible (except dimensions) and additional or other drivers?

@mikee: I read the manual but it didn't cover the info I was looking for Or at least I didn't find 'em...
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Old 29th June 2004, 06:09 PM   #5
sreten is offline sreten  United Kingdom
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For "power handling" you need to trade off driver efficiency
versus Xmax of the driver. Simply choosing a lower efficiency
driver will improve "power handling", the real issue is max
SPL capability in a reasonable cabinet size and driving power.

sreten.
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Old 29th June 2004, 09:14 PM   #6
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Two points. First, forget about F3 at 35 Hz because you just don't need it. The maximum output of the electric bass takes place in the second harmonics, not the fundamentals, and a speaker capable of running to an F3 of less than 60 Hz is just not required. As an example an Ampeg SVT F3 is 60 Hz.

Second, don't duplicate so much range with your drivers. The fifteen is quite happy up to at least 800 Hz, the ten is good down to 100 Hz- that's a lot of overlap. Put more money into the 15 where you need it and go with an 8 for the high end. A Gamma 15 and Beta 8 makes a lot more sense.
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Old 30th June 2004, 11:40 AM   #7
Eisbaer is offline Eisbaer  Germany
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Join Date: Jun 2004
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THX sreten for your "real issue"-explanation. Just what I wanted

Okay, already forgot the F3 at 35hz - now its around 45hz for the Gamma 15 cell...

I thought I could handle this huge overlap with a freq.-switch (freestyle translation for German Frequenzweiche - but I guess you guys get the picture ).... 'cuz a 10 has more power in mids than an 8.... and I don't like highs that much.... and I don't need them much...so I thought the 10 would handle that in a sufficient way.
That should be a bass box designed for Death Metal, so no need for highs (but for basses and (deep) mids ) - at least not in my sound.....
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Old 30th June 2004, 01:30 PM   #8
sreten is offline sreten  United Kingdom
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TBH IMO a Gamma 15 will not benefit much at all with an added
10", and will soak up amplifier juice without giving a lot in return.

The Gamma 10 will not work well with the Gamma 15 due to
the difference in sensitivities and will half the cabinet impedance,
some capacitive filtering is also needed to prevent bass overload.

The Alpha 8MR is a much better idea and as this would use a
1st order filter set at ~ 1KHz would not effect cabinet impedance.

A plain 2x15 or 4x12 is possibly a much better idea IMO.

sreten.
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Old 30th June 2004, 04:20 PM   #9
Eisbaer is offline Eisbaer  Germany
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Oh man.....

Building boxes is more complex then I thought....
As a total noob I guess my idea is just a plain overkill (would be my first box though...), cuz it seems impossible to build that without knowing the more complex tricks of PA systems....(filtering and stuff)
...
So I better get back to some standards I guess (at first - muhaha I WILL RETURN ).... but nonetheless thx guys for helping and the advices (and so you saved my money and me from bitter mistakes)
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