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In Reply to: RE: General speaker design characteristics for a 2A3 amp posted by saki70 on April 11, 2017 at 11:59:39
2A3 amp: 100k volume pot input from source, two stages direct coupled, JJ 2A3-40 into 3k ohm output transformer, 3W output
High efficiency speakers: >100dB efficiency; 16 ohm load, 15" woofer.
Thank you for your response .
Do you think that an average 2A3 amp has enough umph to push a 15" bass speaker ? Or would it require a larger than average PS ? I am not real familiar with size , as you listed on your amp suggestion , for
transformer capacity .
Any other speaker suggestions ?
It's not just the 15 inch driver, it's also the cabinetry engineering, system
wiring, and amplifier characteristics that count.
The same 15' driver could be starving for power on 100 watts from one amp, and have ample power with another that is one watt.
Speaker cabinet engineering and wiring (crossovers included) is just
like that also.
THE most important consideration of all of this is cabinet internal
volume. Do your math. (see Quarter Wave theory, and consult other
If you make a cabinet even one cubic foot too small, better
install Car-Audio drivers with 1000 watt solid state amps..
Outstanding audio comes from LARGE, exactly engineered enclosures.
tube wrangler ;
I hear ya...but I do have a WAF to deal with here !
So far I've got 100db efficiency , 16 ohms and a 15" woofer .
Would a somewhat smaller woofer , say 10" or 12" , suffice in a near field situation of @ 6' or 7' ?
Keep'em coming please .
WAF: A guy just called me over this.
He recommended that I build the same speakers
in glossy piano-black built in exactly the same sizes..
He claims that he did this, and his wife
liked the piano-black model.
Apparently, it went something like this:
"See Henry how much better it is when you listen
to me and make them smaller?"
They were the exact same sizes!
I've been mulling over building a smaller speaker
because of WAF for years.
But, I haven't done it because I've yet to hear a
small speaker system that performs musically in the
things that I enjoy-- point-source, wideband micro
and macro dynamics.
The other problem is engaging the listening room.
This requires moving lots of air at low distortion levels.
You can use subwoofers and get air moving at the low-end
but is this really compatible with the rest of the system?
I don't like it-- but YMMV. I also think that a good
woofer sounds great all the way up to 1700HZ or so...
There are plenty of speakers that sound and measure
well themselves, but will not turn the listening
room into the event you're listening to. You are
aware that you're listening to a speaker.
Sometimes we assume that the room is engaged when
imaging, field depth, and soundstage vertical &
horizontal are all OK.
Where is the power, glory, and dynamics to go
I don't like the sound of 12" woofers at all.
There are some 6 1/2 and 8 inchers that sound GOOD,
and one can find these in many of those "sounds
better than it should for it's size" models.
You'll find multiples of these smaller units in
some expensive speakers that "do it all". Measurement-wise?
Certainly. Getting the ROOM to play music well?
Well, not so much...........
It's like saying "my little auto has more power
than I expected". And that's fine. Just don't compare
it to a FORD GT. (did Ford really build 500 of those?).
I don't know, but for a smaller speaker, all I can
think of is use the 15" Altec-style woofers in enclosures
that are 1/2 the cubic foot volume of ideal Querter-Wave
This cuts-off the extreme low-end but still leaves you
with a speaker that you can really love over the long-haul.
15" woofers are interesting. JBL made a latest model that
is rated at 101db/watt. GPA has one also, more along Altec
design lines. Their "604" series is really outstanding when
used properly. It's been pointed out to me that this 15"
woofer has a rather large hole in its middle to mount the
tweeter/midrange short-horn, and therefore, has less woofer
surface area than the single unit woofers, and also might have
horn-in-the-middle colorations due to the horn being placed
where bass energy can bounce off of the horn, and the horn is
too short (front-to-back) to compete with the best
All true, but the thing PERFORMS musically. No matter what
you like to play. It's just outstanding in so many ways.
Other brands of 15" woofers are out there, and I've been able
to compare some of those.
In general, I found that 15" woofers that had efficiency
ratings of 98, 99, or 100db/watt ratings just can't compete
with the Altec, JBL and GPA 101db models. There's just no
contest at all when it comes to listening to them.
That extra db or two wasn't gotten easily, and the results
are certainly audibly superior.
Sounds interesting , thank you for the info .
By the way , are those prices concurrent ? Those ads remind me of the old turn-of-the-century catalogs that my grandfather gave me . You know , the ones with $10 stoves and such !
tube wrangler ;
You do have a habit of making very convincing arguments favoring your choices !
I wonder how close one could get with a flat pack and kit using a smaller bass driver ? All of this , to begin with , is an experiment to see what
this type of arraignment is all about . Not necessarily the final product .
But please , keep'em coming . I am learning a lot and that ain't a bad thing !
Thank you .
sorry, I thought that would be obvious.
Link below FYI (great resource for info, as is the sister site www.radioshackcatalogs.com )
all the best,
Again, high sensitivity drivers are required, and, as others have pointed out, appropriate enclosures/baffling will provide "best results".
I'd suggest giving consideration to 12" coaxials. Personal favorites are the vintage Electrovoice "Wolverine" (their budget line) LT12. This is a 12" woofer (essentially the EV LS12) with a coaxial "whizzer" cone for midrange and a coaxially mounted EV T-35B compression driver/diffraction horn tweeter.
Nice sounding, beautifully made, and not expensive even on eBAY -- not terribly common, but there's usually a pair on there.
These can be put into large-ish vented boxes or used on "open baffles", perhaps with some subwoofer support for bass.
The other EV 12" coaxes (12TRXB and 12TRX) are pretty good, too -- but I really like the LT12 and they're far cheaper (i.e., represent, to my tastes, much better value).
(the mismatched cabinets in front of the Duplexes contain a pair of LT12s in this photo)
all the best,
As he said, 100-ish dB (per watt @ 1 meter) woofers (e.g., Altec 416 family members, or the Altec Duplexes I mentioned).
all the best,
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