Full range >98dB SPL drivers for 45 tube

[planet10]

Sachiko cabinet design has been updated and re-named Kirishima and is supposed to be significantly improved

I don’t know that it is that much… maybe applies if you are talking about Vulcan.

I have friends with FE206eSR and they are good in even the factory design (not the best, and certainly a pig when it comes to eating up material)

dave

 

[BHD]

In all honesty if I was looking to do a double horn right now I'd be doing the Vulcan but I'm probably going to go with the Dallas II as I'm going to be moving them down into the basement which is a smaller room that is not likely to suit big horns. My lovely Yorkshire bride is a bit of a basshead and so I'm going to either do Elsinores upstairs or some kind of crazy huge BIB.

Dave, have you played with the EV 12TRXB or the SP12B?

 

[planet10]

I recently gave away a set of SP12B. The guy i gave them to, reconed them, put them on an OB and rather likes them.

dave

 

[BHD]

If my experience with the 12TRXB in the "JE Labs" open baffle is any indication I'd have to say I agree with your friend's assessment of the drivers. Good on you for sharing with your friend. One of my 12TRXB's had a buzzy cone so I've found a pair of SP12B's on the 'bay. What tweeter would you recommend (if you have any in mind)?

 

[ripson]

I recently put a pair of Electro-Voice 12TRXB drivers in the "JE Labs" open baffle and was absolutely shocked by how good they sounded.

Thank you for your inputs. BTW not so long time ago I've tried my chances on online auctions with these drivers. Do you know if there is any difference in T/S between the 12TRXB/SP12B drivers with bright basket and 4 arms and the brown one?

 

[planet10]

No opinion there. The local who i gave them to is not using a tweeter.

Adding a tweeter to a big wide range is fraught with issues (any XO above a quarter wavelength of the driver centre-to-centre multiples the issues with XOs). I much prefer adding woofer(s) to a small FR.

dave

 

[BHD]

Well, thanks for the reply anyway, I may measure the response and try a Fostex supertweeter if the response of the SP12B goes high enough, don't know what to do if not but I'm sure I'll come up with something.

 

[KaffiMann]

View attachment 672081

Never heard this driver, but the published FR isn't that scary IMO. The on and off-axis plots mirror themselves to some extent, which should make for a good power response in-room, with the caveat that I'm not sure what angle the blue trace was taken at. Perhaps the ~5kHz-8kHz area will be a bit hotter.

Blue trace is 45 degrees off axis. Very good for a 15" FR methinks. It sounds great.
Quite common for big FR's to have a rising top end.

 

[Bigun]

No opinion there. The local who i gave them to is not using a tweeter.

Adding a tweeter to a big wide range is fraught with issues (any XO above a quarter wavelength of the driver centre-to-centre multiples the issues with XOs). I much prefer adding woofer(s) to a small FR.

dave

You could place your super-tweeter somewhat on top of your wide-bander. This will put the acoustic centres much closer together, trading-off other performance attributes.

Hammer Dynamics Super 12 Loudspeaker Kit

 

[Scottmoose]

Unfortunately it also brings its own problems from reflections & interactions, and the Hammer was, by several accounts, a good example of that, notwithstanding its other merits. Speaking as somebody who designs & uses both wideband & multiway speakers, given a choice I'm with Dave -I'd rather partner a dedicated woofer with a quality mid-tweet than try to get a small tweeter integrated with a large bass-mid.

 

[Bigun]

I agree that the tradoffs are better that way, but for folk who want 97dB or more (claimed for the Hammer dynamics) there aren't too many mid-tweets available unless going horn.

 

[Scottmoose]

Quite, which is why IMO they'd be better off biting the bullet & doing just that (as in a quality coax or dedicated HE woofers with horn loaded compression mid-tweet) if efficiency is the big goal. Certain exceptions, but as a rule it tends to be a good one.

 

[planet10]

who want 97dB or more (claimed for the Hammer dynamics)

Claimed but optimistic. A local built a set of these, he spent a lot of money trying to get them to sound good, but eventually he sold off the parts and the cabinets went into our big fall bonfire.

dave

 

[phivates]

Ah yes the failed experiment bonfire. Too bad the town I live in doesn't allow such festivities.

 

[Bigun]

Quite, which is why IMO they'd be better off biting the bullet & doing just that (as in a quality coax or dedicated HE woofers with horn loaded compression mid-tweet) if efficiency is the big goal. Certain exceptions, but as a rule it tends to be a good one.

what makes a quality coax a 'quality coax' ?

 

[planet10]

It is quality if it sounds good, consistent, and good build quality..

dave

 

[Bigun]

Is that an answer or additional criteria in support of my question?

 

[Scottmoose]

A reasonable answer. A quality driver of any kind should be well made, with consistent production QC & have a balance of properties that produces what somebody would call for a reasonable set of criteria 'good sound quality'.

A non exhaustive set of expansions would be -well-designed main cone for the given material with carefully selected profile & optimised to a target response or set of properties. Same for the central compression mid-tweet with a quality horn design as appropriate. Quality motor providing low distortion, with proper cooling to the magnet, VC etc. If supplied, a crossover that is well-adapted to the driver frequency responses & distortion performance, that produces a response that is either linear or tracks a desired curve, made using decent quality components. Support components e.g. connections that allow easy, effective & reliable signal transfer. Those are a few (far from all); basically similar to other drive units, suitably modified for a given type.

 

[Bigun]

You got me interested.

Here's a quote cross-referenced from another thread:

Interesting thread....

After working with Altec 605A, 604E & 8K's, P.Audio BM18CX38, Selenium 15CO1P, Vifa A20CN-21-04 and a host of other coax designs, I wish to make the following observations.

I have utilized (experimented with) sealed, ported and OB configurations with all of the above. And produced quite a number of traditional multi-way (individual drivers vertically mounted) systems to boot.

As has been pointed out, all designs have their respective limitations.

Coax drivers, in general, seem to be considered suspect, odd if you will. They rarely sell well, save the Altec and Tannoy duplexes. Hifi versions over, say, 8" are rare. Ceiling and pro sound reinforcement have been the primary markets for the majority of coax designs, save Altec and Tannoy high output, near field monitors. (OK, Stephens, Jensen and others too!)

I think the real issue revolves around crossover, as usual. Most Pro crossovers supplied with or recommended for coax drivers are geared around max power handling, projection and very limited bass extension. This makes perfect sense in a sound reinforcement application.

In a residential Hifi application, output capacity is way down on the list of priorities. Bass extension, LF & HF near field integration and near field power response are primary. Most larger coax drivers can be molded and shaped to work well in a hifi role with the proper cabinet (or open baffle) with a correct crossover. Not having to deal with vertical separation, and having a fairly limited horizontal separation are real pluses. However, integrating a large diameter, high mass woofer and a compression driver with a very short horn (or large wave guide woofer cone) is not easy. The two drivers have very different harmonic structures and the designer has to utilize the woofer into the upper mid range. Even with the P.Audio BM18 which provides a 16" wave guide (cone), the lowest you can work the HF driver is around 800 Hz. And in the world of traditional hifi multi-way systems, it is considered foolish to run an 18" much above 250 Hz.

I have found the best of the coax designs offer woofers that work well, as in flat in the frequency domain up to at least 2K. Yes they will beam, but some of that is offset by the lower end of the HF drivers band pass. Which gets to the nut of things, what you normally have is a woofer that can reach up fairly high with a modest rising response, but you need to mate it with an HF section that has a sharp cut off on the low end of its band pass. And there are the inherent efficiency and dispersion profile differences to deal with. Effective crossover solutions look very odd as compared to a typical (vertically separated driver array) two way. Oh yeah, the crossover frequency is in the the upper mid range, a sensitive area in the audio spectrum containing a lot of content.

Some of the best commentary and work concerning large coax crossovers intended for hifi applications is offered by Jeff Markwart in his excellent Altec duplex site here: Jeff Markwart's Corner - Phase Corrected Crossovers

One thing that stands out with my coax work is the crossover has to be spot on. In most cases you can get away with a less than perfect crossover solution with traditional vertical driver layouts. There is a bit of forgiveness if you will. There is usually a bit of usable over lap with basic roll offs similar enough in shape you can blend a bit. Yes, no substitute for getting it as right as you can, but, you do get to a point of diminishing returns. Not so with the coax. Either it's right on, or it's disappointing. REAL disappointing!! Ragged, edgy, not at all coherent. Part of this I believe is the parts of the spectrum that are so right on point out the short coming in the crossover region.

However, the more practical question is which currently available coaxial drivers would be recommended to the DIY'er around here for use with a low power SET ? - the GPA 604 is the only one I've seen mentioned a lot.

 

[planet10]

A 10” Tannoy would be my pick, but consider this… in a WAW with driver can†res within a quarter wavelength at the XO frequencies you essentially have co-incident drivers (co-axials would be a subset of this), and with this criterion a large number of issues with the XO go away.

dave