Hawthorne OBs

[steve s]

Must Agree With Paul about the baffle size, i have found moving next to a side wall makes a big difference to to the bass output.. but that depends on what you listen to, as only a small amount of what i listen to has any deep bass..

i played around with extra boards taped and clamped to the main baffle to get a reasonble response.. then got the mk 2 a little wrong..

steve

[Scottmoose]

It's deliberate guys. The SI drivers have a Qt of 0.91, & they're intended to work best on relatively narrow baffles. A wider baffle will have the effect of boosting the response over the ~nominal, a bit like engineering an artificial peak into the LF of box speakers. They have matching woofers they can be partnered with too.

Why coaxial? Point source from the forward radiation is part of it. That's also a 15in cone being asked to do the job of a mid-bass driver. They can do it, but it probably wouldn't do the polar response many favours if XO'd to a tweeter mounted separately.

[Paul Barker]

Yes I see what is happening. The ability of the 15in cone to manage with everything up to a tweeter cross over point is pushing it into guy in the pub with a pair of boxes on stands with a 12" or 15" boom banger and a horn tweeter category.

I am presently trying the Axiette in the stead of the Nice little Fostex fe108eΣ

which has pros and cons, it's nice to get the more linear distribution of magnetisation which alnico is renowned for (Bruce Edgar takes a morning to explain this benefit in full), but the cone of Axiettes though revolutionary in it's day can't be quite perfect as there is a certain nastyness with some music. They do however reproduce real instruments in a really faithful manor, so perhaps the nasties I hear exist, they are geting the blaim for it.

Hopefully I should be able to demonstrate what I am finding to date, and compare it to the Fostex version, which now sounds coloured by a very strong sonic signiature of the drivers, yet is extremely pleasing. Most people like the sound of this driver, it's now been revealed as adding a great deal of it's own tone in my experience, not a bad tone whatsoever. It might yet be the better sound of the two drivers.

As for the bass helper the Alnico 15" Jensen is quite an improvement, but it may not be as good as Nick's we shall find out soon shan't we? I was fortunate to only pay £75 delivered for the first one but they don't grow on trees and new price is a little heavy so I might go with a mismatch until another half price one turns up. I was lucky to spot that this one was badly listed as a 12" driver.

[Richard Higgins]

Hi Paul
My impression of the OB bass compared to the Impulses is that it is not as strong, but it is more detailed.
I use them about a foot in front of the Impulses (the black above and behind the RH speaker in the photo) which means they are about 30 inches from the wall, but compromised by the closeness of the Impulses.
As Scott says and according to the Hawthorne BB, the speaker is designed for a small, flat, baffle, and making a large, or deep sided baffle leads to one note bass. I tried 6 inch sides but did not notice any change, so went back to 3 inch sides.
I wanted the tweeter at ear level. Any lower and they loose too much treble due to the closeness to the ends of settees.
The tweeter appears to be an Eminence ASD1001 which features a diamond titanium diaphragm and costs about £18. It has a 1 3/8 x 18 thread on its nose which is screwed directly into the centre of the main magnet assembly. Darrel Hawthorne writes that the more expensive Eminence tweeters handle more power, but do not sound better.
For greater bass Hawthorne sell an additional 15 inch speaker called the Augie. This is reviewed in a second article on TNT Audio.
http://www.tnt-audio.com/casse/ha_si_part2_e.html
I still need to use them more, to get them fully run in, complete the baffles, add spikes to the bases and make them look presentable.
So far their performance is not perfect, but for the cost, a good introduction into OBs, and worth further development.

Regards Richard Higgins

[steve s]

Thanks scott, so there not designed to go low is that right...
iam sure they are not missing much at the bottom still..
but lows on o'b is still a physical thing..

still don't quite get the point though.. i sort of would imagine a loss of upper bass mid range detail.,.. using a big driver in that way..

for the last 50 years the best drivers for mids upperbass/lower top have been around 8-9 " ... very with powerfull motors..

what am i missing...

steve

[NickG]

add spikes to the bases

Wouldn't that further hurt the bass response by affecting the speaker/floor interface?

Alnico 15" Jensen is quite an improvement

I don't know what I am talking about, but those Jensons seem to have a much higher Fs than the emms

[Richard Higgins]

Hi Nick
The speakers are top heavy and liable to rock on carpet, so I'll be trying spikes and adding weight to the bases.

Regards Richard Higgins

[Scottmoose]

Originally Posted by steve s

Thanks scott, so there not designed to go low is that right...
iam sure they are not missing much at the bottom still..
but lows on o'b is still a physical thing..
still don't quite get the point though.. i sort of would imagine a loss of upper bass mid range detail.,.. using a big driver in that way..
for the last 50 years the best drivers for mids upperbass/lower top have been around 8-9 " ... very with powerfull motors..
what am i missing...
steve

Nope, you're not missing anything really Steve. Note though that a lower Q driver will usually need a wider baffle. The Hawthornes should go lower than you might imagine -about 60Hz or so, based on the data I've quickly slapped into a spreaadsheet I have lurking around the HDD, though they start to roll off a ways above that (about 152Hz) due to the progressive acoustic cancellation. The extra bass driver will help with that.

Generally, they're pushing it, trying to get a big cone up as high as that. Compared to, say, a Lowther, they're not going to have the same transient speed & midrange detail, but OTOH, they shift far more air with that giant cone, and are a heck of a lot cheaper. Big motors are useful, but the baffle size would likely start to get a little out of hand. Different set of values really. As ever, YMMV.

[planet10]

Originally Posted by Scottmoose

It's deliberate guys. The SI drivers have a Qt of 0.91, & they're intended to work best on relatively narrow baffles.

Very much. Bob got SIs and we originally put them in a large winged baffle... Bass was HUGE and (according to Darrell) this imbalance was the cause for a hole where the midrange should have been. Bob says they sound much better with the baffles cut down. I haven't heard them since he did that. I still will reserve judgement... getting a 15 to go up to 3-3.5k to meet the tweeter is a serious challenge which even the very best 15s are barely capable of.

dave

[Paul Barker]

Originally Posted by NickG

I don't know what I am talking about, but those Jensons seem to have a much higher Fs than the emms

That's why we need to get together once in a while to find out where we are going wrong, aswell as what nice sounds we are getting when we deviate from conventional wisdom.

Blimey if I followed the pack I'd have to go back to my Flesh and Blood build days. That was a marvelous lesson.

These days,... find out "what is conventional wisdom on the matter?" largely ignore it.
find out "what everyone is raving about".. don't even think about it, because in 6 months they will be raviong about something else, stay where you are and wait for them to return if you are in the right place.

Fruthermore, don't bother talking about it because in six months someone else will have more time than you and create a web page about it, so become popularly referred to as the inventor.