Hawthorne OBs

[Richard Higgins]

Out of curiosity I decided to try Hawthorne Audios Silver Iris OB 15 inch co-axial speakers.
I had read about them in a review on TNT.
They cost £140 plus £30 shipping and £40 VAT etc and took 5 weeks to arrive. (Too tight to pay for airfreight)
The first baffles I made were designed to keep the speaker low to maximise bass reinforcement, but furniture placement killed any imaging qualities.
I made the pictured baffles to a similar size to the ready made speakers Hawthorne sell. They need felt adding to the rear of the baffle and finishing.



The biggest problem I have had with them is that they are very speaker cable dependant.
When I built my first valve amp I was using Linn Kaber speakers and eventually settled on TNT Twisted Twin cable in preference to Linn K600.
When I tried Klipsh Heresies they sounded best to me, rewired with IPL silver plated copper cable.
So when I changed to Impulse H2s I made up speaker cables as recommended by IPL, silver plated copper for treble and mid, and copper co-ax for bass.
One of the reasons for trying different speakers was that the Impulses lack a certain amount of air in the treble.
So I started running the OBs using some Cat5, platted, but not twinned, but the sound was splashy in the treble with limited dynamics.
After a month I changed to IPL silver plated copper, result, lack of air and sibilance, same result as using IPL with Impulses.
I then tried the IPL copper co-ax, this was an improvement, but there was still some sibilance. I then tried 1,5 solid copper mains cable, this was again an improvement, but sibilance was still present.
Finally I had a reel of 600v 1A 20 strand copper cable, so I used 3 lengths for each connector, result success, sibilance gone and impressions of speaker in line with TNT review. http://www.tnt-audio.com/casse/ha_si_part1_e.html

So these trials have taught me;
IPL speaker cable is not to my taste.
OBs work in a 11ft x 18ft room.
The importance of speaker cable.

I note that Cardas sell different speaker cables for different efficiency loudspeakers. I guess what is best for 200 watts may not be best for 2 watts.

What do other low power amp users recommend for speaker cable?

Regards Richard Higgins

[Greg.]

Hi Richard,

Nice O/B's. Is that one driver doing full range? It looks like you have a crossover so is there a tweeter somewhere?

I can't answer your question but thought I'd comment on your cable observations. You will recall we discussed your previous success with the IPL recipe. I went on and tried the IPL design but they performed exactly as you now describe with bright sibilance. I kept them in for a few weeks to be sure and with some listening help from others confirming my thoughts, I sold them on and returned to the TNT TT Cat5 design which does have synergy with my original WAD 300B PP clone through to WAD KLS3 MkI. I'm also convinced that the thing around cables is all about synergy which the industry has expoited to produce monster prices for some designs when in certain cases even bell wire might be best.

Are you bringing them to Eggfest?

Best wishes,

Greg

[prince of darkness]

Hi Greg'
Looking at Richards post, he descibes the drivers as coaxial. I take it they are similar to old Tannoys, where the hf driver is hidden by the dust cap.

[Richard Higgins]

Hi Greg
The tweeter is screwed into the centre of the main speaker and fires through it.
Yes its a strange business, this snyergy.
I found IPL worked on the Heresys, taming some of their energetic treble, but have come to realise they also dulled the more balanced treble of the Impulses, but dulled the mid range with the OBs.
Yes, I intend to bring them to Eggfest, it will be interesting to see how they compare, and what happens with more than 2 watts going through them.

Best wishes
Richard Higgins

[Greg.]

Hi Richard,

Thanks for the reply. I'll look forward to hearing them at Eggfest.

Best wishes,

Greg

[Scottmoose]

Likewise. It's a unit I've been wanting to hear for a while actually, so I'll look forward to it. Impressive looking beasts -I do love a big cone, especially if the driver's a co-ax.

FWIW, basically, the Siliver Iris is a custom version of the Eminence Beta 15CXA coaxial unit, built by them to Hawthorn's specs. Hats off to Eminence -not many other big driver manufacturers are as accomodating as they are to small companies. Another example is the main driver in the moderately famous Hammer Dynamics kit -also a custom version of one of their units, in that case the Beta 12LTA.

Anyway, the crossover & suspension are revised for the SI, as is the motor. Q is raised slightly because they wanted them to work well on narrower baffles, which makes a great deal of sense to me as more people are likely to be able to fit them in their homes. AFAICR, there are no cone mods, but don't hold me to that.

I'd avoid high resistance wire as you'll raise Qe, particularly with a low DF amp, so I'd make sure I went with something with a decent amount of copper / whatever. Some good DIY cable ideas / designs here: http://www.audioholics.com/reviews/c...-cable-faceoff

[NickG]

Yes, it will be interesting to compare with the std em beta 15 I use.

I am hoping that the nice new room at the next fest will let the various speakers show what they can do.

Well done Richard,
You can try all the cables available at the next meet.
I noticed some nice ally behind the speakers F1 by any chance.

[Paul Barker]

Hi Richard, not being critical but what follows are criticisms intended to invite discussion.

Considering there is no side sweep of any mention to the baffle (as used in James' designs) surely bass isn't intended to go very low in the original design?

Use of coaxial driver in this case seems flawed in that you've had to put the woofer right up there, where together with a small baffle there is no floor lift.

You have two speakers and acrossover, where is the benefit to OB in placing the tweeter in the middle of the woofer?

I've had a few dual cone Tannoys (Gold's, and cheaper modern ones without the Alnico), but was always glad to wave them off, usually it is the trebble characteristics which I don't like in the end.

I have usually found sibiliance is caused by cathode bypass caps in the amp.

[Paul Barker]

I do note however that Nick's OB's when driven by the right amp (like Andrew's Mig fighter one) have bass which I prefer to everything else I have ever heard except Bruce Edgars Sub which looks like the organ pipes at Westminster Cathedral. Oh and also the Organ at Westminster Cathedral which I heard one day whilst photographing a wedding. That was the best ever bass I heard.

So the driver has some redeeming characteristics and I am sure it is a good sound.