"FAIL SAFE"

Choosing the right "hi-end" speaker is very diffcult. Even limiting the choice to the DIY world, nowadays there are plenty of projects and drivers to play with.

Starting from the little bit of experience our gruops has reached through these years, we've find very useful these two guidelines:

1) try to listen  before embracing the most expensive projects.

2) use of course high quality components (ins't it called high end??)  but in  well known/experimented projects

The first is a safety guidelines that made us spare a lot of time/money. Once you've found the speaker of you dream, in our experience it's better to wait a bit, and make a trip with your best friend (4 ears are better than two)  to listento it  in a show room or in a private house.

Better is succeding to have the speakers you want connected to your amplification system (you can take it with you) and best..... of course  to have everithing in your listening room.
In many ways this could be a dream, expecially in the hi-end  DIY market,  where very often  there are few exemplars built arond. Besides, as results could change drammaticaly in cosequence of one set of building choices insteda of another (or can be improved through the path),  you can't always have a final judment on a project.

Always try to take any decison after a while.
Beside remember  that one great problem when you judge a speaker  for the first time is the "psychological pressure" coming from the enviroment: (from the sales man, to other people arond and even your friend). Everithing around tries to keep you away from the truth: that's exactly what your ears are receiving. So try to  "keep you mind cool".
You'll discover  sometimes that the more money/effort  isn't worth the result or that what you've at home was  not so bad if not definitely better ;).

The second guidelines is another "fail safe" advice we've find very useful expecially in DIY markets, where new projects and lately also new drivers are a monthly costant.
I'ts better to embrace projects well known among the DIY community, using drivers that are well experimented.  So even if you'll be disappointed with the results, your speaker will always have little  more  "market value" or at least you can re-use the drives in another project. ;).
Everyone knows It's very difficult to re-sale used speakers of very famous labels, try to figure out what you can do with a  DIY speaker!.

In other world when you choose a DIY high end project and money matters, is better to be a "follower" than an "innovator" ;)
 

I've always keep on  searching  in the internet for DIY horns.  There are many nice projects.
I've considered for some time to "spend the least  and have the best" using another Fostex Dirver.
I made some steps in building the nice  Jericho horn using Fe208 but, at the end I decided to make a bigger step and use another supplier for the driver. But Who?.

My choice at the end  was quite conservative. After listening to several  diffent drivers using it,  choosing  lowther drivers was quite natural.

Having fixed the driver, I found more difficulties searching  the "right" cabinet.

Luckyly I had the chance in a couple of Italian Hi-Fi show ("Milano high-end" and "Top Audio"), to compare lot of DIY project using lowthers (Side vivace, Fidelio, Belcanto, Hedlunds, Mauhorns... )At the end choosing Hedlunds for me was easy and in some respect cumpulsory.

I had little space so I couldn't host a pair of vivace/side vivace in my livingroom.
Besides after having listened to Fidelio, Belcanto and Mauhorns, I preferred  immediately the sound of a front horn, quicker and very straigt compared to the slower and softier sound of rear  horns.

Hedlunds  were  clearer, bass wasn't so deep but very quick, thanks to their vertical shape they occupied little space... and....   they looked definitely smart... ;))

So the coiche was another time quite natural.

Next step was the classichal "make or buy" decison. I quick survey on the italian  "buy market", discuraged me, there where too many choices but no-one completely satisfaing me and the prices where definitively high: i was asked  even  9.000.000 ITL  (4.500 euros) for a couple of spekers.

I was turning to the "make" solution until searching the web for the latest news on the making process  
I found  Miroslav, a Croatian DIYer  that sold  a nicely veneered version, for a very cheap price.
I quickly contacted him and in a month I had them in my livingroom ... and today  I could really said  Thank you Miroslav and to your  woodmaker "kruno", he did a real "work of art".

Everithing ok then???    well.... no .....I did one *big* error in all that: I had the cabinet ready before having bought the driver.
The period i received the cabinet was jenuary or thereabout and te drivers arrived lately in april.
I leave you imagine what it means to have two hi-end cabinets in you living room without listening to them. .. I had *very*  hard time then.....   :))))))))))))

Next problem was "wich lowther should I use" ???.
Although Hedlund were originally designed for DX2, I had the chance to ear a modified version for PM2a by ikarus. Medium and high frequencies were better but you'd to modify the rear chamber to allow enough space for the PM2a magnet.

But what about the new   Ex series?.
I did a little survey in the most famous discussion groups (Audioasylum, Melluish, egroups), and asked to Hedlund Himself.
He told me that best known result were with Ex series, also Bert (Doppemberg) comfirmed that, adding that I could have a big improvement using AER modified version, but the rear chamber of the horn needed to be a bit re-tuned.

At the end I opted for new the recently introduced EX3. .  This series has smaller magnets dimension thanks to the use of new rare earts and a new chamber to reduce the rear emission of medium frequencies.
The latter  is an important detail in hedlunds, as in this foreshortened horn there is a considerable emission of medium frequencies from the month.
One disadavantage of the use of these new magnets is that they're very sensible to temperature: they loose  easily their strenght in consequence of thermal shocks. So beware...
 

Here are the graph of the response of the EX3 my supplier (Digitex) gave me:
 

DRIVER A

DRIVER B

As you can see there are some slight differences among the drivers. but not so high in my opinon: after all they're "hand made"!!!.

Here is also a graph of the impendace response (only for driver A)

As you can see i've choosen the 16ohm version with silver coil. This is the best choiche for SETs. Connecting a 16ohm driver  in the 8 ohm taps result in doubling the load impendance of the output tube. So you'll  have less power  but you'll have a great improvement   in distortion.
 

If you put and ex3 inside Hedlund cabinet, you have to do a little reworking to allow little more space fo the rear chamber. Things are very easy and you can do it by yourself.

Simply put a little paint on the rear chamber of the EX3 and see where it touches the cabinet.
Using a pen draw a little circular reference line of about the same profile  of the rear chamber.
Then using the drill dig a little hole taking away the wood that is in excess.

You won't have any problem of runing the speakers or cutting a pass-through hole, as you've to go deep only for 4-5mm and hedlunds are 25mm thick.

Frequently put the speaker in place and see if is necessary to deepen the hole.
In the following photos you'll also get a little trick in order to simplify  this  put-and-remove fase.
 

Here are some photos of Andrea creating th hole.:

Here is the result. To avoid powder or little pieces falling from the worked part, It's advisable to fix the surface of the hole  painting it with trasparent paint or glue.

Here is alittle trick to lie in place the driver without damaging it.
 

Near the end....

Here is the final result:
 

First Listening Impressions
 

Frankly it's too early to have an idea of the real "timbre" of the speaker.
Lowther have a very long (and controversial) burning-in period.

In our experience:
 

• First "30" hours: according with manufactuer advices, you need to play at very low volume. In this period You've the idea of dealing with 2 "supertweeters".  Sometime you think  you're crazy spending so much money for those speakers sounding "like old little japanese radios". Keep cool ;)
• "From 30-100/150 hours".: You can put more power, but sounds come out very "dirty", still all in the high register.  You feel there is something improving but with very little steps. This is the hardest period: you realize  it's a long way.  Remember that burning in period advance if you listen at "normal" level. Listening at very low level slows the process. Computing time try to be honest! 
• "From 100 to 200 hours".:Bass start to appear, Voices are improving fast: here is each week more clarity in the sound. Also the "speedness" sensation start to improve. With my couple of Ex3 I'm in this phase now.
• With a couple of PM2a in a Side Vivace cabinet , we've exceeded 700hours of listning time. What became clear as times passes, is that you'll have more balance in the emission and also highs and speed  keep improving.
  In other terms sound seems more open and natural. Thus, as time passes,  we're more and more convinced that the "buring-in" period of this speakers will never end.  Someone says they sound best before they got broken for the age!

Some Last Minute's Tips.
 

To reduce medium frequencies emission from the mounth of the horn i've used with good result a simply damping soulution in  the last part of the horn.

I've prepared a square sheet of cork dimesion 225x900mm. I 've bought those sheet of corks used to insolate room from noise, these are about  3-4mm thick.

On the cork  using bi-adesive strips I've put a layer of those  loose fluff that is sold in "fabric houses", and used to fill winter dress of covers. Thickness is about 15-20mm. 
Instead, you can use  the fluff is used in kitchens for adsorbing smoke in the fans above the fire places.

This combo is placed right in the last part of the mouth. Remeber to lay it right against all the curve pressing it gently. It will hold in place without any  other trick  thank to the friction of the cork against the wood.

With this tips, sound seems to slow and arretrate a bit. The "presence" effect is reduced, music seem "softer" but  -as a result- you'll be surprised by the bass richness.

That's all folks, Listen  and ENJOY!
 

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