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Thursday, April 20, 2017

The Journey to Open Baffles and Tube Amps

This blog is a journey into the wonders of hi fidelity. As I travel this path it opens up more and more.

My first memories of hi fi was my dads dynaco tube amp that he built with a pair of AR3 speakers. He had a cassette deck and I used to listen to Simon and Garfunkel Bridge Over troubled Waters over and over through a set of headphones.

My first real stereo was a JVC PC-11, half boom box half component stereo. It was around 20WPC and was pretty cool at the time.


Later I bought a Pioneer turntable to go with this system.

My first set of speakers was a pair of Mission 700S and  we had that connected to a JVC JR-S301 and then some sort of Sansui amp. Both the JVC and the Sansui were great at frying the Vifa tweeters in my missions at that time. Heavy fingers on the volume.

My first decent receiver was a Harmon Kardon HK 380i, a step up in sound and lots of head room. I stopped blowing tweeters.

Next came a Rotel RA-840B amp that ran 40WPC, I chose this over the AR Cambrige A60, although in retro spec I should have bought the AR.I had the Rotel for many years and just recently sold it in the past couple of years.

My next great pair of speakers was a pair of Energy 22's which I had for at least 20 years of which has seen some time on this blog.

It was the first tube amp that really sent me down the rabbit hole. The fidelity you get from 1 or 2 watts per channel can put the biggest monster receivers to shame.

Since being bitten by the tube bug, I have not really cared for solid state stuff and pretty much pass over most of it unless there is an end game for the stuff I pick up.

The tube amp has opened the door to speakers and their design.

In my journey I have found that the early well designed speakers from KLH or EPI with minimal crossovers are the best, after all in is signal in and signal out. Keeping the path of least resistance is the key.

When running a tube amp, speakers need to be over 90db in efficiency and the higher the better.
Another thing I found is horns in the mid range and tweeters give incredible clarity of which paper or domes can not. Some can come close.

Now I am finding that open baffle speakers are really clean in sound and the reason speaker were ever put in a box was to make them a piece of furniture that a wife could like. The bass in an open baffle is really clean as if the box imparts plenty of resonance, colouration and a myriad of other problems.

Open Baffles need a special room or space to work properly. A few things I have discovered in the open baffles is Alnico drivers work best, minimum of a 10" woofer is needed, a 3-5" full range is optimal for the mid range, preferably open in the back to get the proper refraction. I tend to like a horn tweeter to top the music off.

Of the open baffles that I have built to date this Foster Open Baffle is stunning in its' sound. I had to tame the tweeter down a bit with a resistor. The little Foster 8F3 full range is spectacular, a massive open sound stage is presented while the bass is really articulate, tight and clean with the 25E33.




So as the journey continues I have decided to sell off many of my boxed speakers and will concentrate on building what I think from my ears and years of experience some vintage cool efficient open baffles.

Stay tuned I have about six unique designs in my head and the drivers to create the path into this wonderful hobby.

I leave you some things to read and ponder.

Linkwitz Lab conclusion on OB versus box speakers.

Hawthorne Audio on the Art and Science of Open Baffle speakers.

Speaker Projects.

Good luck on your journey and I hope if you read this far try a tube amp some day and if you get the chance a really nice pair of open baffles.

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