... Bert Doppenberg's ML-TQWT with Radio Shack 40-1197 (aka FE103s) ...



I needed to do some R&R on my amps so i moved the ESLs out and substituted these "tempoary" speakers. Ran them for a week from 2 NAIM 160s (1 channel/per driver). Over that time the quite prominent upper-midrange honk (particularily noticable on male voices) has slowly been dissappearing and these things are quite outstanding (and even more so when you consider there are less than $100 CAD in bits).

For the longest while i used them with extra woofers (i just slid them in where my ESLs were -- amps, XO, woofers and all), but lately have been using them FR -- i am VERY impressed with the amount of bottom end those 4" drivers can put out -- not anywhere near the equal of the Peerless, but their is a lifting of a bit of a viel when i take the Marchand XO out of the path. They have no need for bafflestep compensation since that is essentially dealt with by the rear facing driver.

I swapped out the NAIMs for a beater SE EL84 (the NAIMs are being tweaked). Lost a bit in the highs and the amp struggles if i try to play too loud (~160 cu m room), but they are very satisfying (really shows the exponential cost of small improvements -- swapping out $1.5k CAD worth of used amps for one that cost $0.075K used).

The drivers have some ductseal on the baskets and are otherwise stock. I plan on going thru a series of mods to them all the way out to phase plugs on the front driver. And i have a spare set if this is too far. The cabinets are made from a variant of baltic birch ply (swapped for a set of replacement drivers for the sales reps infinity bookshelf speakers) with a layer of laminate. The felt ring is pretty, but i haven't done any serious listening to differences with & without. Modifications & tweaks have been slow coming -- these are suffering from being so enjoyable that i haven't been keen on removing them long enuff to tweak them more. They benefit from a little extra on the top above 10k and i have been trying out many tweeters.

I have stocked up on some more of these drivers -- i'd like to see if Martin's model can show some room for improvement on the enclosures.

If anyone is any doubts about this combo, lay them aside.

<cliking on most images will take you to a larger one>

Tweeter of the Week

modified Foster alnico 50RT01 2" Cone

This is a Foster branded -- probably the OEM for the Sony below -- version of the alnico 2" thimble tweeter. I was quite impressed by the performance of these cheap tweeters (when i sell them i get $2 USD). I removed the dust-cap & added a phase plug. I shortened a 3M ear plug -- they are tapered and i had to make the base diameter a little smaller (probably need to shorten it just a tad more and get the cut straight). I then crazy glued a washer to the base of the plug and it is held in place magnetically. Initial impressions are positive.

Almost every week it seems i am passing thru another pair of interesting tweeters -- almost making a living by recycling hifi gives me access to many different ones. These are all being used as supertweeters with a nominal XO of 10k. None of the dogs make it onto these pages.

So far the Isophon above is the standout, with the others coming really close. Of the ones below the Coral domes & the shorter large Sansui & Foster tweeters (the latter not pictured) have the edge -- i suspect due to better time alignment with the shallow 40-1197s.

Previous Tweeters

Foster alnico 40-1166 2" Horn

This is the 3rd set of these i have played with. They have a longer horn than the one's below. I positioned them a bit forward from where i had them last time. The last couple weeks listening conforms these as one of my 3 favorites, along with the Coral dome, and the Isophon cone.

Hitachi/Coral Alnico 2" Horn

This is a very nice looking cast metal horn with a very large alnico magnet. Labeled Hitachi, from the evidence of the other speakers is probably a Coral OEM. Quite a bit too efficient for the pipes i have added an l-pad to bring the levels down. These are right up with the best tried yet.

Alnico Sony 2" cone

After the success of the Isophon cone i thot i'd try some other small cones. After a couple that didn't work out, i popped these on. They are quite good. Not up to the better ones that preceeded it, but i'd say ahead of the ceramic Audax. What is neat about them is that these are cheap, cheap. I have sold a number of pairs of almost identical Fosters for 2-bucks! Future trials after some surgery and we will see if they get better -- damar & a phase-plug (similar to what Dick Sequerra is doing with the tweeters on his mini-monitors).

Alnico Isophon 2" cone with open back

Best to date.

Foster alnico Horn Tweeters

Panasonic/Sansui T-60 alnico horn tweeters

Panasonic/Sansui T-157 alnico horn tweeters

Coral alnico 13mm dome super tweeters

Audax 14mm ceramic magnet tweeter

the mess on the top are 6 caps and a set of clip-leads for adjusting XO point

The FE103A Pipes

These are Chris' plywood pipes with alnico Foster FE103As. These are outstanding. The tweeters are Foster's very similar to the Sony's above -- they are almost unnecessary. The XO point hasn't been finalized yet but it looks like it will end up in the 13-15 kHz range.

The Red Pipes

At the same time Chris built my pipes he built himself a pr of mdf pipes for himself. These use the same Audax 14mm dome as above, but in a waveguide (mounted from behind the baffle) and are modified a bit to support the grills. I don't think there is a whole lot of difference between the mdf and plywood pipes, but Chris likes the plywood just a bit better. These are an example of how not to paint mdf, the finish is pretty but prone to scuffing.

  The following is a post from the Full-Range Forum:

Mr. Doppenberg's plan works, it really does. Last Friday I printed off the plans and picked up 4 RS 40-1197's. Saturday I cut 18mm MDF, Sunday I glued the cabinets together, installed terminal blocks, stuffed with some poly batten material, mounted the speakers and fired them up. They sound amazingly good for speakers that ran me perhaps $45 CAD each (including biscuits and glue). They definately lack wads of bass, but on the other hand they have great presence and crispness. I have a pair of JMLabs Profil 77's in one room and set the newly assembled TQWPs up against them. My daughter (who is not shy to tell her old man when he's strayed from the proper path) thought that the JMLabs sounded fuller and prefered them overall, but she did allow that the TQWPs were brighter and to her ear more accurate on vocals. Then we carted the homemades to another room where the standard speakers are a set of Paradigm 5's with a powered sub. This time, and this chagrins me no end given the $$ the Paradigms cost, my daughter picked the TQWPs. No contest in her mind. Only when the Paradigms were supplemented by the sub did she think they were even close to the TQWPs.

So to the newbies and fence sitters out there: if you have a Radio Shack in the area, and you own a dust mask, are strong enough to man-handle a sheet of 18mm MDF, and have enough clamps to squeeze the cabinets closed over glue joints, then give Mr. Doppenberg's design a go.

Happy listening,

peter rogers

TNT Audio Review of the ACR FE103 BD-Pipes

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