Mirror Image The Dahlquist DQ-10
The Premise
The imaging, depth and other sonic characteristics of the Dahlquist DQ-10 can be dramatically improved
by mirror imaging the driver layout (See the Before and After pics at the bottom of the page). This involves
swapping the board that supports the piezo super-tweeter and midbass with the board that supports the
tweeter and dome midrange on only one of the speakers. My DQ-10s have up until recently been non-
mirror imaged, but after some research, I decided to make the change. The modification gains validity
because the later models apparently were mirror imaged at the factory. It seems like a common sense
thing to do, since it’s not a new concept. But, it’s not as simple as just flipping a board. You’ll need to
carefully assess the situation and take some precautions, so let me give you the benefit of my experience.
You should be able to complete the project in an afternoon.
The Process
First, the tools:
Standard length and long shaft slotted and Philips head screwdrivers. The longer shaft will help you
negotiate around the panel board supports in front.
Utility knife.
Chisel.
Medium and fine sandpaper.
Drill with woodworking and metalworking bits.
Wood patch or spackle.
Wire trimmer/cutter.
6) #10 x 1/2” machine screws, nuts and outside star washers.
Soldering gun.
Hookup wire.
Masking tape.
Electrical tape.
Vise.
Hacksaw.
Visegrips.
Glue gun.
Re-sealable baggies for hardware.
Begin with a close to waist-high work surface. I used the island in my kitchen. Remove the
perforated cover and the frame. I saved any and all screws and hardware in re-sealable
baggies. Draw a map of the mounting board locations and distances from the front edge for the
new mounting holes to preserve the phasing. They’ll still be the same distance apart. I put pieces
of masking tape on the back of the drivers and wrote their orientation and the wire colors for
correct re-hookup. Snip the wires at the drivers and tape them together by driver for less
confusion later.
Note: I’d better say right now that I decided to leave the crossover where it is, only re-locating
it slightly rearward to accommodate the mid dome/tweeter board. The wires are so stiff that I felt
that it was tempting fate to move it any more, and it’s easier to jumper to the new locations rather
than doing a rework. The jumper distances should be inconsequential to the overall resistance. This
will place the midrange dome directly over a choke, but the voicecoil will be a safe distance from
and perpendicular to the choke, so any potential interference should be minimal. You may decide
to do otherwise.
Remove both boards. Remove the felt from the midrange and set it aside. I started with the midrange/
piezo tweeter board. My drivers were glued to the board as well as screwed. After removing the
screws, using the utility knife, very carefully start to gradually cut into the seal until the drivers are
loosened, remove and set them aside. Do your best to remove any fibreboard stuck to the driver
frames for the best possible contact. I covered the drivers in foam with masking tape as a precaution.
You are going to flip the board and will have to re-attach the brackets. The brackets are riveted in place.
Select a drill bit that’s nearly the size of a rivet back and drill them out. After the brackets are off,
grab the remaining rivet fronts with the vicegrips and they’ll just pull off. I used a chisel to scrape off
the glue left from the felt and then sanded the surface smooth. I didn’t re-glue the drivers. My midrange
had four screws in place but there were eight holes in the frame. Since I wasn’t re-gluing it, I scrounged
four more like screws, marked the new holes and drilled them out, then used all eight screws. Re-mount
the midrange to what was the back and is now the front, noting orientation.. Bolt the piezo tweeter in
place. Re-attach the felt with the glue gun. Re-mount the brackets with the machine screws, nuts and
washers then set aside.
Turning to the mid dome/tweeter board, by holding the board over the crossover, the brackets are
obviously not far enough apart to mount as is. Leaving the drivers attached, carefully wrap the drivers
with foam and masking tape. Remove the bracket that will be outermost, that is the left if viewed from
the back of the board. Put the upright bracket front into the vice and with the hacksaw cut off the angled
portion at the junction where the front and angled portion meet (the “top”). Re-attach the bracket to the
board and set aside. I think that the board is plenty rigidly attached without the one angled portion.
Turn your attention to the crossover. There were three screws holding it in place. Remove the screw
through the board and the two through the chokes and set aside. Move the crossover back so that the
wire bundle is just at the rear edge. If it’s too far back, it’ll interfere with the perforated screen. Drill
out the new holes and re-mount the crossover. Drill the new bracket mounting holes per the map that
you drew. Plug the old holes with the patch or spackle. Remove the protective foam and re-mount
the boards.
Note: Try not to drill all the way through the enclosure so that you won’t have to dismount the woofer
and vacuum the dust out of the enclosure; otherwise dust could potentially find its way into the woofer
voicecoil gap.
Driver by driver, note the wire distance discrepancies and install the jumpers. Be careful to move the
wires at the crossover as little as possible or you’ll risk doing some re-soldering. You can solder the
jumpers to the existing wires as I did or use solderless connectors, whatever you wish. If you solder,
wrap the connections thoroughly with electrical tape. Neaten up the loose wires. In my case, I added
dampening again to the mirrored piezo/midbass board after the pictures were taken. Clean up, re-install
the frame and screen and you’re ready to listen to your mirror imaged masterpieces.
The Verdict
You’ll now have the option to position them with the piezo tweeter and mid-bass or the tweeter and
mid-dome to the inside. After trying it both ways, I’ve settled on the tweeter and mid-dome to the inside.
It could depend on how far apart they’re spaced and other room issues. As good as they sounded before,
there were undoubtedly phase issues with the previous driver orientation. The imaging is now much clearer
and solid as a rock. Another interesting benefit is that the timbres are clarified and the bass is enhanced.
After extensive listening, I’d call this modification an unqualified success. It's not an overstatement to say
that the sound is simply thrilling. I'd strongly recommend that you make the change, or enlist whatever help
you need to pull it off. Drop me a line with your results and any suggestions, opinions or observations by
going to the Contact Best Speaker Parts page. If this site meets your needs and has been informative and
helpful, please realize that I can only keep it going for both of our benefits if you continue to make your
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Before
After
