Gallo Solo/Reference improvements

Speaker Asylum

General speaker questions for audio and home theater.

There's been a fair bit of speculation on this site about what's inside the Gallos and how to get in there etc. As I had the misfortune of knocking one of my balls over, so to speak, I had to repair it. Further more, whilst I was there I decided to biwire and improve the crossover. (I have two References and three Solos)
The plastic rectangular bits you see x 6 on the outside of the 17W75XL Dynaudio drivers are plastic rivets. The only way to remove them is to carefully drill off the head. Then cut them off from the inside of the sphere and pull the remainder out from the front of the sphere. This obviously poses the question on how to replace the rivets. You could ask Gary Pelled for replacements (although they've been out of production for years), but here's the drum...
On the inside of the woofer is a bitumenistic goo which is used to seal the driver air tight to the sphere. This stuff sets a bit like blue tack and really all you need is some screw threads with around a 3.5-3.8mm diameter to 'hold' the woofer position - note how each diverge tangentially to the sphere so as long as they are snug the woofer can't fall out. Whilst I was lucky enough to get some hardware from Gary years ago (after many many followups I might add) I have not pulled the new rivets heads off to engage the rear of the sphere. None of the rivets have fallen out since pushing them in. Alternatively you could use black or clear silastic. I looked for some time for a readily available off-the-shelf hardware solution - nutserts wouldn't fit in the small holes since there's very little clearance to the circular opening for the woofer and standard plastic press studs aren't deep enough to go from the outside of the woofer frame to the inside of the sphere - some 13-14mm. Perhaps Aralditing nuts to the inside of the sphere could work....? Problem then is if they DO brake loose, you'll never get the woofer out again... :(
Inside you'll find a bunch of white acrylic wadding used to damp the only resonance - that of the diameter of the sphere (It would be good to find something a bit more efficient acoustically than this stuff - let me know if you know of something a bit coarser). There is also a foam 'sock' over the port to eliminate chuffing. The crossover (funny the literature said no crossover...) is attached by the same bolt which holds on the tweeter. The tweeter is effectively a piezo device which is transformer coupled. Once you've desoldered the wires to the woofer, you can pull out the wadding, and then with a 1/2" spanner, carefully remove the crossover and transformer. I recommend cutting the leads to the transformer at the speaker binding posts as desoldering inside the sphere is extremely awkward and frustrating!
Everyone has favourites for crossover caps, but in my experience the Auricaps are the best (see my review on Audience's website). They are not only relatively cheap, they have great transparency, extremely low colouration and they are fast. The cap in there as built is an Infini cap of value 5.15uf approximately. I used 5.25uf Auricaps, see later for end sonic results. Connect the red lead to the RHS when looking at the resistor face on.
I see that someone on this site has recommended taking out the 5R resistor (gold heatsunk RS catalog type) there in the crossover circuit. I caution against this for a few reasons. Firstly the impedance of each woofer is around 3.6R and the transformer primary has only a fraction of an ohm impedance. The resistor is in parallel with the primary winding. It is also used as a shelving resistor I believe in this configuration. Removing may change tonal balance significantly and make it harder to drive from an amplifier point of view, especially at low frequencies where your amp will see next to nil impedance....!!
After removing the crossover, I then removed the tweeter and placed the first nut I removed on top of the sphere to jack up the tweeter a few mm. This allowed me to remove the internal wiring so I could biwire. Gooped up the small wiring hole with some of the left over bitumenistic goo. I used some silver and silver/gold alloy strip I use in my cable designs to make the biwired cable for the tweeter.
After carefully restuffing the wadding evenly around the sphere, I pushed up the bitumenistic goo on the woofer so it could remate with the sphere again when pushed back onto it. I also cleaned the mating surface with sugar soap and removed previous traces of goo etc. Resoldered the wires, paying attention to original polarity and carefully alligned and placed the woofer back in its original home. The the plastic rivets were placed in each hole to stop it falling out.
The sound? I loved these speakers from the very first day I found them, when I wasn't even looking for speakers at this price point and found I just HAD to buy them...from my measurements (I have a DSP8024 in my system) the as designed Gallo Reference is a little laid back in the top end, especially from around 8k-20k in the order of up to 5dB rising gradually over that range. Talking to Gary no plots of the speaker's performance are available from Gallo, as they tuned them by ear...shyikes!
Well the Auricaps improve things similarly to how they improve circuits with coupling caps. More transparency, more efficiency, more engagement - obviously I am hearing the benefits of biwiring also. Even though I am correcting my room response with the DSP, the end result does not end up sounding in any way forward or harsh. I just get up after realising I listened to the whole CD when I was only planning to listen to a single track. At the moment I have not changed settings on the DSP, although I may reequalise to see if further improvements are now possible.
If you have these speakers already, or are about to buy a pair, seriously consider this modification. It's cheap, and relatively easy to do if you're DIY minded and careful.
Note - I will not he held responsible in any way if you try this and stuff it up for whatever reason. I offer this advice in good faith and believe it works as described. Get expert help if you need it.
Cheers, Kendrick

Cheers, Kendrick Pavey

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Topic - Gallo Solo/Reference improvements - Silver Stealth (was Triode Dude) 20:28:21 03/25/03 (0)

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