Mass loading Tannoy Definition DC10a speaker.

I would use sand not lead. Are you attempting to tighten up the bass?

Thank you for your input. Possibly tighten the bass and make it deeper.  In general I am trying to get it to the next level, if applicable. I am happy with the way it sounds now. 

My dealer had a demo set of DC10A for years. They were loaded with lead shot immediately when received - your post just reminded me that I never actually heard them unloaded. IIRC something like 40 - 50 lbs each speaker? 

I've commented before that I'm not the biggest fan of DC10A's. This particular pair was bright, a bit lean, and definitely overdamped in bass compared to other Tannoys above & below that model. I'm wondering now whether the mass loading was a contributing factor - but I'm skeptical it could have this much effect all its own. I'd say not to bother adding mass, but then again you never know how your ears & systems will react until you try somthing yourself!

More recently I acquired a set of Kensington GR in the limited "Black Ash" finish. This has the same dull-silver (pewter?) colored horn as DC10A. Nowhere will you find any documentation that states this driver is ANY different than the usual gold-throated horn (Kensington), but I swear I heard a lot of the same things here as with the DC10A. I ended up buying a floating pair of gold-horn Kensington-OW drivers, and even though they were made in China (circa 2018), they sound decisively warmer and richer than the silver-horn drivers. I much prefer them, and feel like there has GOT to be some voicing difference with those silver-horn divers, and that perhaps the "Black Ash" Kensingtons actually used surplus DC10A drivers. Also used to own older Kensington SE (gold horns), both the SE and GR gold-horn drivers sound much more alike than the silver horns. 

Anyways, the silver-throated drivers did sound a lot better with a 3rd party crossover from MainlyTannoy (UK), though they're seemingly voiced brighter/leaner than the gold-horns. The gold horns also sound better with MainlyTannoy xovers - the stock xover in these Kensingtons was AWFUL. So I'd look at xover before mass loading, for sure. Food for thought, maybe :) 

My Cornwall 4's are easy to mass load from the bottom because of the 3 bass ports at the bottom facing forward. I used lead weights and found that at some point weight became counter-productive and actually boosted and distorted treble. The sweet spot was about 18 lbs of lead per box. More weight stiffened the walls of the box too much and perhaps contradicted some of the resonance designed into the speakers in the first place.

Mulveling, my experience with the DC10a is that it is balanced and warm top to bottom when I am not using the spike(just let them rest on carpet), I have very detailed bass, every note is there and it rattles the floor (in a good way I mean). Bass is full but the very deep bass(<40 hz is not that impactful but you hear the note clearly). Overall, it is a very visceral experience. When I put them on the spikes, the sound is a bit more detailed, and may lean towards being bright but not much. They sounded best with isoacoustics isopucks underneath them. 

I previously owned a Rel Gibraltar 2, and the deep bass was very deep-the thump- ( I know I am not comparing apples to apples here, but just to make my point)

Bolong, I totally understand, and this is my concern. It may be too much of a good thing, that is why I started this thread. The other concern, if I don’t like it, it is very hard to get the sand (or anything else) out, since the opening is about 2 inches and the box is bigger, there will be some residual sand there. If it is lead shots or atakama atabites, if may be easier to drain. I can’t shake a 100+ lbs speaker (like a salt shaker)  to get the sand out of the circular 2-inch port J

The other issue is that I liked the isopucks and I may buy GAIA II which support up to 120 lbs speakers. If I load beyond 120 lbs, then the GAIA IIs will be useless, and I have wasted $600.

Maybe I can start gradual mass loading, 2 pounds at time, and see where the sweat spot is. If I exceed and want to go back, I have pull back to the previous weight (sweet spot) and leave it there. I was hoping for someone to tell me this weight, so I don’t have to guess nor do this experiment. Tannoy has R & D and they should have provided some guidance rather than an empty compartment and a few lines in the manual about mass loading.

Thanks again

Whatever you try, make sure to enclose it in a strong  "bag"  for easiest removal/testing.

Thank you so much Slaw, This Is a brilliant idea. I can even use multiple small

size bags in increments so they are easier to get of the access port. Thanks 

What are your components up stream?

I would decouple the speakers from the floor see here I would also put two cement bricks in each speaker: cement bricks shall be 2''x4''x8'' (not clay bricks) see here good luck. 😎

Mike

Thank you for for the excellent suggestions. 
component:

power supply : dedicated 20 AMP line>shuntaya 20 amp power cord > Furman elite 20 amp > out of the high power non filtered outlet comes out synergistic research atmosphere sx excite feeding a power cell 8. All hear  is supplied by this power cell.

 Power cords: Ansuz acoustics A2 to all components 

front end: Eversolo dmp- dmp10, Ethernet AQ cinnamon 

premaplifer : PA audio BHK signature preamplifier ( stock 12AU7 tube)

amplifier : Cary adio 200.2 ES

interconnects : from Eversolo to preamp = audience studio one Xlr , from preamp to amp= Kubala- Sosna Emotion Xlr , from amplifier to speakers = Kubala- Sosna Emortion speaker cables , KS  jumpers  for highs in the DC10a

Thanks  for asking