Doc modding Marantz imperial 7

[Daniel Quinn]

As I only ever listen on axis, not bothered, but other factors are interesting.

[Latteman]

I have just bought four 6..5" mid bass drivers Must be the Christmas juice to blame

[karatestu]

My speakers are going to be made of some of these

https://www.tiles-direct.com/black-s ... p105

30cm2 x 10mm thick A 30cm cube will have an internal volume of 22 Litres which is ideal for a bipolar with up and down firing 6,5 inchers

Shiny black quartz will look a bit like black acrylic but half as thick and a lot cheaper. Cutting straight lines in tiles is no problem. Round driver cut outs are a different matter

[Ithilstone]

Cutting straight lines in tiles is no problem. Round driver cut outs are a different matter

Round driver cut outs - well that was my first thought - how?
I know of drill attachment to make holes in that kind of material
some even big enough for tweeter but holes for 6,5 inches?
if exists will be rather expensive and hard to get I would think

[karatestu]

Diamond core bits are available up to 152 mm which will be enough for a 6.5". I saw a 145 mm one yesterday.

It is tricky to cut quartz. Diamond is needed as quartz is one of the hardest materials. Go slowly with a slow speed drill and plenty of water to cool down the quartz and the core bit. I can use such things for other work around the farm and house so not wasted money for me.

Given that (my research shows) MDF resonates at around 1000hz and ply at about 2400hz, yet quartz resonates at 32768 khz is this a good thing or bad thing? There can't be much energy up at 32 Khz.

[Ithilstone]

32768 khz ? or 32768 hz

[Fretless]

[karatestu]

Oops. The vibrational frequency of a quartz clock is 32.768Khz. This has nothing to do with quartz tile. I expect it will be higher than most things but obviously not 32Khz. I copied something in here without reading it properly

[karatestu]

Well look what turned up today......



Four 6.5 inchers That is 280 cm2 of cone area per channel versus the 160 cm2 of two 5.25 inchers . For comparison, a single 8 incher is 220 cm2. !Happy New Year

[Latteman]

You have inspired me to dabble again- not the same but in the spirt of your photo I’ve bypassed the front tweeters and am using the single on an ‘open’ baffle to get it in a similar position to your mini tweeter cube
Amazingly I’ve not lost the tweeter sound- thought it would get swallowed up but there is definitely no deference - I’ve got to listen to them more- one question though- being an advocate of multiple tweeters I want to add a second but unsure where. I’ve considered a 90 degree inward spin of the whole speaker and use the top tweeter with the external one relocated to the ‘new’rear panel - what do u think (Stu)