My Big Active Speaker Project

[Primalsea]

I know that most of you guys are valve fans so I'm not 100% sure that this will be interesting to anyone, but here goes.

Heres a pic of my big speaker project. The drivers are Seas units and the cabinet is a 100 litre and fully closed. This gives a healthy bass extension down to 42Hz.

I've been working on these on and off for over 2 years and soon will be ordering the faux leather to cover them. Then its down stairs with them, probably in some kind of penned enclosure to allow Kerri time to get to know these strange creatures that are invading her personal space. Yes these have very little WAF.

The amp is solid state so I know some of you guys might have a issue with that. One pic shows the last 2 channels installed but not wired yet. This will make 6 channels in total which is needed as this is an active crossover speaker unit.
The amp has 2 450VA toroid's undernieth the plate which the smaller toroid and the low current power supply sits on. The whole power supply is in a drawer which can be completely removed for testing or further modding later on.

having the low current sections of the amps feed with their own supply make a great difference sound wise. The amp can also be set up for seperate high current supplies feed bass and treble/mid seperately or left and right channels seperately. I prefer left and right channels being feed seperately as there is a better sense of stereo seperation.

This amp has become somewhat of a reference for me to base my feelings about other amps. The only thing I feels it lacks is that wonderful mid range that valve amps have which I find quite seductive.

I just hope that the speaker's perform the same way. If they end up not faring too well in a shoot out I will probably cry.

[Primalsea]

some more pics

Nice.
Tell us more about the 'speakers though ...
Sensitivity? Drive units? Crossover frequencies? Closed mid as well as bass? Etcetera!

[Scottmoose]

Speaking for myself, I have no issue with SS at all -I stick with it too. Nice work indeed.

[Primalsea]

I did'nt have much time last night to go into too much detail. The drivers are Seas P25REXDD for the bass, MP14RC mids and 25TNF tweeters. Sens. is 90db. The mid has it's own enclosure which is really a pudding basin with layers of bedsheet and pva glue for dampening around the outside. The tweeters are closed so I did'nt make an enclosure for them.

The crossover is an active 24db/oct LR unit that I bought and modified by beefing up the PSU for cleaner voltage rails. It has adjustable crossover frequencies. This allows plenty of scope for experimentation. Eventually I might make a passive crossover using the frequencies chosen from the active unit for comparison. I have only done some preliminary tests in my small spare room, The room interaction made it completely impossible to make any proper judgements.

When I get a willing helper to carry them downstairs I will try them in my much larger living room which is well damped with sofa’s and curtains.

It’s not very clear in the photo but the sides are curved and the back is sloped to minimise any parallel sides. The inside is lined with expanding foam. The main body is made from chipboard and the sides from layers of hardboard that are glued together. There is an outer layer of roofing felt which is covered with heavy canvas dipped in PVA. The baffles are covered with a few layers fleece. The idea is to have a dampened cabinet rather than an impossibly heavy one. The fleece I hope will minimalise any interaction with the baffle plate.

The width of the baffle around the bass driver hopefully will give a baffle defraction of around 300hz which will be the crossover frequency. The plan is to boost the bass level to compensate for this. The mid/treble XO freq is 3000Hz.

I should have the faux leather in a couple of weeks and then the covering will begin. Here the plan is to have a pull over cover that is tailored to fit nicely around the cabinets. I did’nt fancy the usual wood finish.

[Primalsea]

Here some pics