Hestia OB, an ambitious low cost, 3-way OB design

ThePriest · « **Reply #160 on:** 30 Jan 2014, 09:10 pm »

Hi Matevana.
I have recently become interested in OB speakers, and I'm impressed with your build, the simplicity appeals me.
I would like to build something inspired by it.

Do you think it would be possible to have 4 of the MCM's pr side, still observing the distance between then as per the Hestia?
I have a 135 cm long ribbon speaker, that I plan to use from around 1200Hz and up.
The ribbon sounds great, and I hope to extend its openness to the frequency range below.

Regards,

Mikkel

matevana · « **Reply #161 on:** 31 Jan 2014, 01:55 pm »

Hi Mikkel!

I think it is totally possible. Four of the MCM drivers per side wired series/parallel would yield an easy 8 ohm load and be very efficient. You may even want to consider a shallow H-Frame housing all drivers. or H-Frame on the bottom and open baffle on top. It would be possible to do that in a shallow cube as small as 25" x 25" x 12".

Ed

ThePriest · « **Reply #162 on:** 31 Jan 2014, 02:22 pm »

Hi Ed, thanks for your reply.
25"x25"x12", does that imply you mean to put the drivers in a square, 2x2 arrangement?
I was thinking 1x4, along the ribbon. More in a line source inspired way, if that makes sense in the OB-world.
The H-frame could then cover the two lower drivers, perhaps?

Cheers,

Mikkel

matevana · « **Reply #163 on:** 31 Jan 2014, 03:13 pm »

You could, but a 2 x 2 cabinet will give you more bottom-end, since two of the LF drivers will benefit from floor bounce. It really depends on how high you plan to cross to your ribbons. If you are hoping to get better vertical dispersion of the lower mids, the column approach will work well. However, if your ribbons are capable of producing ample low-mids, you would be better off crossing lower and having more of the LF drivers close to the floor, in my opinion. In the Hestia-Forte design, the 2 x 10 bass cabinets can be placed either vertically (like Orion) or horizontally (like Martin King's Lowther/Acoustic Elegance H-Frames). I much prefer the horizontal placement in that design.

ThePriest · « **Reply #164 on:** 1 Feb 2014, 07:50 am »

Good point about the low end.
I currently I am using the ribbons from around 1200 Hz, with a passive, fourth order filter. They can go as low as around 1000, but start to sound thinnish.
I think I'll start with two woofers horizontally in an H frame, and two stacked vertically along the ribbon.
For a start, they will be driven by the same amp, and thus receive the same frequency range, as I only have four amplifier channels. I am using a digital filter for the low end, and can match levels and do a bit of equalising that way.

Cheers

Mikkel

matevana · « **Reply #165 on:** 20 Feb 2014, 03:33 pm »

If anyone is interested in building these, I have about 10 of the Dayton 10" pro sound drivers in a bulk pack. I will let them go in pairs only. Just make a reasonable offer.

lloyd bruney · « **Reply #166 on:** 28 Feb 2014, 02:35 pm »

Hi Matevana. I have all parts to construct the Hestia using three mcm drivers per side. They were on sale for 14.95 over the holidays. I constructed the cabinets with a u frame for the bottom two woofers. I will be powering with a tpa3116 for the top end and a yung 100 watt plate amp for the woofers.My problem is that I am quite the novice in crossover building. I have seen the diagrams but do not understand them. Could you draw a simple picture of the crossover board with parts and solder points and speaker hook up. Thanks for sharing your knowledge and passion for our hobby.Lloyd Bruney

matevana · « **Reply #167 on:** 1 Mar 2014, 01:32 pm »

Hi Lloyd,

Sure thing! See the diagram below for the connections. C1 and L1 represent the capacitor and inductor pairs for the tweeter; C2 and L2 for the woofer. Typically the (+) and (-) connections furthest from the speakers get wired to the (+) and (-) ends of a speaker terminal, so you can easily unplug the speakers as needed. If that still isn't clear just email me and we can go through it in more detail.

Ed

OB_Newbie · « **Reply #168 on:** 9 Mar 2014, 02:01 am »

Hey Ed,
I suppose the Dayton 10" pro sound drivers are gone by now?

Thanks!
Rich

matevana · « **Reply #169 on:** 10 Mar 2014, 12:44 pm »

Hey Rich,

Yes, they went quick. I basically did a BOGO (plus shipping) for those who might be interested in building one of the Hestia designs.

Ed

kephas · « **Reply #170 on:** 4 Apr 2014, 10:23 pm »

Hello,

I am new here and new to OB speakers. I have been running an active 3 way system for years with box speakers and crossover points at 100Hz and 2800Hz.

Can you, Matevana, or anyone suggest a set of reasonably priced speakers for my first OB experiment that would work well with these x-over frequencies ?

JJ · « **Reply #171 on:** 9 Apr 2014, 07:03 pm »

Another complete newb piping in...could the Hestia be made as a 2-way system (just the tweeter and the MCM doing all mid and LF duties)? If so, would a person want to keep them on the baffle where they are, or would centering them (top/bottom) drastically effect the sound?

matevana · « **Reply #172 on:** 13 Apr 2014, 06:07 pm »

Hi JJ,

The short answer would be no. To effectively build this design (and many other OB designs) you need a way to bolster low frequency output if you're goal is to have a design that reproduces sound close to full range. This is necessary due to the 6 dB per octave roll off behavior that OB speakers exhibit. The easiest way to compensate for this roll-off is to have a dedicated low frequency driver (helper woofer whose volume is individually controllable). If you ask the MCM driver in this design to reproduce a range from Fs (it's resonance or lowest frequency) up through the crossover frequency of the tweeter, you will wind up with a curve that is anything but flat.

newbie7800 · « **Reply #173 on:** 29 Jun 2014, 08:41 pm »

Dear Matevana and fellow Hestia OB owners/builders

1.5 years from first thinking about this project I am almost there with lots of ups and downs for a total beginner. Pircture attached to prove I am actually progressing. Holes all cut and crossovers ready to build. I even understand the crossovers

. However one simple thing stopped me tonight building them. How can I use the cableties to fix the coils. There is only 1 hole in the pre-etched boards from PXpress. It would be far easier surely with two holes. Can I drill extra holes. I looked at the pictures and I cannot see how to do it with just one hole securely. Sorry for such a simple and dumb question but it is stopping me progressing to the final stage!

Regards

Newbie7800

matevana · « **Reply #174 on:** 29 Jun 2014, 08:49 pm »

Hey Newbie!

Great to see the progress. Should be pretty easy to drill a 2nd hole in your board. Are you able to upload a pic of the board you are working with?

newbie7800 · « **Reply #175 on:** 30 Jun 2014, 10:19 am »

Hi Matevana

Thanks for replying so quickly! Once the build is complete I will for the fun of it share all the trials and tribulations I had learning to build these things (including the last one which was a power drill I purchased for a hole saw to cut the tweeter holes which had a keyless chuck which was totally useless and would not hold the bit in place

) - just survived cutting the two tweeter holes. If I ever do another project again I have to learn how to cut tweeter holes with the router

).

The board is the same as what you suggested to get in the first place. It has the white circles on it and clear markings for L1, L2, C1 and C2. It is the same as the pictures of SJhomey (the red tall Hestia's

- I used the same measurements for my panels as you can see

). They have one hole per coil. I did not want to drill into the board without confirmation in case I was destroying any circuit

. I really can't see how to do it with just one hole. Sjhomey has two cableties across the top coil in his pictures which looks nice and secure but this would surely need 3 extra holes drilled for the top coil (plus the one already there)

matevana · « **Reply #176 on:** 30 Jun 2014, 12:37 pm »

Gotcha. Drilling the extra holes similar to what SJHomey did should be fine. I have also had good luck using heavy duty hook and loop tape (velcro) sold at Home Depot. One side adheres to the board and the other the bottom of the coil. You can then remove and reposition the coil as you need to. This works well if you didn't want to go the cable-ties route. It also keeps the coil from vibrating against the board (especially in cases where the board is attached to the baffle). I have also had to remove the velcro tape and it did not damage the coil or the board. Here's a picture of the stuff I'm referring to. If you are interested, Just be sure to get the heavy duty velcro, sold in tape rolls about 1.5" wide. You can cut it into a circle, just smaller than the coil bottom. If done right, you wont see it once the coil is mounted.

motosapien · « **Reply #177 on:** 1 Aug 2014, 02:48 pm »

The MCM/Vifa top looks very good. I'm thinking of trying it with the 15" GSR in this design http://www.audiocircle.com/index.php?topic=99369.0

A 24" baffle width at the bottom tapering to 15" up top. This would raise the tweetr level up to ear level. Having to purchase the plate amps is a bit of a stumbling block but the flexibility they afford in integration is attractive.

motosapien · « **Reply #178 on:** 31 Aug 2014, 05:08 pm »

The vifa tweet is out of stock. Not due in until October now. Was thinking this one might work well;
http://www.parts-express.com/phenolic-ring-tweeter-8-ohm--270-252

People seem to like it's mellow sound and the price is in keeping with the design goals.

matevana · « **Reply #179 on:** 7 Sep 2014, 02:22 am »

I may have an extra pair of Vifa D19's. Either way, I would stick with a 3/4" dome for this design due to its dispersion characteristics.