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

motosapien · « **Reply #220 on:** 13 Nov 2014, 12:32 pm »

The MCM/Vifa combo sounds sweet. The MCM is quite revealing, less forgiving of poor recordings than my other speakers. The increase in detail is what I was hoping for so I'm well pleased thus far. Life is too short to bother with marginal recordings.

The upper half of the Hestia in the pic is just a test setup. I've been running one Manzanita for the base and the sound is very good. I'm leaning towards the GRS 15" for the base duties, perhaps in a flat baffle that is 24" wide at the base and 14" at the top with the taper on one side. 40" total height.

I'm pausing at this point while I dope out the bi amping issues. My preamp has two separate outputs, one being adjustable. Been looking at a 1875 chip amp for the top and my current class d amp for the base. Would handle the crossover at line level with filters as Mat has done recently. It would be simpler to just go with a plate sub amplifier and I may go that route if I get impatient.

Mat's work mating the MCM to the Vifa is really the heart of the system.

OB_Newbie · « **Reply #221 on:** 17 Nov 2014, 12:03 am »

Hey Moto!
Glad your enjoying the top of the Hestia! I heard the GRS are nice in OB! I went all MCM with dual 10's on the bottom for better detail and transient response (and a more narrow panel for my small room)... I like smaller drivers but most folks go with 15's or even 18's but I've found the dual 10's perform very well in my listening room... way more than I really need actually.

Cheers!
Rich

brad944911 · « **Reply #222 on:** 19 Nov 2014, 08:45 pm »

Guys, thanks for the advice!

I'm looking at OB Newbie's idea of dual 10's merely for SPL or something similar using Visaton WS25's, Typmphany horn tweet and a 12" sealed sub. I don't want to hijack this thread, but if you guys have any advice, I stuck up the question on a new post.

On that note, what are the crossover points for the Hestia? I'm crosseyed from scanning posts.

Can't wait to start this endeavor and FULLY join the OB club!

Thanks again!!
Brad

motosapien · « **Reply #223 on:** 20 Nov 2014, 03:34 pm »

Brad - The crossover between the mcm and vifa tweet is not really specified but the two LR2 filters work nicely. The bass driver starts coming on at 90hz where the mcm mid begins rolling off on the ob naturally. Pretty elegant use of the driver's curves all in all.

I'm sticking with the flat panel for asthetic reasons and may go with two 10" base drivers per side to raise the tweet to ear level and to keep the system from getting overly wide. I think the original design would satisfy most people but us diy folks can't seem to leave well enough alone. Have fun!!!

OB_Newbie · « **Reply #224 on:** 20 Nov 2014, 05:55 pm »

Quote from: matevana on 11 Jul 2012, 02:35 pm

The inductors are Jantzen 18 AWG air core and the Caps are Dayton Audio Polypropylene. I use the Dayton pre etched 2-way PC board number 260-130 which makes a nice finished product. I typically mount them on the baffle back with rubber washers.

L1 = 1.80 mh 18 AWG
C1 = 7.5 uf
L2 = 1.40 mh 18 AWG
C2 = 5.6 uf

Hey Brad,
Above is the X-over schematic for the original design. Honestly, I would stay with the MCM + Vifa top as is. Then run plat amps for the helper woofers. Its the helper woofers that allows you a little flexibility to add your own touch. A single 15... dual 10's or 12's... kinda depends on what you want for a baffle size and of course your own preferences for good bass characteristics such as speed, attack, extension, power handling.output, etc., etc.

Have fun with your build and check in with any questions. Can't wait to hear the progress.

Cheers!
Rich

motosapien · « **Reply #225 on:** 20 Nov 2014, 06:56 pm »

Brad - I noticed that 10" Visiton driver as being particularly siutable for ob. Price is right too at under $30. Perhaps you noticed on one of Matevena's newer designs that he is using line level filters to blend the bass into the midrange in place of a dedicated plate amp. This looks attractive to me because I've heard that relieving the mid driver of frequencies below say 100 hz or so improves the midrange response. Of course you need another amp to accomplish this but you could choose one that excells in mids and highs, like a 1875 chip amp for example.

newbie7800 · « **Reply #226 on:** 23 Nov 2014, 07:06 pm »

Slowest build in history update pic. Crossovers built for xt19 and mcm combo. Perhaps will be finished at Christmas....

Newbie

OB_Newbie · « **Reply #227 on:** 25 Nov 2014, 02:13 am »

Congrats Newbie! Let us know how you progress over the holidays... looking for forward to you getting some OB sound!!!

brad944911 · « **Reply #228 on:** 3 Dec 2014, 03:21 pm »

Well after much internal debate, I ordered up 4 MCM's and 2 of the Vifa XT19TD00-04 tweets with adjusted caps and coils to match the impedance. I plan on using one MCM with a plate for bass duties and one for mids with a sealed 12" JBL sub in a 2 ft3 enclosure for sub duties. I'll likely start the journey this week and will post pics for your amusement.
Thanks again for the guidance Matevana, moto and the newbies. Much appreciated

matevana · « **Reply #229 on:** 5 Dec 2014, 06:09 pm »

Niice! Looks like Christmas may come early this year?

piazzafatb · « **Reply #230 on:** 6 Dec 2014, 02:06 pm »

Receive cross parts from Newbie, thanks man

I would go with 2ea speaker - 12" MCM for LF.
Questions:

1- I have 1 Dayton 225 plate amp, would use initially for test to drive the 2 speaker. Would SQ suffer. ? How?
2- Want to go narrow. 16" wide baffle vs 18". Would be a significant difference between 16-18"?
3- Want to use 12-14ga bare solid cooper wire for LF driver back connection (just for looks) would this affect in some way?

OB_Newbie · « **Reply #231 on:** 7 Dec 2014, 01:21 am »

Quote from: piazzafatb on 6 Dec 2014, 02:06 pm

Receive cross parts from Newbie, thanks man

I would go with 2ea speaker - 12" MCM for LF.
Questions:

1- I have 1 Dayton 225 plate amp, would use initially for test to drive the 2 speaker. Would SQ suffer. ? How?
2- Want to go narrow. 16" wide baffle vs 18". Would be a significant difference between 16-18"?
3- Want to use 12-14ga bare solid cooper wire for LF driver back connection (just for looks) would this affect in some way?

Glad you got it Javi and ready for the build man!

1. Ed's original design had a single plate amp driving the helper woofer crossed at 90 Hz or so I think... I'd read the beginning of the thread. There isn't much stereo information in the very low frequencies so no problems if you keep the xover freq. low.
2. 16 is perfectly fine. The original design was slightly less than 16" if I remember right.
3. Solid copper sounds great to me. Fast and detailed but can sound thin... though my expirience was 18 awg (forgot to tell you than via PM) so not sure if 12-14 awg will sound thin and need doubling up.

Cheers!
Rich

matevana · « **Reply #232 on:** 7 Dec 2014, 03:51 pm »

Hey Piazza,

Rich was right on the money in his responses. If you're referring to solid conductor copper as opposed to stranded copper, you should be fine. It is somewhat less flexible (particularly in the thicker gauges) so it may not lay right across the floor but should sound fine. One of the better wires I've heard has been bare copper ground wire, encased in either vintage cotton or Teflon sheathing using air as the insulator. I would just stay away from copper coated aluminum wire, which can sound pretty awful IMO.

Ed

brad944911 · « **Reply #233 on:** 9 Dec 2014, 12:01 am »

Guys, a quick question here...this xover is a LR 2nd order, right. Shouldn't the tweeter be wired out of phase with the woofer? I'm sure it's been addressed but I couldn't find it. Thanks in advance, Brad

matevana · « **Reply #234 on:** 9 Dec 2014, 12:21 am »

Quote from: brad944911 on 9 Dec 2014, 12:01 am

Guys, a quick question here...this xover is a LR 2nd order, right. Shouldn't the tweeter be wired out of phase with the woofer? I'm sure it's been addressed but I couldn't find it. Thanks in advance, Brad

Brad. Generally speaking, in a purely 2nd order electrical circuit you would be correct. But you have to look at the summed acoustical response as well. If you build the crossover as spec'd but try reverse polarity, you would likely hear that they do not sum properly. I remember a loss of coherence with cymbals, etc. when the tweeter was reversed. Very few topologies work-out to be textbook and it pays to try them both ways. Go with the one that measures (sounds) best.

brad944911 · « **Reply #235 on:** 9 Dec 2014, 01:21 am »

Ed, thanks so much for that! I read thru your early design notes and thought I remembered you saying something about not using standard wiring. Perfect!! I have all the baffles cut and need some finish work done. Pretty amped!

newbie7800 · « **Reply #236 on:** 9 Dec 2014, 12:00 pm »

One more step guys. Even though I only have a plywood baffle I wanted to use this project to learn some skills. So I spent Saturday (took a good few hours) to do the recess for all drivers, not just the tweeters. I used a rabbet bit but unfortunately only had 12.7mm as the maximum so had to do some sanding to fit the MCM. I am about 1mm off on all the drivers after a test fit. I was wondering, how does everyone screw in the drivers. I have the baffles balanced between two cardboard boxed and I am dropping in the drivers through the holes but it is not easy, kind of need 4 hands to do this properly.

A question on the RCA plug filter used for the bass driver - where do I put these exactly in my wiring. Is it for the preamplifier out towards the plate amp??? This would act as a filter from the preamp to the plateamp. Assuming this is correct?

Thanks for all your help. Almost in touching distance to getting this project finished!!!

Newbie

matevana · « **Reply #237 on:** 9 Dec 2014, 12:40 pm »

Quote from: brad944911 on 9 Dec 2014, 01:21 am

Ed, thanks so much for that! I read thru your early design notes and thought I remembered you saying something about not using standard wiring. Perfect!! I have all the baffles cut and need some finish work done. Pretty amped!

That looks great Brad! You have to let us know your thoughts when you begin testing.

matevana · « **Reply #238 on:** 9 Dec 2014, 12:48 pm »

Quote from: newbie7800 on 9 Dec 2014, 12:00 pm

A question on the RCA plug filter used for the bass driver - where do I put these exactly in my wiring. Is it for the preamplifier out towards the plate amp??? This would act as a filter from the preamp to the plateamp. Assuming this is correct?

Newbie

If you are building one of the original Hestias and are using a plate amp with a built-in crossover, you will not need to use an F-Mod (passive inline crossover). If your plate amp doesn't have an on board crossover, you can attach the F-mod directly to the input on the plate amp.

newbie7800 · « **Reply #239 on:** 9 Dec 2014, 01:59 pm »

Matevana

Thanks as ever...yes building the original hestia as of November 2012

Whoops I did not realise the fmod was for another hestia build...I have the original plate amp you recommended and which sjhomey also got. It has an active cross over. So I have no purpose for the fmod.

I am 1 day away from completing the build.thanks again for all your support.

Newbie