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

matevana · « **Reply #40 on:** 21 Jul 2012, 12:43 am »

Quote from: zipidachimp on 20 Jul 2012, 09:29 pm

my knowledge of plate amps is nil. more research required. thanks.
can you supply a finished wiring diagram, including the receiver, or point me in that direction? thanks again.

Take a look at this link for a nice plate amp at a reasonable cost. Today PE is running a 'deal of the day' special for $99.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=301-510

I simply run the left/right line out from my integrated amplifier (receiver) to the left/right input of the plate amp. The plate amp comes on automatically when it senses an input signal, and turns off about 15 minutes after the last signal is presented. With this model you have control over gain (level match), crossover (frequency match) as well as a full variable phase control (0 through 180 degrees) to more seamlessly integrate the phase/delay relationship between the plate amp and main amp. It also uses a class D switching power supply mode, which essentially produces lots of power with little heat, in a small package.

Poultrygeist · « **Reply #41 on:** 21 Jul 2012, 01:45 am »

I use two of these Daytons amps which have built -in crossovers to drive my H-frame Alphas. They can be daisy chained ( mono or stereo ) and each has a volume control. I bought them when they were on sale for $120 each. They were formerly sold by Emotiva.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-812&FTR=apa%20amplifier

zipidachimp · « **Reply #42 on:** 21 Jul 2012, 02:21 am »

Hmmmmm. having a few thoughts.......I own but no longer use a sony subwoofer. If I remove that dual voice coil speaker, can I wire the rest in to my existing 3-way setup? or is that loony? it has controls for cut-off freq, phase and level. thanks for any help, and sorry if thread appears hi-jacked.

matevana · « **Reply #43 on:** 21 Jul 2012, 12:35 pm »

Quote from: Poultrygeist on 21 Jul 2012, 01:45 am

I use two of these Daytons amps which have built -in crossovers to drive my H-frame Alphas. They can be daisy chained ( mono or stereo ) and each has a volume control. I bought them when they were on sale for $120 each. They were formerly sold by Emotiva.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-812&FTR=apa%20amplifier

Yeah, I like those. Very useful in a lot of applications and they have nice 18dB/oct low pass filters.

matevana · « **Reply #44 on:** 21 Jul 2012, 12:37 pm »

Quote from: zipidachimp on 21 Jul 2012, 02:21 am

Hmmmmm. having a few thoughts.......I own but no longer use a sony subwoofer. If I remove that dual voice coil speaker, can I wire the rest in to my existing 3-way setup? or is that loony? it has controls for cut-off freq, phase and level. thanks for any help, and sorry if thread appears hi-jacked.

You can try, and if you're not happy, go out and buy a different plate amp.

matevana · « **Reply #45 on:** 29 Jul 2012, 01:56 pm »

Some experimentation on low frequency driver integration and drive levels:

LF Driver height:

I have definitely found that placing the woofer as close to the floor as possible is an advantage when dealing with boundary effects and floor bounce. As demonstrated decades ago by the Allison model one speaker, its advantageous to keep these drivers low. This helps push any resulting negative cancellation from bounce above the critical 100 to 300 Hz range, which plague many speaker designs. Experiencing "suck-out" in this range can greatly reduce realism. If you do have residual bounce effects from your room, it's best to push them above this range.

LF Crossover Settings:

While every design is different, I personally try to keep signals above 90Hz away from the LF driver. Most of my designs use a single plate amp for LF signals which sum the front left & right output into a monaural signal. If you cross at higher frequencies you are likely to start experiencing a degradation of the stereo image, as the location of this information starts to become more detectable by the human ear.

LFE Output:

I try never to use the LFE output from a receiver. It's important to have the flexibility from a continuously variable crossover when integrating drivers. The course settings from most receivers will simply not cut it. I have found that differences as small as 10Hz can make a difference when attempting to seamlessly integrate drivers.

Pre Out or Subwoofer Line Out:

Oddly enough, it seems that many amps used to drive LF speakers are not driven sufficiently by the line out coming from the receiver. The level is oftentimes too low as many receiver designs err on the side of caution in determining output level with a host of possible manufacturers equipment (less of a customer support issue when the signal is set too low than too high).

It's amazing to hear the sound quality difference between signals from a receiver's line out vs. splitting the source and sending that directly to your LF plate amp. If you'd like to try an inexpensive test, get an RCA splitter like the one pictured below (y-cables are not always the best choice here) and compare that to the signal quality from your receiver's line out. In most cases the signal level will be a better match and will drive the amp with more authority, and slightly lower distortion (and heat) due to the ability to now run the amp at lower levels. You will need to either preset the plate amps level or use the volume control on your source unit (CD player, if equipped) as a master volume control.

Poultrygeist · « **Reply #46 on:** 29 Jul 2012, 02:23 pm »

I also like splitting the source.

In my case I take the analogue out put from the CDP and send it to my integrated tube amp which drives the full range mains. Then I take the digital output from the same CDP and send it to a Denon AVR which drives the bass woofers through a 80hz low pass. I think I paid $35 for the non-HDMI AVR and it has plenty of power for my bass woofers in two channel mode and is way cheaper than plate amps. It's also nice to have a remote to control the bass output.

matevana · « **Reply #47 on:** 30 Jul 2012, 11:48 am »

Quote from: Poultrygeist on 29 Jul 2012, 02:23 pm

I also like splitting the source.

In my case I take the analogue out put from the CDP and send it to my integrated tube amp which drives the full range mains. Then I take the digital output from the same CDP and send it to a Denon AVR which drives the bass woofers through a 80hz low pass.

Great point Poultry using the digital output as a 2nd source for your AVR. This wont work for plate amps obviously, but for anyone like yourself who uses an AVR as their LF amp, you will certainly benefit from this as well. It must also be nice to have arm chair control of the sub's levels! What are you using for an integrated amp?

Poultrygeist · « **Reply #48 on:** 30 Jul 2012, 02:18 pm »

I have two integrated amps, a Miniwatt S1 and a Dared 2a3c. I use these interchangeably to drive the main OB full rangers while using an AV receiver to drive the bass Alphas. You can't beat garage sale AV receivers for cheap watts and since HDMI came into vogue there are tons of cast off non-HDMI AVRs on the used market.

On another set of OB Beta/Alpha H-frames I use a Bottlehead 2a3 amp/preamp on the Betas/tweeters. In that system I drive the Alphas with two Dayton APA 150's ( with built-in crossovers ) but I can't say the Alphas perform any better than with an AV receiver and two low pass filters.

matevana · « **Reply #49 on:** 30 Jul 2012, 09:34 pm »

I wish I could hear your system. The only real pitfall about having OB as a hobby, is their lack of popularity and the associated difficulty in comparing designs in person

Poultrygeist · « **Reply #50 on:** 30 Jul 2012, 11:31 pm »

And I yours.

While there's little opportunity to hear other's systems it's safe to say that most of us who have experienced OB are convinced of it's goodness. It has spoiled me to no end.

Squidspeak · « **Reply #51 on:** 4 Aug 2012, 02:38 am »

Matevana, do you have a complete build thread and x-over diag. for this. I think this
might be my first OB project, I already have the tweeters and like everything else I
have read in the thread it seems to be incredible bang for buck.

matevana · « **Reply #52 on:** 5 Aug 2012, 12:32 pm »

Quote from: Squidspeak on 4 Aug 2012, 02:38 am

Matevana, do you have a complete build thread and x-over diag. for this. I think this
might be my first OB project, I already have the tweeters and like everything else I
have read in the thread it seems to be incredible bang for buck.

Hi Squidspeak,

Post #13 shows the capacitor and inductor values, the wiring schematic and the finished crossover. It uses a very traditional Linkwitz-Riley 2nd order electrical wiring scheme. You can even buy pre etched boards to make the finished design look a bit neater.

While the LR-2 wiring scheme is standard, the piece that's a bit unusual lies in the component value selection. Not only is there no significant overlap between the tweeter and midbass, but by design, there is a small deficit between the two, producing a very slight dip in the frequency range normally associated with loudspeaker "shout". This helps give the Hestia it's characteristic sound, and IMO makes for hours of non-fatiguing listening possible. Unlike some large woofer/small FR driver designs, the midrange is NOT lacking and comes across as very natural with the proper weight and authority.

I had the luxury of being able to design-on-the-fly using a 3 way active crossover at the same 12dB slope, which was a great help in listening to driver interaction and understanding the outer limits of each driver. Once the x/o points and levels were scrutinized using the active set-up, I swapped in the passive components and remeasured (and swapped components again) until the new curve more or less matched the original. My take-away from this exercise was that while many drivers operate properly within their stated response range, huge performance gains can be derived by avoiding the the fringes of this range.

Tyson · « **Reply #53 on:** 5 Aug 2012, 04:09 pm »

Just curious - why did you switch to passive? Why not just keep the active crossover in place?

Squidspeak · « **Reply #54 on:** 5 Aug 2012, 04:52 pm »

Matevana, thank's for the response. This will be my first OB project and
what sold me was I bought those tweeters from P/E when on closeout
and they would not work in my project, so I've been trying to find a use
or home for them. Also wanted to try a OB design but wasn't sure which
one. Anyway do you feel this design would benefit from going with stereo
on the bottom(2 plate amp's)?

matevana · « **Reply #55 on:** 5 Aug 2012, 06:53 pm »

Quote from: Tyson on 5 Aug 2012, 04:09 pm

Just curious - why did you switch to passive? Why not just keep the active crossover in place?

The design goals for the project included: low cost; all inclusive design; easily reproducible results. An all active 3-way design would likely be out of the price range for many who might otherwise be tempted to build this project. It would also be subject to improper adjustment for those not familiar with the desired outcome.

As it stands, the Hestia will sound phenomenal with less than $200 in amplification, namely a small tripath amp for the mids/highs and a decent plate amplifier for the lows. It is also sensitive enough to be run with small integrated amps, SETs, etc. That being said, anyone who wishes to convert the project to three amps and a 3-way x/o will likely see increases in performance; just not sure it's the best bang-for-the-buck when the project title reads "ambitious low cost 3-way OB design".

One more comment regarding sound quality with active designs. I have used crossovers from DBX and Ashly with good results. These were typically good quality analog designs with fairly high signal-to-noise characteristics and dynamic range. I have also experimented with digital x/o's from Berringer and MiniDSP. While many might disagree, I typically experienced a degradation in overall SQ with these digital versions, albeit the adjustment was very precise.

Squidspeak · « **Reply #56 on:** 8 Aug 2012, 01:23 am »

Matavena, I saw in another thread you suggested the OP just use the passive
top with an existing sub. Would there be much to gain "budget aside" by going
with larger bass drivers and 2 plate amps in stereo?

matevana · « **Reply #57 on:** 8 Aug 2012, 02:33 am »

I personally like the sound of OB bass (for music). The person in the other thread had an existing vented box he wanted to use in conjunction with an OB top. In his case, the Hestia minus the the LF driver would be fairly easy to integrate.

Personally I wouldn't change anything about the design. It is very balanced at moderate SPL's and the bass is not lacking. I would use a decent plate amp as lesser amps might have trouble keeping up. With the x/o set at around 90 Hz, very little would be gained by using a 2nd plate amp and running the sides in stereo. Certainly something you could try later as an upgrade, but I believe you will be very happy with mono bass as intended.

For amps I highly recommend either the Yung 300W with boost @ 30Hz, the O-Audio Bash 300 or the Dayton Bash 300, in that order. Other amps that I had on hand did not sound nearly as good. When they go on sale, you can get any of the three for right around $100. I have the Yung driving my Hestia right now, and it runs cool even after many hours of use. For the top I alternate between a NAD integrated amp and a Topping Tripath chip amp, and still cant decide which one I prefer. Both sound excellent with the design.

Squidspeak · « **Reply #58 on:** 8 Aug 2012, 05:34 pm »

Quote from: matevana on 8 Aug 2012, 02:33 am

I personally like the sound of OB bass (for music). The person in the other thread had an existing vented box he wanted to use in conjunction with an OB top. In his case, the Hestia minus the the LF driver would be fairly easy to integrate.

Personally I wouldn't change anything about the design. It is very balanced at moderate SPL's and the bass is not lacking. I would use a decent plate amp as lesser amps might have trouble keeping up. With the x/o set at around 90 Hz, very little would be gained by using a 2nd plate amp and running the sides in stereo. Certainly something you could try later as an upgrade, but I believe you will be very happy with mono bass as intended.

For amps I highly recommend either the Yung 300W with boost @ 30Hz, the O-Audio Bash 300 or the Dayton Bash 300, in that order. Other amps that I had on hand did not sound nearly as good. When they go on sale, you can get any of the three for right around $100. I have the Yung driving my Hestia right now, and it runs cool even after many hours of use. For the top I alternate between a NAD integrated amp and a Topping Tripath chip amp, and still cant decide which one I prefer. Both sound excellent with the design.

Matavena, again thanks for the response/opinion. I also want to keep it OB
bass, but I would like to use the Dayton PA310 for the bass duties and either go with
the Yung 500W mono or 2 300w stereo on the bottom. Is there any issues with the
X-over point going mono with 2 8ohms vs. stereo with individual 8ohm drivers. I just
want to kick it up a notch and still think it would be a budget build. Let me know your
opinion. I'll call it "Hestia Grand" LOL Thanks SQUIDSPEAK

matevana · « **Reply #59 on:** 8 Aug 2012, 07:23 pm »

Quote from: Squidspeak on 8 Aug 2012, 05:34 pm

Matavena, again thanks for the response/opinion. I also want to keep it OB
bass, but I would like to use the Dayton PA310 for the bass duties and either go with
the Yung 500W mono or 2 300w stereo on the bottom. Is there any issues with the
X-over point going mono with 2 8ohms vs. stereo with individual 8ohm drivers. I just
want to kick it up a notch and still think it would be a budget build. Let me know your
opinion. I'll call it "Hestia Grand" LOL Thanks SQUIDSPEAK

Hey Squid,

The Hestia Grand? I think she will like that!

No problems with the plate amps concerning crossover points, as the active x/o is independent of the impedance load the amp sees. What's not independent however is the amount of power the amp will produce at either 4 or 8 ohms. A 500 watt amp may produce 500 watts @ 4 ohms but may only produce a little over 250 watts @ 8 ohms. Therefore two separate amps at 8 ohms per side, may not "see" much more power than two 8 ohm drivers wired in parallel to one amp (4 ohms total), if that makes any sense?

You may want to give some thought to the baffle dimensions with the PA310. The PA310 (a 12" bass driver) is larger and will require more real estate to address dipole cancellation. The 15" wide baffle may not work in your case... you may need to look at an 18-20" width instead which may also negatively impact the speakers imagining characteristics up top. The 12" drivers Fs is only 2 Hz less than the 10", so you will likely not notice any deeper bass, although it will move a larger slug of air. It also has a higher MMS rating which will likely result in more baffle noise (vibration).

I would encourage you to experiment with the design. Just wanted to point out a few things so you don't wind up paying more and getting less.