Built up the crossovers, installed, and finished wiring them up. Just using zip cord right now to make sure everything works. I used a terminal strip as a temporary thing. I bought a few extra resistors to experiment with the tone. When all is done I will solder point to point. I stained and then finished with Polycrylic. Installed the speakers. I guess they turned out ok. I laughed at myself when I tried to drive them with the Tubelab SSE I built. I ended gabbing a chip amp I build't about two years ago. It puts out about 65 watts. I thought I had a problem with a crossover after the right channel dropped out after about five minutes. Traced it to a crappy interconnect on the negative side. A 5 cent wire nut fixed the problem. I then listened trouble free for about three hours.
Attachments
Well John, it looks like we about 1/2 agree.From my point of view, it pretty much all comes out the same. True, with the active filter you don't have the big inductive load, but most amps don't seem to mind it.
OK, then were does the power go? You say it's not dissipated by the crossover and the current and voltage at the driver are the same. Where is the extra power dissipated?
What I said was that efficiency is probably not a good usage here. There is a difference between the power dissapated in the VC and the reactive power the amp must supply. Energy is stored in caps and inductors, and released. But the energy needed to charge the reactive element must come form somewhere and that is the amp, placing greater current and voltage demands aon the amp than an active eq does.
Anyway, look at my page on hybrid design and you might get an idea of why active eq yeidls improved headroom:
Hybrid Design
The argument applies to baffle step in box spakers as well as dipole eq.
With EQ ahead of the poweramp (active or not), the voltage swing at the output of the power amp would in this case (OB) only be high for the lowest frequencies. If a wideband signal is sent through the poweramp, although the power dissipation may not be substantially different, the total voltage swing would be a bit higher, due to the full amplitude presence of the higher frequency energies. Most poweramps are more limited by voltage swing than power dissipation, so I would expect better headroom in the poweramp when the EQ is ahead of the poweramp.
A slightly different subject is the reactive nature of the load with the passive EQ (12 - 20mH inductor). High feedback amplifiers sometimes have tantrums when they drive highly reactive loads (the reactive load shifts in time ("phase-shift") the feedback signal in the amp circuit). Most speakers are relatively resistive in their intended passband, but if they've got 15mH of coil in series with them, some high feedback poweramps might get mad.
The other thing that one could argue is that with EQ ahead of the poweramp, the amps output Z as seen by the driver is very controlling (usually a good thing), since the source impedance of a high feedback amp is measured in milliohms across frequency. With the giant inductor in between the amp and the speaker, damping of the speaker by the amplifier rolls off dramatically as you go up in frequency; as soon as the frequency response is rolled off by the inductor, which starts in at about 60HZ in this case.
To be fair, low damping doesn't necessarily sound bad. The high end low feedback tube poweramps have low damping (1 to 8 ohm output impedance), and many people like that sound (not me, I like tight accurate bass).
I'd be a bit concerned about "cavity effect" on the rear radiation with side boards that are 4 inches deep. I limited mine to 3 inch total, 1.5 inch extended beyond the back side of the 1.5 inch thick front baffle board, and put a 45 degree corner brace made of oak (high density and very stiff) in there to help "waveguide" the acoustic energy out into the room with minimal frequency selective acoustic reactance.
Scroll down about an inch to see a photo of what I just described.
http://www.spiritone.com/~rob_369/audio/AuriumWaveguide2010.htm
A slightly different subject is the reactive nature of the load with the passive EQ (12 - 20mH inductor). High feedback amplifiers sometimes have tantrums when they drive highly reactive loads (the reactive load shifts in time ("phase-shift") the feedback signal in the amp circuit). Most speakers are relatively resistive in their intended passband, but if they've got 15mH of coil in series with them, some high feedback poweramps might get mad.
The other thing that one could argue is that with EQ ahead of the poweramp, the amps output Z as seen by the driver is very controlling (usually a good thing), since the source impedance of a high feedback amp is measured in milliohms across frequency. With the giant inductor in between the amp and the speaker, damping of the speaker by the amplifier rolls off dramatically as you go up in frequency; as soon as the frequency response is rolled off by the inductor, which starts in at about 60HZ in this case.
To be fair, low damping doesn't necessarily sound bad. The high end low feedback tube poweramps have low damping (1 to 8 ohm output impedance), and many people like that sound (not me, I like tight accurate bass).
I'd be a bit concerned about "cavity effect" on the rear radiation with side boards that are 4 inches deep. I limited mine to 3 inch total, 1.5 inch extended beyond the back side of the 1.5 inch thick front baffle board, and put a 45 degree corner brace made of oak (high density and very stiff) in there to help "waveguide" the acoustic energy out into the room with minimal frequency selective acoustic reactance.
Scroll down about an inch to see a photo of what I just described.
http://www.spiritone.com/~rob_369/audio/AuriumWaveguide2010.htm
Exactly.
Much is often made of this but electromotive damping really is only significant around the driver's resonance. Above and below resonance damping the decreases quickly. Above resonance it's mass controlled. Below it's compliance controlled.
Looking good!
Shortwave, good to see you have completed the project. Looking forward to your assesment after break in.
That takes a few hours and both the Vifa and the Peerless sweeten up considerably with time.
Pano's power requirement comments are right on. You will find the Manzanita power hungry for sure. It is very revealing when it comes to amplifiers. Both power wise and sonically.
Can you tell us a bit about your listening room and what your musical preferences are?
I have been doing a lot of measurements on the Manzinita the last few days. Comparing it to several different designs. At 36 - 40" from the rear wall in a medium to large size room it measures very flat. Measuring at 8-12 feet on axis. They sound best to me with the Vifa mid-tweeter about 38- 42" off the floor with a slight tow in torward the listening position.
Do you have any measement software? If so, would like to know how your pair measure in your listening environment.
Thanks again for taking the leap and sharing your construction process - efforts.
Shortwave, good to see you have completed the project. Looking forward to your assesment after break in.
That takes a few hours and both the Vifa and the Peerless sweeten up considerably with time.
Pano's power requirement comments are right on. You will find the Manzanita power hungry for sure. It is very revealing when it comes to amplifiers. Both power wise and sonically.
Can you tell us a bit about your listening room and what your musical preferences are?
I have been doing a lot of measurements on the Manzinita the last few days. Comparing it to several different designs. At 36 - 40" from the rear wall in a medium to large size room it measures very flat. Measuring at 8-12 feet on axis. They sound best to me with the Vifa mid-tweeter about 38- 42" off the floor with a slight tow in torward the listening position.
Do you have any measement software? If so, would like to know how your pair measure in your listening environment.
Thanks again for taking the leap and sharing your construction process - efforts.
John,
First off I have to say that I’m very pleased with your design. I have a total of about six hours of listening time on them and think their great.
A note on my gear I’m using. It’s not high end. I’m trying to get there. My CD player is a 12 year old JVC. I’m using a 386 based chip amp I made. I initially listened to the OB’s in my unused main finished room in my basement (12 x30) with a cement floor. Nothing serious, it was just to see if everything was OK and I just moved my chair around and angled the OB’s just to see while having a beverage or two. Big sound to say the least! An increase in clarity and resolution I was very happy to hear.
Tonight I had them in a 12 x 10 carpeted room. I had them on 14” stands (all I got until I can make some taller ones) and sat down on the floor to align with the middle of the baffle. I wanted to see what some of my FLAC files sounded like (digital source through a DAC). I listen to most anything. I guess I prefer rock. Tonight it was a one of my favorite boots, a UFO live show from 93’, followed by another boot from Van Halen 75’ and 77’. Then some acoustic Beatles from 69’ and 70’ follow by their famous or infamous rooftop concert. What I noticed is that both speakers seem sharing the load so to speak. Again more clarity and resolution then I have heard before. I wish I had more solid information for you but I don’t have any type of measuring gear. I did measure the resistance through each side at 6.5 and 6.6 ohms. Does that sound right?
For the cost, time and effort to build these, and as a newbie to speaker making, I would not hesitate to recommend building a pair.
First off I have to say that I’m very pleased with your design. I have a total of about six hours of listening time on them and think their great.
A note on my gear I’m using. It’s not high end. I’m trying to get there. My CD player is a 12 year old JVC. I’m using a 386 based chip amp I made. I initially listened to the OB’s in my unused main finished room in my basement (12 x30) with a cement floor. Nothing serious, it was just to see if everything was OK and I just moved my chair around and angled the OB’s just to see while having a beverage or two. Big sound to say the least! An increase in clarity and resolution I was very happy to hear.
Tonight I had them in a 12 x 10 carpeted room. I had them on 14” stands (all I got until I can make some taller ones) and sat down on the floor to align with the middle of the baffle. I wanted to see what some of my FLAC files sounded like (digital source through a DAC). I listen to most anything. I guess I prefer rock. Tonight it was a one of my favorite boots, a UFO live show from 93’, followed by another boot from Van Halen 75’ and 77’. Then some acoustic Beatles from 69’ and 70’ follow by their famous or infamous rooftop concert. What I noticed is that both speakers seem sharing the load so to speak. Again more clarity and resolution then I have heard before. I wish I had more solid information for you but I don’t have any type of measuring gear. I did measure the resistance through each side at 6.5 and 6.6 ohms. Does that sound right?
For the cost, time and effort to build these, and as a newbie to speaker making, I would not hesitate to recommend building a pair.
Thanks for the feed back!
Shortwave...
Glad you are pleased with your new babies! Your comments are typical from those who have listened to them. One thing nice about a small OB is it sounds similar in many different environments. Sounds the best outside actually!
Thanks for providing your listen room info and first impressions. And of course your positive concluding remark. And 6-8 ohms is what you should see.
Trust the Manzanita's will provide you years of enjoyment and if anything does happen to go bad, you know how to fix-em!! That means nothing will go bad!
Shortwave...
Glad you are pleased with your new babies! Your comments are typical from those who have listened to them. One thing nice about a small OB is it sounds similar in many different environments. Sounds the best outside actually!
Thanks for providing your listen room info and first impressions. And of course your positive concluding remark. And 6-8 ohms is what you should see.
Trust the Manzanita's will provide you years of enjoyment and if anything does happen to go bad, you know how to fix-em!! That means nothing will go bad!
I cut the Vifa at 3 1/16 inch. It fit perfect.
I cut the Peerless at 11 inch. The hole might be 1/16 too big for a snug fit but the gasket on the speaker fits perfect onto the plywood surface. When you get the Peerless you'll see the gasket and where the speakers mounts. Anyway, I cut hole in thin scrape to verify fit before I touched the finish plywood. Good luck.
Yes, I would agree especially flush mounting the drivers. But, since these are front mount and several have made these, I thought they could give the dimensions they used.
Thanks shortwave!
Got the Manzanitas running. In a word, WOW!
These are in a small room - 12' x 15', so far 30" out from the rear wall. Bass is very nice, moderate level with a stock Lepai (don't laugh). I'm going to try it with one of my Sure's.
JB, thanks for this design. I know you spent a lot of time on this and the results show. I always wanted to try an OB but they were always too big. This one is just right.
These are in a small room - 12' x 15', so far 30" out from the rear wall. Bass is very nice, moderate level with a stock Lepai (don't laugh). I'm going to try it with one of my Sure's.
JB, thanks for this design. I know you spent a lot of time on this and the results show. I always wanted to try an OB but they were always too big. This one is just right.