[LostInPA]

There is plenty of acclaim for the Crystal 10 driver.   I have chosen to work with the smaller and barely noticed sibling, the Fast 8 driver.   I started with the measured parameters as shown on the web page.    The formulas that I used need also the parameter for Xmax, which was not given.   An email to Lii Audio produced a very rapid response for this, which is 6 mm.   I chose to make a sealed box of approximately 2.2 cubic feet net volume, using 3/4 inch MDF, of a somewhat old school approach with a wide front.   Overall dimensions are 18 inches wide, 24 inches tall, and 12 inches deep.  The only internal bracing is 5 pieces of 1 1/4 inch diameter dowel, positioned with glued in 1/4 inch diameter fluted dowel pins at the ends, all glued to blind drilled holes in both the front and the back walls.   I used Sonic Barrier Acoustic Sound Damping Foam, 1/2 inch thick at the top, and 1 inch thick at the bottom and two sides;  1/8 inch thick wool felt at the back;  1/64 inch thick Cotton Flannel Felt to wrap the five braces .

The formulas produced the following numbers, which I can consider only as reasonable approximations as I have no way to measure the actual results:
Low frequency response has a gradual rise to of less than 1 dB at 110 HZ, after which there is a decrease to -3 dB at 57 Hz, -6 dB at 46 Hz, and -12 dB at 33 Hz.

I have 50 hours on these so far.   Soundstage started as excellent, and has improved.   Tonality and dynamics started as very good, and are now approaching excellent.  The photograph shows the speakers in a temporary setup for burn-in purposes.   I only occasionally have a desire for a bit more bass.   The speakers will eventually go in to a smaller room, on taller stands, and with a placement close to corners; I expect ultimate low frequency response to be less of an issue here.

This was a fun project, and I very much enjoy the listening.

   

[wynnytsky]

Nice job Steve.  Interesting you went sealed when most people open up somewhere.  Otherwise it checks all the boxes for what I want in a 2nd system, and at 5% the cost of the Nenuphar Mini Monitor.  I've got this 1/4" 95% wool felt laying around -- would be a waste to NOT build a set!

[oskar]

Thanks for posting that. Iv'e had my eye on those.

[HiGHFLYiN9]

Very nice work Steve, it's a great looking set up. Looking forward to further impressions.

[versus rider]

They look cute

[uncola]

nice job!

[FullRangeMan]

Nice speaker, what are the box internal volume?

[LostInPA]

Clarification:  approximate internal volume is 2.26 cubic feet gross/2.17 cubic feet net.

The speakers have more than 200 hours on them now.   There were minimal changes over the past 80 hours.   Tonality and imaging remain excellent.   A no-fatigue sound.   The speakers are now on taller stands, in a smaller room, placed at 45 degrees  in the corners of a long wall.   A bit more perceived bass in this location.   I could position myself to include only one of the speakers in this photo.   Probable future updates will be about amplifiers used, and possibly also addition of a pair of powered subs.   Stay tuned.

[FullRangeMan]

Thanks, seems 61L.

[LostInPA]

Those of you who have played around with audio for any length of time know this to be true: equipment accumulates.  Some of this accumulation will now be unboxed for experimentation. 

These speakers were, from the start, powered from a Parasound Zamp v.3, at 45 wpc. within the rating of the drivers, giving a clean and fast sound.  The overall performance  of the system was obviously limited by the limitations of the Fast 8 in a sealed box.   The first addition was a pair of Gallo Classico CLS-10 powered subs.  The Zamp has jacks for signal passthrough, and this is where I connected the subs.  The Fast 8 still run full range, and the subs are set for a 110 Hz crossover frequency.    On the plus side, this filled out the frequency spectrum nicely.   On the minus side, integration was not the best, as these subs were not up to the speed of the mains.   Next out of it's box was an Ashly  XR-1001 stereo 2-way analog crossover.   I could now use balanced interconnects out from the DAC to this crossover.  XLR to RCA adapters at the outputs were used for the interconnects from the crossover to the Zamp and to the powered subs.   Crossover frequency was set to 110 Hz, and the sub amps were set to bypass the internal networks.   This is now much better.   The Fast 8 no longer see very low frequencies, and the remaining range is more clear and effortless.   There remains the problem of the synergy of the mains and the subs.   

One further thing to try, because it was available.   The Zamp was taken out and replaced with an FX Audio Tube P1 amplifier, at 2 or 2.5 wpc, depending on which blurb you read.   This was originally acquired for use as a headphone amplifier.   There is more than 720 mW available at the headphone jack.   I added 4 ohm/5 watt resistors at the speaker binding posts for safety.   Sound was adequate but not particularly interesting with the stock tubes.   The input 6J1 tubes were replaced with RTC 5654, and the output 6P1 tubes were replaced with Winged "C" 6P1P-EB.   This gave a cleaner sound, and with more body.   This 2+ watts is sufficient to drive the Fast 8 above 110Hz and in this small room.   There is now a better integration of the mains and the subs.

I presently have no need or desire to make any other changes.   The sound is very satisfying.   The only downside is that it is very unforgiving of poorly recorded material.   However...I have out on loan a PodWatt amp from OddWatt Audio  http://www.oddwattaudio.com/owpoddwatt.html   The present health emergency will keep this out of my reach for a while.

[uncola]

this might be a dumb question.. but on this frequency response chart..  how do I read it, is the red line on axis and the blue line off axis?  so off axis, the volume goes way down?
EDIT:  nevermind my smart friend told me the blue line is impedance

[LostInPA]

I have gone back to the Parasound Zamp v.3.   This 45 watts of PP bipolar transistors is a much more substantial sound than the 2 watts of SE tubes.   I can now turn up the volume, and not run out of headroom.   Perhaps the speakers needed more hours to break in?   

[Woodsage]

I’m running these in a narrow open baffle with active bass augmentation and have had a hell of a time integrating the bass properly.

I finally broke out the test CD and did some frequency response test. They drop like a rock at around 200 Hz in my open baffles. I was initially running the bass at around 110 Hz but now have it up closer to 200 with the gain adjusted down quite a bit and it sounds much better.

They also seem to drop off quite a bit once you get up over 10-12 KHz at least by my crude measuring. Doesn’t matter to me because I can’t hear anything above 12 KHz anyway.

Mike

[Russell Dawkins]

What does it look like between 200 and 10k?

[Woodsage]

What does it look like between 200 and 10k?

Pretty flat as I recall.

[FullRangeMan]

I’m running these in a narrow open baffle with active bass augmentation and have had a hell of a time integrating the bass properly.

I finally broke out the test CD and did some frequency response test. They drop like a rock at around 200 Hz in my open baffles. I was initially running the bass at around 110 Hz but now have it up closer to 200 with the gain adjusted down quite a bit and it sounds much better.

They also seem to drop off quite a bit once you get up over 10-12 KHz at least by my crude measuring. Doesn’t matter to me because I can’t hear anything above 12 KHz anyway.

Mike

I’m running these in a narrow open baffle with active bass augmentation and have had a hell of a time integrating the bass properly.
This is a 8'' FR, but 8'' woofers start attenuate 6dB per octave at 120Hz, you could use a 15'' woofer instead.
They also seem to drop off quite a bit once you get up over 10-12 KHz at least by my crude measuring.
Do you mean say the treble is bad?

[Woodsage]

I’m running these in a narrow open baffle with active bass augmentation and have had a hell of a time integrating the bass properly.
This is a 8'' FR, but 8'' woofers start attenuate 6dB per octave at 120Hz, you could use a 15'' woofer instead.
They also seem to drop off quite a bit once you get up over 10-12 KHz at least by my crude measuring.
Do you mean say the treble is bad?

My preference is for 15” woofers however the existing baffle is too narrow for that. I am running four 10” woofers per side instead.

No I am not saying the high end is bad; I was surprised at the drop off when I measured it. I find the high end very pleasing and detailed but, again, I can’t hear sh@t above 12 KHz. Not unusual for someone of advanced age like myself.

All in all I really like the drivers but was surprised how high they rolled off. Very similar to my Oris 200 horns with AER drivers. You turn off the bass and it’s amazing how little volume is coming from the full range driver.

Mike

 

[uncola]

hi woodsage, what 10" drivers are you using?  I was looking at the Faital PRO 10FE200

[Russell Dawkins]

All in all I really like the drivers but was surprised how high they rolled off. Very similar to my Oris 200 horns with AER drivers. You turn off the bass and it’s amazing how little volume is coming from the full range driver.

Mike

If you are saying the Fast 8's are in any way comparable in tone to the Oris Horn with AER drivers, I'm very impressed. That would seem to make the Fast 8 a bargain at the current price.

Incidentally, this is a convenient substitute for a test CD for automated frequency sweeps, if you can hook up your computer to your stereo system:
http://onlinetonegenerator.com/frequency-sweep-generator.html

and this lets you sweep manually, at your speed:
https://www.szynalski.com/tone-generator/

[Woodsage]

hi woodsage, what 10" drivers are you using?  I was looking at the Faital PRO 10FE200

I am using Hawthorne Audio Augies which hit pretty hard into the low 30's. The Faitals look nice but don't look like they are going to go very low. That being said I would bet they sound better up above say 150 Hz than the Augies.

If you are saying the Fast 8's are in any way comparable in tone to the Oris Horn with AER drivers, I'm very impressed. That would seem to make the Fast 8 a bargain at the current price.

Incidentally, this is a convenient substitute for a test CD for automated frequency sweeps, if you can hook up your computer to your stereo system:
http://onlinetonegenerator.com/frequency-sweep-generator.html

and this lets you sweep manually, at your speed:
https://www.szynalski.com/tone-generator/

Thanks for the tip,  my machine is connected to my DAC so I'll download and try those programs.

Its been a while since I've had my Oris setup so I'm going from memory, but they sound very similar for a lot less.

You can see pics  of my speakers and more about the my impressions of the Fast 8's here:

https://www.audiocircle.com/index.php?topic=166326.20

Mike