Trairos

[richidoo]

An Update, for anybody following along...

The electro coupling caps on the sound card's outputs have broken in, so it sounds much better than it did when I first started using it. I've owned this card for 8 years but I'd never used the line out jacks. The protection electros on the tweeters also sound a little smoother. I don't notice the gravel like before.

The cabinets are underdamped due to not enough acoustic damping inside. Voices are better now than they were with passive crossover on the mid box alone, but solo piano (the acid test for clarity) still sounds a bit loose on some notes. I will add pink 2" stuffing glued to all interior surfaces, then add more until the Qtc bottoms out at the designed .5. Active amps can make up for the lost SPL. I stuffed them lightly because I intended to make passive crossovers for them sometime in the future. But now I see the big benefits of active amps so I don't care about passive. Passive can still be done at the cost of a few dB of sensitivity.

I downloaded National Semiconductor's free version of MultiSim Blue and will be using that to create PCBs to build the six I-60 monoblock amps for power. That will be a big project for the winter.

The old XP computer probably needs to go. It drops out too often from background processes, network issues (buffering songs,) etc. I'm deciding whether to go with analog crossovers and use a small linux computer for transport, or build a Win8 i5 PC and store songs locally, run linear phase crossovers and JPlay with plenty of headroom to avoid dropouts. The price difference is about 4 to 1 in favor of the analog/cubox method, but what about value?

I think the Firepod DACs are good enough for high end system when used with active crossovers and amps. Going active adds so much that it more than makes up for any refinement lost in the pro audio DAC. I think I can improve the Firepod by upgrading or removing the output caps. It already uses my fav opamps that I would use in an analog XO.  But greed tells me that it would be nice to have both the active XOs AND an ultra refined DAC like my Buffalo. Decisions...  I'll probably have to try the analog crossover to see which is better. It need Belleson +/-15v regulators and a good volume control to adjust phono level, it's more of a preamp/xo combo so it won't be as cheap as I have been imagining. I need to add it up and see how it compares to building a computer.

This morning I purchased "nMedium Play" JRiver remote control app for my Windows Phone after the trial had expired. It's not bad. I can browse and search the library pretty easily, and use transport/volume controls. That makes up for the lost Sonos remote capability.

Instead of playing music for my morning coffee this morning, JRiver had to do an upgrade on itself. I stepped away for a minute and when I returned the upgrade had failed because I did not give Windows permission to install non-MS approved software. And when I cancelled the failed install it went BSOD. Nice. Haven't seen one of those in decades.

Anyhoo, that's where it is today. Next steps are to get more FG into the boxes to make them sound nice and tight. If that succeeds these will be within the top 5% of speakers I've heard. Then i can start listening for smaller flaws.

I'm enjoying the added dynamics and better detail and control that I hear in loud symphonic passages that previously were more like "wall of sound." Now I can hear more inner detail that is calm and matter of fact rather than a clusterf. Despite the added detail, the music is still easy to get lost in.

[richidoo]

Stuffed the tops and bottoms with polyfill today. I started with 4" thick  bonded logic recycled blue jeans batting in 12x12 squares but it is too dense for stuffing a speaker. It did not effect the impedance measurements as much s polyfill did. Polyfill is less dense and more springy so it can fill the whole innards with variable density.  I have it packed pretty tight now. 2 pounds of fill in a box size of 3 cu. ft. (84 liters,) target Qtc .5.

Filling the whole insides very dense is too much, exactly as I hoped. It does seem to have helped the resonance thing which was the goal. Before stuffing I hummed into the boxes and the resonance in midbass was very strong. Not sure how that happens in the small box but it did so that's probably the issue. After stuffing to the gills resonant sound inside the box was way down.

Listening to the Kairos as overstuffed was interesting. No resonance, but it did dull off some of the speed and some sensitivity, especially low freq. Mids and uppers were not affected much by the acoustic damping. The Kairos designer Jeff Bagby recommends filling the back half of the box with loosely packed polyfill batting. I think that will be proven to be good advice.

In the bass boxes the stuffing has even more effect because all the signal is low freq. I think the resonance is gone, but I didn't have as much time to listen to it as 3 way, mostly as 2way tonight. But the speed and zap of the woofer was swallowed up by the stuffing.

Tomorrow I'll try to find the happy compromise of no resonance with speed and micro details restored. Or tolerable resonance with tolerable loss of speed.

I am wondering how compares the full box of low density polyfill to a denser more absorbent material like 1" cotton batting lining the walls while the middle volume is empty. I saw that they do sell the 1" cotton 12x12 tiles at Homedepot.com

[richidoo]

I pulled out about half of the woofer box stuffing last week. It was not enough. I pulled about all but a pound from each woofer, and highly fluffed what remained. That was the most I could get in there without messing up the natural sound. But the bass is still not well damped enough. One of my cheap amps acted up after I did the final stuffing adjustment, so I couldn't test it until today. Carl advised me to get the amps sorted out before wasting time tuning the box as the amp could be the cause of the wobbly bass sound.

Carl dropped by to pick up his DAC and had a listen. His comments are always very helpful in getting me back on track, set in the right direction, and motivated. Thanks Carl!

The amp trouble of last week, plus the difficulty of designing PCBs for Sols amps has set me off on a couple new amp projects. I am building a pair of each of these:
Modulus-86
Sympatico

They both use variations of TI LM3886 chip amp. I will compare them and buy more of the winner to make 6 channels for these speakers. They are both fully balanced amplifiers which will take advantage of my computer audio interface. Then if the interface is found to be the weakpoint I'll build a new multichannel Buffalo3 DAC. I am in love with the sound of Buffalo DACs with Russ White's Legato discreet output stage and PlacidHD BP power supply. My Presonus Firepod might be good enough with some changes, but if not I know where to go. I may just go there anyway.

The Firepod has electrolytic coupling caps on the output. I think they are there for safety reasons needed in pro-audio situations. If I can eliminate those I think it will make a big difference. Also with the new amps I will be using the whole balanced signal rather than only one half of it as I am doing now. Shorting one half of an opamp sometimes effects the other side.

With Carl's volume adjustments on the amps today the system is sounding really good to me, and I am excited about what's coming up.

[rollo]

    Sounding good there professor. Having another ear in the room helps.
   We should call you Sinatra now. " I did it my way" I can see a NC sleepover Rave. Gentleman start your engines.


charles

[richidoo]

Thanks Charie! That would be VERY fun! I have enough room, bring it! But it might be forever before I finish these buggers. 

I am thinking now that this driver wants to be in vented box. I am not getting the clarity that I wanted. I think my prejudice for large sealed box only works with drivers that are designed for that, with higher Q. I am prejudiced because previous ported DIYs I tried sucked. But I may be forced to try it again with these. I think these boxes should be adaptable to vented.

[richidoo]

Update. I suspected the woofer was not playing clear. I experimented with stuffing, but it didn't help. I asked for help on diyaudio, and a local DIY speaker expert called to talk about speaker boxes, Q, acoustics etc. I met him once before but I'm glad to meet him again now that I am doing speakers more seriously than before.

My measurements indicated that my speakers are fine. The problem is room acoustics blurring the sound. So today I used my new OmniMic to better position the speakers, fine tune the baffle step compensation to match the room gain on each side individually, then applied 4 different paraEQs to each speaker to get flat, and R/L level compensations. The digital adjustments available in JRiver are very useful.

The speakers are a foot closer together now, and a foot closer to me. While the sound is still not perfect, it is much better. The room effect has been reduced enough (in the sweet spot) that I can now hear that the room is the problem. Before the room mud was everywhere so there were no clean references, so I assumed the speakers were the problem.

I have some EQ notches of up to -15dB and some boosts of 8dB. I'll probably reduce the boosts as I can hear them causing wicked blooms at those ringing freqs. Speakers can't be moved to positions that would stop those rings at the listening position.

Resulting FR looks good on paper, Flat 20-10k +/-5dB, rolling another 5dB top oct. It sounds flattish, much clearer overall than before. Imaging is better. The bass clarity is 50% better so far on first non critical listening. But the blooming fatness and room ringing can still be heard now and then. 

Now that levels are equalized I'll try increasing the woofer to mid crossover frequency.  The mids can play very low, but they loose dynamics. The woofers can play clean to >1k so I'm safe up to 500Hz, and I can notch the woofer breakup if I need to. My old Ushers crossed 2nd order at 640Hz, with no notch I liked the midrange of those. I have better midrange driver now, and far better center to center spacing. So there's great potential for more tuning.

The OmniMic has a cool feature called "Bass Delay" which shows the room nodes ringing. Now we can see our enemy. We could always see the enemy in the 4 walls and ceiling, but now we see the dirty deed as it happens.

With the bass improved the midrange blooming and peaking is more noticeable now too. Ahh Waiter!?! More acoustic treatments please!

I have some new tweeter DC protection caps coming, 100uF good sounding electrolytics to get rid of the cheap chinese cap harsh on the tweeters, until my new amps are built then I can dispose of the protection cap. The amp I'm using now has a turn on thump so I need the cap for now. The new tweeter amps have opamp servo to remove DC completely from the output.

All the parts to build the Modulus86s have arrived from Mouser, even a new roll of Cardas solder. The Sympaticos came with all the parts already. I keep saying I will start building them tomorrow, but it didn't happen yet! Wintertime I am 1 lazy MF.

Tomorrow will be a fun day of listening to "that new system sound."

[richidoo]

Well, the above experiment was a bust. I had absolutely no desire to listen to these new tweaks.  After a couple weeks I twisted the whole room 90 degrees, a position that I have used a couple times before, it's always the best setup, but it doesn't accommodate a Christmas tree and I'm not always motivated to twist it back after Christmas. So it already sounds good without even placing the speakers.  I listened for a few hours last night.

I finished building the chip amps called Modulus-86. They sound great. I converted the 2way speakers into passive crossover again, so I can do some amp comparisons with only 2 channels of each amp. When i hear them all I will know what amp to put where in the active crossover scheme. The Modulus is so good, I think I will be using it on tweeters and mid, and maybe also on the bass, unless the very similar Sympatico amplifier sound just as good. It should since it uses similar parts and concept, but not exactly. I still have to make the Sympatico ready to play. But I am much less of a hurry with the Mod86 in the system.

[rollo]

  Maybe a bust but a learning experience for you and a fun read for us. Priceless.

charles

[richidoo]

Update:
System finally starting to sound good now.

I inserted Steve's (stereofool) AR balanced tube preamp into the mix and that brought everything to life, filled out the midrange and mid bass. It also enables listening to my SE sources like radio and phono with the balanced input amplifiers. I retubed it last year but didn't use it because it sounds "too pretty," imo, when playing into SE amps. But with balanced output it is awesome. Thanks Steve!!

The speaker boxes still have audible resonances, even after changing the speaker positions, the room acoustic have no effect on the resonance. So I'll have to try a different bracing scheme. It would be cool to use a vibration sensor to see what's really going on, where and what freq. I will try to modify the existing boxes with BW matrix style internal bracing in lieu of the failed corner bracing scheme I tried. Chopping them open will be challenging. Removing the old corner bracing sticks cleanly is not hard, with a sawzall leaving a thin layer of wood at the joint and a heat gun to melt the glue and scrape off the remainder. I have plenty of volume inside the box to burn with more bracing, since the speakers were designed for Qtc=.5. Since then I've learned that Qtc .57 is potentially even better, since the attack is cleaner at the expense of a little more ringing. So adding 1/2" MDF matrix style bracing will bring the Q up and hopefully silence the box to kingdom come. Does anybody know the spacing of B&W Matric bracing panels? How big are the cells? For my speakers either 4" or 6" would work well.

I'm using a HiFace USB>SPDIF adapter now, which is a big improvement over the Sonos ZP80 digital out and the Presonus Firepod digital out. Carl's identical DAC still sounds better than mine, so either his newer design Legato DAC output stage is better, or the USB>I2S input is better than Hiface/SPDIF, probably both.

I am working on the custom active analog crossovers now. The design is finished, I am ordering parts this week. Two separate 3 way crossovers will go into the 3 way amp boxes near each speaker, fed by a full range balanced signal from preamp. The crossovers will have overall baffle step correction adjustable 0-6dB, and attenuating pots on each output as well as true balanced input and output stages. The filter stages in the middle are single ended. I'm using the THAT Corp. 1200 balanced line receiver, and MC33079 opamps which sound great in unity gain to power the crossover filters and for balanced output.

I'm also still intrigued by using tube amplifiers, so the passive crossovers will follow when I finish the active crossovers. Then I can try Steve's matching AR power amp again too.

Spring has sprung in Carolina, bulbs are up and cherry trees are in full bloom, so I can get out and make sawdust. Gotta pull it all together to have a nice G2G soon.

[richidoo]

I finally figured out the low midrange blooming problem. It took a year but a local friend finally helped me understand what was going on. Too much baffle step correction for my taste.

I replaced some junk chinacaps in my Firepod with some Sol-recommended parts for a huge improvement in SQ. (Shhhh: Nichi KL) As it continues to break in I am amazed electros can sound this good, but that's what he promised. Now I can really hear how bad the old caps were when I play an analog source into the input of the Firepod which still has the old shit caps. The inputs have many more and larger shitcaps, so the inputs still sound terrible. In days past I recorded some pretty nice sounding sessions through those inputs and the Firepod mic preamps got rave reviews (for the money) when it was introduced. Just goes to show audiophile SQ standard is higher than pro.  I will upgrade (or eliminate) the input caps and it might be able to stay in the system afterall.

I'm fine tuning the levels now with much less bass bost overall, then see how it wears over a couple weeks, then maybe a G2G. That is if there's any NCs still here?

Hello?

Hellllloooooooooooooo??

AAAAAAnnnyyyyyybbooooooooodddyyyyyyyyyyyyy ooooooouuuttttt Thhhhhhheeeerrrrrreee?

[pumpkinman]

Do I count Rich 

[hometheaterdoc]

I'm still here

glad you are working it out and have found the issues   can't wait to hear it!!

[richidoo]

Hey Guys! 

You are always the first invite to my G2Gs Bill!

[jimbones]

Following along Rich. Wow you are making quite a bit of changes. Mine have been stable for a wile except now that I have a new preamp I had to add some more attenuation to the midrange. I am using Janzen Superior Z caps (red ones) I am thinking of by passing with a premium cap. Do you think there will be audible difference?

[dflee]

Dis shit's way over my head but I would like to hear those speakers ya got there. (I have been tailing your posts)

Don