Author Topic: Trairos  (Read 27247 times)

Offline richidoo

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Re: Trairos
« Reply #30 on: June 13, 2015, 09:13:45 PM »
Cool, glad to know you guys are watching. I'll post more often. When/if I have a g2g you are welcome to drop over Don.

The Jantzen Red cap is pretty detailed, without being overly so. I find it very musical, complements the warmth and detail of my Satori tweeters. I don't feel the need for more resolution at all.  A bypass cap would need to be pretty darn resolving to notice a difference, imo. But I'm sure it's possible, maybe with teflon?

A bypass cap does add 90degrees of phase shift to the mix, which is supposed to be harmless, if not inaudible, but it's there so I beleive it's audible, so I prefer to use just one cap that is good enough top to bottom. ymmv.

What bypass did you have in mind Jim?

Offline jimbones

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Re: Trairos
« Reply #31 on: June 14, 2015, 09:39:33 AM »
hmm, now you have me thinking better to leave well enough alone. jupiter? I don't see how it would add phase shift since you are bypassing a cap that is already in the circuit and just changing the value.
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Offline richidoo

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Re: Trairos
« Reply #32 on: June 14, 2015, 06:35:28 PM »
I've heard Jupiters are nice. I think Mike said something like "out of this world..."    :D   You're probably right about the phase.

Offline richidoo

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Re: Trairos
« Reply #33 on: July 19, 2015, 10:36:00 AM »
I reduced the 2way Kairos' passive crossover's baffle step correction to 3dB. Mids move forward in the mix which I like, but there is less bass extension. I think 4dB of BSC might be about right for a stand alone sealed Kairos in a small room with bass reinforcing boundaries.

But since this is supposed to be a 3way, the slightly thin bass will be supplemented with a separate bass driver so it's OK. I made this BSC change to try to reduce the chestiness sound, but it persists, though lessened. The overall sound of the speaker is better so it's a net positive for me. I am tweaking the tweeter resistor now, with interesting results.

I bought some Mills wirewound 5R resistors for the tweeter but it was too hot. I tried 10W 6.2R metal oxide, a little too soft, and it lost a lot of life. Interesting. So I compared a xicon 5W 5R MOX with the Mills 12W 5R wirewound, OMG what a huge difference. Same resistance value, but a gigantic difference in SQ. The wire resistor is much more alive and detailed. Not surprising since with wirewound the signal goes through copper/nichrome wire, while with MOX the signal goes through  a film of metal oxide (rust) painted on a ceramic insulator. So I ordered some Mills 5.6R resistors, I'm hoping that's just right, reducing the treble energy, but not killing off the life and detail.

An interesting question is whether a more detailed sounding wirewound resistor needs to be a lower value than duller sounding MOX resistor in order to "musically" balance the treble to the mids?

I put on "Blue Trane" this morning, and to tame Lee Morgan's bright snappy trumpet I resorted to the 6.2ohm MOX. The life is much less, but the brash is under control. I might end up going up to the 6.2R Mills. What's another $10 of shipping for 1/2 oz merchandise? Sonicraft is the only seller I could find with a large selection of Mills in stock.

So I'm working on the Trairos bass cabinets again because with the Kairos' baffle step correction (bass boost) reduced I am lacking midbass fullness and low bass. So the bass drivers need to come back into the system instead of running Kairos 2way alone as I have been to avoid the chestiness of the bass boxes. So I must now find a way to reduce the chestiness. I have tried absolutely everything over the last year, but  there is only one thing left to do... Port it.

I chose these bass drivers, Eton 11-581, because of how great they sounded in previous ported commercial speakers I owned. No hint of chestiness at all, crystal clear from 30Hz up to 1200Hz in that speaker.

One way to determine whether a driver should be ported or sealed is by looking at the "EBP" spec, Equivalent Bandwidth Product.

From Eminence website:
"EBP

This measurement is calculated from driver specs by dividing Fs by Qes. The EBP figure is used in many enclosure design formulas to determine if a speaker is more suitable for a closed or vented design. An EBP close to 100 usually indicates a speaker that is best suited for a vented enclosure. On the contrary, an EBP closer to 50 usually indicates a speaker best suited for a closed box design. This is merely a starting point. Many well-designed systems have violated this rule of thumb! Qts should also be considered."

Both the bass driver's and mid driver's EBPs (and their low Qts') suggest ported boxes, even though they can technically still be used in sealed box. Since I know the Etons sound clean in ported box, I will try porting them first to confirm my suspicion. If it clears up the chesties then I will port the Satori also.

The idea is that the reflex port will damp the movement of the cone and reduce cone excursion at lower freqs, which reduces distortion. Hopefully it will be the KIND of distortion I want to reduce. There really aren't any other options, I've tried everything else. If this doesn't work then it's back to commercial speakers... haha

I am a little intimidated about doing more ported boxes after my utter fail with the Econowave speakers. There I used box sim software and used the "optimum" calculation, which made the bass too low and too punchy, like a disco. After a dozen failed attempts to make that box sound good I have the fear that designing a reflex box is a dark art that must be difficult. In that case I was using compromise drivers in way too large a box because the sim said so. I didn't yet understand how a port really works and how to tune it which I think I understand better now. In the case of these Eton and Satori, there are published hifi oriented reflex box designs that should sound good, rather than relying on the sim software's best guess which uses the old reflex port equations. The equations describe how to make the reflex port as efficient as possible and play as low as possible, nothing to do with SQ or musicality. So I'll try the suggested audiophile ported box designs for these drivers and see how they sound. Any port design needs to be tuned a little anyway, which I will attempt to with more understanding this time. The things that can be tuned are the box volume and the port length. The driver specs remain constant as does the port diameter.

If this works I will be happy and relieved. This chestiness problem has been a major sore for a long time and is prompting me to move the stereo to a different room, build different speakers, all kinds of compromises that I can sweep away if it can be fixed. I think these drivers are among the worlds best. Hopefully I am right and they are just lacking optimal acoustic loading.

That's it for now.
Rich
« Last Edit: July 19, 2015, 02:37:47 PM by richidoo »

Offline richidoo

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Re: Trairos
« Reply #34 on: August 02, 2015, 05:55:39 PM »
I ported the bass bins today. It was hard to cut that first hole in the pretty box. It is tuned low to 20Hz right now, with -9dB at 20Hz, which is supposed to net flat response in room. It sounds nice and not too punchy, but it can punch if needed. I think I will want it a little dryer, so I will try shortening the port down to as low as 16", which I think is 25Hz?  I also want to try reducing the box volume from 3 cu ft down to 2 cu ft.

Playing sine waves at about 10W from 20-29hz shook the whole house, rattling everything in the room.  8)

I'm also working on an analog active crossover to avoid the cost in money and time needed to develop a passive speaker level crossover between mid and bass. Low pass low frequency filters for speaker level require a very large inductor, expensive and too big for air core. I am very happy with the passive crossover between mid and tweets, so I would keep that. Using a line level crossover between the mid and bass would use cheaper parts, easier to design, and better performance by eliminating the big coil.

There are three options: passive RC (resistors and caps) line level crossover (PLLXO,) Passive LC (coils and caps) line level XO (like Marchand XM46,) or active Sallen Key filter LR2 XO. I'll probably tinker with them all eventually, but for the G2G I need to pull it together quickly, so I'm thinking of trying the Marchand balanced XM46 as ~250Hz 12dB hipass for the mains, then use an active 250Hz -12dB sallen key filter to the bass drivers. If I do both crossovers with active, then I can make a baffle step correction, but the mains passive already has 3dB BSC, so the active BSC is probably not necessary. I'd like to keep opamps out of the signal path for the mains, but they are harmless enough in the bass.

The other option is to make a full 3 way active crossover with 6 amps and all active 12dB crossovers. Eventually I'll do that since I have all the amps already, but not sure I can get that going and fine tuned before g2g.  Maybe?

Edit: The current bass alignment needs all 85 liters to make the 24" port work, so the port hangs out of the box, since the port itself takes away from the box volume. But if I end up with shorter port with higher tuning, especially with a smaller box, then I can fit it all or mostly into the box so it will look better.
« Last Edit: August 02, 2015, 06:00:21 PM by richidoo »