Thoughts on Z19 XO

[Coelacanth]

My plans to build Altec 19 inspired speakers are now under way, with the 811b horn I ordered in transit. I have been in touch with Bill @GPA and am working through shipping options to get the drivers to New Zealand. I have also decided upon a plan for the cabinetry - more on that later.

Decision on which XO to use is now the only hurdle. GPA make their replacement XO, which is one option, but the Zilch version would likely cost me less, and I am happy to do the work myself. I do not plan on bi-amping however, wheich I understand is one of the key benefits of the Zilch design. I hear mixed reviews re sound quality.

Just looking for some opinions before I commit.

Thanks

[westend9]

It's been a while since I looked at Zilch's Z-19 but I remember other Altec users building and enjoying the network. You could probably build a hybrid Z-19 and construct it to easily punch in your own values of components. I use active crossovers so am partial to those.

What do you have in mind for the enclosures? Are you building the stock Model 19 construction? There are a few other box designs out there so if you have particular needs with your listening space, there are options. FWIW, I have big MLTL cabs, designed by GM and I wouldn't go back to the stock cabs.

Hope you can take some time to post your DIY efforts on the Forum so others can benefit (like me, lol).

[Coelacanth]

It's been a while since I looked at Zilch's Z-19 but I remember other Altec users building and enjoying the network. You could probably build a hybrid Z-19 and construct it to easily punch in your own values of components. I use active crossovers so am partial to those.

What do you have in mind for the enclosures? Are you building the stock Model 19 construction? There are a few other box designs out there so if you have particular needs with your listening space, there are options. FWIW, I have big MLTL cabs, designed by GM and I wouldn't go back to the stock cabs.

Hope you can take some time to post your DIY efforts on the Forum so others can benefit (like me, lol).

I am open to cabinet designs. If your MLTL's sound better than stock, Id like to see the plans...

[westend9]

Give me a few minutes to find the build threads, my bookmarks are all messed up. In the meantime, you can follow this link to information about the Z-19: ALtec Model 19-XO upgrade discussion - Page 5

Build thread of my enclosures:GM's MLTL with 416-8B

[Coelacanth]

Thanks Westend... love to hear more about how they sound...

[westend9]

What GM surmised by using an MLTL design and what is readily audible is that the "West Coast bump" of the original stock Model 19 cabinet disappears. This bump in the frequency response is at about 100-150hz. The TL action of the cabinet also affords the 416 woofer to reach down to it's Fs of below 30 hz. The removal of the bump and the TL afford a very easy roll off to the very lowest tones. The best way I could characterize it is that the bass is effortless. I didn't notice it right away since my ears were trained to hear that concussive slam at 100 hz but the bigger cabinet plays much lower. I'm not an organ music guy, preferring easy jazz and a mix of rock and blues so most of what the Altec woofer does well for that is all present and has an accurate presentation of those lower frequencies.

Since I'm using an active crossover with a 24db filter and pulling the 811/802g in at around 1000-1100 hz, it is letting the woofer and the horn operate in their best ranges, IMO. I also use a Heil AMT1 super tweeter om the very top crossed in at 9 Khz to add some sparkle on the top and trick the ear to a more spatial presentation because of the Heil's dipole effect. It is tricky to dial that in with a third amp and it can be overdone. The Heil AMT is very efficient and doesn't need a lot of watts to get the dipole thing evident. I know some guys that use the same and block off the back of the Heil. I find it to be a neat trick so let it happen as built.

[Coelacanth]

Thanks for your contribution here Westend. It has got me to thinking... what am I really trying to achieve here? I have come up with some answers to my own questions....

Firstly, I am not a person who has any great understanding of electronics or sound design, which is why I have headed towards well-trodden paths in choosing to recreate the Altec 19s. I am open to deviation from this path, but only if such deviation brings measured improvement - and I don't have equipment for measuring, so I will again be relying on others.

I guess I could just clone the 19's and be done, but if the tweaks are easy enough, it seems silly to ignore them.

I have come to realise that a big part of the what attracted me to the 19s is the look. I love how they look. It would be amazing if I could recreate the overall look of the 19, whilst incorporating improvements. I wonder if there is an MLTL design that could be worked into more cubic than rectangular form? Pushing the altec cabinets backwards instead of up?

I have wood working skills on my side. I recently built a kitchen out of plywood, using layups of ply to create the impression of large monolithic ply slabs. I wonder if the same technique could be used effectively with speaker cabinets? I could run down 50mm strips of 18mm MDF, then glue and screw them into a layered cabinet shape... labour intensive, but the outcome would be seriously solid.

I have approached GM via PM to see if he can contribute here to this. Thanks to everyone who has already.

[Alien_Shore]

As many have found here, especially concerning the M14 and M19 is that the engineering that went into those designs is pretty hard to beat, even with 40 years of advancement in technology. That said, if I was to work on a custom design that is similar to the M19, I'd first start with good measurement of my drivers on hand and let the actual numbers do the talking. Today's enclosure and network simulators make this pretty simple, even for the novice. With that info, you can effectively design an optimal system for your equipment.

I realize that you do not have the required equipment, but as I found out a few years ago, it's pretty cheap and easy to get what you need for a really good measurement setup.

[Coelacanth]

That is some good advice. Thanks Mike.

Regarding your comments about the research that went into these designs, I am sure you are right. As a former owner of Klipschorns, I have a huge respect for the giants upon whose shoulders our modern designers stand.

Incidentally, I had a friend who invested many thousands in Avante Guarde Duo Omegas at the same time I had my old Klipsch's. Now I am certain those speakers, driven by his classy amplification offered more of this, that and the other over the old Khorns, but I was through listening after 15 minutes. Those old monsters sure knew how to play music, by comparison. I suspect the 19's will be the same.

[GM]

I didn?t follow any of Zilch?s contributions, only learning about them right before he quit posting/died, so didn?t get a chance to do any audio ?bench racing? with him, though quickly browsing through Westend?s links, Zilch outlined the caveats to using his XO, so at minimum, the cab?s baffle width, woofer/horn c-t-c spacing, offset must be close to the M19?s.

Others who have compared XOs will have to give their subjective opinions/thoughts to hopefully give you enough info to make at least a semi-informed choice. For sure, I recommend making them adjustable and ideally use PIO caps.

WRT construction, sure, you can make your own ?plywood? panels, just skip the MDF, but why bother when [11] lam BB, apple or marine grade with some bracing is all you need. If [13] lam is used, you can often skip the bracing except for the one that mass loads [couples] the driver to cab.

Any [ML]TL can be folded and often are for ?compact?, ?sub? duty alignments, ditto the M19, though the vent[s] must either be on the rear sides, rear or bottom. It will obviously alter the internal construction a bit with the horn/spacer section sealed off, making the cab even deeper. This reduces the bass ?cab? to ~6.3 ft^3 minus the woofer and any bracing, so if we double the depth it should wind up around 12 ft^3 net and really deep. Factor in that they perform best overall toe?d in and the ?look? you want will be spoiled if not sitting in the ?sweet spot?.

GM

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Incidentally, I had a friend who invested many thousands in Avante Guarde Duo Omegas .........., but I was through listening after 15 minutes.

You lasted longer than me...........

GM