Introducing: The Pit Vipers (Ooh Yeah!!!)

[djg]

I built the late Jeff Bagby's Continuum design. Certainly a well known DIY speaker. Included in the kit documentation was an interior picture of the original Bagby built solid maple item. The chosen acoustic treatment was eggcrate mattress topper foam, really stuffed in there. I used the much thinner gray pyramid acoustic foam included in the kit. It's a matter of faith in my mind that the late designer greenlighted this material.

[Serenitynow]

That might just work. Of course, the smell is strong until it dries. But, probably worth a try as I do have alot of insulation left over from the bathroom and basement remodel

[djg]

A man my age loves that smell.

[Serenitynow]

Yeah. I remember my mom used it when I was a kid

[Paul Carmody]

Perhaps I missed it, but what is the actual impedance of the Pit Viper? I've been waiting for a good DIY design like this that I could build and it'd look properly paired with a vintage 70's receiver if executed correctly. However, a lot of us stay away from "modern" speakers (of this design) because we really don't want to push ~3.4ohms with a 40+ year old receiver (looking at you Wharfedale Lintons).


We have those memories of a friend's dad who had a Cerwin-Vega or JBL setup like this that'd slam your chest with bass. We still want that...only with a bit of actual sound-staging and accuracy now.

This is the system impedance of the Pit Vipers. I've written about this before on my site, but to simply boil down a speaker to a single number for its impedance is very misleading, because it varies across the frequency spectrum. I suppose what matters most is the impedance MINIMA (also sometimes the phase angle, but that's a story for another day), which in the case of the Pit Vipers does get down to 4 Ohms at a few places. But in my defense, so do a lot of commercial speakers labeled "8 Ohms nominal."

https://sites.google.com/site/undefinition/diy-speaker-faqs/diy-faqs-driverimpedances

Some sites like Stereophile at least measure the Impedance of their speakers when they do a review of them. And this makes for a good comparison. With that said, I did look up their measurements of the Wharfdale LInton (https://www.stereophile.com/content/...r-measurements), and the Impedance measurement has some similarities to the Pit Vipers. I think theirs might dip a TINY bit lower. But bottom line, a powerful amp with big watts is going to be more fun with these than something with flea wattage. But I did test them with a Lepai 2020, FWIW.

To quote from my page:
It should go without saying, however, that you ought to drive these with an amp with a healthy amount of power, regardless. With 100 Watts, you should be able to get around 108 dB. Technically, the woofer can probably take more; according to the simulations, it should be able to get to 111 dB (@200 Watts) before xmax becomes a problem. You may want to use beefier resistors in the crossover than the standard 10 Watt-rated ones we'd normally use if you plan on driving them this hard for extended periods of time.

[981CS]

Some companies do indeed play fast and loose with nominal impedance figures (like Wharfedale). However, others tend to be a lot more forthcoming (like Elac with the AJ designs) and list impedance as the lowest value.

I think this design could likely be listed as "4 ohm" nominal. I agree that you'll want to bring some quality watts to the table to drive these, probably even at lower volumes so that you don't miss out on the dynamics that they appear to be capable of.

Appreciate the design though as this genre of speaker isn't represented a lot anymore. These still have appeal to a lot of folks.

[Serenitynow]

Got the grill frames made and powder coated today.

[9sheng]

The internal support of the box painted some time ago is always unsatisfactory. Therefore, we have put the internal support in the current situation and revised it in recent days. I upload a picture. I have a question about this. Such a large number of supporting frames will have some impact on the internal volume. Will this have an impact on the overall design? If there is any impact, do you want to increase the depth to make up for the occupation of internal support? You are welcome to make comments and suggestions on this. My idea is that such support will improve the overall strength of the box. I will directly paste the internal support frames with woodworking glue and choose MDF as the box material.

Paul Carmody Carmody hopes to get your opinion, thank you all!





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[9sheng]

More pictures

[Paul Carmody]

I love this! This is the sort of internal bracing I wish I had the patience for (maybe owning a CNC would help).

Anyway, I think some of the career engineers here could probably calculate the exact internal volume taken up by all that bracing. An eyeball estimate from me almost makes it look like you might have the equivalent of like another baffle's worth of wood there. if that's the case, then it'd be a safe estimate to increase the cabinet depth by .75" to 1". Again, these are super-rough eyeball estimates. But that's what I'd do.

[9sheng]

Your vision is very accurate. I calculated that the plane area of the internal support is 240428 square millimeters, which is replaced by the plate size ≈ (width) 358mm * (height) 671mm. This size is smaller than the backplane, because the size of the backplane is 358mm (width) * 828mm (height). So I can increase the depth of the box by 18mm (≈ 0.75 inch).

Thank you. I can customize the boards. I am looking for a nearby CNC to process and then assemble by myself, which will reduce a lot of work.​

[Paul Carmody]

If you do go with this bracing, make sure and take lots of pictures! This is bracing worth showing off!

[9sheng]

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[9sheng]

The materials have been delivered. I use two 18mm overlapping panels and a ring to reinforce the mid-range PVC pipe cap.

[Steve Lee]

9sheng, your skills have improved markedly over the past several years - you are most impressive.
Please keep this up as you are an inspiration, here and the world-over.

[djg]

Nice stuff.

I wonder what happened to Serenity Now, he was very eager to build these.

[Serenitynow]

I'm still here.
I got all the crossover components mounted to their boards.
Then, about 500 other things came up and I haven't had a chance to go any further yet.