3 years later USB is still a can of worms. I would suggest you look into AES67 protocol. You have the skills to make something good from the ground up.
(I'm slowly reading all thread)
I too prefer high (4k-5k) crossover points, when not using widebands (with tweeter helpers very much higher). Not sure if it's related to phase or other characters of the drivers merging, related to coherent reproduction of the vocal range.
My current speakers have a 4k XO point and they seem coherent.
A perfect 360° shift is very unlikely to happen in reality when crossing mid and tweeter, so I believe people hear the effects of the classic 2k cross.
Thanks Tom! Just finished the amp this weekend. Bought the boards many months ago, only recently realizing the lme49710 stocks were dwindling fast. Glad I completed now. I'm absolutely lovin' it.
Currently have a makeshift volume control connected it, while I'm waiting for some pcbs to come in for single ended preamp that will go through your THAT driver.
Very nice!
I changed my case plans from a custom case to a Modushop 3U dissipante: I got it the other day, and a plain steel sheet for a mounting plate (I don't like the pre-drilled grid) so the build should pick up pace now. I was going to use the 2U but I'm using 2 single-secondary 21V 100VA transformers rather than a single dual-secondary, and the extra U gives me room to comfortably stack them one above the other. My (revised!) layout is similar, with both Modulus-86 boards on the same heatsink, but my chassis will also include a relay attenuator and a remote control receiver board to control volume and power. Photos soon, hopefully!
Bill, you already have asked this question in a separate thread. My recommendations on that thread stand. Kemet has purchased NEC Tokin; I expect the so-called Kemet relays are really NEC Tokin. Kemet started life as a capacitor (largely tantalum and ceramic) company and in recent years has gone on an acquisition binge much as Vishay did.
Hi Brian,
Yeah, I was asking about phono level there (and have a nice bag of reed relays for that now). I hadn't specifically asked about line level on that thread as wasn't sure of requirements. Still not but getting closer. As Tom uses relays in some products and has better measuring gear than most of us thought would check. If I can stop the mission creep should get away with around 40 relays in it.
Yeah, I was asking about phono level there (and have a nice bag of reed relays for that now). I hadn't specifically asked about line level on that thread as wasn't sure of requirements. Still not but getting closer. As Tom uses relays in some products and has better measuring gear than most of us thought would check. If I can stop the mission creep should get away with around 40 relays in it.
I've used a bunch of Takamisawa (made by Fujitsu) RY-12W-K high sensitive miniature signal relays: they use gold overlay silver-palladium contacts and sound fine to me (though I don't have access to the kind of measurement kit that Tom has). If you need it, they offer a make-before-break version (RY-D type), and the range includes relays that operate at various coil voltages.
The RY-12W-K appear to be very similar to the Panasonic TXS that I recommended in my posts on the other thread.
Bill, for small-signal audio (line-level signals and smaller), you want to pay attention to the "Minimum switching load" (or "Min. switching capacity") spec. Both the Takamisawa and Panasonic TX-S indicate 10uA/10mV. If you don't see a similar rating on the relay then it's not the best choice for signal switching. You'll also see that relays with this type of rating usually have some combination of Ag, Au and Pd for the contacts as well as a max current rating almost always <= 1A. (note that the datasheet almost always has a footnote that essentially says "YMMV" with small-signal switching)
That said, reed relays are not usually spec'ed the same way. They tend to have static (DC) and dynamic (AC) contact resistance ratings.
It's instructive to look at what various audio manufacturers use for signal switching in their equipment. I often browse the '6 Moons' reviews as they do a great job of giving you photos of the guts of products and you can usually read make/model info off the components. Not all high-end manufacturers make what I consider good choices in relays. Benchmark Media just announced their HPA-4 headphone amp with relay-based stepped attenuators -- I'm anxious to see what they use under the hood.
Bill, for small-signal audio (line-level signals and smaller), you want to pay attention to the "Minimum switching load" (or "Min. switching capacity") spec. Both the Takamisawa and Panasonic TX-S indicate 10uA/10mV. If you don't see a similar rating on the relay then it's not the best choice for signal switching. You'll also see that relays with this type of rating usually have some combination of Ag, Au and Pd for the contacts as well as a max current rating almost always <= 1A. (note that the datasheet almost always has a footnote that essentially says "YMMV" with small-signal switching)
That said, reed relays are not usually spec'ed the same way. They tend to have static (DC) and dynamic (AC) contact resistance ratings.
It's instructive to look at what various audio manufacturers use for signal switching in their equipment. I often browse the '6 Moons' reviews as they do a great job of giving you photos of the guts of products and you can usually read make/model info off the components. Not all high-end manufacturers make what I consider good choices in relays. Benchmark Media just announced their HPA-4 headphone amp with relay-based stepped attenuators -- I'm anxious to see what they use under the hood.
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Yep. Not specified = don't use.
As opposed to the power relays, which skip the gold on the contact surfaces. I suspect the gold would go *POOF* on the first contact mating at any significant current anyway and you'd be left with dirty switch contacts.
There are other considerations to keep in mind with relays (or any switching really). Ideally you'd want the switching to happen without any audible pops or clicks (aside from the relay itself). You'll also want to consider the 'offness' (i.e. off attenuation). Depending on what you're trying to switch, that could mean that you use a DPDT relay to switch to a middle point, which is then grounded when that input is not in use. Self (2014) has a whole chapter on that, that I highly recommend reading if you're doing any line level switching.
Self, D. (2014). Small Signal Audio Design (2nd ed.). Waltham, MA: Focal Press.
Finally a use for Six Loons...
Nice with a compete to the Neurochrome HP-1.
The THX AAA technology is cool. They use all sorts of feed forward and other tricks. Tom