Hello everyone, I was watching Erins Audio Corner a few days ago with Dr Geddes as a guest and he briefly mentioned group delay and used BMR drivers as an example, then said no more on the subject. I became very interested in the tectonic 2” BMR after reading Erins shining review. It seems like the ideal driver for my tastes as I can’t really hear sparkle (I’m 41 as of today) and the frequency and polar response are stand up, which is much more important to me.
But, I worry now about group delay distortion smearing in the time realm. I imagine that the sections resonating semi independently might take enough time in relation to the higher frequency cycles to matter where we’re very sensitive. Would anyone care to share their understanding of this?
Some might be tempted to point out that if I have to ask then I obviously don’t notice it even if it exists and it doesn’t matter then. The thing is years ago I didn’t know about the stereo illusion but now I do, and it matters. There was a time when I didn’t know that my car door speakers were beaming and there was a major problem in the upper midrange response at the listening position, and that most certainly mattered. I wonder if the tradeoff for the wide dispersion is group delay as Mother Nature gives with one hand while taking with the other. Is this concern valid?
I very recently began designing and assembling a small stereo system from the basic components. Kabd amplifier boards, open frame power supply, raw drivers, ect. I chose a two way system with the BMR 2” not because I couldn’t implement a decent three way, but because I felt I didn’t have to with the BMR. If there’s a real problem with the BMR’s I’ll be looking at the RS100 or RS75 and one of the reference tweeters. There’s a chance I’d go for one of the other Dayton 28mm tweeters because of availability. I have some beliefs regarding crossover points that might be too careful but this can wait to be discussed under after the group delay thing has been sorted.
My bookshelves currently have the Tectonic 2”, Anarchy 704, and RSS210 passive radiator on ~60w and 15w respectively. I’m really happy with the result but I want to make sure I’m not missing something that once I perceive it it’ll bug me ferociously. Btw is Erin @bikinpunk here? He’s Erinh on diyma where I’ve basically learned everything I know.
But, I worry now about group delay distortion smearing in the time realm. I imagine that the sections resonating semi independently might take enough time in relation to the higher frequency cycles to matter where we’re very sensitive. Would anyone care to share their understanding of this?
Some might be tempted to point out that if I have to ask then I obviously don’t notice it even if it exists and it doesn’t matter then. The thing is years ago I didn’t know about the stereo illusion but now I do, and it matters. There was a time when I didn’t know that my car door speakers were beaming and there was a major problem in the upper midrange response at the listening position, and that most certainly mattered. I wonder if the tradeoff for the wide dispersion is group delay as Mother Nature gives with one hand while taking with the other. Is this concern valid?
I very recently began designing and assembling a small stereo system from the basic components. Kabd amplifier boards, open frame power supply, raw drivers, ect. I chose a two way system with the BMR 2” not because I couldn’t implement a decent three way, but because I felt I didn’t have to with the BMR. If there’s a real problem with the BMR’s I’ll be looking at the RS100 or RS75 and one of the reference tweeters. There’s a chance I’d go for one of the other Dayton 28mm tweeters because of availability. I have some beliefs regarding crossover points that might be too careful but this can wait to be discussed under after the group delay thing has been sorted.
My bookshelves currently have the Tectonic 2”, Anarchy 704, and RSS210 passive radiator on ~60w and 15w respectively. I’m really happy with the result but I want to make sure I’m not missing something that once I perceive it it’ll bug me ferociously. Btw is Erin @bikinpunk here? He’s Erinh on diyma where I’ve basically learned everything I know.
These are different things. Group delay relates to a response measurement. Dispersion is shown through several response measurements, where each could show different group delay.
Could you link the video so we can see what part you're currently focussed on...
BTW yes, Erin is here.
BTW yes, Erin is here.
At around 24 minutes Geddes is talking about minimum phase and group delay. Right at the 25 minute mark he specifically mentions BMR radiators as having audible issues. The entire video is great but this is what prompted the post.
What I hear him saying is that it is high. What you want to know is how audible this is. Dr Geddes also mentions that the information detail is limited.
Here, you will see some information on the audibility of group delay. There may be other sites with similar information if you prefer it in a different format. - https://ieeexplore.ieee.org/document/9450008
This assumes you can get data on the drivers.
Here, you will see some information on the audibility of group delay. There may be other sites with similar information if you prefer it in a different format. - https://ieeexplore.ieee.org/document/9450008
This assumes you can get data on the drivers.
Thanks allen. What I was looking for was general knowledge of this being a downfall of BMR’s. I’m not looking to put these under the microscope so to speak, I just wanted to make sure there’s nothing overtly wrong. I enjoy the speakers and I’m glad I won’t be ordering more parts and cutting more holes in an attempt to correct my possible concerns. Thanks for your input 🍻
There is a thread here - https://www.diyaudio.com/community/...-high-spl-low-distortion-with-a-2-way.334757/
You should be able to contact Dr Geddes there and ask a question, since the topic there wanders a little. I see you used the paging system ( @Lawnboy ) in your first post as a way to get someone's attention.
You should be able to contact Dr Geddes there and ask a question, since the topic there wanders a little. I see you used the paging system ( @Lawnboy ) in your first post as a way to get someone's attention.