T Nuts
Why do you think I keep saying that you should come to Bombay more often? I can take you to Nimakwala in Lohar Chawl and show you T Nuts (and many, many other types of nuts). I've seen 5mm and 6mm T Nuts with him, and it's likely he has other sizes too. East or West, Bombay is the best... et cetera. 😀angshudas said:
Re: T Nuts
I knew Bombay has all sorts of nuts, but I am happy to note that the T types are available too. Tarun, when you visit your Lohar friends next, can you find out whether 3-4mm T nuts are available. 6mm T nuts are available in Bangalore.
tcpip said:
I knew Bombay has all sorts of nuts, but I am happy to note that the T types are available too. Tarun, when you visit your Lohar friends next, can you find out whether 3-4mm T nuts are available. 6mm T nuts are available in Bangalore.
Re: Re: Re: Re: Re: Re: Re: Re: TS parameters for Bolton
actually i did anaysis across the freq band from 100Hz to 5k. above 5k energy was less than 10%. I think it was about 5-8%.
what i remember very clearly was 50% of the energy was below 300Hz and 50% above it. that % oddly stayed the same (with minor vairations) no what what we played. To do this we used a 1/3 octaave spectrum analyser. The spectrum analyser could be A weighted or C weighted. I dont remember all the details (please forgive my senility) but the 50% figure still stays in my head. oddly enuogh for most tower type speaker bafffles (6'-10" wide) 300hz is also a good approximation freq. at which baffle step becomes noticeable. If youhave access to some of the old designs using dual voice coil midbasses u will notice that they rolled of one voice coil at about 300hz and one higher up (at tweeter XO).
Another freq I remember was 1250hz where energy below it was 2/3 and above it was 1/3. 2500Hz was 3/4 : 1/4.
as far as push push is concerned Dave (planet 10) is the cheif propoenent of this. his website will give you more info.
push push solves 2 issues.
1. the phase shift when one roll of the BSC woofer
2. distorsion due to the woofer pushing/pulling against the baffle
the other advantage (cosmetic) is that the front baffle does not look so busy with 3-5 woofers on it.
as far as SPL is concerned you expect to get 100db at what freq. 100Hz or 30Hz. there is a big differene in the ammout of air you'll have to move. you'll have to move about 16 times more air to achieve the same SPL at 30Hz as you would to at 100hz. if you want to be exact you'd have to move 16 times more air to achieve the same SPL at 30Hz as you would at 120Hz (2 octaves above 30Hz). So if 1mm is adequate at 120hz you'll need 16mm at 30Hz (same woofer).
Vd = 4 x 150cm2 x 0.3 cm (lin one way) = 180cm3
using my analogy of 3 8" woofers this was a real world test case
Vd in that application was
Vd = 3 x 220cm2 x 0.5cm = 330cm3.
by gut instinct is that you will achieve 100db at 40Hz not more without introducing serious distortion.
I have no way to calulate this and it is fairly quite impossible to do this in real world conditions (room boundraies, liveliness, etc...) so i rely on my past experiences.
Using 3 x 8" woofer per side I had achieved 110db at 40/45hz (I did not test below that as the low E on the bass guitar 41-42Hz was my test signal) in a fairly live room of 250 sq ft with a 9'6" ceiling.
tcpip said:
actually i did anaysis across the freq band from 100Hz to 5k. above 5k energy was less than 10%. I think it was about 5-8%.
what i remember very clearly was 50% of the energy was below 300Hz and 50% above it. that % oddly stayed the same (with minor vairations) no what what we played. To do this we used a 1/3 octaave spectrum analyser. The spectrum analyser could be A weighted or C weighted. I dont remember all the details (please forgive my senility) but the 50% figure still stays in my head. oddly enuogh for most tower type speaker bafffles (6'-10" wide) 300hz is also a good approximation freq. at which baffle step becomes noticeable. If youhave access to some of the old designs using dual voice coil midbasses u will notice that they rolled of one voice coil at about 300hz and one higher up (at tweeter XO).
Another freq I remember was 1250hz where energy below it was 2/3 and above it was 1/3. 2500Hz was 3/4 : 1/4.
as far as push push is concerned Dave (planet 10) is the cheif propoenent of this. his website will give you more info.
push push solves 2 issues.
1. the phase shift when one roll of the BSC woofer
2. distorsion due to the woofer pushing/pulling against the baffle
the other advantage (cosmetic) is that the front baffle does not look so busy with 3-5 woofers on it.
as far as SPL is concerned you expect to get 100db at what freq. 100Hz or 30Hz. there is a big differene in the ammout of air you'll have to move. you'll have to move about 16 times more air to achieve the same SPL at 30Hz as you would to at 100hz. if you want to be exact you'd have to move 16 times more air to achieve the same SPL at 30Hz as you would at 120Hz (2 octaves above 30Hz). So if 1mm is adequate at 120hz you'll need 16mm at 30Hz (same woofer).
Vd = 4 x 150cm2 x 0.3 cm (lin one way) = 180cm3
using my analogy of 3 8" woofers this was a real world test case
Vd in that application was
Vd = 3 x 220cm2 x 0.5cm = 330cm3.
by gut instinct is that you will achieve 100db at 40Hz not more without introducing serious distortion.
I have no way to calulate this and it is fairly quite impossible to do this in real world conditions (room boundraies, liveliness, etc...) so i rely on my past experiences.
Using 3 x 8" woofer per side I had achieved 110db at 40/45hz (I did not test below that as the low E on the bass guitar 41-42Hz was my test signal) in a fairly live room of 250 sq ft with a 9'6" ceiling.
Angshu, this is news to me. I searched almost the whole of SP Road (equivalent to L Road) here but could not find the T nuts. Can you tell me the shop name or address?
Vivek
Vivek
Boltons have arrived
Just wanted to tell all you guys that the Boltons I've ordered from Bolton have arrived. I've actually unpacked and caressed one or two of the drivers. This means that the process I'd followed actually worked... thanks largely to Gooroo Angshoo's help. Needless to say, the price Bolton quotes for a direct sale is lower than anything quoted by dealers, and you're also sure of the item being made by Bolton.
Just wanted to tell all you guys that the Boltons I've ordered from Bolton have arrived. I've actually unpacked and caressed one or two of the drivers. This means that the process I'd followed actually worked... thanks largely to Gooroo Angshoo's help. Needless to say, the price Bolton quotes for a direct sale is lower than anything quoted by dealers, and you're also sure of the item being made by Bolton.
Vivek said:
Vivek, my cousin in Bangalore purchased the T nuts from the small hardware stores in SP road. He only got 6mm and not smaller.
They may not know these as T nuts, so you might have to show them a sample or draw a sketch.
Re: Boltons have arrived
If any one wants to purchase Bolton drivers direct from the factory, you can write to Mr. Monga with your order, I can put in a word, and request him for a stricter QC, whatever it is worth.. But be warned, Bolton still relies on pigeon mail, as Tarun has found out the hard way.
tcpip said:
If any one wants to purchase Bolton drivers direct from the factory, you can write to Mr. Monga with your order, I can put in a word, and request him for a stricter QC, whatever it is worth.. But be warned, Bolton still relies on pigeon mail, as Tarun has found out the hard way.
T Nuts
😎 hey guys this T Nuts is driving me Nuts.... somebody please tell me what are these..... i feel very left out not knowing them .
Binil
😎 hey guys this T Nuts is driving me Nuts.... somebody please tell me what are these..... i feel very left out not knowing them .
Binil
Re: T Nuts
From what I understand, you drill a hole in a wood plank to pass a bolt through, and under normal circumstances, you'll use a nut on the reverse side to grip the bolt. But if the "reverse side" happens to be the inside of a hard-to-reach box, then it'll be difficult to hold the nut while tightening the bolt. In those circumstances, you make a slightly larger hole from the inner side, and hammer a T-nut into the wood. The spikes of the T-nut go into the wood, and keep it in place. Then you can put in your bolt and tighten it whenever you want, without having to use a spare hand or gymnastics to hold the nut in place. At least, that's the theory. Wise Ones who have tried using them tell me the practice is different from the theory, because the T-nut rusts (it's hard to find them made in brass or stainless steel), and then the bolt cannot be unscrewed. C'est la vie. 😀
Check this page for an example of the thing. Here's what it looks like:brokenbinil said:
An externally hosted image should be here but it was not working when we last tested it.
From what I understand, you drill a hole in a wood plank to pass a bolt through, and under normal circumstances, you'll use a nut on the reverse side to grip the bolt. But if the "reverse side" happens to be the inside of a hard-to-reach box, then it'll be difficult to hold the nut while tightening the bolt. In those circumstances, you make a slightly larger hole from the inner side, and hammer a T-nut into the wood. The spikes of the T-nut go into the wood, and keep it in place. Then you can put in your bolt and tighten it whenever you want, without having to use a spare hand or gymnastics to hold the nut in place. At least, that's the theory. Wise Ones who have tried using them tell me the practice is different from the theory, because the T-nut rusts (it's hard to find them made in brass or stainless steel), and then the bolt cannot be unscrewed. C'est la vie. 😀
Angshu is more knowledgeable than me about the Bolton catalog, but I can tell you they do have 10" and 12" drivers. There's one 12-incher with a smallish magnet, rated at 60W, with a paper cone and rubber surround. About Rs.1300. I don't know any T/S parameters for this driver, but it's certainly not the stuff out of which HT subwoofers are made. And there's another higher-power 12-incher, with (IIRC) an accordion-type cloth surround, but it's apparently meant for guitar speakers, not for hi-fi. It costs about Rs.2000. Basically, neither is particularly impressive for good hi-fi woofers, I think. I guess it's not easy to make good large, low-frequency woofer drivers. 🙂roshan101 said:
sub woofers
Thanks tcpip. I know peerless India have good 10", 12" sub drivers, but they dont respond to my emails.
Suranjan, I believe you make such subs. Have you supplied these to anyone in this forum yet? ....just for reference.
Thanks tcpip. I know peerless India have good 10", 12" sub drivers, but they dont respond to my emails.
Suranjan, I believe you make such subs. Have you supplied these to anyone in this forum yet? ....just for reference.
Indian sub woofers
hey guys i was jus going thru Gupta electronics here in jamshedpur .... i was there for picking up some transistors .... he showed me a few sub woofers of one toyotone make .... the quality seemed good .... the sticker on the magnet said 120W he was not able to tell me if tat is the true value or if in rms or pmpo... any way he assuired that i can try it if i want to.... the price lemme come to it .... Rs. 475/- have any of u heard of this brand ... as far as i know these guys used to only make transformers. i'm not sure if i should try them.... well any suggestions.
ashok what about u.
Binil
hey guys i was jus going thru Gupta electronics here in jamshedpur .... i was there for picking up some transistors .... he showed me a few sub woofers of one toyotone make .... the quality seemed good .... the sticker on the magnet said 120W he was not able to tell me if tat is the true value or if in rms or pmpo... any way he assuired that i can try it if i want to.... the price lemme come to it .... Rs. 475/- have any of u heard of this brand ... as far as i know these guys used to only make transformers. i'm not sure if i should try them.... well any suggestions.
ashok what about u.
Binil
hey y not use large pioneer/jvc car subwoofers for ht applications.
These car subwoofers perform quite well when installed in cars. has anybody used any of these speakers viz pioneer/ jvc etc for active subwoofer apploications. I guess they will outperform many local makes of subwoofers including peerless 10" 12" ers. any suggestions
These car subwoofers perform quite well when installed in cars. has anybody used any of these speakers viz pioneer/ jvc etc for active subwoofer apploications. I guess they will outperform many local makes of subwoofers including peerless 10" 12" ers. any suggestions
Re: sub woofers
Since your interest lies in subwoofers, BTW, one gentleman who you can ask, and who both Navin and I feel very comfortable with, is Mahendra Palesha from Pune. He makes subwoofers, and he's been very helpful and forthcoming about offering drivers for similar applications when I'd inquired. Most important, I felt his attitude was the kind I'd like to do business with. 🙂 He has posted on this thread once or twice, I think.
Have you read this post? There I've given some background about what we Indian diyers can do to get Peerless India drivers, and what the caveats are.roshan101 said:
I get the feeling that a lot of Indian diyers have at one time asked this and similar questions. I suspect they'll be watching to see what answer you get. 😀
Since your interest lies in subwoofers, BTW, one gentleman who you can ask, and who both Navin and I feel very comfortable with, is Mahendra Palesha from Pune. He makes subwoofers, and he's been very helpful and forthcoming about offering drivers for similar applications when I'd inquired. Most important, I felt his attitude was the kind I'd like to do business with. 🙂 He has posted on this thread once or twice, I think.
MP can be reached at palesha@vsnl.com i think.
he is a very nice person. i saw his 10" and it looked the part only he did not have T/S specs. Also his drivers are more geared to car audio. the T/S parameters are more suited to small boxes highish F3s etc... at the last show I was NOT impressed with the sound from the room.
I understand that he was demoing his subs but hte subs overpowered everything on the floor. I took refuge in Khushroo's Mangers.
From what I have heard of his woofers they certainly have the displacement capability. I only wish the bass was better defined and more subtle. The woofers might do fine for trance, hindipop and disco though.
he is a very nice person. i saw his 10" and it looked the part only he did not have T/S specs. Also his drivers are more geared to car audio. the T/S parameters are more suited to small boxes highish F3s etc... at the last show I was NOT impressed with the sound from the room.
I understand that he was demoing his subs but hte subs overpowered everything on the floor. I took refuge in Khushroo's Mangers.
From what I have heard of his woofers they certainly have the displacement capability. I only wish the bass was better defined and more subtle. The woofers might do fine for trance, hindipop and disco though.
Re: hey y not use large pioneer/jvc car subwoofers for ht applications.
Have seen Pioneer tube shaped passive subs for car stereo (priced Rs 5000+) - but thats ready made. No fun. But its true they perform quite well.
Hey Binil, Toyotone subs are available here as well rated 180W, 8". Unfortunately thats the max size here. Looking for 10-12" for high SPL and good sound reinforcement. Wonder if thats too much for a 15x20 ft room. Let me know if you happen to test it. ....afterall you've nothing to lose as your dealer is willing to give for trial.brokenbinil said:
akshay said:
Have seen Pioneer tube shaped passive subs for car stereo (priced Rs 5000+) - but thats ready made. No fun. But its true they perform quite well.
Thanks a lot for the info. Will contact the gentleman... after I get some feedback on these Toyotone subs. After my misfortune at bazee, first priority is to get drivers locally . A bit paranoid when it comes to ordering something I've never seen. Handling in courier/lorry/mail is another nightmare.navin said:
He gave me T/S parameters when he wrote to me. I can give you details but it's better you get them from him directly.navin said:
The T/S parameters have a lowish Qts, in the 0.3-0.4 range. They seem more suited for vented applications (which I guess includes 99% of the world's subwoofers). If you do sealed box with them, it's possible that you'll get tight bass, but then you may need to use eq to get the Fc down to the twenties. The free-air resonance is in the thirties, IIRC.
Re: Re: hey y not use large pioneer/jvc car subwoofers for ht applications.
It all depends on who you're dealing with, I guess. I just mentioned a couple of days back about my receiving a batch of drivers from Bolton in Faridabad, absolutely okay.roshan101 said:
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