Bolton fullrange drivers

[sachu888]

I think they are Bolton.I talked to an ex Cosmic employee today. He told me Cosmic used Bolton drivers.

Regards
Sachin

 

[shafic]

I think they are Bolton.I talked to an ex Cosmic employee today. He told me Cosmic used Bolton drivers.

Regards
Sachin

Bolton used to re badge corals, I have heard.

regds,
shafic

 

[sann]

San

I hope that is not exterior grade mdf

They seem stronger but are not great for cabinet builds and don't take kindly to screws as well

It is water proof and very heavy. Will need to check the grade.

 

[jls001]

It is water proof and very heavy. Will need to check the grade.

Green and pinkish coloured MDFs are usually outdoor grade. I don't know for sure if they're called HDF but they're costlier and denser than the regular MDF which are usually pale brown in colour.

 

[sachu888]

Bolton used to re badge corals, I have heard.

regds,
shafic

I called up that Cosmic employee, after our telephonic conversation. He has confirmed that they are Bolton, made in India(Delhi)

Regards
Sachin

 

[shafic]

I called up that Cosmic employee, after our telephonic conversion. He has confirmed that they are Bolton, made in India(Delhi)

Regards
Sachin

I called up that Cosmic employee,

Great work sachin!!:clapping: I thing he is from Mumbai,right?:

 

[sachu888]

Great work sachin!!:clapping: I thing he is from Navi Mumbai,right?

Nothing great in it. He is from Gujarat. Few FMs also know him.

Regards
Sachin

 

[magma]

Green and pinkish coloured MDFs are usually outdoor grade. I don't know for sure if they're called HDF but they're costlier and denser than the regular MDF which are usually pale brown in colour.

actaully they can come in any color
depends on the company making them

cement is added to the MDF
that makes it exteriror grade and more resistant to water

 

[sann]

Back view of the driver I have.

 

[keith_correa]

cement is added to the MDF
that makes it exteriror grade and more resistant to water

I don't know about the cement - maybe some manufacturers use it but it's not true for all exterior grade MDF. At least the ones that I'm aware of use different types of resin for different grades of MDF.

 

[musiklava79]

Hi sann. Really curious to know what kind of build you're doing.

Care to share some details with us please?

 

[sarith]

Back view of the driver I have.

Most of the Bolton I have are from their Delhi factory which are good but Bolton Faridabad are little better imo. I got 2 pair of midrange woofers, a pair of 80watt cone tweeters and a 50watt 12" woofer (nos) all of which are old and sounds nice.

 

[sann]

Hi sann. Really curious to know what kind of build you're doing.

Care to share some details with us please?

I am attempting Tapered Quarter Wave Tube (TQWT) design, which I have read is a little forgiving design and I can compare different FR drivers in it.

 

[Danieljohn]

@ Danial john,

Sir, I have a pair of Cosmic 2 way speakers. These speakers are producing nice sound according to my ears. With my Marantz 1060 they are singing. I suspect the mid-range driver is CORAL. Can you identify these, pls?

Here is the link. They are looking like same. May be they are CORAL 8' II.

Coral Speakers

regds,
shafic

Shafic open & see it for yourself so you still remember the Link which my brother Robin gave huh.

 

[sarith]

https://plus.google.com/u/0/photos/111085105549379722032/albums/6103435119098906561

 

[sann]

Today's progress.

 

[shafic]

Nice going Santosh!!:clapping:

 

[t.antony]

I recently acquired Bolton 20BF22, 8" fullrange drivers.
There is no specification available on the web. Does anybody know / has measured their TS parameters? Also please suggest a cabinet design for them. Will TWQT be a good idea?

Here are the TS params. These are the measured parameters of the two drivers that I have.

Drivers with high Q as these are more suitable for Open Baffle.

Bob Brines recommends a Q value between 3 to 5 for TQWT. Quarter_Wave_Resonators. I am curious to know how this driver performs in a TQWT. Will you be able to share frequency response plots of your speaker?

Bolton 20BF22 8ohms 40W Fullrange
Thiele-Small parameters:

Fs = 58.93 Hz
Re = 7.70 ohms[dc]
Le = 352.98 uH
L2 = 469.44 uH
R2 = 3.77 ohms
Qt = 1.35
Qes = 1.68
Qms = 6.81
Mms = 13.70 grams
Rms = 0.745250 kg/s
Cms = 0.000532 m/N
Vas = 30.23 liters
Sd= 201.06 cm^2
Bl = 4.817540 Tm
ETA = 0.35 %
Lp(2.83V/1m) = 87.75 dB


Bolton 20BF22 8ohms 40W Fullrange
Thiele-Small parameters:

Fs = 57.68 Hz
Re = 7.70 ohms[dc]
Le = 426.33 uH
L2 = 463.29 uH
R2 = 1.63 ohms
Qt = 1.49
Qes = 1.76
Qms = 9.67
Mms = 16.50 grams
Rms = 0.618569 kg/s
Cms = 0.000461 m/N
Vas = 26.20 liters
Sd= 201.06 cm^2
Bl = 5.118018 Tm
ETA = 0.27 %
Lp(2.83V/1m) = 86.66 dB

 

[sann]

I am curious to know how this driver performs in a TQWT. Will you be able to share frequency response plots

Thanks a lot for the data. I will definitely try to measure the response. I just played one speaker today, without damping the cabinet and only one out of three deflectors in place, the initial impressions are very encouraging. I will also try two comparatively lower qts drivers I have Philips (1.26) and WB Betsy (.78)

 

[nraghunadh]

Today's progress.

Nice and quick build Santosh......:clapping::clapping::clapping:

Cheers.
Raghu