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Bolton fullrange drivers

sann

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#1


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?
Regards,
~sann
 
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yogibear

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#5
Yep, if you want to juice them fully, TL is the way to go. As enlightened by Nikhil, am too learning a lot on TLs and its the best way to "Milk the FLs".

Further placing a super tweeter at the top gives you the full sound. Very nice FLs with shiny dust caps. Great find indeed !

Had they been 12", the "Audio Nirvaana" would be in hand.

Even if these have great sensitivity like 100 dB or more, the tube amp will do wonders !
 

Danieljohn

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#6
They are not that Sensitive ! :eek:hyeah:

@ Yogi what are these expresssions "juice them fully Milk the FLs" Man ? :lol:
 
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yogibear

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#7
(To make one laugh). Thats the way I aim for the objective when I use the FLs. No crossovers, just uncoloured music and full optimisation thru TLs. Getting the best out of them !
 

shafic

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#8


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?
Regards,
~sann
Nice find sandeep!!

Are they Alnico ones?. Supposed to be very good FR speakers, Congrats.:clapping:

https://www.youtube.com/watch?v=6j5_cpkpBk4
 

sann

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#9
I Suggest TL's & Could you post rear side pics also.:)
Thanks Danieljohn, I have temporarily put them in Philips HiQ cabinets, which is ~27L bottom ported, and these drivers are showing their potential, however lower mids are sounding muddy and lows are a bit boomy, they are demanding a better place to live and sing.
Will post the back side pic.
Are they Alnico ones?.
Thanks Shafic, no they are ferrite, never knew that bolton also used alnico's
Had they been 12", the "Audio Nirvaana" would be in hand.
Even if these have great sensitivity like 100 dB or more, the tube amp will do wonders !
Thanks yogibear, I have an eye on the bigger Bolton FR's :) as Danieljohn said they are not that sensitive, I feel they are around ~93 db, similar to Philips 8" FR's, I am currently driving them with a 4W SET amp.
 
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sachu888

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#10
Nice find sandeep!!

Are they Alnico ones?. Supposed to be very good FR speakers, Congrats.:clapping:

https://www.youtube.com/watch?v=6j5_cpkpBk4
I don't think Bolton ever made drivers with Alnico magnet.
BTW the video you linked belongs to a member here. He made 60lt sealed enclosure for 10" Bolton drivers.

Regards
Sachin
 
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Danieljohn

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#11
@Sachin thou Bolton did not made Alnico drivers but their Sister Company "Grace" did it.;)

@ Shafic the link you posted is thou of our other FM's but they are Different from these not just in size but in lot of things.:eek:hyeah:

In 8" Size I'll Suggest Iwai Fullrange Speakers which are 4 Ohm [ TL friendly] with a Fantastic 98 dB Sensitivity its 5 dB more than Boston's.:licklips:
 

sarith

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#12
Congrats on your find sann. I had my hands on a 12" nos but there wasn't a pair and the dealer who had it, scrapped it few days later. He had a 12" and a 10" fullrange and a 12" woofer. I bought the woofer.

I had a pair of 6" with blue cone and white whizzer in a ported box paired with philips dome tweeter and connected to a hexfet amp.

Sound wise I would say, it's different. Though I got good money, I kinda regret selling it. Never got my hands on another pair till date.

Well, the more I regret is on not buying a nos big magnet Bolton subwoofer with a rugged green colour cone with larger than normal surround. A police man who actually heard me testing it bought it as soon as I left the shop.
 

yogibear

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#13
Sann, if you are fine with no bass but just best of the midrange, you could put them in open baffle. Just my rough estimate would put them at at least 10,000Hz to 60Hz freq response so the lower end will help decide baffle dimensions.

27 litres could be little less for them in ported box. 1.5 cub ft. should be fine even if TS are not in hand. A 2.75 to 3 dia port and varying lengths from 3 inches to upto 6 inches would help you optimise the lower end.

"Blow the candles" at the port tuning freq is really fun and helpful. I need to try this my bass reflex speakers.

In any case the height, width and depth of the front baffle must be all different.

In those cabinets of yours, you can also try varying the length of the port tube and hear the difference. It may turn out to be the simplest and fastest way to enjoy them.
 
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sachu888

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#14
I recently got these 12" Bolton Full range drivers. They are yet to reached me though.
Any info regarding these drives would be helpful:



Regards
Sachin
 

jls001

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#15
Is there some sort of a full range driver revival happening while I'm slumbering?;)
 

yogibear

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#16
Congrats.

Try some serious TL cabinets with them. Making a little larger TL design will help you experiment the cabinets with anymore 12 inch FL drivers you may have in future. Classic TL design.
 

sachu888

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#18
Thanks, that looks good, but I am looking to make big enclosures as I don't want to use stands for bookshelves.

Regards
Sachin
 

sann

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#20
Sann, if you are fine with no bass but just best of the midrange, you could put them in open baffle.

In those cabinets of yours, you can also try varying the length of the port tube and hear the difference. It may turn out to be the simplest and fastest way to enjoy them.
I have a 8" open baffle ready which I had made for wild burrow betsey drivers, I could try these in that.

The Philips cabinet I am using currently just has a 5x3" rect. slit at the bottom which is covered by a thick cloth from inside, it doesnt have any port tube. I dont know whether all HiQ cabs were like that or I am using something different.
 
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