Hi guys
as the title says i am currently fascinated with the jbl studio monitors and have decided to build a clone of the 4435 series which was pretty much used to mix most of the 80 rock music we listen to and from what i understand the most popular of jbl studio monitors of there time
it is identical in size but i have had to use 2225 drivers for bass/mid instead of 2234
the 2426 horn is time aligned with the 2225 below it and is crossed at 1000hz
the lower left 2225 is brought in under 100hz only so it is essentially a 2.5 way
i have all the crossover diagrams and just need to buy the adjustable l pads
i still have to finish the insides and work out the crossovers which i,m hoping you guys can help with
cheers Sheafer
as the title says i am currently fascinated with the jbl studio monitors and have decided to build a clone of the 4435 series which was pretty much used to mix most of the 80 rock music we listen to and from what i understand the most popular of jbl studio monitors of there time
it is identical in size but i have had to use 2225 drivers for bass/mid instead of 2234
the 2426 horn is time aligned with the 2225 below it and is crossed at 1000hz
the lower left 2225 is brought in under 100hz only so it is essentially a 2.5 way
i have all the crossover diagrams and just need to buy the adjustable l pads
i still have to finish the insides and work out the crossovers which i,m hoping you guys can help with
cheers Sheafer
Attachments
after a little research am i right in assuming i have to halve the capacitance and double the coil to keep the same crossover point when going from 8 to 16 ohm drivers ?
cheers Sheafer
cheers Sheafer
Maybe that's what you would like to hear...
Sometimes works as a starting point, others not close to that. (Certainly not for monitors.)
Best bet is to model them with real/spec data. 😀
Good replacements of the JBL 2234H:
TAD TL-1602
Altec 416-8B
Beyma SM115/K
JBL Thiele/Small Parameters [PDF]
TAD TL-1602
Altec 416-8B
Beyma SM115/K
JBL Thiele/Small Parameters [PDF]
Hi Inductor
the tad tl 16 drivers are exactly what i would use if i was flush with cash but ...
the 2225h are very good drivers and will only give up a little on the low end compared to the 2234 and will be at least as good up high, i will need to tune the boxes a little higher but they should kick ar@#
i have also decided to fit 8 ohm diaphrams to the 2425 i have so they will be identical to the original (i,m hoping this can be done)
i can use pcd to fine tune the design after and later will recone the 2225 to 2234 making all the drivers the same
cheers sheafer
the tad tl 16 drivers are exactly what i would use if i was flush with cash but ...
the 2225h are very good drivers and will only give up a little on the low end compared to the 2234 and will be at least as good up high, i will need to tune the boxes a little higher but they should kick ar@#
i have also decided to fit 8 ohm diaphrams to the 2425 i have so they will be identical to the original (i,m hoping this can be done)
i can use pcd to fine tune the design after and later will recone the 2225 to 2234 making all the drivers the same
cheers sheafer
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If you are doing simulation there's no need for changing 16R's to 8R's to upgrade/calibrate the crossover.
Those woofers look like a suitable replacement. The key is the higher sensitivity (vs. the 4430 woofers) which gives the right up tilt for 2 1/2 way operation. 97 is good.
Keep the same crossover topology and you should be good, although you will want to adjust some values for minor response differences. The biamping componenets can go, obviously.
Nice looking cabinets. Should be a good project when done.
David S
Keep the same crossover topology and you should be good, although you will want to adjust some values for minor response differences. The biamping componenets can go, obviously.
Nice looking cabinets. Should be a good project when done.
David S
Thanks for your advice guys
can you offer any advice on changing the crossover to suit the 16 ohm 2425j vrs the 8 ohm 2425h the crossover is set up for Dave ?
am i correct in assuming i just double the mh and halve the capacitance
also how will this affect the shelving circuit the crossover contains and also the lpads which are 30 and 8 ohm
looking at the crossover i would halve c11 and double l2 correct ? i think the .1uf are bypass caps so would stay as is
i think c9 and l1 are part of the shelving circuit and i am not sure how using a 16 vrs 8 ohm driver would affect these
cheers Sheafer
can you offer any advice on changing the crossover to suit the 16 ohm 2425j vrs the 8 ohm 2425h the crossover is set up for Dave ?
am i correct in assuming i just double the mh and halve the capacitance
also how will this affect the shelving circuit the crossover contains and also the lpads which are 30 and 8 ohm
looking at the crossover i would halve c11 and double l2 correct ? i think the .1uf are bypass caps so would stay as is
i think c9 and l1 are part of the shelving circuit and i am not sure how using a 16 vrs 8 ohm driver would affect these
cheers Sheafer
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In general you can scale all components by doubling L and halving C but the L pads may present a challenge. Components c9 and l1 are a series resonant that gives CD horn correction. Basically a 6dB per Octave rise to 15 kHz. Yes, bypass caps don't need to be doubled and can be omitted if your cap quality is good.
Getting full level at 15k was a challenge on the 4435 (96 dB sensitivity vs the 93 of the 4430), so having a 16 ohm compressiond driver will fight you on that.
look up the AES paper for some details on the design (Improvements in Studio Monitors, David Smith, Don Keele, John Eargle)
Regards,
David
Getting full level at 15k was a challenge on the 4435 (96 dB sensitivity vs the 93 of the 4430), so having a 16 ohm compressiond driver will fight you on that.
look up the AES paper for some details on the design (Improvements in Studio Monitors, David Smith, Don Keele, John Eargle)
Regards,
David
Link to the paper Dave referred to:
http://www.diyaudio.rs/JBL/JBL - Im...ker Systems (Smith, Keele, Eargle) (1983).pdf
Nice job on the speakers!
Kind regards,
Steve
http://www.diyaudio.rs/JBL/JBL - Im...ker Systems (Smith, Keele, Eargle) (1983).pdf
Nice job on the speakers!
Kind regards,
Steve
Yeah, cabinets look pristine. Nice job.
(I don't stop looking at them, what is going on?!)
edit: ah! left tweeter is not in horizontal position (Trompe-l'œil). 😀
(I don't stop looking at them, what is going on?!)
edit: ah! left tweeter is not in horizontal position (Trompe-l'œil). 😀
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Thanks to all for your advice so far
especially speaker David who,s paper originally convinced me to try this design
i am very gratefull to have his advice on this project
yes Inductor those horns are a beautiful shape !!!!
cheers Sheafer
especially speaker David who,s paper originally convinced me to try this design
i am very gratefull to have his advice on this project
yes Inductor those horns are a beautiful shape !!!!
cheers Sheafer
Beautifully finished !
Have any pictures of the inside ?
PS. you have to change those wheels, look too domestic 😀
.
Have any pictures of the inside ?
PS. you have to change those wheels, look too domestic 😀
.
The impedience of the DR8 diaphragm is 10 ohms
The impedience of the DR16 is only marginally higher
I have been in the same scenario before. All you need to do is shunt the driver with a resister, try 20 ohms 15watt and continue with the same values.
The network values are optimised for the CD equalisation.
The impedience of the DR16 is only marginally higher
I have been in the same scenario before. All you need to do is shunt the driver with a resister, try 20 ohms 15watt and continue with the same values.
The network values are optimised for the CD equalisation.
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What I mean is don't mess with the RC values, just shunt the driver with a 20 ohm resister
DR8 is the 8 ohm diaphragm
The measured impediance plot of labelled 8 ohm driver its really about 10 ohms and the 3135 network is designed for that. So you can modify the 16 ohm labelled diaphragm by shunting it with a 20 ohm resister.
DR8 is the 8 ohm diaphragm
The measured impediance plot of labelled 8 ohm driver its really about 10 ohms and the 3135 network is designed for that. So you can modify the 16 ohm labelled diaphragm by shunting it with a 20 ohm resister.
g,day all
dam Macka i saw your post after buying a pair of new 8 ohm diaphrams so too late
any way they are fitted and i have ordered the crossover components from PE so i should be ready by the end of this week
i am also undecided about the wheels
anyway i will take some pics of the inside and report back once i start building the crossovers
can any one shed any light on the purpose of the 4 x 67r in parralell on the .5 woofer?
cheers Sheafer
dam Macka i saw your post after buying a pair of new 8 ohm diaphrams so too late
any way they are fitted and i have ordered the crossover components from PE so i should be ready by the end of this week
i am also undecided about the wheels
anyway i will take some pics of the inside and report back once i start building the crossovers
can any one shed any light on the purpose of the 4 x 67r in parralell on the .5 woofer?
cheers Sheafer
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