View Full Version : 4315 references thread

05-29-2007, 08:32 AM
This thread is an index to various other threads and references on the early JBL 4-way monitors.

From the L250 profile on this site:
The four-way concept allows for very wide dynamic range since the individual drivers are called on to reproduce a relatively narrow range of frequencies and therefore the overall system can handle more power. Within their narrow range, each driver can be fine tuned in the network design to result in an inordinately flat response ...a 4-way concept that Greg Timbers pioneered in the 4315 monitor of 1974. (http://www.audioheritage.org/html/profiles/jbl/l250.htm)

The 4315 is probably the smallest of the "big" 4-way Studio Monitors at 33 5/8 x 20 1/2 x 12 1/2 and weighs "just" 95 lbs!

According to a post from Riessen (http://audioheritage.org/vbulletin/showpost.php?p=170283&postcount=2)the very early 4315 are recognizable by the dual ports down low on the baffle. You seldom see this model and they are quite rare. The later versions (4315A and 4315B) had a single port (as below)

4315A image below (http://audioheritage.org/vbulletin/showthread.php?t=7532) courtesy of Subwoof (nice looking speakers!)

Middle left shows a set of 4315 drivers - photo probably from a Japanese 43xx fan site

Middle right is the early 2 port style 4315 sold via ebay in May 07

05-29-2007, 09:14 AM
There were 3 versions of the series, the original 4315, the 4315A, and then later the 4315B.

In a previous thread, Giskard posted this pricing information -

"The oldest Pro price list I have only goes back to April of 1977 -
http://audioheritage.csdco.com/vbulletin/showthread.php?t=349&highlight=studio+monitor+pric e+list" (http://audioheritage.csdco.com/vbulletin/showthread.php?t=349&highlight=studio+monitor+price+list)

Thanks, Giskard!
(HJ - Note the prices for the 4315 started at $771 in April 1977 and went to $1128 for the 4315BWX in April 1981)

Here is a Link to 1977 4315 brochure (http://www.lansingheritage.org/html/jbl/specs/pro-speakers/1977-4315.htm) in the Library section of this website.

Link to 4315 brochure at JBL Pro - http://www.jblpro.com/pub/obsolete/4315.pdf

Link to 4315B brochure at JBL Pro - http://www.jblpro.com/pub/obsolete/4315b.pdf

Here's a driver chart from JBL Pro Division - I modified it slightly to display the major 4-way Monitor systems all on the same page

05-29-2007, 09:15 AM
Quoting a complete post from Greg Timbers on 02/23/2006 (original here:
http://audioheritage.org/vbulletin/showpost.php?p=94921&postcount=12) (http://audioheritage.org/vbulletin/showpost.php?p=94921&postcount=12)

4315 vs XPL200

Giskard asked me to comment on this thread as I come from a position of knowing both speakers very well.

The 4315 is a very compact, high power 4 way studio monitor. It was designed around in-wall mounting although they are very rarely used that way. Its strong points are a very powerful and fast woofer (doesn't go real deep however) and a killer midbass unit. The LE5 is a little aggressive but quite lively. The good news here is that the VC alignment on the LE5 and the 2405 is nearly perfect so none of the combing that usually occurs with the 2405 used with horn drivers happens.

The 4315 requires that the HF and UHF L-Pads be turned down considerably below the "0" setting or the system is too bright. With that said, it is very dynamic, detailed and quite good tonally. It is still one of my favorite spaekers.

The XPL 200 has a killer midrange in the 091 or 093. The blend between the HF and UHF is really good as they are in the same plane and identical materials. The 2214H was chosen to give good bass extension and it does just that. Unfortunately compared to a 4" VC 2203, it doesn't have the kick or dynamics. The biggest weak link inthe XPL 200 is the mid bass unit. It uses a filled polypropylene cone with a vinyl surround. It is very smooth but it is too warm and "fluffy" sounding due to the poly collasping under drive. Another weak point is the LF/MF passive crossover topology. It was done to allow bi-amping with a simple toggle switch. The 4315 crossover uses a higher order crossover at that point and has a much more complicated switching circuit. That means money which I didn't have in the XPL.

I would only expect about 1 - 1.5 dB difference in 2.83v sensitivity in favor of the 4315. If both systems are adjusted to similar HF response (i.e. turn down the 4315 a little) and overall sensitivity I would expect the following:

The 4315 should be more dynamic and detailed below 800 Hz - 1000 Hz. The XPL200 should kick butt above that. The XPL will be considerably more 3-dimensional due to the narrower baffle and neoprene covering. It could be hard to choose between them as they are both quite nice but just different. Bi-amping the XPL really brings it to life by fixing the crossover problem and taking the LF inductor out of the path for the 2214, but a special drive slope is required to do the job correctly. The DX1 is ideal and was developed exactly for that purpose. The 4315 benefits substantially from bi-amping as well.

I'm pleased to see that both are still around and bringing pleasure to people.

05-29-2007, 11:19 AM
Link to 3114 Crossover network (for 4315) at JBL Pro (dated 07/74)

Link to 3114A Crossover network (for 4315A & B) at JBL Pro (dated 3/76)

Also see Techbot link here -
http://www.audioheritage.org/vbulletin/showthread.php?t=10615 (http://www.audioheritage.org/vbulletin/showthread.php?t=10615)

05-29-2007, 11:26 AM
Here's a recent ad on ebay that seems to have fired up some interest in this model

05-29-2007, 11:27 AM
This is designed to be a longer term references to other resources here and outside on the web. We are trying to keep the signal to noise ratio high.

To keep the thread "on topic", please give me the next few days before posting ANY replies or comments here.

Your on-topic images, information, insights and links are most welcome and I'll give you credit for your contributions.

Your PMs are most welcome.

Thanks for your help!

Heather James

05-29-2007, 05:06 PM
And this is where they can end up...

05-30-2007, 07:55 AM
Macaroonie's 4315As are worth chasing down the original thread to glean the nuggets of this international design - XO help from Giskard, ports made from "Balvenie 12 year old Doublewood whisky bottle tubes" - really ... go read the thread for yourself!

4315a's in a new ballgown