Rebuilding a Paragon

[jcdahl]

I am in the process of rebuilding a Paragon. it is a 1970 vintage with LE15As. I noticed there is no accoustic damping material in side the woofer chamber. Is this correct? Or should I put in some acousta stuff? The Bass seems rather "Boomy" although I have a lousey listening area in the shop where I am rebuilding it. The Speakers were all perfect, but the cabinet was beat up. So I have completely re-veneered it and it looks beautifull. Now I am trying to get it to sound as best I can.

Thanks
JCD

[Maron Horonzakz]

No acoustic material was used in my PARAGON & none is needed.

[Guenter]

No acoustic material was in my Paragon's woofer enclosure either.

[Mr. Widget]

Never having heard a Paragon, (I am deeply envious guys!) I should probably keep my mouth shut. Have you
replaced the surrounds or had the LE15As reconed? If they are original, they will most likely not be working
properly.

The other point is that in my experience when I fire up a new system in my shop, they are almost always
disappointing sounding. I realize the Paragon is quite a physical presence but to evaluate it you should take it to
your listening room.

[boputnam]

Originally posted by jcdahl
The Speakers were all perfect, but the cabinet was beat up.

Hey, jc...

Widget's onto something, here. Can you give us history of the drivers (what you know of it...) and maybe post some pics of the LF's (Audiobeer would like to see your woodwork, anyway... )?

[Guenter]

[QUOTE]Originally posted by Mr. Widget
Have you replaced the surrounds or had the LE15As reconed? If they are original, they will most likely not be working properly.

Most definitely true. When I got my Paragon it sounded absolutely dreadful and sure enough the surrounds were stiff and not much below about 80 Hz came out. The previous owner had replaced the LE15's with other speakers in order to obtain more bass and JBL advised me to buy some subs if I wasn't happy with the bass (yeah right my wife with Paragon and Subs
in the livingroom ) note, they never once mentioned checking the surrounds.
Checking their 'time' alignment, turned out that the mids and tweets were nicely in sync, but the woofers were significantly delayed wrt the mids

re being jealous. Don't be! personally even after I had them working correctly I was not particulary enamoured with them for anything other than classical music. I liked their rather diffuse but, I think realistic, presentation of the orchestra. 'Wall of sound' comes to mind. For soloists or small jazz groups, not so good. I sold them for CAN $5000 in '89 to Japan but was happy to do so since I got them for $3000 6 months earlier.
What a difference the internet now makes.

guenter

[Mr. Widget]

[QUOTE]Originally posted by Guenter

re being jealous. Don't be! personally even after I had them working correctly I was not particulary enamoured with them for anything other than classical music. I liked their rather diffuse but, I think realistic, presentation of the orchestra. 'Wall of sound' comes to mind. For soloists or small jazz groups, not so good. I sold them for CAN $5000 in '89 to Japan but was happy to do so since I got them for $3000 6 months earlier.
What a difference the internet now makes.

guenter

Oh, I don't want them for "High Fidelity" listening. I have plenty of other speakers for that. I just love them as a piece of functional sculpture and as an icon of an era.

Widget

[jcdahl]

Thanks for the great responses.... The LE15As were reconditioned with new surrounds (great Job by an east coast speaker shop) the 375s and 075s have been tested and are perfect. I am not sure of the Xovers. I have to set up a test jig and make sure they are working properly (Caps are 34 years old)

One of the horns has the gold paint flaking off so I am trying to find a good paint match to repaint the gold. After I repaint the horn faces, I will re assemble it and take some good Photos to post on line. I am thinking of selling it and finding another to restore.

I am sure the sound will be vastley improved when I get them Home. My shop is 25 ft wide x 40 ft long x 10 ft high with tile floors and bare walls. I think the whole room resonates at about 100 to 400 HZ. A great place to work but, a bad place to listen.

Thanks again fro the response.
JCD

[jcdahl]

Hi again;
Some more ramblings.... I used to be a JBL dealer in Seattle(1959-1960) and sold several Paragons. In those days they sold for $1,850 to $2,150. I couldn't afford one of my own in those days. For many years I had planned on building one but I lost the plans in one of my many moves. Finally I found one that I could afford. Now I have to find room for it at home ( I already have four Olympus systems. two S8s and Two S7Rs along with a 9 foot wide Home brew System with LE10s and LE30s.) My wife thinks she is living in a JBL museum.

JCD

[whgeiger]

[QUOTE]Originally posted by jcdahl
)snip( I noticed there is no accoustic damping material in side the woofer chamber. Is this correct? Or should I put in some acousta stuff? The Bass seems rather "Boomy" although I have a lousey listening area in the shop where I am rebuilding it. )snip(


JCD,

A 1" thick felt lining applied to the back-box walls should help smooth out response in the upper octave (250-500 Hz). Otherwise, using stuffing will have a negative effect on low frequency performance.

Regards,

WHG

[Maron Horonzakz]

I recommend NOT putting felt lining. This is simmiler to the compression chamber in the Klipschorn. Lining is not needed. Check impenence of woofer in chamber.

[johnhb]

no material in mine. did sound bad in room without carpet. Move it to a carpeted room before touching anything.

[whgeiger]

Originally posted by Maron Horonzakz
I recommend NOT putting felt lining. This is simmiler to the compression chamber in the Klipschorn. Lining is not needed. Check impenence of woofer in chamber.

MH,

Facts of the matter follow:

1) Because a commercial loudspeaker does not have a particular design feature, is an insufficient basis to demonstrate that it “is not needed”. Doing what others do is only a sufficient explanation for why more than one dead sheep may be found at the bottom of cliff. Here it boils down to the non-acoustic issue of who is doing the needing and who is doing the providing. When both rolls are not filled by the same person, then what “is not needed” tends to change considerably. Here in the two party model, what “is not needed” is a significant loss in profit margin.

2) A back-box is not a compression chamber. The latter is also called a front chamber. The compression taking place there is characterized by the ratio of effective radiating area of the driver to that of the throat exit into the horn. It has nothing to do with lining in the back-box (rear chamber).

3) Back-box impedance (and particularly the compliance component) becomes an issue, as horn cut-off frequency is approached, not the other way around. Here a different ratio rules; it is between the compliance of the driver and that of the air trapped in the back-box that matters.

4) At these lower frequencies, the effect of the lining is negligible. The opposite is true for loose fiber filling, however.

5) This is not the case when wavelength becomes comparable to back-box dimensions. Here you want to create anechoic condition within the enclosure to suppress the formation of standing waves. In this setting, that is the sole purpose of the lining, no other.

6) Both the Klipsch and Ranger horns exhibit irregular response at the upper end of their pass-bands, partly due to the absence of the recommended lining in their back boxes.

7) Of course, there are other issues surrounding the irregular upper frequency response; but to address them requires major changes to the enclosure design and or the driver used.
These issues are not within the scope of this thread, where tweaking of an existing driver/enclosure is being addressed.

Regards,

WHG

[Maron Horonzakz]

I stand by my recomendation. As JBL to me when I built my PARAGON. I also stand by PAUL KLIPSCH,s papers on this same subject. When I questioned him about the lack of lining in the chamber. He presented me with his BULLSHIT button. As I present it to you.

[whgeiger]

Originally posted by Maron Horonzakz
I stand by my recomendation. As JBL to me when I built my PARAGON. I also stand by PAUL KLIPSCH,s papers on this same subject. When I questioned him about the lack of lining in the chamber. He presented me with his BULLSHIT button. As I present it to you.

MH,

The tack your taking here is called "name dropping".
You certainly do deserve the ‘button’ you got.
It is your 'monkey' and you get to keep it.

WHG