Just for grins - 3110 and 3105 Xovers..

[HenryW]

I am a bit intrigued about using a 3110 as the LF Xover and taking the HF out to a 3105 with the LF side then going to a 2425H and the HF going to a 2404H. Knowing I have to compensate for the 16ohm anticipated and 8ohm actual (spec stuff - knowing that measurement will give me something near that), what is the major problem you folks see in this type of setup?

[HenryW]

JBL pro site has two different specs on the 3105. Was there a difference in earlier models or are one set of specs accurate?

One shows HF out for 8 ohms. The older (apparently) spec shows HF out to 16 ohms.

[4313B]

Post the links you are looking at...

[HenryW]

These are at the JBLpro site under vintage products. The first is
http://www.jblpro.com/pub/obsolete/Frequency_Dividing_Networks1.pdf

This sheet also has the 3106, 3110, 3120, etc. Page two is where the chart identifies specs of the Xover and shows a HF impedence of 16 ohms.

The second is here:

http://www.jblpro.com/pages/pub/obsolete/3105-3115A.pdf

This sheet also has the 3110A, 3120A, etc. The specs are on the second sheet showing HF as 8 ohms and further labels the 3105 as for a certain group of tweeters that include the 2404 I will be working with.

[4313B]

The only problem I see you potentially having is running the 2425H instead of the 2425J.

[Mr. Widget]

What woofer will you be using? The 3110 has an autoformer to lower the output of the HF section and isn't all that flexible in application.

[4313B]

This might be helpful -

http://audioheritage.csdco.com/vbulletin/showthread.php?s=&threadid=459&highlight=3105

http://audioheritage.csdco.com/vbulletin/showthread.php?s=&postid=14969&highlight=3105#post14969

[HenryW]

Mr. Widget - the LF is a 2225H (2205 reconed by JBL with 2225). My original thread on the project is here:

http://audioheritage.csdco.com/vbulletin/showthread.php?s=&threadid=2192

Giskard - thanks for the schematics. They is enough info there for me to noodle on for a bit and try to figure some modifications.

As to the 2425H - my seat of the pants was to add series resistors - Am I being too simplistic?

Thanks to all for putting up with my clearly novice questions, but I do eventually get things pounded through an increasingly thick skull. Xover modification is a challenge that I don't plan on losing...It may mean I have to build my own since I have clearly chosen drivers that JBL didn't put together (more nights of the lovely wife saying 'What time did you get off that computer last night?'). I would just like to keep a JBL 'look' since I am so far into them on this gig.

[4313B]

"As to the 2425H - my seat of the pants was to add series resistors - Am I being too simplistic?"

If you already have everything on hand you might want to hook it all up "normal" first. Start looking for solutions if it sounds "wrong".

[HenryW]

Yep - in that quasi-sleep stage last night I came to the same conclusion. I am going to build with the two Xovers then test (I'll have to borrow equipment or take to a friend's shop). It looks like I have enough info (thanks again for the schematics) to convince me that changes needed can be made with some relative ease - that was an important step.

I will have one test box where I can change the horns and see what happens with a 2370 vs a 2345 (I think the 2370 will win, but since it is in hand I should try - don't want to miss a possibility - it could be a surprise).

Thanks again...