Vintage JBL C-38 Driver question

[athan]

Hi all,

My father bought a C-38 with the 030 driver complement (D130, 075 tweeter and N2400 crossover) back in the 50's as a mono setup. A decade later when he moved to stereo, the C-38 was relegated for use as an end table in my parent's living room for over 50 years (my mom liked the wood finish and didn't want to part with it!). When we sold my parent's home several years ago, I rescued the C-38 and found that once I rebuilt the crossover, it actually worked and sounded pretty good. Ever since I've been on the hunt for a mate so I could run it in stereo.

As luck would have it, I bought an Ampeg B-15S bass flip-top amplifier/cab and imagine my surprise when I opened it up and instead of finding the Altec 421A that was supposed to be there I found a D130F speaker. I measured the impedance on both the D130F and my original D130 and both seem to be 8-ohm speakers (the D130 tag lists it as 16-ohm and the D130F tag lists 8ohm). The plan is to run these speakers off of a MAC 1700 receiver as a vintage stereo system (also bought a second 075 and N2400).

Can I use the D130F as a HiFi speaker for my stereo pair? Any issues with running the D130F using the N2400 crossover? Assuming this is technically possibly, are there any sonic benefits to seeking out a regular D130 instead of using the D130F in one cab?

Appreciate any insights here and I'm excited to finally get this system put together. Only wish my father was still alive to hear his first speaker come back to life in stereo.

Andrew

 

[Nyjblbob]

As with any pair of speakers used for Stereo,
They have to be matched, as Both 8 or 16 ohms.

 

[athan]

Sorry I should have clarified that despite the different tags, both speakers measure as 8ohm speakers (~6ohms using my digital multi-meter). In reading other threads, several have commented that all D130s are 8ohm and that JBL labeled some early ones 16ohm and then changed the label to 8ohm with no physical changes to the driver. This could explain the mismatch in labels.

 

[Johnny_Law]

You can find quite a bit about the D130 vs. D130F if you search the internet, but in short the "F" is supposedly for "Fender", so the D130F was a regular D130 with a slightly widened VC gap and goop applied to the surround in order to toughen it up for guitar use.

People say that there is a TINY but insignificant decrease in sensitivity with the F, and that the frequency response is functionally identical.

If it were me in your shoes, I would just use your 075 and N2400 and run them with the D130F in another C38 cabinet and see if you can hear any differences (seems like you probably won't, at least from the internet search). I have 030 loads in my C40 cabinets and love them, but I've never heard a D130F.

 

[GordonW]

IIRC, Harvey Gerst (who was responsible for the changeover from the D130 to the D130F), said that there's like a 1/2dB difference in average sensitivity, between the original D130 and the D130F.

That said- the variation in sensitivity between two woofers on the same assembly line, could have been as much as a 1dB in those days. So, 1/2dB is well within that normal range.

And, it's VERY difficult to hear a difference of below 1dB in sensitivity. Especially in a real-world room, where the effective "gain" of one speaker vs. the other, can be significantly affected by the room itself. I'd be willing to bet, that the most that might be required, would maybe be to swap one speaker/cabinet from one side to the other in the room, to get things to balance out.

Regards,
Gordon.

 

[BMWCCA]

The D130 doesn't really produce a lot of low-end. I started with basically the same as you but my Dad had a his 030 in a C35 clone cabinet. Even in the larger cabinet the bass wasn't all that great but it was better than any of my friends had. When I later found another 030 in a C37 I kept them as a "pair" for years and still have them today. I now have two empty C35s from JBL waiting to be repopulated along with an LE1754DLH pair I've been hoarding just for that purpose. If I were you, I'd build two new cabinet along the larger dimensions of the C35 or C37 to give the D130A a chance to be as good as it can!

 

[athan]

IIRC, Harvey Gerst (who was responsible for the changeover from the D130 to the D130F), said that there's like a 1/2dB difference in average sensitivity, between the original D130 and the D130F.

That said- the variation in sensitivity between two woofers on the same assembly line, could have been as much as a 1dB in those days. So, 1/2dB is well within that normal range.

And, it's VERY difficult to hear a difference of below 1dB in sensitivity. Especially in a real-world room, where the effective "gain" of one speaker vs. the other, can be significantly affected by the room itself. I'd be willing to bet, that the most that might be required, would maybe be to swap one speaker/cabinet from one side to the other in the room, to get things to balance out.

Regards,
Gordon.

Thanks Gordon. From what you cite above, I doubt I'll notice an audible difference. Good call on evaluating the room acoustics/placement as well. I may pair these with a McIntosh MC2505 amplifier, which has a separate gain knob for each channel -- these have been very useful in the past to tame some acoustical imbalances in the various rooms I've used that system in.

 

[athan]

The D130 doesn't really produce a lot of low-end. I started with basically the same as you but my Dad had a his 030 in a C35 clone cabinet. Even in the larger cabinet the bass wasn't all that great but it was better than any of my friends had. When I later found another 030 in a C37 I kept them as a "pair" for years and still have them today. I now have two empty C35s from JBL waiting to be repopulated along with an LE1754DLH pair I've been hoarding just for that purpose. If I were you, I'd build two new cabinet along the larger dimensions of the C35 or C37 to give the D130A a chance to be as good as it can!

I fully agree on the lack of low-end for the D130 in the C38. I think you're right about cabinet volume being a significant factor in bass reproduction for the D130. The Ampeg bass guitar cab that contained the D130F was significantly bigger than my C38 enclosure (i.e. ~30% visual guess) and I thought that it sounded plenty deep for a musical instrument speaker. In fact, that's why I was so surprised to see a D130F in there when I opened it up!

I wish I had room for a set of larger cabs, but my original C38 has sentimental value as it was my father's so I can't part with it, and I have no room for more speakers. What I may consider doing is adding a small sub to "enhance the bass" for my C38s (i.e. 3-way "external solution" with the D130s providing a nice mid-range). I know this is blasphemy for some, but I've successfully used subs with smaller speakers with great results.

Something like an REL Classic 98 in walnut might be a nice addition that fits with the natural wood of the C38 cabs.

Classic 98 Subwoofer | REL Acoustics

Mid-Century modern stereo gear exudes a unique, timeless charm. Perhaps it's the raw honesty and authenticity. We revisit this golden age, bringing you a modern interpretation of classic RELs, complete with a rich, natural walnut veneer and a potent 300W amp driving a down-firing 10” driver.

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