Max speaker wattage?

[BudM1930]

HELLO
I have a Hi Fi system that includes two JBL speakers in excellent condition.
Unfortunately my Preamp and two Power Amplifiers have failed.
QUESTION: What is the MAX wattage my speakers can safely handle?
Current amplifiers (EICO Model HF35) were 130 watt consumption
with 35 watt output constant and 70 watt output peak.


Speaker #1 was purchased 10/ 1/1956 Model C34 B with D130 speaker
Speaker #2 was purchased 8/30/1958 Model C34 Korina with D130 speaker

Any suggestions for make and model for new equipment for preamp and Amplifiers
(or an integrated amplifier) would be most welcome.

Thank You
Bud M

[Chris Brown]

There won't be a simple answer to this question, as there are many variables. For one, each driver in the system has it's own power handling limitations. The D130 for example, can handle only 75watts, has less than one millimeter of Xmax, and a FS of 40Hz. If you are playing bass-heavy content, you will surpass the abilities of the woofer very quickly. If you are playing content with very little low-end however (or have a subwoofer and use the crossover with your speakers), I have no doubt that the speaker could safely handle considerably more power.

Also understand that there is nothing wrong with having amps that are considerably more powerful than what your speakers can handle. Your amp only puts out as much power as the volume control dictates, and weaker amps can still put out much more power than they are rated for - they simply do it while clipping, which is bad. Most speakers can also easily handle peaks far beyond the average max wattage that they are rated for.

[grumpy]

I think a better question is what power range would be useful?

One watt into those quite efficient speakers would likely be quite loud.

Accounting for likely musical peaks, etc... I expect you never got even
close to clipping those 35w amps. If using tube amps, you probably
had them on 16 ohm taps... if you went solid-state instead (unless
a McIntosh with autoformer), the rating on the amp for a nominal
8 ohms would need to be halved when using a 16 ohm speaker system.

I'm sure there are those with other opinions, but I'd think a nice 35-50w
tube amp would be a fun/vintage-like match.

[BudM1930]

Thanks for the responses.
Can anyone confirm that the speakers are 8 ohm?
Is a spec available?

Regards
BUDM

[Mr. Widget]

Thanks for the responses.
Can anyone confirm that the speakers are 8 ohm?
Is a spec available?

Regards
BUDMSince both of your speakers are from the late '50s they should be 16 ohm. The same drivers were made for decades and later versions had significantly higher power ratings due to improved glues and other changes. Also later versions were offered in 8 ohms.

Most speakers changed from 16 ohm to 8 or 4 ohms during the later '60s and into the '70s as solid state amplification became the norm and most solid state amplifiers handle these lower impedances better.


Widget

[BudM1930]

Thank you for the 16 ohm info.
I was ready to purchase a Yamaha integrated amplifier Model A-S301 having 60 watts/channel, but note that it states 6&8 ohm for the speakers.
The higher wattage Yamaha units A-S501 states 85 watts/channel for 6 &8 Ohm and
The A-S701 states 100 watts/channel for 6&8 ohms.

DO I need a higher wattage unit because I have 16 ohm speakers or do I need to find a new amplifier manufacturer that has a product that will handle the 16 ohm JBL speakers I have?
Thanks for your help
BudM

[BMWCCA]

Why not look inside your cabinets at the rear of the speakers and see what the JBL label says as to 16 or 8 ohm? I'd be likely to bet they're 16, but why not check?

Better question would be how do you know they're D130 if you haven't seen the backs already? And are they simply D130 or do they include a crossover on the back with maybe an 075 as a tweeter?

I've run my 16-ohm D130/075 JBLs for over 60 years starting with Pilot mono tube amp, then Kenwood receiver, then Fischer SA1000, but for the past 50-years I've run Crown amps rated 75 to 90 watts-per-channel, often playing them outside at fairly ridiculous volume levels with no issues.

When I "rescued" the first one from my Dad (he was giving it the Goodwill when he went stereo) I played it from the earphone jack of a tiny ChannelMaster transistor radio. Believe or not, it played very well!

Got any photos of your vintage JBLs you can share?

[JeffW]

Thank you for the 16 ohm info.
I was ready to purchase a Yamaha integrated amplifier Model A-S301 having 60 watts/channel, but note that it states 6&8 ohm for the speakers.
The higher wattage Yamaha units A-S501 states 85 watts/channel for 6 &8 Ohm and
The A-S701 states 100 watts/channel for 6&8 ohms.

DO I need a higher wattage unit because I have 16 ohm speakers or do I need to find a new amplifier manufacturer that has a product that will handle the 16 ohm JBL speakers I have?
Thanks for your help
BudM

Generally speaking, running higher impedance speakers is less of a strain on the amplifier than running lower impedance - your amp will be happier running into a 16 ohm load than it would be if it was a 4 ohm load.

[BudM1930]

Thanks to all for the new inputs.
Have done considerable research and advise as follows:

1) I am confident I have D130 extended range speakers.
Both sales slips (from a reliable store) state D130.
While it is hard to see through front grill cloth one can
see a 15” diameter speaker with a 4-5” silver button in front.

2) I am reluctant to open the back’s 16 screws as there may be some special sealing for sound quality.

3) I did find some old 1950’s file literature that confirms the D130’s are 16 ohms.

4) I am having a major problem finding a new integrated amplifier that offers 16 ohm interface.

5) My need is classical symphonic music. (not heavy rock)

Final question is: For my 16 ohm speakers should I go with a
60 watt amplifier with a 8 ohm output or step up to a
85 watt amplifier with a 8 ohm output?

Look forward to comments.
BudM

[Mr. Widget]

Final question is: For my 16 ohm speakers should I go with a 60 watt amplifier with a 8 ohm output or step up to a 85 watt amplifier with a 8 ohm output?
Your D130s are extremely efficient. They will produce 103dB with one watt of input at a meter's distance so a pair will fill an average living room with an output of over 100dB given one or two watts. A large symphony orchestra will rarely hit this level so I doubt you will need to worry about amplifier output.

Now that said, if your speakers do not have added horn tweeters and appropriate crossovers, your extended range D130s will have little output above about 5KHz. This was considered an acceptable budgetary compromise in the '50s, but generally is not acceptable today.


Widget

[BudM1930]

Thanks Widget

Just curious – The SN for the 1956 purchased C34 with D130 was
14951. Would the factory be able to determine if there were other speakers in the cabinet?

Thanks
BudM

[Mr. Widget]

No, they had a fire and lost their older records. If you post photos of the front and back we can probably sort that out for you pretty easily.


Widget

[BMWCCA]

Just curious – The SN for the 1956 purchased C34 with D130 was
14951. Would the factory be able to determine if there were other speakers in the cabinet?The C34 cabinet had its own serial number that may have had nothing to do with the speaker system installed inside, regardless of JBL records being available, or not. Also, 1956 was the first year the 075 ring radiator appeared in the JBL catalog. I believe that was the year my Dad purchased his 030 system (D130, 075, and N2400) though the N2400 doesn't appear until the 1957 catalog. If you have the original bill of sale and it doesn't show anything but the D130, that's likely all there was!

If you remove the back (there is no sealing other than an interference fit of the wood pieces) you'll be able to see if the cabinet was designed for other speakers. Usually there are other openings cut and then covered with mostly triangular pieces of wood to cover the opening if they weren't used. As Widget said, a photo of the back where the speaker terminals are would tell us a lot. Taking off the back, maybe even more! It might help to shine a flashlight into the grille cloth to help see behind. I you have an 075 you'll have the network/crossover at the rear and the 075 will likely be in an upper corner in the front. If you need help posting photos, we're happy to help with that, too!

[BudM1930]

Hello again

Thank you for the detailed information in your latest posts.
To respond to some of your points, I have posted pictures of my C34 D130 speakers, and notes on my examination after removing the back panels. Sorry the pictures did not give much detail. On the back panel all that is in the little inset at the bottom are two metal terminals. The JBL icon can be seen on the left front screen in the upper right.

It has now been established that I have one speaker (D130) in each cabinet and they are 16 ohm. I have no plans to make any changes to the speakers – as they produced excellent sound output that we enjoyed for some 30 years. After 30 years in mothballs, I now look forward to getting my Hi Fi system up and working again.

I am planning to purchase the Yamaha model A-S301 which has 60 watt/channel output and 8 ohm.

My final assist needed is – considering my speakers are 16 ohm,
should I stay with the A-S301 or step up to the A-S501 which has
85 watts/channel output and 8 ohm to adjust for my 16 ohm speakers?

Your comments on that point would be appreciated.
Regards
BudM

[BMWCCA]

It has now been established that I have one speaker (D130) in each cabinet and they are 16 ohm. I have no plans to make any changes to the speakers – as they produced excellent sound output that we enjoyed for some 30 years. Thanks so much for sharing your wonderful pieces of JBL history!

I don't think I could contain myself from adding at least an 075 tweeter if not an LE175DLH to the system to really make it come alive. But that's likely because I grew up with the 030 system in my house.

[grumpy]

The 60 watter (30w into 16 ohms) should be plenty, even if you goose the bass a bit.

[BudM1930]

I thought the 16 ohm for the D130 was established when I found a piece of literature in my file stating it was 16 ohm.

Did some searching of past posts in this JBL thread looking for more info on the D130. Was surprised by a posting dated 1/28/12 by claytushaywood entitled JBL D130 Impedance and cone question.

In that post, three responders replies would indicate that the D130’s prior to 1966 ( era of my two speakers) were really 8 ohms. If that is true, my amplifier wattage problem is resolved. Comments would be most welcome.

Thanks
BudM

[grumpy]

Impedance can be stated as 'nominal', minimum... or shown as a plot vs frequency such as

76463

Which was claimed to be a D130 in a ported box, and would tend to support a 'nominal' 8-ohms as reasonable.
For a single speaker (no crossover), and solid state amp, the point is somewhat moot...
a 60w (into 8 ohms) amp should be plenty. If 85w floats your boat for whatever reason, it will not hurt anything
any more than overdriving the 60w amp would (e.g., turning the bass way up and expecting the system to
play subwoofer frequencies).

[BudM1930]

Thank you Grumpy

One final question.
I have a new multimeter. One setting is ohms. Searching the web I understand that I may be measuring DC ohms, and that AC ohms may be somewhat higher.

Made several tests on each unconnected speaker at their outside terminals. Left speaker (#2) was constantly at 9.3 ohms. Right speaker (#1) was constantly at 6.2 ohms.

This appears to indicate that both the speakers are 8 ohm, and not 16 ohms. Comments would be appreciated.

Thanks
BudM

[Mr. Widget]

A digital multimeter will typically only measure DC resistance. The DC resistance of a speaker is almost always significantly lower than the nominal impedance. A DC resistance measurement of 9 ohms is typical of a 16 ohm woofer, The 6.3 ohm woofer may very well be an 8 ohm woofer, in any case if you are not planning on adding tweeters and you're just going to run these woofers as they are, I really wouldn't worry about it. It just won't matter what the impedance is. You may need to adjust the channel balance between the two as the one with lower impedance will play louder at the same setting.


Widget

[BudM1930]

Decision time:
Have decided to go with integrated amplifier model A-S301 by Yamaha.

1) Has slightly more power than my failed amplifiers
2) While connecting posts are not marked on my speakers I am assuming black wires are ground and colored wires are Positive. So on my speakers that would be left contact is ground and right contact is positive.
3) While it is still not clear if my two JBL D130 speakers are 8 or 16 ohm, and this amplifier’s max is 8 ohms - so I am going to assume the extra amplifier power is more than enough.
4) I am not planning to add any additional speakers at this time.

I will advise how it turns out after I get it all up and running.
Thanks to all for your comments and patience.

Regards
BudM

[BudM1930]

Hello again

My new amplifier has been installed.
It was a good choice.
Only issue is volume. Range on dial is from 7:00 to 4:00.
Above 10:00 sound is so loud you can not stand it.
So, I will need to watch the volume control carefully.
Everything else is above expectations.

Thanks to all that helped me through this need.
I will be enjoying my great JBL speakers for years to come.

Regards
BudM

[grumpy]

:applaud:Glad you found something that will work and let you listen.