Cornwalls: Where's the Bass? Found it!

[Coloradohiker]

I finally got some K-77's (sixties vintage) installed in my abused Cornwalls and set them up in their temporary home in the basement. I was a little shocked by the lack of bass they put out. I wasn't trying to listen to organ music, but they seem unable to reproduce some of the lower bass guitar notes. I hooked up a couple of different floor standing speakers (including a pair of Klipsch SF-1's) and they all do a much better job on the lower end. I'm not looking for chest pounding bass but I do what to hear the music in its' entirety.

The components in my Cornwall's are K-77 tweeters, K-57-K mids (with the plastic horns), K-33-E Woofers and B-3 crossovers. I don't think that the woofers are original since they have round magnets instead of the square magnets I believe were being used in 1985. That, and the fact that the wires where just twisted on the woofer lugs and I imagine that Klipsch actually soldered them on (Yes, I corrected that!). I also loosened and re-tightened all the lugs on the crossovers & speaker terminals. I tested the resistance and came up the following readings though they might not be accurate since it is a very cheap digital multi-meter.

Tweeters-7.1 ohms

Mids-11.8 & 12.1 ohms

Woofers-8.7 ohms

So, could the lack of bass be caused by the woofers are not being the right vintage? Since the tweeters where blown at least twice and the woofers where probably blown once, could the crossovers be damaged? Or am I just expecting too much bass out of a 52-year-old design?

I appreciate any thoughts you might have.

Alan

[Rudy81]

Something is not right. Cornwalls put out plenty of bass for most of us. I would double and tripple check the connections to the crossover and ensure you don't have the woofers out of phase. Other potential problems may lie in the crossover itself. Crossover experts here might be able to suggest where to go in that area.

[BEC]

I finally got some K-77's (sixties vintage) installed in my abused Cornwalls and set them up in their temporary home in the basement. I was a little shocked by the lack of bass they put out. I wasn't trying to listen to organ music, but they seem unable to reproduce some of the lower bass guitar notes. I hooked up a couple of different floor standing speakers (including a pair of Klipsch SF-1's) and they all do a much better job on the lower end. I'm not looking for chest pounding bass but I do what to hear the music in its' entirety.

The components in my Cornwall's are K-77 tweeters, K-57-K mids (with the plastic horns), K-33-E Woofers and B-3 crossovers. I don't think that the woofers are original since they have round magnets instead of the square magnets I believe were being used in 1985. That, and the fact that the wires where just twisted on the woofer lugs and I imagine that Klipsch actually soldered them on (Yes, I corrected that!). I also loosened and re-tightened all the lugs on the crossovers & speaker terminals. I tested the resistance and came up the following readings though they might not be accurate since it is a very cheap digital multi-meter.

Tweeters-7.1 ohms

Mids-11.8 & 12.1 ohms

Woofers-8.7 ohms

So, could the lack of bass be caused by the woofers are not being the right vintage? Since the tweeters where blown at least twice and the woofers where probably blown once, could the crossovers be damaged? Or am I just expecting too much bass out of a 52-year-old design?

I appreciate any thoughts you might have.

Alan

The woofer should be a 4 ohm and should read a little under 4 ohms when you measure resistance. Those look like Klipsch K-33Es which would be right, but often someone has them reconed and end up with the wrong parts inside. A real common mistake that recone places make is to use an 8 ohm voice coil in them. With an 8 ohm voice coil, you would lose 3db of output from the woofer and the crossover frequency would be messed up.

Bob Crites

[davis419b]

I am curious. In your pic it looks as though there is something gray in the bottom port area of the cabinet. Can you tell me what it is ?

[Coloradohiker]

That would be years of filth and neglect layered over the black paint in the lower ports. There was also a fine collection of mouse droppings on the port shelf paper damping material. At times, I do question the sanity of trying to resurrect these speakers.

On another note, besides the woofers, do the ohm readings look “average” for the other drivres or is the meter I used totally useless?

Alan

[BEC]

Your other numbers look pretty close.

Bob Crites

[Schu]

when I first received my CW's I felt the same as you OP... but then with a little experimentation on the amp settings things changed drastically... and I am still using the OEM crossover.

one other thing I notice, on my CW', is that at lower volume levels, bass is under pronounced, at higher volume levels, they scream bass response.

[Pete H]

Cornwalls produce very nice bass with old drivers or new drivers so I hope you find the problem soon because you're missing the best part of the Cornwall.

[PrestonTom]

A couple of obvious thougts.

1. Is the back panel attached snugly?

2. Any chance that the cabinets are wired "out of phase"?

Fortunately, no one has made the usual comment about needing to upgrade the crossover capacitors to something fancy blah, blah, blah .....

[DizRotus]

"The woofer should be a 4 ohm and should read a little under 4 ohms when you measure resistance. Those look like Klipsch K-33Es which would be right, but often someone has them reconed and end up with the wrong parts inside. A real common mistake that recone places make is to use an 8 ohm voice coil in them. With an 8 ohm voice coil, you would lose 3db of output from the woofer and the crossover frequency would be messed up."

Bob Crites

It seems to me that Bob hit upon the problem and, therefore, the solution. The woofers appear to have 8 ohm resistance where 4 ohm is called for.

The other suggestions regarding proper phase, sealed backs, room placement and even new caps are valid but won't overcome having incorrect woofers.

[PrestonTom]

Well Neil, Bob Crites does make an important point. Whether the impedance on a rebuilt K-33 is correct does need to be double checked.

However, that would be changing the level by 3dB at the crossover point. So there are two issues. According to the OP there was a lack of substantial lack of bass for the lower registers of organ music.

First, -3dB is not a substantial loss.

Second, those frequencies are well below the crossover cutoff frequency.

So, the problem may be a bit stickier .......

[BEC]

Tom, what do you mean by "However, that would be changing the level by 3dB at the crossover point"

In fact, if you double the impedance of the woofer, with the same voltage still applied, it's output goes down by 3db for all of it's range. As for how significant a drop that is, it is about the difference in the bass output we see when comparing a Heresy to a Cornwall. Most would thank that is significant.

Bob Crites

[Coloradohiker]

A few of points:

1) It was not organ music I was missing (I don't own any), just simple bass guitar notes out of something like the Eagles-Out of Eden CD

2) I checked the phasing when I soldered the woofers. Simply switching from left to right channels would reveal if I had some type of phase issues.

3) To illustrate my lack of bass, while listening to my garage system today, I could hear notes that I'm missng from my Cornwalls. My garage system consist of a SanDisk MP3 player, an incredibly cheap Technics receiver (SA-913), and some beat up JBL 2600's

So, in my book, the resistance issue is probably at least some, if not most, of the problem. After researching this forum on the cost of re-reconing my K-33's or getting new woofers to correct this problem, I'm in a quandary whether it is worth the investment ($200-300). I would love to get some of Bob's woofers but since the cabinets need to be reveneered and some new grill made (more $$$'s), it may make more sense just to wait and find a good deal on some Cornwalls in better shape.

Guess I'll just have to sleep on it, maybe for several nights!

[PrestonTom]

Yoou have misunderstood point #2. However, if you feel that the woofers are both wired in the correct polarity, then follow up on BEC's advice.

[PrestonTom]

Bob (BEC), I guess that I am under the impression that there is much more of a difference than 3dB between a CW and a Heresy at the lowest octaves. But it is not worth arguing about.

[Don Richard]

A 3 dB drop on a volume knob is a small change. A 3 dB drop on a crossover passband is very noticeable because it changes the entire balance of the sound. I can easily notice a 1/2 dB change if I adjust my active crossover that amount. I can't directly hear the level difference but the difference in tonality and spectral balance is apparent. Change your woofers to 4 ohm models and you will be very happy with the Cornwall's bass.

[Coloradohiker]

Update

I was really disappointed with the sound of the Cornwalls but couldn't justify spending the money on new woofers considering the overall condition of the speakers. One night while surfing the internet, I realized that I would be staying within 20 miles of Orange County Speakers during a road trip with the foster kids to Southern Califonia (a 4 & 5 year old + 1100 miles = good times). I dropped the K-33-E's off on Monday and the good people at Orange County where able to recone them back to 4 ohms by Friday.

I installed them tonight and all I can say is WOW! Not only are the missing bass notes back but the mid-range is much smoother. I don't know if there where other issues with the woofers besides the resistance (old 8.7 ohm vs new 3.9 ohm), but just having them reconed made a HUGH difference. I can now justify spending the time and effort to refinish them

[DavidF]

Update

I was really disappointed with the sound of the Cornwalls but couldn't justify spending the money on new woofers considering the overall condition of the speakers. One night while surfing the internet, I realized that I would be staying within 20 miles of Orange County Speakers during a road trip with the foster kids to Southern Califonia (a 4 & 5 year old + 1100 miles = good times). I dropped the K-33-E's off on Monday and the good people at Orange County where able to recone them back to 4 ohms by Friday.

I installed them tonight and all I can say is WOW! Not only are the missing bass notes back but the mid-range is much smoother. I don't know if there where other issues with the woofers besides the resistance (old 8.7 ohm vs new 3.9 ohm), but just having them reconed made a HUGH difference. I can now justify spending the time and effort to refinish them

Good ending to this movie. Ain't the internet great? And this community?

[Pete H]

Glad it all worked out for you, enjoy those Cornwalls.

[DizRotus]

Glad you found the bass!

Bob was right. I think I'll save that as a macro for future use.