Modified Cambridge S30?

[Swerd]

A short while back, I remember reading a post from someone who had Cambridge S30 bookshelf speakers. He said he sent one to Dennis Murphy for modifications.

I'm curious. What were the mods? If I know Dennis at all, he probably designed a different crossover that probably made them smoother sounding across the upper midrange.

So, what about those modified S30S? Those speakers are certainly low priced at $215. Depending on what the mods cost, they might be a real bargain.

 

[zieglj01]

A short while back, I remember reading a post from someone who had Cambridge S30 bookshelf speakers. He said he sent one to Dennis Murphy for modifications.

I'm curious. What were the mods? If I know Dennis at all, he probably designed a different crossover that probably made them smoother sounding across the upper midrange.

So, what about those modified S30S? Those speakers are certainly low priced at $215. Depending on what the mods cost, they might be a real bargain.

Well, I guess you are talking about me.
He changed it from a 2nd order acoustic, to a 4th order acoustic
tuned box. He did smooth out the mids, and balanced the over all
sound more. It is not a night and day difference - however, the
difference is there. The upgrade cost is modest, and generous on
his part. Do not expect Salk type sound - however, the drivers are
good.
Here is my take on the mod - from the AVS forum
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For the few who may be interested.
The stock version is still solid, and a winner.

Now the modded version:
OK, from Yo-Yo Ma to Chris Botti, from Gloria Estefan to Queen Latifah,
from Joan Osbourn to Pink Floyd and the Eagles - the modded speakers
are a step up. They are more focused and natural sounding, with more air.
The speakers remain cohesive, and the bass is more level with the mids
and highs. I appreciate the bass more.
I still call them the Little Beast - they no longer sound a little intense at
times, and the slightly smeared sound at times, is gone. They still throw a
forward and wide soundstage, with more depth added. The sound character
has not changed. Some people may consider them bright, with their lively
sound character - however, they will not slap you in the face. They are to
me, neutral. I am more caught up in the music and not the speakers. The
imaging stands out more - singing voices now sound more realistic - the
instruments more revealing.

It is a matter of preference and taste, and as always subjective - however,
for me, it is hard to trump the stock version from $500 down - and hard to
trump the modded, from $800 down. This speaker is an open door, for the
one who wants to hear good sound.

I will add more about movies later.

A big thanks to Dennis Murphy for his love of audio.

 

[Swerd]

Well, I guess you are talking about me. He changed it from a 2nd order acoustic, to a 4th order acoustic tuned box. He did smooth out the mids, and balanced the over all sound more. It is not a night and day difference - however, the difference is there. The upgrade cost is modest, and generous on his part. Do not expect Salk type sound - however, the drivers are good.

Yes, "more focused and natural sounding" is a good description of how his crossovers sound. If he could do that with those inexpensive drivers, they must be pretty good to begin with, especially that 4.5" woofer.

Those cabinets are small. Was it difficult to fit the new crossover parts in?

Did Dennis provide frequency - response curves before and after?

 

[zieglj01]

Yes, "more focused and natural sounding" is a good description of how his crossovers sound. If he could do that with those inexpensive drivers, they must be pretty good to begin with, especially that 4.5" woofer.

Those cabinets are small. Was it difficult to fit the new crossover parts in?

Did Dennis provide frequency - response curves before and after?

Let's just say that mine was used for trial and error, and he and I do
have a good sense of humor. They take up a good amount of space.
So that you will understand, how much bass that they have - this is
one from the stock speaker - which is decent, by a foreign magazine.
You need something good to begin with, to be able to take it up.
http://www.stereo.de/index.php?eID=tx_cms_showpic&file=uploads/pics/Cambridge_S30_LS.jpg&width=800m&height=600m&bodyTag=<body style="margin:0; background:#fff;">&wrap=<a href="javascript:close();"> | </a>&md5=b97c2ff642c381eb246727578f082ff3
And this is the results - and you will need to ignore room bounce down
low - he lives near an airport and has barking dogs, with general home
enviorment. He was not dealing with the bass response, to begin with.
http://www.avsforum.com/avs-vb/attachment.php?attachmentid=209816&d=1303510895

Note - the woofer from the outside of the surround, and inside the frame
basket, is 5" - better than most average size 4 1/2"

 

[Dennis Murphy]

Yes, "more focused and natural sounding" is a good description of how his crossovers sound. If he could do that with those inexpensive drivers, they must be pretty good to begin with, especially that 4.5" woofer.

Those cabinets are small. Was it difficult to fit the new crossover parts in?

Did Dennis provide frequency - response curves before and after?

I've tried to attach the before and after, but it probably won't work. I'll try again if it doesn't. The little Cambridge is quite amazing. Although the crossover is just a "cap and a coil," it's a very well thought out cap and coil. The driver integration is excellent, and the drivers are very high quality. The only problem is a lack of adequate baffle step compensation, which can be seen by the ramped up response of the midrange and treble in relation to the bass. That means that heavily orchestrated material will sound a little too forward and smeared. My mod fixes that problem, and also improves the phase tracking around the crossover region. I simply added a couple of components to the existing crossover and a resistor L-pad to get the tweeter in line with the mids and bass. I mount the extra components on a small board that fits in the bottom of the cabinet, and is fed by the existing crossover which is attached to the input terminal. So space is not really a problem. If by some miracle my before and after plots do show up (naaaaa--they won't), the ragged response below 250 Hz isn't due to the a barking golden retriever or Air Bus 300's headed into National Airport. Those are just the real-life bumps and grinds of floor bounce cancellation and room modes. Beware of any plot (like the one in the foreign magazine) that shows a smooth bass response. They've probably spliced a near-field measurement onto the anechoic response, or just guessed what the response would be. My measurements are done with Praxis, which transitions to actual room response below 250 Hz and reveals how the speaker will actually sound in most normal-sized rooms.

 

[Dennis Murphy]

Sigh. I thought I did it right, but nothing showed up. I'll try to just attached the before plot this time.

 

[Dennis Murphy]

Sigh. I thought I did it right, but nothing showed up. I'll try to just attached the before plot this time.

Excellent. And here's the after plot.

 

[zieglj01]

the ragged response below 250 Hz isn't due to the a barking golden retriever or Air Bus 300's headed into National Airport. Those are just the real-life bumps and grinds of floor bounce cancellation and room modes. Beware of any plot (like the one in the foreign magazine) that shows a smooth bass response. They've probably spliced a near-field measurement onto the anechoic response, or just guessed what the response would be. My measurements are done with Praxis, which transitions to actual room response below 250 Hz and reveals how the speaker will actually sound in most normal-sized rooms.

My bad - OK, I stand corrected.

 

[Swerd]

zieglj01 and Dennis, thanks for the info. Good pictures are worth thousands of words.

I always like to point out what else a good crossover does besides just creating the roll-offs between the woofer and tweeter. See both FR curves below.

In this case, the modified crossover equalizes the midrange by reducing the baffle step (roughly 800 to 2000 Hz) and lowers the tweeter response in general.

The crossover point shifts from just under 2000 Hz in the stock version to about 2300 Hz in the modified version, and the roll-off slopes are steeper. The stock crossover is 2nd order, and the modified is 4th order. Those changes minimized the dip at 2000 Hz, probably caused by the cabinet's diffraction of the tweeter (?).

The woofer's breakup noise (see the blue trace, 4000 to 7000 Hz, in the stock crossover) seems to bleed thru in the stock crossover (black trace). It seems to be better suppressed by the modified crossover.

Stock Crossover

Modified Crossover

 

[zieglj01]

My bad - OK, I stand corrected.

However, it is interesting how bass will, and does bounce in a room
You still need decent bass to begin with, and I enjoy the sound. I
enjoy the modded version - and once in a while the stock version.
The stock one before it was modded.
http://www.avsforum.com/avs-vb/attachment.php?attachmentid=209813&d=1303510727

And I am sure, that the source is playing a part.

 

[Swerd]

However, it is interesting how bass will, and does bounce in a room
You still need decent bass to begin with, and I enjoy the sound. I
enjoy the modded version - and once in a while the stock version.
The stock one before it was modded.
http://www.avsforum.com/avs-vb/attachment.php?attachmentid=209813&d=1303510727

And I am sure, that the source is playing a part.

Did you find that the modified crossover made the bass seem to sound better or louder compared to the stock version? The crossover does nothing to those frequencies, but by taming to the too-prominent midrange, it might make the bass seem louder.

 

[zieglj01]

[QUOTE=Swerd)The crossover point shifts from just under 2000 Hz in the stock version to about 2300 Hz in the modified version, and the roll-off slopes slopes are steeper.
The woofer's breakup noise (see the blue trace, 4000 to 7000 Hz, in the stock crossover) seems to bleed thru in the stock crossover (black trace).
It seems to be better suppressed by the modified crossover.
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Hi Swerd,
If you want to know the difference - then play Chris Botti, Live in Boston
on Blu-ray. Also with other sources - even Piano, Guitar, Saxaphone, the
Flute and Violin, and Female voices, sound more clear and defined.
I for one, like the way the tweeter and woofer are placed on the baffle.
This was the only 1st order electrical crossover speaker, that I did really
enjoy. If I did not like it to begin with, then I would have saved me some
money, with the expense that I went thru - to purchase another pair, and
send it to Dennis. Also, if it did not have good bass, it would have stayed
in Texas. The speaker plays below 80hz in my listening area, and is a little
beast. It is 12" from the back wall and I sit 9 1/2 feet back.

 

[zieglj01]

Did you find that the modified crossover made the bass seem to sound better or louder compared to the stock version? The crossover does nothing to those frequencies, but by taming to the too-prominent midrange, it might make the bass seem louder.

The Bass notes are the same - things are overall more balanced. The
bass was still clear and defined in stock form. It seems like Cambridge
believed, that more people would place it on a shelf and not stands.
This speaker has good bass definition, and is not one note or boomy.
With the crossover mod - I would make sure that they are on stands.

 

[Dennis Murphy]

The Bass notes are the same - things are overall more balanced. The
bass was still clear and defined in stock form. It seems like Cambridge
believed, that more people would place it on a shelf and not stands.
This speaker has good bass definition, and is not one note or boomy.
With the crossover mod - I would make sure that they are on stands.

Cambridge describes these pupplies as "stand mounted" monitors, but they probably do sound better on a table. And my reworked crossover definitely assumes they will be stand-mounted.