Thiel Owners

This journey I am talking with the CS3.7 is hitting rough patch after rough patch. It is not really bugging me though, a little interesting actually. Learning a ton of stuff about audio. My background is as an expert listener of music. :)

Today I did the REW software measurements of the 2 speakers. The new issue is that the Sound Pressure Level graph of my LEFT and RIGHT speaker are not identical. There is sufficient divergence between the L and R to indicate that something is wrong. This divergence occurs at 1K level. I got this feedback from the Audio Engineer who analyzed the data.

So I am going to learn how to interpret the REW software correctly and measure my KEF LS50s myself to eliminate the very new Benchmark gear as the culprit. I am almost 100% certain this less than 6 month old brand new Benchmark gear is flawless.

I have an idea what the issue is but will not speculate here until I speak with Rob Gillum tomorrow morning. If my hypothesis is correct it will cost me some funds to fix it.

I should note that both COAX drivers are in phase now and to my ears the system sounds great. However, I cannot move forward with the DRC until the SPL graphs are almost identical.

BTW - I was just playing The Boy’s Doin’ It - Hugh Masekela. That sounds so good on the CS3.7

yyzsantabarbara

any journey worth taking will experience a rough patch or two. Enjoy the music!

Happy Listening!

@yyzsantabarbara, There are a multiple number of causes that might be responsible for this anomaly (including room). I’d suggest reversing components (speakers and cables) and channels from one channel to the other starting from the end (speakers) to the front of the chain.Then replacing components in the same manner. This might help you find the culprit.

@unsound Thanks for the feedback.

I was thinking that could be the case. What I did first was put my KEF LS50's back into my room and measure exactly as before. This measurement setup was done with the goal of removing the room as much as possible. The microphone was placed 3 feet directly in front of each speaker and my LEFT and RIGHT test tones were run from ROON. One tone per speaker and the analysis was done on my Windows laptop running REW

With the CS3.7 the Sound Pressure Level (SPL) graph on the REW software shows a lower level on the replaced COAX driver at 1K to 20K.

On my KEF LS50's the same test results in an almost 100% perfect match in the graph lines for each speaker. Beautiful to see that.

So the issue is not with my gear or the testing process. It is now isolated with the 2 COAX's. 

The COAX that was originally wired out-of-phase was built in 2012 (there is a date sticker). The COAX on the other speaker also has a data sticker of 2008. It also has some electronic piece that is soldered onto the uncolored terminal (non-RED). A tiny label on the piece says something about 5% adjustment. I took some photos of this and got confirmation from the previous owner that Rob Gillum told him the 2012 COAX does not need this extra soldered piece.

I was not able to reach Rob today but I have a feeling I will have to get a second 2012 driver to make the SPL identical. As I said in my prior post, the sound is really good now. There is nothing I hear that tells me there is a problem. However, I am curious about going forward with DRC so I will replace the COAX if that will fix this issue. This has to be resolved before DRC can be done (at least with the Audio Engineer I am working with).

^i’m happy that you found the source of the problem so quickly. Perhaps sending both drivers to Rob so that they can be properly calibrated and matched might be prudent.