Sex with open baffles

[AJWard549]

Get your minds out of the gutter! Recently completed an open baffle project with Lii Audio 6.5 in full range drivers and using with the sex 3.0. Holy shit I can’t believe how good my lps sound! Using my main system preamp (restored McIntosh C24) and I just want to sit in front of these speakers all day! Thanks Doc and team for making this kit possible, I am amazed by the sound I am hearing.

[AJWard549]

Adding a photo helps bring the whole story together!

I am curious, I am pleased that listening through the open baffles the amp is silent. No hum. This is the case whether I am using the setup described here or if I have a source like an external DAC connected directly to the amp. But if I listen with headphones, I do hear a hum in between tracks. Headphones are Grado SR325 (original if that makes a difference). Just a phenomenon with headphones? I checked, and the ground and terminal at #36 are not touching.

[Paul Birkeland]

With Grado headphones and IEMs some find it helpful to mod the amp to pad down the output a bit.  Did you wire for 4 ohms when building the amp?  That will also help a bit.

[AJWard549]

Thanks Paul, I did originally have the amp wired at 4 ohm and the hum was present, now at 8 ohm it doesn’t sound much different if at all via headphones. I do have attenuation between my source and amp as well.

[Paul Birkeland]

There's some info here:
https://forum.bottlehead.com/index.php?topic=13832.0

The first thing to try though is to connect the inner and outer bottom headphone jack lugs to see if/how much that helps.

[AJWard549]

Paul

Thank you for your suggestion, unfortunately connecting the bottom lugs of the headphone jack made no discernible difference. Since the low level hum only is audible when listening with headphones, and since it is only audible  between music tracks I don't think I will try any of the other options listed in the attached link. I really REALLY love the sound of the SEX3 with the open baffle speakers and wouldn't want to compromise that sound since the SEX3 will soon be primarily used to drive the speakers rather than headphones!

I do have the C4 upgrade that I have yet to install. Do you think this would make a difference? I am guessing no, but if so I could proceed with the upgrade. Otherwise I want to live with the stock sound for a while longer. I am pretty happy with it!

Andrew

[Paul Birkeland]

I really REALLY love the sound of the SEX3 with the open baffle speakers and wouldn't want to compromise that sound since the SEX3 will soon be primarily used to drive the speakers rather than headphones!

In reply #5 to the thread I linked to, you can put 32 ohm resistors in place of the 8 ohm ones I've drawn in and just not bother with the other pair of resistors on that diagram. Provided you move the wires as indicated in that picture, speaker performance will not be altered, but you will lose the switching function of the jack that automatically turns the speakers off when you plug in headphones.

[Karl5150]

This quote from a review of Tekton OB45s sums it up for me pretty well:
"Be careful not to fall in love with the full-range idea for yourself. The
     best of them are so good that they may move upwards the tolerance
     threshold of future reviews of conventional products...or even spoil it."
Although technically a hybrid, they were my gateway to the OB sound. Enjoy.
Karl

[AJWard549]

Nice Karl!

I see you are rocking some OB yourself connected to the Stereomour... I am thinking that might be my next build but not sure. I have to be honest, I have been working in my office this evening after supper and listening to the Lii Audio 6.5 (Fast 6) full rangers in the open baffles I have in the photo in post 1 and am still just blown away with the sound. I am listening to acoustic guitar/singer songwriter tonight and I feel like I am sitting in a venue while I work! While not on par with my analog front end in the main room, the SeX3 with the OB's and a Border Patrol DAC with a dedicated Mac mini as a music server is really putting a big smile on my face while I grade assignments!