What’s On the Bench Tonight (OBT)

[adason]

Yup, best to simulate it with soldering iron
(to cite Wayne)

 

[xrk971]

I finalized the crossover for the Signature 80’s today. Took a new set of raw data and tweaked the crossover - several components changed values oh so slightly but they make a difference.

Here is the new measured (yellow) vs predicted (blue) response:

Here is the revised crossover with P2P:

Speakers completed and now in stereo:

Video of speaker in stereo:

 

[xrk971]

Here’s the video:
First Sound of LSA Signature 80 in Stereo - YouTube

 

[Dibya]

Hi X,

which amp are you using for test ? sounds like class D

 

[xrk971]

You have golden ears! Here is the chain. Warp-1 is TPA3255 amp with BTSB panel mount input buffer.

Amazon HD music (track was only 48kHz 24bit)//USB//Khadas TB1 (192kHz 24bit setting)ES9038 DAC//SMSL E30 preamp/headphone amp//Warp-1 amp with RCA inputs//12 ga speaker cables//LSA Signature 80 speakers.

 

[xrk971]

This 6.5in Al cone woofer sample I have just happens to fit where the Purifi used to go. This ribbon tweeter also happens to fit where the RAAL used to go. Hmm… could the TL work? It would just be too much luck if it did.

 

[dBel84]

serendipity

 

[BasicHIFI1]

Here’s the video:
First Sound of LSA Signature 80 in Stereo - YouTube

Your next video is amazing:

Test of SuSyLu 100W Class A Amp

the vocals at 6:25 sound like a live performance even over my PC and headphones. Huge clarity.

 

[xrk971]

Thank you, BasicHifi. That video does sound great - the amp is one of the best I have made (100w of class A) and the speaker is my main reference FAST TL.

I should try listening to the LSA 80’s on Class A next.

 

[BasicHIFI1]

I think you are the best person to ask: how does listening to the You Tube over a mobile phone and supplied headphones compare to the real thing? Is it 50%, 80% of the same sound, roughly?

 

[xrk971]

It sort of depends on how good your headphones are and how good your DAC and headphone amp are as well. I tested it myself with OB-1 headphones ($55) and basic headphone output from Behringer UM2 audio interface on my PC. It is about 75% as good - which is really surprising given that it was recorded with an iPhone 12 Pro max.

 

[xrk971]

I finished assembling four new crossovers for the TLs for a customer in Hawaii and a friend in Texas. As I was testing them, I discovered what is meant by inductor crosstalk. Air coil to air coil transformer!

Demonstration of Inductor Crosstalk in a Crossover - YouTube

 

[Dibya]

I think it is happening due to mutual inductance of the inductor

 

[adason]

All it takes is to change the orientation of one of those coils.

 

[adason]

Try #6

 

[adason]

You need to put at least 1A through to get some power.
I am tempted to try this next. Credit goes to Juma.

I have 'simulated' this circuit. Works. Had some hum on linear supply, so i switched to 12v brick. No hum. Sounds loud and clear.

 

[adason]

I started with 8 ohm for those resistors, as i do not like things toasty.
Definitely nice circuit. Even i do not fully understand the nature of the feedback.
Vunce, try this circuit.

 

[von Ah]

Fascinating! Amazingly simple circuit.

 

[Vunce]

I was hoping for a roadmap, sweet!!
I have a couple of Meanwell bricks, I’ll use a capMx to drop some voltage for this amp.
Thanks Adason

 

[adason]

When i used linear supply and variac, optimum power supply was about 12-14 volts only. Increasing it to 20 decreased the volume and was not sounding as good as at 12v. Just my observation. Maybe with some modification, it could work on higher supply. But why, it sounds plenty loud now.