Sounds good, better than I expected. They need to break in for a while.
The speakers are DIY, altec 515 in my the base horn and a TAD2001 on top with a Charles Hanson designed quadratic throat wave guide.
The speakers are DIY, altec 515 in my the base horn and a TAD2001 on top with a Charles Hanson designed quadratic throat wave guide.
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Thanks for the accolades
I did some testing today. What I found is that I could increase-decrease the THD by varying the Vds of the THF-51. I started at 35 volts and had about .59% THD by increasing the Vds to 37 I could get it down to .44%. I could go even lower but then you are cutting the voltage across the ccs. The nice thing is I could set the distortion of each mono block to the same distortion.
So you will see that they look very similar but one is at 37v the other is at 37.44v.
They sound great big and open. They do sound “loud” as you push them and the distortion goes up. Luckily with 100dB speakers I don’t need much.
I did some testing today. What I found is that I could increase-decrease the THD by varying the Vds of the THF-51. I started at 35 volts and had about .59% THD by increasing the Vds to 37 I could get it down to .44%. I could go even lower but then you are cutting the voltage across the ccs. The nice thing is I could set the distortion of each mono block to the same distortion.
So you will see that they look very similar but one is at 37v the other is at 37.44v.
They sound great big and open. They do sound “loud” as you push them and the distortion goes up. Luckily with 100dB speakers I don’t need much.
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A few more pictures for Zen Mod.
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I have done some further investigations. I see that the gain of the amp changes quite a bit with the load impedance. I confirmed this on the bench with different loads.
Some of the “loud” I was hearing was from impedance variations in my horn speakers. The 515 is 16ohms and the horn is set at 10ohm shunt before the autoformer.
I placed a 15ohm 10w in parallel with the speaker and the sound stabilized.
The amps are sounding great with this change and time to break them in.
Some of the “loud” I was hearing was from impedance variations in my horn speakers. The 515 is 16ohms and the horn is set at 10ohm shunt before the autoformer.
I placed a 15ohm 10w in parallel with the speaker and the sound stabilized.
The amps are sounding great with this change and time to break them in.
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