Hi Tonza,
Alumina ceramic is best, see this post,
for grease I use some generic stuff, not electric conducting.
Yep, the bass is passive, two 10" Alcones matches with the Accuton mid for sensitivity.
Alumina ceramic is best, see this post,
for grease I use some generic stuff, not electric conducting.
Yep, the bass is passive, two 10" Alcones matches with the Accuton mid for sensitivity.
I went with the initial bill of material recommendations for 1.95 A bias - 0.33R for R131, 2 x 0.33R for R132.
Strange,
the schematics on page 1 show all 0.12 for R132
BOM needs to be adjusted ?
Grts,
Danny
Trying to sneak in some late night listening (actually early morning) - can't crack up the volume too much. My speakers are Carreras by Paul Carmody. Using the Salas DCG3 preamp, Subbu V3 DAC.
Carrera - undefinition
Sensitivity: 83-84 dB ? Theoretical I suppose.
Min impedance: about 5.2 ohms.
Sorry, you say:
Music with low/very low DR?The Carrera sensitivity is 81-82 dB, so not ideal for a 20 watt amplifier, but I am not finding the ALPHA 20W lacking at moderate volumes in any way.
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Glad it is all working and singing well for you Zman. Enjoy!
I certainly just listen to my Alpha BB lately now maybe 5 hrs a day - conveniently as I sit at my computer working on writing, the amp is playing my favorites on a playlist. It’s hard to leave the speakers and amp when I have to finally power down at 2am for the next day.
I certainly just listen to my Alpha BB lately now maybe 5 hrs a day - conveniently as I sit at my computer working on writing, the amp is playing my favorites on a playlist. It’s hard to leave the speakers and amp when I have to finally power down at 2am for the next day.
Good question, Vunce. I would think it would be useful for complex, difficult speakers, say three ways with third orders or more. For two ways with 1-3 orders, maybe no. But if you have the impedance curves for the speaker and it goes below say 6 ohms, YES, I would do it.
Hugh
Hugh
Hugh,
I found an old HiFi Classic review that had impedance curve specs for my Forte speakers and I’m very surprised with huge variation in impedance(even though they are labeled 8ohm):
“The system's minimum impedance was 4 ohms at 150 Hz, which was also the frequency of its maximum output. The impedance rose to a peak of 20 ohms at 65 Hz, then dropped back to 5 ohms at 42 Hz, rising again to about 19 ohms at 20 Hz. It reached an unusually high 130 ohms at 2,200 Hz, then descended to the range of 8 to 12 ohms between 6,000 and 20,000 Hz.”
So, given that the impedance drops below 6ohms for frequency’s that require the most power, I think I will increase my ALPHA20 bias. Thanks.
Cheers,
Vunce
I found an old HiFi Classic review that had impedance curve specs for my Forte speakers and I’m very surprised with huge variation in impedance(even though they are labeled 8ohm):
“The system's minimum impedance was 4 ohms at 150 Hz, which was also the frequency of its maximum output. The impedance rose to a peak of 20 ohms at 65 Hz, then dropped back to 5 ohms at 42 Hz, rising again to about 19 ohms at 20 Hz. It reached an unusually high 130 ohms at 2,200 Hz, then descended to the range of 8 to 12 ohms between 6,000 and 20,000 Hz.”
So, given that the impedance drops below 6ohms for frequency’s that require the most power, I think I will increase my ALPHA20 bias. Thanks.
Cheers,
Vunce
Danny, no requirement to change R132, 0.12R is unchanged.
Hi Hugh,
It was because Zman used 0.165r (2x0.33) for sensor with 0.33r emitter.
I proposed to use 0.11r (3x0.33) or 0.12 for sensor.
Grts,
Danny
Hi Vunce,
The Alpha20 1.95A can drive about 1-1.5 lower lower ohm compared to 1.45A.
It also depends how much voltage/power you need,
lucky for you your speakers are high sensitivity.
Grts,
Danny
F..k had to goto doctor , took the tests . Fever/flu 38.5C feeling a lot weaker. 3 days of work
Danny can you simulate the amp with a loudspeaker as load ? there the png
I think i goto bed.
Attachments
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Hugh,
I found an old HiFi Classic review that had impedance curve specs for my Forte speakers and I’m very surprised with huge variation in impedance(even though they are labeled 8ohm):
“The system's minimum impedance was 4 ohms at 150 Hz, which was also the frequency of its maximum output. The impedance rose to a peak of 20 ohms at 65 Hz, then dropped back to 5 ohms at 42 Hz, rising again to about 19 ohms at 20 Hz. It reached an unusually high 130 ohms at 2,200 Hz, then descended to the range of 8 to 12 ohms between 6,000 and 20,000 Hz.”
So, given that the impedance drops below 6ohms for frequency’s that require the most power, I think I will increase my ALPHA20 bias. Thanks.
Cheers,
Vunce
Most of that sounds pretty reasonable, it’s the 5ohms at 42Hz that’s a bit problematic, but there is not much content there except for open G on a bass. A lot of the sins of a crossover are absolved with 99dB sensitivity. Basically it doesn’t require much current at all. With higher bias you should hear improved bass authority when listening to bass guitar or more HT type stuff. Most music bass with kick drums is at 55Hz low. The 110ohms at 2kHz means the speaker is acting alimony like a liar of headphones impedance wise. The only cure here is higher voltage, but Alpha 20 can swing +/-15v easily so that will sound good unless you are playing very loud.
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Most of that sounds pretty reasonable, it’s the 5ohms at 42Hz that’s a bit problematic, but there is not much content there except for open G on a bass. A lot of the sins of a crossover are absolved with 99dB sensitivity.
Thanks for the input X.
Danny,
Since the cpu coolers work so well, I will change the appropriate resistors to increase bias to 1.46A and give a listen.
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If you have the .asc file I can plug it in, otherwise you can find my ltspice files a few pages back.Danny can you simulate the amp with a loudspeaker as load ?
Grts,
Danny
Let's see if I feel a bit better tomorrow or the day after.If you have the .asc file I can plug it in, otherwise you can find my ltspice files a few pages back.
Grts,
Danny
Flu, fever
Regards. Toni
HughZman,
Would you like to give the interested throng here your thoughts about the sound of your ALPHA?
Has all the angst during fault finding been worth it now it is making music?
HD
Have you seen post 2160?
Fab
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