And in the specific case of the ACA, what does that mean in terms of Pre amplifier?
I have a PRE that has its output configurable to a max of 2V or 4V (they call it 2x). This value is output at 93 volume value (out of a 100)... so, at the 'low' setting it will output a max of 2V with the volume set at 93, and with the 'high' setting it would output a max of 4V through the RCA connectors at the 93 volume mark. I have no idea if how is the gain affected other than the max values show... have not been able to find any reliable info, I don't know much about this specific area of Pre / Amp matching.
Would the ACA benefit from gain in the Pre amp? In the simulations I run, anything past 2V resulted in weirder output waveforms (clipping? distortion?), but that could be an error on my model. I would love some insight into what type of Pre gains / voltages would work well with the ACA?
Thanks a lot, best regards,
Rafa.
I have a PRE that has its output configurable to a max of 2V or 4V (they call it 2x). This value is output at 93 volume value (out of a 100)... so, at the 'low' setting it will output a max of 2V with the volume set at 93, and with the 'high' setting it would output a max of 4V through the RCA connectors at the 93 volume mark. I have no idea if how is the gain affected other than the max values show... have not been able to find any reliable info, I don't know much about this specific area of Pre / Amp matching.
Would the ACA benefit from gain in the Pre amp? In the simulations I run, anything past 2V resulted in weirder output waveforms (clipping? distortion?), but that could be an error on my model. I would love some insight into what type of Pre gains / voltages would work well with the ACA?
Thanks a lot, best regards,
Rafa.
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it's just post #4810 in thread ..... 
and I believe there is some post with precise data about input , output voltage and gain
however .... for latest ACA iteration .......everything is shown in this picture :
situated at Amp Camp Amp V1.5 Build Guide - diyAudio Guides
and I believe there is some post with precise data about input , output voltage and gainhowever .... for latest ACA iteration .......everything is shown in this picture :
situated at Amp Camp Amp V1.5 Build Guide - diyAudio Guides
Just to be clear, the data of the ACA is very clear, what I can't find is my PRE's gain data.
Still, for someone really expert in reading schematics and values, that may be all it takes. For someone like me, some of those numbers are hard to understand.
Just to back-up a bit, here are my simulations at 1V, 2V and 4V sine wave into a 8 Ohm 'simulated' speaker.
Do this graphs make sense? I have a full +3V ~ -3V swing when inputting 1V. When I up the input signal to 2V, then I get clipped +3.2V and (apperently unclipped) -4.8V swing. When it reaches 4V, I get less positive output than the original signal! I get a heavily clipped +2V ~ -5.4V swing.
Does this mean that if I input a 4V signal to the amp I will get heavily (insert adjective here: distorted, clipped, muddy, noisy, compressed, etc.) sound? Am I reading this wrong?
1V:
2V:
4V:
Thanks, best regards,
Rafa.
Still, for someone really expert in reading schematics and values, that may be all it takes. For someone like me, some of those numbers are hard to understand.
Just to back-up a bit, here are my simulations at 1V, 2V and 4V sine wave into a 8 Ohm 'simulated' speaker.
Do this graphs make sense? I have a full +3V ~ -3V swing when inputting 1V. When I up the input signal to 2V, then I get clipped +3.2V and (apperently unclipped) -4.8V swing. When it reaches 4V, I get less positive output than the original signal! I get a heavily clipped +2V ~ -5.4V swing.
Does this mean that if I input a 4V signal to the amp I will get heavily (insert adjective here: distorted, clipped, muddy, noisy, compressed, etc.) sound? Am I reading this wrong?
1V:
2V:
4V:
Thanks, best regards,
Rafa.
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Something is amiss with the simulation. You should be able to hit close to 8vrms into 8 ohms.
Without sweating the details I suspect you will need a preamp with a voltage gain of around '5' in order to give a decent feel to a volume control and to be able to reach full output from material recorded at lower than average levels... of which there are such examples of CD's for example.
Without sweating the details I suspect you will need a preamp with a voltage gain of around '5' in order to give a decent feel to a volume control and to be able to reach full output from material recorded at lower than average levels... of which there are such examples of CD's for example.
Attachments
Yes, your simulation looks cleaner... still, there's a couple of things there:
- C4 is missing (not sure its important)
- The 'central' array of resistors has 4 x 0.47Ohm instead of the 2 x 0.47 + 2 x 0.68
edit: Also, is the sine wave not going through the 10K R11 input? Not really sure that makes a difference, but it might?
edit2: sorry, missed the labeling there. I see its vin as expected.
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C4 has no effect in the simulation because the rail is pure and at zero AC impedance.
My mistake on the 0.68 ohm... I hadn't noticed. Changing those doesn't greatly alter things on the sim as far as I can tell.
The simulation is pretty critical on the model of FET used and I also had to tweak the bias setting resistor to obtain around 1.45 amps. I need R15 at 600 ohms to achieve that.
My mistake on the 0.68 ohm... I hadn't noticed. Changing those doesn't greatly alter things on the sim as far as I can tell.
The simulation is pretty critical on the model of FET used and I also had to tweak the bias setting resistor to obtain around 1.45 amps. I need R15 at 600 ohms to achieve that.
it's just post #4810 in thread .....
however .... for latest ACA iteration .......everything is shown in this picture :
situated at Amp Camp Amp V1.5 Build Guide - diyAudio Guides
The Amp Camp Amp Page mentions a gain of 14dB ....
I did download models for the ztx450 and the J2sk170, those may account for the differences?
For the bias, do you mean adjusting the R15 2.21K to 600? Where should I measure the bias? I was measuring the 12V on the main Q1, which, exactly like you, yields me a 0.66 on a 5K Pot (I donwloaded a linear Pot model) which mimics your 3300 - 1700 pot resistors. That gives me the 12V on Q1.
So where should I measure the current of 1.45 to ensure the correct bias? Thanks,
Rafa.
I think that that may be the correct new value for the 24V PSU (instead of the original 19V) with the voltage set to 12V on Q1 instead of 10. This changes the AMPs 5W characteristic to 8W.The Amp Camp Amp Page mentions a gain of 14dB ....
I may be completely wrong though.
The Amp Camp Amp Page mentions a gain of 14dB ....
......i think in the original article from 2012 res r12 is 68k...........
Amp Camp Amp #1
Sorry for my ignorance. If it is bias, I measure it on the PSU without any signal flowing. I get it now, I'll play a bit with the numbers. Thanks.
Thanks for the link!
Yeah, lucky you. My 'hard to drive' 4 Ohm Totem Rainmakers read 3.85V, so that would mean I would require 14.8 watts RMS, and my recently-bought supposedly 'easier to drive' 8 Ohm Kin Minis (purchased specifically for the ACA) read 2.5 ~ 3V (up to 9W RMS)... so yeah, I'm going to need the monoblocks some day.
For the time being, I would probably be listening to moderately lower levels once I manage to finish my build and find (or build?
) a Pre to drive it, as my stupid Samsung TV has no variable output on the audio-out connector, only fixed output.
I've always heard that clipping (regardless of how it sounds) is damaging to the speakers.
Does that mean that this is not entirely true? (Or not true at all?)
And how to determine how much clipping is too much, in this case of it actually sounding good?
Yes, precisely why I bought the smaller 8 Ohm Kin Minis. Lets hope I have mine built by the end of next week and I'll report back my results. Thanks!