Good advice. Most DMMs are capable of measuring 48-440 Hz with a reasonable level of accuracy. Check the manual for your meter if you aren't sure. I generally recommend using 400 Hz. You can generate a test tone using WavTones and play it on repeat on your media player. Then follow Andrew's methodology above to determine the attenuation at the given setting of the volume control.
Tom
Thanks guys. I was already getting some test tones tonight. I've been thinking to get the 1khz 0dBFS to play on the DAC and measure the output with my cheap oscilloscope and see at which attenuator position it puts out 2V. I will probably get to that tomorrow and report on the outcome.
The DAC has a rotary encoder and I seem to remember that the control is somewhere done on the oversampling part (300 something kHZ) before downsampling again.
The DAC has a rotary encoder and I seem to remember that the control is somewhere done on the oversampling part (300 something kHZ) before downsampling again.
So I ran several 0dBFS wav sound ranging from 400 to 2000Hz sine into my DAC and measured the voltage between pin 2 and 3 of the XLR output with my cheap battery driven oscilloscope. Turns out (considering all the inaccuracies) that when setting the attenuator to 74% (so it's not linear) the DAC put out a peak-to-peak voltage of 1.930V. I thought this close close enough to the specified 2V input sensitivity of the Mod286. I then switched on the Mod286, connected my big speaker and played some music. With only one speaker running, because I have attached only one board to a heat sink yet, I measured SPL on average of 80dB and peaks of 90dB. Loud enough for me 
and yes I can confirm some of the other reports... the Mod286 is dead quite with no input signal present.
Am I correct in my thinking that the 0dBS tone is the loudest the DAC will put out and setting the attenuator to ca 2V peak to peak output the Mod286 will not be driven into clipping even at the loudest peak in real music? Please correct me if I am wrong.
Thx.
and yes I can confirm some of the other reports... the Mod286 is dead quite with no input signal present. Am I correct in my thinking that the 0dBS tone is the loudest the DAC will put out and setting the attenuator to ca 2V peak to peak output the Mod286 will not be driven into clipping even at the loudest peak in real music? Please correct me if I am wrong.
Thx.
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On a slightly different topic, which puzzled me during today's test. When cranking up the DAC to 100% (Mod286 was switched off) I measured a peak-to-peak value of ca. 8.5V. How does this correspond to the species 4Vrms of the DAC XLR. I thought the formula is Vrms = 0.3535 x Vpeaktopeak?
Where am I going wrong?
Thx.
Where am I going wrong?
Thx.
There's no one size fits all when it comes to RMS. You can see the full explanation here: Root mean square - Wikipedia
The ratio between the peak and RMS value of a sine wave is 1/sqrt(2) = 0.707
As Vpp is 2*Vp, the ratio between the peak-to-peak and RMS voltage would be half that so 0.354 as you point out.
Tom
The ratio between the peak and RMS value of a sine wave is 1/sqrt(2) = 0.707
As Vpp is 2*Vp, the ratio between the peak-to-peak and RMS voltage would be half that so 0.354 as you point out.
Tom
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Does your voltmeter give peak to peak voltages?
Normally we only see and estimate peak to peak on an oscilloscope screen. Some will display a reading.
Most voltmeters measure the average over a short time period (roughly 400ms for the cheap hand helds) and convert that average to a Vac reading using a scaling factor that assumes the waveform is a sinewave.
You can work back from that Vac reading to a Vpeak (Vpk) by multiplying by sqrt(2) when you know the signal was a single frequency sinewave.
Then Vpp (peak to peak) is double the Vpk.
I measured the Vpp with my (cheap) handheld oscilloscope not with my multimeter. Yes the calibration might not be entirely accurate, but it gets me in the ballpark I guess.
I am about to order the components for the two Power-86 boards, which go into my two Mod286 monoblocks. Before I do, could some please confirm the capacitor choice for this particular setup.
I have read
Modulus-86 build thread
Does this recommendation, that is 2 x 22.000uF / 50V per Power-86, still holds for my setup? Our should I change anything? As Tom put it, the capacitors costs are small compared to the overall costs, so why skimp.
I have read
Modulus-86 build thread
Does this recommendation, that is 2 x 22.000uF / 50V per Power-86, still holds for my setup? Our should I change anything? As Tom put it, the capacitors costs are small compared to the overall costs, so why skimp.
Sorry I am too much of a beginner in order to help. Do you have a solution already? Please post it here in case others run into similiar trouble.
Thx
SH
What do you mean by "hv+"? +28 V? +35 V? That's not supposed to be anywhere near the 8-pin SOICs.
I'll be more than happy to. However, while I do check DIY Audio frequently, I check my email a lot more frequently. Also a short "help me" post tends to drown in other chatter. By far the most effective way to get my attention is to send me an email, which you can do through the Contact Us form on my website or by taking my user name here and adding @neurochrome.com to it.
Tom
While I am waiting for the chasis to arrive from Modushopbiz, I have put together the overall costs for my two Mod286 Monoblocks.
Cost per Monoblock Mod286: approx. 660 EUR / approx. 725 USD
Costs for two Monoblocks Mod286: approx. 1.320 EUR / 1.452 USD
Please find attached the PDF overview for details.
One can probably shave off 100-200 EUR per Monoblock by saving on the housings, the IEC inlets, the speaker posts (I am using 4 instead of 2 to keep the bi-wiring/amping option open) and probably the trafos...
Of course it is interesting to compare the specs (data) & costs of the two Mod286 with commercially available monoblocks or amps. I picked three at random from one of the many best-of-lists and compared the Mod286 with NAD M22, Accuphase A-70 and Audiolab 8200MB. Of course this is just a quick check and not representative. Quick summary: price ca. 2-4 times as high at mostly lower or at best comparable specs such as THD+N etc. - so I guess the Mod286 is a very good deal. I am of course excited to finish it and see if the listening experience equals the very good specs.
Cost per Monoblock Mod286: approx. 660 EUR / approx. 725 USD
Costs for two Monoblocks Mod286: approx. 1.320 EUR / 1.452 USD
Please find attached the PDF overview for details.
One can probably shave off 100-200 EUR per Monoblock by saving on the housings, the IEC inlets, the speaker posts (I am using 4 instead of 2 to keep the bi-wiring/amping option open) and probably the trafos...
Of course it is interesting to compare the specs (data) & costs of the two Mod286 with commercially available monoblocks or amps. I picked three at random from one of the many best-of-lists and compared the Mod286 with NAD M22, Accuphase A-70 and Audiolab 8200MB. Of course this is just a quick check and not representative. Quick summary: price ca. 2-4 times as high at mostly lower or at best comparable specs such as THD+N etc. - so I guess the Mod286 is a very good deal. I am of course excited to finish it and see if the listening experience equals the very good specs.
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