I was able to measure an unclipped 100V peak-to-peak signal at my tube mixer output (measured directly at the XLR/transformer secondary). 33 dBu. Not bad...
Impressive audio level
- Thread starter Holger
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I never found much need for more signal swing beyond 20dB above nominal 0VU.
I don't recall the exact output level for Peavey's old (AMR) tube mic preamp but the Peavey service department asked me to design a passive pad so customers could patch the Peavey preamp into their Mackie 8-bus mixers without overloading the mixer input.
I guess you can always pad this down to feed an A/D converter.
JR
I don't recall the exact output level for Peavey's old (AMR) tube mic preamp but the Peavey service department asked me to design a passive pad so customers could patch the Peavey preamp into their Mackie 8-bus mixers without overloading the mixer input.
I guess you can always pad this down to feed an A/D converter.
JR
ruffrecords
Well-known member
JohnRoberts said:
This is what it is capable of, not what it normally outputs. It just means it has a lot of headroom above a nominal +4dBu.
Cheers
Ian
In the USA we'd say your tube mixer has some Balls Holger 8)
pucho812
Well-known member
what tube mixer is it?
I'm not a tube guy but back when I was designing (solid state) mixers there was a constant tension between headroom and signal to noise... If there is 100Vp-p output what is the noise floor below that? Or more importantly where is the noise floor below nominal 0VU.ruffrecords said:
Peak output signals near 40dB above 1V may be ignoring some S/N or noise floor benefit from scaling nominal 0VU up to a hotter voltage.
Enjoy and do whatever floats your boat... design decisions often involve tradeoffs. I never owned or designed a piece of gear that could accept that much signal on a line input ***
JR
*** Note some old Peavey power amps (that I didn't own or design) would bring a single ended signal direct into the top of the input potentiometer attenuator. Those amps could take your 100V signal and harmlessly pad it down. They could routinely take speaker level voltages as inputs.
12afael said:
What does headroom sound like? Clean?
I don't read too many post about the pursuit of linearity.
JR
PS: Sorry I do not mean to appear negative about a 100V mixer output, just exploring any unintended consequences. You may want to add a shock hazard warning to then line output. 8)
12afael said:
Human perception correlates distortion with louder.
For musical instruments (like a flute) louder sounds contain more overtones (distortion).
The human voice gets more complex (distorted) the louder we sing.
I once experienced a clean powered speaker playing very loudly in a small space (a sound booth at a trade show). Because it was so clean we didn't realize how loud it was until we tried to speak and could barely hear ourselves let alone each other.
So I'm afraid more headroom may play louder but being clean does not sound as loud as a path that saturates.
JR
PS I apologize for this veer and congrats on making 100Vp-p
okgb
Well-known member
I thought it was something for installing windows or doors
It doesn't automatically assure you of good gain staging
It doesn't automatically assure you of good gain staging
ruffrecords
Well-known member
pucho812 said:
It is the 12 channel, one metre long, EZTubeMixer that Holger built.
Cheers
ian
ruffrecords
Well-known member
JohnRoberts said:
Depends on the gain but it can be below -80dBu.
Cheers
Ian
>> 100V peak-to-peak signal
> I never owned or designed a piece of gear that could accept that much signal on a line input
> You may want to add a shock hazard warning to the line output.
100V p-p is "only" 35V RMS. Under many codes, this needs no protection or warning.
If a 3dB pad is added (once SOP to ensure known impedance interface), it just squeaks under 25Vrms which is practically harmless under most codes.
I just designed a line-input to take 12V clean but 50V without damage (just in case it ends up in Holgar's hands <G> ). Actually if built with two 1/2W resistors it can eat 150Vrms without damage. Nominal input ~~200mV (-12dBu), input hiss level near 5uV (-103dBu), 90dB S/N. (I'm not sure the following stage is so low-hiss; not my job.) Not an elaborate plan.
> I never owned or designed a piece of gear that could accept that much signal on a line input
> You may want to add a shock hazard warning to the line output.
100V p-p is "only" 35V RMS. Under many codes, this needs no protection or warning.
If a 3dB pad is added (once SOP to ensure known impedance interface), it just squeaks under 25Vrms which is practically harmless under most codes.
I just designed a line-input to take 12V clean but 50V without damage (just in case it ends up in Holgar's hands <G> ). Actually if built with two 1/2W resistors it can eat 150Vrms without damage. Nominal input ~~200mV (-12dBu), input hiss level near 5uV (-103dBu), 90dB S/N. (I'm not sure the following stage is so low-hiss; not my job.) Not an elaborate plan.
Since 100Vp-p is roughly +33dBu that makes a respectable 113 dB dynamic range (18+ bits). A pad on the output down to more conventional operating signal level would reduce the signal and the noise so that dynamic range is preserved. (of course that ASSumes the -80dBu and +33dBu exist at the same time.).ruffrecords said:
JR
PS: I was kidding about the voltage warming label but you don't get that kind of signal swing from a 9V battery supply.
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