Products > Test Equipment

To all the audio guys out there.

<< < (4/7) > >>

Messtechniker:
M-Audio Delta AP 192 and Audio Tester software.
And Siglent 2042X

David Hess:

--- Quote from: pope on November 12, 2024, 10:15:32 pm ---The QA403 will output "only" around 20dBu which won't cut it for such measurments.
--- End quote ---

20 dBu is 22 volts peak-to-peak. so the QA403 is probably relying on integrated operational amplifiers with a 30 volt supply.  This matters because it means an external amplifier will have to use a higher voltage design making it non-trivial.


--- Quote ---Has anyone run into a similar situation and if so, how did you resolved it?
--- End quote ---

I have, and I immediately designed and built a small amplifier.

Unfortunately high voltage operational amplifiers are not usually suitable for low distortion audio, so some kind of hybrid design will probably be required.

Someone:

--- Quote from: David Hess on November 14, 2024, 01:58:09 am ---
--- Quote from: pope on November 12, 2024, 10:15:32 pm ---The QA403 will output "only" around 20dBu which won't cut it for such measurments.
--- End quote ---
20 dBu is 22 volts peak-to-peak. so the QA403 is probably relying on integrated operational amplifiers with a 30 volt supply.  This matters because it means an external amplifier will have to use a higher voltage design making it non-trivial.
--- End quote ---
30dBu/25Vrms/70Vp-p is achievable for a differential signal (as pro audio tends to) on 36V rails so those levels aren't out of this world or impossible to find in commercial products. However pro audio does get off into crazy prices for what it is.

AVGresponding:

Zero999:

--- Quote from: Messtechniker on November 12, 2024, 10:41:25 pm ---
--- Quote from: pope on November 12, 2024, 10:15:32 pm ---
Has anyone run into a similar situation and if so, how did you resolved it?

--- End quote ---
By making this:


and this

(Attachment Link)

--- End quote ---
It appears as though you either forgot to upload the second attachment, or the forum lost it.

Regarding the first attachement. To change it from 125V to 48V, R4 and R10 need to be decreased from 47k to 18k, otherwise T1 and T6 will be off.

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