That's what my gripe is about; it's dBu, not dBm.emrr said:Output level is quoted clearly at -10dBm, that spec is always included.
That's what my gripe is about; it's dBu, not dBm.emrr said:Output level is quoted clearly at -10dBm, that spec is always included.
emrr said:There's a 'U' (universal) version with a multi-position input pad.
What's the value of the attenuator? I don't have that documented anywhere.
Sorry for the confusion; I have mixed in my head two similar threads.emrr said:Sorry, I really have to wonder if you've even looked at his posts. It quite clearly, in pictures and documentation, has an interstage gain control.
It's not a matter of believing. The datasheet is confusing enough. And the fact that the pictures show a "-30dbm/-50dbm" switch that is not shown in either schematic does not help either.You clearly don't believe a word I've quoted from the manual for the unit he actually has. You are successfully gas-lighting the situation enough to make me look at the documentation for the dozenth time.
abbey road d enfer said:If the gain control is used to attenuate, the gain is not the specified 40 or 50dB.
So OK, we may accept it's a convoluted way of assessing the input stage's headroom.
But still, quoting levels in dBm, which implies 600 ohm loading, is in contradiction with the intended usage and what the circuit can handle.
emrr said:Ok, confusion makes sense, sorry.
'Universal Input Module' version 4BA21U1. No data available. Assume from all surrounding data and images to be a 4 position input pad switch.
I don't have any pics or data for the version with EQ, nor do I know a part #.
You're right; although the "dbm" dates from 1929, it seems only about 40 years later that some took exception to its usage for voltage.ruffrecords said:In those days dBu had yet to be invented so levels were often (incorrectly) quoted in dBm irrespective of the load impedance (Even Neve were guilty of this).
Cheers
Ian
Whoops said:Well, even if those units didn't sound any good the looks are beautiful anyway
RSRecords said:Right? If they sound garbage I'll make something out of them.
So I was looking for power supply options. I found the MNATS http://mnats.net/adjustable+phantom_power_supply.html
It has a+24v rail and a +48v rail. Would it be possible to use the +24v rail as the -25vdc I need? Has anybody tried this?
Thanks!
Whoops said:Yes you can use that, there's an LM317 regulator for that rail, the LM317 is an adjustable regulator you can adjust it to the voltage you want (between the limits of the regulator itself and the input voltage), you use the trimmer to set the voltage to 25VDC
So the actual layout does not match the schemo. My first thought was that there was an incompatibility between a +24/+48 PSU and the need for -24/+48 rails, and my fears were justified.RSRecords said:Ok cool. That's what I was thinking. My concern was with the 48vs common being the negative 25v rail.
Whoops said:Oh I'm really sorry for bringing some confusion
I missed the it was a negative 25V feed
I though you needed +25V
If you need -25V then better/easier to use a PSU pcb that is design for adjustable positive and negative rails with an LM337 for the negative rail.
You just use that rail and dont connect the the positive rail, you can check the schematic and leave the positive rail components out, we can help you on that
You can use any of the JLM audio PSUs for that,
Im sure theres also some oferings for similar psu's in the white market
emrr said:You can also buy many off the shelf supplies. The International Power modules are good in linear types.
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