2 stage Line amp/DI

[Transconductance]

I recently posted my question to another forum; however, more appropriate solutions might come from this forum. I'm in need of a rack of active DI/line-amps for my studio. The form factor and portability of the 500 series modules are well suited for my application.  Although API's 505 product might be a solution, I would benefit more from a two stage offering with a discrete topology. I can't seem to find a commercially available offering that fully complies with my requirements.  Are there any GDIY users working/developed a design or could point me towards a solution? I'm not opposed to designing and building an answer if necessary.

-TCD

 

[shabtek]

If my question mark key worked I would have hit it instead of this response:

what will '2 stages' do that 1 or 3 won't
what does discreet topology provide (and what is it)
what is the source signal
what is the destination
there are many mike pre options that have a di input
i would guess the 505 uses 2 opamps because it is a DI-EQ

 

[Transconductance]

If my question mark key worked I would have hit it instead of this response:

what will '2 stages' do that 1 or 3 won't
what does discreet topology provide (and what is it)
what is the source signal
what is the destination
there are many mike pre options that have a di input
i would guess the 505 uses 2 opamps because it is a DI-EQ

Shabetk, I apologize if my inquiry appears redundant. My interest in a two stage DI/line-amp is to control the gain of the input and output stages. Depending on the application and pedigree of the amp I sometimes like overloading these very musical discrete gain stage architectures. My desire for a discrete topology is due to not yet having found an IC based derivative that shares the character of a slightly overdriven BA183, 2520 etc..  A “Discreet” or rather discrete Op-amp is a operational amplifier comprised of transistors and passive components with differential inputs used as a voltage amplifier. The source in my application would be various analog/digital synths/DM's and or magnetic pickup instruments. The destination would be converters. I am aware that there are many mic pre with DI however from my search a lot of topologies supporting DI typically inject into the circuit down stream and simply rely on the line stage for gain. I may be missing something but why pay for the unnecessary hardware supporting the mic input stage.  Channel strips from many highly regraded old consoles support multiple gain stages post direct input. Why not an active two stage 500 series DI? I have not reviewed a schematic for the API 505 but I would assume that the 2520 is retained for the line amp as the 2510 supports the EQ..   

 

[shabtek]

I think you want a hi-z input followed by a 2520 or similar opamp with variable gain  followed by a variable attenuator
classic api offer this type of thing in 500 series--you won't need the supporting mic input circuitry and could diy a front panel as it only needs 3 holes (input, gain, attenuation).

 

[okgb]

Sounds a bit like the vp 28 , no ?

 

[Transconductance]

Sounds a bit like the vp 28 , no ?

Thank you okgb! I have sent an inquiry to CAPI about their vp 28 /ML2 products.

 

[Transconductance]

I think you want a hi-z input followed by a 2520 or similar opamp with variable gain  followed by a variable attenuator
classic api offer this type of thing in 500 series--you won't need the supporting mic input circuitry and could diy a front panel as it only needs 3 holes (input, gain, attenuation).

Shabtek, thanks for pointing me towards the CAPI products. I would like to review a schematic for the circuit to identify where the DI injects into the circuit; however, the CAPI modules look promising. I don't believe that I would need to redesign a front panel to accommodate for my application if I could insert into my patch bay (patched to my lunch boxes). Until I review a schematic I'm uncertain how the channel is configured; however, from what I can tell the VP28 features a mic/line switch on the front panel that would accommodate the XLR input for the module.