Topic: Analog In mod UA-5s

[shaggy]

Quicky question I just wanna confirm if you use the RCA analog ins on the mod UA-5s from Oade if they will reap the benefits of the flavor mods?  More specifically, the question is (since I do not know any better) do the op-amps on the mod affect only the mic-in or the whole analog-in section?

[Chanher]

I believe the "+" affects the RCA input, as well as lowering noise floor. Just a regular mod (without the "+") affects the mic input.

[shaggy]

Channer:  thanks +T, I should have said that I meant the plus (+) mods.  I know that the RCA inputs are made better with a lower noise floor but I was more wondering if the op-amps are moded, then does all the analog inputs have access to it?

[Chanher]

Well the rca inputs have their own gain control, as do the mic inputs. I know VERY little about audio circuitry, but I would guess that you can't have two seperate gain controls for one analog gain stage. It would seem logical that they each have their own gain stage. Once again, I don't know squat about this kinda stuff.

ps, I know that on top of the ua-5 there is a simple schematic of the ua-5. Perhaps our answer is there (I'm too lazy).

[poorlyconditioned]

Well the rca inputs have their own gain control, as do the mic inputs. I know VERY little about audio circuitry, but I would guess that you can't have two seperate gain controls for one analog gain stage. It would seem logical that they each have their own gain stage. Once again, I don't know squat about this kinda stuff.

ps, I know that on top of the ua-5 there is a simple schematic of the ua-5. Perhaps our answer is there (I'm too lazy).

I've traced the UA5 .

I don't know about the Oade mods, but I have upgraded the RCA ins on my unit.

Here is the rough gain structure:

Line In L ----***----amp3a------
                                           \
L (hot +)  - amp1a\               \
L (gnd) ----------&&&   - amp2a ----- amp2b ---- ADCL (unbalanced)
L (cold -)  - amp1b/

Dual opamps, eg., 1a and 1b are on same chip.
Right side uses two new chips (four opamps) and shares amp3b .

***: gain on *input* of audio (simple attenuator)
&&&: gain on mic input is via "instrumentation amplifer" involving amp1a,1b and 2a.  That is, there is real gain variation, not just attenuator.

Poorlymodded version: AD712 for amp1a,1b.  AD8620 for others.  Should improve AD712 though.

  Richard

[Chanher]

thanks Rich

[shaggy]

I've traced the UA5 .

I don't know about the Oade mods, but I have upgraded the RCA ins on my unit.

Here is the rough gain structure:

Line In L ----***----amp3a------
                                           \
L (hot +)  - amp1a\               \
L (gnd) ----------&&&   - amp2a ----- amp2b ---- ADCL (unbalanced)
L (cold -)  - amp1b/

Dual opamps, eg., 1a and 1b are on same chip.
Right side uses two new chips (four opamps) and shares amp3b .

***: gain on *input* of audio (simple attenuator)
&&&: gain on mic input is via "instrumentation amplifer" involving amp1a,1b and 2a.  That is, there is real gain variation, not just attenuator.

Poorlymodded version: AD712 for amp1a,1b.  AD8620 for others.  Should improve AD712 though.

  Richard

+T Richard,

If you had to take a guess from Doug's pitch on the website (when he was selling these units), do you think he replaced amp2b with the op-amp that gave the final flavor of the mod (ie: W, P or T mods)?

This is what he had said:

"Discrete left & right inputs for either stereo input devices or 2 separate audio channels. Delivers clean digital audio conversion at resolution up to 24-bit/96 kHz. Modified to allow the digital coax and optical outputs for stand alone operation without a computer. It can also be used with a computer to output data simultaneously to both coax and optical digital connectors, in addition to your computer! A full analog input rebuild in included with this MOD. This replaces the input capacitors, which are SMD electrolytic (higher distortion and noise) with SMD film caps (lower distortion and noise) as well as the input and ADC buffer Op Amps. We use very high grade, very low noise Op Amps for this, chosen by ear for a warmer sound, with better depth and high frequency character. Tube like in character with a huge soundstage that satisfies the tube lover!

The PLUS MOD further reduces noise and distortions in the UA5 by improving the DC supplies, phantom power and RCA inputs."

Trying to work another ADC option for the Lemosax (as I have no bodies for my Schoeps caps and usually run it inot a modSBM) to my T+mod.  I always thought the RCAs would be improved with the flavor of the mod, as I thought a complete analog upgrade would include the RCAs.  But from your trace diagram, it seems like there are alot more op-amps in the box than I had originally thought.

[poorlyconditioned]

I've traced the UA5 .

I don't know about the Oade mods, but I have upgraded the RCA ins on my unit.

Here is the rough gain structure:

Line In L ----***----amp3a------
                                           \
L (hot +)  - amp1a\               \
L (gnd) ----------&&&   - amp2a ----- amp2b ---- ADCL (unbalanced)
L (cold -)  - amp1b/

Dual opamps, eg., 1a and 1b are on same chip.
Right side uses two new chips (four opamps) and shares amp3b .

***: gain on *input* of audio (simple attenuator)
&&&: gain on mic input is via "instrumentation amplifer" involving amp1a,1b and 2a.  That is, there is real gain variation, not just attenuator.

Poorlymodded version: AD712 for amp1a,1b.  AD8620 for others.  Should improve AD712 though.

  Richard

+T Richard,

If you had to take a guess from Doug's pitch on the website (when he was selling these units), do you think he replaced amp2b with the op-amp that gave the final flavor of the mod (ie: W, P or T mods)?

This is what he had said:

"Discrete left & right inputs for either stereo input devices or 2 separate audio channels. Delivers clean digital audio conversion at resolution up to 24-bit/96 kHz. Modified to allow the digital coax and optical outputs for stand alone operation without a computer. It can also be used with a computer to output data simultaneously to both coax and optical digital connectors, in addition to your computer! A full analog input rebuild in included with this MOD. This replaces the input capacitors, which are SMD electrolytic (higher distortion and noise) with SMD film caps (lower distortion and noise) as well as the input and ADC buffer Op Amps. We use very high grade, very low noise Op Amps for this, chosen by ear for a warmer sound, with better depth and high frequency character. Tube like in character with a huge soundstage that satisfies the tube lover!

The PLUS MOD further reduces noise and distortions in the UA5 by improving the DC supplies, phantom power and RCA inputs."

Trying to work another ADC option for the Lemosax (as I have no bodies for my Schoeps caps and usually run it inot a modSBM) to my T+mod.  I always thought the RCAs would be improved with the flavor of the mod, as I thought a complete analog upgrade would include the RCAs.  But from your trace diagram, it seems like there are alot more op-amps in the box than I had originally thought.

I don't know...

  Richard

[Busman Audio]

There is an op amp for the RCA inputs and that can be changed to match the flavor of the mod. I do this on my mods and also change out the caps on the inputs there to help with the sound. Of course it doesn't quite sound as good as running into the XLRs because it is a totally different circuit and not a pre amp on the RCAs.

So yes you can flavor the RCAs and I would reccomend it with the crappy op amp that is used in that path.