Modern pre-pro / old school pre-amp integration

Discussion in 'Home Theater & Video' started by samwise801, Feb 12, 2018.

  1. samwise801

    samwise801 AK Subscriber Subscriber

    Messages:
    162
    Location:
    Salt Lake City, UT
    Greetings everyone! Has anyone been successful integrating an older pre-amp unit with a system also using a more...complex modern pre-pro?

    I have a Marantz AV8801 running my main system (the only “real” system in the house), and I don’t really have the room or the means for another setup. But it’s only a 2-channel system, and I also have some nice 2-channel preamps I’d like to wire up from time to time. Ya know, for the phono stages, take recording, and the like.

    Problem is, none of these older pre-amps have an HT pass-through circuit like some newer preamps do. But it seems to me there might be a way to do something similar anyway, using the many inputs on the back of my preamp, the Tape Rec outs on the preamp, and the like.

    Anyone out there also integrating an older preamp into a system with their newer, more modern HT stuff? If so, how are you doing it?
     
  2. EngineerNate

    EngineerNate AK Subscriber Subscriber

    Messages:
    886
    I'm planning on using the main pre-outs on my HT into one of the extra inputs on my vintage Denon pre to give me sound from my TV. I don't have 5.1 setup at the moment so I won't lose much.
     
  3. JoeESP9

    JoeESP9 ESL's & tubes since 83

    Messages:
    15,068
    Location:
    Philadelphia PA
    I have what is IMO a good two channel system in a dedicated treated room to which I've added HT/surround capability. No compromises were made to my two channel system. I simply added a processor, rear speakers and the necessary amplifiers. Using separates made this rather easy.

    My HT processor is connected to my two channel preamp via a tape loop. I measured the volume control position on my preamp for unity gain. All that's necessary is to set the volume control at the measured position and engage the tape monitor. From that point on everything is controlled by my HT processor. This gives me a dedicated two channel system that with a switch selection becomes an HT system.
     
  4. EngineerNate

    EngineerNate AK Subscriber Subscriber

    Messages:
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    So is your HT feeding into your pre, and you set the gain on the preamp to unity so that when it outputs to the amp the gain setting matches what's being fed to your surround speakers directly from the HT receiver?

    I'm assuming you're using the same model of amplifier for all of your channels with matched gain settings?
     
  5. JoeESP9

    JoeESP9 ESL's & tubes since 83

    Messages:
    15,068
    Location:
    Philadelphia PA
    I do not have a receiver of any type HT or otherwise. I have an HT/surround processor.

    I have very different amplification for front and rear channels. Tube and SS for the fronts and all SS for the rears. I use electronic crossovers for my bi-amplified front (Magnepan 1.7's/Dual 12" TL subs) and bi-amplified rear channels (Acoustat Model 1's/Acoustat SPW-1) to set the appropriate levels.
     
  6. EngineerNate

    EngineerNate AK Subscriber Subscriber

    Messages:
    886
    Gotcha, so you just level match manually. Cool.

    I'd like to move to a processor eventually but for now I'm stuck with a decent receiver with good pre-outs.

    Do you control HT volume on the processor? What procedure did you us to find unity gain on the preamp? My main concern with my setup is retaining volume control using the HT remote during movie/TV watching. If that goes away the WAF drops drastically.

    My current plan is to A/B some home built LR4 opamp crossovers with a DSP based crossover solution for my sub. I know that's blasphemy to the analog folks but, I was born in the digital age. :D I also want to play around with some sub T/A and bass frequency room correction to see if I can get a noticeable improvement in sound.

    Cheers
    Nathan
     
  7. samwise801

    samwise801 AK Subscriber Subscriber

    Messages:
    162
    Location:
    Salt Lake City, UT
    Sounds pretty slick. Yes, please, do tell how you measured unity gain on the preamp!

    So, your HT pre-pro is connected to your 2-channel preamp’s tape monitor input, via which output? The pre-pro’s preamp output, or something else?
     
  8. JoeESP9

    JoeESP9 ESL's & tubes since 83

    Messages:
    15,068
    Location:
    Philadelphia PA
    To measure the gain I used a signal generator (set at 1KHZ and 1v) and a DVM. Matching the input voltage with the output voltage took about 10 minutes. I then made a discrete mark on my preamp's front panel as an indicator for level setting. I could have done it by ear or just turned the volume control to halfway as the levels aren't critical. Using the Pre/pro's auto calibration feature equalizes levels and frequency balance for all the channels. Even so, when a two channel source is playing the Pre/pro and all rear channel gear can be and is turned off leaving me with a dedicated two channel system.

    My Pre/pro is an Emotiva UMC-200 which has only preamp level outputs. The front channel signals are connected to my preamp's tape 2 input. The rear channels are connected to an electronic crossover, two Adcom GFA-545's, a pair of Acoustat Model 1's and an Acoustat SPW-1. The subwoofer and center channel outputs are not used. My two channel system is bi-amped w/dual subs and I don't have the space for a center channel speaker as only panels need apply

    It would be nice to have a preamp that has a remote and an HT bypass. However, I'm quite satisfied with my ARC SP-9 MKIII.

    Most of my two channel system is listed in my sig.
     
  9. twiiii

    twiiii Super Member

    Messages:
    4,983
    Location:
    west Texas
    You could use a simple line input selector . With the two pre-amps feeding the switch box and the output feeding the amp. Now if the HT processor has Audessey or something similar and you are using it as designed; you'll need to feed the HT processor via one of its stereo analog line inputs.
     
  10. samwise801

    samwise801 AK Subscriber Subscriber

    Messages:
    162
    Location:
    Salt Lake City, UT
    Yeah, something like this?

    https://vetco.net/products/2-way-stereo-audio-rca-switch-box/vupn10317

    I’ve thought about getting an RCA switcher for a while. Anyone else out there using one? Any concerns / drawbacks / etc.?

    Seems like it would be awfully fun to use and compare the sound of two preamps side-by-side, switchable with just the push of a button. Any concern over signal loss / degradation?
     

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