Equalizer connection question

Discussion in 'General Audio Discussion' started by bradmcl, Nov 6, 2008.

  1. bradmcl

    bradmcl New Member

    This is slightly embarassing to admit. I need help with something pretty basic.
    I bought a cool old graphic equalizer but I am confused as to how to connect it to my stereo system.
    I connected it between my CD output and my receiver input, and it worked great for CDs, but then it wasn't able to do anything for FM, Phono, or Tape.
    I have a Sansui 9090db receiver with a back panel power/preamp jumper. Should I removed the jumper and connect the equalizer between the power amp and the preamp? I haven't tried this yet. I don't want to wreck my Sansui. Maybe there is nothing to fear, but ???
    If I want to connect this equalizer to a standard receiver that doesn't offer an option to separate the power amp and preamp sections, is there a solution for this dilemma or am I stuck changing the equalizer connection every time I want to switch between CD/Phono/FM/Tape?
  2. Hook it thru the tape loop of your receiver then hook your tape deck to the EQ's own TAPE IN and OUT.
  3. Jon_Logan

    Jon_Logan Addicted Member

    Left Coast
    Lower noise floor if connected in the Tape loop.
  4. Franksta

    Franksta AK Subscriber Subscriber

    Yes you can connect it into the preamp out main in jacks. Pre amp out from the Sansui to the input on the EQ then the EQ out back to the main in on the Sansui. That way everything you select on the Sansui will be equalized. My EQ has a power switch and an EQ on or off button. That way you can leave the EQ on but bypass equalization when you wish to. Hook the EQ to the switched outlet on the Sansui and just leave the power on. When you switch the ereceiver on the EQ, of course, will come on too.

    The EQ will have a tape in and out on the back. That is because if it were used with a receiver without pre in/main out jacks you would have to connect it to the receivers tape loop. The tape loop on the EQ was to give a substitute for the one you used. I suppose you could use it also in addition to the 2 that the 9090DB already has?

    It is good to note that the 9090DB has a second preamp output on the back (I am Pretty sure because my 8080DB does). This is nice to have if you want to run a sub that works independently from the other full range speakers you have hooked up. It of course would be nice to send to another amp also. Just food for thought! Good Luck! Franksta
  5. Autobot

    Autobot More than meets the eye


    Frank is correct.
  6. EchoWars

    EchoWars Hiding in Honduras

    Kansas City
    Put it in the tape loop where it belongs. You'll destroy your S/N ratio by putting it between the preamp and amplifier. Why?

    The average signal level sent from the preamp to the amp is very low. At normal listening levels, this signal is well under 100mV (0.100V). This is down in the gutter, as we consider the signal vs noise levels of the EQ device, and way too close to the noise floor of the EQ itself. But both this noise and that weak signal are amplified by the power amp just the same...most power amps have a fixed gain of about 20db, so consider that you have just raised the noise floor of the EQ device by exactly the gain of the power amp...not good!! If someone said, "Pssst! I have a device here, for free, that's guaranteed to reduce the noise of your system by up to 20db!" would you be interested? You'd be a fool not to be. And this 'device' turns out to be nothing more than the instructions to move four interconnect cables. :thmbsp:

    Look at it as if you were setting the record level on a tape deck. There's a reason you record at the highest level you possibly can...your noise floor is fixed, and you're trying to elevate your signal level above this noise floor as much as possible without saturating the tape. This idea of keeping the signal level as 'hot' as possible to reduce the perceived noise when recording to tape is a perfect analogy for why you'd want to do the same thing when passing the signal through an external signal processing device, such as an equalizer...the noise floor is 'fixed', and we want our signal as 'hot' as possible through the device to reduce the perceived noise that is added by the device itself. This is a core idea in all signal processing, or else giant mixing boards in the recording studios wouldn't have banks of LED's or analog level meters to assist engineers in setting signal levels...if it doesn't matter, why bother with level meters at all?

    This is why the equalizer should be added to the tape loop (tape monitor) connectors, as the unattenuated signal level there is MUCH higher (10~20db and more) than the weak signal that is passed from the preamp to the amplifier. Don't believe this? Connect the 'Tape Out' jack to the 'Main In' jack of the amplifier (OK, don't do this, as you'll probably drive the amp into hard saturation and blow the amp or your speakers or both).

    And it's not like it's a secret....equalizers for home audio have tape monitor facilities built into them because they are meant to go into your tape monitor loop, and the monitor functions on the EQ are there to replace those that are lost by using the loop for your EQ device.

    This is your equipment, and you should do as you like. But, the AK forums are not about listening to Soundesign or York other worthless BPC, we're into real High-Fidelity gear here and helping others to maximize their enjoyment while minimizing their investment. And although there's a right way and a wrong way to get many things done, sometimes there's 'a way that will work', and 'a way that works a lot better'. Tweaking your setup to get the highest possible performance out of it means finding 'a way that works a lot better'.

    For an EQ, that means putting it in the tape loop, for the reasons I've outlined above.
    gtv2000 and chodad like this.
  7. Franksta

    Franksta AK Subscriber Subscriber

    Thanks Echowars for that info! I surely wouldn't want to misguide someone!

    I recently hooked a new amp (Pioneer SA-7100) to my computer system. I also had a nice SG-9800 EQ laying around so I decided... Why not use it? I have definitely noticed that when the computer is selected as the source that there is a lot of noise incorporated into the signal. I was blaming it on the new Diamond soundcard I recently installed which I am sure has a certain degree of noise but this was just really disturbing. I will be pulling that EQ out of the system and putting it back on the shelf. I really didn't need it there anyway. It was just for looks and it gave me a chance to use a piece that had been sitting unused.

    I always thought that using the tape loop was the compromise and that running the EQ through the pre/main if available was the more "direct" route. I never considered the noise issue. Thanks!
  8. jdandy

    jdandy Super Member

    EchoWars........Very well said. And very true!
  9. michaelhigh

    michaelhigh mind's eye music

    Lenzburg, IL
    This is a thumbnail sketch of what I meant by gain structure. It involves headroom to avoid amplifying noise and increasing clean signal instead. Thank you once again EW.:yes:
  10. ryuuoh

    ryuuoh FFXIV Summoner Subscriber

    Marina CA, USA
    This subject has been coming up a lot recently. I vote for a sticky.

  11. sb47

    sb47 Well-Known Member

    Tape loop.:thmbsp:
  12. minkybut

    minkybut AK Member

    This is the best explanation I have ever read. It should be included in "The Book of Great Stereo Issue Fixes" or something like that.

  13. melofelo

    melofelo Addicted Member

    london, uk
  14. Cwalter

    Cwalter New Member

    How to set up Sansui 9090 without Tape Monitor?

    Hello All---

    First post here, but I've been reading for a few months ever since my big bro (finally) gave me his Sansui 9090 that I'd been oogling since oh, around '76.

    Anyhow, I'm thinking I may want to hook up a nice vintage EQ but am baffled as to how I should do this since the 9090 does NOT have a Tape Monitor button?

    If I go ahead and put in an EQ I'd like to have all my inputs (CD/Aux/Phone/Cassette/FM. etc) running through it, not just the ones tied into the tape loop.

    How can this be done, or am I just missing something simple?

    THANKS everyone, your expertise and advice is greatly appreciated!!

    Chris W.
    Modesto, CA
    Sansui 9090
    Technics SL-Q200
    Denon DRW-660
  15. oblomov

    oblomov Well-Known Member

    Alexandria, Virginia
    from looking at photos of the 9090, it looks like "Deck 1" is one tape monitor loop and "Deck 2" is the other. I'd connect the EQ as Deck 1 and when you move "Tape Play" to Deck 1, it should engage the EQ as a typical tape monitor in/out button does (?)

    I could be wrong, as I've never actually owned one of these...
  16. EchoWars

    EchoWars Hiding in Honduras

    Kansas City
    The 'Tape Play' selector switch does the tape monitoring duties on the 9090. In the center position, you monitor any source that the 9090 might be playing...a CD plugged into the Aux jack, the FM tuner section, or the Phono stage. Any of these inputs is automagically fed into the tape loop (both Tape 1 and Tape 2) whether you have a tape deck connected or not. This signal is tapped before any of the preamp functions (tone, volume, balance, etc...), only the phono has an active stage at this point. Thus, it's an ideal place to grab the signal for any processing.

    So...connect the Tape 1 (or 2, doesn't matter) 'Rec' jacks on the back of the receiver to the equalizer input, and the 'Play' jacks on the receiver to the equalizer output. Select 'Deck 1' (or 2, depending on which you used) with the 'Tape Play' selector switch and if you have the proper monitor button selected on the equalizer unit, you should be good to go.
  17. Cwalter

    Cwalter New Member

    Thanks oblomov and EchoWars for your quick responses.

    EchoWars: I must be missing something... If I always have the Tape Play selector set to Deck 1 (assuming the EQ is set up through there as you described), how would I play from AUX or even Deck 2, while still going through the EQ?

    (Sorry, I don't have an EQ yet so I can't really test this out)

    Thanks again for your assistance...
  18. tmtomh

    tmtomh Active Member

    PA, USA
    EchoWars, a question, probably an obvious/stupid one, but...

    What you say about hooking up an EQ in the tape loop instead of via the pre-out/main-in - that applies only to receivers and integrated amps, yes? If you have separates then it doesn't make a difference because no matter what, the EQ is going to be in the signal chain before the pre out stage - right?
  19. whoaru99

    whoaru99 Epic Member

    Connecting the eq between the pre amp and power amp in separates is the same as connecting between the pre out and main in on a receiver or integrated.

    Or, put another way, regardless if separates or receiver/integrated, it's better to put the eq in the tape loop.
  20. tmtomh

    tmtomh Active Member

    PA, USA
    I understand that connecting the EQ between pre-out and main-in is the same whether one is using separates or an integrated/receiver.

    But my question concerns the other option: connecting the EQ in the tape loop.

    If you have separates, connecting the EQ in the tape loop will of course allow you the option of taking it entirely out of the circuit when you don't want it there (as opposed to leaving it in the chain but just pushing the bypass switch on the EQ).

    But in terms of the noise-floor/SN ratio aspect, how could putting it the tape loop improve that when you have separates? By definition, a tape loop connection on a preamp still comes before the pre-out. But with an integrated/receiver, the tape loop could conceivably be located AFTER the pre-out in the signal chain - in fact, it would have to be in order for there to be any noise-floor improvement over putting it in the pre-out jacks.


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