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Tannoy Monitor Red 15 crossover question

Discussion in 'British Audio' started by litefootdan, Jan 28, 2018.

  1. litefootdan

    litefootdan AK Subscriber Subscriber

    Messages:
    358
    Location:
    Shawnee, KS
    I've been thinking of replacing the crossovers in a pair of Monitor Reds that I've had for awhile and I've come across a schematic on this website...

    http://www.44bx.com/tannoy/TannoyXos.html

    Screen Shot Tannoy Xover.png

    This is what the schematic looks like.

    Has anyone had any experience with the Monitor Red crossover and can anyone shed light on whether this schematic is a viable guide for me to follow?

    Also, if anyone has any recommendations on components I'm all ears. I'm thinking of Goertz copper film inductors but haven't come to a decision on caps and resistors. And for what its worth, Im not sure whether or not to include the "un-official" HF response modification near 3KHz.

    Any and all help is greatly appreciated.
     

     

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  2. louisjames

    louisjames The "real" Louis James Subscriber

    Messages:
    2,022
    You might want to post on Pink Fish Media in the "Classic" forum and on Art of Sound. There are some very adept folks there who can provide guidance and I found it was a great help when my Tannoy's started acting up. I went back and forth on this for my GRF's with MG 15's and after all was said and done cleaned up the connectors on the stock ones and left things as is. Good luck with whatever you decide. Monitor Reds are a wonderful thing to have! :)

    Have you seen this post?

    http://www.intactaudio.com/forum/viewtopic.php?t=1018

    And this - although it's specific to MG's -- Black Adder, who is a moderator there is supposedly a Tannoy wizard.

    http://theartofsound.net/forum/showthread.php?21172-Tannoy-Monitor-Gold-crossovers
     
    Last edited: Feb 25, 2018
  3. litefootdan

    litefootdan AK Subscriber Subscriber

    Messages:
    358
    Location:
    Shawnee, KS
    Thanks so much for your input.

    I hadn't known of Pink Fish Media before your suggestion.

    At some point I had come across the first link you listed. I just didn't pursue it as Dave never really expanded on his satisfaction or lack there of.

    I suppose I should consider messaging Black Adder but it might be too late. I have done a bit of talking with Chris over at Jupiter Condenser Co. We mulled over some copper foil inductors I was considering going with and using his copper and wax caps..... The money's already been spent ;) I'll probably go with Dueland resistors and have a go of it.

    I sure hope it's worth the time and resources, the speakers really do sound wonderful with their original crossovers. But I can only know if I give it a shot. I've been running them with some unassuming amps with incredible satisfaction. A long time ago I built a pair of ZKIT1's (turned to monoblocks) and they did short order duties when I was fooling around with less than optimal speakers for their abilities. So they sat unattended for too long. But on a situational whim I have them mated with the Tannoys and the combination is sort of spellbinding. And it seems to get better the longer I listen.

    What ever the case, I am going to try to document this crossover build and post it.

    Again, thanks Luis,

    Dan
     
    Last edited: Feb 26, 2018
  4. litefootdan

    litefootdan AK Subscriber Subscriber

    Messages:
    358
    Location:
    Shawnee, KS
    Just an update on the crossover build. I went with Jupiter Copper Foil Paper and Wax capacitors, Goertz 14AWG copper foil inductors, and Dueland Cast resistors. Essentially I am copying a rebuild I saw on a blog named Jeff's Place. (google search dueland tannoy crossover if curious) He went whole hog. I can't afford the Dueland caps but I'm doing what I can. I haven't heard anything I like better than the Tannoys I have, so I thought why not throw the best components I can afford at them. I liked the idea they had over at Jeff's Place, to use copper set screw lugs for termination. Mostly because I am afraid to solder components in the hundreds of dollars together. But any way, I'll make sure I do some sort of documentation on the crossover build.
     
  5. litefootdan

    litefootdan AK Subscriber Subscriber

    Messages:
    358
    Location:
    Shawnee, KS
    IMG_E3208.JPG
    Here's an update on my rough-in for the crossover rebuild of the Tannoy Reds. The high frequency section is up top and the low frequency section is down low. I went with a 30Ohm resistor instead of a rheostat. I have no way of know what the efficiency of the compression driver is in the Tannoys, but I hooked the crossover sections up to a pair of box-less Altec 402c's this evening. The highs seemed suppressed... I guess I'll have to hook them up to the actual Tannoys in their cabinets to get a feel for what is actually going on. But at least I know the dividing networks are dividing ;) I'm going to reproduce the crossover and hook them both up and see if I need to adjust the resist in the un-official mod section of the crossover.
     
  6. litefootdan

    litefootdan AK Subscriber Subscriber

    Messages:
    358
    Location:
    Shawnee, KS
    IMG_3212.jpg
    Gonna hook them both up this evening and see what happens, fingers crossed.
     

     

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  7. homebrew

    homebrew Active Member

    Messages:
    225
    It looks to me your inductor in the wooder circuit is not connected correctly. One of the leads from the inductor is connected directly to ground with the large capacitor lead.
     
  8. litefootdan

    litefootdan AK Subscriber Subscriber

    Messages:
    358
    Location:
    Shawnee, KS
    Wow! How correct you are.

    I've corrected the mistake on one channel. Thank you very much for pointing it out. I had been listening to these crossovers on the Tannoy drivers but only with ~2.4 watts per driver for about a week. I've only corrected one of the crossovers to see how it was different from the other still incorrect crossover. The difference is not glaringly evident.

    Because I don't understand crossover theory I'd like to ask a couple questions. In the picture above, the low frequency section of the crossover had the inductor going to ground with the large capacitor- what in theory was happening to the signal headed to the woofer?

    Now that the inductor is in series with the on the positive side and the large capacitor runs parallel after the inductor, what is happening to the signal headed to the woofer?

    Thank you very much for pointing out my mistake and I appreciate any insight you can offer me as I learn about crossovers.

    Dan
     
  9. homebrew

    homebrew Active Member

    Messages:
    225
    In your original crossover diagram, the 4mH inductor is connected in series with the positive input of the woofer. The inductor acts as a low pass filter (allowing only low frequencies) to pass through to the woofer. The 18uFd capacitor is shunted to ground to form a second order electrical filter. Note the capacitor connection on the OUTPUT side of the inductor.

    Here's a crossover tutorial that will explain it better.
    https://www.audioholics.com/loudspeaker-design/crossover
     
  10. litefootdan

    litefootdan AK Subscriber Subscriber

    Messages:
    358
    Location:
    Shawnee, KS
    Thank you homebrew. I will do my best to wrap my brain around the information you've linked. I appreciate your insight.
     

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