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Posts posted by Limberpine

  1. 1 hour ago, billybob said:

    Can you get too the servo without having to dismantle alot.

    Curious to see this often talked about servo.

    The servo controller box as well as the subwoofer box are very easy to open and take a peak inside.

    • Like 1
  2. Well the mechanical hum of the servo controller has gotten worse and the popping is becoming more frequent again....... 


    I'm going to start considering other options. One question I have, is a horn loaded servo controlled sub a thing? I really like the tightness of the Velodyne servo controlled bass.


    Or if I considered the La Scala mod for the ported stand would that be a good replacement for a sub, or will that just still be lacking? There are some songs where I really enjoy that bass hit, like I'm at a conference and also other songs where I like hearing that down low growl in vocals that comes from artist like Captian Beefheart and Guy Clark. 


    Thanks for any help or suggestions! 

    • Like 1
  3. 3 hours ago, ClaudeJ1 said:

    Seismic Sub, as I have too many subs already, but it's too soon to tell. 107 db/W sensitivity is hard to beat.

    Which Seismic sub do you have? 

  4. 4 minutes ago, RandyH000 said:

    these are not  STUDIO LA SCALAS ,  these are Industrial Lascala splits  rated at 200 watts with a k43 woofer instead of a K33 and a terminal cups with fuse holders  for  the HF and LF , the drivers from the HF  come out from the front by unscrewing  a panel----duratex style finish , they are missing both klipsch industrial badges -on the top hat and the bass bin -



    Is there a "Studio La Scala"? 

    • Like 1
  5. 37 minutes ago, MeloManiac said:

    Your hum issue continues to be on my mind. The thing is that the Dynaco ST70's topology is quite symmetrical (compared to the asymmetrical topology of the Leben CS300).

    So I found this information about it elsewhere, and it comes from Bob Latino, who has a great reputation related to ST70 tube amps. 

    Your hum may be caused by not incorrect bias. You should be able to check this on your own. This may have been metioned earlier on in this thread, but I heaven't read all 8 pages....




    New to the forum.... Gifted an ST70 w/KT88s, VTA w/12AT7s. Amp is dead quiet with no input cables. When preamp connected, no hum at minimum volume, moderate hum starting about ⅓ on volume, louder as volume is turned up. Balance control moved to the left, hum on left channel disappears, to the right, hum remains. As soon as it is moved towards the center, hum on both channels. When a record is played, volume is equal from both speakers (AR2a). Rolled 12AT7s and got hum with balance full left or right. Also need instructions on how to bias as no documentation was received.... (Gregg)

    Hi Gregg,

    If your VTA ST-70 is quiet with no input cables OR with the input cables connected to your preamp and the preamp on at minimum volume then the amp is not at fault .. It is your preamp that is at fault.

    To bias an older 12AT7 driver board VTA ST-70 see below .. NOTE - The older VTA amps with the 12AT7 driver tubes have the bias pot's rotation in reverse > clockwise rotation will DECREASE bias level and counterclockwise rotation will INCREASE bias level.

    Get your multitester and set the range for 0 to 2 volts DC. CONNECT THE SPEAKERS. Place the GZ34 rectifier tube and just the LEFT EL34/KT88 output tubes in their socket. Turn on the amp. Allow the amp to warm up for a minute and check to see that the EL34 and GZ34 tubes light up properly. Measure the bias on the LEFT output tubes by placing the BLACK NEGATIVE probe anywhere on the chassis and the RED POSITIVE probe in the hole marked “Biaset 1.56 v”. With a small screwdriver adjust the FRONT LEFT bias adjuster on the driver board closest to the front left tube. Turn the adjuster CLOCKWISE TO REDUCE BIAS and COUNTERCLOCKWISE TO INCREASE BIAS. Set the bias for .400 volts if you are using EL34 or KT77 tubes OR .500 volts if you are using KT88 or 6550 tubes. Now place the positive probe in pin 4 (which is on the opposite side of the power take off socket) and use the BACK LEFT bias adjuster to measure bias on the LEFT REAR output tube. Set it the same as the front tube. Turn off the amp. (Note - on some amps the REAR output tube's bias measuring point may be on a different front tube socket pin) Plug in the two RIGHT channel EL34/KT88 tubes, turn on the amp and repeat the bias procedure as outlined above on the RIGHT channel tubes. Now go back to the left channel tubes and notice that the bias is now a little LOW. ADJUSTING BIAS ON ONE TUBE HAS A SLIGHT AFFECT ON THE OTHERS. Go back and forth between all output tubes until all tubes have the proper bias.

    Bob [Latino]

    This was not previously mentioned in the rest of the thread. Thanks! 


    I have never set the bias on the St-70, the last tube amp tech I had check it out, reset it with the newer tubes I got for it. I'm running a NOS GZ37 and new Tung Sol El-34s and NOS RCA 7199 blackplates, in that amp right now. I will admit its a bit daunting to me to take this bias adjustment on, cause I don't want to ruin anything, but I also want to learn more about all of this, so I will find some time to try out what Bob Latino suggests


    The ST-35 doesn't have bias pots and James Burgess PP 45, this is what James told me There are no bias adjustments. It is set up so the AC(signal) balance of the phase inverter can be adjusted.  This is only necessary when changing/replacing the 6SN7 tubes. 


    All the tubes in the James Burgess are NOS and close matched. 


    I listened to the PP 45 last night and ignoring the noise, the sound was divine. 


    Thanks for your thoughts and help!

    • Like 1
  6. 2 hours ago, MeloManiac said:

    It was enough to solder a few resistors to the headphone socket, and that was it. Their values must be chosen experimentally, as it will depend on the impedance and efficiency of our headphones. At first the values were chosen too big, and needed to be adjusted, but now I can tell, that there is no hum at all! And no noise. This is the reason I recommend this simple trick to everyone – it is cheap and effective. Probably in the future I would like to see better resistors there, like Vishay, but for now, I am happy.

    source: http://highfidelity.pl/@main-135&lang=en

    So, should I look into placing some resistors across the speaker wire connects on the crossover? Would that help? 


    But, Yeah, I guess I will learn to live with it.....for now.....


    Thanks for your help! 🙂

    • Like 1
  7. Welp, I turned off every circuit in the house except the one that the stereo system is on and the buzz still persists. What's weird is that my SET amp doesn't have the buzz, it has a dull hum up close, but all of my push pull amps have this same buzz. 


    Video attached of the sound from 3ft away from the speaker. Headphones are helpful to hear it, because of taking the video from my phone. 

  8. 6 hours ago, PED said:

    Hello Tinnitus, yes I would be willing but I have no idea what that would cost. Was hoping I might get lucky and find someone fairly close so we could do an in person transaction. I know I am leery of buying something sight unseen, and relying on someones own assessment of what they have.

    I sent you a PM. I see you are close to me, I'm in Portland, OR.

  9. 3 minutes ago, billybob said:

    Yes, based on the noise, that would be a cool idea. While about it, if the same while other breakers off, may be a good time to troubleshoot the dimmer switch and any other idea.

    Cool, please let us know.

    Yeah, that's a good idea. Maybe I will take both dimmer switches out too to see what difference it makes. The one that is on the same circuit certainly makes a difference when its turned off and it stays off whenever I am down there listening to music. 

    • Like 1
  10. I have a window this evening where I can shut down every breaker in the house except the one that the stereo system is on and see if that make a difference. If so, I will then document which breakers introduce noise as I turn each one back on and go from there.


    I have also added a Powervar hospital grade power conditioner/isolation transformer that I purchased for $60 from a guy here locally. I have the tube amps plugged into it and it has definitely cut some noise out which has been nice.

    Also as an aside, GIK has a really cool tool to draw your room out and then have them make a treatment plan from there.





    • Thanks 1
  11. 9 minutes ago, geoff. said:

    Nothing says “Here To Rock!” like the PWK logo’d woofers on some of the pro stuff.


    I balked on a pair of KP-250s years ago because I already had Heresy 2s.


    When I heard them demo’d at the seller’s house they were nothing short of remarkable for such a small package. 


    If they were aestheticlly pleasing, I would buy them right now, cause it could replace the Cornwalls in the living room, which I am politely being encouraged to do because of their size. Then I gotta find a place  for the cornwalls! 🤣

    • Like 1
  12. 28 minutes ago, RandyH000 said:

    you dont need to replace the tweeters ,all you need are 2 diaphragms ---so 2 options ------phenolic or titanium --


     K75-K76-K79 and pretty much all the tweeters made by klipsch  for the past + 35 years -share the same diaphragm ---


    FS - Klipsch K-79-K Horn Speaker - $50 - Garage Sale - The Klipsch Audio  Community

    Thanks! I wish I could even justify having a use for them. And it seems like they are a bit hard to resell cause nobody has picked them up yet. 

  13. 6 hours ago, RandyH000 said:

    --if you used the k77  's in the KP 250------ you'd be blowing tweeters all day long    - 

    Which tweeters would you have to use and how much do they cost? 

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