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Tube amp fireworks!

This happened a few weeks ago.  I had just sat down to listen to my second reference system .  I built it with some vintage but super high end gear.  I  powered up and gave the amps a few minuets to come up to temperature. Drop the stylus and after a few notes a horrendous scratchy static comes out at full volume! Like holy fucking shit volume!  I immediately power down and notice smoke coming from the driver tube area on the power amp.  Something seriously wrong just happened! I’m not exactly sure what but I do know it was bad. Since I’m still new at the repair hobby and because this amp is really nice I decided to take it to someone who’s worked on them before.  I didn’t want to risk turning it into a doorstop and the voltages in it are frankly terrifying.

Just found out today the extent of the damage and I think I’m pretty lucky!  The previous owner changed the fuse from a 2 amp to a 7 amp so it could have been really really bad.  John the tech thinks that I might have accidently shorted out the leads and caused this shit show. 🙂  I can’t say for sure but it seems passable since I’m using spade lugs and not banana jacks on my speaker cables.  The binding posts on this amp are also all metal making it even easier to cause this type of failure.  John sent me pictures of the damage and it looks like I smoked a few parts in the driver section but its not that bad  thankfully and fixable!  It’s getting repaired now and I should have it back in two to three weeks.

John tested all the tubes and found that my power tubes tested pretty bad.  Two of them are actually really really bad which has me a bit bummed out over.  They are all relatively new PSVANE KT88’s.  This is my first time dealing with Chinees tubes so I don’t know what I can expect in terms of life expectancy but I hoped for over a year. They did get good reviews online and I really loved the sound but I decided to order a new matched set of 8 Sovtek 6550we’s.  I tried KT88’s and know the sound signature pretty well so now I’m excited to see what 6550’s will do to the sound and I know Russian tubes will last much longer.

Well that’s about all I have for today.   Happy listening!

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Bucking Transformer

I built a bucking transformer for use with older tube amplifiers. Did you know that back in the day the voltage in the US was 110v!  Yeah who knew!  Its in the mid 120v range hovering around  123V-124V in my house in NJ. I have CT’s logging the power at my main breaker in my main panel so I have a log of this over time. This higher then design voltage takes it toll on old transformers and components. It can cause the bias voltages on the tubes to be higher and leads to tube wear and premature failure that I want to avoid.  I can buy an off the shelf step down transformer or variac’s but they are expensive, big and ugly. It’s also no fun!  I decided to go the DIY route and use a small 12v AC transformer to buck the voltage. The transformer I’m using is a $40 fairly cheap 12v center tapped one off Amazon. It’s not some exotic crazy expensive transformer hand wound by Franciscan monks with silver wire built somewhere in Europe.  The trick is to wire the secondary out of phase with the input voltage on the primary.  If you do this properly the two voltages will subtract from each other and you get the following:

      • 120V – 6V = 114V
      • 120V – 12V = 108V

If you wire it in phase you will get the opposite.  The voltages will add together and you will get a higher voltage.  This is called a boost transformer

      • 120V + 6V = 126V
      • 120V + 12V = 132V

This is a pretty neat trick and pretty cost effective.  You don’t need such a big ass transformer because it’s not handling the full voltage of the load! Pretty cool right! If you would like to know more let me know and I can post pictures and a wiring diagram to help you build your own.  I mounted it in a small metal project box I got off Amazon.  IEC inlet on one side and regular household receptacle on the other side. I removed the tie on the hot side of the receptacle and wired it so that one plug is at 114V and the other is at 108 making it pretty versatile.  I grounded and fused it as well for safety.  I find it runs cool while powering a Dynaco ST-70 for hours.

Well time for bed.  Happy building!

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Labubu!

My girlfriend got me a Labubu! One of her vendors brought him from China. She opened the box with me on the phone so I know his color! 😬 He’s in LIC so I need to head over for the weekend and see. Love his toothy mouth and naughty grin like he’s gonna do something.

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Hit another deer…

Hit another deer on the way home from Nutley Thursday.  This is the second time with this car.  First time was under 3k miles on the clock and this time it just turned 1 year old.  Anyone want deer jerkey, burgers or hot dogs?! I’m getting my retribution this hunting season for sure. Going to work on getting my bow hunting skills in place this year so I have a longer season. Better watch your back Bambi… RJ and I are coming for you.  🙂

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Dirac Live on MiniDSP

I know this is sacrilegious in audio circles but I decided to put a MiniDSP between my source and pre-amp in my desktop nearfield listing rig.  It makes a huge difference, like not subtle it’s huge!  You can easily A/B it by disabling Dirac on the MiniDSP.  If you have anything that can do Dirac room correction you owe it to yourself to just give it a try.  You will need a calibrated mic, mic stand and and about an hour to run the software and place the mic around the room.

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Tove Lo

Just picked up Tove Lo’s Sunshine Kitty and Queen of the Clouds albums on vyinal. I’m a huge fan of her music and her attention to the quality of the pressings. Absolutely stunning sound on vyinal. I also picked up a used copy of Was (Not Was) “What up Dog?” so I can have a copy of Walk the dinosaur! Used to love that song. Probably going to play Lights A6 album next. Got a first pressing and she signed it as well. 😬 I have some of here test pressings in my collection too. She’s another artist that really cares about quality.  Anyway time to get back to listening.

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Record cleaning

I have been trying to come up with the perfect process to clean records. I think I found it! I was thinking about one of the fancy ultrasonic cleaners but what I found is perfect. Here how I do it if your interested.  First you are going to need a few things. One is kinda pricy but not anywhere near a ultrasonic unit.

      1. Okki Nokki record cleaning machine (any vacuum style cleaner will work here)
      2. Okki Nokki record cleaning solution
      3. Revolve record cleaning solution
      4. Distilled water
      5. ClearAudio cleaning brush
      6. Revolv goat hair cleaning brush
      7. Small spray bottle.
      8. High quality microfiber cloth
      9. Milty Zerostat
      10. DS Audio ST50 stylus cleaner
      11. Mofi Master Sleeves
      12. Mofi Archival Sleeves

This process will make the vyinal dead quiet with almost no pops and clicks. It does involve a bit of work but I find it enjoyable.

Step 1
Make sure the platter on your Okki Nokki is clean and dust free. No sense in putting a record on a dirty platter and pressing that dust in the grooves. Place your record on the platter and tighten down the record clamp.

Step 2
Add distilled water into your spray bottle and wet your brushes. Both the Revolv goat hair and the Clearaudio brushes. Don’t put them on the record dry.

Step 3
Start the platter in CCW direction on the Okki Nokki. Add the Okki Nokki cleaner to the surface of the record. Now use the goat hair brush. When I see light bubbles I change directions to CW and start the vacuum. Suck up the dirty fluid and add fresh. Brush again with the goat hair brush until you get some small bubbles.  Once you do vacuum up the solution.

Step 4
Do the same thing as step 3 with the Revolv solution. You will not get bubbles however. Use the ClearAudio brush. You will notice that the he water doesn’t bead, it sticks and spreads out.  Do both directions and vacuum between directions.

Step 5
With the Okki Nokki platter spinning CW spray the surface with a light coat of distilled water then vacuum it up. Remove and repeat step 1-5 for side 2.

Step 6
With record off the Okki Nokki hit it with the ZeroStat gun I give 4 trigger pulls. One in the center about 6 inches away, and then a triangle starting at the top, then left then right. Now it’s ready to play.

Step 7
Before you play clean your stylus with the DS Audio ST50. Place it on the platter and drop the arm into it twice.  Now you are ready to listen. Enjoy the fruits of your labor!

Step 8
When done listening place your record in a mofi master inner sleave and put your jacket in a mofi archival sleeve.  I slip the inner sleeve in the back of the jacket to prevent ring ware.

That’s it. If you try this let me know how it goes! Happy listening.

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Dynaco ST-70 listening impressions

Got this old girl all warmed up and just had a good listen to it. First impressions is this is not a modern amp. I listened to some Tasha Sultana and boy does this amp pair well with her type of music. Absolutely beautiful, smooth warm and holographic sound. Very good match. Going to listen to some more electronic music and see how it does. I get the feeling it might not do as well. Will report back but I need to power it down now. It’s hot as balls in here now!

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Dynaco ST-70 project

Just got a crusty old Dynaco ST-70 tube amp off e-bay to rebuild. It’s a project I’ve wanted to do for a long time. It’s amazing that you can still get replacement parts for something so old. The unit I got is in good shape electrically, but needs a new chassis. The chrome is old and pitted with rust here ans there. The output transformers also need a nice coat of paint  too.  Going to listen to it for awhile then do a transplant into a new chassis. It will. Give me the opertunity to replace older components while I’m in there.

I have been looking over the schematics and it’s a really simple design. Elegant simplicity that has stood the test of time. Will take some pictures when I get the chance. Plan on using it on my main workstation. Currently using an Emotiva integrated amp but I think it’s more interesting to use a preamp and amp here. Going to use a cheap Schitt amp for now and maybe get a vintage Dynaco pre-amp to rebuild later on down the road. I have also been eying a Dynaco Stereo 400’s on e-bay but that’s way down the road.

Want to get more into repairing old vintage equipment. Might hit some estate sales and garage sales this year and see what I can find… Not much in terms of deals in e-bay… Most people know what they have. Someday maybe a Sanusi AU X11! That’s a grail for me. Anyway that’s enough for now.

Dynaco ST-70