Recent Posts

21

Crack / Re: Choke specs for the Crack

« Last post by trollchu on May 18, 2025, 03:14:00 PM »

That's all quite reassuring to hear. If so, I think I've mapped out all my mods then, minus the pot.

The 100uf Wima's are cool cause they're still significantly smaller than a lot of other film caps, and for the third position, four of them side by side only take up 4.88 inches. They are the automotive grade Wima's, which are still polypropylene film and low ESR; they're also cheaper than 100uf Audyn caps right now. What I'm planning to do for those is to mount them to a sawed off piece of a clipboard and mount them on standoffs just like the chokes,  but I still need to check and confirm the height of the Wima's versus the height of the Crack, I want it all to fit under the wood chassis if possible.

It's a crimson red Crack build, with all the Wima's it'll be red inside, too. Thanks again, Paul.

22

Kaiju Stereo 300B amp / Re: Difficult to Reproduce Issue

« Last post by Doc B. on May 18, 2025, 01:33:58 PM »

That's a bad connection somewhere. Cleaning pins as suggested is a good place to start. If that does not resolve the issue you may need to power up the amp with tubes in it and check the voltages. If you find that some voltage is not coming up properly you can start to check the left channel circuit for suspicious solder joints.

23

Otari Tape Path Kit / Re: Tape path bearing noise

« Last post by Doc B. on May 18, 2025, 01:30:07 PM »

The only time I have heard of that happening before was when a customer had been cleaning the tape guides frequently with alcohol. That can wash the lubricant out of the ball bearings. You could try removing the bearings and soaking them in some light oil, or simply replace them with new MR63ZZ bearings of an ABEC 5 or higher tolerance rating.

24

Kaiju Stereo 300B amp / Re: Difficult to Reproduce Issue

« Last post by Thermioniclife on May 18, 2025, 12:18:00 PM »

Did you swap the tubes and see if the problem follows the tube? I say that as you said that all your voltage tests are good, perhaps checking the resistance checks would be in order. also I think you should clean the tube pins and socket pins with an electronic cleaning solvent.

25

Kaiju Stereo 300B amp / Difficult to Reproduce Issue

« Last post by ashbrook.m on May 18, 2025, 11:54:13 AM »

I have been using my Kaiju with both upgrade kits for the past few years with a weird issue I cannot seem to chase down.  The left channel has always taken a little longer to warm up but every few months it will take 5-10 minutes before an audio signal passes out on the left side. It will come on with a “pop” and then work perfectly for months.

Swapping outputs shows that the issue is only with the left channel. The heaters are glowing on all tubes. I cannot tap on either left chanel tube and get any microphonics when it’s not working. By the time I get it down to my bench and check voltages, they all are in spec. Any thoughts on this?

26

Otari Tape Path Kit / Tape path bearing noise

« Last post by ReelNutz on May 18, 2025, 08:28:23 AM »

Hi, Everybody!

Got an Otari Mx5050 Bii last fall with the tape path upgrade.  There was always a bit of noise from tension arm rollers, but it has gotten louder.   So much in fact that it is a distraction when playin at lower volumes.

Is there regular maintenance required to keep this from occuring?

Much appreciation fer any advice anyone has.

27

Crack / Re: Choke specs for the Crack

« Last post by Paul Birkeland on May 18, 2025, 07:46:41 AM »

There isn't much concern about a power supply choke and a power transformer interfering with each other.  All those Wimas will take up a lot of space, that's the only issue I can think of.  Bypassing caps was pretty popular around 1995-2005, but power supply caps have improved, and the technical merits of adding bypass caps have become dubious at best.

28

Stereomour II / Re: Failed Final Voltage Check

« Last post by Paul Birkeland on May 18, 2025, 07:44:51 AM »

A backwards cathode bypass cap around the 2A3 socket on that side would also cause similar issues. (the 220uF/250V by the socket)

29

Stereomour II / Re: Failed Final Voltage Check

« Last post by figby on May 18, 2025, 05:32:53 AM »

The resistor between 27L and 30L is indeed cooked...thank you!

I double checked and I hadn't plugged in either 2A3 incorrectly, so that's a bit worrying that the issue might be hidden somewhere else. In the meantime, I'll put in a request for some replacement 130 Ohm 2W resistors and continue to check the circuit for possible shorts or mistakes until they arrive.

30

Crack / Re: Choke specs for the Crack

« Last post by trollchu on May 18, 2025, 02:12:39 AM »

I'd more love to see to see how someone'd plan to fit it all that in a Crack build, a dual mono power supply with three chokes sounds like a job for a master craftsman.

I have a couple more questions. I'm still in the midst of painting my Crack and the paint I'm using needs three weeks minimum drying time for best results, so I've got a lot of time to plan the mods I'd like to implement in my build. I'm planning to go with two Hammond 158M chokes on 1.5 inch spacers so that they still fit within the wood base and I'd like to mount them above power supply caps one and two. When it comes to mounting chokes, is there a way to insure that my placement of them won't cause inference with the PT-10, and can I test for that somehow?

These other questions are a bit off-topic for this thread, but for the third power supply cap, as well as both sides of the output caps, I'd like to run 100uf Wima's and I'm considering using four Wima's in parallel in place of the third power supply cap and two Wima's per side on the output. Would I run into any issues in running paralleled caps in any of these positions?

Lastly, what benefits are there to be found in bypassing power supply caps and what are some good options for a stepped attenuator in 2025?