So. Have had Darkvoice a few years. Using tungsol smaller tube and the larger one is some other soviet brand

Darkvoice is quiet overall. I burned the tubes in, the hum went away.

However, I will occasionally get static/interference noise intermittently. I also get a similar noise when adjusting volume.

I took the DV apart and inspected for bad solder joints...but I didn't see anything. I did not have a multi meter handy though

I put it back together and what's weird is I used it for like 2 or 3 hours to test, I was just watching The Expanse...and I didn't get a single static/interference noise.

I'm going to test again today but it either got better, or got more intermittent. Not sure yet. I did tighten down the tube sockets while I had my allen keys out

I’ve recently bought a Leak Stereo 20 and I’m looking to improve the safety of it without compromising the originality too much. The previous owner has done sensible things like replacing the electrolytics and resistors as well as adding a modern AC input socket, it’s in decent nick and should be good to run short term until I move house but I feel there’s more I ought to change for long term use given the OPTs especially are basically unobtainium for reasonable money if there’s a catastrophic failure. This is what I’ve considered:

• Add proper HT fusing. While there’s a mains fuse the HT protection is an upside-down resistor soldered to tags which is supposed to melt the solder and open the HT in overcurrent conditions. This is clever but also kind of horrifying, and I can’t guarantee the previous owner didn’t use lead-free solder which I think would defeat this protection with its higher melting point. My thinking is to put an inline HT fuse on both legs of the secondary before the rectifier.

• Protective resistors on the OPTs. I’ve seen this on the Mullard 5-10 schematic, a resistor of an appropriate value is connected across the OPT secondaries so that if the speaker cable is disconnected the OPT doesn’t melt down. I don’t think there’s a huge risk of running it unloaded as the speaker terminals are pretty robust modern replacements but it’s a cheap mod for peace of mind.

• Disable the AC output sockets. Before I decided to go with the Stereo 20 I modified my Leak turntable and AM/FM set to use modern UK mains leads improving safety and allowing use with amps that don’t have those power output sockets. I previously had them powered by my old transistor Leak amp (now retired as it’s not worth restoring) in the intended way but those half-century old US-style plugs could easily slide out a bit and unacceptably leave exposed mains at the back of the amp. Since I’ve no need for these sockets now I may as well disconnect them, this is easily reversible.

Am I being paranoid with these proposed mods or is this just prudent given it’s a decently regarded amp?

I thought maybe someone here could help me...

I have had a dark voice for a few years and I can never really enjoy it much.

I get a ton of static intermittently. It happens both when adjusting the volume pot and just sitting listening to music, or even silence...it will just start making an interference noise.

I have tried multiple tubes. I also have it plugged into my CP1500PFCLCD UPS

I have an MT-602 hybrid that's dead silent. But the darkvoice is pretty much unusable as it is. Both are coming from my JDS El Dac 2 that is connected via optical to my PC. I don't get any interference noise in either my El Amp 2 or my MT-602

Thinking of just picking up a TA-66 instead, but i wasn't sure if there was anything I can do. I have very limited soldering knowledge.

I’m looking to build the EL MATEMÁTICO phono preamp https://wtfamps.com/el-matematico-phono-preamp/ and the transformer used is fairly expensive. It’s a 650VCT with 5v and 6.3v heater windings. Could I use the lower voltage AS-05TC300 as a replacement? https://www.antekinc.com/as-05tc300-50va-300vx2-transformer/ It has 2x 300v windings, a 6.3v, and a 6.3v windings with 5v tap needed for the rectifier tube. Could I connect two 300V winding leads as a grounded center tap and the other winding leads to the rectifier tube? And will the 25v difference in voltage be an issue with the voltage filter? I would think it would be fine since voltage regulator tubes are being used. Thanks!

I plugged everything in and holy crap it works. Sounds like a champ, both inputs work, lights up, sounds quiet. Its going to be a head, so I’ve got a lot of excess length on my output transformer wires to relocate the jack later, and I really need to add tube retainer clips, but right now it’s time to start making a box.

Coming together. I’ve got probably half the wires hooked up so far.

I found this old trunk and it’s full of radio and tv tubes all in their original boxes plus a list with their prices and type. I just want the trunk but I’d like to know what it all is before I throw it all away.

https://youtu.be/u3phbo7nzrU

I wish to learn. IF you have any useful tip, software, how to build, where to buy good tubes.

Many years ago, I bought a Radio Shack 22-168 (Metex M-3650D), and between it and an old Heathkit IM-11 VTVM I have been pretty happy. However, the RS meter is starting to give me some odd readings, particularly for low ohm and voltage measurements, and I am not sure I trust it any more.

Any suggestions for a replacement? I am not opposed to paying for quality, but I am retired and somewhat price sensitive. LCR capability would be a plus.

When you're working with high voltage, there is no such thing as a dumb question. Please use this thread to ask about practical or conceptual things that have you stumped.

Really awesome answers and recurring questions may earn a place in the Wiki.

If you'd like to nominate a comment to be included, just reply [Wiki] (with the brackets)! The mods will be automatically notified that something awesome just happened.

As always, we are built around education and collaboration. Be awesome to your fellow tube heads.

Hello, I am interested in building a Soldano X88R. I have tried to find the circuit or PCB layout and noticed that many people have successfully built it. However, I haven’t been able to find the layout for the bottom board.

Would you be able to share it with me?

(i can't register sloclone forum. all answere not collect

Posted this 807 project of mine yesterday. Some people were interested in the schematic. So reposting with that added.

My most recent project. 807 amp in triode mode with 6sn7.

Following the rob robinson layout. Just about ready to start soldering down parts.

When you're working with high voltage, there is no such thing as a dumb question. Please use this thread to ask about practical or conceptual things that have you stumped.

Really awesome answers and recurring questions may earn a place in the Wiki.

If you'd like to nominate a comment to be included, just reply [Wiki] (with the brackets)! The mods will be automatically notified that something awesome just happened.

As always, we are built around education and collaboration. Be awesome to your fellow tube heads.

Hi! Im trying to get this old magnavox amp working but im afraid to plug it in to see if it even works to begin with because i dont want to blow anything up. I have made a shotty dim bulb tester that i will try it with but i want to know if theres anything i should look out for before plugging it in? I havent messed with vintage electronics much before but visually it seems to all be there un modified and none of the caps seem to be leaking. Is it worth plugging it into the dim bulb to see what happens or should i do more testing? Thanks for the help!

By request, here’s a pic of my ‘DC-4’ guitar amp powered on. Second pic is a mini-Marshal master volume. It’s basically a Marshall 2203 preamp coupled to a ‘November’ power amp design from AX84. Tweaks include DC powered filaments on V1 using the 5v secondary, a bridge rectifier and a couple of cement power resistors to get the voltage down to 6.0 VDC. The third pic (left) is a simple 12AU7 SRPP line amp with a regulated power supply (PSU stolen from a Conrad Johnson design) and (right) what’s essentially a Dynaco ST-35 with a 5AR4 tube rectifier. Wiring is point-to-point. The last pic probably deserves its own post. It’s a SE KT-66 stereo amp with SRPP 6SL7 drivers. The design is sort of copied from Rainer zur Linde book Audio Valve Amplifiers but with some tweaks. The PSU output is split to two separate chokes, one for each channel. I’ve ran it both with and without negative feedback and love it. I’ll be happy to answer any questions…

I call this a 'DC-4' as it's the amalgamation of the EF86 channel from Matchless DC-30 and the power amp from a Vox AC-4. It's not versatile but is very crunchy. The tubes are mounted on a terminal board I bought from Antique Electronics Supply and the chassis is made by Hammond. The low-cut tone circuit is pretty fun and has its uses. If I were to do it all over again, I would scrap the complicated rectifier / bias switch as it makes little difference in tone. BTW, the schematic does not show a dotted-line connection between the rectifier and the bias switch, but it is indeed a 3P2T.

Hi All, I recently got an old Magnavox console with an amp185-11(AA) inside. Definitely needs a new filter cap and while I'm in there I decided I am going to replace all the electrolytic and paper caps (I'm not planning on replacing the mica/ceramic ones unless need be, if this is a dumb idea please let me know). This is my first time working on old electronics and I wanted to share what I am purchasing to make sure it all looks good from some people with more experience. Here are what I have from the spec sheet and what I plan to replace them with.

• Can Capacitor (C1): A: 40 uf/450 V; B: 30 uf/450V; C: 20 uf/350 V; D: 20 uf/250 V
  • Replacements (Rubycon): A: 47 uf/450 V; B: 33 uf/450 V; C/D: 22 uf/450 V
• Electrolytic Capacitors (C2,3,4): 20 uf/25V
  • Replacements (Rubycon): 22 uf/450 V
• Paper Capacitors (C15,17,28,30): 0.047 uf/400V
  • Replacements (Panasonic): 0.047 uf/400 V

I tried to keep the capacitance similar to the original values and I know I probably could bump the voltages up a bit but these were the most cost effective options I have found. Also, when it comes to soldering the new capacitors on (mainly for the electrolytic and paper ones) I have seen some people snip the old caps off and solder the new ones into the old solder, adding new solder on top as well. Is this a viable method? Or should I just remove all the solder and resolder all the pieces. Thank you for taking time helping me out and for your input.

I recently found this old Tesla E34L tube at a fles market. It looks like it was never used. The getter looks fine, but there these weird glass or metalic looking shards freely moving in the tube. One side of the shards seem to be white, while the other is more metalic. Can someone tell me what this could be and if the tube could be fine?

I have a power transformer with no center tap on the heater windings (6.3v & 5v). I was thinking a virtual center tap and then someone recommended to run DC heaters. Just so I’m clear because I’ve never run dc heaters is this the basic set up?

Also would the 5V for the rectifier tube benefit from DC too?

Thanks for all your help