I should probably explain a little bit as to why I had so many left over parts. The eight 1uF ceramic caps were all replaced with WIMA polyester 50V caps. The blue LED's were simply not installed. The four 2.2k resistors were not installed because they are part of the LED circuit branch and therefore not needed. The two D667 and two B647 transistors were not installed in the first kit that I built because I used a different B+ supply to drive that kit. The two 680uF 16V electrolytics were replaced with 470uF 35V electrolytics because I wanted a higher voltage rating for this capacitor. The two 1k, two 4.7K, and four 47 ohm resistors were not used on the first kit that I built because I used a different B+ supply on that kit. Hope this helps. Bill
They sent six 1n4007 diodes in the kit. Only room for five. Had me scratching me bum head looking for its seat. Yep, replaced most of the resistors with 1%Dale, caps with Wima and Rubycon, although Nichicon has a special 'music' electrolytic that is supposed to sound very good, and diodes via Vishay.
Mouser didn't have any 1/2watt 470k Dale cfm resistors so I ordered a 1/2watt Dale rn. Should have looked before ordering as it was about 4 times the size of the cfm. No way would it fit ... and I tried very hard to make it fit.
@Kornbread said:
They sent six 1n4007 diodes in the kit. Only room for five. Had me scratching me bum head looking for its seat. Yep, replaced most of the resistors with 1%Dale, caps with Wima and Rubycon, although Nichicon has a special 'music' electrolytic that is supposed to sound very good, and diodes via Vishay.
Mouser didn't have any 1/2watt 470k Dale cfm resistors so I ordered a 1/2watt Dale rn. Should have looked before ordering as it was about 4 times the size of the cfm. No way would it fit ... and I tried very hard to make it fit.
Looking good, Kornbread. Hope the parts work out OK.
@Kornbread said:
Has anyone checked to see if this thing outputs dc at turn-on?
Yes. On my 2nd build, the turn-on DC spike measured about 50mv and the turn-off DC spike measured about 100mv. This, however, was measured with my digital multi-meter, which may not be capturing the true value of these spikes. If you watch the StuffMade video that was posted by Tom at the beginning of this thread, the Stuff Made author measured the turn-on and turn-off dc spikes of his modified preamp and found a 500mv turn-on spike and a 1000mv turn-off spike. This can be found at the 29:15 time mark in the 31:47 minute long video. He advised turning on the preamp first, then after the spikes have occured, turn on your power amp.
I used some 4/40 aluminum standoffs on mine and countersunk the bottom screws. Mine were Male-Female threads, so I put the threads up on the board side and used nyloc nuts on top.
I used two of the green PCB boards. They came from the factory pre-drilled with metric M3 size mounting holes. M3 is half way between 4/40 and 6/32, so, as Tom indicated, 4/40 will work on the green boards also. I used 1/2" long threaded aluminum standoffs with 1/4" thick nylon spacers on mine. See pic. The nylon spacers are there to prevent the metal standoffs from shorting out nearby pcb traces and solder pads. Then I used 3/8" long machine screws on the top and bottom to sandwich it together. The screw heads stick out about 1/16" proud of the cabinet bottom, but I also have four rubber pads on the bottom of my cabinet, which provide enough clearance for the screws.
Listened to mine for a while today. First listen was wth??? This sux. Checked easy to reach components for good contact and fired it up again. Same. Pulled the included tubes and installed the Voskhod Rockets in and viola. The oem tubes were trash. Sound wise, it's ok. I'll have to listen for a while then drag out the old 4s Universal preamp for comparison. https://diy.midwestaudio.club/discussion/860/4s-universal-tube-pre/p1
Once I assemble mine I'm thinking to use it as the volume control for a 2.1 plate amp. Since those only have a volume control knob on the plate itself. Will be my PC setup. Any reason it would not work for this purpose? Only thing I could forsee is too much gain making the knob too sensitive.
You should be OK. Without any mods, the gain of the 6J1 amp is about 15 to 18dB or so. With the suggested mods, the closed loop gain drops into the 6 to 10dB range. I use mine with a small Lepai 2020 amplifier and I can play music up to clipping levels from my phone with the volume of the 6J1 and Lepai both set at about 1pm.
@Kornbread said:
Yep, replaced most of the resistors with 1%Dale, caps with Wima and Rubycon,
Mouser didn't have any 1/2watt 470k Dale cfm resistors so I ordered a 1/2watt Dale rn. Should have looked before ordering as it was about 4 times the size of the cfm. No way would it fit ... and I tried very hard to make it fit.
What wattage rating did you get your resisitors? I was probobly going to order name-brands from Mouser too, I was thinking 1/4 watts for everything except the big 2.2 ohm one?
1/2 watt Dale cmf 1%. Went Dale for the 2.2ohm RS02B2R200FE12. Make sure you check the physical size as the RN 1/2 watt Dales are way larger than the same rated cmf. Need a Mouser pick list?
Yep, they are. Guess shipping will be 'hit or miss'. I'll get them ordered.
Had a short comparo between the 6j1 vs 4sUniversal, that's no longer universal. Guess that makes it just a 4s? Anyhow, not much of a comparison. The 4s beats the pants off the 6j1 in pretty much every way, but I know how much difference a tube can make so we'll get some tube'eg on the way and start rolling, rowing ... swapping $hit around. Not too worried about the Wima output caps in the 6j1 holding the sound back as they sounded fine in the 4s.
All soldered up. I put on all the caps from mouser so should be ok for voltage using the higher VA rated power supply on the voltage doubler side. I tried swapping the 2.2ohm 2watt resistor for a 4ohm 5watt unit on the heater circuit. No smoke or pops but heater voltages read 6.5v and 6.3v. sooo?
I do have some "GE" tubes to play with too.
The suggested caps from mouser are slightly too tall for the acrylic case but should still fit since there should be enough screw thread to clamp the top down. I had to bump up the narrower cap due to the bigger resistor crowding it, so the case won't work for me right now. Though the bottom of it still works to isolate the underside.
I give it a trial run. Inserted it between my AT turn table with built-in preamp and my stereo receiver. Slapped on Dark Side of the Moon and let 'er rip.
Well. It makes sound. Heavily weighted to one channel and sounded pretty meh.
Being rather underwhelmed, I decided to chance the GE tubes. Holy cow what a transformation! Much more balanced L/R and that tooby holographic effect like I could reach out and grab whatever was making the sound. Those clock alarms....omg...
They cost as much as the kit, which is still pretty cheap. But you get way more than double the sound IMO. Definately worth it if you are springing for all the other "fixins" anyway.
Then I took it out of the signal path and listened again to compare. So with the tube preamp in-line you lose a bit of crispness, but gain that whole depth of soundstage. Like comparing the feeling of a nice form fitting stiff starched shirt to a warm bath that you feel the water swirling around as you move. Pick your poison. Probably mood dependant on which is most pleasing. But I noticed one nice side effect of that loss of crispness is it does neuter the majority of the subtle vinyl crackles.
Welcome to the club of the 2nd Harmonic. I'm glad to hear the 5654Ws are working better than the stock tubes. Yeah, tube gear is not something I want to run all the time, but there is something about a heated triode that makes you want to stay up and listen well past your bedtime.
I've witnessed similar effect from JR's LPS/Insomniac GRS 3-way. Hifiside tested the mid and it shows a good amount of HD2 while HD3 is still surpressed. I think that is what makes it sound so special. The tweeter and woofer don't have the HD2 so the speaker still sounds crisp and tight while the vocals and guitar are in the friggin room with you.
The 5watt resistor required some shoehorning at the bottom left. Though even with the different tubes the difference between voltage on the heaters is the same (6.5v, 6.3v). Measuring 12.9v across both so looks like the 4ohm isn't cutting it. This is all my own doing so nothing anyone else will need to deal with unless using a larger transformer.
I tried direct wiring the power switch to regain functionality after cutting and peeling up the traces with a box cutter. No hum on speakers that are north of 90db/2.83v/m
Comments
Do you need some, or because you got done and had some left over?
I ordered 2 of the green kits from California. After building both kits, here is a listing of my left over parts:
I should probably explain a little bit as to why I had so many left over parts. The eight 1uF ceramic caps were all replaced with WIMA polyester 50V caps. The blue LED's were simply not installed. The four 2.2k resistors were not installed because they are part of the LED circuit branch and therefore not needed. The two D667 and two B647 transistors were not installed in the first kit that I built because I used a different B+ supply to drive that kit. The two 680uF 16V electrolytics were replaced with 470uF 35V electrolytics because I wanted a higher voltage rating for this capacitor. The two 1k, two 4.7K, and four 47 ohm resistors were not used on the first kit that I built because I used a different B+ supply on that kit. Hope this helps. Bill
They sent six 1n4007 diodes in the kit. Only room for five. Had me scratching me bum head looking for its seat. Yep, replaced most of the resistors with 1%Dale, caps with Wima and Rubycon, although Nichicon has a special 'music' electrolytic that is supposed to sound very good, and diodes via Vishay.
Mouser didn't have any 1/2watt 470k Dale cfm resistors so I ordered a 1/2watt Dale rn. Should have looked before ordering as it was about 4 times the size of the cfm. No way would it fit ... and I tried very hard to make it fit.
Looking good, Kornbread. Hope the parts work out OK.
Has anyone checked to see if this thing outputs dc at turn-on?
Yes. On my 2nd build, the turn-on DC spike measured about 50mv and the turn-off DC spike measured about 100mv. This, however, was measured with my digital multi-meter, which may not be capturing the true value of these spikes. If you watch the StuffMade video that was posted by Tom at the beginning of this thread, the Stuff Made author measured the turn-on and turn-off dc spikes of his modified preamp and found a 500mv turn-on spike and a 1000mv turn-off spike. This can be found at the 29:15 time mark in the 31:47 minute long video. He advised turning on the preamp first, then after the spikes have occured, turn on your power amp.
Any recommendation on standoffs? Metal, nylon? Won't the screw heads poke through the bottom of a case?
I used some 4/40 aluminum standoffs on mine and countersunk the bottom screws. Mine were Male-Female threads, so I put the threads up on the board side and used nyloc nuts on top.
I used two of the green PCB boards. They came from the factory pre-drilled with metric M3 size mounting holes. M3 is half way between 4/40 and 6/32, so, as Tom indicated, 4/40 will work on the green boards also. I used 1/2" long threaded aluminum standoffs with 1/4" thick nylon spacers on mine. See pic. The nylon spacers are there to prevent the metal standoffs from shorting out nearby pcb traces and solder pads. Then I used 3/8" long machine screws on the top and bottom to sandwich it together. The screw heads stick out about 1/16" proud of the cabinet bottom, but I also have four rubber pads on the bottom of my cabinet, which provide enough clearance for the screws.
EDIT: Whoops, forgot to attach the pic:
Listened to mine for a while today. First listen was wth??? This sux. Checked easy to reach components for good contact and fired it up again. Same. Pulled the included tubes and installed the Voskhod Rockets in and viola. The oem tubes were trash. Sound wise, it's ok. I'll have to listen for a while then drag out the old 4s Universal preamp for comparison. https://diy.midwestaudio.club/discussion/860/4s-universal-tube-pre/p1
Once I assemble mine I'm thinking to use it as the volume control for a 2.1 plate amp. Since those only have a volume control knob on the plate itself. Will be my PC setup. Any reason it would not work for this purpose? Only thing I could forsee is too much gain making the knob too sensitive.
You should be OK. Without any mods, the gain of the 6J1 amp is about 15 to 18dB or so. With the suggested mods, the closed loop gain drops into the 6 to 10dB range. I use mine with a small Lepai 2020 amplifier and I can play music up to clipping levels from my phone with the volume of the 6J1 and Lepai both set at about 1pm.
I had mine hooked up to a chip amp (~60 watts/ch) and it seemed to have more than enough gain.
added - I did the same mods as Bill and had about the same gain.
What wattage rating did you get your resisitors? I was probobly going to order name-brands from Mouser too, I was thinking 1/4 watts for everything except the big 2.2 ohm one?
1/2 watt Dale cmf 1%. Went Dale for the 2.2ohm RS02B2R200FE12. Make sure you check the physical size as the RN 1/2 watt Dales are way larger than the same rated cmf. Need a Mouser pick list?
If I order a ten pack of 6j1 (6ak5) Voskhod w/otk stamp, anyone else want some? Shipping will be from Ukraine and probably a month.
If those are the ones from Radio Tubes Ukraine on eBay, I'm in for a pair or two!
Yep, they are. Guess shipping will be 'hit or miss'. I'll get them ordered.
Had a short comparo between the 6j1 vs 4sUniversal, that's no longer universal. Guess that makes it just a 4s? Anyhow, not much of a comparison. The 4s beats the pants off the 6j1 in pretty much every way, but I know how much difference a tube can make so we'll get some tube'eg on the way and start rolling, rowing ... swapping $hit around. Not too worried about the Wima output caps in the 6j1 holding the sound back as they sounded fine in the 4s.
Kornbread - I'm in for a pair!
Anyone else for a pair? Est. delivery date 03-29.
I'll take a pair
I'll take a pair, too.
Ordered 10pcs. Everybody should get a pair ... as long as they make it here.
All soldered up. I put on all the caps from mouser so should be ok for voltage using the higher VA rated power supply on the voltage doubler side. I tried swapping the 2.2ohm 2watt resistor for a 4ohm 5watt unit on the heater circuit. No smoke or pops but heater voltages read 6.5v and 6.3v. sooo?
I do have some "GE" tubes to play with too.
The suggested caps from mouser are slightly too tall for the acrylic case but should still fit since there should be enough screw thread to clamp the top down. I had to bump up the narrower cap due to the bigger resistor crowding it, so the case won't work for me right now. Though the bottom of it still works to isolate the underside.
I give it a trial run. Inserted it between my AT turn table with built-in preamp and my stereo receiver. Slapped on Dark Side of the Moon and let 'er rip.
Well. It makes sound. Heavily weighted to one channel and sounded pretty meh.
Being rather underwhelmed, I decided to chance the GE tubes. Holy cow what a transformation! Much more balanced L/R and that tooby holographic effect like I could reach out and grab whatever was making the sound. Those clock alarms....omg...
They cost as much as the kit, which is still pretty cheap. But you get way more than double the sound IMO. Definately worth it if you are springing for all the other "fixins" anyway.
https://amazon.com/dp/B088RBVVF3?psc=1&ref=ppx_yo2ov_dt_b_product_details
Then I took it out of the signal path and listened again to compare. So with the tube preamp in-line you lose a bit of crispness, but gain that whole depth of soundstage. Like comparing the feeling of a nice form fitting stiff starched shirt to a warm bath that you feel the water swirling around as you move. Pick your poison. Probably mood dependant on which is most pleasing. But I noticed one nice side effect of that loss of crispness is it does neuter the majority of the subtle vinyl crackles.
Harmonics?
Welcome to the club of the 2nd Harmonic. I'm glad to hear the 5654Ws are working better than the stock tubes. Yeah, tube gear is not something I want to run all the time, but there is something about a heated triode that makes you want to stay up and listen well past your bedtime.
I've witnessed similar effect from JR's LPS/Insomniac GRS 3-way. Hifiside tested the mid and it shows a good amount of HD2 while HD3 is still surpressed. I think that is what makes it sound so special. The tweeter and woofer don't have the HD2 so the speaker still sounds crisp and tight while the vocals and guitar are in the friggin room with you.
The 5watt resistor required some shoehorning at the bottom left. Though even with the different tubes the difference between voltage on the heaters is the same (6.5v, 6.3v). Measuring 12.9v across both so looks like the 4ohm isn't cutting it. This is all my own doing so nothing anyone else will need to deal with unless using a larger transformer.
I tried direct wiring the power switch to regain functionality after cutting and peeling up the traces with a box cutter. No hum on speakers that are north of 90db/2.83v/m