Purchased the "Jonokuchi" PCB
Just completed the first step and purchased the "Jonokuchi" PCB from eBay, Thinking about using VISHAY-RODERSTEIN MKP-1837 Metalized Polypropylene
Film Capacitors in place of the WIMA MKS2 1.0/100/10 for C1 and C2.
Also Obbligato Gold Premium Capacitors and some other possible replacements for Wima MKP4-0.1/630/5PCM15 - C5 and C6
Just completed the first step and purchased the "Jonokuchi" PCB from eBay, Thinking about using VISHAY-RODERSTEIN MKP-1837 Metalized Polypropylene
Film Capacitors in place of the WIMA MKS2 1.0/100/10 for C1 and C2.
Also Obbligato Gold Premium Capacitors and some other possible replacements for Wima MKP4-0.1/630/5PCM15 - C5 and C6
Just deciding if I want to jump in & build this amp. Was wondering if the hum issue was ever completely solved. If it is indeed caused by the proximity of the power stormer, I wouldn't be opposed to housing it in a separate enclosure sitting on the floor. I would also be building this amp with point to point wiring, so any input on that is appreciated. If I go p2p & separate power xformer how close can I place the output xformers a to each other?
Thanks,
Kev
Thanks,
Kev
Kev, if you don't mind a separate enclosure for the power supply, that will surely solve the problem. I'd put the power transformer, rectifier, and filter caps in the remote box.
I have had a couple of reports that either moving the transformers, or shielding them with mumetal cans, cures the hum issue. Unfortunately I don't know exactly how far they moved the transformers - I think no more than an inch or maybe two. When I chose the chassis size I pretty much moved them apart until I didn't hear any hum, so that's how they wound up where they are now.
You do have to consider that different people have different sensitivities to hum, and also the type of headphones used makes a big difference.
I use mine (normal PCB build) every day as a speaker amp, and I cannot hear any hum from the speakers. With high-Z headphones (like HD6750s) I also cannot hear any hum. With Grados I can hear some hum, but it doesn't bother me. But then again, I don't normally listen to Grados
Pete
Kev, if you don't mind a separate enclosure for the power supply, that will surely solve the problem. I'd put the power transformer, rectifier, and filter caps in the remote box.
I have had a couple of reports that either moving the transformers, or shielding them with mumetal cans, cures the hum issue. Unfortunately I don't know exactly how far they moved the transformers - I think no more than an inch or maybe two. When I chose the chassis size I pretty much moved them apart until I didn't hear any hum, so that's how they wound up where they are now.
You do have to consider that different people have different sensitivities to hum, and also the type of headphones used makes a big difference.
I use mine (normal PCB build) every day as a speaker amp, and I cannot hear any hum from the speakers. With high-Z headphones (like HD6750s) I also cannot hear any hum. With Grados I can hear some hum, but it doesn't bother me. But then again, I don't normally listen to Grados
Pete
Thanks Pete,
I think I will go with the separate enclosure, as I like that Idea anyway. In the interest of making the amp enclosure as small as is practical, do you have a minimum separation of the output transformers, or do they not interact audibly? I am building it with p-p wiring, so I am just starting to work on cabinet designs.
Thanks,
kev
P.S. I have headphones from 32 - 600 ohms, but am currently favoring some with 50 ohm imp.
Almost there, But not quite
After starting this project almost two months....with waiting and deciding on parts, The board has been finished for a few weeks now.
The three EDCOR transformers will arrive next week after a little over a month of waiting.
I decided to go with the Jensen 0.22uf/630V pure copper foil / paper in oil (eBay) for the two coupling capacitors (C5 & C6) ....also decided to go with the Hammond 157J filter choke in place of (R5) 220 Ohm 5W
I still need a chassis, I've tried drilling two now by hand but using a drill press would make it so much better and easier. I think the almost $300 that Front Panel Express charges for the ready to go chassis is outrageous but unless you know someone with a machine shop you're pretty much backed into a corner.
I'm really looking forward to firing up my first tube amp build for the first time, But the whole chassis problem may cause a even longer delay.
After starting this project almost two months....with waiting and deciding on parts, The board has been finished for a few weeks now.
The three EDCOR transformers will arrive next week after a little over a month of waiting.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I decided to go with the Jensen 0.22uf/630V pure copper foil / paper in oil (eBay) for the two coupling capacitors (C5 & C6) ....also decided to go with the Hammond 157J filter choke in place of (R5) 220 Ohm 5W
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I still need a chassis, I've tried drilling two now by hand but using a drill press would make it so much better and easier. I think the almost $300 that Front Panel Express charges for the ready to go chassis is outrageous but unless you know someone with a machine shop you're pretty much backed into a corner.
I'm really looking forward to firing up my first tube amp build for the first time, But the whole chassis problem may cause a even longer delay.
The interaction between the two OPTs is pretty insignificant. I would put 2" between them, that should be plenty.
Pete
Slight buzz from middle pot position.
Hi Guys,
The Jonokuchi is my first build and I just completed it today. I had two issues right off the bat.
1. A buzz that was audible between 25% and 75% of the pot range of motion.
2. The slight hum.
To fix the buzz I shorted JP1 as recommended on Zynsonix's blog. This worked!
To fix the hum I used the mod on Pete's site by cutting the switch pins and adding 220 ohm resistors.
Now the hum is gone, but the buzz is back!! Any ideas?
Also, re: the hum mod, In the picture on Pete's site R21, R22, and R23 are all removed. Is this correct? I was under the impression that only R22 and R23 should be removed.
Thanks!
Hi Guys,
The Jonokuchi is my first build and I just completed it today. I had two issues right off the bat.
1. A buzz that was audible between 25% and 75% of the pot range of motion.
2. The slight hum.
To fix the buzz I shorted JP1 as recommended on Zynsonix's blog. This worked!
To fix the hum I used the mod on Pete's site by cutting the switch pins and adding 220 ohm resistors.
Now the hum is gone, but the buzz is back!! Any ideas?
Also, re: the hum mod, In the picture on Pete's site R21, R22, and R23 are all removed. Is this correct? I was under the impression that only R22 and R23 should be removed.
Thanks!
I just finished by first Jonokuchi as well and am having the same problems.
I haven't done the hum mod yet (220ohm resistor) but I am getting the same buzz from 25-75% volume. Any ideas??
If you are getting noise when the volume control is in the middle... quite often the issue can be solved by making sure that the metal bushing of the volume control is grounded. Sometimes the anodizing on the chassis prevents a good electrical contact between it and ground.
So, in addition to shorting JP1, try and temporarily connect ground and the bushing of the volume control pot with a wire or clip lead. If the noise goes away, then you can find a permanent way to ground it. It is possible to solder to the (zinc?) frame of the Alps pot, if you scrape it a bit with a knife and use some flux. Or you could use a big solder lug on the bushing, or even wrap some wire around the bushing before you tighten the nut.
Pete
So, in addition to shorting JP1, try and temporarily connect ground and the bushing of the volume control pot with a wire or clip lead. If the noise goes away, then you can find a permanent way to ground it. It is possible to solder to the (zinc?) frame of the Alps pot, if you scrape it a bit with a knife and use some flux. Or you could use a big solder lug on the bushing, or even wrap some wire around the bushing before you tighten the nut.
Pete
Thanks Pete!
I realized I never added the AC ground lead, that solved most of the buzz. The remainder was gone with the addition of JP1.
I added 330ohm resistors (didn't have any 220 ohm) as per the "hum mod" and did not remove R22 or 23. The output is dead quiet in the fairly expensive earbuds I am borrowing (Shure SE535) with plenty of output. I need to bring my Grados home from work to give them a try, but otherwise I am extremely pleased with the amp.
I realized I never added the AC ground lead, that solved most of the buzz. The remainder was gone with the addition of JP1.
I added 330ohm resistors (didn't have any 220 ohm) as per the "hum mod" and did not remove R22 or 23. The output is dead quiet in the fairly expensive earbuds I am borrowing (Shure SE535) with plenty of output. I need to bring my Grados home from work to give them a try, but otherwise I am extremely pleased with the amp.
Great thread.
Just collecting the parts for a Jonokuchi build and have a few preliminary questions:
(1) what output transformers would be suitable to give more output for some 90dB speakers? Edcor have a few different options on their site, but I don't have the technical knowledge to pick the correct one.
(2) can anything be done to reduce the measured 1.3% distortion in speaker mode? This seems rather high...
Just collecting the parts for a Jonokuchi build and have a few preliminary questions:
(1) what output transformers would be suitable to give more output for some 90dB speakers? Edcor have a few different options on their site, but I don't have the technical knowledge to pick the correct one.
(2) can anything be done to reduce the measured 1.3% distortion in speaker mode? This seems rather high...
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Further to the above post, I notice on the Jonokuchi website that Pete mentions "The OPT is an off-the-shelf 8k:8 ohm SE transformer from Edcor (GXSE10-8-8k). 8k is a higher load than most people use for a 13EM7 (6EM7) amplifier... I did this to get the distortion and Zout low. This is part of optimizing the amp for headphones and not speakers; if you needed more gain and more output power, you could use a lower impedance transformer, like 5k or even 3.5k."
So in terms of more powerful transformers to maximise speaker output, how would the GXSE10-8-8k best be replaced out of the following:
So in terms of more powerful transformers to maximise speaker output, how would the GXSE10-8-8k best be replaced out of the following:
Hey Guys,
Sorry for creating a duplicate post that I made on Head Fi, just thinking I might receive more responses here than there. So I apologize in advance.
Thank you Mr. Millett for creating such wonderful projects for us do to. Just bought all the parts, and I guess the transformers will arrive in 6-8 weeks. So excited, this is my first DIY project. I have a Computer Engineering degree, but nowhere close to that of a EE, so just a bit nervous about the high voltage. If you guys don't mind, I have a few questions:
1. What gauge of wiring should be used for the speaker binding posts to the PCB, along with the RCAs?
2. I see that HighFlying9 added a pilot light to the project. If I wished to add an LED, perhaps with an inline resistor to ground, where should I connect LED in terms of power to? It's been a while since I did some EE, software engineering is a bit easier, hehe. Using this as a reference: power supply - Add on/off indicator LED to circuit - Electrical Engineering Stack Exchange
Please let me know if there is an easier solution.
3. It looks like both the 1/4" and 1/8" jacks can be placed on the board. I have the Sennheiser HD 650 and a BeyerDynamic DT 990 250 ohm. That's a combined impedance of roughly 550 ohms. Would the amp be able to drive both sets of headphones at once, one placed on the 1/4" and another on the 1/8"?
4. I also have a set of Behringer Audio Truth 3030A (active studio near field monitors), which I connect using a direct input box (input is RCA, output is balanced XLRs to the speakers). Will I have any issues if I use the output of the 1/4" or the 1/8" to RCA to send the signal to the direct input box? Just curious as to your take on it.
5. It seems that spacing the OPTs by 2 or more inches away from each other helps the hum. I am thinking of going with acrylic as an enclosure, instead of a metal one. Will I have issues with the POT humming with acrylic, or any other issues?
Sorry if I have really dumb questions, just trying to learn a bit. Thanks for the help.
Sorry for creating a duplicate post that I made on Head Fi, just thinking I might receive more responses here than there. So I apologize in advance.
Thank you Mr. Millett for creating such wonderful projects for us do to. Just bought all the parts, and I guess the transformers will arrive in 6-8 weeks. So excited, this is my first DIY project. I have a Computer Engineering degree, but nowhere close to that of a EE, so just a bit nervous about the high voltage. If you guys don't mind, I have a few questions:
1. What gauge of wiring should be used for the speaker binding posts to the PCB, along with the RCAs?
2. I see that HighFlying9 added a pilot light to the project. If I wished to add an LED, perhaps with an inline resistor to ground, where should I connect LED in terms of power to? It's been a while since I did some EE, software engineering is a bit easier, hehe. Using this as a reference: power supply - Add on/off indicator LED to circuit - Electrical Engineering Stack Exchange
Please let me know if there is an easier solution.
3. It looks like both the 1/4" and 1/8" jacks can be placed on the board. I have the Sennheiser HD 650 and a BeyerDynamic DT 990 250 ohm. That's a combined impedance of roughly 550 ohms. Would the amp be able to drive both sets of headphones at once, one placed on the 1/4" and another on the 1/8"?
4. I also have a set of Behringer Audio Truth 3030A (active studio near field monitors), which I connect using a direct input box (input is RCA, output is balanced XLRs to the speakers). Will I have any issues if I use the output of the 1/4" or the 1/8" to RCA to send the signal to the direct input box? Just curious as to your take on it.
5. It seems that spacing the OPTs by 2 or more inches away from each other helps the hum. I am thinking of going with acrylic as an enclosure, instead of a metal one. Will I have issues with the POT humming with acrylic, or any other issues?
Sorry if I have really dumb questions, just trying to learn a bit. Thanks for the help.
1. It doesn't matter significantly, I'd use between 24AWG and 18AWG. It's only a couple of watts.
2. There's no low-voltage DC available, but you could use the filament supply (12VAC). Connect a diode (1N4148 or 1N4001 or similar) in parallel with the LED, but in reverse. Then use a resistor in series (4.7k should be fine) and connect to the two yellow filament winding wires. Like this: http://cdn.instructables.com/FKX/WTKS/GXVNI5KG/FKXWTKSGXVNI5KG.MEDIUM.jpg
3. Yes, it can drive both at the same time, no problem.
4. You can connect the powered monitors to the output, but you may have pretty high gain. You may wind up with the volume control most of the way down. And you may get a little noise because of that.
5. I think a plastic case will be OK, but you may have to run a grounding wire from the pot bushing to signal ground.
Pete
2. There's no low-voltage DC available, but you could use the filament supply (12VAC). Connect a diode (1N4148 or 1N4001 or similar) in parallel with the LED, but in reverse. Then use a resistor in series (4.7k should be fine) and connect to the two yellow filament winding wires. Like this: http://cdn.instructables.com/FKX/WTKS/GXVNI5KG/FKXWTKSGXVNI5KG.MEDIUM.jpg
3. Yes, it can drive both at the same time, no problem.
4. You can connect the powered monitors to the output, but you may have pretty high gain. You may wind up with the volume control most of the way down. And you may get a little noise because of that.
5. I think a plastic case will be OK, but you may have to run a grounding wire from the pot bushing to signal ground.
Pete
That sounds fantastic! Please do post pics so I can steal some of your ideas and use as my own!
Did you have any issues with buzzing or humming? Did you space apart the output transformers? Do the resistor fix? Experienced any other problems?
Hey Guys, Finally finished putting the amp together this weekend, after all the parts arrived. I am, however, having some issues. I would appreciate any suggestions for debugging the following issue: I have very little sound output from the left channel. It does not matter if I use 1/8" front or the rca rear inputs. It also does not matter if I use the 1/8" or the 1/4" outputs. Perhaps a bad ground? Also, when I slightly move the amp or the pot, I get static on the left channel as well. With a little bit of moving the amp, the static goes away. Everything seems to be left channel related. I don't have passive speakers to test the speakers output, so this is strictly a headphone out issue so far. Please let me know what I can debug, would greatly appreciate any help.
Update #1:
I originally thought the issue was with my 1/8" output jack and so I de-soldered it and replaced it with a new one. Now, not only do I have the same issues as before (can't really hear left channel), there is also a loud buzzing on the right channel. The buzzing gets louder as I increase the volume. I inspected all the solder joints to make sure there was enough solder and there weren't any solder bridges. Checked for continuity with my DMM. I guess I'll just try to resolder the shifty looking joints tomorrow.
I originally thought the issue was with my 1/8" output jack and so I de-soldered it and replaced it with a new one. Now, not only do I have the same issues as before (can't really hear left channel), there is also a loud buzzing on the right channel. The buzzing gets louder as I increase the volume. I inspected all the solder joints to make sure there was enough solder and there weren't any solder bridges. Checked for continuity with my DMM. I guess I'll just try to resolder the shifty looking joints tomorrow.
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