I was surprised to find that several of my factory amps inverted signal polarity, a Cambridge Audio integrated amp and a less expensive tube-hybrid unit. An easy way to check that includes the loudspeakers is with a smart phone polarity checker "pulse" or "clicker" app connected to a line input.
When building new power amps, I typically use a dual trace oscilloscope and sine wave generator, comparing input to output, taking care to use an isolation transformer on the output of bridged output power amplifiers. But then I'm looking for possible oscillation and other bad behavior at the same time.
When building new power amps, I typically use a dual trace oscilloscope and sine wave generator, comparing input to output, taking care to use an isolation transformer on the output of bridged output power amplifiers. But then I'm looking for possible oscillation and other bad behavior at the same time.
I am curious: How far off the 24 volt supply value would the voltage have to be to start noticeably affecting the distortion signature? (Noticeable in that one would hear the difference, not see it in a measurement.)
Thanks,
Alan
Try the experiment yourself and find out! Just hook up a variable power supply and a voltmeter to the +24V connection, dial the voltage up/down, and listen. Thanks to the gigantic amount of noise filtering in the circuit (see schematic in post #1), the variable PSU can't degrade the pristine voltage rails at the active circuitry, so you don't have to worry about that detail at all.
Hello dear Diy community,
started with B1 Korg.
I finished Pearl Two, B1, F5 a couple of years ago, I would like "a little hotter".
And I notice that PCB from Diyaudio Store and Schematic from Papa are slightly different.
Haoffe it is not bad.
If this was a topic I would like a link for.
Thank you.
By the way, J113 from Faichild and ON Semiconduktor also have different topologies.
started with B1 Korg.
I finished Pearl Two, B1, F5 a couple of years ago, I would like "a little hotter".
And I notice that PCB from Diyaudio Store and Schematic from Papa are slightly different.
Haoffe it is not bad.
If this was a topic I would like a link for.
Thank you.
By the way, J113 from Faichild and ON Semiconduktor also have different topologies.
Smooth
I just finished the B1K, and it sounds great. A standard build with standard Nichicon caps, from the BOM, AMB A11 PSU with a toroid, all neat in the same box.
At first turn on I got a smooth, creamy, sound with piano sounding very realistic and accurate. Although I''m mostly a pop-rock person that just happened to be what the FM was playing at the time and I like what I'm hearing.
The B1K is going to a Akitika G102 diy power amp and to a fairly old pair of 1990's refurbished JBL's, I set the B1K bias at the recommended, default of 9.5v and I decided if it ain't broke it don't need fix'in. Later on, I did try changing the speaker cable to invert the phase, and maybe the mid-range came forward just a bit.
I always like to read a diy projects forum before a build. There is usually lots of hints and sometimes fixes. After toiling through the 500 plus pages of B1K posts, the most common issue seemed to be a howling sound. So here is my two cents worth on what I did to aleviate that issue.
Initially I didn't hear the problem, or at least not at first. There is some house building work going on next door to me and one day I decided to turn it up to drown out the noise. That was when I heard the high pitched whistle. I had taken measures during the build and had used some velcro tape and foam then double sided tape under the Nutube creating a kind of foam sandwich between a half centimetre of dense foam camping mattress. (see photos)
In the end, I don't think this made a whole lot of difference. I also took a turntable suspension type of idea and created some squidgy rings from small diameter sealant that came with some metal construction boxes. I think it was to seal against moisture, (See the photos).
I put one on the bottom of each of the four mounting screws of the circuit board and one on top as well, giving the board a kind of suspension. It worked well, until one evening when for no reason I could figure it started to scream all by itself.
I loosened the boards mounting screws, but this made things worse. So I tightened them a little instead and this fixed it. No, more howling even at high volumes. (Hope I'm not sounding too medieval here?) I don't normally listen to high levels, most of the time it's medium to low.
Maybe this suspension idea might help someone else who is still struggling. The stuff looks like spaghetti, some type of foam coated with a kind of rubbery skin. At the moment the box is still waiting on a lid to be made. Having no acoustic isolation doesn't seem to affect the Nutube though, so it might be more of a surface vibration feedback issue.
I just finished the B1K, and it sounds great. A standard build with standard Nichicon caps, from the BOM, AMB A11 PSU with a toroid, all neat in the same box.
At first turn on I got a smooth, creamy, sound with piano sounding very realistic and accurate. Although I''m mostly a pop-rock person that just happened to be what the FM was playing at the time and I like what I'm hearing.
The B1K is going to a Akitika G102 diy power amp and to a fairly old pair of 1990's refurbished JBL's, I set the B1K bias at the recommended, default of 9.5v and I decided if it ain't broke it don't need fix'in. Later on, I did try changing the speaker cable to invert the phase, and maybe the mid-range came forward just a bit.
I always like to read a diy projects forum before a build. There is usually lots of hints and sometimes fixes. After toiling through the 500 plus pages of B1K posts, the most common issue seemed to be a howling sound. So here is my two cents worth on what I did to aleviate that issue.
Initially I didn't hear the problem, or at least not at first. There is some house building work going on next door to me and one day I decided to turn it up to drown out the noise. That was when I heard the high pitched whistle. I had taken measures during the build and had used some velcro tape and foam then double sided tape under the Nutube creating a kind of foam sandwich between a half centimetre of dense foam camping mattress. (see photos)
In the end, I don't think this made a whole lot of difference. I also took a turntable suspension type of idea and created some squidgy rings from small diameter sealant that came with some metal construction boxes. I think it was to seal against moisture, (See the photos).
I put one on the bottom of each of the four mounting screws of the circuit board and one on top as well, giving the board a kind of suspension. It worked well, until one evening when for no reason I could figure it started to scream all by itself.
I loosened the boards mounting screws, but this made things worse. So I tightened them a little instead and this fixed it. No, more howling even at high volumes. (Hope I'm not sounding too medieval here?) I don't normally listen to high levels, most of the time it's medium to low.
Maybe this suspension idea might help someone else who is still struggling. The stuff looks like spaghetti, some type of foam coated with a kind of rubbery skin. At the moment the box is still waiting on a lid to be made. Having no acoustic isolation doesn't seem to affect the Nutube though, so it might be more of a surface vibration feedback issue.
- Hello, I have a question, I didn't see this idea as I read through the thread, but it's long and I could have missed it..... so has anyone modded their B1K so that the second order harmonics can be adjusted with a knob on the front panel ?
- My thought is as I use different tube, and solid state amplifiers with the B1k, as well as different speakers with the B1k , It might be helpful in matching the different amplifiers/speakers if it were easy to adjust from the front plate of the preamplifier...
- If not could someone show me how to do that?
Thanks for any help!
- My thought is as I use different tube, and solid state amplifiers with the B1k, as well as different speakers with the B1k , It might be helpful in matching the different amplifiers/speakers if it were easy to adjust from the front plate of the preamplifier...
- If not could someone show me how to do that?
Thanks for any help!
to hallcon83 #5248
You can also check my post #2138. There you can see it on the pics how I did it.
One possibility....
Greets
Dirk
You can also check my post #2138. There you can see it on the pics how I did it.
One possibility....
Greets
Dirk
Tweakers Heaven
A tweakers heaven - solves the two channel variable adjustment issue with one control - nice!
A tweakers heaven - solves the two channel variable adjustment issue with one control - nice!
- Hi Yoshida, thank you for your response! That looks like what I am looking to do - I'm new to building diy audio equipment .. Could you do a little drawing or schematic of how to wire that up correctly?
Best regards, Dean
Best regards, Dean
Thank you for comment.
Attached is a diagram explaining the wiring.
There are two pots on the figure, please do the same for the remaining four.
I haven't tested it yet, but depending on the type of switch (Break before Make), there may be noise when switching.
Please check carefully before connecting expensive equipment.
Its safe to switch only when the amplifier is powered off.
Attached is a diagram explaining the wiring.
There are two pots on the figure, please do the same for the remaining four.
I haven't tested it yet, but depending on the type of switch (Break before Make), there may be noise when switching.
Please check carefully before connecting expensive equipment.
Its safe to switch only when the amplifier is powered off.
Attachments
Since the kit is out of stock I'm trying to get all the parts individually. Anyone know what volume pot is used with this? Or a good one to use?
The B1K build guide, produced by 6L6, is now up:
B1 with Korg Nutube - diyAudio Guides
Many thanks to 6L6 for his typically wonderful work on this!
B1 with Korg Nutube - diyAudio Guides
Many thanks to 6L6 for his typically wonderful work on this!