Thanks, can you please put some pic on how your connections are done. When you say large trace at the back of the Korg board I am not sure what you are referring to on the pcb board.
See on the photos at 9 o clock output is in low voltage range ~ 053 mV.
Potentiometer position at 12 o clock give 1.28 V at the output.
It's a work in progress.... preamplifier needs good quality chassis now.
Twisted wires or parallel doesn't make an audible difference, twisted are neat.
Salutations 🙂 Kind regards
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Yes Keithley do the electronic hobby job EEVblog #478 - Keithley 2015 THD Multimeter Teardown.
You right MEPER speakers are 98 dB and amplifier with gain of 20 dB and audio source DAC output are 2V.
Greetings 🙂
I am not finishing to learn how making accurate measurements
Measuring Distortion with a HP 339A and a Keithley 2015 THD
It seems to be still produced by Keithley so not easy to get it very cheap at ebay 🙂
But you never know…….maybe an auction where you are lucky…...
But you never know…….maybe an auction where you are lucky…...
The trace around the periphery of the board is the common ground point for input, output and power grounds. Post #1396 shows my wiring scheme. If I had placed an internal power supply within the case (either analog or switching) I would have shielded (coax or twisted) the inputs and connected the shield only at the input jacks.
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Just finished a diyaudiostore B1Korg kit. Running in now with ~ 9.6 V. Sounds quite good. Maybe a little bitt mellow as pre for my M2s. Need to adjust my ears, just came from a passive relay volume pre. Lots of detail and heft, no aggressiveness. Great pre 🙂
Some ringing when turning on and switching source, how erwer my altecs seem not to excite the korg. Runnig through a 230-110 trafo as I dont have a 110-230 adaptor for the std external powersupply.
Some ringing when turning on and switching source, how erwer my altecs seem not to excite the korg. Runnig through a 230-110 trafo as I dont have a 110-230 adaptor for the std external powersupply.
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Congratulations Kbergsson!
Do reverse polaritys of the speakers make B1Triode phase effect on Your Voices of the Theatre ?
Do reverse polaritys of the speakers make B1Triode phase effect on Your Voices of the Theatre ?
Thanks Soundhappy. Well triode phase effect, Im not sure, they have a lot of detail but still a smooth and rich sound signature. 3d is good, as far as the Altecs can conwey 3d. They dont however turn my M2 into a 300b amp. I have 300b, pentode driven, monoblocks to compare. Need to try them with other amps. Espesially a rather harsh and overcontrolling class D amp.
Lots on EBAY but no cheap ones since Dave on EEV blog did the teardown!!
There's an EEV Forum recommendation for this multifunction USB type with signal generator, oscilloscope etc all rolled into one instead that gets some good reviews:
Analog Discovery 2 Pro Bundle - Digilent
I'm tempted but no spare money at the moment.
I also think I will use my FocusRite and PC software for THD measurement. 6,5 digit multimeter is very tempting…..but again…..when do I need that precision?
I have seen them down to about 500 Euro's on ebay but some are 3500 Euro's. If you get a very old one….20 years old or so....you never know…..it may be a bit out of spec….
I have seen them down to about 500 Euro's on ebay but some are 3500 Euro's. If you get a very old one….20 years old or so....you never know…..it may be a bit out of spec….
Thank you now I got it. I used one of the mounting legs as ground point in mine and used nylon legs to isolate the legs from the chassis mounting. But I think I may need to revisit my wiring after looking into yours as I get hum with a LDR based source and volume control all in one board.
B1 Korg Just Got Better
I finally got around to swapping in the Tocos Cosmos 50kohm volume pot, and a pair of .22uF NOS Panasonic ECQP Polypropylene film and foil caps, and a pair of 1uF Radio Shack (i.e., Xicon) MKT film caps on the inputs.
I haven’t replaced the output caps yet, but those will be next. I have a pair of unobtainium 4.7uF NOS Black Gate N non-polar electrolytic capacitors that I have been hanging onto. I first wanted to see what improvements the Tocos Cosmos volume pot and film caps on the inputs would make. Well, these tweaks suggested by ClaudeG have made a great preamp even better. It sounds like a veil has been removed from the music. The preamp has a greater sense of presence and a larger scale. The soundstage has definitely improved and the definition of low level details is more audible. The separation between performers is better defined as well. These tweaks really take this preamp to another level.
The richness of tone and smoothness of the B1 Korg has been retained, but the frequency extremes are more apparent, which might contribute to the higher definition. My wife explained that my system sounded “clearer” and “fuller.”
Thanks ClaudeG for the recommendations. I highly recommend to anyone else with a B1 Korg to consider them. My KEF LS50’s just disappear and I am immersed in the music. For my taste, I have both T7 and T8 set at 10.5 VDC.
I finally got around to swapping in the Tocos Cosmos 50kohm volume pot, and a pair of .22uF NOS Panasonic ECQP Polypropylene film and foil caps, and a pair of 1uF Radio Shack (i.e., Xicon) MKT film caps on the inputs.
I haven’t replaced the output caps yet, but those will be next. I have a pair of unobtainium 4.7uF NOS Black Gate N non-polar electrolytic capacitors that I have been hanging onto. I first wanted to see what improvements the Tocos Cosmos volume pot and film caps on the inputs would make. Well, these tweaks suggested by ClaudeG have made a great preamp even better. It sounds like a veil has been removed from the music. The preamp has a greater sense of presence and a larger scale. The soundstage has definitely improved and the definition of low level details is more audible. The separation between performers is better defined as well. These tweaks really take this preamp to another level.
The richness of tone and smoothness of the B1 Korg has been retained, but the frequency extremes are more apparent, which might contribute to the higher definition. My wife explained that my system sounded “clearer” and “fuller.”
Thanks ClaudeG for the recommendations. I highly recommend to anyone else with a B1 Korg to consider them. My KEF LS50’s just disappear and I am immersed in the music. For my taste, I have both T7 and T8 set at 10.5 VDC.
Thanks Rhing and ClaudeG
I have 3.3uF MKP on bench to try them at the inputs this evening 🙂 Greetings
Blackgate's now there is a unique mod, not many will be able to achieve.
Looking forward to the feedback.
Are they new unused or got a burn in time on them ?
Looking forward to the feedback.
Are they new unused or got a burn in time on them ?
Thanks guys 
In my case, just a minor and deserved contribution to a fabulous gift and adventure by Papa & Jim...
Enjoy tweaking
Claude
In my case, just a minor and deserved contribution to a fabulous gift and adventure by Papa & Jim...
Enjoy tweaking
Claude
New and unused stock. Bought them several years ago from Sonic Craft before their stock ran dry. I may just leave it in its current form, because it’s sounding fantastic. But you know, we just can’t leave anything alone. 🙂
At least wait until it is sounding merely good, and then try it 🙂 You shouldn't change a thing if it sounding fantastic!
I am noticing after a few days of listening that my L/R balance is beginning to skew to the left. I checked the L/R resistance of the volume pot across several points and they match within .01 ohms. The output voltage is different between L/R however. When L is exactly 1v the right is .95, lower in volume when L is .5v the right is .4 volts. This is tested using a 50hz sine wave test track. Where do I look next to find what is causing this issue? Happens across all source inputs. I did use all 1% resisters but perhaps one is drifting or has a bad solder joint.