As I await arrival of my B1 Kong kit, I want to start planning an amp to pair with it. I will be driving Magnepan MMGWs and a sub. It’s a living room setup, and the little Maggie’s hang on the walls and just blend in and sound great, so they’re staying. A friend uses First Watt 25-watt monoblocks (I forget the model) with his MMGWs, and it’s enough power in his somewhat larger room. A single chassis would be preferable for me, to minimize the footprint, but I’m flexible, except I’m pretty committed to Class A or AB for this. So if anyone has suggestions for DIY amps, preferably Pass designs,I’d appreciate it. Thanks as always.
Regarding Pass designs, I think the M2(X) or F6 would do well into the 5 ohm load of your speakers. I've built both and prefer the sound of the M2. The Aleph J is another great sounding one, but the power output would be reduced into 5 ohms.
to jfuquay #5562
Hello Jfuquay,
the Magnepan magnetostats are very nice loudspeakers. Their sensitivity is at around 88dB /2.83V - so not really high.
Those are dipol - loudspeakers and they have to be 'adjusted' very well. This means you will need some time to find the right distance to the walls of the room and the angle to your listening position. They shouldn't be too close to a wall.
The Magnepan MMG W are pretty small for Magnetostats. So you will need an subwoofer to hear real bass (there will not be too much below 100 Hz)..
I agree with Batty and the others, that the M2-X combined with the B1-NUTUBE (preamp) will be a combination where you can play around so much, that you will find a very nice, ear-pleasing sound.
I have ESLs (Audiostatic ES300R) which are in a way similar to the Magnepans. My ESLs have a sensitivity of 89dB /1W/1meter). They are 4 Ohm. I drive them normally with my F5-T monoblocks. But also tried the
M2-X on them with excellent results.
I use a subwoofer with an x-over frequency of 80Hz. My ESLs don't like
low frequencies at higher levels.
If you buy them new - it will need minmum 100 hours of playtime, till they really come 'alive'. My experiences.
Greets
Dirk
Hello Jfuquay,
the Magnepan magnetostats are very nice loudspeakers. Their sensitivity is at around 88dB /2.83V - so not really high.
Those are dipol - loudspeakers and they have to be 'adjusted' very well. This means you will need some time to find the right distance to the walls of the room and the angle to your listening position. They shouldn't be too close to a wall.
The Magnepan MMG W are pretty small for Magnetostats. So you will need an subwoofer to hear real bass (there will not be too much below 100 Hz)..
I agree with Batty and the others, that the M2-X combined with the B1-NUTUBE (preamp) will be a combination where you can play around so much, that you will find a very nice, ear-pleasing sound.
I have ESLs (Audiostatic ES300R) which are in a way similar to the Magnepans. My ESLs have a sensitivity of 89dB /1W/1meter). They are 4 Ohm. I drive them normally with my F5-T monoblocks. But also tried the
M2-X on them with excellent results.
I use a subwoofer with an x-over frequency of 80Hz. My ESLs don't like
low frequencies at higher levels.
If you buy them new - it will need minmum 100 hours of playtime, till they really come 'alive'. My experiences.
Greets
Dirk
Fortunately, I’m just about all acoustic in my tastes. I also have the .7s in my listening room (Rogue Sphinx v2) and don’t even use a sub with them. With the MMGWs I use a nice tight little Martin Logan sub to fill out the sound. My brother, whose preferred style is the Stones and who wants a punch in the gut when he listens, prefers the MMGWs + sub combo, even though the amp is just a little Class D with 40-ish watts into 5-ohm speakers. To each his own.
Korg B1
Hi,
New to this, so not sure where to ask these questions.
Sorry in advance if this is asked in the wrong place.
I built the kit B1 with Korg triode.
Very nice kit and easy to follow instructions. Thank you.
But I have two issues. On power up, there is a roughly 6 Volt pulse that lasts for half a second or so. Is this normal?
And the volume control only goes to 7 from starting at 6 before it gets quite loud.
I'm sure I did something wrong, but can't find it.
Can someone please help?
Thanks,
Chuck
Hi,
New to this, so not sure where to ask these questions.
Sorry in advance if this is asked in the wrong place.
I built the kit B1 with Korg triode.
Very nice kit and easy to follow instructions. Thank you.
But I have two issues. On power up, there is a roughly 6 Volt pulse that lasts for half a second or so. Is this normal?
And the volume control only goes to 7 from starting at 6 before it gets quite loud.
I'm sure I did something wrong, but can't find it.
Can someone please help?
Thanks,
Chuck
Thanks for the reply.
The spike is measured at the output RCAs. And noticed in the woofer cone pushing out. I haven't tried turning on the amp after the B1. I will and see what happens.
I have looked at the volume pot wiring and it matches the pictures in the (well made) instructions, but I will do more research on it today.
The spike is measured at the output RCAs. And noticed in the woofer cone pushing out. I haven't tried turning on the amp after the B1. I will and see what happens.
I have looked at the volume pot wiring and it matches the pictures in the (well made) instructions, but I will do more research on it today.
Pics, please.
No... definitely don't hook it back up to any amplifier (particularly connected to any speakers that you actually care about) until resolved.
Once this issue is sorted, then... Yes, you should turn on your pre-amp prior to your amplifier, and turn them off in reverse order.
Power up - Source => Pre => Amp
Power down - Amp => Pre => Source
It often doesn't matter, but it's always a good practice/precaution.
No... definitely don't hook it back up to any amplifier (particularly connected to any speakers that you actually care about) until resolved.
Once this issue is sorted, then... Yes, you should turn on your pre-amp prior to your amplifier, and turn them off in reverse order.
Power up - Source => Pre => Amp
Power down - Amp => Pre => Source
It often doesn't matter, but it's always a good practice/precaution.
A quick question of wiring the Korg when using the Meanwell 24v psu as recommended in the thread and I followed post #1396. I did the wiring by connecting all left channels (inputs/outputs) grounds together and then all right channels (inputs/outputs) using copper winding wire. The RCA jacks are all isolated from the chassis. Using front panel dpdt switch 2+2+2 pins where the center pin is output and top/bottom are connected to the 2 RCA inputs.
All the mounting legs of the Korg board are isolated from the bottom panel using Nylon spacers. I am using a TKD 2CP 20k pot and the output from the dpdt toggle switch goes to the pot and outputs from pot to the Korg inputs. The grounds from the pot to the input grounds of Korg. Now when I play via a source and use headphone absolutely no issues with the usual microphonics because of the vibration otherwise pretty good sound and the volume also works fine. The volume pot is also not connected to the chassis and isolated. This is the first time I am using a switching external psu as always I have been using a RCORE and a psu inside the chassis. With the Meanwell switching PSU providing the direct 24vdc not sure if i am doing the wiring correctly.
Now when I connect this to the power amp and powering the amp after first switching on the Korg, a loud noise comes from the speakers. Not sure where the issue is as I see DC offset in the Korg outputs is around 0.6mV and my Apex FH9HV power amp has a speaker protection board which comes up fine and hence no issues with the offset or the amp. I am not sure where the issue is as all the wiring seems to be fine and the only suspect is the dpdt toggle switch.
Please look at some of the build pics with the wiring and let me know if something I am missing. By the way the power amp works fine with my other ACP preamp with the same source cables.
All the mounting legs of the Korg board are isolated from the bottom panel using Nylon spacers. I am using a TKD 2CP 20k pot and the output from the dpdt toggle switch goes to the pot and outputs from pot to the Korg inputs. The grounds from the pot to the input grounds of Korg. Now when I play via a source and use headphone absolutely no issues with the usual microphonics because of the vibration otherwise pretty good sound and the volume also works fine. The volume pot is also not connected to the chassis and isolated. This is the first time I am using a switching external psu as always I have been using a RCORE and a psu inside the chassis. With the Meanwell switching PSU providing the direct 24vdc not sure if i am doing the wiring correctly.
Now when I connect this to the power amp and powering the amp after first switching on the Korg, a loud noise comes from the speakers. Not sure where the issue is as I see DC offset in the Korg outputs is around 0.6mV and my Apex FH9HV power amp has a speaker protection board which comes up fine and hence no issues with the offset or the amp. I am not sure where the issue is as all the wiring seems to be fine and the only suspect is the dpdt toggle switch.
Please look at some of the build pics with the wiring and let me know if something I am missing. By the way the power amp works fine with my other ACP preamp with the same source cables.
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Yes its like very loud not continuously but immediately switching on it starts crackling kind of sound and within a few seconds I am switching off the power amp fearing I will blow the tweeters of the small Energy satellite speakers which I am using for testing. Seems like coming from the tweeters.
Thanks
NuTube Preamp build video
I just noticed this from Blueglow Electronics YouTube channel
diyAudio Passworks Korg NuTube Preamp Kit Build Tips & Hints
I just noticed this from Blueglow Electronics YouTube channel
diyAudio Passworks Korg NuTube Preamp Kit Build Tips & Hints