Hi Gabriel,
I've dscribed the effect of these mods earlier in this tread. I have only modded one channel of one amp so far to compare the effect of the mods.
I've dscribed the effect of these mods earlier in this tread. I have only modded one channel of one amp so far to compare the effect of the mods.
During the mods, the changing..........connection cable
Since dr.h and jwb change the capacitors of KMA-160,do you consider replacing the internal
connection cable?
I think it would be a new style sound of krell. I am going to try this.
How about letting us begin the experiment together?
🙂
Since dr.h and jwb change the capacitors of KMA-160,do you consider replacing the internal
connection cable?
I think it would be a new style sound of krell. I am going to try this.
How about letting us begin the experiment together?
🙂
Solid Copper bar is not so good
Copper bar may oxidize and get rust although it is solid and firm.
I consider use a better conductive material wire to modify the machine.
However, I made a little mod for my machines.
It is not very hard. Unscrew the back panel and you will find the AC power plug. Detach the the
wire of its original plug. Replacing the plug using ur screw driver.The profit is better sonic
image and transparency and sonic resolution. But it takes a few days to break in to feel the
maximum effects. here are some pics
1.Unscrew six back bottums
2.take the AC power plug
3.show the detached AC wire from original plug(it is not real krell wire, just a demo)
and put the different wire sides in the different tunnels of the plug.Then screw the wire tight.
4.reinstall it
and then screw back panel
Copper bar may oxidize and get rust although it is solid and firm.
I consider use a better conductive material wire to modify the machine.
However, I made a little mod for my machines.
It is not very hard. Unscrew the back panel and you will find the AC power plug. Detach the the
wire of its original plug. Replacing the plug using ur screw driver.The profit is better sonic
image and transparency and sonic resolution. But it takes a few days to break in to feel the
maximum effects. here are some pics
1.Unscrew six back bottums
An externally hosted image should be here but it was not working when we last tested it.
2.take the AC power plug
An externally hosted image should be here but it was not working when we last tested it.
3.show the detached AC wire from original plug(it is not real krell wire, just a demo)
An externally hosted image should be here but it was not working when we last tested it.
and put the different wire sides in the different tunnels of the plug.Then screw the wire tight.
4.reinstall it
An externally hosted image should be here but it was not working when we last tested it.
and then screw back panel
Gabriel raises an interesting point about the internal wire.
I tried an experiment:
In stock form, KRELL runs power supply wires for the second output PCB from the first output PCB.
I ran THICK wires DIRECTLY from the main supply to the second output PCB. There was no apparent change in sonics, but something else did change in a very positive way:
The music seemed to "swing" more, for example the bassist on Diana Krall's Love scenes really seemed to be having fun playing.
Sorry I know its sounds strange but there was something else other than improved treble bass etc. I've reversed the mod, but will implement again soon to see if it's still there after the capacitor changes.
I tried an experiment:
In stock form, KRELL runs power supply wires for the second output PCB from the first output PCB.
I ran THICK wires DIRECTLY from the main supply to the second output PCB. There was no apparent change in sonics, but something else did change in a very positive way:
The music seemed to "swing" more, for example the bassist on Diana Krall's Love scenes really seemed to be having fun playing.
Sorry I know its sounds strange but there was something else other than improved treble bass etc. I've reversed the mod, but will implement again soon to see if it's still there after the capacitor changes.
About internal wire
Thanks for Dr.H response, can you describe the material of the"Think" Wire,
different material will show different aspects in sound. I am still consider using what material
to my mods. Sometimes it really to try and error to make the best result.
Dr.H ,can you show some pics of your mod ?
Thanks
Thanks for Dr.H response, can you describe the material of the"Think" Wire,
different material will show different aspects in sound. I am still consider using what material
to my mods. Sometimes it really to try and error to make the best result.
Dr.H ,can you show some pics of your mod ?
Thanks
Dr.H said:
It is not strange but "swing" is a word of my favorite.I live a jazz life.I think wire mod is great but takes more consideration.Sometimes ¡§thick¡§wire is necessary.however, under some situations, material of wire is more important, even it is thin.
That's my experience.the double bass vivid feeling is normal because you give more current
for amp to drive the speaker.
My Mod partI
I change the internal wire of Krell KMA-400
the primary part I change is the wires connecting trasistor pcb, I think it will
affect the acoustic feeling.Therefore, I change it.I will later post the pics
and restore the amp for test listening.
I change the internal wire of Krell KMA-400
the primary part I change is the wires connecting trasistor pcb, I think it will
affect the acoustic feeling.Therefore, I change it.I will later post the pics
and restore the amp for test listening.
to Dr.H
Your mod about "Raise the value of the input and gain stage power supply caps".I saw your pics
but don't know which points should be connected the 4 capacitors in one box.
Please do me a favor.Thanks!
Your mod about "Raise the value of the input and gain stage power supply caps".I saw your pics
but don't know which points should be connected the 4 capacitors in one box.
Please do me a favor.Thanks!
MY Mod partI---internal wire replacement
I begin the mod is replacing the original wire. Here it is the original wires.
I replace them with taralab signal cable which contains 6 thick round copper wires per cord.
Here is the final pic
In addition , I think the signal wire input from RCA terminal should be modified.Here is the input
wire connection at the rear of the pcb.
Now we turn the pcb back, you will find a wire attached to the site
You can connect it to the RCA terminal ground. I replace it with kimber cable copper wire.
The part I is the easiest part and I finished it.
Here is the report of test listening.
You will feel more transparent in sound stage and get a more vivid sound image.
Besides, you will feel the sound become more neutral and balanced in all frequency.
The detail of music can be dig it more.That's interesting.
Part 2 I will change the caps on the pcbs.
Does anyone have a different feeling before and after changing the caps?
I begin the mod is replacing the original wire. Here it is the original wires.
An externally hosted image should be here but it was not working when we last tested it.
I replace them with taralab signal cable which contains 6 thick round copper wires per cord.
Here is the final pic
An externally hosted image should be here but it was not working when we last tested it.
In addition , I think the signal wire input from RCA terminal should be modified.Here is the input
wire connection at the rear of the pcb.
An externally hosted image should be here but it was not working when we last tested it.
Now we turn the pcb back, you will find a wire attached to the site
An externally hosted image should be here but it was not working when we last tested it.
You can connect it to the RCA terminal ground. I replace it with kimber cable copper wire.
An externally hosted image should be here but it was not working when we last tested it.
The part I is the easiest part and I finished it.
Here is the report of test listening.
You will feel more transparent in sound stage and get a more vivid sound image.
Besides, you will feel the sound become more neutral and balanced in all frequency.
The detail of music can be dig it more.That's interesting.
Part 2 I will change the caps on the pcbs.
Does anyone have a different feeling before and after changing the caps?
nice work Gabriel!
To add the caps use your multimeter to determine the positive ground and negative legs of the power suppply and the connect the caps.
To add the caps use your multimeter to determine the positive ground and negative legs of the power suppply and the connect the caps.
Think I got the swing back again
Using a snubber network (100R 33onF) on the rectifer diodes for the 100V supply results in a return of the swing I thought I heard on the bass on Diana Kralls album. I did NOT re-install the thicker wires and it does not seem that they're required.
Using a snubber network (100R 33onF) on the rectifer diodes for the 100V supply results in a return of the swing I thought I heard on the bass on Diana Kralls album. I did NOT re-install the thicker wires and it does not seem that they're required.
Oh yeah, one other small mod I completely forgot to mention. I replaced that teensy little ground lead on the input board with a whopping huge lead I salvaged from a telecom UPS. That helped kill off a buzz I was getting in both channels, and with my sensitive speakers that was quite a nuisance. The large ground lead silenced it.
the wonderful redesign
I mention the two blue blocks .They are what kind of spec. Where is the jumper you add?
Please advise.
Thanks!
I mention the two blue blocks .They are what kind of spec. Where is the jumper you add?
Please advise.
Thanks!
They are very large value, but I forget exactly. Probably 3.3uF or 10uF. You can see one of the jumpers adjacent to the capacitor in the photo.
JWB,
I assume that those blue caps are now sitting in the signal path and are there to block DC?
Is there any reason you chose to put caps in the path?
Are you concerned about a fault developing?
Gabriel, you should try the snubbers on the 100V supply diodes. I would have done the thick wire mod again, but it seemed like a lot of work!
I assume that those blue caps are now sitting in the signal path and are there to block DC?
Is there any reason you chose to put caps in the path?
Are you concerned about a fault developing?
Gabriel, you should try the snubbers on the 100V supply diodes. I would have done the thick wire mod again, but it seemed like a lot of work!
My amps were destroyed under the care of their previous owner when the DC servo overheated and caught fire. Therefore the blocking caps seemed prudent. As I mentioned, there are jumpers which optionally bypass the blocking caps. With my old, floating preamp I used the blocking caps, but with my new earthed and balanced preamp I short them out.
Brief update
I listened more extensively yesterday and can confirm that the mods enhance detail and tighten the bass.
But, on poorer recordings, the sound can be "hard" on the ear, especially treble.
In comparison, the unmodded channel sounds laid back and less detailed, but also does not exhibit the treble hardness I refer to.
I will be trying a constant current source on the zeners (75V and 39V) shortly.
I listened more extensively yesterday and can confirm that the mods enhance detail and tighten the bass.
But, on poorer recordings, the sound can be "hard" on the ear, especially treble.
In comparison, the unmodded channel sounds laid back and less detailed, but also does not exhibit the treble hardness I refer to.
I will be trying a constant current source on the zeners (75V and 39V) shortly.