No intention of chauvinism, but the AH! is one heck of a CD-player. Herman has good ears and a keen eye for business.(the guy is like a skinny version of NP)
www.hifi-planet.com/ahnjoetjoeb4000home-en.htm
Motorola and even TI used to make a number of BD and BF devices in that longtail X17 package during the KSA100 days.
The ones that come to mind are Motorolas BD389/390.
100V / 1A / 25 watts, with lightning high Ft.
TI used to make 10 watter 250V BF615/616 and 300V BF617/618, but those were only good for 200mA.
Bare in mind that this KSA50 could be a modified version.
I seem to recall that the owner of the posted KSA50 resides somewhere overhere. In the late 80s and early 90s hacking together upgrades and conversions seemed a national sport.
I've contributed a few to the list of corpses myself.
Here's a pic of what those devices look like for the ones who are unfamiliar with them :
Of course P8535 stands for Philips, 1985, week 35.
Attachments
Hi,
using more than 4 pair will keep the output devices at a lower output current per device.
Combine the increased pairs with more modern higher hFE and the effect reduces the loading on the drivers considerably. So theoretically a single driver pair as KSA50 would be possible (if you avoid really low load impedance).
But, that brings me back to the question I posed some weeks ago.
What differences between the KSA50 and KSA100 result in the apparent improvement in bass response?
Could part of this improvement result from lower loading on the devices between LTP and output?
The improvement in highs could come from the second LTP or from the FET midstage, or from the extra stage between LTP and drivers.
BTW. the output boards from the KSA50 Klone, when doubled up, make an excellent 6pair (plastic packaged) KSA100 output stage.
Since I have most of the parts together for a dual driver, 6pair KSA50 with a Pd=250W , I am only a few devices and a PCB away from KSA100. Decision!
using more than 4 pair will keep the output devices at a lower output current per device.
Combine the increased pairs with more modern higher hFE and the effect reduces the loading on the drivers considerably. So theoretically a single driver pair as KSA50 would be possible (if you avoid really low load impedance).
But, that brings me back to the question I posed some weeks ago.
What differences between the KSA50 and KSA100 result in the apparent improvement in bass response?
Could part of this improvement result from lower loading on the devices between LTP and output?
The improvement in highs could come from the second LTP or from the FET midstage, or from the extra stage between LTP and drivers.
BTW. the output boards from the KSA50 Klone, when doubled up, make an excellent 6pair (plastic packaged) KSA100 output stage.
Since I have most of the parts together for a dual driver, 6pair KSA50 with a Pd=250W , I am only a few devices and a PCB away from KSA100. Decision!
If you consider how closely the older KSA100's (one of the five schematics I've seen so far anyway) resembles the KSA50 we have, it should be sensible to assume that the KSA100 MK2 boards can be used as KSA50 MK2's with a few minor changes to accommodate the lower supply voltage. That would be a more elegant approach than to start a whole new KSA50 clone project.
When i enlarge/sharpen the detail in PowerPoint it sorta looks like a GES logo.
Definitely not Motorola, but could be TIS(TI).
GE semiconductors was the only company to produce BD139/140s in a TO202 package, called BD139G/BD140G.
The longer flange neck definitely makes it a US production X17 imo.
European ones had the edges of the flanges really close to the body, like the Philips ones i posted.
Hi Flodstrom
I can find out from our local friendy pcb house, but in my experience he is not very economical on small qty single sided boards. Anything under 100 qty runs and your wasting your time. As a matter of interest, how big are your output boards? I can always just check...
I can find out from our local friendy pcb house, but in my experience he is not very economical on small qty single sided boards. Anything under 100 qty runs and your wasting your time. As a matter of interest, how big are your output boards? I can always just check...
This may be a dumb question, but couldn't the output boards be added to the end of the main board with scribes so that it can be separated? Something I bought had it done that way and it was pretty simple to snap off. I believe that saved money.
Blessings, Terry
Blessings, Terry
Output boards:
Output boards are double sided (70 or 105 µm Cu foil). Also I plan to use TO-3 sockets for the easy dismounting if testing different brands of outputs besides easy servicing if something blows.
These boards also have the drivers, including Q13 bias transistor fitted, but if this is not the way you want it just omit them.
Board dimension will be ca 13 inches in lenght x 3 inches wide (0.062 FR4, blue perhaps?)
This is the schematics for the two (pos and neg side) boards:
Regards 😎
Output boards are double sided (70 or 105 µm Cu foil). Also I plan to use TO-3 sockets for the easy dismounting if testing different brands of outputs besides easy servicing if something blows.
These boards also have the drivers, including Q13 bias transistor fitted, but if this is not the way you want it just omit them.
Board dimension will be ca 13 inches in lenght x 3 inches wide (0.062 FR4, blue perhaps?)
This is the schematics for the two (pos and neg side) boards:
Regards 😎
PCB's for the public?
You are out of control! A man on a mission? 😉 When can we get our grubby little paws on some PCBs for the 100.
Cheers,
Shawn.
Mark A. Gulbrandsen said:
You are out of control! A man on a mission? 😉 When can we get our grubby little paws on some PCBs for the 100.
Cheers,
Shawn.
Terry,
Since many will be using TO-3 OP devies a board has not yet been designed. Please do a design at your earl;iest convenience as I need them too! Yes, we could add these to the main board but we do not want to change the main board since it can also retrofit right into older Krell's directly.
For plastic jobs the present KSA-50 board could just be stretched to add one more device, or better yet split into 4 boards of two devices each sonce that translates directly to each drivers pair.
Flodstroem,
UNless you can't find or don't like the drivers heatsink on the pcb I can assure you that there is no stability problem not having them mounted on the main sinks. Thermal control is perfect the way it is. In fact it probably stabilizes faster this way since you don't have to heat up the whole amp up to allow it to stabilize... just the driver heat sink.
Mark
Since many will be using TO-3 OP devies a board has not yet been designed. Please do a design at your earl;iest convenience as I need them too! Yes, we could add these to the main board but we do not want to change the main board since it can also retrofit right into older Krell's directly.
For plastic jobs the present KSA-50 board could just be stretched to add one more device, or better yet split into 4 boards of two devices each sonce that translates directly to each drivers pair.
Flodstroem,
UNless you can't find or don't like the drivers heatsink on the pcb I can assure you that there is no stability problem not having them mounted on the main sinks. Thermal control is perfect the way it is. In fact it probably stabilizes faster this way since you don't have to heat up the whole amp up to allow it to stabilize... just the driver heat sink.
Mark
Sure, we already have a two type board for the input stage and a three type for the mosfets. MIght as well for the outputs, would dedinately same some cost on making boards.
Mark
Mark
Hi,
if using output boards for plastic packaged devices then the KSA50 Klone output boards with 3 devices on each board fed from one half of the driver stage would be best option. Results in 6pair of plastic cf 4pair of To3.
Some might like to use lower power rating plastics like MJW0302A/MJW0281A or MJL0302A/MJL0281A.
In that case a dual device board would be more usefull (8 boards instead of 4)
Most versatile could be a board for 4 devices(both TO3 as TO247) with scores and coupling pads, break to size. (Mmm, + MT200 ? 😀 )
Probably would make it the most universal output board around.
In that case a dual device board would be more usefull (8 boards instead of 4)
Most versatile could be a board for 4 devices(both TO3 as TO247) with scores and coupling pads, break to size. (Mmm, + MT200 ? 😀 )
Probably would make it the most universal output board around.
Krell On-off Switch- any chance of locating the original supplier?
Hi
Mark, thanks for the board decision- I just cannot wait to see the end product.
Now I just wondering- what are the chances that we can find similar on-off switches that Krell used with these amps ?
I for one would love to use the original flush mounting switch.
Jozua
Hi
Mark, thanks for the board decision- I just cannot wait to see the end product.
Now I just wondering- what are the chances that we can find similar on-off switches that Krell used with these amps ?
I for one would love to use the original flush mounting switch.
Jozua
Hi Mark,
I am probably one of those who will use TO-3 devices if I go with the tunnels I have. I am contemplating using the chassis from my Aleph-X though since I am dissatisfied with how it sounds anyway. I'm not sure if it has enough heatsink without some sort of fan but it is tempting to try. It is set up for plastic devices. If I use the two tunnels I will have two fans running and 24 TO-3 outputs for the two channels. I suppose I could just run 4 pair per side, but since I have enough devices and the tunnels accommodate 12 devices each, I don't see the harm in running 24. Someone correct me if I'm wrong.
Here's some pics of the tunnel.
Here's some pics of the Aleph-X chassis.
Blessings, Terry
I am probably one of those who will use TO-3 devices if I go with the tunnels I have. I am contemplating using the chassis from my Aleph-X though since I am dissatisfied with how it sounds anyway. I'm not sure if it has enough heatsink without some sort of fan but it is tempting to try. It is set up for plastic devices. If I use the two tunnels I will have two fans running and 24 TO-3 outputs for the two channels. I suppose I could just run 4 pair per side, but since I have enough devices and the tunnels accommodate 12 devices each, I don't see the harm in running 24. Someone correct me if I'm wrong.
Here's some pics of the tunnel.
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.
Here's some pics of the Aleph-X chassis.
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.
Blessings, Terry
Hi Still4given,
what temperatures did your tunnels achieve in the 50Klone @ what dissipation?
Looking at your pics the short tunnels taking 12devices may be a bit small.
I see nothing wrong with running 6pair for each channel, you just need to adjust the quiescent current for each so that the total matches the 100Klone requirement.
It will be dissipating about 260W per channel which is quite a bit more than the 50Klone and nearly matching the stereo pair of 50Klones (310W/pair).
I thought you complained about the fan noise, have you got used to it? or found a solution?
what temperatures did your tunnels achieve in the 50Klone @ what dissipation?
Looking at your pics the short tunnels taking 12devices may be a bit small.
I see nothing wrong with running 6pair for each channel, you just need to adjust the quiescent current for each so that the total matches the 100Klone requirement.
It will be dissipating about 260W per channel which is quite a bit more than the 50Klone and nearly matching the stereo pair of 50Klones (310W/pair).
I thought you complained about the fan noise, have you got used to it? or found a solution?
AndrewT said:
I'll have to look back to see what temp I had. I am running 12 devices on the tunnel for the KSA50 in stereo. It doesn't over heat though. You are right, I did complain about the fan noise. I think it is because it is in my little studio and it sits at ear-level, about a foot away from a painted drywall wall. I believe if it were in a rack in a carpeted room it wouldn't be too objectionable. The solution I found for the fan noise was a Symasym, but we probably shouldn't go there again. 😀
This is how the tunnel looks in my KSA50 Klone.
Blessings, Terry