Mark A. Gulbrandsen said:
Folks, sorry to inform you this: I have tried to contact John at Victoria Magnetics two times and newer received an answer. Why? Maybe he isnt interested to make big transformers for the Krell project ?
I have spent a lot of time and energy several times for to explain to him what type of x-former we would like to buy and also that we wanted a price quotation for different price brakes, but no response at all.
What do we do next?
Someone in the UK or further south ready to take over???
Regards
PSU Cap update
Gentlemen
I have just replaced my 100.1 main PSU caps with new Sprague's. I did the same about 2 months with my 100.2.
I can hear that the caps still need to play in as the amp is at this stage not as transparent as before but the midrange is fuller and the dynamics are awesome. This is the sound that impressed me 20 years ago...
Subjectively it seems to me as if the imaging is more solid than the 100.2 which sometimes gives the impression as if the vocalist is moving around in front of the mike.
Regards
Jozua
Gentlemen
I have just replaced my 100.1 main PSU caps with new Sprague's. I did the same about 2 months with my 100.2.
I can hear that the caps still need to play in as the amp is at this stage not as transparent as before but the midrange is fuller and the dynamics are awesome. This is the sound that impressed me 20 years ago...
Subjectively it seems to me as if the imaging is more solid than the 100.2 which sometimes gives the impression as if the vocalist is moving around in front of the mike.
Regards
Jozua
Flodstroem said:
Folks, sorry to inform you this: I have tried to contact John at Victoria Magnetics two times and newer received an answer. Why? Maybe he isnt interested to make big transformers for the Krell project ?
I have spent a lot of time and energy several times for to explain to him what type of x-former we would like to buy and also that we wanted a price quotation for different price brakes, but no response at all.
What do we do next?
Someone in the UK or further south ready to take over???
Regards
If you e-mail me the specifications, so that I have them in front of me to discuss with John, I'll try to reach him via the telephone.
Maybe worth a try, no promises.
Cheers,
Ryan
Thanks guys. When I went home and had a look at the circuit diagram it was soooooo obvious.
On another note - I measured a few of the resistors that I had soldered onto my board the previous night and could not believe that the meter reading was all over the place. It varied like it does when you put it across a cap. When I turned over the board I noticed that there was green corrosion on some of the gold tracks where the flux had been. I rang the guy who sold me the "silver" solder and he told me that they use a aggresive flux and I should clean the board with water after soldering. The resistor readings went back to normal after the wash.
I think I might go back to using the old solder with lead.
On another note - I measured a few of the resistors that I had soldered onto my board the previous night and could not believe that the meter reading was all over the place. It varied like it does when you put it across a cap. When I turned over the board I noticed that there was green corrosion on some of the gold tracks where the flux had been. I rang the guy who sold me the "silver" solder and he told me that they use a aggresive flux and I should clean the board with water after soldering. The resistor readings went back to normal after the wash.
I think I might go back to using the old solder with lead.
This will for sure make it sound better, but only if you use magic rocks and the $500 wooden knob...Harry3 said:
http://cgi.ebay.com/4-Western-Elect...oryZ3284QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
Bob G.
I'm just wondering, I've got a pair of KSA100 boards and I'd like to use them to build a KSA50 if possible. Should I just built it like a regular KSA100 but with reduced bias and a power supply suited to KSA50 rail voltages? Building a real KSA100 would not only bankrupt me but would be much more power than I need. In fact, I barely need more than 15 watts...I wonder why I bother...anyway I had planned to use five pairs of MJL21193/4, TO-3P per channel.
You cannot build a true KSA50 with these boards, the circuit design is different in quite a few key areas. You can halve the output transistors and halve the drivers and halve the total bias (or just halve the bias), but you would end up with a low-biased-KSA100 and not a KSA50. Whether a 50W-biased KSA100 would sound better than a true KSA50 is open for debate, any takers?
I have been carefully examining the schematics of both amplifiers to the best of my non-engineer abilities and it seems reasonable to think a KSA-100 running at 50 watts per channel might be at least as good as a true KSA-50 clone. Unlike the KSA50 it has two sets of drivers, something that stood out to me. I wanted to use ten devices per channel, but this will mean one set of drivers is driving two pairs while the other drives three. Is this going to cause a problem? I need to use at least eight devices anyway because I am using plastic case transistors. I could not find any decent TO-3 heatsinks.
Also, I have asked this question in the KSA-50 thread several times before and rather frustratingly, never gotten an answer. I would like to use a capacitance multiplier power supply as described by Rod Elliott here. This will not only allow me to use a four-secondary(4x 39-0-39) transformer which I can get for a good price, but also I will have the only Krell clone to have anything other than an unregulated power supply. Not true regulation but it avoids a lot of regulator headaches. I read some posts in the KSA-50 thread where a CRC PS was being discussed. Some comments by AndrewT indicated that much of the KSA-50's 'slam' comes from large capacitor reserves. As the main capacitor banks are going to be isolated from the output by the capacitance multiplier the same way they would have been isolated by the resistors in the CRC supply, I'm a little worried that I'm going to lose this subjective 'slam' because I won't have more than 15,000uF per rail on the multiplier's output i.e. the first place the amplifier dips into for current reserve. Actually, Mr. Elliott says that exceeding 4700 uF on the multiplier supply's output is not recommended due to high charging currents, but I have to ask the dummy's question: What will be the consequences of using 15,000 uF caps on the power supply output? 4700 uF simply doesn't seem like enough reserve for this much iron. Will I need even more? Can I use more?. The supply is originally designed to power a JLH style Class A amp, but those don't push nearly the kind of power a KSA-50 does so I need to adapt it to its new environment.
thanks
Oh, and I updated the KSA-100 wiki to include a link to the KSA-50 wiki and since we didn't have one, there is now a Krell-o-Tracker for KSA-100 builds. Please post your information on the wiki!
Also, I have asked this question in the KSA-50 thread several times before and rather frustratingly, never gotten an answer. I would like to use a capacitance multiplier power supply as described by Rod Elliott here. This will not only allow me to use a four-secondary(4x 39-0-39) transformer which I can get for a good price, but also I will have the only Krell clone to have anything other than an unregulated power supply. Not true regulation but it avoids a lot of regulator headaches. I read some posts in the KSA-50 thread where a CRC PS was being discussed. Some comments by AndrewT indicated that much of the KSA-50's 'slam' comes from large capacitor reserves. As the main capacitor banks are going to be isolated from the output by the capacitance multiplier the same way they would have been isolated by the resistors in the CRC supply, I'm a little worried that I'm going to lose this subjective 'slam' because I won't have more than 15,000uF per rail on the multiplier's output i.e. the first place the amplifier dips into for current reserve. Actually, Mr. Elliott says that exceeding 4700 uF on the multiplier supply's output is not recommended due to high charging currents, but I have to ask the dummy's question: What will be the consequences of using 15,000 uF caps on the power supply output? 4700 uF simply doesn't seem like enough reserve for this much iron. Will I need even more? Can I use more?. The supply is originally designed to power a JLH style Class A amp, but those don't push nearly the kind of power a KSA-50 does so I need to adapt it to its new environment.
thanks
Oh, and I updated the KSA-100 wiki to include a link to the KSA-50 wiki and since we didn't have one, there is now a Krell-o-Tracker for KSA-100 builds. Please post your information on the wiki!
Hi,
The Capacitance multiplier gets different reviews depending on who's listening and what type of amplifier is being supplied.
It would be a worthwhile experiment to listen to the KSA50 on simple and rCRC and CMult supplies to hear the differences.
The really big advantage of the multiplier applies to ClassA amps where significant mains ripple gets past the first stage capacitance and can give rise to hum on the output when signal levels are low.
Output impedance is not as low as a regulated supply and this may affect the way the KSA50 sounds.
If you were to separate the supplies for the voltage amp from the driver and output stage then rail hum problems disappear.
I think and may still try a dual driver version of the KSA50 using the output stage of the KSA100 as a reasonable way to go.
It would be possible, but wasteful, to convert the 100PCB to 50duty by linking across the omitted components.
The Capacitance multiplier gets different reviews depending on who's listening and what type of amplifier is being supplied.
It would be a worthwhile experiment to listen to the KSA50 on simple and rCRC and CMult supplies to hear the differences.
The really big advantage of the multiplier applies to ClassA amps where significant mains ripple gets past the first stage capacitance and can give rise to hum on the output when signal levels are low.
Output impedance is not as low as a regulated supply and this may affect the way the KSA50 sounds.
If you were to separate the supplies for the voltage amp from the driver and output stage then rail hum problems disappear.
I think and may still try a dual driver version of the KSA50 using the output stage of the KSA100 as a reasonable way to go.
It would be possible, but wasteful, to convert the 100PCB to 50duty by linking across the omitted components.