Hi Guys,
I've got my main boards stuffed and my MJ15003/4's mounted in my heatsinks. I plan to hard wire the resistors to the sockets. Am I correct in assuming that since I am not using the feedback circuit that I don't need RV1,2 & 3?
Also, What would be the bests value for RB 1, 2 & 3 and RE 1, 2 & 3 with these TO-3's?
Does Rail voltage come into play for the values?
I am planning to use a single Power Transformer that is 30-0-30 500vA.
Thanks, Terry
I've got my main boards stuffed and my MJ15003/4's mounted in my heatsinks. I plan to hard wire the resistors to the sockets. Am I correct in assuming that since I am not using the feedback circuit that I don't need RV1,2 & 3?
Also, What would be the bests value for RB 1, 2 & 3 and RE 1, 2 & 3 with these TO-3's?
Does Rail voltage come into play for the values?
I am planning to use a single Power Transformer that is 30-0-30 500vA.
Thanks, Terry
Rb s...
...are not necessary and should be 0 ohms, ie use wire shorts.
Rvi are used for the output current limiter, which for 3 pairs of to3's is essentially unneccessary, allowing you to skip all those parts whose numbers are in the 300's
Re should be somewhere between 0.5 and 1 ohm, with 0.68 being the value I and a few others have used. IIRC, one person used much lower values (0.15ohm) successfully, the benefit being slightly greater output. There is a chance of bias instability and high adjustment sensitivity with the lower values. The more output pairs in parallel, the higher the value can be used. For the KSA100, krell had 4 output pairs and 1ohm resistors.
I am considering using 1.36 or 2.04 ohm (ie 2 or 3 x 0.68) ohms for the 16 output pair amp...just a lot of work to solder all those resistors, and I am lazy...time to shop for 2ohm 3w resistors I guess...
Under extreme conditions the output emitter resistors can get hot, they may be slightly warm under normal output conditions.
HTH
Stuart
...are not necessary and should be 0 ohms, ie use wire shorts.
Rvi are used for the output current limiter, which for 3 pairs of to3's is essentially unneccessary, allowing you to skip all those parts whose numbers are in the 300's
Re should be somewhere between 0.5 and 1 ohm, with 0.68 being the value I and a few others have used. IIRC, one person used much lower values (0.15ohm) successfully, the benefit being slightly greater output. There is a chance of bias instability and high adjustment sensitivity with the lower values. The more output pairs in parallel, the higher the value can be used. For the KSA100, krell had 4 output pairs and 1ohm resistors.
I am considering using 1.36 or 2.04 ohm (ie 2 or 3 x 0.68) ohms for the 16 output pair amp...just a lot of work to solder all those resistors, and I am lazy...time to shop for 2ohm 3w resistors I guess...
Under extreme conditions the output emitter resistors can get hot, they may be slightly warm under normal output conditions.
HTH
Stuart
Hi Stuart,
Can I then just wire the P. output and N. output directly to their respective bases of Q1- Q3 and then 0.68 3W resistors between Q1, Q2 & Q3 emitters and the speaker jacks? I'm not planning on using the output boards at all. Should I use some heatsinks on the emitter resistors?
Thanks, Terry
Can I then just wire the P. output and N. output directly to their respective bases of Q1- Q3 and then 0.68 3W resistors between Q1, Q2 & Q3 emitters and the speaker jacks? I'm not planning on using the output boards at all. Should I use some heatsinks on the emitter resistors?
Thanks, Terry
still4given said:
WHOA! I see that the feedback circuit connects to a number of circ componets. I think you need to use the feedback circ even with no protection (300 series numbered components) installed.
Have I got this right or is FB not necessary with no protection components installed?
output wiring...
Terry,
I hard wired the emitter resisters to the transistor sockets and then collected the output from the junction of all the resistors using a 10 gauge bare copper bus wire. The bases & collectors are hard wired together, with 24 gauge wire for the bases and a 16 gauge wire for each collector, finally using a 10 gauge run from the emitter resistor junction to the output jack, and from the collectors to the power supply caps...
The emitter resistors don't need a heatsink, just room to breath...they are designed to dissipate their rated level of power without additional heatsinking, but they do need 'fresh' air to be able to move around them...
Stuart
Terry,
I hard wired the emitter resisters to the transistor sockets and then collected the output from the junction of all the resistors using a 10 gauge bare copper bus wire. The bases & collectors are hard wired together, with 24 gauge wire for the bases and a 16 gauge wire for each collector, finally using a 10 gauge run from the emitter resistor junction to the output jack, and from the collectors to the power supply caps...
The emitter resistors don't need a heatsink, just room to breath...they are designed to dissipate their rated level of power without additional heatsinking, but they do need 'fresh' air to be able to move around them...
Stuart
pay no attention to the...
...components labelled 30x, ie q30x, c30x, r30x, d30x. They have no function in the circuit other than current limiting. The feedback point is from the juntion of the emitter resistors, which is also the output. This is why the components for the current limiter connect there...
None of the 5 channels I've built (or any that krell built) included Rvi or any of the 30x components, they all work perfectly...
Stuart
...components labelled 30x, ie q30x, c30x, r30x, d30x. They have no function in the circuit other than current limiting. The feedback point is from the juntion of the emitter resistors, which is also the output. This is why the components for the current limiter connect there...
None of the 5 channels I've built (or any that krell built) included Rvi or any of the 30x components, they all work perfectly...
Stuart
When can we expect an update on Brian's KSA50 pages?
Neychi, which boards are they then?
Today I cleaned up my main heatsinks on the milling machine (the sawing got a bit ugly). Tommorow still some small deburring job and washing of the petrolium and I can start moving parts around trying to find a good layout for my amps.
Neychi, which boards are they then?
Today I cleaned up my main heatsinks on the milling machine (the sawing got a bit ugly). Tommorow still some small deburring job and washing of the petrolium and I can start moving parts around trying to find a good layout for my amps.
And here is the reply from Advanced regarding the board, changes, and holes sizes.........
"there are no standard sizes really....
what you will need to do is just do your changes and then send me the
gerbers so i can quote them.
if the changes/charges are minimal then it's no big deal but i can't
really comment on if there would be
an additional charge without seeing the changes......
no worries, we'll take care of you!"
So Al, perhaps I can check with Brian GT on what hole sizes he used for the rail feeds and such. Moving the foil away from the board mounting holes should be a trivial thing. It soulds like as long as we don't make too many changes we will stay at the same price with no additional charges. I mentined 10 to 12 hole size changes to them.
Mark
"there are no standard sizes really....
what you will need to do is just do your changes and then send me the
gerbers so i can quote them.
if the changes/charges are minimal then it's no big deal but i can't
really comment on if there would be
an additional charge without seeing the changes......
no worries, we'll take care of you!"
So Al, perhaps I can check with Brian GT on what hole sizes he used for the rail feeds and such. Moving the foil away from the board mounting holes should be a trivial thing. It soulds like as long as we don't make too many changes we will stay at the same price with no additional charges. I mentined 10 to 12 hole size changes to them.
Mark
Actually I maintain that web page and am new to doing so. However there will not be any more updates to it until the board is finalized and is being produced..... or when Al sends me the Eagle file photos of the top/bottom so they can be posted.
I have also been VERY busy at work the last month and a half and spend alot of time on the road in Idaho, Montana, and Wyoming...... not complaining though as it sure beats driving around the jungles of Northern Illinois, Indiana and Southern Wisconsin that I used to drive..... I do carry my laptop and keep in touch with this thread as I can.
Mark
WOW i've missed SOOOO much!!!!
Damn, we need someone to summarise the last 30-40 pages for me!!! hahahaha...... There's too much to read - any new revelations - or is it still talking about the "new" krell clone boards???
Mine are still running 100% - sound EXCELLENT and i love them
Aaron
Damn, we need someone to summarise the last 30-40 pages for me!!! hahahaha...... There's too much to read - any new revelations - or is it still talking about the "new" krell clone boards???
Mine are still running 100% - sound EXCELLENT and i love them
Aaron
Al,
Here is what Brian did for his hole sizes.........
"For the mini-A boards, the main output pads are 80mil/175mil (inner hole/outer pad diameter). It seemed that this would accomidate most wire sizes.
On the Mini-A circuit boards, I used 80/150mil to keep the clearances in line for the pads."
Hope this helps.
Mark
Here is what Brian did for his hole sizes.........
"For the mini-A boards, the main output pads are 80mil/175mil (inner hole/outer pad diameter). It seemed that this would accomidate most wire sizes.
On the Mini-A circuit boards, I used 80/150mil to keep the clearances in line for the pads."
Hope this helps.
Mark
Well I sat down to hook everyting up last night and couldn't find the resistors for RE1-3. Either I misplaced them or forgot to order them. I hate that. I going to go to Mar-Vac today and see if they carry them. Is .5ohm 5W the resistor of choice for these? I see it says 0.2ohm-1ohm in the parts list. Will any of those work equally well or should I get a certain value? Remember, my transformer is 30-0-30 VAC center tap. That's a little higher than the stock transformers.
Thanks, Terry
Thanks, Terry
Aaron,
So do you have your amps biased for 4ohm loads now?
Reason I ask, I was wondering if you noticed a big difference in the sound character of the amp as the bias was increasing...
I have about ~1A idle current in the big amp, I am thinking of increasing it further, but only just finished the assembly of the last half of the output stage. Don't want anything to pop unexpectedly.
Stuart
So do you have your amps biased for 4ohm loads now?
Reason I ask, I was wondering if you noticed a big difference in the sound character of the amp as the bias was increasing...
I have about ~1A idle current in the big amp, I am thinking of increasing it further, but only just finished the assembly of the last half of the output stage. Don't want anything to pop unexpectedly.
Stuart
Terry...
Given that you have 3 output pairs, I'd go with slightly higher rather than slightly lower...ie 0.68 versus 0.33.
If you give me your address I can send you the panasonic 10w/0r68, the same ones you've seen talked about in some of the other posts...of course the immediate gratification factor is much lower...
Stuart
Given that you have 3 output pairs, I'd go with slightly higher rather than slightly lower...ie 0.68 versus 0.33.
If you give me your address I can send you the panasonic 10w/0r68, the same ones you've seen talked about in some of the other posts...of course the immediate gratification factor is much lower...
Stuart