!
New staff on boraomega web page.
NEW - KIT-s available soon!
http://bas.elitesecurity.org/kit-eng.html
New staff on boraomega web page.
NEW - KIT-s available soon!
http://bas.elitesecurity.org/kit-eng.html
Yes, I hope to be in a position to offer some audiophiles grade KIT-s soon. I will probably start with 40W class A design CALOR with top grade components, but I also hope to offer some other my designs if there is enough interest.
Meanwhile, a young audiophile and DIY enthusiast Mr. Manjos, with nick name= MICRO, successfully tested a prototype of my new design CROSER and reported excellent results.
Meanwhile, a young audiophile and DIY enthusiast Mr. Manjos, with nick name= MICRO, successfully tested a prototype of my new design CROSER and reported excellent results.
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Oh!.... Calôr is hot, chaude, heat, calore... and this i have a lot down here
in South America.... i am really feeling the Global warming.... last summer the temperature (average) was 2 degrées less...i am melting alike an ice cream under the sunligth.
Good you have a new amplifier...i hope next one will be cool, or cold, or freeze, or frozzen.
regards,
Carlos
........................................................................................................
Dear Bora, a question:
- Why have you decided to use FETs as drivers into the Closer?.... are they interesting into this position or you are using it for other reasons...fashion or politically correct behavior...more acceptable to your customer population, region, area...or something.
Are they better to that position dear Bora?
Thank you in advance by your attention...if prefer to answer directly, as you know, my e mail adress is always opened to you and to receive mails and messages from you is a big pleasure to me.
in South America.... i am really feeling the Global warming.... last summer the temperature (average) was 2 degrées less...i am melting alike an ice cream under the sunligth.
Good you have a new amplifier...i hope next one will be cool, or cold, or freeze, or frozzen.
regards,
Carlos
........................................................................................................
Dear Bora, a question:
- Why have you decided to use FETs as drivers into the Closer?.... are they interesting into this position or you are using it for other reasons...fashion or politically correct behavior...more acceptable to your customer population, region, area...or something.
Are they better to that position dear Bora?
Thank you in advance by your attention...if prefer to answer directly, as you know, my e mail adress is always opened to you and to receive mails and messages from you is a big pleasure to me.
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If you have time, it will be best if you culd visit this: http://www.diyaudio.com/forums/showthread.php?s=&threadid=134789
Most answers are there, but if necessary, I can write to you directly.
Most answers are there, but if necessary, I can write to you directly.
Thank you .... wise decision...to discuss or comment technical design decisions will
attract boring theorists to discuss, argue and re-design your amplifier...clever..... you are the one have a head to protect the brain...not only as hair support or lyce skidding track.
You have a brain and know how to use it....good.
hehehehe.
Carlos
attract boring theorists to discuss, argue and re-design your amplifier...clever..... you are the one have a head to protect the brain...not only as hair support or lyce skidding track.
You have a brain and know how to use it....good.
hehehehe.
Carlos
stage master mk 2
dear sir
greetings i built dr boras hexfet amplifier stage master mk 2
has 12 irfp 240 in output stage supply 95 volts dc plus minus no
problem with amplifier only want to find out it states 500 WATTS IN
8 OHMS can it be USED SAFELY IN 4 OHMS or is for 8 ohms use only
have tried many times to contact dr bora but with no luck hoping
i can get a reply
thanking you
andrew lebon
dear sir
greetings i built dr boras hexfet amplifier stage master mk 2
has 12 irfp 240 in output stage supply 95 volts dc plus minus no
problem with amplifier only want to find out it states 500 WATTS IN
8 OHMS can it be USED SAFELY IN 4 OHMS or is for 8 ohms use only
have tried many times to contact dr bora but with no luck hoping
i can get a reply
thanking you
andrew lebon
Which address you used Andrew? You can use StageMaster MK2 with 4 ohms loads but don't turn Volume to max! Amp will try to produce at least two times more power but overall dissipation will be above rated for all those devices. Have on mind that real life loads are seldom purely resistive!
Hello Dr Bora
I just find two toroidal transformer for the amp 27.5-0-27.5VAC 265VA each .
The transformer firs I tought to use the VA rating was to small for two channel and the voltage was a bit to high 30-0-30V AC. The capacitor (1000uF only 40V rated ) I do not want to change those capacitors (made by Frako) I did some test in a another amp about the 1000uF capacitors in the Symasym amp about two years a go . I did com pared many different caps like Panasonic FC series , Rubicon , Nichicon Muse etc but the Frako was far the best capacitor . Of course I didn't kept the Symasym amp it sounded somehow to thin with my speakers .?? Not my taste . Not much involving into the music .Somehow sound dry and almost clinical like the M Hiraga . I know many people say all capacitors are the same but that is far from the reality .I did tested one channel com pair to another channel with same set up . I can tell there is a huge difference between capacitors . Of course sometimes is more important which capacitor feet better in the project you working on . Even BG can sound bad in some circuit .
So now son I can set up at least one side and test it .
I will definitely let you know the result .
I spent to much money on it , it would be vaster to not to finish it .
I have a question do I need a preamp or if I use a pot that would be OK ? Or I need min. a buffer ?
Regards
I just find two toroidal transformer for the amp 27.5-0-27.5VAC 265VA each .
The transformer firs I tought to use the VA rating was to small for two channel and the voltage was a bit to high 30-0-30V AC. The capacitor (1000uF only 40V rated ) I do not want to change those capacitors (made by Frako) I did some test in a another amp about the 1000uF capacitors in the Symasym amp about two years a go . I did com pared many different caps like Panasonic FC series , Rubicon , Nichicon Muse etc but the Frako was far the best capacitor . Of course I didn't kept the Symasym amp it sounded somehow to thin with my speakers .?? Not my taste . Not much involving into the music .Somehow sound dry and almost clinical like the M Hiraga . I know many people say all capacitors are the same but that is far from the reality .I did tested one channel com pair to another channel with same set up . I can tell there is a huge difference between capacitors . Of course sometimes is more important which capacitor feet better in the project you working on . Even BG can sound bad in some circuit .
So now son I can set up at least one side and test it .
I will definitely let you know the result .
I spent to much money on it , it would be vaster to not to finish it .
I have a question do I need a preamp or if I use a pot that would be OK ? Or I need min. a buffer ?
Regards
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gaborbela said:
Hi friend!
DOGC-MK3 is designed for +/-42V DC supply and it is shame that your electrolytic caps are limiting factor forcing you to reduce that voltage. But, that's your decision. Just expect less power… say… 50-60W.
I know you will be pleasantly surprised with fullness and depth of sound of DOGC-MK3 compared to Symasym, even thou Symasym is a very good design but it might be that it don’t suite your “taste”.
In most cases you will need some kind of preamp and a high quality pot but I don’t think you need a buffer. DOGC-MK3 will certainly work even without preamp but it is very likely that you won’t be able to excite it to full power with standard output levels form today’s CD players and alike. If you decide to build matching preamp, I suggest you to wait a little. That my preamp (FlatBT) should be available soon as a KIT, because I am starting very soon to offer internationally some of my better designs as KIT-s, as well as separate PCB-s for some of them! Both DOGC-MK3 and FlatBT should be on the list!
I just noticed on your picture, left and right heatsinks are not of the same size (and thermal capabilities!) and I am not so sure that even bigger one (left one) will be acceptably hot!? You might easily be faced with a need for better heatsinks! If you don’t want to change heatsinks all you can do is to remove one resistor of 3,9ohms (originally there are two of them in parallel ) and that will half the quiescent current through driver pair and reduce heating on idle.
Hello Dr Bora
Yes one heat sink look bigger on the picture but the another one is a bit longer and taller . It is hard to see on the picture .
Both have almost the same weight .
I did made some holes on the bottom of the case were is the heat sink so the air can flow between the heat sink .
I will test it like these , if there is a need I will reduce the Iq a bit .
Both heat sink were removed from 7x100W home theater amplifier .
I hope they will be OK .
I have some preamp project , already working on the Kaneda and Aleph 1.7 preamp . The Aleph almost ready .
I just wanted to know how I set up the amp . But after your advice I will use it as a power amp .
My power transformers will give exact +/-40 DC . The 27.5-0-27.5 that is AC .
Thanks for your help .
Greetings from Toronto
Yes one heat sink look bigger on the picture but the another one is a bit longer and taller . It is hard to see on the picture .
Both have almost the same weight .
I did made some holes on the bottom of the case were is the heat sink so the air can flow between the heat sink .
I will test it like these , if there is a need I will reduce the Iq a bit .
Both heat sink were removed from 7x100W home theater amplifier .
I hope they will be OK .
I have some preamp project , already working on the Kaneda and Aleph 1.7 preamp . The Aleph almost ready .
I just wanted to know how I set up the amp . But after your advice I will use it as a power amp .
My power transformers will give exact +/-40 DC . The 27.5-0-27.5 that is AC .
Thanks for your help .
Greetings from Toronto
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Hello Dr Bora
I forget to tell you the main reason I changed the transformer not the capacitors . The first transformer I wanted to use is not strong enough . It would be good only for one channel . Or I must decrease the quiescent current at half or less .
I find these toroid's with good VA rating 265VA each , I will use two.
After the listening test I will be sure if I need a preamp or I would be OK with the amp how it is with a Alps Blue velvet pot .
I have a CD player with adjustable output level .I will test with that first .
If I remember well you wrote the Iq is now set up 400mA .
In case if the heat sink would be to small I reduce it to 300mA or so .
I even built 8W amplifier and even that was loud enough . I listen Jazz , Classical , Gospel music .
I have a Visaton speakers uses AL130 mid woofers tend to sound a bit dry (alum membrane) but very nice clean . I had the same size Revelator from Scan speak and I chose the Visaton over .
The Symasym is well design amp but not my taste , at least not in my system and some of my friend had the same opinion .
Thank you
Regards
I forget to tell you the main reason I changed the transformer not the capacitors . The first transformer I wanted to use is not strong enough . It would be good only for one channel . Or I must decrease the quiescent current at half or less .
I find these toroid's with good VA rating 265VA each , I will use two.
After the listening test I will be sure if I need a preamp or I would be OK with the amp how it is with a Alps Blue velvet pot .
I have a CD player with adjustable output level .I will test with that first .
If I remember well you wrote the Iq is now set up 400mA .
In case if the heat sink would be to small I reduce it to 300mA or so .
I even built 8W amplifier and even that was loud enough . I listen Jazz , Classical , Gospel music .
I have a Visaton speakers uses AL130 mid woofers tend to sound a bit dry (alum membrane) but very nice clean . I had the same size Revelator from Scan speak and I chose the Visaton over .
The Symasym is well design amp but not my taste , at least not in my system and some of my friend had the same opinion .
Thank you
Regards
gaborbela said:
Yes, those two transformers will do the job nicely! But you got it wrong about quiescent current of the drivers! With two parallel 3,9ohms resistors drivers will pass about 320-330mA (not 400mA!) and if you remove one resistor current will drop on about 170-175mA. In idle state, outputs are practically without any quiescent current… maybe just a few tens of uA.
Be very careful about handling of the input MOSFET-s IRFD. Some people damaged them (I don’t know how) even before first turn-on?! Use protective resistors (about 10-15ohms/10-17W each) one in each supply rail! Don’t turn the amp on without them!!!
Hello Dr Bora
Yes I miss understood the Iq .
I have a question , when U removed one 3.9 resister from the parallel do you hear any degrading in the sound ?
In that case the original transformer I planed to use would do the job well at list a think .
Right now I live it with the toroid's after I will test it with the another transformer two .
I connected a 200W light bulb as a load one side of the transformer secondary. With that load or without the 200W load I measured 0.2 voltage decrease . These little decrease probably not because the load ,mostly the transformers sec voltage tend to go higher with out any load than the real secondary voltage given on paper .
May be that transformer not bad either ?
I will see I will do the test at first with the toroid's .
I'd like your tube preamp , do that would be good to drive the DoGC III ? I only do not understand what type of relays U use on the boards .
Thank you !
Regards
Yes I miss understood the Iq .
I have a question , when U removed one 3.9 resister from the parallel do you hear any degrading in the sound ?
In that case the original transformer I planed to use would do the job well at list a think .
Right now I live it with the toroid's after I will test it with the another transformer two .
I connected a 200W light bulb as a load one side of the transformer secondary. With that load or without the 200W load I measured 0.2 voltage decrease . These little decrease probably not because the load ,mostly the transformers sec voltage tend to go higher with out any load than the real secondary voltage given on paper .
May be that transformer not bad either ?
I will see I will do the test at first with the toroid's .
I'd like your tube preamp , do that would be good to drive the DoGC III ? I only do not understand what type of relays U use on the boards .
Thank you !
Regards
gaborbela said:
Friend, “on ears” i.e. just by listening, you won’t be able to notice any degradation except if you are the one with “golden ears”! Precise instruments might reveal some degradations but I was never able to confirm that just by listening.
It is better to use separate transformers for each channel if you can, so don’t try to save on that! Quality of the amp and it’s sound is such that you will soon realize what I am talking about! It is worth that investment.
My tube preamp ADAGIO is absolutely top choice as a companion to the DOGC-MK3. That combination was in my setup for a few months, and some friends audiophiles and designers were amazed with overall fullness, resolution and soundstage of that combination especially with demanding classical music and jazz (that’s what I am mostly listening anyway).
Those relays you are talking about are so called “REED relays” in a DIL case, and they are nothing special but have some favorable characteristics when switching behavior is in question. They are widely available from majority of the respectable suppliers.
Hello Dr Bora
After I finish the DoGC MK3 and if I will be satisfied(probably I will) I think I will build one more amplifier from your collection .
I would like to build the Legend Stage-Master amplifier .
I have all the mosfets , transistors available at home , I have good quality 2200uF , 1000uF and 100uf capacitors .
My question to you it would be about the transformer size for two channel .
Please let me know what VA rating required . If I understood well these wold give close to 200W in 8 Ohm real power .
I'd like it because not much small transistors on the signal way.
Thanks
Greetings
After I finish the DoGC MK3 and if I will be satisfied(probably I will) I think I will build one more amplifier from your collection .
I would like to build the Legend Stage-Master amplifier .
I have all the mosfets , transistors available at home , I have good quality 2200uF , 1000uF and 100uf capacitors .
My question to you it would be about the transformer size for two channel .
Please let me know what VA rating required . If I understood well these wold give close to 200W in 8 Ohm real power .
I'd like it because not much small transistors on the signal way.
Thanks
Greetings
It is clearly stated on the very schematic that StageMaster is capable of healthy 250W on 8ohms and that was proven in several cases from people which built it already.
If you can, try to provide a transformer of at least 800VA if only one transformer will supply both channels. If that transformer is of a toroidal type, make sure that you have some kind of a soft-start due to significant inrush-current inherent with high power toroidals.
Of course, you can go even with 500VA but if you are planning prolonged and “heavy” usage (hours of operation on very high power) then you are likely to have frequent problems! In that case of a “hard labor” consider some kind of forced cooling even if you have substantial heatsinks.
If you can, try to provide a transformer of at least 800VA if only one transformer will supply both channels. If that transformer is of a toroidal type, make sure that you have some kind of a soft-start due to significant inrush-current inherent with high power toroidals.
Of course, you can go even with 500VA but if you are planning prolonged and “heavy” usage (hours of operation on very high power) then you are likely to have frequent problems! In that case of a “hard labor” consider some kind of forced cooling even if you have substantial heatsinks.