I'm totally agree with jmateus, this amp is very good (i build studio-se version), even i only build it with standart component. it's worth to build. It's sound very nice (nice bass, smooth treble, very detail). Picture taken a day before i finished my monoblock Amp.
Dr. Jagodic thank you for sharing this very good Amp.
Dr. Jagodic thank you for sharing this very good Amp.
Attachments
All the best about sound of this amplifier-not to complicated do be done,avaliable parts and realy realy great sound! You will think that somebody replaced your speakers for a pair of better one! I´ve assembled it last summer,but today it was painted and finished.
I´ve said it before and i will say it again:Thank you Borivoje!
I´ve said it before and i will say it again:Thank you Borivoje!
Attachments
Hello people! Thanks for the interesting read, and I'd like to extend gratitude from South Africa to Bora for making these designs available! I'm a beginner DIY audio enthusiast, all I've built so far is a valve guitar amp, but me and a friend have decided to build ourselves a Stereo Studio each . I'll most likely just use it for enjoyment of music for the moment, but I'd like to put together a home studio, so it will probably function as my first reference amplifier at some stage in the future!
A couple of questions I would love for you to entertain:
1st of all, what would be the best way to implement a volume control/attenuator for this amplifier? I doubt that I would ever run it at 85W per side as it stands and I would love to be able to have some control over the output.. Is it as simple as putting a voltage dividing variable resistor to ground on the front end? Basically reducing the input.
2nd, I realize its 85W into 8 ohms. I have a pair of 4 ohm studio monitor speakers that I'll be driving (for the meantime). Are there any special considerations that I would need to take into account? I understand that the output into 4 ohms would be 170W?
3rd, and this may relate to the second question, what sort of power supply circuit would be recommended? Would a simple linear supply be fine (ie just loads of big caps)? Or is a regulated supply necessary? I'll most likely be using a toroidal transformer, what VA and secondary voltages should I be looking at for a stereo version of this amp? The toroidal transformers available in SA generally have two pairs of secondaries, equal in output, ie 2 x 55-0, so I was thinking of doing a bridge rectifier from each secondary.
Thanks in advance and thanks again!
Jono
I'm a beginner DIY audio enthusiast, all I've built so far is a valve guitar amp, but me and a friend have decided to build ourselves a Stereo Studio each . I'll most likely just use it for enjoyment of music for the moment, but I'd like to put together a home studio, so it will probably function as my first reference amplifier at some stage in the future!A couple of questions I would love for you to entertain:
1st of all, what would be the best way to implement a volume control/attenuator for this amplifier? I doubt that I would ever run it at 85W per side as it stands and I would love to be able to have some control over the output.. Is it as simple as putting a voltage dividing variable resistor to ground on the front end? Basically reducing the input.
2nd, I realize its 85W into 8 ohms. I have a pair of 4 ohm studio monitor speakers that I'll be driving (for the meantime). Are there any special considerations that I would need to take into account? I understand that the output into 4 ohms would be 170W?
3rd, and this may relate to the second question, what sort of power supply circuit would be recommended? Would a simple linear supply be fine (ie just loads of big caps)? Or is a regulated supply necessary? I'll most likely be using a toroidal transformer, what VA and secondary voltages should I be looking at for a stereo version of this amp? The toroidal transformers available in SA generally have two pairs of secondaries, equal in output, ie 2 x 55-0, so I was thinking of doing a bridge rectifier from each secondary.
Thanks in advance and thanks again!
Jono
@1: if you have volume control on your preamplifier,that is all you need
@2: yes,it is 85W/8Ohm amplifier and it can go on 4Ohm load
but;the power will not be 170W,it will be arround 130W and with MJE21193/94 in output,2SC5200/2SA1943 are lower power transistors
but;than it will not have specs. as they are in :::Borina Amaterska Svastara::: ,and they are
Izlazna snaga---------85W RMS/8 oma
> Frekventni opseg-----4Hz-73KHz (pri 80-90% snage i izoblicenjima ispod 0.02%)
> THD-------------------<0.003% (20Hz-16KHz)... 0.008% na 20KHz
> TIM-------------------<0.002%
> Slew rate-------------50V/uS
> Damping faktor------->650
these specs. are given for a 8Ohm load.
@3; most people say that regulated supply "kills" dynamic characteristics of an amplifier,
i´ve done it without regulated supply and with some greate capacitors (69000uF per rail) and 250W transformer. Transformer should be much stronger for full amplifier characteristics on both channels,but in my way of using it this one does it enough. It is very good amplifier,specially in dynamic music it will show all that it has.
A few pistures how did people did it all around the world you can find here: Facebook
Good luck!
@2: yes,it is 85W/8Ohm amplifier and it can go on 4Ohm load
but;the power will not be 170W,it will be arround 130W and with MJE21193/94 in output,2SC5200/2SA1943 are lower power transistors
but;than it will not have specs. as they are in :::Borina Amaterska Svastara::: ,and they are
Izlazna snaga---------85W RMS/8 oma
> Frekventni opseg-----4Hz-73KHz (pri 80-90% snage i izoblicenjima ispod 0.02%)
> THD-------------------<0.003% (20Hz-16KHz)... 0.008% na 20KHz
> TIM-------------------<0.002%
> Slew rate-------------50V/uS
> Damping faktor------->650
these specs. are given for a 8Ohm load.
@3; most people say that regulated supply "kills" dynamic characteristics of an amplifier,
i´ve done it without regulated supply and with some greate capacitors (69000uF per rail) and 250W transformer. Transformer should be much stronger for full amplifier characteristics on both channels,but in my way of using it this one does it enough. It is very good amplifier,specially in dynamic music it will show all that it has.
A few pistures how did people did it all around the world you can find here: Facebook
Good luck!
Well, 44250 already addressed some of your dilemmas. For work on 4 ohms loads, amp will naturally try to produce much more power but it is very likely to blow out if you push it to more than about 50-60% of volume pot travel compared to 8 ohms operation. If you keep the same DC supply voltages, one pair of output devices will not survive full power on 4 ohms. Best option will be to reduce supply voltages to about +/-35V and to use 2SC3264/2SA1295 or 2SC3858/2SA1494 as output pair on a really GOOOOOD heatsink. Or keep original voltages but somehow limit your input signal so that amp is not producing more than it does on 8 ohms.
I don’t think you need stabilized supply if you provide decent transformer and at least 15-20.000uF per rail/per channel.
I don’t think you need stabilized supply if you provide decent transformer and at least 15-20.000uF per rail/per channel.
Thanks for the responses!
Ok bearing in mind what has been said about driving 4ohms speakers with this amp, I think that I will rather try to find some 8ohm monitors, or get another pair of the ones i have and put two in series on each channel.
I will go with a linear power supply, using two separate transformers (with two pairs of secondaries each), bridge rectifiers and filter caps. bearing in mind I want to have 2x 42 -0 and -42 -0 power rails, what V transformers should I be using? Is it just as simple as dividing 42V by 1.4? So that gives me 30V? What VA should I be looking at for each transformer? Would 200VA be enough?
Thanks again!
Jono
Ok bearing in mind what has been said about driving 4ohms speakers with this amp, I think that I will rather try to find some 8ohm monitors, or get another pair of the ones i have and put two in series on each channel.
I will go with a linear power supply, using two separate transformers (with two pairs of secondaries each), bridge rectifiers and filter caps. bearing in mind I want to have 2x 42 -0 and -42 -0 power rails, what V transformers should I be using? Is it just as simple as dividing 42V by 1.4? So that gives me 30V? What VA should I be looking at for each transformer? Would 200VA be enough?
Thanks again!
Jono
It would be 42 : 1,41 ~30Vac + 1,4V ~ 31,4Vac
this 1,4V is aded because that much will stay on a bridge rectifier (two diodes practically in series each with 0,7V).
200VA transformer per channel i beleive that would be just fine,and with 15 000uF per rail (if you can get that much) it would be a ultimate-machine!
Hi again,
Ok so I've started the planning stages with the excel spreadsheet. I have a couple of questions.. Firstly, on the circuit diagram, I'm not 100% sure of the resistor designations. I'm guessing 0E47 = 0.47ohms? I've seen it expressed as 0R47 before, but the E is throwing me off.
Second, would I really need 15000uF per RAIL, or per channel? if it were per rail I'd have 60,000uF! Is this right? Don't know how I'd fit them in the box.. Anyone have any suggestions as to filter caps you are prone to/prefer?
Thanks and regards,
Jono
Ok so I've started the planning stages with the excel spreadsheet. I have a couple of questions.. Firstly, on the circuit diagram, I'm not 100% sure of the resistor designations. I'm guessing 0E47 = 0.47ohms? I've seen it expressed as 0R47 before, but the E is throwing me off.
Second, would I really need 15000uF per RAIL, or per channel? if it were per rail I'd have 60,000uF! Is this right? Don't know how I'd fit them in the box.. Anyone have any suggestions as to filter caps you are prone to/prefer?
Thanks and regards,
Jono
Some prefer a sound of a first and some of a second version,i beleive that you will be very very satisfied with any of those two version. boraomega says that there should be about 2´000-3´000uF per rail behind every Amper that flows through loudspeaker,so if you have 150W in both channels,resistance of 8Ohm,P=R x I^2 ...
You got some answers already. If you use StudioSE PCB you can always turn it to orig. Studio with few simple mods but not vice versa. For full capabilities and specs you should have that much capacitance. That doesn't mean it will not work with 4700uF per rail but if you make both versions of PSU you will notice the difference clearly and easily.
My program for schematics and PCB generate letter E instead of R and that mean the same. 0E47 = 0R47 = 0,47ohms
My program for schematics and PCB generate letter E instead of R and that mean the same. 0E47 = 0R47 = 0,47ohms
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.