Wow! According to the diagrams the output caps are inside the feedback loop!:xeye Now I need to consult my old theory books on this one. The problem is that increasing the the value of the output caps effectively improves the frequency response at the lower end but those lower frequencies are now being passed back as negative feedback. I'm just concerned that phase shifts aren't turning negative feedback into positive feedback. I could do with some help on this one if anyone knows better than me!
Does it sound ok? You might need to feed in a 1kHz signal and examine the output.
That output circuit looks finely tuned to me. Take a look at R125/C111 and C113/R126. That's manipulating the frequency response and is done to make sure negative feedback stays negative at all times.
Maybe you deserve a medal if all those changes you have done work and the only issue you had were with the grounding. So how about that then! You've taken a classic amp and improved it! I might follow your example!😀
Does it sound ok? You might need to feed in a 1kHz signal and examine the output.
That output circuit looks finely tuned to me. Take a look at R125/C111 and C113/R126. That's manipulating the frequency response and is done to make sure negative feedback stays negative at all times.
Maybe you deserve a medal if all those changes you have done work and the only issue you had were with the grounding. So how about that then! You've taken a classic amp and improved it! I might follow your example!😀
You'll be lucky Andy, if it isnt mega watt monoblocks with heatsinks the size of bread bins there not interested!😀
Interesting point about the 4 x feedback 0.1 film caps and R's, I havent got a scope so its pure guesswork if its making poss feedback, Doesnt distort or overheat so cant be that much wrong, Just fitted a thermistor to deal with the start up inrush and a mains noise filter just for the hell of it, Next the good qual caps now its stable.
I like the open, warm sound of the thing, Might not be exiting to everyone but I use transmission line speaks, says alot about me I suppose?
252's have loads of potential for modders...Even though purists might disagree?🙄
Nai let me know what ye find with this feedback theorum Mr K dude!😉
Interesting point about the 4 x feedback 0.1 film caps and R's, I havent got a scope so its pure guesswork if its making poss feedback, Doesnt distort or overheat so cant be that much wrong, Just fitted a thermistor to deal with the start up inrush and a mains noise filter just for the hell of it, Next the good qual caps now its stable.
I like the open, warm sound of the thing, Might not be exiting to everyone but I use transmission line speaks, says alot about me I suppose?
252's have loads of potential for modders...Even though purists might disagree?🙄
Nai let me know what ye find with this feedback theorum Mr K dude!😉
Well I might not go as far as you did but I've got a confession to make. I too bought the 252 on ebay BUT not knowing it at the time mine was an active system so I've got 2 amplifiers. One like yours and the other more akin to a power amp. So, I'm going to butcher one of them pretty much like you did.
Purists make me yawn anyway, what you've done to yours is technically correct and sounds better. So what's so un-pure about that?
Strange thing is that I've got tranmission line loudspeakers as well and yes, I agree, the amp sounds 'warm'. I like it!
😀
Purists make me yawn anyway, what you've done to yours is technically correct and sounds better. So what's so un-pure about that?
Strange thing is that I've got tranmission line loudspeakers as well and yes, I agree, the amp sounds 'warm'. I like it!
😀
We must become the 252 transmission brothers.... Could I offer you my meat cleaver, Mr kayne?😀
Mines really come to life now, It great!
Very undervalued piece of ye olde british Hi'fi wouldnt you say!
Should be more info on the intranerd! There again...... be another nad 3020 mish cyrus scenario! They fight like tooth and nail!
Mines really come to life now, It great!
Very undervalued piece of ye olde british Hi'fi wouldnt you say!
Should be more info on the intranerd! There again...... be another nad 3020 mish cyrus scenario! They fight like tooth and nail!
No magic.
R125/C111 is just an output zobel network and R126 provides a ground/ unload for the output capacity. Otherwise, when you plug in your speakers in the powered-on amp, your woofers will possibly blow. This resistor also forms an "end" to the feedback loop.
To include the cap in the NFB loop is clever and well implemented - the loop includes another elcap of course and the compensation. This amp would not work any other way.
I often wonder why (relatively small!) output caps are so underrated sonically. They can provide a very often necessary bass compensation which makes many speakers have much better bass. Numerous tiny loudspeakers do actually incorporate those caps to form a highpass (!) bass correction. This shifts the parameters into a much more workable range.
R125/C111 is just an output zobel network and R126 provides a ground/ unload for the output capacity. Otherwise, when you plug in your speakers in the powered-on amp, your woofers will possibly blow. This resistor also forms an "end" to the feedback loop.
To include the cap in the NFB loop is clever and well implemented - the loop includes another elcap of course and the compensation. This amp would not work any other way.
I often wonder why (relatively small!) output caps are so underrated sonically. They can provide a very often necessary bass compensation which makes many speakers have much better bass. Numerous tiny loudspeakers do actually incorporate those caps to form a highpass (!) bass correction. This shifts the parameters into a much more workable range.
Hi Iohk!
Over the weekend I filled it up with Elna Silmics, they seem to work well with the nytech, Much more soild and robust sound stage, As an experiment, I upped the coupling caps to 330uf.......Made all the difference... so there staying, Seem to have taken the slight edge off the tweeters too!
Just got to get rid of the horrible ceramics now with poly or orange drops, then put everything in 2 black granite, allu, with maybe a copper frontage cases! separate psu... Prob overkill... But might as well make it look as good as it sounds!
Andy did you get a chance to take pics?🙂
Over the weekend I filled it up with Elna Silmics, they seem to work well with the nytech, Much more soild and robust sound stage, As an experiment, I upped the coupling caps to 330uf.......Made all the difference... so there staying, Seem to have taken the slight edge off the tweeters too!
Just got to get rid of the horrible ceramics now with poly or orange drops, then put everything in 2 black granite, allu, with maybe a copper frontage cases! separate psu... Prob overkill... But might as well make it look as good as it sounds!
Andy did you get a chance to take pics?🙂
Hi All
Got side tracked this weekend but will get around to taking some photos for you.
Interesting comments made about this output cap. I'm going to replace them for bigger ones and see if it makes a difference. Some amps have them, some don't, some include them in the feedback loop and some don't. lohk is hinting that the circuit design of this amp is quite accomplished and the more I look at it the more I'm thinking that it is. Ok it's manufacture is not classic but the circuit may be.
Interesting thing is that I couldn't buy the Nytech 23 years ago coz I was skint but I eventually bought an amp from a different manufacturer instead which I've just found in the garage with blown ouput trannies but I will get it fixed and compare them. It' got output caps as well!
It's such a major component to have in the signal path compared to a directly coupled amplifier that it surely must make a difference to the way a amplifier sounds. Any thoughts?
Got side tracked this weekend but will get around to taking some photos for you.
Interesting comments made about this output cap. I'm going to replace them for bigger ones and see if it makes a difference. Some amps have them, some don't, some include them in the feedback loop and some don't. lohk is hinting that the circuit design of this amp is quite accomplished and the more I look at it the more I'm thinking that it is. Ok it's manufacture is not classic but the circuit may be.
Interesting thing is that I couldn't buy the Nytech 23 years ago coz I was skint but I eventually bought an amp from a different manufacturer instead which I've just found in the garage with blown ouput trannies but I will get it fixed and compare them. It' got output caps as well!
It's such a major component to have in the signal path compared to a directly coupled amplifier that it surely must make a difference to the way a amplifier sounds. Any thoughts?
Yeah, most current thoughts seem to go away from electroylics esp in the signal path, These old amps come from more of a romantic era where the ethos was, if it felt right, is was, take kef bextrene drivers for example, on paper not good, but they still have a huge cult following, People are way too wrapped up in figures and graphs these days, But the upsurgence back to valve amps and turrntables speak differently!
Richard Hey knew his stuff, But the layout of the amp left alot to be desired, Who would place a mains on/off switch right next to the input switches these days? Or pack it in such a small unventilated case, As soon as I opened it up, instantly I knew there were obvious easilly rectified short comings.
Computers in my mind have taken away some of the magic in amplifier design, After all its subjective and down to personal Preference hence the interest in retro hi fi as opposed to clinical and in some cases boring cad amps made in their millions.
This is a great forum, no question!!! But I get disheartened by the endless figures, topologies and theologies...Its about music pure and simple, The saddest thing is a person sitting alone on a whicker chair in an unfurnished room surrounded by expensive perfectly matched Equipment wondering if the 'produced' cymbals on his BBC mastered recording sound slightly harsh!...Ive been there and its a lonely place.............Once the obsession takes over...its time to stop!
Rant over!
😀
Richard Hey knew his stuff, But the layout of the amp left alot to be desired, Who would place a mains on/off switch right next to the input switches these days? Or pack it in such a small unventilated case, As soon as I opened it up, instantly I knew there were obvious easilly rectified short comings.
Computers in my mind have taken away some of the magic in amplifier design, After all its subjective and down to personal Preference hence the interest in retro hi fi as opposed to clinical and in some cases boring cad amps made in their millions.
This is a great forum, no question!!! But I get disheartened by the endless figures, topologies and theologies...Its about music pure and simple, The saddest thing is a person sitting alone on a whicker chair in an unfurnished room surrounded by expensive perfectly matched Equipment wondering if the 'produced' cymbals on his BBC mastered recording sound slightly harsh!...Ive been there and its a lonely place.............Once the obsession takes over...its time to stop!
Rant over!
😀
Well said...
my CA202 is from ~1983...
https://fotoalbum.web.de/gast/cr.4y/Nytech
Maybe it is not the best amp ever...but in its day it´s bang for the buck!
BTW: take a look @
http://www.divdev.fsnet.co.uk/repair5.htm
...scroll down...some Serviceinformation is available.
Carsten
my CA202 is from ~1983...
https://fotoalbum.web.de/gast/cr.4y/Nytech
Maybe it is not the best amp ever...but in its day it´s bang for the buck!
BTW: take a look @
http://www.divdev.fsnet.co.uk/repair5.htm
...scroll down...some Serviceinformation is available.
Carsten
I was thinking about this the other day and wondering whether to say something or not. Whilst amps do sound different and even I can hear that it's got be be down to the differences in design. I mean look at circuit diagrams and they are like chalk and cheese at the end of the day.
Nothing wrong with sound engineering principles to make it more reliable and upgrading components because you can. I mean, what's all this about cables that have arrows on them? Does that mean that the cable has to be connected only one way around?
Recordings, by the time they are pressed onto CD's have been through 100's of op-amps, filters, cables, plugs etc etc.
Tonight, I'm going to sit down, relax and enjoy my Nytech without worrying whether the cymbals sound right or not and besides, how do you know what the orignal master reording sounds like anyway?🙂
PS. I just might have to get up once in a while to bash it on the side then the right hand channel channel fades out due to that dodgey switch.🙄
Nothing wrong with sound engineering principles to make it more reliable and upgrading components because you can. I mean, what's all this about cables that have arrows on them? Does that mean that the cable has to be connected only one way around?
Recordings, by the time they are pressed onto CD's have been through 100's of op-amps, filters, cables, plugs etc etc.
Tonight, I'm going to sit down, relax and enjoy my Nytech without worrying whether the cymbals sound right or not and besides, how do you know what the orignal master reording sounds like anyway?🙂
PS. I just might have to get up once in a while to bash it on the side then the right hand channel channel fades out due to that dodgey switch.🙄
He'he'he'he!😀
Wires have directions ye know Andy!🙄 You must solder them in the correct orientation,
I like the "whats the best resistor thread!"😀
one of the funniest is someone saying the best upgrade is to get your ears syringed!!!
Its a hobby a passion, But you have to know when to cry enough!
At least no one mentiones Ri**er So**ds and W**t H* F*!!😀
Andy m8......I have the switches!😱 Mine were in good nick as I recal?!?!?! if you need them!
Please excuse me.....
I'm now going to order gold plated everything on line............
Wires have directions ye know Andy!🙄 You must solder them in the correct orientation,
I like the "whats the best resistor thread!"😀
one of the funniest is someone saying the best upgrade is to get your ears syringed!!!
Its a hobby a passion, But you have to know when to cry enough!
At least no one mentiones Ri**er So**ds and W**t H* F*!!😀
Andy m8......I have the switches!😱 Mine were in good nick as I recal?!?!?! if you need them!
Please excuse me.....
I'm now going to order gold plated everything on line............
schematics nytech ca 252
Hello, does anyone got the schematics and could email me ?
Would highly appraciet it.
per(AT)ekstrom(DOT).cc
Hello, does anyone got the schematics and could email me ?
Would highly appraciet it.
per(AT)ekstrom(DOT).cc
Word of caution, if your doing any work on these amps, use a solder wick, DONT USE A SOLDER SUCKER/ PUMP, the PCB tracks esp on the main amp boards are glued with wallpaper paste and delaminate really easilly, Mine got to the stage with the various mods, changes that they were all but knackered.I'm in the process of P2P ATM..why not AAARG!
Nytech
Wow. Theres a name from the past. I designed the original Injection Mould tools for the calculator shaped Nytech, Thats going back a long time. I was chief designer for a company called Jacy Plastics then. We did not have any CAD / CAM then and it was quite a tricky mould design then. Would have been a piece of cake now days and I would have had the moulds manufactured in China as I do now.
I cant remember the guys name who was behind the Nytech company, he was often at the factory and we would run through the design problems. He was a nice man as I remember. I wonder what he is up to now.
Patrick.
Wow. Theres a name from the past. I designed the original Injection Mould tools for the calculator shaped Nytech, Thats going back a long time. I was chief designer for a company called Jacy Plastics then. We did not have any CAD / CAM then and it was quite a tricky mould design then. Would have been a piece of cake now days and I would have had the moulds manufactured in China as I do now.
I cant remember the guys name who was behind the Nytech company, he was often at the factory and we would run through the design problems. He was a nice man as I remember. I wonder what he is up to now.
Patrick.
Richard Hey, changping, He's still about, Think he's involved with Heed audio now, not too sure???😉
Who has overtaken Nytech ?
The old address I read on the schematic from line pre amp unit:
NYTECH AUDIO LTD
HIGH STREET
CHEW MAGNA
BRISTOL BS18 (BS40) 8PW 01332959 027589-3232 (027689-0232)
On page 9 about
http://www.sydneyaudioclub.org.au/FEEDBACK 1_3 May 2008.pdf
I read the name "David Cooper". He worked for Nytech Audio in Bristol from 1978 until 1979. Who knows this person?
Here an additional interesting URL
http://www.gramophone.net/Issue/Page/February 1977/113/863411/
BTW, "Richard Hay" and "David Alner" are listed by the topic "The Best Audio Engineers" about
http://www.pinkfishmedia.net/forum/showthread.php?t=27155
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