I cannot construct things...my daugther made me promisse
But i am crazy to tweak the old GEM amplifier, the third one i construct from Graham Maynard.
This one has incredible sound.... seems that you have a hole into your wall and in the other room there's an orchestra playing...incredible presence....but this one has a lot of bugs...noises and circuit problems.
Graham made this one only in the computer and he did not aprove this one even during simulations.....hehe...if i was simulator fanatic i would never had listened to this one.
regards,
Carlos
But i am crazy to tweak the old GEM amplifier, the third one i construct from Graham Maynard.
This one has incredible sound.... seems that you have a hole into your wall and in the other room there's an orchestra playing...incredible presence....but this one has a lot of bugs...noises and circuit problems.
Graham made this one only in the computer and he did not aprove this one even during simulations.....hehe...if i was simulator fanatic i would never had listened to this one.
regards,
Carlos
This one is from John Ellis.... not the last one, as he made another update.
This is first John Ellis published in this thread.
hehe...i think John produce those schematics at a ratio of 5 each day.
And people say that i am crazy...not only me!....Graham produce many schematics each day too...and now a days he is spending part of the day boiling watter to obtain a good bath for birds that visit him in the cold Ireland.
Do not tell people...Graham may not apreciate...but the water turns ice and he goes and substitute the water once more...ahahahahahah!
Lovely and sweet man.... a half crazy also.
regards,
Carlos
This is first John Ellis published in this thread.
hehe...i think John produce those schematics at a ratio of 5 each day.
And people say that i am crazy...not only me!....Graham produce many schematics each day too...and now a days he is spending part of the day boiling watter to obtain a good bath for birds that visit him in the cold Ireland.
Do not tell people...Graham may not apreciate...but the water turns ice and he goes and substitute the water once more...ahahahahahah!
Lovely and sweet man.... a half crazy also.
regards,
Carlos
Some schematics are so dificult to reproduce to a layout that you'll
find yourself in a maze of lines and pads that dworf your capacity of
thinking and doing whatever else you need to complete it.
Carlos has his way of doing things, I do my boards (not so complicated)
the same way, but often times I have to give up due to the complication of the design. The problem is, doing the layout by this
not very inteligent method the board ends up with a lot of mistakes
that are very hard sometimes to rectify. Because it is an empirical
method it doesn't have anything rational nor scientific except the
obvious.
I do my boards that way and most times I feel myself thinking
this is so stupid that is not even funny! But I continue to do it (the
not so difficult ones) because , first I don't want to buy a layout program to do the layouts, second, because I must be very lazy to
learn the free ones. I tried a few and none is easy, besides they all deal with double layer or multi layer and I don't want to do double boards, just single layers.
I wish there was a program in which you just had to do a click on the computer and....pronto, the board is done, no there isn't!
So, this is the story Jerry, most people must be bored to death by these thoughts but I figured that someone would have at least
some curiosity. I'm done, boards are boards anyway, very
rarely they contribute to your hapiness......
find yourself in a maze of lines and pads that dworf your capacity of
thinking and doing whatever else you need to complete it.
Carlos has his way of doing things, I do my boards (not so complicated)
the same way, but often times I have to give up due to the complication of the design. The problem is, doing the layout by this
not very inteligent method the board ends up with a lot of mistakes
that are very hard sometimes to rectify. Because it is an empirical
method it doesn't have anything rational nor scientific except the
obvious.
I do my boards that way and most times I feel myself thinking
this is so stupid that is not even funny! But I continue to do it (the
not so difficult ones) because , first I don't want to buy a layout program to do the layouts, second, because I must be very lazy to
learn the free ones. I tried a few and none is easy, besides they all deal with double layer or multi layer and I don't want to do double boards, just single layers.
I wish there was a program in which you just had to do a click on the computer and....pronto, the board is done, no there isn't!
So, this is the story Jerry, most people must be bored to death by these thoughts but I figured that someone would have at least
some curiosity. I'm done, boards are boards anyway, very
rarely they contribute to your hapiness......
New thread is here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=95021
Yell out if you want a different title.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=95021
Yell out if you want a different title.
Hi all
destroyer X has posted that the JLH-update he built (at lightning speed) needed some mods to work with his 2SC5200 outputs.
I'm not surprised, simulations showed that the circuit was not so hot with fast outputs.
I've tested the "flipped" version of the circuit posted (NPN inputs, PNP VAS) and it seems to be fine.
Image shows a (pretty poor) photo of clipping with amp running from 35V rails at 20 kHz with MJ15003/4 output pair. "Noise" in the clipping parts is not oscillation - just poor regulation from the power supply.
I'm working on a mod for fast outputs.
Will post if that works. So far seems to give good simulation results even for quasi (OK for BDY56's? Sorry, no can do for 2N3442!)
cheers
John
destroyer X has posted that the JLH-update he built (at lightning speed) needed some mods to work with his 2SC5200 outputs.
I'm not surprised, simulations showed that the circuit was not so hot with fast outputs.
I've tested the "flipped" version of the circuit posted (NPN inputs, PNP VAS) and it seems to be fine.
Image shows a (pretty poor) photo of clipping with amp running from 35V rails at 20 kHz with MJ15003/4 output pair. "Noise" in the clipping parts is not oscillation - just poor regulation from the power supply.
I'm working on a mod for fast outputs.
Will post if that works. So far seems to give good simulation results even for quasi (OK for BDY56's? Sorry, no can do for 2N3442!)cheers
John
Attachments
Hi all
Trickier to develop the fast-output version of the JLH update ciruit, but have a working solution.
Choices of the output configuration! With the "sprog stopper" capacitors C9, C3 in the circuit below, it is possible to connect the stabilisation capacitor C8 either as JLH originally placed it between the VAS and base of the feedback side of the input stage, or as I have shown as a "deferred" Miller.
The deferred Miller capacitor was suggested by Cherry to improve distortion. Simulating the three options (a) as JLH connected it (b) as I have shown and (c) as a true Miller shows that (a) and (c) have similiar crossover distortion but (b) is lower.
Version (a) shows some spikes on a square wave test, so seems to be slightly less stable. You can try different options but the method shown seems to be giving the lowest audible distortion (overall distortion figures are slightly higher than the Miller, but audible distortions are lower).
Measured performance gives about 300 kHz bandwidth with the 3 uH choke, without input filter capacitor.
cheers
John
Trickier to develop the fast-output version of the JLH update ciruit, but have a working solution.
Choices of the output configuration! With the "sprog stopper" capacitors C9, C3 in the circuit below, it is possible to connect the stabilisation capacitor C8 either as JLH originally placed it between the VAS and base of the feedback side of the input stage, or as I have shown as a "deferred" Miller.
The deferred Miller capacitor was suggested by Cherry to improve distortion. Simulating the three options (a) as JLH connected it (b) as I have shown and (c) as a true Miller shows that (a) and (c) have similiar crossover distortion but (b) is lower.
Version (a) shows some spikes on a square wave test, so seems to be slightly less stable. You can try different options but the method shown seems to be giving the lowest audible distortion (overall distortion figures are slightly higher than the Miller, but audible distortions are lower).
Measured performance gives about 300 kHz bandwidth with the 3 uH choke, without input filter capacitor.
cheers
John
Attachments
Hi all
The JLH FastMod update for quasi.
The BDY56 spec was 10 MHz for fT, so although I do not have a model for this, perhaps it will work in this circuit as is.
The MJL3281A's are faster, but maybe anyone with a stash of BDY56's could try this one.
Crossover distortion is not unduly worse than in the comlementary version
because of the compensation capacitor which is taken from the output, not the collector of the VAS. As originally proposed by Cherry.
cheers
John
The JLH FastMod update for quasi.
The BDY56 spec was 10 MHz for fT, so although I do not have a model for this, perhaps it will work in this circuit as is.
The MJL3281A's are faster, but maybe anyone with a stash of BDY56's could try this one.
Crossover distortion is not unduly worse than in the comlementary version
because of the compensation capacitor which is taken from the output, not the collector of the VAS. As originally proposed by Cherry. cheers
John
Hello John,
In this thread you designed several updates for the JLH-amplifier. The last version of the previous post 93 is about the JLH FastMod update for quasi. This is a direct coupled version.
I have made the original version with output capacitor and asymmetrical supply (+ 27V with capacitance multiplier) a long time ago. From what I understand from theory is that the output capacitor ( in my case a BHC with a nice MKP in parallel) is not that bad because with a symmetrical design the supply capacitors are also part of the signal path. This way I do not need a protection circuit for my loudspeakers.
I would like to experiment with your last update, given my existing asymmetrical power supply. I think – as a non-EE - your design can be used but would need an adaption to set the output to half the supply voltage. Is that correct? Can you please indicate what I would need to change in your update for the quasi design?
As this thread is about the direct coupled version maybe you can send me a pm. I could also start a new thread when there would be more interest to experiment with the asymmetrical version.
Best, Arjen.
In this thread you designed several updates for the JLH-amplifier. The last version of the previous post 93 is about the JLH FastMod update for quasi. This is a direct coupled version.
I have made the original version with output capacitor and asymmetrical supply (+ 27V with capacitance multiplier) a long time ago. From what I understand from theory is that the output capacitor ( in my case a BHC with a nice MKP in parallel) is not that bad because with a symmetrical design the supply capacitors are also part of the signal path. This way I do not need a protection circuit for my loudspeakers.
I would like to experiment with your last update, given my existing asymmetrical power supply. I think – as a non-EE - your design can be used but would need an adaption to set the output to half the supply voltage. Is that correct? Can you please indicate what I would need to change in your update for the quasi design?
As this thread is about the direct coupled version maybe you can send me a pm. I could also start a new thread when there would be more interest to experiment with the asymmetrical version.
Best, Arjen.
javascript:smilie('')Hi guys
I have just had my cyrus two start playing up after many years of faithful service. The board version is ver 7 on Cyrus two.
I started getting buzzing noises from my gorgeous phono stage that these amps have. And suspected the Power Caps need replaceing. Ive taken amp only at present apart and found the caps to be C65 C66, C67 and C68. with polarity marked on the board.
javascript:smilie('
') I contacted Cyrus with a view to buying replacements, and schematics, but they have emailed me back and said "Sorry company policy, cant send out parts or schematic but are happy for me to ship the amp to them for them to charge me £149 + Shipping, Going on the weight of these things alone would probably bankrupt me
Can anyone help here. where can I get replacements from, and do I need to replace all the little caps as well or just these main 4,
regards
mark
')Hi guysI have just had my cyrus two start playing up after many years of faithful service. The board version is ver 7 on Cyrus two.
I started getting buzzing noises from my gorgeous phono stage that these amps have. And suspected the Power Caps need replaceing. Ive taken amp only at present apart and found the caps to be C65 C66, C67 and C68. with polarity marked on the board.
javascript:smilie('
') I contacted Cyrus with a view to buying replacements, and schematics, but they have emailed me back and said "Sorry company policy, cant send out parts or schematic but are happy for me to ship the amp to them for them to charge me £149 + Shipping, Going on the weight of these things alone would probably bankrupt meCan anyone help here. where can I get replacements from, and do I need to replace all the little caps as well or just these main 4,
regards
mark
in your situation of try it and hear, you may be changing the wrong components.
The main smoothing caps are likely to be the culprit, but take some measurements to be sure.
The non-electrolytic capacitors do not age like the the electrolytics.
BTW,
there are a number of Cyrus threads. Ask for this to be moved.
The main smoothing caps are likely to be the culprit, but take some measurements to be sure.
The non-electrolytic capacitors do not age like the the electrolytics.
BTW,
there are a number of Cyrus threads. Ask for this to be moved.
Ref Cyrus Two Noisy amp
Many thanks Andrew,
The Caps listed in my last post are the Two main Smoothing Capacitors 50V 10,000uf and I think the preamp caps 63V 470 uf I suspect as you do that These are the main problem, They are after all now over 15 - 20 years old.
I would like to replace them as a matter of course. I should have taken some measurements before I disconnected the board, which means that I have to reseat the Power Transistors on the heat sink again, so will change these first.
This is my second post, im a newbee and would appreciate advice on how I go about moving these two posts to the Cyrus threads.
Its a long time since Ive dabbled in this field, and having to remind myself a lot of procedures but its starting to come back and is quite relaxing.
Would I be correct in measuring the caps with my scope to detect ac ripple breakthrough, I presume it would show ripple if leaky, ampitude depending on leakage.
Thanks in advance for your help and advice
Regards
Mark
Many thanks Andrew,
The Caps listed in my last post are the Two main Smoothing Capacitors 50V 10,000uf and I think the preamp caps 63V 470 uf I suspect as you do that These are the main problem, They are after all now over 15 - 20 years old.
I would like to replace them as a matter of course. I should have taken some measurements before I disconnected the board, which means that I have to reseat the Power Transistors on the heat sink again, so will change these first.
This is my second post, im a newbee and would appreciate advice on how I go about moving these two posts to the Cyrus threads.
Its a long time since Ive dabbled in this field, and having to remind myself a lot of procedures but its starting to come back and is quite relaxing.
Would I be correct in measuring the caps with my scope to detect ac ripple breakthrough, I presume it would show ripple if leaky, ampitude depending on leakage.
Thanks in advance for your help and advice
Regards
Mark
It's been a long time since I've done anything with audio but during a cap and trimpot replacement I unfortunately let the smoke out of one channel of my old LJH 75W / DC Coupled Amp. Mine was a powertran version, some components differ from the version on Geoff's site, my schematic is here.
I can't find BDY56's and I also need to replace the BD529/530's which are suffering some kind of leadframe rot and fall off their legs at the slightest touch.
Can you help me with some suggested currently available and affaordable transistors that I can use as replacements? By available I mean from e.g Mouser, Digi-Key, Newark, or some vendor you can name.
TO3 would be nice for the outputs, but adapting to plastic parts wouldn't be difficult.
(P.S. I see this amp has generated some emotion in the past. I only ever used the power amp which sounded good at the time, 1977, and now my ears are too old to tell the difference. I hated the preamp and never used it.)
I can't find BDY56's and I also need to replace the BD529/530's which are suffering some kind of leadframe rot and fall off their legs at the slightest touch.
Can you help me with some suggested currently available and affaordable transistors that I can use as replacements? By available I mean from e.g Mouser, Digi-Key, Newark, or some vendor you can name.
TO3 would be nice for the outputs, but adapting to plastic parts wouldn't be difficult.
(P.S. I see this amp has generated some emotion in the past. I only ever used the power amp which sounded good at the time, 1977, and now my ears are too old to tell the difference. I hated the preamp and never used it.)
I have an amp made in 1975 based on the JLH 75W circuit using 2N3055 or 2N3442's. The one I have has been fiddled with, and the transistors changed, but someone sent me the Powertran kit from 1976 that looks as if it was the base on which my fiddles version was made from. Is there a kind soul who can help improve it, as my 2014 rebuild is overheating, largely due (I THINK) to equivalents not being good ones, or a least 2nd or 3rd level equivalents by now. I will mail both circuits to interested parties, or send me more into on the Powertran kit
Much thanks
Joy - my first post here !
Much thanks
Joy - my first post here !
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.