Jungson JA88-D(09) schematic.

[awkwardbydesign]

Does anyone have the schematic for the pre-amp section of this amp? Or know where I can find it?

[StanleyB]

Does anyone have the schematic for the pre-amp section of this amp? Or know where I can find it?
Check PM and don't ask how I got there ;).

[awkwardbydesign]

Still looking.

[tiguan]

You shall contact Troels Gravesen he uses the same at his workshop and plays with it as far as know. He probably have somewhere. http://www.troelsgravesen.dk/JungSon.htm

Troels.Gravesen@hotmail.com

[awkwardbydesign]

You shall contact Troels Gravesen he uses the same at his workshop and plays with it as far as know. He probably have somewhere. http://www.troelsgravesen.dk/JungSon.htm

Troels.Gravesen@hotmail.com
That was the first thing I did. He doesn't. And if you look at my signature, you will see that I have Troels Gravesen speakers!
I have already used his information to separate the pre and power sections of the amp, with a switch so I can use it as an integrated if I wish. I want to try different opamps in the RIAA section, but need more info first.

[tiguan]

Tapatalk don't show the signatures so I could not get, seems last chance producer itself.

[awkwardbydesign]

Tapatalk don't show the signatures so I could not get, seems last chance producer itself.

You need to get a proper computer! :lol:
I have sent Jungson an email; no reply yet.

[tiguan]

You need to get a proper computer! :lol:

For a mobile guy will be difficult :) :) one day, when I will be tired travelling I will think about...

[UV101]

I've got the full schematics for the JA88-D but its not the 09 version with the built in phono stage.

Not sure how similar the pre-amp section is.

What are you looking at? There is an input section that uses an opamp to covert single ended to balanced then its switched onto the discrete gain stage before going onto the relay controlled stepped attenuator.

I did a fair amount of work on mine when I had it so I may be able to help? :)

[awkwardbydesign]

I've got the full schematics for the JA88-D but its not the 09 version with the built in phono stage.

Not sure how similar the pre-amp section is.

What are you looking at? There is an input section that uses an opamp to covert single ended to balanced then its switched onto the discrete gain stage before going onto the relay controlled stepped attenuator.

I did a fair amount of work on mine when I had it so I may be able to help? :)

Thanks, but it's the phono stage I'm interested in! It uses a 5532 op amp, and I'm considering trying to replace it. Short of opening it up again, measuring the voltage on the + and - rails, and trying to sketch the circuit myself, I'm stuck. And I'd rather not do that if possible.
I bought it mainly for the power amp section ( http://www.troelsgravesen.dk/JungSon.htm ), but the pre isn't bad, so improving the sound* of the phono stage appeals.
* Thanks, but I don't need a discussion about the "adequacy" of the current set up.

[StanleyB]

Thanks, but it's the phono stage I'm interested in! It uses a 5532 op amp, and I'm considering trying to replace it. Short of opening it up again, measuring the voltage on the + and - rails, and trying to sketch the circuit myself, I'm stuck. And I'd rather not do that if possible.
Is that it? Why didn't you say mention that all along?
The 5532 is a standard dual type opamp. You can swap it over with a LM4562 ( I have loads of them somewhere), or a AD826. And that's just to name a few suitable opamps. Each one has its own sound signature.

[awkwardbydesign]

Is that it? Why didn't you say mention that all along?
The 5532 is a standard dual type opamp. You can swap it over with a LM4562 ( I have loads of them somewhere), or a AD826. And that's just to name a few suitable opamps. Each one has its own sound signature.
Because I wasn't expecting it to be so difficult! Anyway, thanks for the info. Someone on another forum already told me about the LM4562, but Farnell, who have them, have a £20 min order to avoid postage charges. And circuit details would tell me the rail voltage, which could matter, as some op amps perform differently at varying voltages. And whether it needs to be unity gain stable. Also I like to learn as much as possible anyway.
EDIT- I see Farnell have the AD826 as well, so 2 of each is getting me close to the £20. I probably need some more caps and resistors for the TT spark suppressors I'm making up, so that would take me over the £20.

[StanleyB]

Because I wasn't expecting it to be so difficult! Anyway, thanks for the info. Someone on another forum already told me about the LM4562, but Farnell, who have them, have a £20 min order to avoid postage charges. And circuit details would tell me the rail voltage, which could matter, as some op amps perform differently at varying voltages. And whether it needs to be unity gain stable. Also I like to learn as much as possible anyway.
EDIT- I see Farnell have the AD826 as well, so 2 of each is getting me close to the £20. I probably need some more caps and resistors for the TT spark suppressors I'm making up, so that would take me over the £20.
The rail voltage won't tell you anything about the final performance. The only way to know what the performance will be is to actually hear the amp play after you have made the changes.

I suggest that you fit the opamps in a DIL-8 socket so that you can swap opamps around and listen to each of them in order to make your mind up which ones you prefer. The AD826 will give a more bass orientated and warmer sound. The LM4562 tends to be a bit more flat. It can sound kind of sharp in the wrong circuit application. The Benchmark HDR-1 is an example of where the LM4562 should not have been used IMHO.

PM me your address and I'll have a look over the festive period what my opamp trays got in them that might be useful to try. Just let me know how many opamps are used in the circuit. And don't forget to fit some DIL-8 sockets on the PCB so that you can swap opamsp over and listen to the sound!

For caps, use WIMA where possible where electrolytics are not required. I find that they give a far more open sound.

[Light Dependant Resistor]

Because I wasn't expecting it to be so difficult! Anyway, thanks for the info. Someone on another forum already told me about the LM4562, but Farnell, who have them, have a £20 min order to avoid postage charges. And circuit details would tell me the rail voltage, which could matter, as some op amps perform differently at varying voltages. And whether it needs to be unity gain stable. Also I like to learn as much as possible anyway.
EDIT- I see Farnell have the AD826 as well, so 2 of each is getting me close to the £20. I probably need some more caps and resistors for the TT spark suppressors I'm making up, so that would take me over the £20.

Hi Richard
The LM4562 would be the pick of the bunch, basically anything extra you are hearing is not the op amp contributing. AD826 also very nice but starts having a sound of its own unlike the LM4562 that is just honest with its presentation. The rail voltage ideally should be 15volts + and 15 volts - , and if capacitive loads are being driven with the 4562 resistors of about 75 ohms between each channel of the op amp output and those capacitors assists better performance.
I have stock of some SOIC 4562 and will have to check stock of brown dog adapters but if I have some can also place surface mount resistors for you, so you just plug them in - if DIP turned pin sockets are fitted.

Cheers / Chris

[awkwardbydesign]

The rail voltage won't tell you anything about the final performance. The only way to know what the performance will be is to actually hear the amp play after you have made the changes.

I suggest that you fit the opamps in a DIL-8 socket so that you can swap opamps around and listen to each of them in order to make your mind up which ones you prefer. The AD826 will give a more bass orientated and warmer sound. The LM4562 tends to be a bit more flat. It can sound kind of sharp in the wrong circuit application. The Benchmark HDR-1 is an example of where the LM4562 should not have been used IMHO.

PM me your address and I'll have a look over the festive period what my opamp trays got in them that might be useful to try. Just let me know how many opamps are used in the circuit. And don't forget to fit some DIL-8 sockets on the PCB so that you can swap opamsp over and listen to the sound!

For caps, use WIMA where possible where electrolytics are not required. I find that they give a far more open sound.
Thanks, I'll PM you. I only need 2, and there are sockets on the board already, otherwise I probably wouldn't bother. The amp was bought for the power amp section, bur I figured if I could get the phono stage sounding as I liked it, it would be more versatile. My wife complained that if anything happened to me, she wouldn't be able to operate the stereo! And she has a point; my last bike crash was rather unpleasant. So an amp that will do everything without needing a phono stage or pre-amp would be handy. Just in case I die, y'know! At the moment I am using Chris's LDR pre, and very nice it is too.
The rail voltage might be significant if it was too far from +/- 15v, as I believe some op amps don't like too low or high voltages.

Hi Richard
The LM4562 would be the pick of the bunch, basically anything extra you are hearing is not the op amp contributing. AD826 also very nice but starts having a sound of its own unlike the LM4562 that is just honest with its presentation. The rail voltage ideally should be 15volts + and 15 volts - , and if capacitive loads are being driven with the 4562 resistors of about 75 ohms between each channel of the op amp output and those capacitors assists better performance.
I have stock of some SOIC 4562 and will have to check stock of brown dog adapters but if I have some can also place surface mount resistors for you, so you just plug them in - if DIP turned pin sockets are fitted.

Cheers / Chris
Hi Chris, I was originally considering AD825s, as the ones you used to supply me with sounded better in the active crossover. But of course a phono stage is a bit different, and as I don't have the schematic I don't know how different. As you know I am no expert, so I need to play it safe. The existing sockets look like turned pin.
http://i1134.photobucket.com/albums/m604/awkwardbydesign/Mobile%20Uploads/2014-12/bfe9ed3b-2713-4170-b29f-78e886f5fd31_zps93174e2a.jpg (http://s1134.photobucket.com/user/awkwardbydesign/media/Mobile%20Uploads/2014-12/bfe9ed3b-2713-4170-b29f-78e886f5fd31_zps93174e2a.jpg.html)

[Light Dependant Resistor]

Thanks, I'll PM you. I only need 2, and there are sockets on the board already, otherwise I probably wouldn't bother. The amp was bought for the power amp section, bur I figured if I could get the phono stage sounding as I liked it, it would be more versatile. My wife complained that if anything happened to me, she wouldn't be able to operate the stereo! And she has a point; my last bike crash was rather unpleasant. So an amp that will do everything without needing a phono stage or pre-amp would be handy. Just in case I die, y'know! At the moment I am using Chris's LDR pre, and very nice it is too.
The rail voltage might be significant if it was too far from +/- 15v, as I believe some op amps don't like too low or high voltages.

Hi Chris, I was originally considering AD825s, as the ones you used to supply me with sounded better in the active crossover. But of course a phono stage is a bit different, and as I don't have the schematic I don't know how different. As you know I am no expert, so I need to play it safe. The existing sockets look like turned pin.
http://i1134.photobucket.com/albums/m604/awkwardbydesign/Mobile%20Uploads/2014-12/bfe9ed3b-2713-4170-b29f-78e886f5fd31_zps93174e2a.jpg (http://s1134.photobucket.com/user/awkwardbydesign/media/Mobile%20Uploads/2014-12/bfe9ed3b-2713-4170-b29f-78e886f5fd31_zps93174e2a.jpg.html)

Hi Richard
I have some DIP size ( same as the 5532 size ) LM4562, so can send you one. I also have dual type brown dog adapters but will need to get in some LM49710 singles to do the 75 ohm surface mount resistors. Can you PM or email me the schematic that Stanley B kindly located, I can then assess if the DIP size is suitable.

Changing the op amp is very easy as the turned pin socket is there, turn power off on the Jungson & remove its power cord. The best tool is a proper IC extraction one, but with a small jewelers screwdriver gently lever a bit from each end, the 5532 will start coming up, try to have it even or flat as it leaves the socket that way pins will not bend and it can be used again in another circuit. I will send you a LM4562 already in a turned pin adapter as they can be a bit tricky going back in.

Pin 1 is the round circle on the 5532, and the socket I send I will mark pin 1 for you

Cheers / Chris

[awkwardbydesign]

Hi Richard
I have some DIP size ( same as the 5532 size ) LM4562, so can send you one. I also have dual type brown dog adapters but will need to get in some LM49710 singles to do the 75 ohm surface mount resistors. Can you PM or email me the schematic that Stanley B kindly located, I can then assess if the DIP size is suitable.

Changing the op amp is very easy as the turned pin socket is there, turn power off on the Jungson & remove its power cord. The best tool is a proper IC extraction one, but with a small jewelers screwdriver gently lever a bit from each end, the 5532 will start coming up, try to have it even or flat as it leaves the socket that way pins will not bend and it can be used again in another circuit. I will send you a LM4562 already in a turned pin adapter as they can be a bit tricky going back in.

Pin 1 is the round circle on the 5532, and the socket I send I will mark pin 1 for you

Cheers / Chris

Thanks again Chris. I have some tools for mounting and demounting ICs; after all, I have done enough of them, I think 36 in the active crossover!
http://images.maplinmedia.co.uk/ic-insertion-tool.jpg?w=283&h=283&r=4&o=AMKhNekgoNI3Rv@wCWoOt5hGXfsj&V=X8Jchttp://images.maplinmedia.co.uk/ic-extraction-tool.jpg?w=283&h=283&r=4&o=gevqEmvwPL21f42VbE714$6k6R8j&V=No$a
Unfortunately, the schematic Stan located is only for the power amp, which is what I already had. And he is going to root out a couple of LM4562s for me. Aren't they a drop in replacement for the NE5532s without an adapter anyway?

[Light Dependant Resistor]

Hi Richard
Yes they are generally drop in replacements. My comments about the 75 ohm resistors refers to page 23 of the datasheet that states
" The LM4562 is a high-speed op amp with excellent phase margin and stability. Capacitive loads up to 100pF will
cause little change in the phase characteristics of the amplifiers and are therefore allowable.
Capacitive loads greater than 100pF must be isolated from the output. The most straightforward way to do this is
to put a resistor in series with the output. This resistor will also prevent excess power dissipation if the output is
accidentally shorted."

So if you have more than 100pf without a resistor between that capacitor and the outputs that are on Pin 1 and Pin 7 a small resistor is advisable


this gives meaning to using two single LME49710 on a Brown dog adapter and to fit surface mount resistors on each output, then again there may already be a resistor or no capacitive load
hence asking for the schematic to check this for you.

Cheers / Chris

[awkwardbydesign]

Hi Richard
Yes they are generally drop in replacements. My comments about the 75 ohm resistors refers to page 23 of the datasheet that states
" The LM4562 is a high-speed op amp with excellent phase margin and stability. Capacitive loads up to 100pF will
cause little change in the phase characteristics of the amplifiers and are therefore allowable.
Capacitive loads greater than 100pF must be isolated from the output. The most straightforward way to do this is
to put a resistor in series with the output. This resistor will also prevent excess power dissipation if the output is
accidentally shorted."

So if you have more than 100pf without a resistor between that capacitor and the outputs that are on Pin 1 and Pin 7 a small resistor is advisable


this gives meaning to using two single LME49710 on a Brown dog adapter and to fit surface mount resistors on each output, then again there may already be a resistor or no capacitive load
hence asking for the schematic to check this for you.

Cheers / Chris

Ah, now I understand. Unfortunately I've had no luck with the schematic; Jungson haven't responded to my email, maybe they never will. I will, of course, let you know if I find out. I will try to follow the circuit when I open up the amp next time, but I won't risk demounting the board. The new wiring I added to separate the pre and power sections caused me enough problems, trying to get it all in!