Hi all, I'm trying to build a preamplifier that use the line
stage of Thorsten Loesh toccata clone ( I've seen the project on "thunderstoneaudio", http://www.fortunecity.com/rivendell/xentar/1179/projects/toccata/Toccata.html ) but I've some problems.
I've used only one 5687, just to try the circuit...for the heaters
no problem, I've changed the resistor in the lm317 circuit from
2.7Ohm to 1.35Ohm in order to have 0.9A on the output. And it
works. The problem is the At circuit. I've used 0.68uF arcotronics
1.44 400V instead of the 0.47uF arcotronics 1.72 and a 55VA Isolation transformer. I have not found the D1N750 so I have tried with a 5W 4.7V zener (BZV58C4V7); these are the only differences from the original layout. Today I have tried to turn it on; without the load the
output voltage is about 260V but when I connected the power on the circuit the voltage went down to 40V!!! To adjust the trimmer makes no difference.
The tension on the last capacitor in front of the mosfet circuit was
about 330/350V.
The line stage seems to work however: before realizing that the
voltage in the line stage was only 40V I connected it with the
system and, even if with lots of distortions, the signal came out.
However, I will try the circuit with a simpler powersupply in order
to be sure that it will work. As regards the "amplified capacitor" Circuit, what do you think I have to check? Is it so sensitive to the current draw? I don't think so but I can't understand why it doesn't work under load. I've checked the pcb that I built, and it does not seem to have mistakes.
Sorry for my bad English.Thanks in advance.
Mark
stage of Thorsten Loesh toccata clone ( I've seen the project on "thunderstoneaudio", http://www.fortunecity.com/rivendell/xentar/1179/projects/toccata/Toccata.html ) but I've some problems.
I've used only one 5687, just to try the circuit...for the heaters
no problem, I've changed the resistor in the lm317 circuit from
2.7Ohm to 1.35Ohm in order to have 0.9A on the output. And it
works. The problem is the At circuit. I've used 0.68uF arcotronics
1.44 400V instead of the 0.47uF arcotronics 1.72 and a 55VA Isolation transformer. I have not found the D1N750 so I have tried with a 5W 4.7V zener (BZV58C4V7); these are the only differences from the original layout. Today I have tried to turn it on; without the load the
output voltage is about 260V but when I connected the power on the circuit the voltage went down to 40V!!! To adjust the trimmer makes no difference.
The tension on the last capacitor in front of the mosfet circuit was
about 330/350V.
The line stage seems to work however: before realizing that the
voltage in the line stage was only 40V I connected it with the
system and, even if with lots of distortions, the signal came out.
However, I will try the circuit with a simpler powersupply in order
to be sure that it will work. As regards the "amplified capacitor" Circuit, what do you think I have to check? Is it so sensitive to the current draw? I don't think so but I can't understand why it doesn't work under load. I've checked the pcb that I built, and it does not seem to have mistakes.
Sorry for my bad English.Thanks in advance.
Mark
Hi,
I would have expected the HT prior to the FET to drop because of the voltage then lost over the choke, so if the regulator circuit isn't performing then the first suspest has to be the change of diode. What is a 1N750? Is this also a 4.7v zener?
I would have expected the HT prior to the FET to drop because of the voltage then lost over the choke, so if the regulator circuit isn't performing then the first suspest has to be the change of diode. What is a 1N750? Is this also a 4.7v zener?
bobhayes said:
I think so...well I'm not sure, I didn't find the datasheet, but the shopkeeper told me so. Where can I find the datascheet?
Loesch
Hello,
try to change the Zener into something between 12 and 20 Volts. Maybe your Fet needs a little more gate voltage. It is only a protection diode to prevent that gate/source voltage is to high.
Can you measure the voltage before the Fet, also down?
If not, try the other zener
Reinhard
Hello,
try to change the Zener into something between 12 and 20 Volts. Maybe your Fet needs a little more gate voltage. It is only a protection diode to prevent that gate/source voltage is to high.
Can you measure the voltage before the Fet, also down?
If not, try the other zener
Reinhard
Re: Loesch
Hi Reinhard, thankyou for the replay
I mesure the voltage on the last capacitor under load. I've read something about 330V. Do you mean this voltage? Or the one in front of the fet, between drain and ground? 😕
Mark
reinhard said:
Hi Reinhard, thankyou for the replay
I mesure the voltage on the last capacitor under load. I've read something about 330V. Do you mean this voltage? Or the one in front of the fet, between drain and ground? 😕
Mark
Konnichiwa,
The Zenner Diode is part of the protection circuit. It needs to be selected in value to match the FET's Turnon Voltage (varies quite widely for individual samples of the same type FET). What you are getting is that the circuit limits the current at too low a current, so use a Zenner Diode one or two voltage ratings up from 4.7V.
Sayonara
mark_titano said:
The Zenner Diode is part of the protection circuit. It needs to be selected in value to match the FET's Turnon Voltage (varies quite widely for individual samples of the same type FET). What you are getting is that the circuit limits the current at too low a current, so use a Zenner Diode one or two voltage ratings up from 4.7V.
Sayonara
Ok! Thankyou very much for the replay Thorsten! Today I'll buy some zener...10V-15V-20V and I'll try them friday, when I will come back home...what do you think about power dissipation? 5W or 1/2W?
Mark
Mark
Konnichiwa,
The Zenner Diode only operates in a fault condition and the current passed is very limited. I usually use the small glass case ones, I think 1/4 Watt. If you increase the voltage too much you remove the short circuit protection this diode affords. Unless you know the treshold voltage for the current drawn by the linestage you should adjust the voltage up in small steps, so try 5.6V & 6.8V next.
Sayonara
mark_titano said:
The Zenner Diode only operates in a fault condition and the current passed is very limited. I usually use the small glass case ones, I think 1/4 Watt. If you increase the voltage too much you remove the short circuit protection this diode affords. Unless you know the treshold voltage for the current drawn by the linestage you should adjust the voltage up in small steps, so try 5.6V & 6.8V next.
Sayonara
Ok, I'll try first 5.6V and 6.8 V.
Do you think that I can try this circuit for higher current? I want to build a small power amp that use a sep of el84. I'll need again 250V so I'm thinking to use this Zero loop-feedback Regulator with an RC or LC combo of it's output. Can you help me to find some good articles that explains how does it works?
Thanks
Mark
Do you think that I can try this circuit for higher current? I want to build a small power amp that use a sep of el84. I'll need again 250V so I'm thinking to use this Zero loop-feedback Regulator with an RC or LC combo of it's output. Can you help me to find some good articles that explains how does it works?
Thanks
Mark
Konnichiwa,
Correctly set up and with sufficient cooling - sure. I am often using this in commercial amplifier modifications where chokes and extra cap's are not too easy to fit.
Sayonara
mark_titano said:
Correctly set up and with sufficient cooling - sure. I am often using this in commercial amplifier modifications where chokes and extra cap's are not too easy to fit.
Sayonara
It's working! I have to use a 9.1V zener to have 250V...
I'm looking around to find a good electronic manual to understand how the circuit work ( to use it with other circuits).
Suggestions?
Thorsten...thankyou very much!
I have some other questions: which is the operating point for the 5687 ( for the toccata)? I have 250V before of the last RC network but I don't know which is the corrected tension (current) on the valve. If, in the original project, the current draw for one channel is 35mA I think the voltage drop is only about 1.5V on the 47ohm resistor...I'm right? What I have to check?
The grid battery must be a rechargeable type? I'm using normal lithium cell...
At the moment I don't use the 39kOhm into 22kOhm Voltage Divider for the CD-Player input. I'd better use it?
I'm using Ero 1845 to the input ( 0.1uF 1600V) and Arcotronics 1.70 to the output ( 2.5uF 400v). For the last Rc network I'm using a parallel of a standard electrolytic capacitor (elna 47uF 450V) with an arcotronics 1.44 ( 0.68uF 400V).
The volume control is a 10K alps stereo.
What's about it? I'm too far from the right sound?
However, the pre seems to me "something special"...😀
I can't speak english so good to review it, but what I can say is that it is the better pre I've ever listen. My last project was a 6sn7 srpp...nothing in common. Toccata line stage have more bass and an incredible stereo imeges. The sound is cleaner and more precise. For me, however, the best quality is the sense of rhythm.
I hope you can understand what I said
Mark
I'm looking around to find a good electronic manual to understand how the circuit work ( to use it with other circuits).
Suggestions?
Thorsten...thankyou very much!
I have some other questions: which is the operating point for the 5687 ( for the toccata)? I have 250V before of the last RC network but I don't know which is the corrected tension (current) on the valve. If, in the original project, the current draw for one channel is 35mA I think the voltage drop is only about 1.5V on the 47ohm resistor...I'm right? What I have to check?
The grid battery must be a rechargeable type? I'm using normal lithium cell...
At the moment I don't use the 39kOhm into 22kOhm Voltage Divider for the CD-Player input. I'd better use it?
I'm using Ero 1845 to the input ( 0.1uF 1600V) and Arcotronics 1.70 to the output ( 2.5uF 400v). For the last Rc network I'm using a parallel of a standard electrolytic capacitor (elna 47uF 450V) with an arcotronics 1.44 ( 0.68uF 400V).
The volume control is a 10K alps stereo.
What's about it? I'm too far from the right sound?
However, the pre seems to me "something special"...😀
I can't speak english so good to review it, but what I can say is that it is the better pre I've ever listen. My last project was a 6sn7 srpp...nothing in common. Toccata line stage have more bass and an incredible stereo imeges. The sound is cleaner and more precise. For me, however, the best quality is the sense of rhythm.
I hope you can understand what I said
Mark
Konnichiwa,
Can't remember exactly, I seem to remember it was around 90V, but don't shout at me if I'm wrong....
No, lithium button cells are just fine.
Remember, there is no "right sound". I can tell you what I do and like, but the ultimate arbiter of what you like is you, not me.
Sayonara
mark_titano said:
Can't remember exactly, I seem to remember it was around 90V, but don't shout at me if I'm wrong....
mark_titano said:
No, lithium button cells are just fine.
mark_titano said:
Remember, there is no "right sound". I can tell you what I do and like, but the ultimate arbiter of what you like is you, not me.
Sayonara
Kuei Yang Wang said:
Not at all!!! You've been so kind...😉
I'll see the datasheet and try to find a fine operation point
Kuei Yang Wang said:
Good
Kuei Yang Wang said:
I completely agree with you. What I tried to understand was which components , in your opinion, could improve the sound. All resistor are Allen Bradley and the Ero 1845 seems to me good.
I've never try before Arcotronics 1.70, a friend told me that is good. Here the data sheet
http://www.arcotronics.it/download.php?id=8
What I'll change first of all will be the electrolytic capacitor on the last rc network. I'll try solen cap, I can find it more easily than Ansar supersound.
Thankyou, again. 🙂
Mark
Well in this two days, I've listened the preamp a lot... I think there's something wrong. Bass and middle bass are perfects.
Vertical and horizontal image are very good, so the stability of the image in these directions.
What I find not good are the highs and the deep of the sound stage. I can't describe what I feel. It seems, sometimes, dark. Flat...there's no sense of depth, no air around the speakers.
I try fist to change the output capacitor with two CCCP paper in oil. The result is the same one , something better in the middle but nothing else.
Maybe the problem could these one:
1) operation point: it seems to me that the pre sound better when it's just turned on.
2) I'm waiting for the 10k vishay anode resistor, I've bought it on web...now I use a simply 5W ceramic resistor. Maybe too inductive?
3) something wrong in the power supply? Now it seems to work, the output voltage is 250V. I don't already change the last capacitors, I'm waiting for the solen fast cap...
Hola
Mark
Vertical and horizontal image are very good, so the stability of the image in these directions.
What I find not good are the highs and the deep of the sound stage. I can't describe what I feel. It seems, sometimes, dark. Flat...there's no sense of depth, no air around the speakers.
I try fist to change the output capacitor with two CCCP paper in oil. The result is the same one , something better in the middle but nothing else.
Maybe the problem could these one:
1) operation point: it seems to me that the pre sound better when it's just turned on.
2) I'm waiting for the 10k vishay anode resistor, I've bought it on web...now I use a simply 5W ceramic resistor. Maybe too inductive?
3) something wrong in the power supply? Now it seems to work, the output voltage is 250V. I don't already change the last capacitors, I'm waiting for the solen fast cap...
Hola
Mark
Konnichiwa,
It is hard to be cartain what causes this. Notes of what I use in the specific positions:
1) Input Coupling Capacitor is 62nF/100V Tinfoil & Polystyrene in Yellow (old surplus, I bought them ages back by the kilogram, best low value cap I have ever found), I would suspect silver mica may work well there too.
2) ICW MKP (aka ICW "ClarityCap" but mine where from before that rather cynical audiophile branding policy) with multiple bypass as per steinmusic, that is 0.52uF ERO KP1832, 0.075uF ERO KP1832, 3600pF ERO KP1832, NFS Styroflex 2700pF, Lemo Silver Mica 2200pF.
3) Anode resistor is Painton noninductive wirewound, endcapless construction with solid silver leadouts, military surplus.
4) Volume Control is GEC/Plessy Type 72 32-Position rotary switch, 4-Deck with Holco (old nonmagnetic type) ladder attenuator.
5) Powersupply Ansar Supersound MKP, bypassed as the output coupling capacitor.
Looking at your part lineup you substituted very poor quality parts in all places, compared to those I use. I was thinking you used them because you liked the way they sound. You will find it next to impossible obtaining what I used.
So try the following:
Input and Output Coupling -> M-Cap Zn
Volume Control -> Discrete resistor ladder attenuator, Dale resistors RC55 standard types
Powersupply -> good quality MKP, please avoid Solen/SCR Metalised capaictors if you can
Sayonara
mark_titano said:
It is hard to be cartain what causes this. Notes of what I use in the specific positions:
1) Input Coupling Capacitor is 62nF/100V Tinfoil & Polystyrene in Yellow (old surplus, I bought them ages back by the kilogram, best low value cap I have ever found), I would suspect silver mica may work well there too.
2) ICW MKP (aka ICW "ClarityCap" but mine where from before that rather cynical audiophile branding policy) with multiple bypass as per steinmusic, that is 0.52uF ERO KP1832, 0.075uF ERO KP1832, 3600pF ERO KP1832, NFS Styroflex 2700pF, Lemo Silver Mica 2200pF.
3) Anode resistor is Painton noninductive wirewound, endcapless construction with solid silver leadouts, military surplus.
4) Volume Control is GEC/Plessy Type 72 32-Position rotary switch, 4-Deck with Holco (old nonmagnetic type) ladder attenuator.
5) Powersupply Ansar Supersound MKP, bypassed as the output coupling capacitor.
Looking at your part lineup you substituted very poor quality parts in all places, compared to those I use. I was thinking you used them because you liked the way they sound. You will find it next to impossible obtaining what I used.
So try the following:
Input and Output Coupling -> M-Cap Zn
Volume Control -> Discrete resistor ladder attenuator, Dale resistors RC55 standard types
Powersupply -> good quality MKP, please avoid Solen/SCR Metalised capaictors if you can
Sayonara
Mhmm...very interesting approach Thorsten.
I'm not very expert, at all...I start to built tube amp and pre only two years ago. I've much to learn!
This is very interesting tip off...I'll try do something like this.
There are some reason for each value? I've got at home arcotronics 0.015uF and 1500pF KP72, ero 1813 0.47uF...I'll do some test 😉
I'm waiting for vishay and some kiwame...all the resistors, except
the anode one, are Allen Bradley.
In this moment this is a solution too expensive for my budget. I'm reading about the ladder volume control of aleph pre series. I want to build something similar.
So in the last rc network there is an Ansar Supersound MKP with multiple bypass like 0.52uF ERO KP1832, 0.075uF ERO KP1832, 3600pF ERO KP1832, NFS Styroflex 2700pF, Lemo Silver Mica 2200pF!!?? Well, never listen someting like this! Call me FAN 😀!
I'll try someting like this
Honestly , I have some problems with the budget...
I'm trying to find some better components, but with the prices in the market I can't afford to buy all the special components you used in your implementation.
Mhmm...avoid the Solen. Ok...
i can find easily Audin Cap Qs, Solen and Digitex (from 30uF to 200uF 400/600V Mkp). Digitex are made by Icel, some friend tell me they are good. For the input and output coupling I can try with MIT multicap film and thin foil or with TRT infinicap...other option could be the audin cap plus. This is what I can find easily.
Thankyou... 🙂
Mark
I'm not very expert, at all...I start to built tube amp and pre only two years ago. I've much to learn!
Kuei Yang Wang said:
This is very interesting tip off...I'll try do something like this.
There are some reason for each value? I've got at home arcotronics 0.015uF and 1500pF KP72, ero 1813 0.47uF...I'll do some test 😉
Kuei Yang Wang said:
I'm waiting for vishay and some kiwame...all the resistors, except
the anode one, are Allen Bradley.
Kuei Yang Wang said:
In this moment this is a solution too expensive for my budget. I'm reading about the ladder volume control of aleph pre series. I want to build something similar.
Kuei Yang Wang said:
So in the last rc network there is an Ansar Supersound MKP with multiple bypass like 0.52uF ERO KP1832, 0.075uF ERO KP1832, 3600pF ERO KP1832, NFS Styroflex 2700pF, Lemo Silver Mica 2200pF!!?? Well, never listen someting like this! Call me FAN 😀!
I'll try someting like this
Kuei Yang Wang said:
Honestly , I have some problems with the budget...
I'm trying to find some better components, but with the prices in the market I can't afford to buy all the special components you used in your implementation.Kuei Yang Wang said:
Mhmm...avoid the Solen. Ok...
i can find easily Audin Cap Qs, Solen and Digitex (from 30uF to 200uF 400/600V Mkp). Digitex are made by Icel, some friend tell me they are good. For the input and output coupling I can try with MIT multicap film and thin foil or with TRT infinicap...other option could be the audin cap plus. This is what I can find easily.
Thankyou... 🙂
Mark
Kuei Yang Wang said:
I find this...
http://cgi.ebay.it/ws/eBayISAPI.dll?ViewItem&category=14993&item=5729146823&rd=1
and...
http://www.olimpiaudio.com/Listini/Mundorf.html
For the mundorf... there is a great difference between ZN, supreme and silver foil?
Mark
a la steinmusic
Hello Thorsten,
Andy Grove from Audio Note once told us: Paralled caps sound like "cat****". use ONE good cap.
Reinhard
Hello Thorsten,
Andy Grove from Audio Note once told us: Paralled caps sound like "cat****". use ONE good cap.
Reinhard
- Status
- Not open for further replies.