Couple of questions
Hi All,
I am hoping Promitheus or one of the other veterans of this project can step in and advise me, or even some of the other builders if they still frequent the board.
First the Transformer. What would be a realistic specification for one that would supply both channels?
I found one here that looks interesting...
http://www.amplimo.nl/ go to Standard Range on menu and Last on the page
toroidal transformer 80VA 2x 30V Part no 38017
Is that too big? and is it really better to use two small transformers instead.
Second question regarding the Pearl input R1. As I am building the MC stage and will use a Med output cartridge (0.8) what should I fit in the R1 position, should it be a standard 47K?
And Finally...
Are the plastic insulators under the Heatsinks at Q1 critical? If they are where can they be bought?
Any help appreciated
Hi All,
I am hoping Promitheus or one of the other veterans of this project can step in and advise me, or even some of the other builders if they still frequent the board.
First the Transformer. What would be a realistic specification for one that would supply both channels?
I found one here that looks interesting...
http://www.amplimo.nl/ go to Standard Range on menu and Last on the page
toroidal transformer 80VA 2x 30V Part no 38017
Is that too big? and is it really better to use two small transformers instead.
Second question regarding the Pearl input R1. As I am building the MC stage and will use a Med output cartridge (0.8) what should I fit in the R1 position, should it be a standard 47K?
And Finally...
Are the plastic insulators under the Heatsinks at Q1 critical? If they are where can they be bought?
Any help appreciated
Non-standard toroidal
I also have a transformer question. In Australia I can source a 12VAC toroidal but not 15V. Would this be a problem if I used it? See: http://tinyurl.com/65hg6b
There is a 15V option but it is not as well shielded. See: http://tinyurl.com/6aqlcz
Alabama978 said:
I also have a transformer question. In Australia I can source a 12VAC toroidal but not 15V. Would this be a problem if I used it? See: http://tinyurl.com/65hg6b
There is a 15V option but it is not as well shielded. See: http://tinyurl.com/6aqlcz
Transformer
Hi AJ,
Sorry that nobody has answered your questions.
I have build two versions of the NP Pearl + ONO MC as supplied by Promitheus.
One is using a 2 x 30V, 80 VA and one 2 x 30V, 50VA.
Following my proposal:
1. If you intent to install the PSU in a separate box you can use the 80VA but also the 50 VA type.
2. In the case you install the PSU in the same box as the Pearl it would be advisable to use the 50VA to lower the risk for noise pick up.
OK?
Rgds
Gerd
Hi AJ,
Sorry that nobody has answered your questions.
I have build two versions of the NP Pearl + ONO MC as supplied by Promitheus.
One is using a 2 x 30V, 80 VA and one 2 x 30V, 50VA.
Following my proposal:
1. If you intent to install the PSU in a separate box you can use the 80VA but also the 50 VA type.
2. In the case you install the PSU in the same box as the Pearl it would be advisable to use the 50VA to lower the risk for noise pick up.
OK?
Rgds
Gerd
Hi Gerd,
Thank you for your informative reply. I have considered building all into one nice 19 inch case and putting a metal divider between the PSU section and the phono stages but it is a concern that it may pick up hum especially since I am building the MC stage too.
jacco vermeulen....
Dank U Val,
WYNI.... and go back and read the thread before spouting off accusations
You will see that I have bought the complete MC and Pearl kit. What I referred to in the post you quoted was a version produced in Asia and sold on Ebay with most of the Jfets missing.
I cannot understand your last sentence (what is a stealIY gene) but in English throwing up can mean to vomit
I am sure you don't want to do that on this nice friendly board.
Thank you for your informative reply. I have considered building all into one nice 19 inch case and putting a metal divider between the PSU section and the phono stages but it is a concern that it may pick up hum especially since I am building the MC stage too.
jacco vermeulen....
Dank U Val,
WYNI.... and go back and read the thread before spouting off accusations
You will see that I have bought the complete MC and Pearl kit. What I referred to in the post you quoted was a version produced in Asia and sold on Ebay with most of the Jfets missing.
I cannot understand your last sentence (what is a stealIY gene) but in English throwing up can mean to vomit
I am sure you don't want to do that on this nice friendly board.
Thought I may come in here with a question, since this is the most active pearl thread
I've been enjoying my peal for quite a few months, but am getting the tweak bug !
Currently, there is a large 10uF capacitor on the output. Now as I'm using it to drive something with a large input impedence (about 100k), I figured a smaller value (such as 0.47, or even 0.22 uF) would suffice.
Anyone tried this ? Any other particular reason why this output cap is so massive ?
I've been enjoying my peal for quite a few months, but am getting the tweak bug !
Currently, there is a large 10uF capacitor on the output. Now as I'm using it to drive something with a large input impedence (about 100k), I figured a smaller value (such as 0.47, or even 0.22 uF) would suffice.
Anyone tried this ? Any other particular reason why this output cap is so massive ?
Capacitor C9 - Mundorf 10 uf
I can't answer your question about which value is best for your system however I have a question about this capacitor supplied in the Group buy...
I am a little concerned that my capacitors made my Mundorf are marked as 5% tolerance, and all others I have seen sold by Mundorf are 3%
Will this affect the performance? Are these capacitors a special purchase at 5% and if so why?
Can anyone who has bought the kit confirm the tolerance on their Mundorfs?
I do not want to fit them especially the 10uf output caps on the phono stage board (C9) if they are not to specification.
I can't answer your question about which value is best for your system however I have a question about this capacitor supplied in the Group buy...
I am a little concerned that my capacitors made my Mundorf are marked as 5% tolerance, and all others I have seen sold by Mundorf are 3%
Will this affect the performance? Are these capacitors a special purchase at 5% and if so why?
Can anyone who has bought the kit confirm the tolerance on their Mundorfs?
I do not want to fit them especially the 10uf output caps on the phono stage board (C9) if they are not to specification.
Mundorf Caps
@lordvader, Alabama,
First, the non-symetric circuit produce a high DC offset at the output, thus the high value of 10uF is required to eliminate about 19V DC offset.
But the exact value (+/- 5%) isn't of importance.
The NP original design use even electrolytic caps with 110uF value.
But I would not recommend to use lower values than the 10uF to prevent any DC off set at the entrance of the following station.
Clear?
Rgds.
Gerd
@lordvader, Alabama,
First, the non-symetric circuit produce a high DC offset at the output, thus the high value of 10uF is required to eliminate about 19V DC offset.
But the exact value (+/- 5%) isn't of importance.
The NP original design use even electrolytic caps with 110uF value.
But I would not recommend to use lower values than the 10uF to prevent any DC off set at the entrance of the following station.
Clear?
Rgds.
Gerd
More questions this time on Gain
I am still building both the MC and Pearl stages but have one question for any members who can help regarding total gain and how to adjust it.
My amp requires a figure of around 66 db input to produce the same output level as the CD stage. Reading the schematics I see that I can add both JP1 and JP2 to the MC board and reduce the total gain to 16dB
Add to the Pearl and I then have 16 + 60 = 76dB which seems way too much but then I am not an electronics guru
What would be the best way to match the output of my 800Uv Benz Ace cartridge to the amp? Can I change values of the resistors R17, R18, or R21 on the MC stage.
Am I on the wrong track?
I am still building both the MC and Pearl stages but have one question for any members who can help regarding total gain and how to adjust it.
My amp requires a figure of around 66 db input to produce the same output level as the CD stage. Reading the schematics I see that I can add both JP1 and JP2 to the MC board and reduce the total gain to 16dB
Add to the Pearl and I then have 16 + 60 = 76dB which seems way too much but then I am not an electronics guru
What would be the best way to match the output of my 800Uv Benz Ace cartridge to the amp? Can I change values of the resistors R17, R18, or R21 on the MC stage.
Am I on the wrong track?
If you have Hi output MC cartridge you can connect it to MM stage. On the MM board you can solder resistor Rx. This resistor will adjust the input impedance according to the recomended value for your cartridge (Benz ACE works fine with 250 Ohms up to 1K). Pearl MM stage will perform fine in this mode.
High output
Hi Smario,
Thanks for the reply. I could certainly do this but as I bought the MC kit and may eventually move to a LO cart I want to keep it more flexible and use the MC stage too.
The problem is that the Benz Ace Med is 800 uV so in between LO and HO making it harder to match without under/overdriving I think.
Hi Smario,
Thanks for the reply. I could certainly do this but as I bought the MC kit and may eventually move to a LO cart I want to keep it more flexible and use the MC stage too.
The problem is that the Benz Ace Med is 800 uV so in between LO and HO making it harder to match without under/overdriving I think.
I connected Denon DL103, Benz ACE medium output and Lyra Helikon to MM input and it worked without problems. If you buy low output cartridge, then you should use MC stage. I also use MC stage with Benz ACE low output and it works fine on lowest gain setting. I suggest that you leave the original design and try to connect your ACE to MM stage. I think that you will have enough gain even without MC stage. When you buy low output MC cartridge, then you just switch to MC mode.
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