Received my board today, it is printed V9 now.
A quick question, I have a 120V/12-0-12/2A trafo instead of 13-0-13. I measured at the 13-0-13 power terminals and got only 11.8V as my main was only at 118V. Since the LM317 needs at least 3VDC between the input and the output. Is this too marginal? As of now, it is playing and seems to be pretty quiet.
A quick question, I have a 120V/12-0-12/2A trafo instead of 13-0-13. I measured at the 13-0-13 power terminals and got only 11.8V as my main was only at 118V. Since the LM317 needs at least 3VDC between the input and the output. Is this too marginal? As of now, it is playing and seems to be pretty quiet.
Well after the recrifier you should get around 16.5V on LM317/337 inputs so that should be OK.
Also there should be a variable resistor by the LM317 so you can lower the output voltage, the opamps won't mind, but I don't think it's necessary..
Well i found this post here: from gerarda but the build looks quite ruff.
I also found this one here by ch33ta *link*
This is looking better, but usually you need 2 trannies for the dac right?
Ch33ta, maybe you can post the values of the parts? Didnt find that yet.
I will use an extra board for the trannies and put all parts on that board. that will look a bit cleaner
I also found this posts here and here, they describe the built of gerarda
I also found this one here by ch33ta *link*
This is looking better, but usually you need 2 trannies for the dac right?
Ch33ta, maybe you can post the values of the parts? Didnt find that yet.
I will use an extra board for the trannies and put all parts on that board. that will look a bit cleaner
I also found this posts here and here, they describe the built of gerarda
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ch33ta pic is with just one transformer connected for show/testing purpose I think.
gerada has his in a seperate box is all.
He states how he has connected them:
Here is a picture of my monacor implementation.
Input from DAC (before capacitors at L+/-, R+/-) through series resistors of 220 Ohm to connection 1 and 3.
In between 1 and 3 a capacitor of about 7 nF. (4,7 + 1,8 in my case).
From 6 and 8 to the output with a resistor of 1k and cap of 3nF between 6 and 8
The 7nf cap he has across 1 & 3 after the 220 ohm resistors on the primary, and the 1k and 3nf cap in series across 6 & 8 on the secondary.
gerada has his in a seperate box is all.
He states how he has connected them:
Here is a picture of my monacor implementation.
Input from DAC (before capacitors at L+/-, R+/-) through series resistors of 220 Ohm to connection 1 and 3.
In between 1 and 3 a capacitor of about 7 nF. (4,7 + 1,8 in my case).
From 6 and 8 to the output with a resistor of 1k and cap of 3nF between 6 and 8
The 7nf cap he has across 1 & 3 after the 220 ohm resistors on the primary, and the 1k and 3nf cap in series across 6 & 8 on the secondary.
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Yes, I only got one Monacor for testing purposes only, of course you need two of those...
As for the filter I started with Jensen filter, not that exact values but pretty close, capacitors were the same value, the resistors were 250R and 1k...
Although, you can start with no filter, just resistors in series on DAC output and see how it sounds... Worked pretty good with my Monacor, but the sound was better with the filter, highs settled a bit...
As far as i know it's important to put the secondary filter to filter out HF noise because some people had problems with amplifiers oscillating because of that...
As for the filter I started with Jensen filter, not that exact values but pretty close, capacitors were the same value, the resistors were 250R and 1k...
Although, you can start with no filter, just resistors in series on DAC output and see how it sounds... Worked pretty good with my Monacor, but the sound was better with the filter, highs settled a bit...
As far as i know it's important to put the secondary filter to filter out HF noise because some people had problems with amplifiers oscillating because of that...
here you go, I have just used the values in that discription - I think by that diagram 1 goes to 6 and 3 to 8, so if you connect 1 to the dac's R+(positive) 6 goes to the positive on the RCA and like wise the 3 is connected to the R- (negative) output leg of the dac and 8 to the negative of the RCA.
Attachments
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some posts ago I wrote about my experience with the JC-2 preamp, following the output trannies.
But, after reading the links and more about the B1 preamp, eg. a JFET source follower with a constant current source, I think, that this is more suitable to follow a 1:1 trannie, because it's gain is about unity.
So, I built up a B1 with 2SK289 and the split rail psu based on LM317. 10uF MKP at the outputs, bypassed by sowjet caps.
I will try this circuit soon.
Franz
But, after reading the links and more about the B1 preamp, eg. a JFET source follower with a constant current source, I think, that this is more suitable to follow a 1:1 trannie, because it's gain is about unity.
So, I built up a B1 with 2SK289 and the split rail psu based on LM317. 10uF MKP at the outputs, bypassed by sowjet caps.
An externally hosted image should be here but it was not working when we last tested it.
I will try this circuit soon.
Franz
1/4w and 1% is ok for resistors right?
the mkt 1,5 have 400v is this ok too? the 5,6 also has 400v..
here is a link:
http://www.reichelt.de/?ACTION=3;ARTICLE=12308;PROVID=2402
they look ugly
the mkt 1,5 have 400v is this ok too? the 5,6 also has 400v..
here is a link:
http://www.reichelt.de/?ACTION=3;ARTICLE=12308;PROVID=2402
they look ugly
You got me before I got to bed.
400v is fine, with resistors the larger values should give more weight to the sound, so half watt or 1 watt might be better, but quarter is OK.
Edit:Oh dear god! they are ugly!
Any combos of the Wima's that you can use?
My German is, well zero... so I have trouble getting around that site
I must say goodnight now.
400v is fine, with resistors the larger values should give more weight to the sound, so half watt or 1 watt might be better, but quarter is OK.
Edit:Oh dear god!
they are ugly!Any combos of the Wima's that you can use?
My German is, well zero... so I have trouble getting around that site
I must say goodnight now.
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