ZM -
Quick confirmation for stuffing, please.
1) On schematic, there are 11 places for 100R. 104, 108, 111, 112, 115, 116, 119, 120, 127, 130, and 131. 22 total with L channel. Is this correct for latest schematic. I reviewed full thread for the different options, but I am using standard schematic from post #1. Only 18 parts in baggie. No problem, I have extra, but do not want to mis-stuff.
2) Did you change C108 and C101 to 10uF? I did not see in previous posts. Again, no worry, but do not want to mis-stuff.
3) Got 4 pieces 270R. Only found R122 (R222) on schematic. I re-read a few times. What is the location for the the second pair?
With thanks!
Quick confirmation for stuffing, please.
1) On schematic, there are 11 places for 100R. 104, 108, 111, 112, 115, 116, 119, 120, 127, 130, and 131. 22 total with L channel. Is this correct for latest schematic. I reviewed full thread for the different options, but I am using standard schematic from post #1. Only 18 parts in baggie. No problem, I have extra, but do not want to mis-stuff.
2) Did you change C108 and C101 to 10uF? I did not see in previous posts. Again, no worry, but do not want to mis-stuff.
3) Got 4 pieces 270R. Only found R122 (R222) on schematic. I re-read a few times. What is the location for the the second pair?
With thanks!
1. of course that's my ookup in counting ( or I left that to Eagle and Eagle ook me up) ; put whatever close you have , not critical at all ; just take care to have that one in series with optoled as 100R , and gate resistors for outputs
2. 470uF is important , rest of them can be anything from 10u-47u , as long they're Pana or something
3. I did send , hopefully , all values needed to cover whatever arrangement of outputs you're going to use ........ so , finally , I wasn't beancounting
resistors
2. 470uF is important , rest of them can be anything from 10u-47u , as long they're Pana or something
3. I did send , hopefully , all values needed to cover whatever arrangement of outputs you're going to use ........ so , finally , I wasn't beancounting
resistors
Hi ZM -
Getting ready for the "serious" section of building and testing. I have reviewed all posts many times, but I lack some information. It could could be easy for others, but I cannot find it or determine it 100% myself.
For proper start-up / testing -
1) Set Iq - I searched thread. I know generally that 35W per device is "normal" maximum or 55C to sinks - 65 on device for this type of package. For "safe" condition at startup. Maybe 15W per device?
Confirming that P102 (202) to set bias. Should I measure across PSU resistors similar to SissySIT? Target what voltage / Iq?
15W per device (30W) through 0.1175 => 1V88 measured on PSU filter resistors?
I have a hard time understanding this key piece. Thank you!
2) DC offset - Normal. Short input and null with P101.
Any other things to be cautious with for checking and initial power up (after dim bulb check, of course)?
Getting ready for the "serious" section of building and testing. I have reviewed all posts many times, but I lack some information. It could could be easy for others, but I cannot find it or determine it 100% myself.
For proper start-up / testing -
1) Set Iq - I searched thread. I know generally that 35W per device is "normal" maximum or 55C to sinks - 65 on device for this type of package. For "safe" condition at startup. Maybe 15W per device?
Confirming that P102 (202) to set bias. Should I measure across PSU resistors similar to SissySIT? Target what voltage / Iq?
15W per device (30W) through 0.1175 => 1V88 measured on PSU filter resistors?
I have a hard time understanding this key piece. Thank you!
2) DC offset - Normal. Short input and null with P101.
Any other things to be cautious with for checking and initial power up (after dim bulb check, of course)?
Hi ZM -
Thank you!
I have been listening to Iron Pre with F5 since yesterday. Digital streaming from DAC source. Note, it is not in chassis or tidy yet. It is "open air". As you know, I have a challenging time with subjective impressions. Last night and all this morning while planning and building Babel J2 it has been on with variety of music. Mostly, I listen to 60's, 70's rock and Motown etc. Very little "fancy" or audiophile recordings. I did pick a few of my favorite tracks that I know very well though.
Best initial thought for me now is that it keeps (or adds to) all the detail of the F5 compared to when using the (insert some other retail) pre-amp. So maybe a better signal preservation??? I don't know how to describe. It's better detail (to me), but I feel the sound is easier for me to go a long time listening to than with the other pre-amp. It's sort of like how I feel about F5 vs. SissySIT or Aleph J. To me F5 (at the bias I am running now) is a crazy detail machine, and it seems to control the bass on my speakers a bit better than some amps. It may be my imagination. Either way, I wanted to keep the bass control with a bit easier sound. This seems to be a wonderful combination. I like to try different pairings like wine with food. It's hard to say best wine ... if I am eating certain food, I like certain wine...
I think I got pretty lucky I had the F5 in place for first trial with Iron Pre.
Thank you!
I have been listening to Iron Pre with F5 since yesterday. Digital streaming from DAC source. Note, it is not in chassis or tidy yet. It is "open air". As you know, I have a challenging time with subjective impressions. Last night and all this morning while planning and building Babel J2 it has been on with variety of music. Mostly, I listen to 60's, 70's rock and Motown etc. Very little "fancy" or audiophile recordings. I did pick a few of my favorite tracks that I know very well though.
Best initial thought for me now is that it keeps (or adds to) all the detail of the F5 compared to when using the (insert some other retail) pre-amp. So maybe a better signal preservation??? I don't know how to describe. It's better detail (to me), but I feel the sound is easier for me to go a long time listening to than with the other pre-amp. It's sort of like how I feel about F5 vs. SissySIT or Aleph J. To me F5 (at the bias I am running now) is a crazy detail machine, and it seems to control the bass on my speakers a bit better than some amps. It may be my imagination. Either way, I wanted to keep the bass control with a bit easier sound. This seems to be a wonderful combination. I like to try different pairings like wine with food. It's hard to say best wine ... if I am eating certain food, I like certain wine...
I think I got pretty lucky I had the F5 in place for first trial with Iron Pre.
left-right , and setting procedure
leftisleft and rightisright when pcbs are mounted on L brackets
when mounted directly , leftisright and rightisleft
regarding first run and setting procedure ..... if you did check everything and you're happy how smart and capable you are , and you were smart enough to pre-set trimpots somewhere in mid position ( and you confirmed that with ohmmeter) .......
- you were so smart to solder PSU wires just to one channel pcb , or in case you did dual mono - put mains fuse just for channel you're working on now;
- no load connected to output
- both inputs ( pos and neg) grounded
- connect (( with miniclips) one DVM across one of 3W 1R resistors ;
- connect second DVM to output of same channel
- bang bloody thing ON
- fiddling with both Px01 and Px02 , set that you have as close to 0mV you can get on output and (say) 850mV across said 1R/3W resistor ; that corresponds to 1A7 of Iq
let am get some heat , keep one eye on both DVMs
repeat some trimpot twiddling , if necessary , up to temp equilibrium
....................... repeat same procedure with second channel
put lid on , keep DVM at output , let amp cool off , power it again and let it again to temp. equilibrium , keeping an eye on DC offset
if it's good , power off , connect speaker and source , bang! and enjoy
leftisleft and rightisright when pcbs are mounted on L brackets
when mounted directly , leftisright and rightisleft
regarding first run and setting procedure ..... if you did check everything and you're happy how smart and capable you are , and you were smart enough to pre-set trimpots somewhere in mid position ( and you confirmed that with ohmmeter) .......
- you were so smart to solder PSU wires just to one channel pcb , or in case you did dual mono - put mains fuse just for channel you're working on now;
- no load connected to output
- both inputs ( pos and neg) grounded
- connect (( with miniclips) one DVM across one of 3W 1R resistors ;
- connect second DVM to output of same channel
- bang bloody thing ON
- fiddling with both Px01 and Px02 , set that you have as close to 0mV you can get on output and (say) 850mV across said 1R/3W resistor ; that corresponds to 1A7 of Iq
let am get some heat , keep one eye on both DVMs
repeat some trimpot twiddling , if necessary , up to temp equilibrium
....................... repeat same procedure with second channel
put lid on , keep DVM at output , let amp cool off , power it again and let it again to temp. equilibrium , keeping an eye on DC offset
if it's good , power off , connect speaker and source , bang! and enjoy
Thanks, ZM!
Board marked left channel biased up on test quite nicely. Have not baked to null offset, but it started at 0V000 until I played with the pot to see if I was getting a proper measurement, then it started drifting. Silly me. I will null once it has baked
The board marked as right channel had a problem with the dim bulb check. I have a problem somewhere on the amp board. The PSU checked fine (and has worked for a long time). I tried some continuity checks for key places. Nothing looks funny, but the bulb test acts like I have a short. (Bulb stays bright and does not dim).
With PSU disconnected and board mounted to sinks -
No continuity from output FET pins to Sink or GND (with PSU disconnected).
No continuity from V+ to Sink or GND
No continuity from V- to Sink or GND
No continuity from In+ or In- to Sink or GND
No continuity from GND to Sink
No continuity from Output to V+, V-, GND, or Chassis
I'll take a break and come back to it. Are there any other simple things to check that you can advise? Next step is to remove the board and inspect again.
Board marked left channel biased up on test quite nicely. Have not baked to null offset, but it started at 0V000 until I played with the pot to see if I was getting a proper measurement, then it started drifting. Silly me. I will null once it has baked
The board marked as right channel had a problem with the dim bulb check.
I have a problem somewhere on the amp board. The PSU checked fine (and has worked for a long time). I tried some continuity checks for key places. Nothing looks funny, but the bulb test acts like I have a short. (Bulb stays bright and does not dim). With PSU disconnected and board mounted to sinks -
No continuity from output FET pins to Sink or GND (with PSU disconnected).
No continuity from V+ to Sink or GND
No continuity from V- to Sink or GND
No continuity from In+ or In- to Sink or GND
No continuity from GND to Sink
No continuity from Output to V+, V-, GND, or Chassis
I'll take a break and come back to it. Are there any other simple things to check that you can advise? Next step is to remove the board and inspect again.
After a bit over an hour, things are stable.
Bias reduced slightly after warming. I can't get past 0V841 on one side and 0V843 the other with trimmers maxed, but that is close enough for now. ZM - should I swap R123 or leave it alone? Is that the right resistor to alter for increased bias ability and keeping some range in trimmer? If so, do you have a suggested value?
DC nulled. One more hour with top on, then music. Sinks hardly warm.
Bias reduced slightly after warming. I can't get past 0V841 on one side and 0V843 the other with trimmers maxed, but that is close enough for now. ZM - should I swap R123 or leave it alone? Is that the right resistor to alter for increased bias ability and keeping some range in trimmer? If so, do you have a suggested value?
DC nulled. One more hour with top on, then music. Sinks hardly warm.