You should measure the source that you expect to use with the FE and MoFo. You do not need to connect it to the FE and amplifier and speakers to measure the output voltage of the source.
Play some music, download some sine wave files and play them. Measure the AC voltage at the output. With music play some music that is continuously loud. See what the voltage maxes out at.
Play some music, download some sine wave files and play them. Measure the AC voltage at the output. With music play some music that is continuously loud. See what the voltage maxes out at.
I wish to run all sources through BA-3, FE 22 V0, FE V1, Zen Iron, Salas, B1, Korg, Whammy, Wayne, 2nd Gen Wayne, CD, Phono, and all that I've missed here.
Nothing has failed until Ba-3 and FE22 with MOFO.
I can switch in real time all speakers with Nad Pre.
I am extremely sorry I can not at this time do as suggested. Can only relate back to what I have found so far immediately upon turning FE on and discovering both channels now work. I have to finish the pre's to the stage where they finally produce music in both channels. And will not destruct due to being jury-rigged. They have been forced to undergo extreme trouble shooting due to house wiring, brown outs failed parts, and broken wiring. The pic enclosed shows that. To trouble shoot the pre must be taken completely apart. Dual Mono in a small case has it's own problems.
The BA-3 has undergone all the same trama. It still has not found its voice on the one channel. I need to make another board and Install it same as was done to FE22.
I don't have the skills to measure a failed pre that does not yet procduce music to find the problem for information you are asking. When the FE is together and not spread out over itself that can be done. I can do the same for the MOFO. I can do it for the source. I can do it for all the sources.
To do this all at once and before the pre is stable and or even working is impossible. For me. Can an amp that has a failed board produce the data you need? Maybe. If I measure only one channel. What's the point?
Yes, I can put the now working unfinished FE aside, where I don't know, to prevent it from being damaged to take the advice and return the information asked for. Then get it back in one piece to take measurements on that.
Since I am doing all this to get the pre's to at least produce let alone at volume I can only suggest my source has never failed in near 50 years which is the point we are at.
All advise has been appreciated and will be acted upon. Unfortunately not in a timely enough manner.
Had to wait until house was up.
Output V at source playing sine wave is ,6
Output V at source playing musick is .2-.9.
Putting both through NAD amp no problems with volume on 4 seperate speakers.
Source to NAD Pre out to MOFO is 3.75V Sine Gen
This is way under what Ben Mah suggests except for NAD PRE.
As I mentioned in post #1088, the source needs to output about 1.4Vrms to max out the Big MoFo if both the DIY FE and MoFo are working properly.
You should measure the output voltage of your source first to confirm that it can output enough voltage.
Output V at source playing sine wave is ,6
Output V at source playing musick is .2-.9.
Putting both through NAD amp no problems with volume on 4 seperate speakers.
Source to NAD Pre out to MOFO is 3.75V Sine Gen
This is way under what Ben Mah suggests except for NAD PRE.
As I mentioned in post #1088, the source needs to output about 1.4Vrms to max out the Big MoFo if both the DIY FE and MoFo are working properly.
You should measure the output voltage of your source first to confirm that it can output enough voltage.
The gain of the FE should be 10X if built according to the schematic. So something is not working properly if you measured 5.96V in and 5.9V and 11.69V out respectively.
As for the NAD amplifier, it has a built-in front end with voltage gain. The MoFo is a single stage source follower with no voltage gain and no built-in front end with voltage gain. The MoFo therefore needs a preamp with much higher voltage gain or alternatively a regular gain preamp and a voltage gain front end.
Your source seems to have output that is a bit lower than typical.
By the way, the maximum output voltage of the DIY FE is approximately 20V, so no need to input more than 2V for testing.
As for the NAD amplifier, it has a built-in front end with voltage gain. The MoFo is a single stage source follower with no voltage gain and no built-in front end with voltage gain. The MoFo therefore needs a preamp with much higher voltage gain or alternatively a regular gain preamp and a voltage gain front end.
Your source seems to have output that is a bit lower than typical.
By the way, the maximum output voltage of the DIY FE is approximately 20V, so no need to input more than 2V for testing.
Had a think in hospital. I did not remove the 100K extra R3/4 from one channel on Pass FE. It took all night to setup to measure the little I provided. Could be why reading 11.69V. I have to setup and measure again. Or something I still don't see.
Source is computer files and Sine Gen. I have no idea how that is yet speakers attached the volume is fine at your observed lower V.
Still need to run CD player and measure.
Can you please check R1 and R2 if they are 10K (and not 100k)?
The doubling of gain in one channel makes sense since you added extra 100K R3/R4. But your lower 'base' gain seems to be just x1 (unity gain). If somehow if you have R1 and R2 also at 100K that would explain your 5.94V in and 5.9V out measurement.
The doubling of gain in one channel makes sense since you added extra 100K R3/R4. But your lower 'base' gain seems to be just x1 (unity gain). If somehow if you have R1 and R2 also at 100K that would explain your 5.94V in and 5.9V out measurement.
Thanks again for all the help.
So far I can play musick trough Pass FE at maximum pot volume to MOFO.
To compare in real time playing through NAD I can't go to 10 let alone 11 before speakers are falling off stands.
Pass FE and MOFO at Maximum equals SPL Nad at 9 'o' clock.
Could it be the pot on Pass FE is wrong value? I have others I could try.
So far I can play musick trough Pass FE at maximum pot volume to MOFO.
To compare in real time playing through NAD I can't go to 10 let alone 11 before speakers are falling off stands.
Pass FE and MOFO at Maximum equals SPL Nad at 9 'o' clock.
Could it be the pot on Pass FE is wrong value? I have others I could try.
Potentiometer position means nothing. Potentiometer value does not affect gain.
Your FE has a gain of 10. Your MoFo has a gain of just a teeny bit less than 1, but consider it unity gain.
So your total system gain is 10. Gain is not power.
Question - with FE+MoFo all the way up, is it too loud to listen to? Would real listening levels be at less than full twist, or do you need more gain/volume?
Your FE has a gain of 10. Your MoFo has a gain of just a teeny bit less than 1, but consider it unity gain.
So your total system gain is 10. Gain is not power.
Question - with FE+MoFo all the way up, is it too loud to listen to? Would real listening levels be at less than full twist, or do you need more gain/volume?
No. Comparable to a quiet public movie house. Old school movie with no explosions. No need to raise voice. To me it's comfortable listening in a quiet room. Not in a maschine shop envirenment or in my time of troubles dealing with neighbors that refuse county statutes and visits by police.
Need way more twist. I'm at maximum to slightly less. Depending on the Musick.
I just put on Bach's Orgel Werks. Way too quiet at maximum. Can't hear the orgel breath.
If I did this on NAD Volume would be slightly past 9. Maximum on NAD is fantastic. That would be between 3 and 5 o clock.
Let me add this observation running one of the current buffer amps...
Running an F4 and driving it with a tube preamp that has a 20V max output and a DAC that outputs 2V. ( Preamp has the gain to take 2V input to 20V output, gain of 10 ).
With 90 db/w speakers, volume at 2 o'clock....max. Sounds loud enough to play rock. About 10.5.
With 85 db/w speakers, volume at 4 o'clock... max. Sounds great, but only 8 out ot 10. No rock, otherwise it runs out of power.
With 83 db/w speakers, volume at 5 o'clock I hear the amp running out of power.. Very nice sound, but...maybe only 7 out of 10.
This is a full 35 watts ( speakers are either 6 or 4 ohms ).
Mind you, when I hook up the A5 (or any other 'normal' high powered amp) to the 83 db/w speakers, they rock. Usually the preamp will go to 10 o'clock max... 11 o'clock will peel the paint off the walls. - Well, being Maggies... they really don't go to 11, but you get the point here.
So again, either your source is too quiet or you need more efficient speakers. Or you need an F4 insteal of the MoFo.
Don't compare the NAD with the MoFo...
Running an F4 and driving it with a tube preamp that has a 20V max output and a DAC that outputs 2V. ( Preamp has the gain to take 2V input to 20V output, gain of 10 ).
With 90 db/w speakers, volume at 2 o'clock....max. Sounds loud enough to play rock. About 10.5.
With 85 db/w speakers, volume at 4 o'clock... max. Sounds great, but only 8 out ot 10. No rock, otherwise it runs out of power.
With 83 db/w speakers, volume at 5 o'clock I hear the amp running out of power.. Very nice sound, but...maybe only 7 out of 10.
This is a full 35 watts ( speakers are either 6 or 4 ohms ).
Mind you, when I hook up the A5 (or any other 'normal' high powered amp) to the 83 db/w speakers, they rock. Usually the preamp will go to 10 o'clock max... 11 o'clock will peel the paint off the walls. - Well, being Maggies... they really don't go to 11, but you get the point here.
So again, either your source is too quiet or you need more efficient speakers. Or you need an F4 insteal of the MoFo.
Don't compare the NAD with the MoFo...
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From same source I can run a 100W Sony or the 40W NAD using the junk speakers on the MOFO now to earbleed.
MOFO and Pass FE, I can physically hook up the other better speakers. I have not due to my issues here with power and other problems electically. I wanted time on the MOFOs to proof them.
To rule everything out that is certainly something I can do with some time.
Thanks H.
I can't do this now. Can't change speakers as they sit. It will take days to drag my best proven speakers into the place the junkers occupy. Hook them up to MOFO and PASS FE.
That's a fairly low source output value, but it doesn't surprise me coming from a computer. BUT, it's good to see that the Pass FE is now at 10X. I hope it's now the same for both channels!
Two different pairs of speakers could have two very different sensitivity levels. Could you describe these two different pairs?
No. In this instance an F4 will have the exact same volume as MoFo.
The speakers are getting 5.9V, since all the voltage gain is in the FE. As units were not noted, let's do the math both ways...
5.9V from zero to the peak of the sine is 11.8Vpk-pk or 4.17Vrms
5.9V pk-pk is 2.08V
Power is Vrms^2/load
Assuming 8ohm speakers...
4.14^2 = 17.4
17.4 /8= 2.17W
``
2.08^2 =4.32
4.32 /8 = 0.54W
You need a front-end with more gain.