The F4 is up and running since a couple months, it took a while to get it assembled but it was faulty, bad soldering, can tell that something went wrong and in the rush to send to me didn't even bias it... whatever, it got fixed, anzi, upgraded and now is in fully working conditions.
At this moment in time I am running it with my ancient Audio Research SP9 whose 20db gain don't really make it, I had a BA3 assembled but it needs some fine tune which is not gonna happen any time soon, on paper the gain should be plenty to drive the F4 but I am already looking forward at how to entertain myself next winter, actually before going dual mono route by building another F4 and bridging the one I already own (won't know how to do that but not this the thread about it) I wish to either mod the BA3 with twin output or to build another high gain preamplifier with just volume control and single or max dual sources, how about the Aleph 1.7, what's the output gain and what about it being coupled with the F4, anybody got the duo?
Grazie
At this moment in time I am running it with my ancient Audio Research SP9 whose 20db gain don't really make it, I had a BA3 assembled but it needs some fine tune which is not gonna happen any time soon, on paper the gain should be plenty to drive the F4 but I am already looking forward at how to entertain myself next winter, actually before going dual mono route by building another F4 and bridging the one I already own (won't know how to do that but not this the thread about it) I wish to either mod the BA3 with twin output or to build another high gain preamplifier with just volume control and single or max dual sources, how about the Aleph 1.7, what's the output gain and what about it being coupled with the F4, anybody got the duo?
Grazie
if having today normal source with 2Vrms out, SP9 is outputting 20Vrms, which is more than enough to drive F4 to full power
we are asking all the time that you measure gain of your SP9, to confirm its gain
that's only way for you ( and us) to determine what's your exact problem with said combo - lack of gain or maybe you want different sound or lack of power for your speakers from F4 (that one unlikely, taking in account that your speakers are pretty efficient)
now, either measure that or I fear it is not going to be last thread you're opening, chasing same things
all you need for gain measurement is DMM set to Vac and any sort of source set to 1KHz sine
that can be even your phone with app for sine, or your laptop with prog for sine
then you measure input sine level (with DMM) and output of SP9 (with DMM); don't forget to turn volume all up
anyhow, I believe that's already written about - check page 3/7, jumper "A", it must be in place; https://www.arcdb.ws/Database/SP9/ARC_SP9_manual_schematic_and_parts_list.pdf
we are asking all the time that you measure gain of your SP9, to confirm its gain
that's only way for you ( and us) to determine what's your exact problem with said combo - lack of gain or maybe you want different sound or lack of power for your speakers from F4 (that one unlikely, taking in account that your speakers are pretty efficient)
now, either measure that or I fear it is not going to be last thread you're opening, chasing same things
all you need for gain measurement is DMM set to Vac and any sort of source set to 1KHz sine
that can be even your phone with app for sine, or your laptop with prog for sine
then you measure input sine level (with DMM) and output of SP9 (with DMM); don't forget to turn volume all up
anyhow, I believe that's already written about - check page 3/7, jumper "A", it must be in place; https://www.arcdb.ws/Database/SP9/ARC_SP9_manual_schematic_and_parts_list.pdf
Ciao @Zen Mod, the BA3 is here, unfortunately, as I wrote in the thread, there is a hum which is very deep and low with the tube amp and high and thin on the F4, probably a BT module that the builder added to give the ability to stream music off of a mobile device, I made a test, upon his suggestion, by removing power to the BT module and the hum disappeared but we are both very busy at the time to fix the issue so I am still listening with the SP9 whose ex owner had interrupted the board track to lower the output gain and which my friend reset back by adding a jumper so that just in case it can be modified without to use a soldering iron.
Gain wise I got a 1Khz sine wave lasting 1 minute onto my laptop, I made the measurement but now can't recall the values, I will do it again with both the SP9 and the BA3 to figure the difference (output the 1Khz tone to one of the preamp inputs, turn volume all the way up and check AC output on the preamp).
I anyway want to put the BA3 in a smaller case, I used a same sized one as the F4 to match but I find it big and ugly, I planned it being dual mono but my guy only wired one of the two PSU and, so far, it seems the second is pointless so might remove both the second PSU and transformer and move it all in a smaller case as space here is precious.
You all know I am no tech at all and I would have liked to have a dual output for an eventual biamp but my guy told me, if I recall correct, impedance would half and dunno what that would cause to the pre-amp combo.
Still I'd like to look forward and think of another pre to match the F4 if it only was to learn a bit more about how it works and the whole process of dimensioning, assembling and tuning, I am not the kind of person who is satisfied by plugging and having it to work ;-)
About time to go work, have a nice day
G
Gain wise I got a 1Khz sine wave lasting 1 minute onto my laptop, I made the measurement but now can't recall the values, I will do it again with both the SP9 and the BA3 to figure the difference (output the 1Khz tone to one of the preamp inputs, turn volume all the way up and check AC output on the preamp).
I anyway want to put the BA3 in a smaller case, I used a same sized one as the F4 to match but I find it big and ugly, I planned it being dual mono but my guy only wired one of the two PSU and, so far, it seems the second is pointless so might remove both the second PSU and transformer and move it all in a smaller case as space here is precious.
You all know I am no tech at all and I would have liked to have a dual output for an eventual biamp but my guy told me, if I recall correct, impedance would half and dunno what that would cause to the pre-amp combo.
Still I'd like to look forward and think of another pre to match the F4 if it only was to learn a bit more about how it works and the whole process of dimensioning, assembling and tuning, I am not the kind of person who is satisfied by plugging and having it to work ;-)
About time to go work, have a nice day
G
You seem to want to be a bit more involved. Are you going to do the work yourself this time? You were originally going to build your F4 and your BA-3. IMO, the person/people that built them for you did not do either of them properly. They continued to send you things that should have never left the shop. They clearly never measured the products for basic audio performance before sending them back to you. More importantly, they sent you one iteration of your F4 that was frankly dangerous. They did not build your BA-3 as a dual mono project which was one of your requests, and they seem to make excuses (bad ones) for returning sloppy work to you. Everyone makes mistakes, but I certainly would never use them again. If that is all you expected from them, then I dare say that you could have done a much better job yourself with a little help from this community.
If you are going to build the next one... and do any repairs and upgrades to the BA-3 yourself, then I'll hop back in and walk you through what's needed as we started to do via e-mail for the build. If you continue to send your gear to this other person for build and repair, then that is their job... and you will likely have similar outcomes to the first two projects. I will not continue to participate. It will be a waste of time.
Two other things...
1) You do not need a dual mono F4 in order to run it bridged. The factory F4 was not dual mono. I'm not sure why you keep saying that. It might just be a mix in terms. Just run the one you have bridged on one channel, and see if it does what you want / expect. Then decide if you need/want to have another one. Please explain why you want to run it bridged. You do not have any pre-amps (that you've mentioned that I can see) with balanced outputs. Are you wanting to run it bridged from an SE pre-amp? Do you know how? If not... then you'll need to add that to your list of criteria for your next pre-amp. Pause on thinking you need another F4. Right now... you just want it louder... I understand.
2) For the pre-amp - To learn more... I'd strongly recommend that YOU fix your current BA-3 and determine why the SP9 is not living up to expectations. Don't get another pre-amp (yet).
You asked the gain for the Aleph 1.7. LOOK IT UP. You likely could have found the answer faster than the time it took to ask the question.
Lastly... please stop creating a new thread for every issue / question. It makes it harder for people trying to help. We need to look up what's happened in the past. If it's even slightly related to F4 or BA-3 and finding something that works with your F4 ... use this thread or one of your many other threads to continue discussion.
All of this is just my opinion /
Seriously. I hope you get it all sorted for beautiful music. You've certainly been though some challenges.
If you are going to build the next one... and do any repairs and upgrades to the BA-3 yourself, then I'll hop back in and walk you through what's needed as we started to do via e-mail for the build. If you continue to send your gear to this other person for build and repair, then that is their job... and you will likely have similar outcomes to the first two projects. I will not continue to participate. It will be a waste of time.
Two other things...
1) You do not need a dual mono F4 in order to run it bridged. The factory F4 was not dual mono. I'm not sure why you keep saying that. It might just be a mix in terms. Just run the one you have bridged on one channel, and see if it does what you want / expect. Then decide if you need/want to have another one. Please explain why you want to run it bridged. You do not have any pre-amps (that you've mentioned that I can see) with balanced outputs. Are you wanting to run it bridged from an SE pre-amp? Do you know how? If not... then you'll need to add that to your list of criteria for your next pre-amp. Pause on thinking you need another F4. Right now... you just want it louder... I understand.
2) For the pre-amp - To learn more... I'd strongly recommend that YOU fix your current BA-3 and determine why the SP9 is not living up to expectations. Don't get another pre-amp (yet).
- Start with measuring the gain again for both pre-amps. This was asked SO many times. Don't look it up. Do it again. It should take less than 10 mins. Tell us exactly how (with pictures) you did it. Stop quoting the 20dB gain for the SP9 when you know it's been modified, and you don't know if that's accurate.
- Make sure to tell us which input(s) and output(s) you're using on the SP9. There are various gain structures with that pre-amp. Again, if it's been modified... who knows.
- Gain is (should be) independent of the volume setting for both pre-amps. ZM may want to see Vrms of output at full volume with your phone or laptop as input. I'd suggest doing it at a couple volume levels (including full) to see if there is anything else fishy. I would do middle and max on laptop/phone and middle and max on pre-amps at least.
You asked the gain for the Aleph 1.7. LOOK IT UP. You likely could have found the answer faster than the time it took to ask the question.
Lastly... please stop creating a new thread for every issue / question. It makes it harder for people trying to help. We need to look up what's happened in the past. If it's even slightly related to F4 or BA-3 and finding something that works with your F4 ... use this thread or one of your many other threads to continue discussion.
All of this is just my opinion /
Seriously. I hope you get it all sorted for beautiful music. You've certainly been though some challenges.
how's that?
yes, if you're measuring bare pcb ( without having volume pot)
but in context of finished preamp, volume pot is always in chain and you must crank it to max, to get it out of picture
^ Totally my fault. Thank you for calling that out. 
Measuring gain the way he will do it will be 100% dependent on the pot being in the circuit. Circuit gain / total available gain is same / fixed.
Vin will be the same (unless he varies) Vout will depend on volume setting on pre-amp => measured gain will vary.
I'll go have coffee, but that may not be enough for that ookup.
Measuring gain the way he will do it will be 100% dependent on the pot being in the circuit. Circuit gain / total available gain is same / fixed.
Vin will be the same (unless he varies) Vout will depend on volume setting on pre-amp => measured gain will vary.
I'll go have coffee, but that may not be enough for that ookup.
Using a DAC with 2Vrms output, I get enjoyable listening levels out of an F4 on some 90dB sensitive speakers. It is surprising that an AR preamp is not meeting the need to feed. Something seems amiss.
As others have asked, what is the measured gain? Also, what is the sensitivity of the speakers you are using? Might also want to measure the "gain" of the F4 to see if it is functioning correctly.
Better to take some measurements and shed some light instead of groping in the dark. Unless that is the intended journey. Can be rewarding in its own weird way.
As others have asked, what is the measured gain? Also, what is the sensitivity of the speakers you are using? Might also want to measure the "gain" of the F4 to see if it is functioning correctly.
Better to take some measurements and shed some light instead of groping in the dark. Unless that is the intended journey. Can be rewarding in its own weird way.
Did the measurements, 1Khz sine wave off of my MacBookAir, full volume out, input into preamp line in, measured on the main output and surprise surprise I have 4.09VAC for the SP9 and 4.2VAC out of the BA3, at this point I think something is wrong with the latter as it should have way more gain but now it's up to you to tell me what should have I got out of them both and, by the way, let's close this thread, I rather check in the BA3 as a preamp build one.
Grazie
edit, about 120mV out of the DAC, playing the same 1Khz sine wave off the MacMini which streams music to the DAC then to the preamp, the most reliable thing coming to my mind now is the CD player but where do I get a 1Khz signal?
Grazie
edit, about 120mV out of the DAC, playing the same 1Khz sine wave off the MacMini which streams music to the DAC then to the preamp, the most reliable thing coming to my mind now is the CD player but where do I get a 1Khz signal?
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I am using edcor step up between computer and f4/ adason buffer. Without the edcor, i need to put headphone output to max on computer. With trafo, wired for 3x and 6x amplification, i need to turn computer down, about 20% volume. This is just test setup for fun.
Has been experimenting with tvc.
Has been experimenting with tvc.
Attachments
Hi 4v ac is ~+14dbu which would make your macbook output in the range of -6dbu (0,38v ac) as your SP9 have 20 db gain. Something is weird, the macbook should be higher in level.
What do you use as cable? And how it is wired? Minijack? If so maybe you are shorting through cable.
Have you your software levels at max out?
Edit: there is definitely something weird with your computer output ( 1,23v is +4dbu and 3v is circa 12dbu):
https://support.apple.com/en-us/HT212856
Maybe you should try with 50hz rather than 1khz test tone: standard/cheap multimeters are ok to measure grid frequency but can have issues with higher freq.
What do you use as cable? And how it is wired? Minijack? If so maybe you are shorting through cable.
Have you your software levels at max out?
Edit: there is definitely something weird with your computer output ( 1,23v is +4dbu and 3v is circa 12dbu):
https://support.apple.com/en-us/HT212856
Maybe you should try with 50hz rather than 1khz test tone: standard/cheap multimeters are ok to measure grid frequency but can have issues with higher freq.
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that's the price of asking the same and writing about the same in 50 different threads
and finally trying in 51-st what's asked in first thread of them all
I'm out, I'm simply not fast enough to follow what's happening
(for non-initiated, it seems that with CD player, now there's finally some loud music; I've read hat in some other random thread)
and finally trying in 51-st what's asked in first thread of them all
I'm out, I'm simply not fast enough to follow what's happening
(for non-initiated, it seems that with CD player, now there's finally some loud music; I've read hat in some other random thread)
Giovanni,
I second krivium's suggestion of trying a low frequency signal since some meters have issues with higher frequencies.
May I also make the suggestion that you contact a moderator to merge this thread into your most recent one? This is making it very difficult for the members trying to help you to keep track of what has been done, what has been asked, etc.
I second krivium's suggestion of trying a low frequency signal since some meters have issues with higher frequencies.
May I also make the suggestion that you contact a moderator to merge this thread into your most recent one? This is making it very difficult for the members trying to help you to keep track of what has been done, what has been asked, etc.
Sometimes when building a project , its easy to start questioning if you are going in the right direction .
However , I would suggest completing the BA-3 you've started .
I joke that the power supply is 1/2 the sound . So for the BA-3 , suggest the following
Fo Felix DIY EMI filter ==> split bobbin transformer ==> AMB Labs sigma 22 power supply board ==> BA -3
For the transformer , Hammond makes the 229 series . These only go up to a power rating of 48VA ,
but that should be plenty to power a BA- 3 .But these transformers need mounting on a circuit board .
IMO the great advantage of a split bobbin transformer is that there is low capacitive coupling between the
primaries and secondaries .
http://www.hammondmfg.com/pdf/229Insert.pdf
https://www.amb.org/audio/sigma22/
WARNING : Subjective Comment . I've done a subjective listing test to a number of high quality coupling caps .
Including Mundorf Supremes , original Auri Caps and expensive all copper caps - which are massive beasts .
For the coupling cap on the BA-3 , IMO the Clarity Cap CSA series is very good .
By passing it with 10nF sprague orange drop 716p series , or an 8.6nF Russian silver mica will improve it even more .
If the real estate can be found on the BA-3 board for the by pass cap .
.
On paper the BA3 should be the perfect match for the F4, I had it assembled with, if I recall correct, about 30V to allow it for both max gain and min distortion, dual mono as well as the F4; the guy who put it together for me added a bonus in the form of a BT receiver so that I could stream music off a mobile device for casual listening, unfortunately it causes a deep and loud hum on the tube amp I own and a higher pitch but thinner hum with the F4, the gain is slightly higher than the Audio Research SP9 but can't yet tell if once in working order it would make it loud enough so that I won't regret the tube amp (which is still there by the way!).
Here you can see the two Sigma22 PSU but only one is connected, dunno why the decision not to wire both, so far he said one is enough to drive the whole thing and I knew that already but the dual mono design at this point doesn't make sense so either connect the second PSU or remove the excess, get a smaller case and remake it as to take less footprint as space here is precious.
I wanted also to have dual output but so far seems the impedance would halve, dunno what would that cause but I left the world as it is and waiting for the hum to be fixed, he said he found an Harman KArdon BT module (it's below the iSelect board the actual BT module) which might work, if you guys think there is else to make this thing better please go ahead.
Grazie
Here you can see the two Sigma22 PSU but only one is connected, dunno why the decision not to wire both, so far he said one is enough to drive the whole thing and I knew that already but the dual mono design at this point doesn't make sense so either connect the second PSU or remove the excess, get a smaller case and remake it as to take less footprint as space here is precious.
I wanted also to have dual output but so far seems the impedance would halve, dunno what would that cause but I left the world as it is and waiting for the hum to be fixed, he said he found an Harman KArdon BT module (it's below the iSelect board the actual BT module) which might work, if you guys think there is else to make this thing better please go ahead.
Grazie
Dear @Zen Mod I don' know your name, where I live it seems like people don't take stuff too seriously, I take responsibility for my actions and as a service give in my work, not everybody is the same unfortunately, we have to accept pros and cons, when I had built the in-famous F4 it came home after a year (!!!) and it was not just not working but also damaged, about 50 pounds to carry in the metro in Napoli, then all the way to the docks, on a ferry then a funicular then home and when you go through something like that, believe you me, your best friend becomes the JBL boom box!!!
I found this guy here where I live, for the chronicles the island's name is Capri, he is super skilled for this stuff but he is behind other stuff where he earns the real money, I consider myself lucky as he fixed both the AR SP9 preamp and then had the patience to undo the F4, solder what was left unsoldered, fix what needed to be fixed and bias the whole thing which, after 15 min uphill then downhill to go to his place and back, is finally working and I am grateful to him as between 15 min and 17 miles to reach the mainland I prefer the former.
He got nice and patient enough to assemble the two PSU, the BA3 board, the two transformers, the iSelect, drill holes etc etc again, he did that onto his spare time, I can live with no music not to say have some spare electronics, I came to here first to understand what would fit my needs, hence the F4, then I came to understand what made so it didn't preform as expected and learnt a lot, on another thread I started asking about the PSUs to feed the BA3 as this seemed the perfect companion for the F4 and the few who attended the thread were very patient and very informative and, again, learnt a lot about that, then the BA3 as a preamp thread, lot of reading and questions and it came to life, not everything comes perfect and most of what comes unperfected can be improved.
After all of what I been through with the faulty electronics and all I read on this forum I wish some day to be able to put something together on my very own otherwise it would just be a futile exercise and a waste of time on both ends, mine and yours all...
Grazie for your attention, if as a moderator you have the power to delete threads please go ahead and start by deleting this
I found this guy here where I live, for the chronicles the island's name is Capri, he is super skilled for this stuff but he is behind other stuff where he earns the real money, I consider myself lucky as he fixed both the AR SP9 preamp and then had the patience to undo the F4, solder what was left unsoldered, fix what needed to be fixed and bias the whole thing which, after 15 min uphill then downhill to go to his place and back, is finally working and I am grateful to him as between 15 min and 17 miles to reach the mainland I prefer the former.
He got nice and patient enough to assemble the two PSU, the BA3 board, the two transformers, the iSelect, drill holes etc etc again, he did that onto his spare time, I can live with no music not to say have some spare electronics, I came to here first to understand what would fit my needs, hence the F4, then I came to understand what made so it didn't preform as expected and learnt a lot, on another thread I started asking about the PSUs to feed the BA3 as this seemed the perfect companion for the F4 and the few who attended the thread were very patient and very informative and, again, learnt a lot about that, then the BA3 as a preamp thread, lot of reading and questions and it came to life, not everything comes perfect and most of what comes unperfected can be improved.
After all of what I been through with the faulty electronics and all I read on this forum I wish some day to be able to put something together on my very own otherwise it would just be a futile exercise and a waste of time on both ends, mine and yours all...
Grazie for your attention, if as a moderator you have the power to delete threads please go ahead and start by deleting this