Obvious not to me as I know peeps in lots of foreign countries that speak better english than me.
Again, replacing both means something is amiss with the implemented circuit and shouldn't be considered. To second william2001, I temporarily jumpered a 10k resistor in parallel with R9 via alligator clip leads to test the 5k fix. Might be an option worth considering before tearing everything apart.
He sure knows that, the guy has been working to this stuff since and abundant 40 years and I have seen him arranging a 10Ghz transmitter which is no joke, since the project has been updated with the R8 22.1K to 27.4K as to allow more swing that's the first thing I put on the list of the check-fix.
I am impatient too but in the meantime I am listening to tubes which is not that bad ;-) and right yesterday he told me that the two PSU boards for the BA-3 preamplifier are up and running so the job is proceeding on both ends.
Dear @6sX7 I one of the few who doesn't speak a better English than yours, if this is such a barrier or such a pain for you I'd suggest to to what I do when I don't understand, either ask to repeat or just move on...
Hopefully you will have it back working properly soon.
I found it disappointing that the person who built it originally gave it to you incorrectly biased.
I found it disappointing that the person who built it originally gave it to you incorrectly biased.
It isn't a barrier or a pain. As others have tried to relay, just attempting to ensure you don't fry that beautiful amp. Good luck.
I sent an email to the guy who built it and who advertises himself as a tech on other forums, I told him that the sole fact he didn't even try to bias the amp says a lot about his knowledge and I kindly asked him to not even reply, I am still thorn at if to report what he did or, rather, didn't do for the sake of his eventual future customers or to just drop it and move on...
Re barrier or pain, I underlined more than once the fact I asked to replace R8 and then, EVENTUALLY, R9 and not both, at least not to begin with, it has been stressed so much that even if I was a Mandarin Chinese Mather language I would have got it 🙂 mind you, to you this sure sounds all normal as, as far as I can tell, you are American and this is your language, but this is a techie forum with some grammar which is totally new to me and even tho it wasn't anything new this still isn't my language and as far as I can try I sure make tons of mistakes which I also happen to go through with my language (which is waaaaaaay more complicated) so I am sorry about it and I am still grateful to the community for the support on both the tech side and the comprehension with the "barriers"😉
Joe (funnily we have same name and surname but his nick is Joe) texted me yesterday to report that the two Sigma22 PSUs are assembled and working fine, now it's about to put together the BA-3 and the iSelect boards, I still miss the volume pot, the knobs, case feet... I will be missing for a few days and hope than on my way back the F4 is back and working and that the BA-3 keeps moving towards completion, even tho I am not doing anything physically with the things it's so very interesting to try and understand what happens with this stuff, I learnt quite a few things thanks to you all guys and I hope my English too is improving...
Re barrier or pain, I underlined more than once the fact I asked to replace R8 and then, EVENTUALLY, R9 and not both, at least not to begin with, it has been stressed so much that even if I was a Mandarin Chinese Mather language I would have got it 🙂 mind you, to you this sure sounds all normal as, as far as I can tell, you are American and this is your language, but this is a techie forum with some grammar which is totally new to me and even tho it wasn't anything new this still isn't my language and as far as I can try I sure make tons of mistakes which I also happen to go through with my language (which is waaaaaaay more complicated) so I am sorry about it and I am still grateful to the community for the support on both the tech side and the comprehension with the "barriers"😉
Joe (funnily we have same name and surname but his nick is Joe) texted me yesterday to report that the two Sigma22 PSUs are assembled and working fine, now it's about to put together the BA-3 and the iSelect boards, I still miss the volume pot, the knobs, case feet... I will be missing for a few days and hope than on my way back the F4 is back and working and that the BA-3 keeps moving towards completion, even tho I am not doing anything physically with the things it's so very interesting to try and understand what happens with this stuff, I learnt quite a few things thanks to you all guys and I hope my English too is improving...
Giovanni,
I can't speak for others, but I was reacting to your post #115:
There was nothing about stopping if R8=27.4K works, and a literal reading of that post worried me and hence my post #116 raising my concern. (It might also be instructional for you to look at a TL431 datasheet to see how R8/R9/P1 work together.)
And to repeat 6sX7's sentiment from an earlier post, I also don't want you to have a mishap with these resistor changes and end up damaging the amplifier.
I can't speak for others, but I was reacting to your post #115:
There was nothing about stopping if R8=27.4K works, and a literal reading of that post worried me and hence my post #116 raising my concern. (It might also be instructional for you to look at a TL431 datasheet to see how R8/R9/P1 work together.)
And to repeat 6sX7's sentiment from an earlier post, I also don't want you to have a mishap with these resistor changes and end up damaging the amplifier.
any updates?
Also, with the dual mono supplies, what are the rail voltages? Always wondered how close they'd be for running balanced mono mode.
Also, with the dual mono supplies, what are the rail voltages? Always wondered how close they'd be for running balanced mono mode.
Ciao @6sX7 nope, no updates yet, fact being that my friend is working at the preamp at the moment, he is done with the PSUs which are working fine and I guess he wants to finish that before heading to the F4 and then test the two together which would be a good thing as to avoid other back and forth just in case something is not working properly.
Grazie for your concern, I will sure update you all once I hear from him working onto Mr F4
Grazie for your concern, I will sure update you all once I hear from him working onto Mr F4
Update update, went to pick it up after the restoration, pins of some drivers were not soldered on the left channel as well as one on the right one, removed the soft start and arranged a different one.
It is warming up now, I can tell straight away that finally it sounds but also true that the power is what it is, I have to go full throttle with the volume pot to obtain a good sound pressure, first impression is that the midrange is way more pronounced than with the tube amp, had to limit it with the speakers pots, the bass is there, "drier" and not boomy, feels a little weak...
I don't expect anything to change after the warm up but at least it sounds, now it all lies into the preamp which is almost finished, still needs to be fully wired but almost done, hopefully the extra 7-9db gain over the AR SP9 will make the difference.
Happy Easter everybody
It is warming up now, I can tell straight away that finally it sounds but also true that the power is what it is, I have to go full throttle with the volume pot to obtain a good sound pressure, first impression is that the midrange is way more pronounced than with the tube amp, had to limit it with the speakers pots, the bass is there, "drier" and not boomy, feels a little weak...
I don't expect anything to change after the warm up but at least it sounds, now it all lies into the preamp which is almost finished, still needs to be fully wired but almost done, hopefully the extra 7-9db gain over the AR SP9 will make the difference.
Happy Easter everybody
Happy Easter Giovanni, I have read numerous times that in the case of the F4 that the overall sound of the amplifier is largely determined by the sound or sound signature of the preamp feeding the F4. The preamp will also need a lot of voltage output to make the F4 output it’s full wattage.
Ciao @JSA1971 yep I know the F4 being a buffer is almost totally dependant on the source output, my SP9 outputs circa 21db while the BA-3 should be in the 28-30db range, can't remember now as I read ad nauseam and with limited knowledge I did sure learn a lot but easily forgot it all once I had to put the project on the side.
The BA-3 is almost ready, unfortunately one of the MOSFETs resulted faulty so waiting for the new one to come in, complete the wiring of the second PSU, checking voltages, adjusting the harmonic and crossing fingers.
The actual configuration sounds but lacks the push on the low end
The BA-3 is almost ready, unfortunately one of the MOSFETs resulted faulty so waiting for the new one to come in, complete the wiring of the second PSU, checking voltages, adjusting the harmonic and crossing fingers.
The actual configuration sounds but lacks the push on the low end
It is up since maybe one hour, listening to Alan Parson's Project's Eye in the sky, I can tell that bass is not even close to the tubes, true output power being 50% compared to the KT88, it sure sounds but doesn't have the push (and distortions 🙃 ) too early to pass even an opinion but should I use just one world I'd say "dry"
I'm crossing my fingers the BA3 will deliver.
Currently, I'm adding some tubes (a pair of Glass-ware SRPP boards) to my setup for two reasons:
1.) a little more gain
2.) I want to hear how different front ends sound.
I look forward to reading how the BA3 sounds compared to the SP9.
Currently, I'm adding some tubes (a pair of Glass-ware SRPP boards) to my setup for two reasons:
1.) a little more gain
2.) I want to hear how different front ends sound.
I look forward to reading how the BA3 sounds compared to the SP9.
Attachments
Sounds like the F4's damping factor of 40 is not the best match with your speakers. No idea what the output impedance / DF of a KT88 is but you obviously prefer the looser, floppier, loose leash, lack of control, etc of a toob amp.... that gives it that "fatter" bass. Maybe some series resistance could be added, I have no experience trying that myself, maybe someone else has.
I don't have the knowledge to know what a damping factor has to do with speakers, amp... all I know is that in the couple hours of casual listening I can tell that the bass is sure way more controlled but also skinnier, I should make a comparison between the two, something I expect to do along the end of this coming week, in the meantime I hope the mosfets will make it to my friend who is putting together the BA-3 so that I can test the couple together but, so far, I guess matter of getting used to the "new" solid state sound.
Grazie @6sX7 I am sure things will get better, 6-8 extra db means a lot more gain so it should sure deliver, if I'll like it is a different story but that's how it is...
Grazie @6sX7 I am sure things will get better, 6-8 extra db means a lot more gain so it should sure deliver, if I'll like it is a different story but that's how it is...
An extra 0r22 or 0r47 of resistance in series with your positive tap might be worth trying (has to be a power resistor). I've read that source impedance can have a large influence on speaker Q / bass perception.
Hmm... did you switch threads on this?
I've been running a Conrad Johnson PV9 with a single F4 into a pair of Audio Note AN-K LX speakers ( 90db/w). But I also use a pair of Entec SW5s.
No issues whatsoever with the gain... indeed, I can hear the F4 running out of power because the PV9 has sufficient gain: 20vrms->56Vpp... which is more than the 40Vpp that the F4 supports.
That's a tube preamp.. and I have no issues with the bass at all. The Audio Notes are being run full range, but they don't have the deep reach of the JBLs... However, the Entec woofers are very good and they have solid bass coming out of the preamp.
So, I don't know... is your BA3 working correctly? Remember the F4 sounds like the preamp.
Heck, for giggles I even plugged the F4 into the Maggie 1.7 speakers and it floored me. Sure, it lacked dynamics but it had some pretty convincing bass.
Maybe you do need a different speaker?
I've been running a Conrad Johnson PV9 with a single F4 into a pair of Audio Note AN-K LX speakers ( 90db/w). But I also use a pair of Entec SW5s.
No issues whatsoever with the gain... indeed, I can hear the F4 running out of power because the PV9 has sufficient gain: 20vrms->56Vpp... which is more than the 40Vpp that the F4 supports.
That's a tube preamp.. and I have no issues with the bass at all. The Audio Notes are being run full range, but they don't have the deep reach of the JBLs... However, the Entec woofers are very good and they have solid bass coming out of the preamp.
So, I don't know... is your BA3 working correctly? Remember the F4 sounds like the preamp.
Heck, for giggles I even plugged the F4 into the Maggie 1.7 speakers and it floored me. Sure, it lacked dynamics but it had some pretty convincing bass.
Maybe you do need a different speaker?
@tonyEE Ciao Tony, I am running the F4 with the SP9 as the BA3 preamp has an issue with hum and the guy who assembled it for me is very busy so I will have to wait to get it fixed, up and running to find out if the little extra gain does something but not to that great extent (little because as far as I have listened to it I can tell there is more gain but not to the extent not to make me feel bad about leaving the tubes amp in the dust).
Speaker wise the L220 sound very very nice with the KT88, 50W seem to be way enough to feed those, of course I thought of different speakers as these, as nice as they are, are big for my small space but am not in the position to trade with something else, got advise off the owner of some Audio Note AN- he said they are his definitive speakers (maybe as his definitive wife...) and that they would be a perfect match for this kind of amp but, money aside, I don't think I'd ever sell the L220, first and foremost I wanna make sure both the F4 and the BA3 match the project measurements (the F4 sure does as my friend also checked the waveform and said it's close to perfect).
I can't now remember the procedure to gain, with a DMM, the output of the preamp and/or the amp but once I get the BA3 fixed I want to measure both it and the SP9 to find out if the extra gain is there and how much it is.
Still thinking that I might, in the future and if I manage to make my ears like the F4 sound signature, put together another one and run the two bridged
Best
Speaker wise the L220 sound very very nice with the KT88, 50W seem to be way enough to feed those, of course I thought of different speakers as these, as nice as they are, are big for my small space but am not in the position to trade with something else, got advise off the owner of some Audio Note AN- he said they are his definitive speakers (maybe as his definitive wife...) and that they would be a perfect match for this kind of amp but, money aside, I don't think I'd ever sell the L220, first and foremost I wanna make sure both the F4 and the BA3 match the project measurements (the F4 sure does as my friend also checked the waveform and said it's close to perfect).
I can't now remember the procedure to gain, with a DMM, the output of the preamp and/or the amp but once I get the BA3 fixed I want to measure both it and the SP9 to find out if the extra gain is there and how much it is.
Still thinking that I might, in the future and if I manage to make my ears like the F4 sound signature, put together another one and run the two bridged
Best