Hmm, it seems like your SP9 ought to swing enough voltage? I guess that with 2 Vrms input it ought to put out 20 Vrms output, at full volume...
SP9:
RATED OUTPUTS
2V RMS 5Hz to 50kHz, all outputs; 60K ohm load (main output capability is 50 V RMS output at 1/2% THD at 1kHz into a 100K ohm load with 5V RMS high level input)
GAIN
SP9: Phono input to tape output: 46dB. Phono input to main output: 66dB. High level inputs to tape output: 0dB. High level inputs to main output: 20dB. SP9 MKII/III: Phono input to tape output: 46dB. Phono input to main output: 67dB. High level inputs to tape output: 0dB. High level inputs to main output: 21dB. CD input to main output: 9dB.
https://www.arcdb.ws/model/SP9
https://www.stereophile.com/content/audio-research-sp9-preamplifier-specifications
SP9:
RATED OUTPUTS
2V RMS 5Hz to 50kHz, all outputs; 60K ohm load (main output capability is 50 V RMS output at 1/2% THD at 1kHz into a 100K ohm load with 5V RMS high level input)
GAIN
SP9: Phono input to tape output: 46dB. Phono input to main output: 66dB. High level inputs to tape output: 0dB. High level inputs to main output: 20dB. SP9 MKII/III: Phono input to tape output: 46dB. Phono input to main output: 67dB. High level inputs to tape output: 0dB. High level inputs to main output: 21dB. CD input to main output: 9dB.
https://www.arcdb.ws/model/SP9
https://www.stereophile.com/content/audio-research-sp9-preamplifier-specifications
Yes, that should be the gain figure and I can tell, the little I used the BA3, there was more gain but I'd like to quantify with a test to find out the real gain difference, I seem to recall feeding a 1Khz sine to the preamp and then measure the AC output on the RCA but not sure about the procedure
You need to measure the input signal (from the source) as well.
AC out / AC in = AC Gain
AC out / AC in = AC Gain
Hello folks,
long time not on DIY and longer time the F4 and BA3 collect dust and before my busy season comes I have to think of a solution for them, now listening to the AR SP9 and KT88, it's ok, I like tube sound but I have to decide what to do with the solid state.
I'd like to know how to figure what's the output out of both the SP9 and BA3 to find out if I am driving the F4 to its fullest output or if I am limiting it to, as somebody pointed out along the thread, to 50% of its capability, how do I check given I only have a DMM (can borrow another one) and can input a signal through my MacBookAir straight onto the preamp?
A solution could be to go balanced with the BA3, can buy one more PCB, look out for the FETs and ask my friend to modify the already done preamp and turn it into balanced and also modify the F4 to make it capable of balanced input (just as a remainder it was built as full dual mono with twin transformers), the other solution would be to build another F4 same as the one I already have, way more expensive and time consuming but as of today I won't know what to do with them as they are, changing speakers would be a blind and very expensive date.
Any suggestion is welcome and sorry for ripping more space and time
Giovanni
p.s. dunno if I wrote about it along the thread but the F4 has been fixed and biased, a few min after switch on it warms up and even tho the preamp doesn't push it to full potential I can tell it works as it should and the couple is dead silent, no any noise, no hum no anything...
long time not on DIY and longer time the F4 and BA3 collect dust and before my busy season comes I have to think of a solution for them, now listening to the AR SP9 and KT88, it's ok, I like tube sound but I have to decide what to do with the solid state.
I'd like to know how to figure what's the output out of both the SP9 and BA3 to find out if I am driving the F4 to its fullest output or if I am limiting it to, as somebody pointed out along the thread, to 50% of its capability, how do I check given I only have a DMM (can borrow another one) and can input a signal through my MacBookAir straight onto the preamp?
A solution could be to go balanced with the BA3, can buy one more PCB, look out for the FETs and ask my friend to modify the already done preamp and turn it into balanced and also modify the F4 to make it capable of balanced input (just as a remainder it was built as full dual mono with twin transformers), the other solution would be to build another F4 same as the one I already have, way more expensive and time consuming but as of today I won't know what to do with them as they are, changing speakers would be a blind and very expensive date.
Any suggestion is welcome and sorry for ripping more space and time
Giovanni
p.s. dunno if I wrote about it along the thread but the F4 has been fixed and biased, a few min after switch on it warms up and even tho the preamp doesn't push it to full potential I can tell it works as it should and the couple is dead silent, no any noise, no hum no anything...
All I know about Capri is that we got really sick on the ferry ride from Napoli.. and the tide was too high that day so we couldn't get to the caves.
Nice town though.
Good enough for the Emperors.
I checked with Audio Research about their preamps. I believe they go as high as 10Vrms, that's it. Not enough to truly swing the F4 unless you got very efficient speakers. I was thinking of getting one of their SE units, but ended up with a Conrad Johnson ET3SE which swings a full 20Vrms. That is more than sufficient to make the F4 sing. I had the setup driving 90sb/w speakers.... and that sounded very, VERY good.
Nice town though.
Good enough for the Emperors.
I checked with Audio Research about their preamps. I believe they go as high as 10Vrms, that's it. Not enough to truly swing the F4 unless you got very efficient speakers. I was thinking of getting one of their SE units, but ended up with a Conrad Johnson ET3SE which swings a full 20Vrms. That is more than sufficient to make the F4 sing. I had the setup driving 90sb/w speakers.... and that sounded very, VERY good.
Don't tell me @tonyEE I just got back off a short journey to the US and once landed in Napoli the ride to the docks and then a 40 years old catamaran to get to Capri with rough seas was the worst part of a journey which was worth an Indiana Jones movie, I think many people here talk nonsense, they talk about third world but have no clue how advanced some countries down there are compared to us, they travel but they only see the leisure side or their journeys and once back home they don't realise how bad conditions are on this island...
20Vrms preamp, I guess I have to find a tube DIY project, I forgot how to measure the preamp output, sine wave input, volume knob to the max and measure DC out? I wanna figure how many V coming out of the BA3 I got assembled
Grazie
20Vrms preamp, I guess I have to find a tube DIY project, I forgot how to measure the preamp output, sine wave input, volume knob to the max and measure DC out? I wanna figure how many V coming out of the BA3 I got assembled
Grazie
1K sine wave input set to nice round figure (set with your DM set to Vac), volume knob to the max and measure Vac out with same DVM
then just calc ratio of those
db = 20*log(Vout/Vin)
I just measured the SP9 output, gave it a 1Khz sine wave through my MacBookAir out of the headphones jack, max volume on the MBAir and looped the tune, reported 3.25VAC, switched to the DAC output, gave it the same sine wave and measured again on the end of the signal cable connecting the SP9 to the power amp, this time 3.1VAC.
I got 3.9VAC out of the BA3.
Out of ZenMod equation I miss the Vin value, have no clue where to retrieve that data, I guess this is the output on the headphone connector of my MacBookAir.
Grazie
Welcome back!
Do you need it to be louder when you have the volume turned completely to maximum? What are you trying to determine?
Measure output of MacBook. That is Input to Preamp. ... or just calculate.
Stop using the MB as the source if you are trying to get maximum ouput from the pre-amp. It won't do it. Typical gain of the SP9 (high to high) is 20dB. Assuming that's what you're using...
3Vxx out is 0V3xx in.
Your MacBook is meant to be used with headphones not as a line source / input to a preamplfier. It will work fine, but that's not a typical use. It just won't put out the voltage you seem to want.
A digital source with a 0dBFS input will typically put out ~2Vxx (6 times the output of your MacBook HP output) as an example. If you use a 'proper' source vs. your MacBook and use a high signal level...
2Vxx X10 (20dB gain) is 20Vxx.... and yes, that will result in a typical F4 voltage clipping.
If you want it louder, then the issue is the MacBook. Not the amp, not the pre-amp.
Ciao @ItsAllInMyHead and grazie for the welcome back!!!
I am trying to determine if the BA3 is delivering full potential to drive the F4 as I have issues with BA3 + F4 + JBL L220 and as such I wanna figure the output voltage of both the SP9 and the BA3 to try and find out the gain out of both and if there is any issue with the BA3.
What would you suggest to use to input the sine 1Khz wave into either the DAC and then preamp or straight into preamp to then retrieve the output voltage?
I only have available a CD player, which means I'll have to burn a CD with the 1Khz test signal, MacBookAir, MacMini, iPod...
I don't want it louder, I am just trying to figure the gain of both the SP9 and the BA3, while the SP9 is supposed to output about 10V which are not enough to drive the F4 to full throttle I wanna try and figure the gain of the BA3 and understand if something is wrong with it as the gain, by the ear, vs the SP9 is just marginal while it is supposed to be way higher.
Grazie
I am trying to determine if the BA3 is delivering full potential to drive the F4 as I have issues with BA3 + F4 + JBL L220 and as such I wanna figure the output voltage of both the SP9 and the BA3 to try and find out the gain out of both and if there is any issue with the BA3.
What would you suggest to use to input the sine 1Khz wave into either the DAC and then preamp or straight into preamp to then retrieve the output voltage?
I only have available a CD player, which means I'll have to burn a CD with the 1Khz test signal, MacBookAir, MacMini, iPod...
I don't want it louder, I am just trying to figure the gain of both the SP9 and the BA3, while the SP9 is supposed to output about 10V which are not enough to drive the F4 to full throttle I wanna try and figure the gain of the BA3 and understand if something is wrong with it as the gain, by the ear, vs the SP9 is just marginal while it is supposed to be way higher.
Grazie
^ I think I see the gap in understanding / my communication. My apologies.
You measured all that is necessary. Let me try another way to explain. Let us start from the F4.
Assume you need 14V to achieve maximum output of your F4. Again... don't worry about Watts or Current for this demonstration.
Since F4 has no voltage gain, you need to have 14V input to the F4.
You measured 3VXX from both the SP9 and the BA-3 when using your MacBook as the input source to the pre-amplifiers.
So... you know that you are not getting maximum output from the F4. Finished. Your question is answered.
-------------
SP9 CAN output up to 50V IF you feed the input 5V. Again, gain is 20dB => 10X From the manual...
You are not feeding the input to the pre-amp enough voltage => Your MacBook cannot do it. This was answered previously in the thread linked below.
See previous conversation over here...
https://www.diyaudio.com/community/...eamp-build-guide.258022/page-143#post-7371771
Both of them have roughly the same gain... IF you are using the inputs you say on the SP9MKII AND if previous measurements on your BA-3 are the same.
Everything seems to be in order.
Any other questions?
You measured all that is necessary. Let me try another way to explain. Let us start from the F4.
Assume you need 14V to achieve maximum output of your F4. Again... don't worry about Watts or Current for this demonstration.
Since F4 has no voltage gain, you need to have 14V input to the F4.
You measured 3VXX from both the SP9 and the BA-3 when using your MacBook as the input source to the pre-amplifiers.
So... you know that you are not getting maximum output from the F4. Finished. Your question is answered.
-------------
SP9 CAN output up to 50V IF you feed the input 5V. Again, gain is 20dB => 10X From the manual...
You are not feeding the input to the pre-amp enough voltage => Your MacBook cannot do it. This was answered previously in the thread linked below.
See previous conversation over here...
https://www.diyaudio.com/community/...eamp-build-guide.258022/page-143#post-7371771
Both of them have roughly the same gain... IF you are using the inputs you say on the SP9MKII AND if previous measurements on your BA-3 are the same.
Everything seems to be in order.
Any other questions?
Ok @ItsAllInMyHead and @nicoch58 sources wise I either use the DAC, which I rather not, a CD player (it has both fixed and variable output but when I sent it to upgrade the variable output has been disabled and I can't figure how to restore it, if I could I would throw the CD variable output right into the F4 to figure it out), iPod, iPad, MacBookAir, MacMini... only real hifi source being the Sony CD-X505ES.
Should I burn a CD with test tracks and re-measure with the CD player as a source on both the SP9 and the BA3?
Grazie
Should I burn a CD with test tracks and re-measure with the CD player as a source on both the SP9 and the BA3?
Grazie
I am having trouble understanding what more you want to do.
Both pre-amps seem to be functioning properly.
The amplifier seems to be functioning properly.
You know the gain of all the equipment through your measurements, and it aligns with expectations.
There is no need to do anything further. All your questions have been answered, I think. No need for any other measurements unless it is fun for you.
If you want it louder, which you say you do not, then you can use a CD player or something other than your MacBook as your source. If you like the MacBook, and if it is loud enough, then keep using it.
Both pre-amps seem to be functioning properly.
The amplifier seems to be functioning properly.
You know the gain of all the equipment through your measurements, and it aligns with expectations.
There is no need to do anything further. All your questions have been answered, I think. No need for any other measurements unless it is fun for you.
If you want it louder, which you say you do not, then you can use a CD player or something other than your MacBook as your source. If you like the MacBook, and if it is loud enough, then keep using it.