It is claimed now that FO v1.4 is leaps ahead of VSSA. Perhaps it is true. However the same was said of VSSA then compared to other Class AB amps.
I got an opportunity to test an original VSSA with Fostex FE168Sigmas in a MLTL. The bass was pathetic and the highs were shrill. The mids are forward and almost palpable, but tending towards sounding synthetic. Overall, very poor compared to all the praise showered by LC and many others. If FO v1.4 is a more refined amp in the same league as the VSSA, I am not in. Just my considered opinion.
I got an opportunity to test an original VSSA with Fostex FE168Sigmas in a MLTL. The bass was pathetic and the highs were shrill. The mids are forward and almost palpable, but tending towards sounding synthetic. Overall, very poor compared to all the praise showered by LC and many others. If FO v1.4 is a more refined amp in the same league as the VSSA, I am not in. Just my considered opinion.
Hi Sam
First One is not VSSA, also only if VSSA is paired with SMPS1200A180 it gives what was spoken about. We went quite a long way from it, First One v1.1-v1.3 and now we have First One v1.4 which has very little in common with previous versions, 33 semis in very complex CFA topology on 50 x 100 mm, now figure for yourself. My goal is evolution rather than starting from scratch every time and First One v1.4 definitely follows that path. Wait for v1.4 reviews and if by chance intrigued then decide whether to buy or not.
For more demanding low Z speakers FO v1.4 L will be lounched soon, not to forget FO v1.4 S for small active speakers too.
First One is not VSSA, also only if VSSA is paired with SMPS1200A180 it gives what was spoken about. We went quite a long way from it, First One v1.1-v1.3 and now we have First One v1.4 which has very little in common with previous versions, 33 semis in very complex CFA topology on 50 x 100 mm, now figure for yourself. My goal is evolution rather than starting from scratch every time and First One v1.4 definitely follows that path. Wait for v1.4 reviews and if by chance intrigued then decide whether to buy or not.
For more demanding low Z speakers FO v1.4 L will be lounched soon, not to forget FO v1.4 S for small active speakers too.
Hi LC,
For speakers with 3ohm dip,
which SMPS do you suggest for the v1.4M, SMPS1200A180 2x45V or SMPS1200A400 2x65V ?
Regards,
Danny
I hope this doesn't pollute the thread too much but it may help other's if they encounter similar problems with multi amp setups.
I thought that by connecting the SMPS ground to one single cable shield I was connecting the output signal ground from the active crossover to the amps main ground point.
I would not also connect this to the input pad on the first one. There would then be one direct connection between SMPS ground in the amp and output signal ground on the active crossover. I would then make sure the interconnects only has the positive input signal as you say
If this isn't what you are describing then I think I am misunderstanding what you mean by output ground
also
This is certainly not true of any of the First One amps. I have not heard the VSSA so I can't compare but the First One amps have no issues with the quality or quantity of bass and have smooth treble. There will always be personal preferences but I doubt anyone would be disappointed with a First One amp unless they thought it would cure cancer or something equally unlikely
Thanks
I can see why they would not be the ideal solution. Can you explain why they won't do?
I thought that by connecting the SMPS ground to one single cable shield I was connecting the output signal ground from the active crossover to the amps main ground point.
I would not also connect this to the input pad on the first one. There would then be one direct connection between SMPS ground in the amp and output signal ground on the active crossover. I would then make sure the interconnects only has the positive input signal as you say
If this isn't what you are describing then I think I am misunderstanding what you mean by output ground
also
This is certainly not true of any of the First One amps. I have not heard the VSSA so I can't compare but the First One amps have no issues with the quality or quantity of bass and have smooth treble. There will always be personal preferences but I doubt anyone would be disappointed with a First One amp unless they thought it would cure cancer or something equally unlikely
Thanks
SMPS1200A400 if speakers have less than 96 dB/W/m
SMPS1200A180 if speakers have more than 96 dB/W/m
Explanation why neither would do:I can see why they would not be the ideal solution. Can you explain why they won't do?
I thought that by connecting the SMPS ground to one single cable shield I was connecting the output signal ground from the active crossover to the amps main ground point.
1. Not a good practice since FO channels wouldn't have equal GND path/resistance. Avoid GND connections via shielding of a cable (RFI antenna, low-pass filter effect, etc.), rather use solid core wire from reference GND point of an active crossover to GND reference point of an amp's SMPS, by this way you'll form the most direct GND to GND low Z connection.
2. Again no symmetry for FO amps, different GND paths - interference curents may appear
Seems very frustrating for some people who's never tasted First One like to make comments about SQ solely based on assumptions. Now that has only two logical explanations, whether they have very rich imagination or they wish to spread bad publicity to make some harm.This is certainly not true of any of the First One amps. I have not heard the VSSA so I can't compare but the First One amps have no issues with the quality or quantity of bass and have smooth treble. There will always be personal preferences but I doubt anyone would be disappointed with a First One amp unless they thought it would cure cancer or something equally unlikelySamuel said:
Thanks
FO v1.4 S + SMPS1200A180 would give 75 Wrms/8 Ohm, not a thunderstorm but with efficient speakers this would do just fine.
The FO 1.2/1.3 is slightly improved in all these areas. Bass however is still seriously lacking in comparison to an even modest bipolar class AB using the same PS.
Perhaps people have widely different interpretation of what is decent bass or a natural tonality.
Sound reproduction is always a question of compromise too. Would you rather have a tonally neutral amp or one which is exciting and has dynamic freedom?
LC thanks for the info and I see what you mean. I was hoping for a solution that would not involve having to work on the chassis but it seems that won't be possible.
I can add a connector of some sort to the back panel of each chassis so the grounds can be connected directly with a solid or thicker gauge wire.
I have attached a picture of the insides of the crossover. There is a 5V and +/-12V power supply. The 5V is mainly for the digital components and the 12V is mainly for the opamps on the output buffers. I would imagine that either of these power ground points where they attach to the main black board would be the best place to join the ground from the smps?
Attachments
FO v1.4 S + SMPS1200A180 would give 75 Wrms/8 Ohm, not a thunderstorm but with efficient speakers this would do just fine.
Ok, on my 3 ways speakers the woofer is a 10" 90db sealed cut at 60Hz 8ohm. So the 10" don't play on his impedance pike. Do you thinks that is enough?
It depends how loud you're listening, max SPL of the speakers, etc., but in general that's enough for small to mid sized rooms. SOAR of the outputs is not in danger zone because of your speaker's load.
OK since an active crossover is in the other chassis, solution is to connect all GND points of input RCA connectors in amp chassis together and lead only one wire to central GND of amp's SMPS. Positive wires from input RCA to + IN pad of each channel.
Thanks. That is a much simpler and easier idea. I will give it a go and see what happens.
It is very frustrating for some people to evaluate a product only relying on marketing comments from the manufacturer about their SQ.
Without a theoretical schematic, and a full set of measurements, i will never order any piece of electronic equipment. Never. Now that has only two logical explanations, whether the manufacturer require a blind confidence from future customers, for any strange psychological reasons, or the manufacturer wish to hide some issues.
As I said in post #2043:
No forcing anybody here to buy anything, as already said wait for many different reviews. This time for me the task is much easier than the first time since people will be more careful so less orders at start will give me more time to handle GB in more lightweight way.
Dear Esperado I'm not stupid to give fine tuned FO CFA schematic on the net for free, some would even like to publish PCB gerbers hehe. This is the real World, c'mon.
They can only wish.
