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First One - mosFET amplifier module

fab

Member
Joined 2004
Paid Member
...
im stiil listening your amp VSSA VS GOLMUND Clone .

I have both amps and they have both very good sound. Although both of them are not original since I have modified them... I can not tell which one is better since they have both their strength. I would say that the VSSA have vocals range deeper in the soundstage and Goldmund is more upfront for vocals. They have other differences as well and the Goldmund has better current capability due to higher number of output Fets but my modified VSSA with PMI pcb uses double die MOSFET so it is not so different...:cool:

Fab
 
Speedskater, I would not claim anything like that, since every little damn thing influences amp's final performance. DF is just one among many very important details and as we all know where the devil is hiding we should not ignore any of them.

Please take a look to post #1 and see how many specs gained from measurements are present there and they are not even near to be completed.

Regards L.C. :cheers:

No that wasn't about you, Dick Pierce wrote that maybe 10 years ago about things that happened 10 years before that. Now it's just another hi-fi Urban Myth. So all amp manufactures have to include it in their specs.

********************************
That old Dick Pierce paper:

"Damping Factor: Effects On System Response"
Dick Pierce
Professional Audio Development

http://www.cartchunk.org/audiotopics/

http://www.audioholics.com/audio-amplifier/damping-factor-effects-on-system-response
 
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just added myself to the list... ;)

luca 4
danny_66 2
woofertester 4
rainerco 2
pinnocchio 4
giannettino 2
jokari69 2
mksung 2
ZZoran 2
Edgar 2
Eric06 2
kimon 2
maxidcx 2
e-bok 6
bobo le chat 2
metallicus69 6
scoutOne 4
Iduarte1973 2 (full kit)
quan 2
Greg Stewart 2
colesey 2
analogsa 4
Brianco 2
Theodosis O. 4
chunek 2
Darb 4 (full kit)
CaféNoir 4
Nikitas 2 (full kit)
meanman1964 2
supernet 2
jeremysk 2
Dane 2
mikvous 2
PreSapian 2
coolewater 2
edionysus 2 (full kit)
jaggel 2 (full kit)
 
luca 4
danny_66 2
woofertester 4
rainerco 2
pinnocchio 4
giannettino 2
jokari69 2
mksung 2
ZZoran 2
Edgar 2
Eric06 2
kimon 2
maxidcx 2
e-bok 6
bobo le chat 2
metallicus69 6
scoutOne 4
Iduarte1973 2 (full kit)
quan 2
Greg Stewart 2
colesey 2
analogsa 4
Brianco 2
Theodosis O. 4
chunek 2
Darb 4 (full kit)
CaféNoir 4
Nikitas 2 (full kit)
meanman1964 2
supernet 2
jeremysk 2
Dane 2
mikvous 2
PreSapian 2
coolewater 2
edionysus 2 (full kit)
jaggel 2 (full kit)
fredlock 2
 
Count me for 2 modules ;)

luca 4
danny_66 2
woofertester 4
rainerco 2
pinnocchio 4
giannettino 2
jokari69 2
mksung 2
ZZoran 2
Edgar 2
Eric06 2
kimon 2
maxidcx 2
e-bok 6
bobo le chat 2
metallicus69 6
scoutOne 4
Iduarte1973 2 (full kit)
quan 2
Greg Stewart 2
colesey 2
analogsa 4
Brianco 2
Theodosis O. 4
chunek 2
Darb 4 (full kit)
CaféNoir 4
Nikitas 2 (full kit)
meanman1964 2
supernet 2
jeremysk 2
Dane 2
mikvous 2
PreSapian 2
coolewater 2
edionysus 2 (full kit)
jaggel 2 (full kit)
fredlock 2
androuski 2
 
As promised yesterday here's the measurement result for 1 Wrms (2,83 Vrms)/8 Ohm at 1 kHz.

1. Input sine signal 0,11 Vrms, THD1k=4,8 ppm, best what I can get from the card's signal generator

2. Output signal 2,83 Vrms/8 Ohm, THD1k=16 ppm

As seen from plots, input signal artefacts generated by audio card faithfully transferred to the output plus some distortions added. With better input signal we could just get to single digit ppm. :cool:

Post #1 technical specifications updated according to measuring results. ;)

WOW

just WOW!!!

OK I want two of these with Roberto's SMPSs!!!

PS could we see the same measurement at 4 Ohm?
 
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Hi Eric

I would choose version 2, since it has the same IC and strong relay. Version 1 has also RLC filter which is not needed in our case, First One has it already.

First One has un-balanced (single ended) input, so if you would like to use your preamp's balanced output than I would suggest you to:
1. use Lundhal line transformer in between or
2. simply use just positive output referenced to GND or
3. use two First One modules per channel in full balanced configuration

Regards, L.C.


How well does it perform in configuration 3?

Have you considered a balanced version of the PCB/design specifically?
 
Hi LC,
many thanks for what you said, about the DPS-500, in practice it is the reality of the facts.
I can only offer the version DPS-500/DA at + /-52V. for other versions, buy on the shop AudioPower, as many already know, I certainly agreements but is not managed by me.

Congratulations for the excellent design and engineering of the PCB. :up:

Regards

What kinda price difference are we talking for diyaudio members for the DPS-500/DA at + /-52V vs. the shop?

Hey LC is 52V to high for a balanced setup?

Prob 45V max using two modules.
 
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Count me for 2 modules

luca 4
danny_66 2
woofertester 4
rainerco 2
pinnocchio 4
giannettino 2
jokari69 2
mksung 2
ZZoran 2
Edgar 2
Eric06 2
kimon 2
maxidcx 2
e-bok 6
bobo le chat 2
metallicus69 6
scoutOne 4
Iduarte1973 2 (full kit)
quan 2
Greg Stewart 2
colesey 2
analogsa 4
Brianco 2
Theodosis O. 4
chunek 2
Darb 4 (full kit)
CaféNoir 4
Nikitas 2 (full kit)
meanman1964 2
supernet 2
jeremysk 2
Dane 2
mikvous 2
PreSapian 2
coolewater 2
edionysus 2 (full kit)
jaggel 2 (full kit)
fredlock 2
androuski 2
HiroPro 2 (full kit)
 
Hey LC,

Can you post a photo of the FET side of the PCB as I'm curious how they would mount to chassis/heatsink. I take it the two holes near the VDC +/- is to mount PCB/FETs to a heatsink/chassis?

PS what are the other four holes center of C20/21 for?
 
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First One GB list update

Here's updated GB list:

luca 4
danny_66 2
woofertester 4
rainerco 2
pinnocchio 4
giannettino 2
jokari69 2
mksung 2
ZZoran 2
Edgar 2
Eric06 2
kimon 2
maxidcx 2
e-bok 6
bobo le chat 2
metallicus69 6
scoutOne 4
Iduarte1973 2 (full kit)
quan 2
Greg Stewart 2
colesey 2
analogsa 4
Brianco 2
Theodosis O. 4
chunek 2
Darb 4
CaféNoir 4
Nikitas 2 (full kit)
meanman1964 2
supernet 2
jeremysk 2
Dane 2
mikvous 2
PreSapian 2
coolewater 2
edionysus 2 (full kit)
jaggel 2 (full kit)
fredlock 2
androuski 2
HiroPro 2 (full kit)
darbost 2

No rush, at the moment PCB-s are in production process. :cool:

Thanks guys. :cheers:
 
WOW

just WOW!!!

OK I want two of these with Roberto's SMPSs!!!

PS could we see the same measurement at 4 Ohm?

Thanks, appreciate. :)

Will do in following days, quite busy at the moment.

How well does it perform in configuration 3?

Have you considered a balanced version of the PCB/design specifically?

For full-balanced version just mount two modules besides on the same heatsink, no dedicated PCB for this purpose.

Hey LC is 52V to high for a balanced setup?

Prob 45V max using two modules.

+/-45 V is optimal PSU for balanced version, +/-52 V is rather over the top.

Hey LC,

Can you post a photo of the FET side of the PCB as I'm curious how they would mount to chassis/heatsink. I take it the two holes near the VDC +/- is to mount PCB/FETs to a heatsink/chassis?

PS what are the other four holes center of C20/21 for?

All six holes needed to fix the module to the heatsink. Fixation holes and technical drawing will be a part of Installation manual included in the package, so no worries for the GB members. ;)

Regards, L.C. :)
 
Congrats L.C. One big success again.
May-i suggest you take contact with Roberto and Connex in order to get SMPS free samples, so you can make listening comparisons and report your experiences ?
If they are clever enough, and considering the success of this amp (only the beginning), i'm sure they will not lose the occasion to increase their sells if their products are good enough.

PS: I hope you had my email, your mail box had problems (a strange spam report) and i was not able to answer-you in the forum as i was baned for a while by the sensors.
 
Thanks, appreciate. :)

Will do in following days, quite busy at the moment.



For full-balanced version just mount two modules besides on the same heatsink, no dedicated PCB for this purpose.



+/-45 V is optimal PSU for balanced version, +/-52 V is rather over the top.



All six holes needed to fix the module to the heatsink. Fixation holes and technical drawing will be a part of Installation manual included in the package, so no worries for the GB members. ;)

Regards, L.C. :)

Six holes to mount it!!!

No problem with thermal coupling to the sink ehh!

LOL

Yeah it would be great to see a mechanical drawing so we could get DIY chassis sink taps made/ready for when this beauty ships.

I wonder if AP2 is willing to make a batch of 45V SMPSs for those of use considering going balanced...

I would place a rather large PCB production run order because if your measurements translate into the sonic returns we all think they will combined with Roberto's SMPS we'll have a $5K+ killer on our hands and at 88 Euros a singled ended channel, should sell like hotcakes.

You might just become the Bruno of A/B DIY modules LC and perhaps should consider full commercialization IE webshop etc.

I'm amazed what a simple low parts count surfacemount design can do.

What can you tell us about your ML air core inductor and Zr+Zc?

I'd sure love to see the backside of the gorgeous PCB.

I love those thick mil spec green PCBs.

I'm curious why you have the dual package FETs against the PCB. Would it not have been better to use it's legs and have it away from PCB for sink mounting?

Are they surfacemount?

DUDE

I gotta see the backside of that board!

LOL

I'm just an amateur and know little of EE amplifier design but I have a friend that would be very curious and could perhaps explain the design/operation to me in less technical terms.

I'd sure love to see the backside of that PCB with the output devices visible.
 
Here's updated GB list:

luca 4
danny_66 2
woofertester 4
rainerco 2
pinnocchio 4
giannettino 2
jokari69 2
mksung 2
ZZoran 2
Edgar 2
Eric06 2
kimon 2
maxidcx 2
e-bok 6
bobo le chat 2
metallicus69 6
scoutOne 4
Iduarte1973 2 (full kit)
quan 2
Greg Stewart 2
colesey 2
analogsa 4
Brianco 2
Theodosis O. 4
chunek 2
Darb 4
CaféNoir 4
Nikitas 2 (full kit)
meanman1964 2
supernet 2
jeremysk 2
Dane 2
mikvous 2
PreSapian 2
coolewater 2
edionysus 2 (full kit)
jaggel 2 (full kit)
fredlock 2
androuski 2
HiroPro 2 (full kit)
darbost 2
Turbon 2 (full kit)

Added myself for a complete kit. Should I PM as well?

Regards
 
First One GB list update

Added myself for a complete kit. Should I PM as well?

Regards

No PM necessary, post here is OK. ;)

One member from PM also added. :)

Here's latest update of GB list:

luca 4
danny_66 2
woofertester 4
rainerco 2
pinnocchio 4
giannettino 2
jokari69 2
mksung 2
ZZoran 2
Edgar 2
Eric06 2
kimon 2
maxidcx 2
e-bok 6
bobo le chat 2
metallicus69 6
scoutOne 4
Iduarte1973 2 (full kit)
quan 2
Greg Stewart 2
colesey 2
analogsa 4
Brianco 2
Theodosis O. 4
chunek 2
Darb 4
CaféNoir 4
Nikitas 2 (full kit)
meanman1964 2
supernet 2
jeremysk 2
Dane 2
mikvous 2
PreSapian 2
coolewater 2
edionysus 2 (full kit)
jaggel 2 (full kit)
fredlock 2
androuski 2
HiroPro 2 (full kit)
darbost 2
Turbon 2 (full kit)
r8833 2

Regards, L.C. :cheers:
 
I would place a rather large PCB production run order because if your measurements translate into the sonic returns we all think they will combined with Roberto's SMPS we'll have a $5K+ killer on our hands and at 88 Euros a singled ended channel, should sell like hotcakes.

You might just become the Bruno of A/B DIY modules LC and perhaps should consider full commercialization IE webshop etc.

I'm amazed what a simple low parts count surfacemount design can do.

I did, over k modules in production, so no worries about availability.

Low parts count doesn't neccessary mean low performance also measurements don't lie.

All technical details will be presented in installation manual besides module.

Regards, L.C. :cheers: