Atention...this is great, my friend Dragon2, experienced Canadien is observing GEM
performance very close...with the aid of instruments and A to B comparison...the research has more than 10 days when he started with the idea.
Well, you know that Dragon spit fire!
This Canadien, 2 meters tall man, those that can enter a competition to cut enormous threes.... with a hand axe...the red man, as his face is red so hot he is.... will use the justice hammer and will finish with all the Myths... the damn, terrible, clear, cold, reality will appear.
Another Canadien told me that he was fishing when a bear appeared...was not an adult... a teenager bear...tried to attack him and he punch the one that run out very fast (I do not believe... the other Canadien may be lying!)
JLH versus GEM
By a more than 40 years experience technician that expend all life repairing audio amplifiers, a hobbyist and a professional... already doing it... daily going to job and fixing the amplifier our friends burn (ahahah!).
If something bad...he promissed to smash!... to pulverize and to spitfire in every defect.
I am waiting his evaluation... and a little afraid...of course.
Because nothing is perfect in this world, if the man really entered to search for defects.... he may have sucess.... i am shacking my bonds... Spitfire ... the Justicer Dragon is coming!
Of course kidding boys!..he is a sweet and family man, not violent and that one that cares family and read books...he will produce a very fair analisis.
regards,
future Charlotte.... ex Big fat Charles
performance very close...with the aid of instruments and A to B comparison...the research has more than 10 days when he started with the idea.
Well, you know that Dragon spit fire!
This Canadien, 2 meters tall man, those that can enter a competition to cut enormous threes.... with a hand axe...the red man, as his face is red so hot he is.... will use the justice hammer and will finish with all the Myths... the damn, terrible, clear, cold, reality will appear.
Another Canadien told me that he was fishing when a bear appeared...was not an adult... a teenager bear...tried to attack him and he punch the one that run out very fast (I do not believe... the other Canadien may be lying!)
JLH versus GEM
By a more than 40 years experience technician that expend all life repairing audio amplifiers, a hobbyist and a professional... already doing it... daily going to job and fixing the amplifier our friends burn (ahahah!).
If something bad...he promissed to smash!... to pulverize and to spitfire in every defect.
I am waiting his evaluation... and a little afraid...of course.
Because nothing is perfect in this world, if the man really entered to search for defects.... he may have sucess.... i am shacking my bonds... Spitfire ... the Justicer Dragon is coming!
Of course kidding boys!..he is a sweet and family man, not violent and that one that cares family and read books...he will produce a very fair analisis.
regards,
future Charlotte.... ex Big fat Charles
Attachments
Comparing GEM and JLH
Hi everybody.
Carlos, you are very kind and i suspect you to be a kind of amplifier too...Ha! HA! very kind indeed...
As you said Carlos, It take time to compare.
This time i have compared an updated JLH (schematic) with GEM.
The JLH is fitted Motorola MJ15003 at output, 2SC3421 as driver and 2SC970 as input transistor. I have cranked the bias at 2,5 amp so it run hot. Nothing was changed because it is the reference unit.
On the GEM, i have tried 3 different output transistors, two different drivers transistors and two different at input/current mirror.
I have used one channel only of JLH with speakers in parallell to be mono like GEM.
I have checked amplifiers power/frequency response with square waves to see oscillations. As measuring do not give clues on sound, i just checked to see if amplifier worked properly.
We were three to listen sometime but i was often alone because it is a long work.
JLH: very good, soft and detailled sound. Smooth on highs.
If you crank bias, it is better in controling bass. Very pleasant to listen on long runs. Not too bad with less than good recording.
Something difficult to describe when we listen to this amp: a little magic in it. Not perfect, a little coloration in sound (pleasant?)
Tireless unit.... Genius unit!
Usefull in Canada: heating the room...
The GEM with MJ15003(output) MJE172/182 (drivers/VAS/Bias)
MPSA06/56 (input/current source).
Stable: no oscillations.
Great bass control, good midrange and good highs.
A little tiring on long runs. Very sensible to recording.
Sound very good on good recordings.(rare)
I don't know why but seems less dynamic than JLH. The three listeners agree with that.
I have cleared the 0.1 ohm resistors just to see if amplifier sound change. Bass is better controlled!!! Mid and highs a little bit more transparent... More dynamic! Curious thing for an amp with so much feedback the effect of those little value resistors....
This is the best transistors arrangement for bass.
I replaced the input /current s. transistors and the amp tend to oscillate. (2SC2240/2SA970)I had to move wiring to stop that. Need better construction! Sound become more transparent so i keeped those. Bass is less good: more airy, less punch/control. Why?those transistors have higher hfe and are more linear so they should be better....
I have replaced drivers/Vas/bias transistors with 2SC3421/2SA1358 and oscillation tendency is gone.
Improving midrange and high: liquid midrange, a little hard on high on long runs too... Very precise amplifier! We need better recordings....
Finally i have replaced output transistors with the Carlos prefered ones: Sanken 2SC2922/2SA1216. (With emitter resistors removed.)
More transparent, better mid than MJ15003, more airy highs.
A good balance! Bass is less good than with the Motorolas...
A little tiring on high . Dynamic like the Motorolas.
Bad recordings are more disturbing with the Sankens.
Good recording are overall better with these ones.
Sibilant on occasion. (on a recording i am listening often with another amp and i have not this problem)
Changing the Sankens for Toshibas 2SA1302/2SC3281.
Installing 0.1 ohm resistors and 5 transistors...
Board is becoming a mess....
The better for midrange and high. Better bass than Sankens!
I don't know why! Better dynamics than Motorolas and Sankens!
Why?
The more detailled version: outstanding on good recordings.
Very precise amplifier. You will need good source and good speakers: not too agressive= this amp is fast!
Stay a little tiring on highs on long run.
I have adjusted bias as recommended by Graham: touchy ajustments.
I have ajusted bias to 1 amp class A and to 250 ma class AB and all versions become smoother but produce a lot of heat: i had to put a fan.
A very good design and outstanding performer if you use good recordings. Not as tolerant as JLH. Graham has told me that before.
Thanks Graham for a so good design.
Thanks Carlos for help and jokes!!
Thanks Barryblue for board design: it will help to construct neat boards: mine was constructed on copper side of universal board.
I must say that i have ring tweeters so this may have not helped with that kind of amp.
I use feedbackless amp on these speakers and they sound very good, very fast and not hard.
Hope this "reporting" will help those who want to build this amplifier. This is a very precise amplifier! Hope recording will be better in the future... The pleasant amp are not necessary the more precise ones!!!
Carlos, we will not call you "Charlotte" !!
Hi everybody.
Carlos, you are very kind and i suspect you to be a kind of amplifier too...Ha! HA! very kind indeed...
As you said Carlos, It take time to compare.
This time i have compared an updated JLH (schematic) with GEM.
The JLH is fitted Motorola MJ15003 at output, 2SC3421 as driver and 2SC970 as input transistor. I have cranked the bias at 2,5 amp so it run hot. Nothing was changed because it is the reference unit.
On the GEM, i have tried 3 different output transistors, two different drivers transistors and two different at input/current mirror.
I have used one channel only of JLH with speakers in parallell to be mono like GEM.
I have checked amplifiers power/frequency response with square waves to see oscillations. As measuring do not give clues on sound, i just checked to see if amplifier worked properly.
We were three to listen sometime but i was often alone because it is a long work.
JLH: very good, soft and detailled sound. Smooth on highs.
If you crank bias, it is better in controling bass. Very pleasant to listen on long runs. Not too bad with less than good recording.
Something difficult to describe when we listen to this amp: a little magic in it. Not perfect, a little coloration in sound (pleasant?)
Tireless unit.... Genius unit!
Usefull in Canada: heating the room...
The GEM with MJ15003(output) MJE172/182 (drivers/VAS/Bias)
MPSA06/56 (input/current source).
Stable: no oscillations.
Great bass control, good midrange and good highs.
A little tiring on long runs. Very sensible to recording.
Sound very good on good recordings.(rare)
I don't know why but seems less dynamic than JLH. The three listeners agree with that.
I have cleared the 0.1 ohm resistors just to see if amplifier sound change. Bass is better controlled!!! Mid and highs a little bit more transparent... More dynamic! Curious thing for an amp with so much feedback the effect of those little value resistors....
This is the best transistors arrangement for bass.
I replaced the input /current s. transistors and the amp tend to oscillate. (2SC2240/2SA970)I had to move wiring to stop that. Need better construction! Sound become more transparent so i keeped those. Bass is less good: more airy, less punch/control. Why?those transistors have higher hfe and are more linear so they should be better....
I have replaced drivers/Vas/bias transistors with 2SC3421/2SA1358 and oscillation tendency is gone.
Improving midrange and high: liquid midrange, a little hard on high on long runs too... Very precise amplifier! We need better recordings....
Finally i have replaced output transistors with the Carlos prefered ones: Sanken 2SC2922/2SA1216. (With emitter resistors removed.)
More transparent, better mid than MJ15003, more airy highs.
A good balance! Bass is less good than with the Motorolas...
A little tiring on high . Dynamic like the Motorolas.
Bad recordings are more disturbing with the Sankens.
Good recording are overall better with these ones.
Sibilant on occasion. (on a recording i am listening often with another amp and i have not this problem)
Changing the Sankens for Toshibas 2SA1302/2SC3281.
Installing 0.1 ohm resistors and 5 transistors...
Board is becoming a mess....
The better for midrange and high. Better bass than Sankens!
I don't know why! Better dynamics than Motorolas and Sankens!
Why?
The more detailled version: outstanding on good recordings.
Very precise amplifier. You will need good source and good speakers: not too agressive= this amp is fast!
Stay a little tiring on highs on long run.
I have adjusted bias as recommended by Graham: touchy ajustments.
I have ajusted bias to 1 amp class A and to 250 ma class AB and all versions become smoother but produce a lot of heat: i had to put a fan.
A very good design and outstanding performer if you use good recordings. Not as tolerant as JLH. Graham has told me that before.
Thanks Graham for a so good design.
Thanks Carlos for help and jokes!!
Thanks Barryblue for board design: it will help to construct neat boards: mine was constructed on copper side of universal board.
I must say that i have ring tweeters so this may have not helped with that kind of amp.
I use feedbackless amp on these speakers and they sound very good, very fast and not hard.
Hope this "reporting" will help those who want to build this amplifier. This is a very precise amplifier! Hope recording will be better in the future... The pleasant amp are not necessary the more precise ones!!!
Carlos, we will not call you "Charlotte" !!
Attachments
My dear friend Gilles, the kind Dragon, i thank you to show us how is a good
comparative A to B fair listening testing.
The clear and fair analisis...i was surprised with some details you perceived related the Sankens.
Astonished you get exactly what i felt here... a very good, really fair analisis.
I expect Dimitris are reading all your words, he is our forum friend, from Greece and made some evaluations too...again JLH was the reference amplifier to judgement.
I have to say that my mouth was openned with the expression of surprise, as i thougth i was good related that kind of work.....no, i am not!
Have to say..... i am feeling a little bit sad.... as i have discovered i am worst than you... the dirty envy feeling had invaded my heart for some moments...but i can see, as i have you as my personal friend, with personal mails going and returning, when we show our lives one each other, that i can understand you as someone that will ADD value to my person, as you have full conditions to sign under my ideas, the same way a more experienced superviser can sign under some design.
Well Monsieur, have to say that i was waiting for less than that, all the competence i could perceive on you was less than you show... i am completely surprised, as you are humble and came interested to have conversations with someone so less capable than you are!
Ahahahaha!...may be because i am an amplifier, you are rigth, Mum already told me when i was younger and she was alive, that i use to produce some tragedies when things goes wrong, and to put a little condiment in some food that have any salt.... the exagerating capacity, some excess of enthusiasm....i agree with you...you got it!
I am printing to read it again and again..... and this will be done to learn!...you will see, near future, i will use your analisis system...Yeah!.... will copy your good work, as i cannot dennie it is better than i could do...will follow the master!
Happy to scape to be called Charlotte...as i guarantee this amplifier and i have put my honor on it!
Of course it is not perfect..... JLH is not perfect too...but they are less strange than many others...then thousand of others!
When we go out, to listen to alive music...we see that we are distant from the reality..... as our sound reproduction is so fake as sinthetic Mango juice, can be delicious...but a damn fake!
Many times alive reproduction is much worst than recordings.... there are children crying...dogs making noise...airplanes crossing the air...wind...transit...people talking...echos and many things...and all those "noises" are the real world sound.... the studio remove all those noises...hehe.... producing filtered sinthetic things.... afraid to be ridiculous, they produce something that is ridiculous when we go to listen alive music.
Do you know bambôo.... that Asian very resistant wood...tubular wood, with some air inside...with enormous mechanic capacity to increase construction resistance..... the one when crashed...cracked... beeing near music, start to produce a ressonance that a called the bamboo vibration...this is present in some instruments... alike Saxophone, and not all amplifiers are capable to show that detail as JLH can do... some ressonances, graspy and harshing sound that some instruments produce.... natural sound..... violin can be very strange depending the amplifier and piano is the class D killer!
My respects and congratulations Mr. Gilles...proud that you are a friend, i may be interesting to have people alike you having interest on me...i feel good with that.
You can read all forum, i am sure you did it...jumping parts, as you have not so big spare time as i have.... no one could make some analisis so clear than you made.
The analist!
regards,
Carlos
comparative A to B fair listening testing.
The clear and fair analisis...i was surprised with some details you perceived related the Sankens.
Astonished you get exactly what i felt here... a very good, really fair analisis.
I expect Dimitris are reading all your words, he is our forum friend, from Greece and made some evaluations too...again JLH was the reference amplifier to judgement.
I have to say that my mouth was openned with the expression of surprise, as i thougth i was good related that kind of work.....no, i am not!
Have to say..... i am feeling a little bit sad.... as i have discovered i am worst than you... the dirty envy feeling had invaded my heart for some moments...but i can see, as i have you as my personal friend, with personal mails going and returning, when we show our lives one each other, that i can understand you as someone that will ADD value to my person, as you have full conditions to sign under my ideas, the same way a more experienced superviser can sign under some design.
Well Monsieur, have to say that i was waiting for less than that, all the competence i could perceive on you was less than you show... i am completely surprised, as you are humble and came interested to have conversations with someone so less capable than you are!
Ahahahaha!...may be because i am an amplifier, you are rigth, Mum already told me when i was younger and she was alive, that i use to produce some tragedies when things goes wrong, and to put a little condiment in some food that have any salt.... the exagerating capacity, some excess of enthusiasm....i agree with you...you got it!
I am printing to read it again and again..... and this will be done to learn!...you will see, near future, i will use your analisis system...Yeah!.... will copy your good work, as i cannot dennie it is better than i could do...will follow the master!
Happy to scape to be called Charlotte...as i guarantee this amplifier and i have put my honor on it!
Of course it is not perfect..... JLH is not perfect too...but they are less strange than many others...then thousand of others!
When we go out, to listen to alive music...we see that we are distant from the reality..... as our sound reproduction is so fake as sinthetic Mango juice, can be delicious...but a damn fake!
Many times alive reproduction is much worst than recordings.... there are children crying...dogs making noise...airplanes crossing the air...wind...transit...people talking...echos and many things...and all those "noises" are the real world sound.... the studio remove all those noises...hehe.... producing filtered sinthetic things.... afraid to be ridiculous, they produce something that is ridiculous when we go to listen alive music.
Do you know bambôo.... that Asian very resistant wood...tubular wood, with some air inside...with enormous mechanic capacity to increase construction resistance..... the one when crashed...cracked... beeing near music, start to produce a ressonance that a called the bamboo vibration...this is present in some instruments... alike Saxophone, and not all amplifiers are capable to show that detail as JLH can do... some ressonances, graspy and harshing sound that some instruments produce.... natural sound..... violin can be very strange depending the amplifier and piano is the class D killer!
My respects and congratulations Mr. Gilles...proud that you are a friend, i may be interesting to have people alike you having interest on me...i feel good with that.
You can read all forum, i am sure you did it...jumping parts, as you have not so big spare time as i have.... no one could make some analisis so clear than you made.
The analist!
regards,
Carlos
Hi All,
Have been busy using my limited capabilities to paint up Mum's day room whilst she was in hospital due to a blocked upper bowel. It could be that the codeine based pain killers she was on had actually caused this !!!!
Now she is home again and trying to get over her additional ordeal.
Meanwhile I am trying to catch up on other things I could not get done, and presently, audio is not on the list.
Hi Dragon 2.
Yes the GEM is capable of revealing bad source material and CD player equipment that can be 'grainy' or less accurate on transients. Also as Carlos has hinted, it will even make loudspeakers reproduce differently - as do ALL different NFB loop controlled amplifiers.
See for interest;-
http://www.prorec.com/prorec/articles.nsf/articles/8A133F52D0FD71AB86256C2E005DAF1C
The GEM would probably be best driven by dedicated DACs like the Benchmark or an AQVOX-USB 2 D/A.
Where this is not possible then fractional input hf roll-off filtering could be empirically adjusted to set up a satisfactory reproduction characteristic, and the second version of the JLH class-A already has such input filtering. This can subjectively improve reproduction by 'taking the edge' off *distorted* source material.
Also see how such CDs affect broadcast audio;-
http://www.broadcastpapers.com/radio/OmniaWhatHappens-print.htm
So many options causing so many minute differences - will we ever get the chance to see what Charlotte looks like ?
Cheers ......... Graham.
Have been busy using my limited capabilities to paint up Mum's day room whilst she was in hospital due to a blocked upper bowel. It could be that the codeine based pain killers she was on had actually caused this !!!!
Now she is home again and trying to get over her additional ordeal.
Meanwhile I am trying to catch up on other things I could not get done, and presently, audio is not on the list.
Hi Dragon 2.
Yes the GEM is capable of revealing bad source material and CD player equipment that can be 'grainy' or less accurate on transients. Also as Carlos has hinted, it will even make loudspeakers reproduce differently - as do ALL different NFB loop controlled amplifiers.
See for interest;-
http://www.prorec.com/prorec/articles.nsf/articles/8A133F52D0FD71AB86256C2E005DAF1C
The GEM would probably be best driven by dedicated DACs like the Benchmark or an AQVOX-USB 2 D/A.
Where this is not possible then fractional input hf roll-off filtering could be empirically adjusted to set up a satisfactory reproduction characteristic, and the second version of the JLH class-A already has such input filtering. This can subjectively improve reproduction by 'taking the edge' off *distorted* source material.
Also see how such CDs affect broadcast audio;-
http://www.broadcastpapers.com/radio/OmniaWhatHappens-print.htm
So many options causing so many minute differences - will we ever get the chance to see what Charlotte looks like ?
Cheers ......... Graham.
Hi Graham,
Hope your Mum's OK. Your comments re Codeine bring me to one of my favourite singers - Buffy St Marie who was at Woodstock, etc.. and always put an impassioned argument for the land and the American Indians. She was a Codeine addict at one stage and did a so titled song.
My favourite was "My Country 'tis of thy people you're dying" heavy but real! "Now that the buffalo's gone" is also extremely emotive.
For those that care.
Cheers,
Greg
Hope your Mum's OK. Your comments re Codeine bring me to one of my favourite singers - Buffy St Marie who was at Woodstock, etc.. and always put an impassioned argument for the land and the American Indians. She was a Codeine addict at one stage and did a so titled song.
My favourite was "My Country 'tis of thy people you're dying" heavy but real! "Now that the buffalo's gone" is also extremely emotive.
For those that care.
Cheers,
Greg
Correction
Hi everybody
Thanks Carlos and Graham for the answer.
Just a schematic correction: the current source jfet is N and must be a P.
I often use 2SK30A for current source.
My mistake: i apologize!
Should be J175 Fairchild or Motorola.
Any pnp transistor as current source will do the job too.
Anyway it is about the GEM, not the JLH.
I was asking myself why good and linear transistors like SANKENS and TOSHIBAS sound different in an amp with so much feedback and with no output coil. Motorolas are olds so i can understand!
Regards
Gilles
Hi everybody
Thanks Carlos and Graham for the answer.
Just a schematic correction: the current source jfet is N and must be a P.
I often use 2SK30A for current source.
My mistake: i apologize!
Should be J175 Fairchild or Motorola.
Any pnp transistor as current source will do the job too.
Anyway it is about the GEM, not the JLH.
I was asking myself why good and linear transistors like SANKENS and TOSHIBAS sound different in an amp with so much feedback and with no output coil. Motorolas are olds so i can understand!
Regards
Gilles
Attachments
Hi Gurú, Graham and Dragon...good people together.... yes!
No flags, no limits, no frontiers, Global Government, pride and selfish punished with same on them...published on broadcasting TV... educational punishment have to be social only.... group pressure... criminals banished to some Island..... corruption with shame and some tatoo in the front of the head.
Good Gurú... God bless you!
......................................................................................................
Graham, not so good news about Mum, but, really...i was concerned that things could be even worst.... let's be happy with this new chance, more time to have with her...kiss her and say a fat Charlie (never charlotte!) is praying for her.
.......................................................................................................
Dragondeux.... plaisir monsieur.... pretty schematic, your hand work is pretty, better than my Simulator....ahahaha..those things cannot substitute competence.... i can delay two times more than you to produce the same schematic...your is better!
regards all guys.
Carlos
No flags, no limits, no frontiers, Global Government, pride and selfish punished with same on them...published on broadcasting TV... educational punishment have to be social only.... group pressure... criminals banished to some Island..... corruption with shame and some tatoo in the front of the head.
Good Gurú... God bless you!
......................................................................................................
Graham, not so good news about Mum, but, really...i was concerned that things could be even worst.... let's be happy with this new chance, more time to have with her...kiss her and say a fat Charlie (never charlotte!) is praying for her.
.......................................................................................................
Dragondeux.... plaisir monsieur.... pretty schematic, your hand work is pretty, better than my Simulator....ahahaha..those things cannot substitute competence.... i can delay two times more than you to produce the same schematic...your is better!
regards all guys.
Carlos
Lots of things
Hi,
I have just been catching up with the posts here.
Graham, good to hear that your Mum is now out of hospital. We went through a remarkably similar time with my wife's Mum earlier this year. Thankfully she has recovered so well we can hardly cath here now
Dragon2 -thanks for the great insight into what we can expect from the GEM. I can't wait to hear it here.
I am just waiting for a one of two components to complete the PCB as published here. The heatsinks are now due Wednesday and in the meantime in between family committments I have completed the PCB artwork for the PSU and the Power section of the GEM. Graham - I know you prefer the point to point approach but I thought I'd see how it went on a PCB........ I have decided to move a coupple of components around to improve the grounding and after that I'll publish it if anyone is interested?
It is my intention to show photos of the build units but at the moment our digital camera is not well so I am a bit stuck. As soon as I fix it I'll load up the images onto the forum.
All the best
Hi,
I have just been catching up with the posts here.
Graham, good to hear that your Mum is now out of hospital. We went through a remarkably similar time with my wife's Mum earlier this year. Thankfully she has recovered so well we can hardly cath here now
Dragon2 -thanks for the great insight into what we can expect from the GEM. I can't wait to hear it here.
I am just waiting for a one of two components to complete the PCB as published here. The heatsinks are now due Wednesday and in the meantime in between family committments I have completed the PCB artwork for the PSU and the Power section of the GEM. Graham - I know you prefer the point to point approach but I thought I'd see how it went on a PCB........ I have decided to move a coupple of components around to improve the grounding and after that I'll publish it if anyone is interested?
It is my intention to show photos of the build units but at the moment our digital camera is not well so I am a bit stuck. As soon as I fix it I'll load up the images onto the forum.
All the best
About comparisons etc.
Dragon2 you made a very good work, congratulations. I have made some A to B comparisons between JLH and another amplifier, Mr Molenkamp's DIY amp (schematics is somewhere in this forum) which I use regulalry. I am not able to give a defintite result from this comparison and I want to gather more ears for a final conclusion.
I haven't built GEM yet but I am going to build it soon, i have gathered all the parts, just trying to find time. i will post results when I have something.
About JLH:
I agree with that. It is surely something I can't describe. Sometimes it has less clarity, less punch, less bass than the other amplifier, but it has something that whispers in your ear: "listen to me". I really can't explain it.
Perhaps it is what most people would describe as "more musical" just with other words...
Dragon2 you made a very good work, congratulations. I have made some A to B comparisons between JLH and another amplifier, Mr Molenkamp's DIY amp (schematics is somewhere in this forum) which I use regulalry. I am not able to give a defintite result from this comparison and I want to gather more ears for a final conclusion.
I haven't built GEM yet but I am going to build it soon, i have gathered all the parts, just trying to find time. i will post results when I have something.
About JLH:
I agree with that. It is surely something I can't describe. Sometimes it has less clarity, less punch, less bass than the other amplifier, but it has something that whispers in your ear: "listen to me". I really can't explain it.
Perhaps it is what most people would describe as "more musical" just with other words...
Not only incredible... Graham GEM is now 12 times Guaranteed.
As feedback is arriving Graham personal mail....all them very positive.
This way...now, there are 12 persons having the pleasure to listen to GEM.
GEM is not only an amplifier, alike AKSA, it is a Measurement instrument!...if your speaker did not sound good with GEM.
Give it a good shot and send it to Garbage can!
As GEM 12 times guaranteed... and for a while...just for a while!
ahahaha!
regards,
Carlos
As feedback is arriving Graham personal mail....all them very positive.
This way...now, there are 12 persons having the pleasure to listen to GEM.
GEM is not only an amplifier, alike AKSA, it is a Measurement instrument!...if your speaker did not sound good with GEM.
Give it a good shot and send it to Garbage can!
As GEM 12 times guaranteed... and for a while...just for a while!
ahahaha!
regards,
Carlos
Some photos of the work so far
Hi,
I finally have a digital camera to show a little of the PCBs progress.
I say PCBs because I continued after the original GEM PCB to make a PSU and a small PCB to carry the rest of the components not fiitted to the original PCB.
Here is a photo of the PSU board with dual banks of 4 * 10,000uF caps and fuses fitted. The decoupling caps for the large electrolytics are fitted on the bottom of the board.
More to follow
Hi,
I finally have a digital camera to show a little of the PCBs progress.
I say PCBs because I continued after the original GEM PCB to make a PSU and a small PCB to carry the rest of the components not fiitted to the original PCB.
Here is a photo of the PSU board with dual banks of 4 * 10,000uF caps and fuses fitted. The decoupling caps for the large electrolytics are fitted on the bottom of the board.
More to follow
Attachments
- Status
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