All those transitors on that edge need to be connected to heat sink
Its part of the stability network. Tekko got away with not using it. Play safe and include it.
More questions
I guess C8 and C9 together corresponds to C7 according to the schematic here:
http://www.harrisonaudiolabs.com/Amplifiers/SYMEF/SYMEF.pdf
How important is the values here? (4.7uf) (and what is the purpose?) Could it be reduced or raised?
It is directly in series with the incoming signal and should therefore be of best possible quality?..
This question has been answered. To add
Its a DC blocking capacitor. Yes you could raise it at a cost. polypropylene seems to be the in thing.
Yes you could, go no higher
I think Evette is using the transformer trick, he may be able to advise on a good one.
Hi. I used 1.2mm (16 AWG) Wound around a 12mm (1/2 in) core. I first tried 18 turns as suggested, but I got almost 2 uH on the meter. Then I tried 14 turns and stretched it out to ca 1 in (to fit the two mounting holes that are closest on the PCB). That coil measures close to 1 uH. Note that you have to drill these holes as they are a bit tight. Don't solder some thin wire to the coil to make it fit. This component will carry upwards of 20 Amp! (worst case) Don't skimp on the wire thickness. As long as the length, diameter and number of turns is the same, using 1mm shouldn't have a great effect. Just remember that you will get more resistance and thereby more heat.
When I joined this "project" with SYMEF amplifier, it was mostly of curiosity and a access to get a cheap PCB for a new amplifier + another two PCB for a second built later on (to be determined after a poll among the "test subject").
The construction went smoothly. My experiences and changes in relation to the original, I have described in the # 687 on this thread..
The problem with a distinct hum is resolved. My suspicion went quite early to two old capacitors. My PCB to the stabilized power supply is, as previously told, from a construction built in the mid eighties, that is a nearly 30 years old PCB. After the change of two capacitors (ellyt), SYMEF is completely silent to all kinds of noise.
A lesson to learn about capacitors: Use “fresh”.
My first listening test was performed on my rear speakers that I use for film. This two speakers are SONY flat bass cones. They are also from the eighties. They were found on the garbage dump. The tweeters were destroyed, but has been replaced with very good FOSTEX ribbon tweeters. I have got two very well playing speakers for "almost nothing".
As described in # 687, I received a positive listening experience with SYMEF in the entire tonal range. But it was particularly the tremble that attracted my greatest attention, and I wanted to investigate this further.
On my “main” equipment I play my CDs from a Synology NAS to a Lampizator Transporter (with Squeezebox Duet). The rest: A strongly modified DCX 2496 (Janneman) takes care of the crossover and equalizing. The three final amplifiers are: NAD 208 for two subs and two Goldmund Mimesis clones (3 and 9) for the rest of the range.
You can find some pictures here (post # 1734/35): http://www.diyaudio.com/forums/solid-state/174468-very-best-amplifier-i-have-ever-heard-174.html
Speakers are Magnepan 1.6 and NHT 1259. This equipment, I feel, is of high quality and have so far met my needs and my perception of what constitutes good HiFi.
To get an impression, I did the following: I played a number of discs "in parallel" (on the same time) from 1). My main equipment, and from 2). My Copland 288 connected to SYMEF / SONY. I could switch between these two possibilities (they were synchronized to always be on the same place on the CD), or let them play simultaneously. This way, I could confirm that there really were differences in the reproduction of high frequencies.
The next move was the following: I disconnected the Goldmund 3 from my main equipment. Then I connected SYNEFF, which I have calibrated so that I would not
“ let me fall” for the amplifier that delivers the most powerful output signal to be the "best".
The differences between SYMEF and Goldmund 3 were confirmed. I have been sitting all night and played through countless of my discs:
ONAudio congratulations "We have winner."
I have so far been very pleased with how my main system has played almost every music genres. I say almost, as I have, playing classical music, had a small complaint:
I generally have a large, wide and deep soundstage when I play other kinds of music. I do not experience the same degree been present when I play classical music. My Goldmund 3 has also had a touch of "rawness" in the upper treble that has always annoyed me a bit. Violins and cellos now have more air around them, becomes cleaner.
More clearity in the overall sound. My impression is that the entire orchestra "growing" = being bigger. I am very pleased, also in terms of the fact that I have not used "sophisticated" or expensive components. Rather, we are talking about recycling and what else has been in the "poke box." With a really nice front plate on the old Haffler cabinet, this will be the "finishing touch".
I am now looking forward to receive PCB for the IDIFFQC amplifier. $ 6 will be paid on Pay Pal.
Two new pictures added.
Eivind Stillingen
The construction went smoothly. My experiences and changes in relation to the original, I have described in the # 687 on this thread..
The problem with a distinct hum is resolved. My suspicion went quite early to two old capacitors. My PCB to the stabilized power supply is, as previously told, from a construction built in the mid eighties, that is a nearly 30 years old PCB. After the change of two capacitors (ellyt), SYMEF is completely silent to all kinds of noise.
A lesson to learn about capacitors: Use “fresh”.
My first listening test was performed on my rear speakers that I use for film. This two speakers are SONY flat bass cones. They are also from the eighties. They were found on the garbage dump. The tweeters were destroyed, but has been replaced with very good FOSTEX ribbon tweeters. I have got two very well playing speakers for "almost nothing".
As described in # 687, I received a positive listening experience with SYMEF in the entire tonal range. But it was particularly the tremble that attracted my greatest attention, and I wanted to investigate this further.
On my “main” equipment I play my CDs from a Synology NAS to a Lampizator Transporter (with Squeezebox Duet). The rest: A strongly modified DCX 2496 (Janneman) takes care of the crossover and equalizing. The three final amplifiers are: NAD 208 for two subs and two Goldmund Mimesis clones (3 and 9) for the rest of the range.
You can find some pictures here (post # 1734/35): http://www.diyaudio.com/forums/solid-state/174468-very-best-amplifier-i-have-ever-heard-174.html
Speakers are Magnepan 1.6 and NHT 1259. This equipment, I feel, is of high quality and have so far met my needs and my perception of what constitutes good HiFi.
To get an impression, I did the following: I played a number of discs "in parallel" (on the same time) from 1). My main equipment, and from 2). My Copland 288 connected to SYMEF / SONY. I could switch between these two possibilities (they were synchronized to always be on the same place on the CD), or let them play simultaneously. This way, I could confirm that there really were differences in the reproduction of high frequencies.
The next move was the following: I disconnected the Goldmund 3 from my main equipment. Then I connected SYNEFF, which I have calibrated so that I would not
“ let me fall” for the amplifier that delivers the most powerful output signal to be the "best".
The differences between SYMEF and Goldmund 3 were confirmed. I have been sitting all night and played through countless of my discs:
ONAudio congratulations "We have winner."
I have so far been very pleased with how my main system has played almost every music genres. I say almost, as I have, playing classical music, had a small complaint:
I generally have a large, wide and deep soundstage when I play other kinds of music. I do not experience the same degree been present when I play classical music. My Goldmund 3 has also had a touch of "rawness" in the upper treble that has always annoyed me a bit. Violins and cellos now have more air around them, becomes cleaner.
More clearity in the overall sound. My impression is that the entire orchestra "growing" = being bigger. I am very pleased, also in terms of the fact that I have not used "sophisticated" or expensive components. Rather, we are talking about recycling and what else has been in the "poke box." With a really nice front plate on the old Haffler cabinet, this will be the "finishing touch".
I am now looking forward to receive PCB for the IDIFFQC amplifier. $ 6 will be paid on Pay Pal.
Two new pictures added.
Eivind Stillingen
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Hi Pinnocchio, this is a very broad question
. They are different in terms of topology and some devices. However in terms of listening pleasure, this is the question that is currently under research. PauloPT has listened to both http://www.diyaudio.com/forums/solid-state/199196-new-dawn-1diffqc-amplifier-19.html#post2960014.I hope that this question can be answered soon enough.
Nice read... Soon finished with the 2 modules... Trannie arrived (2*35v - 500VA potted).. That looked nice
4 pcs Elna Cerafine 18000uf caps for psu.. Lots of byv79 or hfa08tb60 diodes for rectification..? - anyone tested them?... They probably sounds more or less identical I guess.
However.. Rs online have messed up my order for heatsinks so they are not here yet..
Will take a picture or 2...
4 pcs Elna Cerafine 18000uf caps for psu.. Lots of byv79 or hfa08tb60 diodes for rectification..? - anyone tested them?... They probably sounds more or less identical I guess.
However.. Rs online have messed up my order for heatsinks so they are not here yet..
Will take a picture or 2...
Common knowledge but it can not be repeated often enough. Some types are less susceptible for aging. Mostly special types that are "ultra long life", "high reliability" etc. For standard and now 10+ years old stuff: don't think, just replace them. The specs of newer industrial types are way better than the old stuff too so you can't go wrong really.
BTW please cut those excess lead wires of the power transistors before they produce a nice short.
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