EI Core power transformers
Many builders prefer a "good" EI core transformer. They reason is the limited bandwidth. The added inductance and leakage capactitance naturally filters out power line hash and RFI. The toriods let it all through.
This does not say that the 7.00, 5 pound PE transformer is a good example of EI power transformer.
I do not have any large toriods to compare with, either 15 volt or 30, nothing in the middle. I suspect the 7.00 transformer will work just as well in my system. The advantage of the higher VA toriods should be in one box affairs or where higher power is used.
I calculated once that normal peak output in my system is 10 mW. That comes from 88 dB acoustic peaks and 100 dB efficient speakers. Even cranked up to 94 dB peaks (loud) it still only figures to 100 mW.
At these power output levels a 50 VA transformer may work.
George
Many builders prefer a "good" EI core transformer. They reason is the limited bandwidth. The added inductance and leakage capactitance naturally filters out power line hash and RFI. The toriods let it all through.
This does not say that the 7.00, 5 pound PE transformer is a good example of EI power transformer.
I do not have any large toriods to compare with, either 15 volt or 30, nothing in the middle. I suspect the 7.00 transformer will work just as well in my system. The advantage of the higher VA toriods should be in one box affairs or where higher power is used.
I calculated once that normal peak output in my system is 10 mW. That comes from 88 dB acoustic peaks and 100 dB efficient speakers. Even cranked up to 94 dB peaks (loud) it still only figures to 100 mW.
At these power output levels a 50 VA transformer may work.
George
"The added inductance and leakage capactitance naturally filters out power line hash and RFI"
This is something that I have always heard - and it does make sense. However I would like to know if there is anyone here that could articulate the audible difference between an unfiltered PS that had hash on the AC line and one that did not? What did you hear?
This is something that I have always heard - and it does make sense. However I would like to know if there is anyone here that could articulate the audible difference between an unfiltered PS that had hash on the AC line and one that did not? What did you hear?
I post this with a bit of trepidation as there has already been more than enough acrimony on this thread. It would be my suggestion that specifics relating to transformer selections and how they apply to my_Ref implementations are just fine here, but maybe theoretical discussions about transformers in general should go to another thread dedicated to that topic.
safetyman asked:
As low-level signal carriers the input wires are the most vulnerable to AC noise. I twist my input wires together (3-4 turns/inch) before connecting to the RCA's and boards. This provides some cancelation of interference.
One of the nice things about the way these boards are arranged is the shielding provided by the PS caps. So routing you AC wires across that side of the boards will probably be OK, has been for me.
After your amp is running, if you have hum, you can try different locations for your wires (any of your signal, power or output) in an attempt to eliminate it. Wire location hasn't been the cause of hum for me...I usually overlook something in my haste to play with my new toy...,😕
Hope this helps,
Try to route your mains along the perimeter of your case, using as short a route as possible. Consideration should be given to the switch you will use and it's position on the case. Secure the wires as far as possible from your inputs. The other side (likely to be good enough) and/or the opposite corner (better).
As low-level signal carriers the input wires are the most vulnerable to AC noise. I twist my input wires together (3-4 turns/inch) before connecting to the RCA's and boards. This provides some cancelation of interference.
One of the nice things about the way these boards are arranged is the shielding provided by the PS caps. So routing you AC wires across that side of the boards will probably be OK, has been for me.
After your amp is running, if you have hum, you can try different locations for your wires (any of your signal, power or output) in an attempt to eliminate it. Wire location hasn't been the cause of hum for me...I usually overlook something in my haste to play with my new toy...,😕
Hope this helps,
Guys, thanks for all the input. I think for a beginner like me I better stick to the EI transformers, as they seem less confusing to me. 😀 Toroids are not that easy to come by here, at least that's what I have found and I had a 400VAC EI custom wound for lessthan USD40.00. Toroids would cost much more.
I'll take note of all the pointers on laying out the mains cables. Hopefully, I'll be able to put my GC into the enclosure soon.
One other thing, at present my GC is powered by a 10amps EI trans and the trans is much warmer than when I used a 5amps EI. Is this normal?
Thanks again.
I'll take note of all the pointers on laying out the mains cables. Hopefully, I'll be able to put my GC into the enclosure soon.
One other thing, at present my GC is powered by a 10amps EI trans and the trans is much warmer than when I used a 5amps EI. Is this normal?
Thanks again.
Hey Safetyman, thats what I have been doing too, although I went for custom made 500VA, as it still was cheaper than the cheapest toroid I could get.
Only negative to this approach is how high these trannies are physicaly, if you were to buy a case it would drasticly push up the price. Mine stands just shy of 13cm (+-5").
PS strange how expectances of a thread can colour the way one reads it... after all the nonsense that happened I read the question above as what shoudl I do to avoid best practices... thought it was being sarcastic... until Ed saved the day... good thing I didn't answer then.
Only negative to this approach is how high these trannies are physicaly, if you were to buy a case it would drasticly push up the price. Mine stands just shy of 13cm (+-5").
PS strange how expectances of a thread can colour the way one reads it... after all the nonsense that happened I read the question above as what shoudl I do to avoid best practices... thought it was being sarcastic... until Ed saved the day... good thing I didn't answer then.
Byrd said:
I have experimented extensively with every noise reducing measure that I can think of. I have not yet noticed any noise reduction measure that did not have significant positive effect on sound quality.
The sound becomes cleaner. Things that should sound smooth do. So smooth that it can sound honey sweet ( listen to songbirds singing ) but this does not mean smoothing over detail - quite the opposite. Low level details, micro dynamic & ambience become significantly more audible.
The down side may be that all of the low level grunge from your digital source also becomes audible....so might be best to start noise reduction measures here.
I understand that toroids have HIGHER inductance per turn, therefore need less turns which gives less capacitance and higher bandwidth
Visa versa for EI
Don't forget that the switching diodes also generate noise so post bridge filtering is also necessary which if done may mean that transformer choice is somewhat less critical.
cheers
mike
At the risk of appearing to be going off topic again (sorry but even generalities of engineering apply to this amp 🙄) it all depends on the transformer Safetyman. The better the quality (more efficient) the transformer - the less heat you are going to get from it.
Take a look @ this link for some more info
Take a look @ this link for some more info
safetyman said:
No - should be other way round....😕
But who's worried about a little more heat... if it sound better....😉
A transformer manufacturer told me that transformers can safely operate up to 100 deg C....
safetyman,
If your Amp really is a Gainclone, shouldn't you be asking your questions in a Gainclone Forum?
Audie.
If your Amp really is a Gainclone, shouldn't you be asking your questions in a Gainclone Forum?
Audie.
safetyman said:
The problem may be the primary of that trafo.
It was badly calculated for your mains voltage, for instance, it may have 220V primary and your mains voltage is at around 240V. Measure it.
It will run warmer.
In this case the AC voltage on the secondaries will be slightly higher than what it says on the trafo.
Twisted wires (a pear of 'em)
Hey guys, as I'm being helpful, let me try some more.
Select an arm's length of 2 wires which will become your twisted pair. Tie both ends together. Get your electric (maybe cordless) drill handy. Place one end of the wire loop over a peg (a doorknob will do). Insert the other end of your wire loop into the drill chuck and tighten. Tension the wire loop to straighten it. Place your finger (or a dowel if you have tender skin...Mongo have working hands, he not scared) into the loop at the drill end. Now slowly start the drill. As the twist progresses, move your dowel, er..Mongo finger away from the drill. You're into the learning curve now.
The amount of back pressure and tension you use will determine the twists/inch. You may also see a bias develop to one wire or the other. This is because one is stiffer, in spite of your expectation that they're both xx gauge, "they should be the same". Yeh, right. Don't believe it. More of the learning curve.
You can adjust this so both wires lay the same in the twist. Here's how. Roll your finger towards the wire that wants to stay straight. This will impart more of the twisting energy to the wire that needs it. If you don' like the lay of the wires, back up and start over. From this you'll produce enough for several amps.
On to the disclaimer: I forget whether from Rod Elliot or Marchand or here or where ever I came up with this, I wasn't born with it. (My wife reminds me regularly, "You ain't smart") It and all I know was given to me. I can't claim it, so I give it freely. We were created, so be creative.
Enjoy
Hey guys, as I'm being helpful, let me try some more.
Select an arm's length of 2 wires which will become your twisted pair. Tie both ends together. Get your electric (maybe cordless) drill handy. Place one end of the wire loop over a peg (a doorknob will do). Insert the other end of your wire loop into the drill chuck and tighten. Tension the wire loop to straighten it. Place your finger (or a dowel if you have tender skin...Mongo have working hands, he not scared) into the loop at the drill end. Now slowly start the drill. As the twist progresses, move your dowel, er..Mongo finger away from the drill. You're into the learning curve now.
The amount of back pressure and tension you use will determine the twists/inch. You may also see a bias develop to one wire or the other. This is because one is stiffer, in spite of your expectation that they're both xx gauge, "they should be the same". Yeh, right. Don't believe it. More of the learning curve.
You can adjust this so both wires lay the same in the twist. Here's how. Roll your finger towards the wire that wants to stay straight. This will impart more of the twisting energy to the wire that needs it. If you don' like the lay of the wires, back up and start over. From this you'll produce enough for several amps.
On to the disclaimer: I forget whether from Rod Elliot or Marchand or here or where ever I came up with this, I wasn't born with it. (My wife reminds me regularly, "You ain't smart") It and all I know was given to me. I can't claim it, so I give it freely. We were created, so be creative.
Enjoy
If this is a Gainclone Forum, it infers that all Chip Amps are Gainclones, since the My Reference Amp that this Forum is about,is not a Gainclone.
Please clear up the confusion.
Audie.
billabong said:
Audie and the rest who may have felt offended, I apologise. I am new to the forum and it's workings (still trying to master), coupled by the fact that I am virtual 'zero' on electronics, I posted my questions here. Everytime, I use the search function, I either come up with a zero or there'll be a mountain to scale. My apologies again. No intentions to taint this thread or any disrespect to forum rules. Just desperation.
Ed, I have virtuall all my cables twisted, (not the way you suggested though) and I found that it has made the amp darker. I am using some silver cables from RCA input to the board, but b'coz they are so fine, I'll try to find a way to twist it to see if I get a darker background.
BTW, I believe that this is good practice for amp building not just for GCs, right?
Love to get some toroids but have to look at them later. Thanks everybody.
billabong said:
Please, I have apologised and made out the reasons I posted in this thread. Please accept my apologies and bury the issue. I have read this thread from it's first page till now and that's how much Mauro's deign excites me. I ahve found that many of the very knowledgable were posting here and I just hoped for a quick answer to a quick question.
My sincere apologies to billabong and the forum, but please give me time to navigate thru all this. I beg your understanding and move onwards about , 'say' what's the feedback like for those who have completed this amp???
Audie, please stop the pointless argumentativeness . There are better ways to point out if a thread has wandered, rather than being rude.
Oh, and I have built many chip amps, I call them all gainclones, no matter what chip or how many other parts/topology involved. It's easier.
Not that it is too awefully important, but this forum is for "chip amps" which includes "gainclones".
This particular thread is for a particular "chip amp" which is Mauro's "My Reference" which is by no means a gainclone.
I think the confusion was caused by the use of the term "forum" in place of "thread". 😉
This particular thread is for a particular "chip amp" which is Mauro's "My Reference" which is by no means a gainclone.
I think the confusion was caused by the use of the term "forum" in place of "thread". 😉
safetyman,
I probably should apologise to you for even bringing the matter up.
I am new at this also and should live and let live.
Yours was a general question anyway that could be posted in any amp forum.
I think I am a bit sensitive to the fact that Mauro's amp not a gainclone, and think that people should not continue to call it something that it is not, out of respect to Mauro.
Audie.
I probably should apologise to you for even bringing the matter up.
I am new at this also and should live and let live.
Yours was a general question anyway that could be posted in any amp forum.
I think I am a bit sensitive to the fact that Mauro's amp not a gainclone, and think that people should not continue to call it something that it is not, out of respect to Mauro.
Audie.