Russ,
Could you pls answer a couple of?s I'm about to pull the trigger and order some Rev Cs but have some ?s
1st all questions are in reference to driving 4ohm speakers.
1. Based on Nationals handy dandy spread sheet anything with more tham 28v rails, I assume this is after rectification, requires a 3886T vs TF. Is this right?
2. If this is true do you have kits available with the 3886T?
3. If I use a toroid with 22v secondaries they will rectify to 30v and according to National's spreadsheet that will result in 6.48amps and 83 watts does that sound about right to you?
4. If not will I have to use a transformer with 20v or less secondaries?
Thx
Mike
Could you pls answer a couple of?s I'm about to pull the trigger and order some Rev Cs but have some ?s
1st all questions are in reference to driving 4ohm speakers.
1. Based on Nationals handy dandy spread sheet anything with more tham 28v rails, I assume this is after rectification, requires a 3886T vs TF. Is this right?
2. If this is true do you have kits available with the 3886T?
3. If I use a toroid with 22v secondaries they will rectify to 30v and according to National's spreadsheet that will result in 6.48amps and 83 watts does that sound about right to you?
4. If not will I have to use a transformer with 20v or less secondaries?
Thx
Mike
kestrel200 said:
Hi Mike,
1) Not based on my experience, at least not for sane listening levels. TF package has worked just fine for me with 4ohm loads and 33-35V rails.
2) I think the kits come with TF because they are less risky for the end users, but if you really really want them I will send you a couple Ts. I would recommend just sticking with the TFs.
3) 22V secondaries will not produce addequate voltage for the voltage drop accross the zeners which regulate the LM318 PS. Stick with 24-25V secondaires or 48VCT.
4) That would definitely not be what I would do 24V secondaries are minimum. This is still very well within the datasheet parameters.
With 24V secondaries you can very safely drive 4 ohm loads. No worries. And if you use the 4" barred boss heatsinks you will not have any issues at all with the TF package. Just be sure to use thermal grease.
Cheers!
Russ
Member
Joined 2003
The "handy dandy" spreadsheet from National calculates for the standard application circuit, given in the datasheet. This circuit is nothing like the typical application circuit in the datasheet and therefore the data obtained from the spreadsheet cannot be applied here.kestrel200 said:
The Mauro boards are meant to work from +-35VDC, which requires a 48VCT transformer. This provides a happy medium in output power to work well with any load from 4 to 8 ohms.
[Edit: Sorry Russ, seems you posted as I was typing
]
It might be helpful for newcomers to this long thread, to mention that Mauro Penasa's Rev a/b/c Amps are meticulously designed and tested over a long period, by a master engineer.
You can have confidence in the design, and Russ and Brian"s implementation in their Twisted Pear RevC kits, which is backed up by many builders of the amp.
You can have confidence in the design, and Russ and Brian"s implementation in their Twisted Pear RevC kits, which is backed up by many builders of the amp.
Hi!
Running in the RevC has been mentioned previously as being of benefit.
I burned in my RevC for 40 hours at about 12.5W (10V ac) average music signal via CD on continuous repeat play. I used Mills 50 watt 8 ohm Power resistors from Parts Connection (US$4.95 each) mounted on Mullard heatsinks from a Lindsay Hood class A amp that I never got around to building.
Although the amp sounded good at first listen after the burn-in, there was improvement after another 10 hours of listening. A further 10 hours brought yet more improvement.
I cannot say how much of the improvement was from the RevC amp, as the new coupling caps in my valve preamp and also my cartridge were not fully run in. However I seem to recall that someone mentioned 50/60 hours running-in was needed.
I will burn in my second pair of RevC boards (which should be arriving soon) with the power resistors, for 60 hours.
Audie.
Running in the RevC has been mentioned previously as being of benefit.
I burned in my RevC for 40 hours at about 12.5W (10V ac) average music signal via CD on continuous repeat play. I used Mills 50 watt 8 ohm Power resistors from Parts Connection (US$4.95 each) mounted on Mullard heatsinks from a Lindsay Hood class A amp that I never got around to building.
Although the amp sounded good at first listen after the burn-in, there was improvement after another 10 hours of listening. A further 10 hours brought yet more improvement.
I cannot say how much of the improvement was from the RevC amp, as the new coupling caps in my valve preamp and also my cartridge were not fully run in. However I seem to recall that someone mentioned 50/60 hours running-in was needed.
I will burn in my second pair of RevC boards (which should be arriving soon) with the power resistors, for 60 hours.
Audie.
Attenuator
Hey folks, just finished an attenuator design which work great with the MyRef.
Here is the thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=74224
Hey folks, just finished an attenuator design which work great with the MyRef.
Here is the thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=74224
I will say I am not a big believer in burn in since I generally do not experience this phenomenon, however my MyRef has definatly gotten alot better since it was first built. The nasality in the mid that was there initialy is now gone.
I think it should be renamed the Black Hole - every time stick on a disc I seem to mysterously loose hours of waking time
I think it should be renamed the Black Hole - every time stick on a disc I seem to mysterously loose hours of waking time
Byrd said:I think it should be renamed the Black Hole - every time stick on a disc I seem to mysterously loose hours of waking time
No "mystery" about it... My wife keeps every minute accounted for.... That b#%ch.
Only saving grace is that she actually hears a difference with this one and now understands why I enjoy this hobby.
Rev_C kit and all parts to build ~ $200
Time equivalent to assemble PCB's and construct complete package ~ $500
Having a product that enlightens absolutely anyone who hears it on the hobby we enjoy PRICELESS...
Byrd said:I will say I am not a big believer in burn in since I generally do not experience this phenomenon, however my MyRef has definatly gotten alot better since it was first built. The nasality in the mid that was there initialy is now gone.
I think it should be renamed the Black Hole - every time stick on a disc I seem to mysterously loose hours of waking time
So... do you still prefer your Leach or is the gap between the two beginning to narrow??
Kit change
So, I am almost out of the Wima 1.0uF polyesters I have been shipping as input caps. Seems to be fairly universally disliked part, so I am planning to change it.
My current plan is a Solen 1uF 400V MKP axial cap (FastCap). Kit price would remain the same. Thoughts?
It shouldl fit flat on the board in the stanard position.
So, I am almost out of the Wima 1.0uF polyesters I have been shipping as input caps. Seems to be fairly universally disliked part, so I am planning to change it.
My current plan is a Solen 1uF 400V MKP axial cap (FastCap). Kit price would remain the same. Thoughts?
It shouldl fit flat on the board in the stanard position.
How about 1 ufd Seimens or Epcos
Brian,
A better part than the 1 ufd Wima is the stacked film and foil made by Siemens/Epcos. These are small also.
The middle one is a naked 1 ufd 100v. These are not very expensive. The going price on the lower one, a 2.2 ufd 100volt is 2.00. Inflation.
George
Brian,
A better part than the 1 ufd Wima is the stacked film and foil made by Siemens/Epcos. These are small also.
The middle one is a naked 1 ufd 100v. These are not very expensive. The going price on the lower one, a 2.2 ufd 100volt is 2.00. Inflation.
George
Attachments
![dsc00225[1].jpg](/community/data/attachments/51/51126-aceb19e0334b25b5983d9d0a646e9cf1.jpg)
George -
What's the pin spacing on those? And who carries them?
I have had very good experiences with the Solens, and have a ready supply of them, which was why I was thinking in that direction.
PS: The issue with the Wima is that it's polyester, not that it's Wima. Just though I should point that out. Most prefer Polypropolene in this position.
What's the pin spacing on those? And who carries them?
I have had very good experiences with the Solens, and have a ready supply of them, which was why I was thinking in that direction.
PS: The issue with the Wima is that it's polyester, not that it's Wima. Just though I should point that out. Most prefer Polypropolene in this position.
Surplus
These are local pick ups. I think at least a couple hundred are laying in the bins.
I used to use the roll type caps also. These stacked film and foil seem better than any metalized film cap no matter what the dielectric.
I did not measure pin spacing, it drops right in the middle position of the new monoblock boards.
George
These are local pick ups. I think at least a couple hundred are laying in the bins.
I used to use the roll type caps also. These stacked film and foil seem better than any metalized film cap no matter what the dielectric.
I did not measure pin spacing, it drops right in the middle position of the new monoblock boards.
George
Attachments
![dsc00234[1].jpg](/community/data/attachments/51/51255-e3abf2078ca5df2a40f6e49716729c44.jpg)
Member
Joined 2003
more pictures
People always like to see pictures of the finished product so here it is. The amp has been built to match my Kookaburra preamp shown here, and once again thanks to Tony D for selling me his parts.
It was hard to get a good picture of the front, but it is black anodized brushed aluminum, and the LED is purple. The XF is a Plitron 400VA, and don't ask how long it took to machine the corners of the heatsinks, because you don't want to know. Enjoy!
People always like to see pictures of the finished product so here it is. The amp has been built to match my Kookaburra preamp shown here, and once again thanks to Tony D for selling me his parts.
It was hard to get a good picture of the front, but it is black anodized brushed aluminum, and the LED is purple. The XF is a Plitron 400VA, and don't ask how long it took to machine the corners of the heatsinks, because you don't want to know. Enjoy!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
