mhconley said:
I use a variac and volt meters so I can't answer...
However I think Andrew is doing a WONDERFUL job advocating safety through the dim bulb tester. Saving more people to be able to participate in DIY.
Thank you Andrew..
I received the heatsinks today. Thanks, Troy!
I mounted them using the supplied shoulder bushing, insulator and some artic silver and tested each board separately.
Both boards seem to be working. The relays click and the LED lights. I measured these output voltages with the input shorted:
Board 1: 0.1 mVAC / 0.4 mVDC
Board 2: 0.1 mVAC / 0.2 mVDC
In the next couple of days I plan to mount them in the beginnings of my chassis, hook up the "DACT type" pot I picked up on eBay, fire up my trusty SCPH-1001 PS1 CD player and play them through a pair of speakers.
Martin
I mounted them using the supplied shoulder bushing, insulator and some artic silver and tested each board separately.
Both boards seem to be working. The relays click and the LED lights. I measured these output voltages with the input shorted:
Board 1: 0.1 mVAC / 0.4 mVDC
Board 2: 0.1 mVAC / 0.2 mVDC
In the next couple of days I plan to mount them in the beginnings of my chassis, hook up the "DACT type" pot I picked up on eBay, fire up my trusty SCPH-1001 PS1 CD player and play them through a pair of speakers.
Martin
Attachments
Yup - They're Grrrrreat!
Hi All,
I finally finised two channels of MyRefC and tested them. All seemed OK, and not misbehaving on a spare speaker, so I put them into the main system. As Uriah said to me, the Lightspeed has no trouble driving these amps. My AYA DAC sounded brilliant and the bass from the IPL S3TLM Transmission Line speakers was room-shaking on some tracks. Overall, they are a superb amp, and suit my system well. I socketed the relevant caps, but haven't rolled any yet. The heatsinks barely get warm, even after prolonged high volume playing.
I get a bit of hum, but that's not surprising given they're not cased etc. One think I did find on one amp is that the DC Offset was wandering up and down when I measured it. One of my amps has since reduced it's output and I suspect an misbehaving LM318. I'll build my other two channels and have a look at them all on the 'Scope - the op amps are socketed, so it'll be an easy swap with a new part.
Overall, I'm delighted!! 😀 Many thanks to Mauro, Peter and Uriah for all their hard work in making this great amp available to us! 😎
Cheers
Jon
Hi All,
I finally finised two channels of MyRefC and tested them. All seemed OK, and not misbehaving on a spare speaker, so I put them into the main system. As Uriah said to me, the Lightspeed has no trouble driving these amps. My AYA DAC sounded brilliant and the bass from the IPL S3TLM Transmission Line speakers was room-shaking on some tracks. Overall, they are a superb amp, and suit my system well. I socketed the relevant caps, but haven't rolled any yet. The heatsinks barely get warm, even after prolonged high volume playing.
I get a bit of hum, but that's not surprising given they're not cased etc. One think I did find on one amp is that the DC Offset was wandering up and down when I measured it. One of my amps has since reduced it's output and I suspect an misbehaving LM318. I'll build my other two channels and have a look at them all on the 'Scope - the op amps are socketed, so it'll be an easy swap with a new part.
Overall, I'm delighted!! 😀 Many thanks to Mauro, Peter and Uriah for all their hard work in making this great amp available to us! 😎
Cheers
Jon
Jon,
Nice job man! Dont forget you can remove the DC blocking caps if your DC offset is low. I did some more reading on that and found that less than 100mV is fine but that above 50mV starts to effect quality of sound. How much I have no clue.
So where did you get those beautiful toroids?
Really nice toroids.
Uriah
Nice job man! Dont forget you can remove the DC blocking caps if your DC offset is low. I did some more reading on that and found that less than 100mV is fine but that above 50mV starts to effect quality of sound. How much I have no clue.
So where did you get those beautiful toroids?
Really nice toroids.
Uriah
They are super, aren't they??
225VA, encapsulated and best of all, cheaper than Farnell by a long shot!!
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=223-8831
Build quality is superb and they are very, very quiet! 😎
I'll be getting a couple more when funds allow, so each of my 4 channels is truly monobloc!!
Cheers
Jon
225VA, encapsulated and best of all, cheaper than Farnell by a long shot!!
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=223-8831
Build quality is superb and they are very, very quiet! 😎
I'll be getting a couple more when funds allow, so each of my 4 channels is truly monobloc!!
Cheers
Jon
Cant get the encapsulated kind in 120V 🙁 Would have to get double the secondary voltage and double the amperage on primary and secondary for the encapsulated.
Uriah
Uriah
Folks,
What is the acceptable DC offset on these amps? What is the typical offset?
Last I checked, I was getting roughly 4mV on each channel.
How do I tweak them to reduce the offset?
TIA
Prasad
What is the acceptable DC offset on these amps? What is the typical offset?
Last I checked, I was getting roughly 4mV on each channel.
How do I tweak them to reduce the offset?
TIA
Prasad
DC Offset
Speaking of which, I measured my amps at the output, but with the input unshorted (or connected to source). I recall shorting input to ground being mentioned. A Google search wasn't that helpful as I found advice exactly as I did. 😕
Clarification gratefully sought, please!!
Cheers
Jon
Speaking of which, I measured my amps at the output, but with the input unshorted (or connected to source). I recall shorting input to ground being mentioned. A Google search wasn't that helpful as I found advice exactly as I did. 😕
Clarification gratefully sought, please!!
Cheers
Jon
Re: DC Offset
Now disconnect the short and connect the source.
Check the offset again.
It should be the same but sometimes it changes. Do check for each source if you have a number of pre-amps or intend to direct drive from music sources.
check the output offset of the amplifier alone. To do this you should short the input hot (Signal flow/line) to the input cold(signal return).jonclancy said:
Now disconnect the short and connect the source.
Check the offset again.
It should be the same but sometimes it changes. Do check for each source if you have a number of pre-amps or intend to direct drive from music sources.
Thanks!!!
Thanks everyone - that's all perfectly clear now!! 😀
BTW, the Grounding / Safety Earth thread has changed my attitude towards mains-powered projects entirely. It should be made compulsory reading on joining the forum!
😎
http://www.diyaudio.com/forums/showthread.php?s=&threadid=115698
Cheers
Jon
Thanks everyone - that's all perfectly clear now!! 😀
BTW, the Grounding / Safety Earth thread has changed my attitude towards mains-powered projects entirely. It should be made compulsory reading on joining the forum!
😎 http://www.diyaudio.com/forums/showthread.php?s=&threadid=115698
Cheers
Jon
Just a head up...
Finally I fixed my bad channel. Replacing the LM3886 stopped that noise.
Thanks guys for your help. Now I can work on the enclosure. 😀
Finally I fixed my bad channel. Replacing the LM3886 stopped that noise.
Thanks guys for your help. Now I can work on the enclosure. 😀
Another fine pair.....
... or MyRefC amps!! Same toroids, though! 😉
I finished these this morning and they tested absolutely fine. DC offset is 0.9mV - must be bouncing off the accuracy limits of my DMM to be honest.
Hooked up to the big speakers, I get the same HUGE soundstage and MASSIVE bass. These amps are only half the power of my Arcams, but seem to have a synergy with my system.
This pair were built completely stock - no sockets (apart from the LM318) or substitutions. As I have the other pair socketed, it'll make rolling easy. Sounds so good, I don't know if I can be bothered!! 😉 I might bung them on the scope and see if there's anything to see (dual window) between them, and I still have one of the first pair to have a look at (decided to reduce power output on its own).
My plan is to install the trafos (all 4) in a separate case with umbilicals to the amp box. Safety earth will be fed back to the power box. Signal ground will be starred and linked to safety earth with a Safety Loop Breaker circuit. As far as I see it, there is no power common (4 boards, 4 trafos).
Comment and suggestions gratefully recieved!
All in all, a great deal learned, fun had, and at Bank/Mrs-friendly cost!
Thanks again, guys! 😎
Jon
... or MyRefC amps!! Same toroids, though! 😉
I finished these this morning and they tested absolutely fine. DC offset is 0.9mV - must be bouncing off the accuracy limits of my DMM to be honest.
Hooked up to the big speakers, I get the same HUGE soundstage and MASSIVE bass. These amps are only half the power of my Arcams, but seem to have a synergy with my system.
This pair were built completely stock - no sockets (apart from the LM318) or substitutions. As I have the other pair socketed, it'll make rolling easy. Sounds so good, I don't know if I can be bothered!! 😉 I might bung them on the scope and see if there's anything to see (dual window) between them, and I still have one of the first pair to have a look at (decided to reduce power output on its own).
My plan is to install the trafos (all 4) in a separate case with umbilicals to the amp box. Safety earth will be fed back to the power box. Signal ground will be starred and linked to safety earth with a Safety Loop Breaker circuit. As far as I see it, there is no power common (4 boards, 4 trafos).
Comment and suggestions gratefully recieved!
All in all, a great deal learned, fun had, and at Bank/Mrs-friendly cost!
Thanks again, guys! 😎
Jon
Nice Job Jon!! So glad you are thrilled with their performance.
I do guarantee increase in sound quality with the removal of the input caps. I also guarantee increase in sound quality with the Lightspeed. So you have minimum two things to look forward to.
Now with regard to opamp rolling... I would read the original thread. It was very frowned upon for the most part. The opamp has a great slew rate and THATs what makes it the opamp for this circuit, not whether or not its a BurrBrown or LM4562 or other hot shot opamp 🙂 So I just suggest searching the original thread first.
Have fun!
Uriah
I do guarantee increase in sound quality with the removal of the input caps. I also guarantee increase in sound quality with the Lightspeed. So you have minimum two things to look forward to.
Now with regard to opamp rolling... I would read the original thread. It was very frowned upon for the most part. The opamp has a great slew rate and THATs what makes it the opamp for this circuit, not whether or not its a BurrBrown or LM4562 or other hot shot opamp 🙂 So I just suggest searching the original thread first.
Have fun!
Uriah
Jon,
Glad to see you're up and running with 3 out of 4.
Rolling opamp is not advised. There is nothing to be gained and possibly something to be lost, according to the designer and experimenters in the original thread. Mauro was no dummy, and he used the BEST sounding opamp for this circuit. These are amazing little amplifiers.
Putting trafos in a separate box probably won't provide any improvements, either. The amps should be dead silent, even with a transformer only inches away. If not, there is something else wrong. Unless you're doing it for practical reasons such as space or enclosure availability, long umbilicals may very well contribute more problems.
The single most critical area to be improved sonically is the input cap. It's really that simple. If you want to experiment and make your amps sound better, spend as much time and money as you can on optimizing that single component with polypro or teflon caps, either high quality metalized film, or actual film and foil. They do not need to be mounted on the actual PCB. Or as Uriah suggests, eliminate them, but understand the risk.
Peace,
Tom E
Glad to see you're up and running with 3 out of 4.
Rolling opamp is not advised. There is nothing to be gained and possibly something to be lost, according to the designer and experimenters in the original thread. Mauro was no dummy, and he used the BEST sounding opamp for this circuit. These are amazing little amplifiers.
Putting trafos in a separate box probably won't provide any improvements, either. The amps should be dead silent, even with a transformer only inches away. If not, there is something else wrong. Unless you're doing it for practical reasons such as space or enclosure availability, long umbilicals may very well contribute more problems.
The single most critical area to be improved sonically is the input cap. It's really that simple. If you want to experiment and make your amps sound better, spend as much time and money as you can on optimizing that single component with polypro or teflon caps, either high quality metalized film, or actual film and foil. They do not need to be mounted on the actual PCB. Or as Uriah suggests, eliminate them, but understand the risk.
Peace,
Tom E
Re: Another fine pair.....
I can assure you, Jon, that it could sound even better 😉
C13, C9 and C21 have the biggest impact but also others components swap are clearly audible.
In Rev A LM318 can be swapped with others opamps but in Rev C it is not advised because one of the mods is related to the compensation network of the LM318...
jonclancy said:This pair were built completely stock - no sockets (apart from the LM318) or substitutions. As I have the other pair socketed, it'll make rolling easy. Sounds so good, I don't know if I can be bothered!! 😉
...
Comment and suggestions gratefully recieved!
I can assure you, Jon, that it could sound even better 😉
C13, C9 and C21 have the biggest impact but also others components swap are clearly audible.
In Rev A LM318 can be swapped with others opamps but in Rev C it is not advised because one of the mods is related to the compensation network of the LM318...