BrianDonegan said:
Brian, thanks for the clarification. After reading Nordic's post, I went out and ordered a 22-0-22 400VA trafo.
I'll try it out on the amp when I build it and see if there's anything beneficial.BTW, how do you rate the My ref kit (as put up on Twisted Audio's website) against something like the Aleph3 or 30. If you don't want to post it here plese mail me as I am most interested in opinions. That goes for anyone who has built and auditioned this amp and willing to share that bit of info. I'll be most grateful to hear from you guys.
Thanks.
The transformer rating of 8A means that you can run it continuesly at 8A average output without it getting too hot.
It does not mean that you cannot get a 10A or 11A peak.
At either 8 or 10 amps the voltage will drop compared to 1A output but good sized reseviour caps and feed back will minimise the effect of this.
so, no worries about getting max power from chip...
mike
It does not mean that you cannot get a 10A or 11A peak.
At either 8 or 10 amps the voltage will drop compared to 1A output but good sized reseviour caps and feed back will minimise the effect of this.
so, no worries about getting max power from chip...
mike
One of those cases where everyone is right. Peak current is 11A, but that will be a rare achievement while listening to music, and the 20kuF will take care of thoe musical peak current.
That's a nice bridge. Let us know if you can hear a difference. I am open to changing it, but would need to be sure not to upset the kit cost.
That's a nice bridge. Let us know if you can hear a difference. I am open to changing it, but would need to be sure not to upset the kit cost.
Well I was mainly right that you don't need a huge trafo to listen to this amp at low volume levels and you guys were right that it is an excellent amp.
Let me explain.
When I switched the 120va 18v trafo for two 220va 12v trafos with the secondaries in series (24V) I saw a few improvements but not very big.First of all it could go louder without strain.This is to be expected.At lower volumes things were not that different.A little bit clearer in the bass and slightly wider soundstage BUT the annoying quality in the upper midrange was still there.Again a lack of air and some graininess that did not feel natural.
It was not until I started playing with the biasing of the zeners that I got the sound I was more or less expecting.When I went from the 1k resistors to about 680 ohm there was a dramatic IMHO change in the sound.Suddenly there was more space depth and air and smoother high freq extension.
I finally settled on 600 ohms which I found gave an even better presentation in the mids and highs.
I cannot for the life of me understand why this should affect the sound as much as it does.After all we are not talking about biasing a signal carrying device.But all I can say is that it does in a big way.
Now this amp sounds really really good.Very hard to choose between it and the Aleph X (which in my book sounds much better than the normal Aleph I had before ).I need to listen a bit more and split some hairs.
I also find that in my set up it does not need an active pre like some other amps.It has plenty of gain and does not really lose dynamics with a passive pre.The active pre takes away some transparency.
Now tomorrow if everything works out I may take it to Audiopax a couple of blocks away and plug into their reference system and see how it fares .
Heh, heh ...would anybody here like to know the results?
Let me explain.
When I switched the 120va 18v trafo for two 220va 12v trafos with the secondaries in series (24V) I saw a few improvements but not very big.First of all it could go louder without strain.This is to be expected.At lower volumes things were not that different.A little bit clearer in the bass and slightly wider soundstage BUT the annoying quality in the upper midrange was still there.Again a lack of air and some graininess that did not feel natural.
It was not until I started playing with the biasing of the zeners that I got the sound I was more or less expecting.When I went from the 1k resistors to about 680 ohm there was a dramatic IMHO change in the sound.Suddenly there was more space depth and air and smoother high freq extension.
I finally settled on 600 ohms which I found gave an even better presentation in the mids and highs.
I cannot for the life of me understand why this should affect the sound as much as it does.After all we are not talking about biasing a signal carrying device.But all I can say is that it does in a big way.
Now this amp sounds really really good.Very hard to choose between it and the Aleph X (which in my book sounds much better than the normal Aleph I had before ).I need to listen a bit more and split some hairs.
I also find that in my set up it does not need an active pre like some other amps.It has plenty of gain and does not really lose dynamics with a passive pre.The active pre takes away some transparency.
Now tomorrow if everything works out I may take it to Audiopax a couple of blocks away and plug into their reference system and see how it fares .
Heh, heh ...would anybody here like to know the results?
Ok - as promised. The amp is now assembled sans chassis. This only took a day, so quick assembly - and no problems encountered. Pics are available on my project pics gallery.
Initial impressions from my side are that it sounds good, but I still prefer my new version Leach Amp that I have also recently built. There seems to be more texture to the mids. That "annoying quality in the upper midrange" rings true for me so I will try the resistor value change suggested - well maybe...
The female camp however prefers the MyRef to the Leach. It was described as smoother and clearer or more intelligable with more tunefull bass.
Either way - I am happy with the overall sound, it is certainly better than alot of commercial amps I have heard and would have no problem recommending the amp to others - especially less experienced builders. It does not run hot which is a big plus - especially if you are looking at multichannel.
Thanks Mauro, Russ & Brian for bringing this creation to the community.
Initial impressions from my side are that it sounds good, but I still prefer my new version Leach Amp that I have also recently built. There seems to be more texture to the mids. That "annoying quality in the upper midrange" rings true for me so I will try the resistor value change suggested - well maybe...
The female camp however prefers the MyRef to the Leach. It was described as smoother and clearer or more intelligable with more tunefull bass.
Either way - I am happy with the overall sound, it is certainly better than alot of commercial amps I have heard and would have no problem recommending the amp to others - especially less experienced builders. It does not run hot which is a big plus - especially if you are looking at multichannel.
Thanks Mauro, Russ & Brian for bringing this creation to the community.
Ross, it is looking good.
where did you get the heatsinks. very nice. i see you are also running with a lower voltage. it is much better with 35/36 volt. and you will have to give it alot of time to burn in. all four of mine took upto 50 hrs and more to sound OK. you will see in my early mails , that i was annoyed with the sound of the upper mids and highs. well time cured that and it relaxed alot
where did you get the heatsinks. very nice. i see you are also running with a lower voltage. it is much better with 35/36 volt. and you will have to give it alot of time to burn in. all four of mine took upto 50 hrs and more to sound OK. you will see in my early mails , that i was annoyed with the sound of the upper mids and highs. well time cured that and it relaxed alot
Hey Rudi - Thx.
The heatsinks can be gotten from Mantech still i think - although I did get those years ago.
The transformer label is a bit misleading. it is 22V @ 220V Input. The amp is actually running 35V loaded DC Rails. It is also not a 6A Transformer, but more like 10 / 12 A as I am sure you can tell by the size.
I will run this boy in before making any changes. Better get my power resistors out.
The heatsinks can be gotten from Mantech still i think - although I did get those years ago.
The transformer label is a bit misleading. it is 22V @ 220V Input. The amp is actually running 35V loaded DC Rails. It is also not a 6A Transformer, but more like 10 / 12 A as I am sure you can tell by the size.
I will run this boy in before making any changes. Better get my power resistors out
.
I think next time us SA guys should communicate before ordering, think we could save a bit on shipping by doing one order.
At the moment I'm quite interested in Franz's mini valve buffered GC too but it will have to wait till next month I guess... not nice being poor hey.
Rudi did you get the picture of the transistor sockets?
At the moment I'm quite interested in Franz's mini valve buffered GC too but it will have to wait till next month I guess... not nice being poor hey.
Rudi did you get the picture of the transistor sockets?
Listen guys just a special thanks to Rudi, who not only organised the components for me but shipped it overnight, even before letting me know how much it costs, and man was it cheap compared to what I have been looking at.
Living on a dissablity pension I don't always have the buying power to organise good deals, people like this are like angels who make what would otherwise be a hard road, an easy highway.
Living on a dissablity pension I don't always have the buying power to organise good deals, people like this are like angels who make what would otherwise be a hard road, an easy highway.
I see in the last dozen posts that Russ and Brians great kit is motivating less experienced DIYers like myself into this facinating hobby. Sincerest thanks to you guys, and of course Mario for making this happen.
I have received the kit and was blown away by how well laid out, organized, and well labeled everything was. It obviously took a lot of thought and effort.
The upside of all this is that there will be more recruits for future projects, the down side is that there will be more ignorant questions like the two I have below. Please be kind.
First: On fusing. I assume a fuse on the mains AC input is required (in my case 120 volt). What value fuse should I use. In addition to this what other fusing is recommended and of what values. Bear in mind I am a new kit builder and I would rather have too many fuses to avoid early damage and then remove them for audio quality later if it does not smoke.
Second: The chassis I am using is set up for a 3 pronged plug with the ground screwed to the chassis. Should I connect this ground to the chassis or not. If I do does it matter which of the polarized AC plugs I connect to which transformer lead? Thanks in advance for your help.
George
I have received the kit and was blown away by how well laid out, organized, and well labeled everything was. It obviously took a lot of thought and effort.
The upside of all this is that there will be more recruits for future projects, the down side is that there will be more ignorant questions like the two I have below. Please be kind.
First: On fusing. I assume a fuse on the mains AC input is required (in my case 120 volt). What value fuse should I use. In addition to this what other fusing is recommended and of what values. Bear in mind I am a new kit builder and I would rather have too many fuses to avoid early damage and then remove them for audio quality later if it does not smoke.
Second: The chassis I am using is set up for a 3 pronged plug with the ground screwed to the chassis. Should I connect this ground to the chassis or not. If I do does it matter which of the polarized AC plugs I connect to which transformer lead? Thanks in advance for your help.
George
Hi George-
Glad you like the kit. I hope yoy are right about making it easier for newbies to get into the hobbie, that is one of our goals.
For the fuse, I would put a 5A or so on the AC line coming into the amp, ahead of the transformer, as close to the entry as possible. Additional fuses are not really needed. Fuses are, generally speaking, slow to blow compared to transistors, so they won't offer too much protection for them. Some other generous soul might suggest a good size for fuses between the trafo and board (I am not sure).
For the ground, I would tie it to the chassis, but then not connect the gnd on the amp boards to the chassis ground, and be sure the RCA (input) and speakers jacks are isolated from the chassis. This will give you the protection of ground if the chassis somehow becomes live. Attaching the grounded chassis to the amp circuit can create a bunch of noise problems.
For the trafo wiring, it doesn't matter which AC line goes to which trafo primary.
Hope this helps. These are not dumb questions. They would be dumb if you were asking just after electrocuting yourself.
Glad you like the kit. I hope yoy are right about making it easier for newbies to get into the hobbie, that is one of our goals.
For the fuse, I would put a 5A or so on the AC line coming into the amp, ahead of the transformer, as close to the entry as possible. Additional fuses are not really needed. Fuses are, generally speaking, slow to blow compared to transistors, so they won't offer too much protection for them. Some other generous soul might suggest a good size for fuses between the trafo and board (I am not sure).
For the ground, I would tie it to the chassis, but then not connect the gnd on the amp boards to the chassis ground, and be sure the RCA (input) and speakers jacks are isolated from the chassis. This will give you the protection of ground if the chassis somehow becomes live. Attaching the grounded chassis to the amp circuit can create a bunch of noise problems.
For the trafo wiring, it doesn't matter which AC line goes to which trafo primary.
Hope this helps. These are not dumb questions. They would be dumb if you were asking just after electrocuting yourself.