Hi Nuuk,
I am confused, the PSU is in another box kept about 30 cm away and connected using those XLR type plugs and sockets.
The lay out you discribed is the same as mine apart from except it connects to the buffer board 0v rail. The thing i am wondering i since the Ov rail on the buffer and the PSu input socket are only 2-3 cm away wouldnt it be better to connect everything staright to the 0v rail of the PSu socket?
The other layout i was thinking of was to build a star earth in the top box and then connect that down to the PSU 0v or Buufer 0V rail. This would make the leads on the top all as short as possible to each other and then there would only be one path down to the 0v. Would this be better, i am thinking all those parrallel cable might be a bad idea.
Phil
I am confused, the PSU is in another box kept about 30 cm away and connected using those XLR type plugs and sockets.
The lay out you discribed is the same as mine apart from except it connects to the buffer board 0v rail. The thing i am wondering i since the Ov rail on the buffer and the PSu input socket are only 2-3 cm away wouldnt it be better to connect everything staright to the 0v rail of the PSu socket?
The other layout i was thinking of was to build a star earth in the top box and then connect that down to the PSU 0v or Buufer 0V rail. This would make the leads on the top all as short as possible to each other and then there would only be one path down to the 0v. Would this be better, i am thinking all those parrallel cable might be a bad idea.
Phil
Hi,
I have finally cured my Humm and is was nothing to do with the grounding arrangement. The wall-wart I was using to power the remote board was causing the problem, i simply plugged into a differrent socket away from the rest of the Hifi gear and teh hum stopped completetly. So now i have a superb sounding set up and am very happy with it.
The only slight issue i have is with the sound of bass notes.They are not quite as crisp as i had hoped and i was wondering if there might be something i could be about it. I have used 100uf caps before the second stage of the regulation as opposed to the 10uf that Nuuk recommended and i wondered if that might have an effect, Also i was thinking that i might change the quailty of the final output resistor R4, it is a tiny 1/8watt one and wondered if the rediculousy thin wire on it might effect base notes. The other thing i have read about these buffer is that the Bias resistor R3 can change the tonality of the unit, but i was wondering if i should go up or down? Any thoughts?
Dont get me wrong the unit sounds absolutely gogeous, even my Missus even said it was the best stereo setup she had heard which for someone who be-grudges the time I spend on this hobby really doesn mean something.
Any comments greatful recieved,
Phil
I have finally cured my Humm and is was nothing to do with the grounding arrangement. The wall-wart I was using to power the remote board was causing the problem, i simply plugged into a differrent socket away from the rest of the Hifi gear and teh hum stopped completetly. So now i have a superb sounding set up and am very happy with it.
The only slight issue i have is with the sound of bass notes.They are not quite as crisp as i had hoped and i was wondering if there might be something i could be about it. I have used 100uf caps before the second stage of the regulation as opposed to the 10uf that Nuuk recommended and i wondered if that might have an effect, Also i was thinking that i might change the quailty of the final output resistor R4, it is a tiny 1/8watt one and wondered if the rediculousy thin wire on it might effect base notes. The other thing i have read about these buffer is that the Bias resistor R3 can change the tonality of the unit, but i was wondering if i should go up or down? Any thoughts?
Dont get me wrong the unit sounds absolutely gogeous, even my Missus even said it was the best stereo setup she had heard which for someone who be-grudges the time I spend on this hobby really doesn mean something.
Any comments greatful recieved,
Phil
You could try going either way with R3 Phil - but only one step. For instance try 51R or 75R and see if you can hear any difference.
I can't remembe where but I think that I read that somebody tweaked R1 although I don't remember the value they used.
I doubt that the leadouts of a 1/8 watt resistor will adversely affect the signal.
The only way to find out if 100 uF or 10 uF is better on the second stage of regulation is to to try it!
What speakers do you use?
I can't remembe where but I think that I read that somebody tweaked R1 although I don't remember the value they used.
I doubt that the leadouts of a 1/8 watt resistor will adversely affect the signal.
The only way to find out if 100 uF or 10 uF is better on the second stage of regulation is to to try it!
What speakers do you use?
Hi Nuuk,
Thanks for your continuing advice.
I just ordered some Elna Silmic 10uf of a guy on Pink Fish. I'll try that first i guess. Best have the whole thing at you described before trying to tweak.
My speakers are some reasonable if not amazing kef floor standers. They are Concerto 2's i think, two ways. Nothing huge and they are 89 db sensitive. Not really hard to drive, never had any problems with any of my Nads or my pioneer a400.
Thanks for your continuing advice.
I just ordered some Elna Silmic 10uf of a guy on Pink Fish. I'll try that first i guess. Best have the whole thing at you described before trying to tweak.
My speakers are some reasonable if not amazing kef floor standers. They are Concerto 2's i think, two ways. Nothing huge and they are 89 db sensitive. Not really hard to drive, never had any problems with any of my Nads or my pioneer a400.
Well they are very cheap as well for 'audiophile' caps.
http://www.areyoulocal.com/silmics.asp
Thats is the order page if you want to get some.
Phil
http://www.areyoulocal.com/silmics.asp
Thats is the order page if you want to get some.
Phil
Hi Rabbitz,
Thanks for the reply, any idea which way it would work? Would a lower value of R3 reduce brightness or would that be very system dependant. I guess to start of i might start at the extreme, replace the 120 ohm with what you recommend as a lowest usable value, somewhere around 68ohm. Then i can see if it makes a difference and then tweak up if needed.
I have read that the transistor heat dispation is a limiting factor here, can you get heat sink for these tiny little transistors?
Interesting stuff
Alos i should be mention that i used a 4.7uf film caps as C1 the DC blocking output cap. Should this value effect the tonality of the final delivery?
Phil
Thanks for the reply, any idea which way it would work? Would a lower value of R3 reduce brightness or would that be very system dependant. I guess to start of i might start at the extreme, replace the 120 ohm with what you recommend as a lowest usable value, somewhere around 68ohm. Then i can see if it makes a difference and then tweak up if needed.
I have read that the transistor heat dispation is a limiting factor here, can you get heat sink for these tiny little transistors?
Interesting stuff
Alos i should be mention that i used a 4.7uf film caps as C1 the DC blocking output cap. Should this value effect the tonality of the final delivery?
Phil
Morning Nuuk,
I think i miss typed i meant 68 R as a starting value not 680. The caps in the output is one of those big poplyprolene film caps you can get from Maplin. There are the ones you recommended to me for input coupling caps on my chipamps. I am guessing the quality is fine so if the value isnt that crucial then i dont think the problem lies there.
I think the first stage is to replace the caps then listen for a bit then if needed try reducing the value of R3 and see how it goes.
Thanks for your constant support Nuuk,
Phil
I think i miss typed i meant 68 R as a starting value not 680. The caps in the output is one of those big poplyprolene film caps you can get from Maplin. There are the ones you recommended to me for input coupling caps on my chipamps. I am guessing the quality is fine so if the value isnt that crucial then i dont think the problem lies there.
I think the first stage is to replace the caps then listen for a bit then if needed try reducing the value of R3 and see how it goes.
Thanks for your constant support Nuuk,
Phil
As advised from Andrew, "the 120R resistor sets the bias current. You could go down to maybe 60R for 10mA bias current, or even lower for even more bias current. The limiting factor is the heat dissipation in the transistors". Down to 68R is playing it safe.
Just try the 2 to start with... the standard 120R and then a 68R and if you notice a difference try the in between. I don't think you want to push these little T092's too much.
I only used 2x1uF MKT's in parallel but I'm sure polypropylene would sound better.
Just try the 2 to start with... the standard 120R and then a 68R and if you notice a difference try the in between. I don't think you want to push these little T092's too much.
I only used 2x1uF MKT's in parallel but I'm sure polypropylene would sound better.
Did you buy it off ebay or via the states, trying to work out where to get one from. Also would the pre power supply design work with something like this. I am sure that runnign them both off the same psu wouldnt be a good idea but just out of interest would it work? What size of tranny would you need?
Thinking about building a small setup for use on my pc for gaming. I have a few old amps but something that small would be cool on the desktop. I would also like to try 'class-t' amplification in my main setup to see what it sounds like comapred to my snubberised lm3886. I dont think my speaker are really sensitive enouhg but it sounds like fun.
Phil
Thinking about building a small setup for use on my pc for gaming. I have a few old amps but something that small would be cool on the desktop. I would also like to try 'class-t' amplification in my main setup to see what it sounds like comapred to my snubberised lm3886. I dont think my speaker are really sensitive enouhg but it sounds like fun.
Phil
A friend put me on to this UK source . It was as cheap as buying off Ebay and arrived within two days or ordering!
Yes, if you open up the T-Amp and find where the signal goes in, you can run it from your pre-amp. It uses a (single rail) 12 volt supply. I'm using the plug-in PSU that I use for my digital camera and constructing a regulated 12 volt supply. I'll also try the SMPS!
Oh well,
Got that just too late, been thinking about buying some for a while and just bought a couple of ebay from canada. Not much in the price though only about a quid more! How does it sound stock, i was think about putting two into a small chassis and trying to biamp my speakers. I know you have to be careful with the t-amps since they are already bridged so you cannot use two into a speaker. Need to check if the bi-amp terminals of my kefs are totally seperate or internally joined somehow.
Be very interested to see what you think.
Phil
Got that just too late, been thinking about buying some for a while and just bought a couple of ebay from canada. Not much in the price though only about a quid more! How does it sound stock, i was think about putting two into a small chassis and trying to biamp my speakers. I know you have to be careful with the t-amps since they are already bridged so you cannot use two into a speaker. Need to check if the bi-amp terminals of my kefs are totally seperate or internally joined somehow.
Be very interested to see what you think.
Phil
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