[bdinnerv]

I finally pulled my finger out, ordered the last couple of bits I needed to do this project and got stuck into it last night. All complete!

It seems to power up without letting out any magic smoke and the led's turn on. I dont have a cable at present to connect to the input (have one turning up tomorrow) so cannot test audio at the moment. Hooking up headphones and cranking the volume up does reveal a little bit of noise which I think is a good thing. Not sure what other steps / measurements I can take to verify all is OK.

The smaller SMD parts were a bit tricky, especially after a coffee in the morning which did not help but managed to get it all done in a couple of hours. I have parts to complete a second one (minus 2 resistors that I put in in the incorrect position and damaged when removing so had to raid the second parts set) so may have a go at a second one sometime soon but at the moment just looking forward to testing this one out.

Cheers,

Ben

 

[Paladin79]

I finally pulled my finger out, ordered the last couple of bits I needed to do this project and got stuck into it last night. All complete!

It seems to power up without letting out any magic smoke and the led's turn on. I dont have a cable at present to connect to the input (have one turning up tomorrow) so cannot test audio at the moment. Hooking up headphones and cranking the volume up does reveal a little bit of noise which I think is a good thing. Not sure what other steps / measurements I can take to verify all is OK.

The smaller SMD parts were a bit tricky, especially after a coffee in the morning which did not help but managed to get it all done in a couple of hours. I have parts to complete a second one (minus 2 resistors that I put in in the incorrect position and damaged when removing so had to raid the second parts set) so may have a go at a second one sometime soon but at the moment just looking forward to testing this one out.



Cheers,

Ben

It looks to be very nice work!

 

[bdinnerv]

Just fired it up for the first time with a pair of Audeze iSine-20's - input is coming from the pre-out of a Schiit Fulla at the moment so not the most direct route but have to say, I am pretty happy with this little thing! There was some distortion to start with but then realized I have the volume on the Fulla too low for pre-outs, bumped it up to the prescribed 3am and the coaster sounds great.

I have not checked the tubes yet but there is no noticeable level difference from L->R so may just leave it. Will have to give it a go with the LCD-GX's and see how they go on it but with the iSine 20's, am only running it at about 7:15pm on the volume pot.

Am pretty chuffed with this!

 

[Paladin79]

Just fired it up for the first time with a pair of Audeze iSine-20's - input is coming from the pre-out of a Schiit Fulla at the moment so not the most direct route but have to say, I am pretty happy with this little thing! There was some distortion to start with but then realized I have the volume on the Fulla too low for pre-outs, bumped it up to the prescribed 3am and the coaster sounds great.

I have not checked the tubes yet but there is no noticeable level difference from L->R so may just leave it. Will have to give it a go with the LCD-GX's and see how they go on it but with the iSine 20's, am only running it at about 7:15pm on the volume pot.

Am pretty chuffed with this!

I set up a separate coaster amp with sockets so I could plug in various tubes and match them but then I built a lot of those amps and helped friends with their tubes. There are a couple ways to do it but I ran identical square wave signals to each channel then monitored the outputs on a dual trace oscilloscope. It was quick and easy and left little doubt.

I have since moved on to my own design on a tube amp but it was fun to mess around with kits and try to figure out what kind of cabinet might work with a round circuit board. This is one of my current projects under test, before I began adding control pots and jacks.

 

[bdinnerv]

I set up a separate coaster amp with sockets so I could plug in various tubes and match them but then I built a lot of those amps and helped friends with their tubes. There are a couple ways to do it but I ran identical square wave signals to each channel then monitored the outputs on a dual trace oscilloscope. It was quick and easy and left little doubt.

I saw your original post re sockets and thought about doing it but then figured I dont have the test equipment so what is the point. I have 8 or so spare boards and another amp project under way (this time SS) so may have to invest in some basics. In this instance, it seems I just got lucky.

 

[Paladin79]

I saw your original post re sockets and thought about doing it but then figured I dont have the test equipment so what is the point. I have 8 or so spare boards and another amp project under way (this time SS) so may have to invest in some basics. In this instance, it seems I just got lucky.

To be honest, many I tested were very close matches to each other when dealing with new tubes so you are probably fine as the amp sits.

I did a few solid state kits and have owned a lot of it through the years but at this stage in my life, I only do Class A tube amps but that is a personal preference.

 

[sam6550a]

To be honest, many I tested were very close matches to each other when dealing with new tubes so you are probably fine as the amp sits.

I did a few solid state kits and have owned a lot of it through the years but at this stage in my life, I only do Class A tube amps but that is a personal preference.

Correction please---Class A tube amplifiers with world class woodwork packaging.

 

[bdinnerv]

I did a few solid state kits and have owned a lot of it through the years but at this stage in my life, I only do Class A tube amps but that is a personal preference.

I have a pair of LCD-4's that are on the warmish side coupled with a Yggy + MJ2 at present and want to hear what the LCD4's will sound like with a non-tube amp / more "true" / no tube coloration amplification (Still with the Yggy) so am building a Kevin Gilmour CFA3 + GRLV + digital stepped attenuator as a dual mono balanced setup - bit of a step up from the Coaster but should be easier in a lot regards due to through-hole vs SMD. I may look at a larger tube project after this.

 

[Paladin79]

Correction please---Class A tube amplifiers with world class woodwork packaging.

Check out this rainbow poplar I cut yesterday, it is now one of my favorites.

 

[tod-hackett]

Would it be possible for one to stare at pictures like this and solder together a working amplifier? Other than a soldering iron, what else would one need?

 

[damaged ears]

Here is my coaster build, for the smb parts I used solder paste and a toaster oven. Sounds great. Thanks to Jason for the pcb. The pads are huge making placing parts much easier and the space between the pads helps avoid solder bridges.

 

[JamminVMI]

Here is my coaster build, for the smb parts I used solder paste and a toaster oven. Sounds great. Thanks to Jason for the pcb. The pads are huge making placing parts much easier and the space between the pads helps avoid solder bridges.

Looks brilliant!

 

[damaged ears]

Would it be possible for one to stare at pictures like this and solder together a working amplifier? Other than a soldering iron, what else would one need?

Well you can get the Bill of Material from the Schiit website along with the schematic. Assuming you have a history of soldering through hole devices, but no smb experience, you could, for very few dollars, buy a smb solder practice board off Amazon. With less than an hour practice you should be ready to solder. But this project does require some skills beyond soldering. Due to the chip shortage you will need to find alternatives for some of the parts called out by Jason in the BoM. There are also some errors with regards to part count in the BoM so you need to be careful of that as well. One of the parts is obsolete and the only one holding stock of that part is in China and shipping to the US is very expensive from that company. The good thing is that the substitute part suggested by Mouser is pretty much a drop in replacement. I bought the parts a couple of months ago and then sat on it while I finished other projects. One night I decided to learn how to solder smb parts. Because I already had an appropriate hot air gun I decided to learn how to solder with that. After the first one I decided to try the toaster oven. That required more careful placement of solder paste and stuffing the whole board at once.

The good news is that, as I stated above, the pads are huge, the parts are big, the spacing between pads helps avoid bridging and the traces are easy to see, so figuring out diode orientation is pretty straight forward. I would suggest that you get a magnifying desk light to help. And good quality tweezers, toothpicks help also with the small moments of parts on the board.

 

[Paladin79]

Would it be possible for one to stare at pictures like this and solder together a working amplifier? Other than a soldering iron, what else would one need?

I got the first Coaster amps going (other than those done at Schiit) and soldered all parts with a standard soldering iron so it can be done. I still have a full parts cabinet if any of you cannot locate parts.

 

[damaged ears]

I got the first Coaster amps going (other than those done at Schiit) and soldered all parts with a standard soldering iron so it can be done. I still have a full parts cabinet if any of you cannot locate parts.

The part that is obsolete is Q102,202 Toshiba-2SA1312BLTE85LF, the suggested remplacement part is: 2SA1163-BLLF and it seems to work fine in the coaster.