kevin gilmore Posted December 21, 2014 Author Report Share Posted December 21, 2014 looking very good Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted December 21, 2014 Report Share Posted December 21, 2014 Any mechanical noise with the SSR? I have given up on them in larger (>=300VA) designs completely. They really don't like inductive loads, best I can tell. Quote Link to comment Share on other sites More sharing options...
Kerry Posted December 21, 2014 Report Share Posted December 21, 2014 I used a larger capacity one for my Blue Hawaii and I've used this particular one in a guitar amp I built with no issues. The transformer here is a 100VA and it's the only thing running through the SSR. Power draw for the amp is about 28VA against the HV side of transformer not accounting for loss. Quote Link to comment Share on other sites More sharing options...
Laowei Posted December 22, 2014 Report Share Posted December 22, 2014 I've been running and monitoring the balance and offset of my KGST, and once set it seems to be very stable. It sounds great as is. I am thinking about just not using the DC servo at all. Is there a safety or other issue that I am unaware of if the servo is not used? Quote Link to comment Share on other sites More sharing options...
mypasswordis Posted December 22, 2014 Report Share Posted December 22, 2014 Wow amazing job as always! Looking forward to the finished result. Could you list parts numbers for those connectors? Quote Link to comment Share on other sites More sharing options...
Pars Posted December 22, 2014 Report Share Posted December 22, 2014 Really nice work Kerry! Quote Link to comment Share on other sites More sharing options...
nopants Posted December 22, 2014 Report Share Posted December 22, 2014 I've been using mine without the servo, no issues Quote Link to comment Share on other sites More sharing options...
n_maher Posted December 22, 2014 Report Share Posted December 22, 2014 Excellent work, as usual, Kerry! Quote Link to comment Share on other sites More sharing options...
chinsettawong Posted December 22, 2014 Report Share Posted December 22, 2014 Very beautiful work Kerry! Quote Link to comment Share on other sites More sharing options...
eggil Posted December 22, 2014 Report Share Posted December 22, 2014 How big is it? Or should I say how small? Quote Link to comment Share on other sites More sharing options...
Kerry Posted December 22, 2014 Report Share Posted December 22, 2014 Thanks for the comments The board size is 5.9" wide and 6.25" deep. The heat sinks that mount to the sides of the board are from heatsinkusa. They're the low profile ones and are a half an inch thick. I'm leaving a .05" gap on either side of the board so the width will be exactly 7" with the sinks. Quote Link to comment Share on other sites More sharing options...
Kerry Posted December 22, 2014 Report Share Posted December 22, 2014 Here's what it will look like in the chassis. This is looking at it from the bottom of the amp. Quote Link to comment Share on other sites More sharing options...
UFN Posted December 22, 2014 Report Share Posted December 22, 2014 Very neat! Was going to complain about the onboard IEC-inlet, but it's quite obvious you didn't have other options //UFN Quote Link to comment Share on other sites More sharing options...
JoaMat Posted December 22, 2014 Report Share Posted December 22, 2014 Looks very compact and elegant indeed. Nice work as always. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted December 23, 2014 Author Report Share Posted December 23, 2014 definitely like how the diy stuff seems to be outpacing a lot of the commercial stuff. Quote Link to comment Share on other sites More sharing options...
nopants Posted December 23, 2014 Report Share Posted December 23, 2014 Here's what it will look like in the chassis. This is looking at it from the bottom of the amp. what's the clearance between the 3675 tabs and the sinks? Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted December 23, 2014 Report Share Posted December 23, 2014 (edited) Maybe 2.54mm? Edited December 23, 2014 by luvdunhill Quote Link to comment Share on other sites More sharing options...
Kerry Posted December 23, 2014 Report Share Posted December 23, 2014 (edited) It's .13" or 3.3mm. That should be plenty. Good guess Marc. Edited December 23, 2014 by Kerry Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted December 23, 2014 Author Report Share Posted December 23, 2014 those can be replaced with a couple of different parts all of which are fully isolated Quote Link to comment Share on other sites More sharing options...
nopants Posted December 23, 2014 Report Share Posted December 23, 2014 Kerry doesn't sound too worried, but iirc there are caps you can place over the to220 packages Quote Link to comment Share on other sites More sharing options...
Kerry Posted December 23, 2014 Report Share Posted December 23, 2014 (edited) I have some sc4686's that I was going to use but the hfe were 20 or less. The sc3675's that I used were 63. I wanted it to be higher so I went with the latter. I also have some 2sc3840's (I've used these before) that have a small exposed tab like the sa1486's. Might have been a better choice (pin out is reversed so you'd need to flip them). Nopants - I've seen you post these parts before. What is the part number. I don't mind being extra cautious. Edit: The FJPF2145 seems like a good choice. Edited December 23, 2014 by Kerry Quote Link to comment Share on other sites More sharing options...
spritzer Posted December 23, 2014 Report Share Posted December 23, 2014 The insulation spec of air is about 100V/mill so you are more than covered. Quote Link to comment Share on other sites More sharing options...
nopants Posted December 23, 2014 Report Share Posted December 23, 2014 I have some sc4686's that I was going to use but the hfe were 20 or less. The sc3675's that I used were 63. I wanted it to be higher so I went with the latter. I also have some 2sc3840's (I've used these before) that have a small exposed tab like the sa1486's. Might have been a better choice (pin out is reversed so you'd need to flip them). Nopants - I've seen you post these parts before. What is the part number. I don't mind being extra cautious. Edit: The FJPF2145 seems like a good choice. I don't remember the exact part number from mouser, I only encountered them in my travels in ebay: http://www.ebay.com/itm/ALUTRONIC-Polyester-Cover-for-TO-220-Transistor-MPN-IK551-LOT-of-80-PCS-/141262283260?pt=LH_DefaultDomain_0&hash=item20e3e361fc Quote Link to comment Share on other sites More sharing options...
Kerry Posted December 28, 2014 Report Share Posted December 28, 2014 I've decided I'm going to build a smaller version of Kevin's digital attenuator boards and add an MCU and small OLED display. I already provisioned the 5V on the PSU (instead of my original thought to do 12V). I've got a .333mA transformer and I'm trying to keep it all around 230mA, which I think I can do. I'm also going to add a USB DAC. I'm really liking what AMB is doing with the Zeta1. Since I want balanced output, I can't use the gamma 1.5. The gamma 3 is more than I need for this and much more than I could fit. I'll likely just keep it to USB (no SPDIF). I'm also likely going to use an ASRC (same from the Gamma2). I've already done this in another DAC. I'm also going to build in some isolation for the I2S and I2C (if I decide to go with software mode on the WM8741). I won't be able to cut dual mono not enough space or power. I had a very cool thought that I should also add a built in digital volt meter. Besides being very cool, this could help adjust the bias between the +/- for each channel. I've got a preliminary design and so far it seems to work in LTSpice. It'll have a range of +/-30V, which is more than I need. I'm going to go with a single knob/encoder with a momentary switch for volume control and to run through the menus. 1 Quote Link to comment Share on other sites More sharing options...
spritzer Posted December 28, 2014 Report Share Posted December 28, 2014 Kevin and I have been discussing something similar if we build a few commercial grade T2's. Quote Link to comment Share on other sites More sharing options...
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