thanks, jdkJake..
it'd be great if you could compare it to other branded high end amplifiers like gilmore, schiit, wooaudio, or any other amps
Well, sorry, but that will not happen. I am a DIY amp kind of guy. Mostly tube hybrids, no commercial gear.
This is also my lone SS amp at the moment (hence my reason to build it). So, I am afraid I do not have a reference for you.
@qusp: thank you for your concern
@opc: owen, for the BAL-BAL version, can you design the output to use 6 poles balanced jack? (+, -, ground, on each channel)
that way, i can easily turn the balanced output to single ended using converter whenever i want
there is not going to be an output jack at all and i would hope if there was it wouldnt be one that nobody uses. i suggested one that i'm using, but i never expected it to happen and it doesnt matter because a header is fine. just wire ground along with the poles to the output jack to suit yourself like everyone else will be doing. 1 strip of 6, or 2 strips of 3 x 2.54mm headers is fine is it not?
yeah i know your pain, we only really have farnell local as well, although there is a mouser australia site, the warehouses are not here, so international shipping is the only option until the 200 dollar free shipping amount is reached. so myself and a few other aussie members often throw in together for digikey and mouser orders. it really does turn out cheaper except for tiny orders.
i also do not like their shipping policy. its free which is cool, but you pay for it with the prices, the bad thing is that if they have to get stock in from another country they will ship what they have first and then as other parts come in they come. so i have sometimes received 4 separate express shipments in the space of a week, sometimes with a lone strip of parts worth a dollar. the amount of resources, packing materials, fossil fuels they waste doing this is appalling and even if requested they will not do it any other way.
Owen, are you planning on making the SE-SE boards/kits regardless of the number of requests you get? Since I expect I wont be getting a balanced output source any time soon, I was debating putting my Bal-SE Rev1 kit up for sale and just getting a couple of SE-SE kits (or a kit and set of boards) to build when I have time (the first one is still in the build queue, behind a B22 I'm building for someone).
i wasn't really talking about the output jack itself, but the pins. i did mention in my previous post about output pin having +, -, and ground poles in each channel. if the design provide these 6 poles in the output, i will be more than happy. i won't even use the on board jack if they were provided in the kit, it's too troublesome to adjust the custom case with the on board output jack
well, lucky me that i haven't felt that way about farnell. they save me the cost to go to actual shop, not to mention time
but now that you pointed those things out, well, i don't know how to respond to that
FWIW, I think the dc servo design in that National reference design is bad. You would probably have better results with "the wire". See opc's comment here
http://www.diyaudio.com/forums/head...e-headphone-amplifier-pcbs-7.html#post2527868
"...I would really suggest steering clear of the DC servo circuit used on the reference national design. It's a poor implementation, and it actually has significantly higher DC offset at the output than a properly implemented DC coupled circuit."
I would agree at this point. I've bread boarded that circuit and had less DC offset with the servo removed. I've seen others post similar experiences. I also tried to SPICE just that servo portion and never could get it to work well.
Seems that people who have built "the wire" have had very little DC output offset from the various reports in this thread, which I would attribute to high accuracy resistors, good chips, and opc's good layout.
Just my two cents, your mileage may vary.
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Hi Guys,
The past few days have been pretty busy, but I have an 8 hour flight ahead of me so I plan on finishing up all the layout and routing.
I'll post the results later this evening for comments along with an updated list of people's preliminary orders.
On another note, I will likely be offering full kits this time around sine there are no connectors. In other words, I'll be including everything needed to fully populate the boards.
Mr. Slim:
I will definitely be proceeding with all three desings regardless of the numbers of people interested. I'm going to panelize the different amps onto a common board, so I can put say four of one kind, and two of another to help account for the different demand.
I'll also make extras of each type since I'm sure there will be latecomers.
Cheers,
Owen
The past few days have been pretty busy, but I have an 8 hour flight ahead of me so I plan on finishing up all the layout and routing.
I'll post the results later this evening for comments along with an updated list of people's preliminary orders.
On another note, I will likely be offering full kits this time around sine there are no connectors. In other words, I'll be including everything needed to fully populate the boards.
Mr. Slim:
I will definitely be proceeding with all three desings regardless of the numbers of people interested. I'm going to panelize the different amps onto a common board, so I can put say four of one kind, and two of another to help account for the different demand.
I'll also make extras of each type since I'm sure there will be latecomers.
Cheers,
Owen
While soldering my boards I accidentally burned up R8. However looking back at the board and schematic it appears that it can be left empty in an SE build. The negative input is connected to ground so there is no point in having the 10k between them. Right? I'd really like some back up on this so I don't have put in an order to mouser and to worry less about destroying chips.
Otherwise all is looking well and I'll post pictures as soon as I'm done.
Thanks OPC,
Nelson
Otherwise all is looking well and I'll post pictures as soon as I'm done.
Thanks OPC,
Nelson
As long as you are running SE and the negative input is tied to signal ground, you should be fine.
Not sure what I was thinking when I originally wrote this, but let me correct it:
I took another set of measurements, at ~122VAC at the wall, I am getting ~18.8VAC at the secondaries of the transformers before the rectifiers. After the rectifiers and prior to the regulators, I am measuring about ~23.5V, plus/minus respectively.
Sorry for any confusion.
FYI, with no signal into the amp nor any load, I am measuring about 1.7mV of DC offset.
no, i'm not sure that leaving r8 unpopulated is a good idea, without it the impedances will not be balanced and offset may be effected. even if grounded, it should be grounded through an equal impedance to the signal, otherwise feedback will be different to what is intended. did you cook the pad, or just the part?