@carageae
I don't have anything to add here except to note that I've never bothered measuring/matching transistors except once or twice at the very beginning, and that was mainly to verify that I had no duds. The circuit will work fine with the natural "as purchased" parameter variation, i.e., with no selection.
If you aren't using my board design, you'll have to take up any build issues with whoever drew that layout.
I don't have anything to add here except to note that I've never bothered measuring/matching transistors except once or twice at the very beginning, and that was mainly to verify that I had no duds. The circuit will work fine with the natural "as purchased" parameter variation, i.e., with no selection.
If you aren't using my board design, you'll have to take up any build issues with whoever drew that layout.
@rjm : Thank you for the reply and for sharing the project of this amplifier. The layout is very similar with yours, AFAIK @Julian RO followed your files, with only minor mods, bigger pads and small design changes. Thank you @Julian RO for sharing this pair of pcb.'s and of course for the Denoiser PCB.
At this moment I listen the amp with FiiO JT1 headphones. In the image below I tested it with some cheap 8 ohms speakers.
It is by far the best detail retrieval amp I built, maybe not my first choice for entertainment listening, but for critical sessions or monitoring this seems to be my near future toy.
In the following days I will do further more tests...now it plays with jumper 1 closed and I chose open loop configuration.
My transistors are BC327/337 with hFE strictly chosen between 438-442 (I bought a lot of them from 3 stores to achieve this pairing). Maybe it couldn't be strictly necessary, but for sure it doesn't hurt. The finals are some NOS C-DIL BD139-140 from electols.com , hFE 174 all.
My power supply is a bit overkill, a symetrical Denoiser supply, followed by the onboard supply, but only as a capacity multiplier, I didn't mount the Zenners. I don't hear any noise with zero input signal.
At this moment I listen the amp with FiiO JT1 headphones. In the image below I tested it with some cheap 8 ohms speakers.
It is by far the best detail retrieval amp I built, maybe not my first choice for entertainment listening, but for critical sessions or monitoring this seems to be my near future toy.
In the following days I will do further more tests...now it plays with jumper 1 closed and I chose open loop configuration.
My transistors are BC327/337 with hFE strictly chosen between 438-442 (I bought a lot of them from 3 stores to achieve this pairing). Maybe it couldn't be strictly necessary, but for sure it doesn't hurt. The finals are some NOS C-DIL BD139-140 from electols.com , hFE 174 all.
My power supply is a bit overkill, a symetrical Denoiser supply, followed by the onboard supply, but only as a capacity multiplier, I didn't mount the Zenners. I don't hear any noise with zero input signal.
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@carageae
You may find it sounds less fatiguing if you switch out that power supply with a simple unregulated unit as originally specified. The boards have enough smoothing that regulated supplies are not needed. I find they tend to deaden the sound - I prefer just transformer + diodes.
You may find it sounds less fatiguing if you switch out that power supply with a simple unregulated unit as originally specified. The boards have enough smoothing that regulated supplies are not needed. I find they tend to deaden the sound - I prefer just transformer + diodes.
Hi all,
I thought I would share some pictures of my Sapphire build with you, this is the second project I've built with pcb's from Richard the first being the Emerald phono stage. As with my Emerald build I'm really pleased and have to say a big thank you to Richard and all the contributors to this thread 😀. On initial power up I had a couple of faults, Richard was able to provide tech support as ever, it's always helpful to ask someone's opinion when fault finding. The fault was simply dry joints on the variable resistor on both boards,..
I've opted for the open loop circuit with selectable gain, with a separate power supply optimised for a pair of Sennheiser HD448, (which I'll upgade in a few months when my wife not looking.... )
I thought I would share some pictures of my Sapphire build with you, this is the second project I've built with pcb's from Richard the first being the Emerald phono stage. As with my Emerald build I'm really pleased and have to say a big thank you to Richard and all the contributors to this thread 😀. On initial power up I had a couple of faults, Richard was able to provide tech support as ever, it's always helpful to ask someone's opinion when fault finding. The fault was simply dry joints on the variable resistor on both boards,..
I've opted for the open loop circuit with selectable gain, with a separate power supply optimised for a pair of Sennheiser HD448, (which I'll upgade in a few months when my wife not looking.... )
Attachments
@gt6hudson. I like the lettering. Did you have it screen-printed? Back then, I had the luxury of operating a laser marking machine at the company, which I also used for some of my front and back panels. Unfortunately, I don't have it anymore for the Sapphire, as I was no longer working there at the time. So how did you get that great lettering?
I used a vynal cutter and bought second hand from Ebay £30 ish, I use it for artwork for guitar fx pedals I build..
I had somehow suspected that it was made with foil, either foil or screen printing. I wouldn't have thought that foil would behave/look so well on aluminum plates. Especially when the aluminum surface is brushed and anodized. Interesting, thanks.
Hi all,
This is a really two questions to everyone on the Sapphire thread, I find listening to my Sapphire that I have a degree of 'cross talk' between channels when listening through a pair of Sennheiser HD448 headphones which I know are a lower price model. I know that this would be partly down to the shared common, ground and also how the headphones are wired. With this being my first steps into hifi headphone amps and headphones.
My questions would be, is a little cross talk to be expected and does it add or detract from the overall sound stage?
My second question is I now need to upgrade from Sennheiser HD448 headphones, what headphones are you all listening to your sapphires with?
This is a really two questions to everyone on the Sapphire thread, I find listening to my Sapphire that I have a degree of 'cross talk' between channels when listening through a pair of Sennheiser HD448 headphones which I know are a lower price model. I know that this would be partly down to the shared common, ground and also how the headphones are wired. With this being my first steps into hifi headphone amps and headphones.
My questions would be, is a little cross talk to be expected and does it add or detract from the overall sound stage?
My second question is I now need to upgrade from Sennheiser HD448 headphones, what headphones are you all listening to your sapphires with?