Build pics
Where I got to after this weekend
Some oddities to the build - I used a thermistor for the loop breaker and a collection of distinctly non boutique parts. I'll be waiting on a few bits for a while I think - silver mica caps aren't available conveniently here
Where I got to after this weekend
Some oddities to the build - I used a thermistor for the loop breaker and a collection of distinctly non boutique parts. I'll be waiting on a few bits for a while I think - silver mica caps aren't available conveniently here
Attachments
Looks good. Did you also link across the BYQ rectifiers? Or maybe you are connecting the output from the SMPS another way. I seem to recall Paul mentioning that we could use ONE of the spades already there if we linked across the diodes. But some thinking is required, lest we short out the SMPS...
Here's a shot of my build. I used one of the spade connectors and bridged across one leg of a diode, as well as the outermost SMD resistor, per Paul's instructions.
Hit a minor snag with the test pins i ordered however, they are too big to fit in the holes. I'll just go with cut-off resistor legs like the bad old days. Not sure about this pic...
Hit a minor snag with the test pins i ordered however, they are too big to fit in the holes. I'll just go with cut-off resistor legs like the bad old days. Not sure about this pic...
Attachments
Last edited:
Inductor check. I compared my inductor to the one reported as correct by Woody in another thread. Looks the same, but i'm not sure. Verification appreciated. Also a shot of the current state of the first channel. Waiting on silver micas and i ordered two less 1N4148 than i needed... :/ How important is the D3, anyone reckon? Maybe i can substitute a led for it, depending on what reverse voltage it may see i guess. Also included in the shot are some of my old school tools...
Attachments
Last edited:
It's alive!
Finished both boards(used SK170 for now as T1), bias and offset setting went like a charm. No time yet to listen, but really happy my FETs seemed to have survived mounting!
I used a fixed 200 ohms(as per Paul's suggestions) resistor in place of T2(to set VAS Ids), will check what current this turns out to give.
Set mine to 37 mV across R18, for 370 mA quiescent. Offset was easily adjusted to 0.00 mV, 3.0 mVAC on speaker terminals with shorted inputs.
For now i'm a very happy camper, and can't wait to give this bad boy a listen!
Finished both boards(used SK170 for now as T1), bias and offset setting went like a charm. No time yet to listen, but really happy my FETs seemed to have survived mounting!
I used a fixed 200 ohms(as per Paul's suggestions) resistor in place of T2(to set VAS Ids), will check what current this turns out to give.
Set mine to 37 mV across R18, for 370 mA quiescent. Offset was easily adjusted to 0.00 mV, 3.0 mVAC on speaker terminals with shorted inputs.
For now i'm a very happy camper, and can't wait to give this bad boy a listen!
Attachments
Last edited:
Ha! That's perceptive of you. I somehow ordered 2 1N4148's too little and decided to use some old LEDs for now. They do blink precariously strong just after powering on, so i will either sub them out for real diodes, or borrow a couple of small BJTs from work and wire them as diodes.
The trick to winding those inductors is to keep the wire quite taut, and aim a couple of millimetres to the right(that is towards the part you've just wound). The trickiest part of the build for me was the mounting of the output FETs, i was very paranoid that i would ruin them from static discharge while finagling them into place.
Another deviation from Hugh's stern recommendation in another thread was my use of 15pf(i believe Greg's preference) as C4 instead of 33pf(Hugh). But i have some 33pf coming so will test it out.
Have not yet fitted C13/C14, have a special idea for those. Oh and i used a 1.2uF / 400V JB JFX as input cap. Fits very nicely and way cheaper than Auricap XO.
Still a little early to say if my choice of C15 & C17 (470uF) and C16 & C18 (1000uf) will work out, since the SMPS300RE so far has only had to deal with one channel powered up at a time. Fingers crossed i will be alright, but i don't expect stellar bass from those small caps. Going to be very interesting how it fares versus my Musical Fidelity B1. Lineup, Greg, Mike, Paul and Hugh vs Tim de Paravicini
The trick to winding those inductors is to keep the wire quite taut, and aim a couple of millimetres to the right(that is towards the part you've just wound). The trickiest part of the build for me was the mounting of the output FETs, i was very paranoid that i would ruin them from static discharge while finagling them into place.
Another deviation from Hugh's stern recommendation in another thread was my use of 15pf(i believe Greg's preference) as C4 instead of 33pf(Hugh). But i have some 33pf coming so will test it out.
Have not yet fitted C13/C14, have a special idea for those. Oh and i used a 1.2uF / 400V JB JFX as input cap. Fits very nicely and way cheaper than Auricap XO.
Still a little early to say if my choice of C15 & C17 (470uF) and C16 & C18 (1000uf) will work out, since the SMPS300RE so far has only had to deal with one channel powered up at a time. Fingers crossed i will be alright, but i don't expect stellar bass from those small caps. Going to be very interesting how it fares versus my Musical Fidelity B1. Lineup, Greg, Mike, Paul and Hugh vs Tim de Paravicini
I saw your post when I happened to wake up at 4am, and that LED was enough to get me out of bed to check I hadn't missed something on my build
Hm! Interesting... I've found myself waiting on caps at the moment for all the spec'd mica parts. After querying Hugh, I resigned myself to waiting for the correct values to arrive from overseas as the local parts were too low a value. Frustratingly that leaves me waiting for a few weeks (and I have correct value ceramics on hand too! Maybe I should just use them for now...)
I went for 100uF for C15 - C18 and I'm curious as to what your special idea for C13/14 is - I just threw a couple of 1uF Polyesters in there (although I'm considering using the extra mount points for another cap underneath)
For the input cap I've ended up using a chinese crossover 1uF MKT, but I had so many choices! All improvised though - a few different x2 caps, a 2uF motor run cap, or even a 10uF polyester... Nothing was he correct size though sadly.
Nice one on the update - it's very inspiring to see others cracking on with it given I spent quite a while yesterday sanding flat the FET mount points on the heatsink
Hm! Interesting... I've found myself waiting on caps at the moment for all the spec'd mica parts. After querying Hugh, I resigned myself to waiting for the correct values to arrive from overseas as the local parts were too low a value. Frustratingly that leaves me waiting for a few weeks (and I have correct value ceramics on hand too! Maybe I should just use them for now...)
I went for 100uF for C15 - C18 and I'm curious as to what your special idea for C13/14 is - I just threw a couple of 1uF Polyesters in there (although I'm considering using the extra mount points for another cap underneath)
For the input cap I've ended up using a chinese crossover 1uF MKT, but I had so many choices! All improvised though - a few different x2 caps, a 2uF motor run cap, or even a 10uF polyester... Nothing was he correct size though sadly.
Nice one on the update - it's very inspiring to see others cracking on with it given I spent quite a while yesterday sanding flat the FET mount points on the heatsink
Last edited:
@Kris - nice matchup, I'll bet a dollar on the allstar DIY team! I reckon the satisfaction of doing it yourself sounds great
@Meanman - I'm actually doing some work on a F5 I made ages ago that was humming as well at the fetzy build. This means I have a nice linear supply sitting on the bench in an open chassis that happens to be the same voltage as the Switchmode psu I'll be using. Maybe I should try a A/B comparison... That said, it seems you've made a few of these so I guess you'd know!
@Meanman - I'm actually doing some work on a F5 I made ages ago that was humming as well at the fetzy build. This means I have a nice linear supply sitting on the bench in an open chassis that happens to be the same voltage as the Switchmode psu I'll be using. Maybe I should try a A/B comparison... That said, it seems you've made a few of these so I guess you'd know!
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.