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Courtiestown - Naim Amplifier (Avondale) Upgrade Project

I'm with Laverda 're inductors stopped using them long time ago, I use a 100VA c/core custom transformer into some 6A Qspeed diodes followed by a pair of 6800uF 100V caps into the VBE,
Cap size is important as Laverda says to much makes it sluggish, less is faster but leaner this is especially true for the outlet stage, I have 20K per rail and absolutely no inductors.10K works as well just depends what you want.
 
I've never liked any sort of inductor in the supplies, including mains filters. Tried the CLCLC (and CLC and CRC) a couple of times, but always with the same mildly disappointing result.

Diodes make a marginal difference. I tend to go for low slope resistance rather than high speed.
Quasimodo snubbered my entire system, realised something was wrong. Took 'em all out again.
10KuF is plenty for main rails. Tend to use 4K7uF for other rails, but not sure what the optimum is or if it matters that much.
Transformers matter, but don't know what the rules are.
Grounding matters... a lot!

In conclusion, the simple old fashioned way is hard to improve on!
 
Good Evening All,

I did state earlier in this thread that I wanted to test out all previous modifications to the NCC200 design where I could and where it was practicable to do so.

I mention this as I try and source a transformer. On the toroid front there are three grades from Toroidy, one from Trans-Tronic, one from Tiger, one from Canterbury (although this may not be an option following the EM I received today from Terry) and a cheap and cheerful off the shelf Vigortronix pattern. Overlaid (no real pun intended) with these is that with the customs builds you can elect to have additional windings such as 0 - 42V for FE regulation duties.

There has been mention in the none too distant past about the availability of these 500VA EI pattern transformers off LesW which such as Graham has trialled and reported positively on.

I'm looking to build a stereo amplifier so do I go for one large transformer or two smaller?

Finally I need to try the separate EI pattern transformers for the FE regulation.

Would anybody care to work out how many transformer combinations there are there? Note I haven't even mentioned R or C core options............

Life is too short but I welcome people's views.

There doesn't seem to be much support here for inductors in the MiniCap6/ CAP6 boards - bit of a surprise - any supporters for them?

I am doing a lot of collating of information in the background with the intention of bringing it all into this one thread where possible. There are useful snippets all over the place.

Regards

Richard
 
Provided you have separate windings, one larger transformer is more space saving, and should sound as good.
 
Good Evening All,

Just gotten through a whole 24hrs without internet access whilst this here drilling rig was on the move.......

Managed to secure a suitable transformer from Terry at Canterbury, apparently one he had set aside for himself. It is an HN15(?) at 818VA with 2off 35 - 0 -35V @ 5A and 2off 42 - 0 - 42V @ 0.7A (c/w an electrostatic screen and GOSS band) which looks very similar to a run made for a GB on here previously:-

FgPi4sx.jpg


That could have been a lot harder.......

Regards

Richard
 
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That's a perfect transformer for a dual-mono Voyager build. Of course, that assumes you can fit everything else in the same case. You'll need a big one!
 
Good Evening All,

When you actually assemble a 5U case you 'discover' it is enor-mouse, you could surely fit two double mono Voyagers in this case????

Plan is to fit:-

1. an AA soft start board
2. the above transformer
3. 2off CAP6/ HackerCap
4. 2off MiniCap6
5. 2off VBE
6. 2off NCC200v1.5
7. at least 1off Velleman 4700\

I was looking at Ron Elliott's site and reading up about his MOSFET based speaker protection circuit and then found the Si8751 MOSFET driver chip won't be available until something like May 2023..............

I'll need to allow space for retrospective fitting of an EI transformer (2???) to power the VBE independent of the main toroid.

I really must get to bed as I've been on the go since 15:30 yesterday........ I was on nightshift and scheduled to get off the rig tomorrow but the job went without a hitch and we got kicked off just before lunch. First time on a chopper in over two years, they're still an awful way to travel.

Regards

Richard
 
I would consider strapping the the VBE and NCC200 boards on the sides, rotated so their quick connect tabs are reaching toward the center. The VBE will be in the front (with heatsink toward the back). The NCC200 would be similar, with the input stage toward the front, and heatsink toward the back.

Place the transformer near the center. The Mini-Caps6 boards could sit in front, and the main CAP6 behind. Fit the SSM and Velleman in the spare space.

You may be able to leave enough spare space up front for that eventual EI transformer.
 
Good Evening All,

When you actually assemble a 5U case you 'discover' it is enor-mouse, you could surely fit two double mono Voyagers in this case????

Plan is to fit:-

1. an AA soft start board
2. the above transformer
3. 2off CAP6/ HackerCap
4. 2off MiniCap6
5. 2off VBE
6. 2off NCC200v1.5
7. at least 1off Velleman 4700\

I was looking at Ron Elliott's site and reading up about his MOSFET based speaker protection circuit and then found the Si8751 MOSFET driver chip won't be available until something like May 2023..............

I'll need to allow space for retrospective fitting of an EI transformer (2???) to power the VBE independent of the main toroid.

I really must get to bed as I've been on the go since 15:30 yesterday........ I was on nightshift and scheduled to get off the rig tomorrow but the job went without a hitch and we got kicked off just before lunch. First time on a chopper in over two years, they're still an awful way to travel.

Regards

Richard
There are some solid state speaker protection boards available on XRK audio,I have a couple I am going to use on an amp I'm building.They are pretty compact using surface mount parts and come pre built.
 
There are some solid state speaker protection boards available on XRK audio,I have a couple I am going to use on an amp I'm building.They are pretty compact using surface mount parts and come pre built.
Yes, I've used two pairs of those in my own builds, and I really like them. They're pricey, but way cheaper than the speakers they're protecting. I've also used the cheap Chinese UPC1237 boards, but given the price I'm worried the relays are counterfeit and not to be trusted.
 
Good Afternoon All,

Just come in from cutting up a tree that landed on the Wood Shed roof during Storm Arwen because the batteries in my chainsaw have died. Time for a cup of tea.....

Only £125 a pair for the XRK boards and then there will be import duties on top.............

It would be cheaper to get Ron Elliott's PCB's and buy a couple of experimental Si8751 Development boards and de-solder the SMD chip..............

Regards

Richard
 
I'd go for Velleman's and change the cheap relays with Omron ones.

I've seen people using big heatsinks, so that they can mount the whole NCC modules in them and save space. Never mind that it's pricey, any drawbacks soundwise by not letting the output transistors get hotter ?

What is really messy with additional VBEs and transformers for these, are the cables involved. Can easily turn into a rat's nest.

Ideally, I run a 3D modeling program when too much thought is spend on placing components. It's worth the effort for precious projects.
 
What is really messy with additional VBEs and transformers for these, are the cables involved. Can easily turn into a rat's nest.

Below is a picture of one of my old Voyagers, I don't think the wiring is too bad if you plan the layout well

Voy 5 by Alan Towell, on Flickr
Alan
 
Below is a picture of one of my old Voyagers, I don't think the wiring is too bad if you plan the layout well

Yup, that's what I'm thinking, except remember that Richard needs to do a dual mono Voyager in one box, so he'll have a VBE and NCC200 strapped to both sides, the transformer(s) in the middle, and the (Mini-)Cap6 modules reaching to each side. If needs be, he can strap an SSM and Velleman on the back panel.
 
I have got four velleman boards fully built and tested by LesW that I never got round to using and are available. Also four Avondale soft starts and four Canterbury Windings 340VA toroids with separate secondaries for input and output stages. Oh and four HCR200 regulators. I really should get them listed in the diy classifieds.
 


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