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Courtiestown - Naim Amplifier (Avondale) Upgrade Project

Richard Lines said:
As you read through the threads you find the occasional contradictory statements. Do the VBE's drop 2 or 4V??
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There's likely a minimum drop, but the whole point of the VBE is to regulate even lower. In the case of my Voyagers, I have a 50-0-50VAC transformer producing around ±70VDC into the VBE's input. It regulates it down to somewhere between ±50-55VDC, so it's dropping 15-20V. You'll have to ask Les whether dropping it this far is necessary/best.

For example, the input stage of the NCC300 has built in regulation, and you adjust that to be 5V less than the input voltage. Having some headroom is a good thing when regulating voltage.
 
Good Evening All,

Spoke with Gavin at AA this afternoon and clarified a few things. The 61.5V in to the HCR will be OK, the latest HCR's come with 100uF/ 100V Nichicon inlet capacitors as opposed to older versions which I believe were fitted with 63V Nichicon's.

Only the transformer CT's need to go to the inlet of the CAP6. I need to clarify the situation with the speaker negative as I forgot to ask.

I asked about the supply of heatsinks for the rectifiers on the older CAP6 PCB's, TO-220 and main heatsinks for VBE PCB's and the availability of transformers to supply VBE's.

Gavin's M130's are en route courtesy of UPS (rather than the first attempt with Herpes). This will allow me to get the hi-fi system up and running again whilst I experiment with the 'sacrificial' NAP250. Graham's case is now also 'en route'. Fingers crossed that Alan's transformer will eventually find its way here (utilising a courier other than Herpes). Then maybe I can start building a 'Voyager' type clone............

Regards

Richard
 
Richard Lines said:
Spoke with Gavin at AA this afternoon and clarified a few things. The 61.5V in to the HCR will be OK, the latest HCR's come with 100uF/ 100V Nichicon inlet capacitors as opposed to older versions which I believe were fitted with 63V Nichicon's.
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I spoke with Les earlier today myself, and he also confirmed that the HCR200 can take more than 60V. I've just checked, and the HCR200 I have here does include the 100V input caps.

Richard Lines said:
Only the transformer CT's need to go to the inlet of the CAP6. I need to clarify the situation with the speaker negative as I forgot to ask.
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The general wisdom is definitely to connect the speaker negative to the "dirty" end of the CAP6, with the transformer CT.
 
Good Evening All,

Well that's the CAP6 'fully' installed and the amplifier back in service, pending the arrival of the M130's.

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Q0OzMBJ.jpg


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I've moved the CT connections to the CAP6 inlet along with the speaker negative. There are two green wires coming from the speaker negative. I'm assuming I can just remove the 'extra' one. I still have to sort out the LED wiring.

Once the M130's arrive I'll be putting two NCC200's into this amplifier.

Regards

Richard
 
I didn't realize you had kept the ground bar between the speaker negative posts. With that original configuration, almost everything is grounded to that one point. Now that you have a CAP6, I suggest you remove it and do this:
  • Transformer CT goes to the CAP6 dirty ground
  • CAP6 dirty ground goes to the speaker output grounds
  • CAP6 clean ground goes to the HCR200 input grounds
  • HCR200 output grounds feed two grounds on each the NCC200
As it is, I highly suspect you have a ground loop (and associated hum).
 
Mike,

No hum - possibly more by luck than judgement? The keeping of the negative bar between the speaker posts wasn't intentional more a lack of knowledge.

I also noted the previously noted 61.5VDC output from the CAP6 was showing as 60.5VDC.

Regards

Richard
 
As Mike says the 250 traditional earth point at the speaker posts is a well known area for tweakers, the speaker earth should always go to the cap6 for optimum performance but it won't cause any hum issues if you don't.I use hackernap boards which are similar and everything goes back to one common earth point via that board always sounded best that way.
Earth routing always perplexed me till I saw a description by a designer as a set of tributaries of a river joining to an estuary then the sea, as long as one doesn't back up another then it's good, current should always flow unrestricted in one direction.
Geoff
 
Good Afternoon All,

Been into town this morning, principally to collect the Zoe which had checked out OK yesterday and showed exactly the same error message when the garage went to drive it round for me to take away so we then went to an, unplanned, Plan B.

Collected the M130's from the flat;

v2HBbQY.jpg


These will shortly take over from one NAP250.

Also courtesy of a very efficient eBay seller the transformer I bought only the evening before last was here when we got back. Contrast this with the saga over Alan's device via Herpes......

ixhUpKS.jpg


Still waiting on hearing back from AA about VBE and assorted bits.

Regards

Richard
 
QUDOS mono amps. Nice!

I notice that they have the speaker grounds coming from the clean end of the CAP6. Avondale does take both approaches, but I think they usually go from the dirty end.
 
Mike,

Gavin said something about keeping things one end or the other when I spoke to him the other day.

AA have confirmed they no longer have any VBE transformers. The only stockist of anything vaguely suitable would appear to be RS - https://uk.rs-online.com/web/p/chassis-mounting-transformers/0504066 although these are on back order the 100VA versions are in stock.

Here's another picture from today. I made a foul-up in my order for hook-up wire and managed to order two reels of orange so placed an order yesterday for the correct red I required for collection at the Aberdeen branch. I'll ignore the fact they have yet to confirm despatch or the availability for collection yet but this is the box used:-

TDAnsW8.jpg


There was nothing else in the box, not even packing. On the positive side at least it was there to be collected.

Regards

Richard
 
Richard Lines said:
Mike,

Gavin said something about keeping things one end or the other when I spoke to him the other day.

AA have confirmed they no longer have any VBE transformers. The only stockist of anything vaguely suitable would appear to be RS - https://uk.rs-online.com/web/p/chassis-mounting-transformers/0504066 although these are on back order the 100VA versions are in stock.

Here's another picture from today. I made a foul-up in my order for hook-up wire and managed to order two reels of orange so placed an order yesterday for the correct red I required for collection at the Aberdeen branch. I'll ignore the fact they have yet to confirm despatch or the availability for collection yet but this is the box used:-

TDAnsW8.jpg


There was nothing else in the box, not even packing. On the positive side at least it was there to be collected.

Regards

Richard
Click to expand...
I bought a couple of multi comp EI transformers from RS for my Paradise Phono stage power supply which were 230VAC and the hummed quite audibly I tried mounting them on a rubber support and taping the laminates but it didn't help so I changed them for the telema encapsulated type and they were are still silent (but only25VA)
The ones you posted are RS pro types so may be better ?.

Paradise power supply by Alan Towell, on Flickr
IMG_4534 by Alan Towell, on Flickr
Alan
 
I have a couple of Hammond 167J100 (50-0-50VAC 100VA). I bought these with the intent of using them in my Voyagers many years ago, but when ordering a bunch of other stuff from Avondale, I made an executive decision to get their recommended units. That left me with two perfectly functional transformers without a suitable project.

Unfortunately, they wouldn't work for you, Richard, as they support only 115V mains.
 
Mike Hanson said:
QUDOS mono amps. Nice!

I notice that they have the speaker grounds coming from the clean end of the CAP6. Avondale does take both approaches, but I think they usually go from the dirty end.
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I have stated a few times. The neg 'may need' to be clammed to the clean end of the CAP6. I have found it to be transformer dependant. But try either way you'll soon know which is best.
 
Good Evening All,

Having had to cobble together a RCA to RCA cable to get the M130's integrated and having satisfied myself with regards to 'offset' they're now in place and forming part of a 7 pack driving the Isobariks. Things are a little unbalanced as the the M130's are driving one bass and midrange unit on the left I probably need to get them driving one bass unit each side??? More re-wiring required of assorted Neutriks/ RCA's....................

Looking for an absolute wall of sound try Disturbed's live version of Sounds of Silence - there's still things to be extracted from these Isobariks...............

Next up will be putting a pair of NCC200's into the already modified NAP250.

Regards

Richard
 
Good Afternoon All,

I was quite surprised that one of the small Allen headed countersunk screws didn't want to come out of one of the original heatsinks this morning. Tried some heat from the solder reflow machine and this didn't help. The tried a hammer and a centre punch and that didn't work either so had to resort to drill the d**n thing out. Grrrrrrrr.......

Things have gone better since, that's the ex Mark Slade NCC200's mounted:-

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All wired up to the HCR200's, note just the one 'earth' wire from the common speaker negative going to the 'dirty' side of the CAP6:-

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and an overview:-

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this wired as per Mike's 'instructions above. I've also removed all the 2.8mm connectors and replaced with 6.3mm versions.

All that remains now is to power it up and check bias/ offsets I guess............

There are two complete built VBE's on their way up from AA along with the heatsinks for the NCC200's. Graham's 5U case should arrive at the flat tomorrow. The only thing holding up a Voyager type build is Alan's transformer wherever that may have gotten to.

Regards

Richard
 
Looking good!

I can't quite see all the connections. I assume that:
  • The purple wire from the upper HCR200 positive is going to the positive terminal on the upper NCC200.
  • The brown wire from the lower HCR200 negative is going to the negative terminal on the lower NCC200.
Time to set/check the bias currents and offset voltages. BTW, when you check the bias voltage, make sure you leave it running for at least 15 mins (preferably 30 mins or more), as I've found the bias can take a long time to stabilize. Granted, that's more of an issue with a larger heatsink. In this case it's just using the base plate, so it will warm up to steady state faster.
 
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