UK Aleph-X PCB orders

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#222
CAPACITORS

BP

I think we need to sort out caps.............I think the best way to do this is actually ring the US and place an order that way.....
you can ensure there is stock + price & pay in one go.....I did this for Conrad order.....

D3
 
#225
Ok, I think I now might have a reason why I haven't heard back from BG rgarding the caps we wanted... as they are no longer listed on their site Iguess we missed them (****).

So, we now have two options, there are still the mini caps, rated at 15,000uF and 35V on the BG website for $1.49. However, I also found some other rather nice looking caps on a differnet site. There re two options, one 46,000uF at 20V for $2.50 or a huge 90,000uF at 20V for $7.95.

Now, I realise that most people here seem to be set on the idea of going with 18V secondaries to build up monoblocks, so for you guys this would be too low a voltage (at least on the big ones), but, if you were to go with 15V or lower these may be a possibility for the PSU caps (you would still need to drop a bit of voltage through some resitors).

I also have seen some 30V 36,000uF caps here in the UK for a not unreasonable price of £5.75 which could be a useful backup if we cant find anything better.

If people let me know what they would like to do with this I can try and sort someting out, but for now sorry that I wasn't quick enough to get the other ones in the first palce.

Andrew.
 
#226
Oh, I almost forgot.

If I get a spare few hours in the next week or so, I may have a look at designing a transitor testor to try and match the specs up as per the Pass labs sujestions.

If anyone else feels inclined to have a look at this first, let me know, so I can try an learn some more for my exams (not that I actualy want to at teh minute) instead.
 
#230
CONRAD HAS LANDED!!!!!

Hi............I have just recieved......conrad order all 25Kg's......I
can hardly move the box!!!! Haven't opened it yet.

All the custom's copies of the fedex order - are still with the package.....and it has 'cleared' stamped on the box......I am hoping......we will not have to pay vat or duties...........I guess I will be sent a letter....if that happens I will let you know costs.

I will open up box tomorrow morning........and let you know...

I will aim to sort posting at the weekend....will keep you posted.

Richard😀 😀 😀 😀 😀 😀
 
#231
Hello

For an estimation of what it will cost to post our sinks out to us you can use the royal mail website.

Standard parcel post is on this page here

http://www.royalmail.com/portal/rm/jump2?catId=400028&mediaId=400031

I am assuming that my 4 heatsinks, when packaged will weigh roughly 10kg which should cost £9.23, not too bad really. Plus of course any costs for packaging that D3 will have to buy as well.

Looking forward to getting these things deliverd. 🙂

Mark.
 
#232
WIKI

Good to see the WIKI has already been visited!! 🙂

I have had some interesting calls today - PinkMouse's supplier link.

A bit late now, but I'll post the prices tomorrow. I think discretion would be in order, as you'll agree when you see the price-range!! :bigeyes:

At the moment, the Reichelt / Schuro buy seems pretty good value.

Cheers

Jon 🙂
 
#233
Tranny group Order from Airlink ??

Hello Guys, Jon in particular,

Allow me to drop by, since I am also from the U.K. but job takes me to Oberkochen for the time being.

Before you guys would order toroidal transformers from Airlink, could I suggest someone to get in touch with Mike Novak of Avery Magnetics, an associate company with Airlink but specialises in Audio Transformers. I had a long discussion with him a while ago, and I am sure he will tell you guys as well what he can offer and how that differs from Airlink and Piltron (e.g. using MOH cores instead of M4 and M3, the former having much lower losses at higher flux density, etc. (His email address is miken@avmag.com but you probably get more info calling him directly.)

Avery does not have standard products, which means one has to pay a setup charge. That is why I have still not ordered anything from him yet. But since there seems to be enough people interested in toroidals, I am sure there would be no problems getting the quantity (say 50), which will make the setup charge effectively a few pounds. The Avery toroidals are then still some 50% more expensive than the Airlinks ones, but still very good value for what you get, especially compared to Piltron imported.

If you guys decide to go ahead, and would go for 1000VA, 2 x 23 V secondaries on 230 V primary (note that Nelson runs his 15W Aleph-X from First Watt at +/- 25 V rails and not + /- 15 V as in Grey Rollins' schematics), then please count me in for 3 transformers. I can provide an address in the UK and bank transfer from Barclays, no problem.

Otherwise happy shopping in Germany. You have already found the right places. And do have a look at the Vishay Dale resistors (0.1%) and MPC71 4W metal foil power resistors from Schuro (www.schuro.de/preisl-mpc71.htm). The latter are a real hit in Audio DIY in Japan. Great as source resistors and very affordable.


Cheers,
Patrick
 
#235
TRANNYS

Yep I agree.......however I am busy today....I will try and email avery later today ...... and find out the bottom line costs for
say 20 transformers...............

EUVL would like 23-0-23.................what does the group think...
take a look @ his response.......it may pay us to alter 18-018 spec.

D3
 
#236
Transformer ratings

If the voltage strays too far from 2 x 18v windings then it's going to mean me loosing too much off the top - i'm looking for +-18.5 to 19v rails at the FET's.

I'm sure the Avery transformers are better but i need lots of them (10 off) and they're going to cost much more, so there needs to be a justifiable benefit to me in doing this.
 
#237
Trannys

Jason.........I fully understand.........I will still get info then we can
decide.............however I think you are right.........lets wait and see.....

I think I am right in saying that we don't need mega low impeadance.........like class a-b amps .... so maybe its not critical in anycase.....in which case our proposed trannys will be fine....:bigeyes:
 
#238
Rail Voltages

On the topic of rail voltage :

I have actually built one channel of the Grey Rollins' layout on +/- 15 V rail after CRCRC (CLCLC has too much stray magnetic field to worry about, as far as I am concerned). The sound is gorgious, beats my Krell KAV300i, but it is crying for more power to have the bass under control. Believe me, I have been listening for 2 months, and we made a blind test in Oberkochen with 6 people, comparing Krell, Aleph-X, and JLH 15W (two amps driven in differential mode to make one channel). Aleph-X comes out on top, just beating JLH.

For me, the only reason to go for 18V secondary (which will probably give just under 20V after the caps) is to drive the speakers active, i.e. active crossover and then one amp for each speaker chassis -- exactly what Grey is using his. Then probably +/- 15V is sufficient for high and middle, and you need a class AB (like gain clone) to drive the bass. But how many of you are going active crossover ??

And unless you use IRFP044, I would check out the FET testing article by Nelson, especially on distortion against voltage and current. He uses 25V 1A bias on IRF240's, for good reasons. Get yourself a few different transistors, bias them with different current and voltages, and measure for yourself linearity and noise. Anything else is speculation. I am actually planning to test other non-IRF transisotrs. But they are bloody expensive. So they need to be much better before I change my mind.

Personally, I would not come under 1kVA. You save little space and money if you are building two mono-blocks, and many of you would want to have more power once you get the first one going. Also have a look at what power supply they use for the Hiraga Le Monstre 8 W Class A. I think an Avery 1kVA would cost probably 40 to 50 pounds on quantity. I actually looked around quite a bit in Germany. A lot of people here buy from Tauscher, which is much larger in size, uses M4 laminations instead of the hydrogen annealed MOH, and still costs over 80 pounds per transformer.

But ask Avery first, and let him give you an impression as to whether he knows his stuff. Then decide what you really what and whether there might be a bit of truth in what I said.

As I said before, count me in for 3 pieces if you go for 1kVA, 23 / 23 secondaries.


Patrick
 
#239
TRANNYS

Q. The power output I have calculated for 18v tranny is in the region of a conservative 100w in to 4 ohms this is with 8a bias.

Is this not enough power generally to lift the roof in an average
room with average efficency speakers?

I currently use 50w VTL monoblocks..........they are very powerful
and fill the room with ease.........

My intention was to double the headroom..........to allow flexibility....

What are your views????????
 
#240
Transformer Ratings

D3,

Could we not address you by first name at least ?

Before we get to the transformer, the discussion first is what rail voltage for the amp. You are right in a sense that if you can get the theoretical maximum peak 25V from 18V rms secondaries, then you would have no problems getting 100W in 8 ohms. But that I think is a bit optimistic. You will have losses in transformers, diodes, and if you use CRCRC, then in the resistors. I don't like to have unnecessary stray magnetic fields around, and if you don't want to pay 200 pounds for capacitors, then you have to increase R, raise rail voltage and generate heat to get the ripple voltage down. Of course you can also use regulators or capacitor multipliers, and get some high frequency noise from the serial pass device (whether Mosfet or BJT) in the process.

The other thing is how you calculate output power from rail voltage. In the excel sheet in the Aleph thread, it was assumed that you can get to within 2 volts from rail before clipping. This is theoretical true. I assume 5V from rail as clipping, and with +/-26.5 V rail, 7.7A bias, I get about 100W at both 4 and 8 ohms, peaking at about 120 at 6 ohms. All speakers with nominal 8 ohms can go as low as 3 ohms at certain frequencies. So be aware.

Do you ever need 100W, no, not in a house of reasonable size. But it is all about reserve and control. As I said, I built the 15W version, which quite happily drive my Nautilus 804's, loud. But there is just not enough control at low frequencies compared to my Krell. So I want 100W, just as you do. The difference is how to get there.

I am not trying to convince you guys to change your mind, or you will blame me for that if anything goes wrong. I have told you, openly, what I am planning to do for myself. And if there are enough people thinking of taking the same route, then let's join force and get something decent for a reasonable price. If not, I'll go it alone anyway.

Patrick
 
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