Class T(ea) with AMP-3

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#41
To knob or not to knob that is the question.

Nuuk said:
Nearer home is CPC in England with quite a good range of connectors.

Forget the pot and do the amp justice with a stepped attenuator! 😉

And big knobs are a bespoke item so don't expect to find one off the shelf. You will need to find a friendly local person with a lathe! :att'n:
Click to expand...

Nuuk,
Right on the money! Stepped attenuator is the way to go.
The knob issue is why I bought a small lathe. Even designed and built a radiusing attachment for it. Love the feel of heavy brass knobs with smooth edges. Now if I can figure out some way to get the plating done without it’s costing a fortune.
Roger
 
#42
Hello,
Do check at http://www.hificollective.co.uk/components/potentiometers.html for pots. They've got good pots and better still a ladder type Stepped Attenuator with Dale Vishay resistors, hush it's a secret...
That was exactly what I was looking for ages and I ordered one from them...its on its way.
Its the best you can get except if you want to go the Transformer Volume Control way... the Holy Grail
But this cost leg and arm. Does anyone know non-expensive TVC source (I won't say cheap with all that implies) please share but I suspect there ain't any. But I don't despair.

They also have Elma switches and Audio Note knobs that look gorgeous. I'll order them soon to make a passive pre.
Cheers.
 
#43
TVC

Just a note: I have only checked out one TVC on the bench and it was truly a disaster. It had extreme ringing with sq wave input on all settings but one. This particular unit came from China but wasn’t all that cheap. Be real careful of these and be sure you can return them for your money back if you don’t like them.
The stepped ladder looks real nice and at a fair price too. With only one resistor to the input at any settings it should be very nice sounding as well. Only disadvantage I can see is the large size.
Roger
 
#47
Hi,
I do think it makes sense to put a good pot on a good amp.
And of course the amp is worth more than 20 pounds when you consider the effort and time (and fun) in the soldering and assembly.
Good connectors by themselves may cost more than the amp.
And we are not talking about the power supply.
I have seen passive pre-amp with only input selector and attenuator in the $1000 price, so...
 
#48
I agree with MrDodo here! Any hi-fi system is only as good as its weakest link!

I can think of lots of other things that will cost more than an attenuator and not improve the sound quality as much!

And besides, if you fit a 50 UKP volume control to a 20 UKP AMP-3 then surely you have a 70 UKP amp, not a 20UKP one. :att'n: 😉
 
#49
MrDodo said:
Hello,
Do check at http://www.hificollective.co.uk/components/potentiometers.html for pots. They've got good pots and better still a ladder type Stepped Attenuator with Dale Vishay resistors, hush it's a secret...
Click to expand...

What do you think of this one :

http://digitalanaloguediy.com/attenuator.html

they have a 10K and a 100K. I wonder if one of this value would be a good choice for the autocostruire 2020 kit ?

Nuuk

What is the value you use with your autocostruire amp ?
 
#54
Those stepped attenuators using the dale resistors are nice units,
they are certainly much better than the Noble or Alps blue pots (already compared them).
I've just fitted mine inside a little case with in/out phono sockets and teflon/silver wiring, it makes a nice passive pre😉
 
#55
to brush or not to brush...

A little question a bit off the topic... I can probably get hold of a thick aluminium plate that would be ideal for the front pannel of my on-going AMP3 based project. However, this material has an ugly, kind of polished finish.. how can I make it look like brushed aluminium? Just scrub it with coarse sand paper for metal? Any ideas?

Paulo.
 
#56
brusha, brusha,--- brusha

Paulo,
There are many finishes you can do. One I like is to put a Scotch brite green scrub pad on an orbital sander and have at it. Place the panel on a rubber pad so it won’t move around while you sand it. Use even, straight across strokes to begin with. If you do use sandpaper start with 400, this is so it won't mess the panel up too much if you don’t like it. Working at metal finishing is a time consuming art and requires a great deal of patience. Doing it with a hand block and sandpaper will never be uniform but a hand finish can be done using the Scotch brite pads with a block. This finish won’t last and will start to deteriorate immediately, you will need to have it anodized when it is done to protect it. The finish will be smoother after the anodization as some of the surface etches away. A 600 finish will be almost shinny after it is anodized. An alternative after the finishing is done is to scrub it with dish soap and hot water, rinse very thoroughly in the hot water, dry, then do a transparent clear lacquer over coat. This is not very durable and I wouldn’t recommend it except for something quick and temporary.
Note; this is dirty work and will stain clothes. This will make your better half very unhappy so wear old ones.
Roger
 
#58
IndyAudi said:


I don't wish to confuse the issue but aren't those Oz stepped attenuators @ 49.5 AUD only mono ?

http://www.diyfidelity.com.au/product_info.php?cPath=0_33&products_id=32:
Click to expand...


Well, it use a total of 90 resistors. It have 23 steps with 2 resistors each = 46 resistors. From this I can conclude that there is 45 for one channel and 45 for the other. I don't know why the stepped attenuator dont use 46 on each side 😕 Maybe someone can explain this to us 🙄

Regards,
 
#60
A little off topic not not much as we are in the pot subject, I've got an old Morganite 10k pot from the scrap bin and always wondered what was the connections at the back of the pot is for.
It's written 2A - 250v.
 

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