Class T(ea) with AMP-3

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#63
If anyone is interested in the DIYfidelity resistors they do accept paypal payments. I'm getting one!😎

It seems to be stereo because on the second page of the assembly instructions it shows two in and two out pins, but there is only one ground... is this OK?

Oh, and thank you for the nice, detailed suggestions!
 
#65
To IndyAudi

This is stereo attenuator


To Nuuk

I've checked on Australia Post site and postage (economy air) to UK is A$8. Same postage for US.


To Kanaddict

First step doesn't have series resistor, just 1 paralell to GND, thus 22*4+2=90

The attenuator is not silky smooth as DACT (in mechanical terms), but it's not bad either. Just a tad notchy. Sound is very,very good. It's mutch better than ALPS and lightyears ahead of any graphite pot.
 
#66
vmac011 said:
To IndyAudi

The attenuator is not silky smooth as DACT (in mechanical terms), but it's not bad either. Just a tad notchy. Sound is very,very good. It's mutch better than ALPS and lightyears ahead of any graphite pot.
Click to expand...

Thanks for the information !
From what you said, I suppose that the mechanical lack don't have any effect on the sound. No noise when you turn the knob. It's more about the feeling you get when using it.
 
#67
I've just ordered a 25K attenuator from DiyFidelity using Paypal! I doubt that there is any audible difference between the 25K version and the 10K that I have already but it's interesting to find out! 😉

Thanks to whoever originally spotted this great deal! 🙂
 
#68
I ordered the 50K one because that's what Jan from 41 Hz (to whom I bought the AMP3 kit) says it's suitable... Should I just change my order? What difference can it make to have 10, 25 or 50 😕 The sound volume will just increase faster or slower at each position of the attenuator or is there more to it? If someone can clarify this so that I can still chage my order if necessary, as they will only be shipping monday.

Thanks
 
#73
vmac011 said:
The attenuator is not silky smooth as DACT (in mechanical terms), but it's not bad either. Just a tad notchy. Sound is very,very good. It's mutch better than ALPS and lightyears ahead of any graphite pot.
Click to expand...

Could you please tell me what is the diameter of the attenuator (once the resistors are soldered). I have to verify if it will fit in the case I wanted to buy.

Thanks !

Daniel
 
#74
vmac011 said:
The attenuator is not silky smooth as DACT (in mechanical terms), but it's not bad either. Just a tad notchy. Sound is very,very good. It's mutch better than ALPS and lightyears ahead of any graphite pot.
Click to expand...

I have found Dale resistors to be very clean and neutral sounding so am not surprised at your post.
Years ago the DACT attenuators also were very notchy. I fixed them by putting in lighter detent springs. Later Elma offered this as an option on there switches and DACT has used this lighter version ever since. I would think the same fix could be done to this switch. Just make sure the springs are equal if it uses 2 and strong enough to keep it from hanging between positions. While you have it open spray the inside liberally with WD40 and it will keep working properly for many years.
Roger
 
#75
#76
Oops!
Forgot the picture. Here 'tis.
 

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#77
vmac011 said:


The attenuator is aprox. 40-45mm in diameter. There are two ways of assembling.
1. as shown on DIYFidelity site http://www.diyfidelity.com.au/product_info_more.php?assembly=attenuator_assembly2.php&products_id=32
2. as per picture below. This way you save few MM in diameter.
Click to expand...

Thanks !

I'll ask them to solder it for me. They charge $20.40 AUD. Knowing me, it would take me more then hour to sorlder it and make sure that each value are at the right place. So, one hour of my time worth the extra $20.40 AUD :smash:

The attenuator would fit in the case I saw last fryday in a surplus store ($10) . It's a stong metal case that would need an appropriate face plate. For my GC chassis, I used a video recorder case and I made the face plate with wood and it look very good. This time I'm stugling with myself, doing the same kind of DIY chassis or buying a nice chassis. A DIY chassis would cost me about $30 and an aluminium chassis with the knobs would cost me about $130. Making the chassis, I would save $100, but the amp won't look so good 🙄 There is not much peoples who see my system....if I buy the nice chassis, it would be for my own pleasure 😉

Thanks again !

Daniel
 
#78
There was a very thorough discussion about these Dale-based attenuators a while back when everyone was making Gainclones.

A lot of folks got really excited about them because the offered very good performance for the price. As people started buying and using them, though, many discovered that the switch would often produce loud popping/ electrical switching noises when switched (and not necessarily at all rotational positions) that, when amplified, was sufficiently annoying that they eventually switched to something else. It was even determined that the switches were make-before-break types, so the culprit was thought to have been contact damage from excessive heat when the technician assembled them.

There was some fear, as well, that the loud pulse could damage high efficiency speakers.

I bought one of these before all this came to light, but I haven't had the chance to use it, yet.

It would be very useful to hear if anyone is still experiencing this type of popping on the more recent units being purchasing.

Apart from the popping, these attenuators were said to sound very good.

Best,
KT
 
#79
Popping noises

The noise is generated from a voltage transient being generated and fed to the input. This can be caused by 2 things;
1) There is DC present on the volume controls input,
2) The switch opens up while switching between steps.
1 can be fixed by tracking it down and eliminating the source. A quick and dirty solution would be to add film caps into the path before the control.
2 can be fixed with a good replacement that doesn’t open up or a 27k res. can be added from the output to ground thus preventing it from ever opening all the way.
Roger
 
#80
sx881663 said:


I have found Dale resistors to be very clean and neutral sounding so am not surprised at your post.
Years ago the DACT attenuators also were very notchy. I fixed them by putting in lighter detent springs. Later Elma offered this as an option on there switches and DACT has used this lighter version ever since. I would think the same fix could be done to this switch. Just make sure the springs are equal if it uses 2 and strong enough to keep it from hanging between positions. While you have it open spray the inside liberally with WD40 and it will keep working properly for many years.
Roger
Click to expand...

Does the WD40 have good electrical characteristics?
 
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