Transistor equivalent

[audioguru]

My "take" on frequency response.
Everyone talks about hearing to say 15 kHz and voice is in the neighborhood of 4000 Hz.

Who says, "voices go up to only 4000Hz"? Have you ever heard about "consonants" and "sibilants" in speech? They are the high frequency sounds in speech that make it understandable. Those high frequencies are missing in a telephone which is why you say, "Huh? and What?" frequently. Consonants and silibants in speech extend up to 14kHz.

 

[KeepItSimpleStupid]

The "telephone company". My point is 4000*5 = 20,000 bandwidth which helps make 4000 Hz sound better. So, I'm actually in agreement with you.

 

[audioguru]

The "telephone company". My point is 4000*5 = 20,000 bandwidth which helps make 4000 Hz sound better. So, I'm actually in agreement with you.

in 1980 when Canada allowed competition with Bell Telephone, the audio company I worked for began selling business telephone systems. I read that a telephone line passes frequencies from 300Hz to 3kHz but when I measured a phone call out one telephone line and in on the next line the 3kHz was severely attenuated to -12dB and higher frequencies did not pass. So I complained to the phone company and was told it is normal since their spec is -15dB at 3kHz.
Then I designed an equalizer for telephone conferencing that boosted 3kHz transmit by +10dB. Each time I demo'd my equalizer then it was sold.

 

[Nikolai Petrenko]

How transistors's quality affect the sound in my amp? Fake or clone transistors able to make amp well? Sorry for my stupid question, but I don't know.
Buy components in stores which I can reach not so expensive but not sure about quality, may be a lucky game. My friend bought 2 clone EL84 tube but this tube not bad! What a lucky man!
I am thinking if transistors or others in those store will not be able to provide good sound then I will order components in some websites. What site should I go to?:
-digikey
-mouser
-.............
(for good transistors )

 

[spec]

spec:

When referring to posts, you can click on the little number and "Copy Link Location". i.e. post 597 = https://www.electro-tech-online.com/threads/transistor-equivalent.146091/page-30#post-1244315

You can also do it this way:

Post #597

using [url=https://www.electro-tech-online.com/threads/transistor-equivalent.146091/page-30#post-1244315]Post #597[/url]

One thing I hate about BB's is that the links don;t expand on printing. Printed pages are sometimes useless.

Thks again Keep- very helpful info... as usual

 

[spec]

in 1980 when Canada allowed competition with Bell Telephone, the audio company I worked for began selling business telephone systems. I read that a telephone line passes frequencies from 300Hz to 3kHz but when I measured a phone call out one telephone line and in on the next line the 3kHz was severely attenuated to -12dB and higher frequencies did not pass. So I complained to the phone company and was told it is normal since their spec is -15dB at 3kHz.
Then I designed an equalizer for telephone conferencing that boosted 3kHz transmit by +10dB. Each time I demo'd my equalizer then it was sold.

Simple, but brilliant!

 

[spec]

How transistors's quality affect the sound in my amp? Fake or clone transistors able to make amp well? Sorry for my stupid question, but I don't know.

Not stupid question- no question is stupid. Transistor quality, especially output power transistors, affects amp quality in every way possible: distortion, power output, current output, reliability. You can easily check the main chareacteristics of transistors yourself. but you cannot easily check the long-term reliability.

Buy components in stores which I can reach not so expensive but not sure about quality, may be a lucky game. My friend bought 2 clone EL84 tube but this tube not bad! What a lucky man!

Most items are OK, even Ebay

I am thinking if transistors or others in those store will not be able to provide good sound then I will order components in some websites. What site should I go to?:
-digikey
-mouser
-.............
(for good transistors )

Many, many good suppliers: Digikey, Mouser, RS, Farnell, CPC, Maplin ...

If you are going to buy from first-line retailers, let me know as soon as possible, because then we can use different components to increse the performance of the amp, without much increase in cost.

 

[spec]

no aluminum sheet thicker than 2mm, only soda cans and alum door skeletons, some thick alum pieces but too small. I even thaught to do like you approach before because too easy but I realized that thịk alum sheet not available.

You can get 2mm thick ally sheet?

What are door skelitons like? can you show image?

What are thick aluminium pieces, but too small, like? can you show image?

Window frame sections?

Any other aluminium items- there must be many used in Vietnam: old pots and pans, scap microwave, fridge, freezer, computer... Please find and list.

Motor car aluminium parts- scrap from local garage?

 

[spec]

Bad news: I was suggested by my friends that don't buy 10000uf caps because many of them are fake. Real capacitance only 2000-3000uf but look very big because caps have a thick layer of bitumen inside. They said me that I should buy 2200-4700uf caps then connect them in parallel (6800-10000uf caps certain good very expensive about over half of price the subwoofer). Well, a "capacitors bird cage" will appear in my amp.

Your friends are switched on and know their stuff: many 2.2 mF capacitors in parallel would be excellent- better than just one big capacitor. 10 x 2.2mF on each supply rail of 70W amp... nice.

Incidentally, you can easily check the capacitance of a high value capacitor with:
9V battery
resistor
switch
voltmeter (10V range)
watch with seconds display

https://www.electro-tech-online.com/threads/funny-images-thread.130358/#post-1082866

**broken link removed**​

 

[Nikolai Petrenko]

Your friends are switched on and know their stuff: many 2.2 mF capacitors in parallel would be excellent- better than just one big capacitor. 10 x 2.2mF on each supply rail of 70W amp... nice.

Incidentally, you can easily check the capacitance of a high value capacitor with:
9V battery
resistor
switch
voltmeter (10V range)
watch with seconds dosplay

https://www.electro-tech-online.com/threads/funny-images-thread.130358/#post-1082866

**broken link removed**​

Yes, it must be cheated, 10000uF also has "brand" negative .
so I need total 20x2200uF caps?

 

[Nikolai Petrenko]

You can get 2mm thick ally sheet?

What are door skelitons like? can you show image?

What are thick aluminium pieces, but too small, like? can you show image?

Window frame sections?

Any other aluminium items- there must be many used in Vietnam: old pots and pans, scap microwave, fridge, freezer, computer... Please find and list.

Motor car aluminium parts- scrap from local garage?

Sorry to say nope. Thoose aluminum are junks, door skeletons are under 1mm thick and have a styrofoam layer inside. I say that only casting, not any other way unless I lucky.

 

[Nikolai Petrenko]

Not stupid question- no question is stupid. Transistor quality, especially output power transistors, affects amp quality in every way possible: distortion, power output, current output, reliability. You can easily check the main chareacteristics of transistors yourself. but you cannot easily check the long-term reliability.



Most items are OK, even Ebay



Many, many good suppliers: Digikey, Mouser, RS, Farnell, CPC, Maplin ...

If you are going to buy from first-line retailers, let me know as soon as possible, because then we can use different components to increse the performance of the amp, without much increase in cost.

Yes, I agree to buy online

 

[spec]

Sorry to say nope. Thoose aluminum are junks, door skeletons are under 1mm thick and have a styrofoam layer inside. I say that only casting, not any other way unless I lucky.

Are you sure no ally- where I live there are mountains of ally.
Can you get steel sheet around 2mm and 1mm thick?

 

[spec]

Yes, I agree to buy online

Wow- you will have an audiophile amplifier now!

 

[spec]

Yes, it must be cheated, 10000uF also has "brand" negative .
so I need total 20x2200uF caps?

20 x 2.2mF for PSU and 2 for each amp = 3 * 2= 6. Thus total 2.2mF caps required = 26.

But if you buy from first-line retailer you could go back to 4 * 10mF: better from a practical point of view really.

 

[Nikolai Petrenko]

Are you sure no ally- where I live there are mountains of ally.
Can you get steel sheet around 2mm and 1mm thick?

steel ok! but poor heat transducer

 

[Nikolai Petrenko]

don't worry I will cast the heatsink, can you give me the size? I can do it on my traditional lunar new year, I will at home for 10 days so have enough time to do. If complete, I will post image about it.

 

[spec]

steel ok! but poor heat transducer

True, but it still conducts heat:

https://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html

don't worry I will cast the heatsink, can you give me the size? I can do it on my traditional lunar new year, I will at home for 10 days so have enough time to do. If complete, I will post image about it.

Casting will be excellent. Will post size- better start collecting ally cans! Look forward to seeing your casting

 

[spec]

One question, could you cast the whole back panel of the amp in one go, if the fins were thicker. The size would be around 18 inches wide by 4..5 inches high. The fins would be around 2 inches deep. The back panel can be as thick as you like to prevent cracking. Air bubles should not be a problem.

 

[Nikolai Petrenko]

One question, could you cast the whole back panel of the amp in one go, if the fins were thicker. The size would be around 18 inches wide by 4..5 inches high. The fins would be around 2 inches deep. The back panel can be as thick as you like to prevent cracking. Air bubles should not be a problem.

Not a problem but I worry that free space will not large enough to mount RCA jack, headphone jack, binding post if there are too much fin. So amount of fins must be suit