# Going tubes...

#### oemcar

##### Member
A long time ago, new solid state amplifiers produced odd-numbered harmonics but tubes produced even-numbered harmonics that old people think was in the music. Now old people like the harmonic distortion produced by tubes better than having no distortion.

The buyers guide has no spec's. Maybe the output transformers in the tube amplifiers muffled high frequencies and hiss the music?

It is normal for men to have high frequency hearing loss beginning when they are only 20 years old without playing with guns and loud acid rock noises.
At 65 years old, a man does not have golden hearing, instead he can barely hear any sounds above 4kHz like in this graph:
Since you are longer in the tooth than I... your inference of hearing loss due to my age is 3 fingers pointed back at you...

Personal insults are not helpful in this discussion- imo.
Jim

#### oemcar

##### Member
Constructively,
I purchased this Chi-fi product-

Again,
I chose this design cuz it's Class AB push pull, which is twice as efficient as single ended class A. I like that sine (sound) overlaps in this design. Seems class A is susceptible to noise- ways to mitigate is w/ higher end design/ costlier components... and trial and error timing element.

When kit arrives- will update progress-
Jim

#### audioguru

##### Well-Known Member
Are there any detailed audio spec's for the low power Chinese amplifier kit?
Usually an audio amplifier has its frequency response, distortion and noise listed.

I notice that AliExpress sells an assembled modern 200W IC amplifier with Bluetooth. Its cost is almost the same as shipping for the tubes amplifier and it has free shipping.

Amazon sells a tube amplifier rated as class-A 6.8W per channel. Same manufacturer and same part number as the AliExpress one you are buying. Its very high distortion is listed.

Another Nobsound 6P1 amplifier kit shown in Google says 2x 4W output and they say for a professional to assemble it since it does not come with step-by-step instructions.

I wonder which one you will receive. Good luck.

#### be80be

##### Well-Known Member
• Output power: 6.8W * 2
• Frequency response: 20Hz-20KHz
• Suit headphone impedance: 32Ω-600Ω
• Input impedance: 100K ohms
• Output impedance: 8Ω,4Ω
• SNR: 90db
• Input Sensitivity: 500mv-2000mv
• Harmonic distortion: 1% (1KHz)
• Tube: 5z4p * 1 6H8C * 2 6p1 * 4
• Operating voltage: 110V or 220V
• Weight: about 7 kg
• Size: 260mm * 215mm(including terminals and knobs 260mm) * 150mm (W*D*H)
Package includes:
• Finished tube amplifier ×1
• Power cable ×1

#### rjenkinsgb

##### Well-Known Member
At 65 years old, a man does not have golden hearing, instead he can barely hear any sounds above 4kHz like in this graph:
Speak for yourself!

I can hear the frequency sweep you linked to in another thread OK up to around fourteen KHz, after a lifetime of very loud music, anytime I get the chance!

#### BobW

##### Active Member
I recently bought a hifi amplifier that has THD of 0.000000001%, IMD of 0.00000000001%, and output power of one million watts. It runs off of a 9V battery. These amazing amplifiers would never have existed if it weren't for the government getting rid of all those "stupid regulations."

#### Nigel Goodwin

##### Super Moderator
Constructively,
I purchased this Chi-fi product-

Again,
I chose this design cuz it's Class AB push pull, which is twice as efficient as single ended class A. I like that sine (sound) overlaps in this design. Seems class A is susceptible to noise- ways to mitigate is w/ higher end design/ costlier components... and trial and error timing element.
Looks a fun (and easy) kit to built, but it's a LOT of money for a low spec amplifier of very low power.

#### be80be

##### Well-Known Member
Looks a fun (and easy) kit to built, but it's a LOT of money for a low spec amplifier of very low power.
I posted the spec for about the same one just it put together and has meters added to the wax

I been playing a little bit with tubes getting them to heat up and glow.LOL

#### audioguru

##### Well-Known Member
Speak for yourself!

I can hear the frequency sweep you linked to in another thread OK up to around fourteen KHz, after a lifetime of very loud music, anytime I get the chance!
Everybody is different. The graph I posted shows typical high frequency hearing loss for different ages.
My hearing aids make good sounds up to 10kHz then are limited by feedback squealing at higher frequencies. I could ask for programming producing a flat frequency response up to 16kHz if the mics are muted but then I would miss hearing many important things.

#### audioguru

##### Well-Known Member
I noticed that the tubes amplifier has low output power and a horrible distortion of 1% at only 1kHz, probably much higher at other frequencies.
Its frequency response says 20Hz-20kHz but does not say how much peaking (+30dB?) or low levels (-30dB?).
The frequency response of a modern audio amplifier is a flat line from 10Hz to 50kHz.

Here are parts of the datasheet of the 17 years old LM3886 class-AB hifi amplifier IC selling for $6.82US at Digikey today: #### Attachments • 55.6 KB Views: 1 #### Nigel Goodwin ##### Super Moderator Most Helpful Member I noticed that the tubes amplifier has low output power and a horrible distortion of 1% at only 1kHz As you are well aware, having come from that era, 1% distortion would be common for valve amplifiers - it's not an issue as that's what people are looking for, the 'valve sound' (highish distortion and poor frequency response). #### audioguru ##### Well-Known Member Most Helpful Member I betcha the old tubes amplifier design will be used to play old vinyl records and cassette tapes, until its tubes wear out soon. Years ago I found some portable MP3 players that were thrown away. I took pieces from them and made one that works perfectly. But I do not use it because its memory is a mechanical hard drive that eats batteries. My new computer has a SS drive that boots instantly. It has thousands of times the storage that my first pc had. Remember Windows 3.1 and dialup internet at 30k? Internet and cable TV on my street is now on blazingly fast fiber optic cable. Remember old TV antennas? #### oemcar ##### Member I can hear the frequency sweep you linked to in another thread OK up to around fourteen KHz said: • Output power: 6.8W * 2 • Frequency response: 20Hz-20KHz • Suit headphone impedance: 32Ω-600Ω • Input impedance: 100K ohms • Output impedance: 8Ω,4Ω • SNR: 90db • Input Sensitivity: 500mv-2000mv • Harmonic distortion: 1% (1KHz) • Tube: 5z4p * 1 6H8C * 2 6p1 * 4 • Operating voltage: 110V or 220V • Weight: about 7 kg • Size: 260mm * 215mm(including terminals and knobs 260mm) * 150mm (W*D*H) Package includes: • Finished tube amplifier ×1 • Power cable ×1 #### oemcar ##### Member What channel are you on man?? [/QUOTE] #### audioguru ##### Well-Known Member Most Helpful Member The 12W + 12W should say at how much distortion and if it is Whats or Watts. 12W peak is only 6W continuously. The 20Hz to 20kHz should say the amount of deviation from flat. +/- 30dB is awful but +/- 3dB is OK. The 1% distortion should say at how much power output. At 0.5W? The amplifier has no cover and the tubes become very hot. Do you have pets, kids or grandkids who will be burned? #### gophert ##### Well-Known Member Most Helpful Member The amplifier has no cover and the tubes become very hot. Do you have pets, kids or grandkids who will be burned? Great idea, I'd love to be "branded" by an old RCA tube. Only it would show up as AƆЯ #### oemcar ##### Member I noticed that the tubes amplifier has low output power and a horrible distortion of 1% at only 1kHz, probably much higher at other frequencies. Its frequency response says 20Hz-20kHz but does not say how much peaking (+30dB?) or low levels (-30dB?). The frequency response of a modern audio amplifier is a flat line from 10Hz to 50kHz. Here are parts of the datasheet of the 17 years old LM3886 class-AB hifi amplifier IC selling for$6.82US at Digikey today:
If the monolithic 3886 are the design prodigy of the high end retail market-
Then show me the $20k mono block design that uses them #### gophert ##### Well-Known Member Most Helpful Member If the monolithic 3886 are the design prodigy of the high end retail market- Then show me the$20k mono block design that uses them
Whoosh!
That was the sound of a concept that went right over your head.

.

#### oemcar

##### Member
If prevailing winds of opinions here are right, then why do those 'dark' options still exist?
Accordingly- the tube amp industry should have failed long ago.. right?

But it hasn't-
And if nostalgia were the only prop, then why are those still spending upwards of \$20k on a pure or hybrid design?

For comparison- who here in objection has spent that same coin on their system? and candidly evaluated? No punk quotes- show me your spectrum analyses.

My belief?

The reason the Cancel Culture solid state mob have not destroyed the tube industry, is perhaps, because they are predisposed to #'s.
Jim

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#### oemcar

##### Member
Great idea, I'd love to be "branded" by an old RCA tube. Only it would show up as AƆЯ
Now thats funny!
But you still just dig dirt- lol!

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