Headphone amplifier on ECC88 and 6N6P that is "FARELKA"

The design looks interesting, the wooden parts came out very professional. Perhaps a metal knob would be useful?

Why do studio headphones have a higher impedance?

You've described the listening experience quite succinctly, and it looks like the noise level and overtones are at a low level.

How do you rate the bandwidth and frequency response?

Pretty neat. It's nice that something audio and tube-based has appeared in the DIY section Wooden parts brilliantly done, the fit of the whole is also flawless.
In my opinion, this black cage is a bit incompatible with the silver parts of the amplifier. Nothing else is black so in my opinion it would be better if either the grille was silver or the rest was also black. The white knob doesn't fit very well either, but I suspect it's a temporary solution And the RCA sockets on the front - not very convincing to me, I think it would be better if they were on the back, there's plenty of space there.
These black PCBs are some kind of "ready-made" or just ordered?

Regards,
A.

TechEkspert wrote:

Interesting looking design, the wooden parts came out very professional. Perhaps a metal knob would be useful?

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I just like this knob for what it is, but maybe I'll think of something!

TechEkspert wrote:

Why do studio headphones have a higher impedance?

I asked chatgpt because I didn't know myself, here is the answer:
1. precision and sound quality
- Better driver control: The higher impedance allows for more precise diaphragm control in the headphone drivers. This results in more accurate sound reproduction, which is crucial during mixing and mastering.
- Reduced distortion: In headphones with higher impedance, the current flowing through the transducers is lower. This reduces the risk of electrical distortion and produces a cleaner sound.

2 Appropriate adaptation to professional equipment
- High-impedance amplifiers: studio equipment such as audio interfaces and headphone amplifiers are designed to work with high-impedance equipment. This combination guarantees optimum sound quality.
- Greater power tolerance: High-impedance headphones can operate at higher power levels without the risk of damaging the transducers. This makes them more reliable in studio environments where high signal levels are worked with.

3. versatility in studio environments
- Works with a variety of audio sources: high impedance headphones are less sensitive to the quality of output from different devices, meaning they work better with a wide range of studio equipment.
- Better noise isolation: Higher impedance allows for more effective noise suppression from external equipment, which is particularly important in an environment full of different electronic devices.

4 Longevity and stability
- The high impedance reduces the risk of overloading the transducers, which increases the durability of the headphones in intensive studio use.

5. tonal balance at high volume levels
- Higher impedance headphones can better maintain tonal balance at high volume levels, avoiding overly boosted lows or highs.
ps. please someone knowledgeable on this subject to confirm or deny the words of the bot.

TechEkspert wrote:

You have described the listening experience quite succinctly and it looks like the noise and overtones are at a low level.

How do you rate the bandwidth and response characteristics?

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I haven't measured the noise and hum levels, nor the characteristics, but I plan to do so at some point.

From a design point of view: at the input of the ECC88 there is a low-pass filter built from a 100pF capacitor(plus tube capacitance) and a 10k grid resistor. In front of the grid stopper there is a 50k potentiometer, which in the middle position (i.e. with the highest resistance in series with the grid stopper 10k + 25k = 35k) passes the bandwidth up to about 25kHz which is a little more than the audio frequency. At the output of the amplifier (cathode secondary) there is a high-pass filter made up of a 100uF capacitor and a 10k resistor which, with 250ohm headphones connected, passes frequencies from about 6.5Hz at a load value of about 244 ohms (10kII250ohm).

as far as the subjective aspect is concerned: the bandwidth is wide, clear, there is no lack of bottom, and the treble is pleasant, not exaggerated. in my opinion the amplifier sounds great .

Added after 5 [minutes]:

Olkus wrote:

In my opinion this black cage is a bit out of keeping with the silver components of the amp. Nothing else is black so in my opinion it would be better if either the grille was silver or the rest was also black. The white knob doesn't fit very well either, but I suspect it's a temporary solution. And the RCA sockets on the front - not very convincing, I think it would be better if they were on the back, there's plenty of space there.
These black PCBs are some kind of "off-the-shelf" or just ordered?

Thank you for sharing your feelings! I personally like the effect of a kind of colour 'dissonance' in the form of the black cage, and as for the knob, I personally like that too, however your responses are prompting me to see what the other knobs will look like. The RCA sockets are at the front because there are more wires at the back with AC and anode voltages (with high current) so if they were located there, it could affect some interference. But really thanks for the feedback !

Olkus wrote:

These black PCBs are some "off-the-shelf" or just ordered ?

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The PCBs are also of my design, they were ordered from the JLCPCB website. Greetings!

Pltin74 wrote:

Thanks for sharing your feelings! I personally like the effect of a kind of colour "dissonance" in the form of the black cage, and as for the knob, I also personally like it, however your responses make me want to see what other knobs will look like.

If you like it then OK. After all, it is you where this amplifier will stand and play, the most important thing is that you like it .

Pltin74 wrote:

The RCA sockets are at the front because at the back there are more wires with AC and anode voltages (with high current) so if they were placed there, it could affect some interference. But really thanks for the feedback !

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Anode voltages (if constant) are less of a problem than AC. I would just be afraid that the RCA wires at the front will spoil the aesthetics of the amplifier, there will be a preamp, DAC or whatever added after some time and it will make a "noodle" at the front.

Pltin74 wrote:

PCBs are also of my design, they were ordered from the JLCPCB website.

This is also what I suspected However, I personally would not want to order such small PCBs and would make at home, even much larger ones I make at home, comes out cheaper overall.

Regards,
A.

Hello
I disagree with ChatGPT's answers , a total crock.
Reading this text, I feel like I am at an exhibition of paintings where
instead of pictures in frames there are descriptions of them.
Analysing an amplifier without a schematic diagram is like tuning the drive of a car
without an engine.
It is a great pity, because there are few tube designs now and it would be interesting to
to learn about new (or old) solutions of such constructions.
designs.

>>21408196 don't want to publish the schematic as I plan to try and monetise my creations in the future .

GPT sounds a bit like an audiophile with this analysis,
I found another thing that GPT completely fails to do - write code in Bascom 8051

What kind of woodworking is needed for such an effect? Sanding/varnishing/staining?

>>21408387 the wood has been sanded (at the carpenter's) and oiled with wood oil. after oiling nothing else .

Added after 24 [minutes]:

TechEkspert wrote:

cannot-write code in Bascom 8051

coding is better handled by claude, I recommend .

Hello

What are the approximate costs of building such an amplifier and from which devices will this amplifier amplify the audio signal?

Greetings

>>21408573 What costs are involved? About building it yourself or having it built by me? If it's the 2nd, then please priv :d

As for sound sources, I've plugged everything I have into it: phone, computer and turntable - all flawless.

The interior aesthetics are undoubtedly an asset to this project. And I have to admit it, even though I am not a fan of the old style of mounting tube equipment.

On the electronic side, it's hard to say, because we don't know anything. But I perfectly understand my colleague not wanting to reveal his secrets. (I am increasingly thinking the same thing myself.)

As for the impedance of the headphones, it's clear that when you're doing an OTL tube design, you're not going to power low-impedance headphones with it. Although those stated 250 ohms are a bit puzzling. I use my OTL myself to power 50 ohm headphones with no problems.

To be honest, even for a tube headphone amplifier, I find your project quite large. Personally, I would prefer something smaller. I know, everything is a matter of taste. And apparently we do not discuss about taste. But since you have presented your project, let me express my own opinion.
At first glance, visually, the design gives the impression of neat refinement. But when I looked at it a little longer, apart from the aforementioned large dimensions, I could see a lack of style here, as if it were a total misfit. (I don't mean the combination of wood and metal. This, done well, I like very much.) For me, too many colours of wood, aluminium would be enough. And here additionally black of the transformer grille, grey/white volume control knob. On top of that, I would prefer a solid rather than split aluminium insert on the front. Other than that, though, for me, the RCA inputs on the front are a poor idea. They spoil the aesthetics a bit (especially when something is plugged in, rather than standing as in the pictures, unconnected). And while I'm on the subject of sockets, the headphone jack you used isn't one of the prettiest either. Yes I know, it allows for easy mounting in the faceplate, but it also disfigures it a bit.

I am very sorry to have expressed my opinion so strongly. It's not my intention to belittle you or your actions. But since you mentioned your intentions to possibly sell, I simply expressed my opinion from the point of view of a potential customer.

p.s.

Pltin74 wrote:

What about the sound sources, (...) and the turntable - all flawless.

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Except that not every turntable. You don't have an RIAA preamp in this amp, so the connected turntable must have one built in.

250ohm a 50ohm mentioned by kol titka is also OK. Maybe even 32ohm would do. The power will be reduced a little.

As for size..the dedicated designs for the Sennheisers are huge. Too bad you can't see that wonderful classic assembly through the sweeping enclosure. Like 1960s Japan but much more professional and qualitatively better.

tytka wrote:

With regard to headphone impedance, it's clear that when you're doing an OTL tube design, you're not going to power low-impedance headphones with it. Although those stated 250 ohms are a bit puzzling. I myself power 50 ohm headphones with my OTL without any problems.

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The amp was designed to drive 250ohm headphones (which I have) to the maximum. You could plug 50ohm headphones into it, the music would "play", but the power would be drastically reduced (and it would also be unhealthy for the tube, as the operating points would shift etc).

tytka wrote:

I am very sorry to have expressed my opinion so strongly. It is not my intention to belittle you or your actions. But since you mentioned intentions of a possible sale, I simply expressed my opinion from the point of view of a potential customer.

I am very happy for any constructive criticism because it allows me to learn a lot and as you say it allows me to know the opinion of a potential customer, also you have nothing to worry about and apologise! I am a person of the "younger generation" and I and my friends personally like the way it looks, I also know that not everyone has the same taste and not everyone will like it, but I find your opinion valuable and I will probably speak up when I actually design something to sell! The only thing is that I'm actually going to change the volume knob for a different one, because I can see that there's a lot of feedback about how it looks. Thanks!

Added after 3 [minutes]:

>>21411456 §

Tremolo wrote:

250ohm a 50ohm mentioned by kol titka is also OK. Maybe even 32ohm would do. The power will be reduced a little.

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Exactly!

Tremolo wrote:

As for size..these dedicated designs for Sennheisers are huge

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Yes, these are huge (and for me visually uninteresting) amps. Mcintosh also has a relatively large headphone amplifier

Tremolo wrote:

Like Japan from the 1960s but much more professional and qualitatively better.

I never thought anyone would say my work looked more professional than the layout of the iconic Japanese amplifiers for which I sincerely thank you!

Pltin74 wrote:

I never thought anyone would say my work looked more professional than the layout of the iconic Japanese amplifiers

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Well that opinion was probably a bit over the top though. Besides, note that in the 1960s of the previous century, it was even the Japanese who had inferior technical conditions to those to which we currently have access. Also, although many consider the Japanese designs of the time to be a benchmark; with all due respect to them, they were unfortunately not perfect. There were some not entirely well thought-out solutions and design flaws in them. On the other hand, however, with some minor or major problems, they often served their users much longer than their designers had planned.

By the way, I will repeat what I suggested earlier. Your design, which you have presented here, makes a much better impression on me looking inside than when I look at it from the outside. And although the inside is not perfect (one could pick on some things), the fact is that, as a diy project, overall it makes a very good impression of the quality of the aesthetics of the interior workmanship.
Of course, with the exterior aesthetics, it's no tragedy, but in my opinion the potential is there and you still have something to work on in this area.
Of course, I realise that the current state may appeal to many people and in their opinion I am wrong, I am not right.
Well, the truth is that I know perfectly well what I like and what I don't like. I don't have to look for my favourite style, because I know it perfectly well. And I actually pride myself on the fact that I am not at all impressed by, for example, the Tesla Cybertruck.