Pre-amplifier on a 6zh32p tube

Tube amplifier Nobsound MS-10D

model: MS-10D MKII Bluetooth amplifier
type: 2.0 Stereo
Output Power: 25W + 25W 8Ohm / 45W + 45W 4ohm
power consumption: 100 W
input impedance: 47 kOhm
Input sensitivity: 300mV
signal/noise: 90db
Frequency range: 28 Hz - 20 kHz
output impedance: 4 - 8 ohms
radio tubes: 6N1 x 2 / 6P1 x 2
Audio input: 2 RCA audio input and Bluetooth/USB
output: audio tulips 4 pcs.
weight: 5 kg
size: 31.2 x 27 x 15 cm (L x W x H)
input voltage: 220V-230V 60Hz
support bluetooth music playback: iPhone, apple, smartphones, tablets and other devices
USB music format support: WMA/WMV/MP3/APE/FLAC
price: 90 dollars

About prices

Single-tube low-frequency amplifier (based on a 6p9 tube)

The price indicated is average - I have not yet looked for a cheaper place through this lotion for monitoring goods. The most budget LUNCH model on Aliexpress costs only twenty-five dollars... 25, Karl! True, excluding delivery. Yes, for this money it is difficult to order a normal transformer, but here they offer a ready-made device in a housing, and a very decent housing, unlike many homemade ones:

https://elwo.ru/publ/skhemi_usilitelej/lampovyj_usilitel_na_50_vatt/6-1-0-810
https://el-shema.ru/publ/lampovyj_usilitel_zvuka/1-1-0-118
https://elwo.ru/publ/schemy_usilitelej/lampovyj_usilitel_quotglamurquot/6-1-0-38
https://elwo.ru/publ/skhemia_usilitelej/odnotaktnyj_lampovyj_usilitel_konstrukcija/6-1-0-552
https://elwo.ru/publ/skhema_usilitelej/skhema_lampovogo_usilitelja/6-1-0-622
https://radioskot.ru/publ/unch/prostoj_lampovyj_usilitel/6-1-0-485
https://radioskot.ru/publ/unch/lampovyj_usilitel_moshhnosti/6-1-0-694
https://elwo.ru/publ/schemy_usilitelej/lampovyj_usilitel_dlja_naushnikov/6-1-0-491
https://radioskot.ru/publ/unch/dvukhtaktnyj_lampovyj_usilitel/6-1-0-987
https://elwo.ru/publ/schemy_usilitelej/lampovyj_usilitel_volna/6-1-0-666

In general, my indignation knows no bounds. When they sold various stun guns - I was silent, when Gauss guns appeared on Aliexpress - I just gritted my teeth, but when it became possible to buy a pretty good tube amplifier for 5,000 rubles - I will say: ENOUGH! I've had enough: I'm giving up this thankless task and going to a monastery! These Asians have become adept at making and selling everything, literally everything. And even the candles and icons in the monastery (I suspect) will proudly bear the inscription Made in China... Although wait - someone will have to repair all this radio equipment when the warranty period ends and they start to break down. So we still have work to do. Bye…

Discuss the article CHINESE TUBE AMPLIFIERS

Stereo preamplifier using Chinese 6J1 tubes

Review of a tube preamplifier based on Chinese 6J1 tubes. The purpose of the device is to amplify the signal to a level that is more acceptable for subsequent amplification by final power amplifiers. Preamplifiers are responsible for switching functions, adjusting the signal tone, using them as a headphone amplifier, various effects, etc. The simplest option here is just a tube pre board. Lamps included. Price

This device costs approximately the same on Ali and Ebay, around $10-14

How they sent it

They were simply packed in foam rubber. It's good that the lamps didn't break.

External examination of the patient

Board size - 76 x 74 x 20mm. Three holes for installation in the case on stands - the device does not stand very stable on a flat surface.

Turn on

To turn on the preamp, you need

an AC VOLTAGE of 12 V 1 A. The device will not work under constant voltage. See diagram below. I used a 12V and one and a half amp transformer. Connect directly to the board or via a male power connector with a pin diameter of 5.5*2.5 mm.

Illumination of lamps with LEDs from below has always been a mystery to me. After some time, the lamps will heat up to 45-50 degrees. The large two-watt resistor to the left of the volume control gets very hot. The power switch is combined with the volume control.

Device diagram

I wanted to draw it myself, but someone did it for me on the internet. I checked. matches.

Datasheet for the lamp - Chinese pentode 6J1:

Often Chinese “tube” amplifiers work like this: there is a tube (sometimes even unconnected). Transistors are installed after the lamp, which amplify the sound. Everything is fair here, although the lamps are supplied with an anode voltage of 56 volts. The connection diagram is as follows:

Tests

Before turning it on, I checked the constant voltage at the amplifier output. All OK. Let's check whether the patient amplifies the signal. We connect a Hi-Fi class ULF as an output load.

Let's apply 1 kHz-0.3 Volt to the patient input. Such parameters are usually provided by the headphone output of a cell phone or mp3 player. Let's see with the help of an oscilloscope what the test subject has at the output.

. Input signal is blue (0.32 V), output signal is yellow (1.96 V). As you can see from the picture, the amplifier amplifies the signal and performs the function of a preamplifier. True, the sine wave is inverted relative to the original signal.

The output sinusoid is without distortion, symmetry is maintained. All OK:

Rectangle and triangle - everything is ok:

The output impedance of this board is about 3 kOhm. Accordingly, it cannot be used as a headphone amplifier. In fact, when working with 16-50 Ohm headphones, the amplifier does not enhance the signal, but reduces it. But the bass sounds good. Conclusion: connect this pred only to the ULF.

There are no complaints about the volume control. I didn't notice any distortion of the balance, clicks, or sound at zero volume.

Listening impression

There is no famous “warm” tube sound. The patient rather “softens” the sound. The bass sounds velvety. Some instruments begin to sound more pronounced and interesting. There are no problems with the stereo effect. The channels do not mix into a mess. The stage is ok. The most interesting styles sound like New Age, all sorts of ballads, jazz, classical. I liked how Enigma, Blackmore's Night, Yanni, Vangelis play on the device. For music such as rock or metal, the device does not sound very good due to the above-mentioned “softening” of the sound.

The device has one problem. If you increase the gain above the 0.3 V -> 2 V mode, then a low-frequency hum of 50-100 Hz becomes audible. I tried placing the transformer in the screen and shielding the power wires. The background is not reduced. Possibly due to the power supply and board layout. A high background level is clearly visible on the spectrogram. The signal is not supplied to the amplifier input. Volume control in zero position:

When a signal is given, this background does not go anywhere:

conclusions

An interesting inexpensive lamp device.
The transformer (plug, fuse) for this device costs more than the board. If you drive at a reasonable volume, you won't hear any background hum. We get a pleasant “soft” sound that you can’t make with any digital “improver” or equalizer. And your favorite music will sound more pleasant and with a new shade. Instead of a cat
Do not post this lurka button accordion in the comments.

The product was provided for writing a review by the store. The review was published in accordance with clause 18 of the Site Rules.

Aiqin HIFI EXQUIS EL34 tube amplifier

rectifier: 5Z3P
preamp: 6N9P
power tubes: PSVANE HIFI series EL34-B
Rated output power: ultra-linear 10Wx2, triode 8Wx2, standard connection 12Wx2.
frequency range: 20 Hz - 25 kHz
total power consumption: 115 W
power transformer: 160 W, (96×50)
output transformer: 15W x 2, imported Japanese Z11 0.35mm (66 x 45)
total harmonic distortion: 1% (1 kHz)
input sensitivity: 500 mV - 2000 mV
input impedance: 100K
output impedance: 4, 6, 8 ohms
SNR: 88dB
dimensions (W x H x D): 380 x 160 x 230 mm
Net weight: about 9kg
input voltage: 110 - 240 V 50/60 Hz
price: 155 dollars

Tube amplifier: advantages and disadvantages

Pre-amplifier with a claim to hi-end! (part i)

What are the positive aspects of choosing an integrated amplifier or preamplifier using tubes compared to models that operate on the basis of transistor signal amplification?

The most significant advantages of choosing lamps include the following points:

Relative simplicity of design. The circuitry of such devices is much simpler than that of transistor-type models. All this affects the possibility and cost of equipment repair;
Unique sound due to a number of features and effects. Among these are a significant dynamic range, a high smoothness of the transition to amplitude limitation, a very pleasant overdrive and others;
Significant lamp life (from 10,000 hours) of the device;
High reliability and resistance of the device to short circuits under load;
Non-criticality of equipment to temperature overloads;
Absence of “white noise” (hissing), characteristic of semiconductor equipment models;
Stylish appearance that can successfully and harmoniously complement a wide range of interior styles.

Of course, a tube power amplifier is not the epitome of all advantages. Otherwise, representatives of this technology would completely supplant transistor devices for similar purposes. The weaknesses of the device include:

Considerable weight and dimensions of the device due to the fact that the dimensions of the lamps are much larger than the transistors;
Greater noise level during operation of the device;
The need for time to preheat the tubes before reaching the optimal operating mode of the amplifier;
High output impedance. This factor somewhat limits the range of speaker systems with which specific single-cycle or push-pull tube amplifiers are compatible;
Less linearity compared to semiconductor devices;
High heat generation and power consumption;
Low efficiency (within 10%);
Susceptibility of an amplifier using HF, UHF and microwave lamps to interference.

Without a doubt, based on the number of weaknesses inherent in tube preamps, they cannot be called ideal. But the unique color of the sound that is obtained when using them compensates for all the listed shortcomings.

6Zh32P, EF86

Datasheet

EF86 is good because it has low intrinsic noise, and, accordingly, does not add significant noise to the DC. In addition, the current source on the 86 has a fairly high output impedance and good linearity. Lynx

Well, why only in the driver? The EF86 sounds very good at the input! With it, the two-stroke gets something of the sound of the SE!? JAS

In tape recorders, the EF86 was often biased with a large leakage resistor - 5–10 MΩ. The result was a shift of 0.8 - 1.5 V. dedis

Exactly what “seems to be.” It's ripped off from the EF86. I have an EF86 in my corrector, the socket is soldered into a printed circuit board (breadboard). The board is mounted on the bottom on plastic stands.

I tried to install two 6Zh32P instead of 86s - in both channels). There are two points: 1) the spread of parameters of 32 is so large that I barely had enough adjustment range to set the modes (there is a trimmer there). Moreover, in both channels the lights turned out to be at opposite ends 2) As I said above - the 86s are in panels without shock absorbers, and everything is fine, but with 6Zh32p this number does not work - the microphone effect is SUCH that it should be used in this form at all it is forbidden. Alex Torres

But I poked all sorts of Philips and Telefunken Ef 86 and Russian 6zh32 and did not hear a difference, although I tried very hard. The mode had to be adjusted on that corrector, but the noise was the same, the sound was the same, and the microphone was the same. I tried different ones in different channels and all that I had. True, there is one caveat, all the 6zh32 that I have are no younger than 66, perhaps this is the reason for their goodness compared to new ones. and part of my EF86from the same source as yours, From Mark. Alpi

It is necessary to pay attention to the fact that the EF86 filament is not 6.3 V, but 5.2 V DC. This is similar to the VF14 and Neumann U47 filament supply: reducing the filament reduces the leakage currents of the first grid of the lamp.

Andreas

WHEN I was fooling around with CORRECTORS, the EF86 immediately gave such a sound that I almost stopped loving triodes, but I didn’t listen to my ears and continued to do it on 6s4p. Now I know that Alexander Bokarev was wrong

For example, ef86 - our favorite for its albeit noisy, but delightfully involving sound - has an Er total of about 2.5 MOhm, if we take a quiescent current of about 1.5 mA, the slope will be about 1.3 mA / V, in fact a load of 100 kOhm we will get (with anode about 150 V) a swing of about 100 V, which will correspond to a maximum input of approx. 0.8V amp and 0.55 rms. Even a bad MM head with its 5 mV x 40 = 200 mV fits into this value, and this is at low frequencies. Moreover, 40 cm/s is, as I understand it, a very hypothetical value and with a large margin. Because, in the light of Hunt’s classic works (if I’m not mistaken), there are strong doubts about the possibility of most pickups going around such a groove. HRYUN

On 6Zh32P I made the only “folk” corrector Neophyte. Mode: 120 V anode-cathode, quiescent current 2.9 mA, second grid +140 V. Bias about 1.4 V, it seems. These are practically the maximum operating point modes. Anode load 68 kOhm. wizard

I have an ef86 at the input of the phono preamplifier without any shock absorbers (just don’t hit it with a screwdriver) Alex Torres

I agree with Torres, the 86 lamp does not ring, and even better, the 806 lamp, in general, I thought it was dead until I stood on the grid with my paw... Alexander Bokarev

But as I already said, this does not apply to its “alleged analogue”, 6Zh32P. I tried to put a full paragraph…. Alex Torres