Author Topic: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)  (Read 11467 times)

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Offline estaana

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #60 on: Oct 06, 2018 at 03:09 AM »
What is the sensitivity of your speakers ?

rated 93db  ... the other pair rated at 96db

Offline qguy

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #61 on: Oct 07, 2018 at 11:23 AM »
That should work...

The only question left is will it sound good on the 2 watt tube amp

rated 93db  ... the other pair rated at 96db

Offline tony

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how do we defend our freedom? by the truth when it is assaulted by Marcos lies....

Offline tetablanco

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #63 on: Nov 01, 2019 at 12:45 PM »
After getting NOS GE 5654W tubes, I strongly suggest that you upgrade the op amps too. A pair of LM4562 work very nicely after the required burn in and a couple of weeks of use. Have a couple of other op amps on the way too (MUSES 8920 and SX52). I'm using a KGUSS T3 BILE 6J1 preamp which I got for P1650.

Offline RXV

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #64 on: Nov 01, 2019 at 12:53 PM »
Hi sir Teta,

Very interesting upgrade there. Do you think it (OP amp) will also work/fit with the original poster's item (FX Audio Tube-01)?
And where do you source the said OP amps?

Thanks!
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Offline tony

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #65 on: Nov 01, 2019 at 04:03 PM »
i have those opamps in my bin, but for the particular 6J1 featured here, no amp amps were used....btw, i also have the western electric 403 tube equivalent of the 6j1/5654 pentodes....
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Offline tetablanco

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #66 on: Nov 08, 2019 at 11:23 PM »
Hi sir Teta,

Very interesting upgrade there. Do you think it (OP amp) will also work/fit with the original poster's item (FX Audio Tube-01)?
And where do you source the said OP amps?

Thanks!

I chose the Kguss T3 Nike 6j1 preamp since the internal components seem to be of good quality. I get my op amps from Lazada, Shopee, or Ebay. So far, my best sounding op amps are a dual modded OPA627AU (Audio Jade version) and the LM4562. I have a Muses 8920 on the way too.

Offline tony

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« Last Edit: Nov 09, 2019 at 11:30 AM by tony »
how do we defend our freedom? by the truth when it is assaulted by Marcos lies....

Offline fishda

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #68 on: May 26, 2020 at 03:59 PM »
Where to get upgrade tubes for these? I'll purchase one soon.

Offline tony

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #69 on: May 27, 2020 at 07:42 AM »
Where to get upgrade tubes for these? I'll purchase one soon.

western electric version of the 6ak5...https://www.thetubestore.com/western-electric-403-a
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Offline fishda

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #70 on: Mar 20, 2021 at 07:09 PM »
Thanks sir Tony.

Help please.i've replaced my opamps to opa2134 and tubes to ge5654. After the changes the volume output significantly reduced.it's like 50% of the previous output. I've returned the original opamps and tubes suspecting that the new opamps and tubes were the culprit but it's still the same.

What to do now?😁
« Last Edit: Mar 20, 2021 at 10:47 PM by fishda »

Offline tony

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #71 on: Mar 21, 2021 at 08:29 AM »
please post pictures, what preamp is that?, the 6j1 did not use op amp afaik...what psu are you using? it should be 12vac at least...
how do we defend our freedom? by the truth when it is assaulted by Marcos lies....

Offline fishda

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #72 on: Mar 21, 2021 at 08:01 PM »
please post pictures, what preamp is that?, the 6j1 did not use op amp afaik...what psu are you using? it should be 12vac at least...

The fxaudio tube03 sir. i'm using the stock power supply.12v

Offline tony

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #73 on: Mar 21, 2021 at 08:30 PM »
ah, that one with the tone control, so that was what the opamps were for....have your unit checked by markrenz our resident repair tech......
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Offline fishda

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #74 on: Apr 06, 2021 at 08:22 PM »
this amp can be hacked for lower gains....if desired...just two resistors in parallel with the plate load resistors.....R15/R20, just solder in 4.7k metal film resistors to the existing ones, or replace them with 2.7k resistors lowers the gain of this line amp..





Can i remove some resistors to increase the gain?😁

Offline tony

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #75 on: Apr 07, 2021 at 09:30 AM »
Can i remove some resistors to increase the gain?😁

if you increase the gain, you get more distortion, is this what you want? reducing the plate load resistor decreased gain but increased bandwidth and lowered output impedance...
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Offline tony

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #76 on: Apr 07, 2021 at 09:31 AM »
btw, i have about 10 pairs, 5654's and hitachi 6ak5, the 5654 is 1000 per pair and the hitachi's are 1500 a pair....
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Offline qguy

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #77 on: Apr 15, 2021 at 04:42 AM »
Can convert this into a head phone amp for small in ear headphones  by connecting a female headphone jack inputs  into the RCA outputs ?

headphones specs
Sensitivity: 112dB
Impedance: 25Ω
« Last Edit: Apr 15, 2021 at 04:47 AM by qguy »

Offline tony

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #78 on: Apr 15, 2021 at 09:23 AM »
^i doubt it, high output impedance unless you are using earphones with greater than 2k ohm, perhaps a matching transformer will work better...
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Offline juneaki

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #79 on: Jul 14, 2021 at 12:03 PM »
My FX Audio Mini 6j1 tube preamp is now two year old. Lately i noticed popping sound is outputted by the preamp to the amplifier, ano po kaya ang dahilan?

Offline tony

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #80 on: Jul 15, 2021 at 07:43 AM »
ecaps drying out can be culprit...
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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #81 on: Jul 15, 2021 at 10:16 AM »
ecaps drying out can be culprit...

Thanks sir Tony. Time to visit a friend.

Offline estaana

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #82 on: Jul 15, 2021 at 10:57 AM »
My FX Audio Mini 6j1 tube preamp is now two year old. Lately i noticed popping sound is outputted by the preamp to the amplifier, ano po kaya ang dahilan?
  na try mo na ba i-pull out the tubes and re insert baka me maluwag lang o dumi sa fitment between tube pins and tube socket

Offline tony

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #83 on: Jul 17, 2021 at 08:14 PM »
  na try mo na ba i-pull out the tubes and re insert baka me maluwag lang o dumi sa fitment between tube pins and tube socket

yes, this can also be a cause china sockets gets tarnished more easily, kahit pa ceramic sya, yung metal na ginamit parang metal ng maling...... :D
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Offline CMac

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #84 on: Jul 18, 2021 at 02:02 PM »
agree with tony about the caps but 2 years is a not really a long time imo so i think potentiometer/vol knob might also need replacing

Offline tony

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #85 on: Jul 19, 2021 at 08:15 AM »
agree with tony about the caps but 2 years is a not really a long time imo so i think potentiometer/vol knob might also need replacing

onsidering the quality of china goods, that is not surprising...
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Offline CMac

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #86 on: Jul 19, 2021 at 12:04 PM »
onsidering the quality of china goods, that is not surprising...

Actually had to rethink after posting, Chongx comes to mind. lol

Offline estaana

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Re: Audio Mini 6J1 Valve & Vacuum Tube Pre-Amplifier(@lazada)
« Reply #87 on: Feb 06, 2023 at 10:07 PM »
buhayin natin ang thread na to...      i bought a Miniwatt 2013 SET tube amplifier 3 watts per channel, bought from Shoppee many months ago... after completing the burn in process of 100 hours (as per recommendation)  - ayun nag open up na nga ang tunog!.... pero nakulangan ako sa bass.... so I tried to source an equally inexpensive NFX Audio preamp (with bass & treble controls)... these I then connected to my hi efficiency fullrange single driver speakers (either fostex or diatone).... boom! full bodied sound! i can't believe 3 watts is powerful enough for my room setup/needs. ganda talaga tube sound! paired with mentioned speakers.  sila talaga magka match....  in my experience di na kelangan to shell out large amount of money to enjoy music thru tubes ;D