"Say Hello! to my new little friend"

[ginetto61]

Hi @ginetto61,
see post #686 - there I mention : "I've upgraded the main supply caps to Nichicon 250V. The transformer has been upgraded to an R-Core 230v (also found on AExprss) which is 230v AC to 170v AC (x2) & 6.3V AC (x2)".
I doubt gain is 30x, although my board is a bit different to yours (see rectifier issue as discussed in the thread). My volume setting is at 2'o Clock and direct into my Sansui solid state amp. In front of this unit is the TUBE-03.

Hi ! thank you so much for your kind reply and valuable advice. If i understand well you have this Guanzo preamp driving the power amp section of the Sansui ? looking at the schematic i am afraid that the Zout of the Guanzo is quite high. I do not have data anyway Other design topic i do not like is the volume at the output. I will stay on the Tube 01 for now. I have just received a pair of wonderful Mullard to try out

I don't think my board is same as yours as mine doesnt have the rectifier issue as referenced with your type of board (check version on your board). To find out more about the rectifier issue, read the whole thread - is only 36 or so pages.
I recommend looking at the reviews of your board (or a close variant thereof) here: https://www.amazon.com/SainSmart-Assembled-6N3-Headphone-Transformer/product-reviews/B008BGLN5G - and more specifically this one which inspired me to modify my own version: https://www.amazon.com/gp/customer-...f=cm_cr_arp_d_rvw_ttl?ie=UTF8&ASIN=B008BGLN5G

i see on the board the marking XY HI-FI Version: 2.2
The diodes bridge on the low volatge is a chunky KBL410. The one on the high voltage a DB107
i like the Guanzo board sms resistors aside. It looks well laid-out.

The R-Core transformer upgrade was necessary as the power supply in New Zealand is 230/240V and all power worldwide is generally a little higher at the outlet than described - check your own outlet and you'll see it possibly fluctuate to above 220V.
Manufacturers leave a 20% maximum safe tollerance above or below the stated operating voltage to allow for supply fluctuations.
As mine is at 230/240v (actually at 236v - 245v, sometimes over 250v) that will already be pushing the limit, which is why devices bought from Aliexpress/China made for 220V is a bit on the low side for me. Over here, in the rural north of New Zealand, power supply is not as regulated as the power supplied in the cities like Auckland or Wellington (closer to 230V).
I hope this information somehow helps

Yes ! it helps a lot and thank you very much for this. I think i will pass on this unit. But not with the tube project I like so much what these little units gives to the sound. And with many different amps.
And i am now pretty sure that my final tube stage will be a unity gain buffer. I have always to fight with too high gain and too low Zout from the tube units. A buffer will solve both problems.
Thank you so much again.
P.S. By the way i have a curiosity. Differently from other english speaking Countries the NZ accent is very british, very respectful of the standard/Received Pronunciation Differently from Australia for instance Why ? does it depend on the education system applied in NZ maybe?

 

[NZVinylFan]

P.S. By the way i have a curiosity. Differently from other english speaking Countries the NZ accent is very british, very respectful of the standard/Received Pronunciation Differently from Australia for instance Why ? does it depend on the education system applied in NZ maybe?

That's easy to answer. Australia is very far from New Zealand geographically.
Historically, New Zealand had imigrants mostly direct from Britain. As New Zealand is pretty much isolated, it has developed its own unique accent and colloquial sayings.

Australia originated as a British penal (prison) colony and also migrants who went there for their gold rush etc. Australia is far larger and many migrants from all countries, as well as Americans (Allied troops -during WW2) all added to Australia's concious decision to speak in a different way (yes, they wanted to be different deliberately) - there is sufficient historical evidence on this.

My brother-in-law's family are from the Friuli region in Italy and I've been told that their accent or dialect is quite different from someone who is from Central or Southern Italy. So it goes to show, even within a single country there are differences.

http://www.differencebetween.net/la...en-new-zealand-accent-and-australian-accents/

 

[ginetto61]

That's easy to answer. Australia is very far from New Zealand geographically.
Historically, New Zealand had imigrants mostly direct from Britain. As New Zealand is pretty much isolated, it has developed its own unique accent and colloquial sayings...

Thanks for the very interesting explanation. I understand that the family and the school mean a lot as well. Personally, I like the English of theater actors very much. Very clear, charming and musical.

 

[AfterThought]

Does anyone know if it's possible to run this as an actual Unity gain buffer? or is there a massive amount of gain on it?

 

[Masterdraco]

These have a 1:1 unity gain. I bought two as a tube buffer i disconnected the green leds to see the 6n3 tubes glow.

 

[AfterThought]

These have a 1:1 unity gain. I bought two as a tube buffer i disconnected the green leds to see the 6n3 tubes glow.

Nice, so at full "volume" it's 1:1? I kept reading everything from "4x magnification" to 30db gain... And everything in-between.

So the pot is better referred to as an attenuator than a volume knob...?

 

[Masterdraco]

These are tube buffers not preamplifiers mine are 1:1 at full volume. they do give a nice a nice tube like sound though. correct more like volume attenuator.

 

[ginetto61]

These are tube buffers not preamplifiers mine are 1:1 at full volume.
they do give a nice a nice tube like sound though. correct more like volume attenuator

Hi ! could you provide please a link to your exact product ? are you using it with a solid state power amp ?
have you changed tubes ? thanks a lot, gino

 

[AfterThought]

Hi ! could you provide please a link to your exact product ? are you using it with a solid state power amp ?
have you changed tubes ? thanks a lot, gino

I hope it's ok to post this link, but I bought mine from here...

I have a question to the group...

Is it ok to try using 6sn7 (and variants), or 6dj8/6922 (and variant) tubes by using an adapting socket? or is this circuit specifically only good for the 6n3 (and variants)?

 

[ginetto61]

I hope it's ok to post this link, but I bought mine from here... ..

Hi ! thanks It looks like mine
When i flipped the board i realized there is no room for mods ... all resistors are smd I can understand in a dac ... or in a phono But in a line preamp ...
Those 200V rated caps look unfit for the purpose ... 170VACx1,4 = 238V ... i would replace them even before connecting it Better to be safe than sorry I cannot immagine a cap charged with high voltage exploding

 

[AfterThought]

Ok, just a follow up for my previous question a few posts above.

This unit definitely has gain. It’s most certainly not 1:1. @1 KHz there’s roughly 4x amplification of the signal (3.6x more precisely).

I fed the unit using my LG V30 phone to do the test.

I’ve attached the ‘scope screenshot for reference. If you’d like, I can test any other way.

 

[ginetto61]

Ok, just a follow up for my previous question a few posts above. This unit definitely has gain. It’s most certainly not 1:1. @1 KHz there’s roughly 4x amplification of the signal (3.6x more precisely). I fed the unit using my LG V30 phone to do the test. I’ve attached the ‘scope screenshot for reference. If you’d like, I can test any other way.

Hi ! thank you very much indeed for the very helpful information. Honestly i have not connected it yet ... because in mine the main caps are 200V units and 170VAC rectified will be quite above that ... around 240VDC So i should change the caps first
Main other concerns are Vgain and impedance out as i am using solid state power amps with Zin as low as 10kohm Actually this issue of high Zout is becoming a show stopper.
I am thinking more to a basic cathode follower buffer with no gain and much lower Zout I am confused ... i like the sound but there is something missing ... like dynamics and freq extension at the extremes

 

[Poultrygeist]

Adaptors for the 6n3 are not needed as the 2C51 fits and is a great substitute.

 

[Poultrygeist]

Those are not very easy to find in Europe. Some possible replacements I can get are the Russian 6N3P (I, E and DR), Tesla 6CC42 and some 5670.

The adapter subject is just because I was curious and wondering about the possibility of using some 6N23P, or some Tesla E88CC, given their positive reviews on some forums.

I've just ordered one of this 6N3 preamps, lets see and listen how it behaves:

https://a.aliexpress.com/_mPDKsSR

The Russian military grade is a good choice.

 

[drjohnnyfeva]

Those are not very easy to find in Europe. Some possible replacements I can get are the Russian 6N3P (I, E and DR), Tesla 6CC42 and some 5670.

The adapter subject is just because I was curious and wondering about the possibility of using some 6N23P, or some Tesla E88CC, given their positive reviews on some forums.

I've just ordered one of this 6N3 preamps, lets see and listen how it behaves:

https://a.aliexpress.com/_mPDKsSR

I just saw these after ordering a FX Tube06 from Amazon. I'd be interested to know your results on the little unit you bought. I'm sort of up in the air with the 06. I got it simply to put a different tube family in the line. The 06 also uses the 6N3 and the others you mentioned. I ordered a couple RCA 5670's that should arrive this week. How I like those will likely be the determining in keeping the unit or sending it back. Just curious about your unit, carrots99. I don't need tone controls on the 06 and would like to eliminate them perhaps with the use of the one you bought.

 

[Schmidlapper]

Having read through this entire thread I hope owners of this preamp who read it understand that poster Natger offered several worthwhile circuit modifications, the rest not so much. The whole first half of this thread is both sadly humorous and mostly incorrect, with arguments over how to best undo the “dangerous” heater circuit, and the ubiquitous call for bigger coupling caps. The heater circuit isn’t made wrong, it is elevated on the B+, purposely. If you followed the frantic advice and decoupled them, then you were duped.

Are there flaws with the circuit? Sure there are, and poster Natger bundles them all up with several excellent suggestions to actually improve upon them.

Here are a couple direct links to the cream.

https://www.audiokarma.org/forums/i...ew-little-friend.306203/page-33#post-10123357

https://www.audiokarma.org/forums/i...ew-little-friend.306203/page-34#post-10389124

 

[veejoe]

A few observations after almost 9 years of use :
- Guanzo still going strong.
- blocking out the tacky green leds (I used socket savers) made a huge difference : this looks so much cooler!
- using this little pre-amp in the tape loop I honestly can't hear any difference with/without it (using the tape monitor switch). Using it as actual pre-amp (with the Technics pre-amp only as source selector) is the way to go.
- as others have remarked, there is a channel imbalance at very low volume; nothing major though, we're talking really low -less than listening- volume (to most people I suspect!).
- good sound with the russian tubes, Sylvania's and Tesla's.
- contrary to many other users I can't say I find tubes to smooth out less than perfect recordings; if anything they seem to amplify the difference in sound quality between sources : crappy recordings tend to sound really bad, while very good sounding stuff tends to sound even better.

 

[Mdpaudio]

The 6n23p-ev are great sounding tubes. Don’t use any tube with the I suffix as they are designed for better impulse response and sound hard in my trials.

 

[drjohnnyfeva]

A few observations after almost 9 years of use :
- Guanzo still going strong.
- blocking out the tacky green leds (I used socket savers) made a huge difference : this looks so much cooler!
- using this little pre-amp in the tape loop I honestly can't hear any difference with/without it (using the tape monitor switch). Using it as actual pre-amp (with the Technics pre-amp only as source selector) is the way to go.
- as others have remarked, there is a channel imbalance at very low volume; nothing major though, we're talking really low -less than listening- volume (to most people I suspect!).
- good sound with the russian tubes, Sylvania's and Tesla's.
- contrary to many other users I can't say I find tubes to smooth out less than perfect recordings; if anything they seem to amplify the difference in sound quality between sources : crappy recordings tend to sound really bad, while very good sounding stuff tends to sound even better.

Other than the tube savers, have you made any internal changes? And, specifically, what tubes are you using? Numbers and manufacturer, please. This is just for empirical evidence of what works. After 9 years, that's potentially a bonanza of info.

Many thanks in advance!

 

[veejoe]

No internal changes whatsoever. Sorry, I don't have any specific info about the tubes; they were all bought through Ebay, mostly without boxes and at best only fragmentary -if any- printing left on the tubes (hardly any info by the seller too). Honestly, back then I just bought some cheap tubes to try and find out how they would change the sound. Personally, I have never been interested in the purely technical side of the matter, nor do I consider myself an audiophile, just a music lover who happens to like the 'tube sound' (assuming there is such a thing - which lots of other people question anyway, for that matter). You'll find that other posters in this thread have offered a wealth of technical information and user experiences with different tubes.