Xduoo Amplifiers
Mar 3, 2022 at 1:13 PM Post #1,126 of 1,430

kibot

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Hello✌
i want to ask you about using mt-603 with S\N 100dB as a buffer between TA 26(with S\N 110dB and DACmagiplus ( with S\N112dB) - does it help with clipping??
Its almoust nice now when i use -11.5dB in APO EQ but i want to try back all WIN and EQ volume to 100%
 
Mar 3, 2022 at 7:24 PM Post #1,127 of 1,430

Ufanco

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Purchased a used Xduoo ta20 from reverb for $250 that included the stock tubes and a pair of Northern electric 12au7tubes.
Seemed a fair price since able to return it and having a limited warranty.
It will be replacing the Loxjie p20 and looking for best tube to be used with low independence iem’s (mest mkII) will be using a Shanling M6 pro 21 as source.
Any suggestion for a good tube for this setup? Anyone using the northern electric tubes and are they any good?
I read thru the thread and thinking the Amperex but seeking other thoughts. Looking to spend around $70 or less.
 
Mar 3, 2022 at 11:44 PM Post #1,128 of 1,430

hmscott

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Purchased a used Xduoo ta20 from reverb for $250 that included the stock tubes and a pair of Northern electric 12au7tubes.
Seemed a fair price since able to return it and having a limited warranty.
It will be replacing the Loxjie p20 and looking for best tube to be used with low independence iem’s (mest mkII) will be using a Shanling M6 pro 21 as source.
Any suggestion for a good tube for this setup? Anyone using the northern electric tubes and are they any good?
I read thru the thread and thinking the Amperex but seeking other thoughts. Looking to spend around $70 or less.
Well, there are lots of nice tubes out there, but you don't need to worry about the IEM impedance, the output gain is handled by SS output, so the tubes don't "touch" the IEM's. That is what makes the TA-20 a great headphone amp, the Hybrid Tube/SS design.

Those Northern Electric 12AU7's aren't cheap @ $47.50 each, and the reviews there look great )
https://www.thetubestore.com/northern-electric-12au7

Northern Electric 12AU7
 
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Mar 4, 2022 at 3:15 PM Post #1,129 of 1,430

Ufanco

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Well, there are lots of nice tubes out there, but you don't need to worry about the IEM impedance, the output gain is handled by SS output, so the tubes don't "touch" the IEM's. That is what makes the TA-20 a great headphone amp, the Hybrid Tube/SS design.

Those Northern Electric 12AU7's aren't cheap @ $47.50 each, and the reviews there look great )
https://www.thetubestore.com/northern-electric-12au7

Northern Electric 12AU7


Thanks maybe it be best to stick with stock and the northern lights tubes for now. Making a list of ones that want to try in future many more options than with Loxjie p20. Any suggestion are welcomed on tubes.
I just received the new 4.4 to xlr cable it sounds much better that the previous one did. It’s the DD ddHiFi DIY-XLR44A and also using the DD ddHiFi XLR44B to connect the 4.4 cables to xlr output. Happy so far with the DD ddHiFi items they seem good quality and don’t break the bank to buy.
 
Mar 4, 2022 at 5:19 PM Post #1,130 of 1,430

YanaMJ

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Purchased a used Xduoo ta20 from reverb for $250 that included the stock tubes and a pair of Northern electric 12au7tubes.
Seemed a fair price since able to return it and having a limited warranty.
It will be replacing the Loxjie p20 and looking for best tube to be used with low independence iem’s (mest mkII) will be using a Shanling M6 pro 21 as source.
Any suggestion for a good tube for this setup? Anyone using the northern electric tubes and are they any good?
I read thru the thread and thinking the Amperex but seeking other thoughts. Looking to spend around $70 or less.
Mini watt
 
Mar 8, 2022 at 9:16 AM Post #1,131 of 1,430

ostewart

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TA-26 with RCA 6AS7G + Sylvania JAN VT-231 (6SN7GT)

PXL_20220307_144319955.jpg
 
Mar 8, 2022 at 12:23 PM Post #1,133 of 1,430

hmscott

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TA-26 with RCA 6AS7G + Sylvania JAN VT-231 (6SN7GT)
Beautiful:wink:
What do you think of the Sylvania with that RCA? I have the same amp with RCA 6AS7G and Tungsol 6SN7GTB but i want to do some tune rolling
Those are both great tube choices! I've wanted to try a "GTB" as the VT-231's are "GT" "original" versions, and the "GTA" and "GTB" have different - higher rating - specifications. I do have a Sylvania "Chrome Top" "Tall Boy" 6SN7GTA and it does sound different than the VT-231's, the "GTB" changes were smaller but I can imagine they sound still different again and I've seen reports they give better tighter Bass than the "GT/VT-231" series.

I've listened to the RCA JAN 6AS7G '50 + Sylvania VT-231, and found that is a great + consistant sounding combination, I have 3 of the VT-231's and they are very consistent in their sound as well - I do make sure to get new testing tubes - 2600/2600 or higher which is the expected readings for New tubes.

I've got 1 of the 1950 RCA JAN 6AS7G in brown box military packaging, and 1 of the Commercial Red box 1961 RCA 6AS7G, and there is a difference in sound between them, but the '50 is 100%/100% new while the '61 is only an estimated 85%/85%, so the difference in sound could be down to hours used.

What I'd found as my best combination so far was a 7236 Cetron (Tung-Sol) + '57 5692 CBS Hytron, both together provided the tightest Bass + Sweet Treble + Smooth Mid's.

That was my favorite combination until I swapped in a Melz '54 6N8S, and that really took the sound stage and clarity of sound to the best level so far, with plenty of tubiness. I tried swapping the '50 RCA JAN 6AS7G with a '61 6H13C Svetlana but the 7236 really kicked up the Bass and complimented both the '54 Melz and '57 5692 Hytron.

From user reports the 7236 is an inexpensive 5998/421A, someday I may try the Tung-Sol (Chatham) 5998 Domino Plate or Westinghouse 421A, but it may be a long hunt as they are both rare and expensive.

My next tube(s) in a few months will likely be the Melz 1578, so I have a back up to that sweet '54 Melz. :)

In these groups I found all I needed to know about which Makes, Models, Years, and details I needed to know to focus in on the best choices at the best price, and I'm sure appreciative of their kind help and assistance:
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-5441008
https://www.head-fi.org/threads/6sn7-tube-addicts.479031/
 
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Mar 8, 2022 at 12:28 PM Post #1,134 of 1,430

ostewart

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Beautiful:wink:
What do you think of the Sylvania with that RCA? I have the same amp with RCA 6AS7G and Tungsol 6SN7GTB but i want to do some tune rolling

I find the RCA to just sit there and do it's job, mine is from around 1960 and is really nice - detailed and smooth, just gets out of the way of the music.

The VT-231 however is quite detailed and crisp, changing from another Sylvania 6SN7GT I have (similar construction to the 6SN7WGT) I noticed a tighter and more controlled sound, especially in the bass. It doesn't have that velvety tube warmth some love, however it is still a natural sounding tube, just one that is cleaner than a lot I have tried.

I got it for really cheap, I don't know how well used it is, but it works perfectly in my amp.
 
Mar 8, 2022 at 12:39 PM Post #1,135 of 1,430

hmscott

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It did seem like the 6AS7G position didn't make much difference - 2 6AS7G and 4 6H13C, until I tried a 7236 variant, then there was a big difference :)

There are a few Sylvania 7236 pairs on eBay right now for $40/tube in pairs - I've successfull negotiated a single tube purchase 4 out of 5 times, it might be worth asking the seller if they have a single 7236 available for sale.

Warning Update: It looks like the Sylvania 7236's aren't actually a "real" 7236, some think they are Sylvania 6080's relabeled as 7236's as they don't sound any different than Sylvania 6080's. I'm going to stick with the Tung-Sol/Cetron 7236's myself.

I paid $59 for my single NOS Cetron 7236:
NOS VINTAGE TUNG SOL CETRON 7236 5998 TUBE WOO HEADAMPS PAIRS AVAILABLE
1646825209689.png
And, over time I've seen that is about the right price - $40-$50/tube in a pair - but also some go for much more - there are a Tung-Sol 7236 and Sylvania 7236 auctions going with $108 as a "buy it now" from the same seller:
https://www.ebay.com/itm/284673358577?hash=item4247dabaf1:g:VisAAOSwuThfyY0e
https://www.ebay.com/itm/284673358504?hash=item4247dabaa8:g:SH0AAOSwPjxfxvRL

I waited until there was a NIB 7236 tube for the right price, and I am very happy I did get mine, it is an amazing sounding upgrade from the 6AS7G - I'll be hunting for another. BTW, I've heard that all of the 7236 tubes were made by Tung-Sol who was later bought by Cetron:
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=7236+tube&_sacat=0

The list of 6AS7G variants in this post was very helpful, with the 7236, 5998, 421A the top compatible variants that reports say make a big difference:
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-5441008

The only 2 steps up would require verifying by Xduoo that the TA-26 could handle the doubled current draw:
6528 - equiv to 5998 but very high gain at 9, twice the current load. Make sure you amp can handle it
6336 - like 6528 but low gain at 2, still twice current load. Make sure you amp can handle it


I've asked Xduoo directly about that question, if those particular tubes can be safely used in the TA-26, but Xduoo haven't tried them and couldn't answer to their specific support in the TA-26. I've thought about getting a couple and sending them to Xduoo with the warnings about what to expect - specification sheets and links to others reports of modifications needed in other amplifiers. But, for now I'm happy with what I've got, and will suggest someone else might want to take up the baton and try this with Xduoo themselves.

Recently I've found reports of use of an even rarer variant, not on the list, and it does sound compatible and promising:
Tung Sol 7802 - https://frank.pocnet.net/sheets/077/7/7802.pdf

The 7208 has been reported to work in amps similar to the TA-26 without modification, and by others with a small mod to avoid self-oscillation due to 20,000 mho of 7208 vs "standard" values of 1/3 (6AS7G)- 1/2 (5998/421A/7236);
https://forum.bottlehead.com/index.php?topic=3664.0

One sold back in December on eBay:
https://www.ebay.com/sch/i.html?_from=R40&_nkw=Tung+Sol+7802&_sacat=0&rt=nc&LH_Sold=1&LH_Complete=1
https://www.ebay.com/itm/324959603962?hash=item4ba91a0cfa:g:YAAAAOSw8mJhxoGv&nma=true&si=RlLfpB3BERKYRO376Ku9L2kwQts%3D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557
Tung-Sol 7208 variant of 6AS7G.JPG

That eBay 7208 product description reminds me that I am also looking for a NIB Bendix 6080WB (also here) with Large Graphite Plates and thick Ceramic Spacers as described here:
"Extremely scarce Tung-Sol 7802WB tube, labeled for Lewis & Kaufman, with original box. This is the only one of these that I've had in decades of tube collecting. Often used in place of the 6AS7 and 6080 in headphone amps. This is the "WB" version, which like its 6080WB counterpart, is made with warp-proof graphite plates, ceramic spacers, heavy glass, and other features that result in a very durable tube. Excellent balance between sections"

Check out the innards of that 7208, the crazy coating on the plates, the triple thick ceramic spacers instead of Mica, the thick copper rods, and the thick glass... one awesome looking tube:
1646762700388.png
Here is a Bendix 6080WB which has similar construction:
https://www.ebay.co.uk/itm/Bendix-Matched-Pair-CEA-6080WB-Tubes-Carbon-Plate-3-Mica-039-s-Excellent-NOS-6080-wb-/304193734092?hash=item46d35c05cc:g:yk4AAOSwJSthcRm9&nma=true&si=vwB3EKVpYaB6f10cNOM9uOs9pWs%3D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557
1646766960475.png

I think I'll buy another 7236, maybe a Tung-Sol labeled to see if they sound different than the Cetron 7236...it really does change the sound of the TA-26, similar as described in that 6AS7G variant list:
7236 - medium gain - great bass, fast and dynamic. Almost SS sounding

The Cetron (Tung-Sol) 7236 adds back a little of the SS sharpness, focus, and adds powerful impact, while giving that wide stage eufonic sound I love. :L3000:

Warning Update:
It looks like the Sylvania 7236's aren't actually a "real" 7236, some think they are Sylvania 6080's relabeled as 7236's as they don't sound any different than Sylvania 6080's. I'm going to stick with the Tung-Sol/Cetron 7236's myself.
 
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Mar 9, 2022 at 5:43 AM Post #1,136 of 1,430

albertmuc

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In the "xDuoo TA-20" I like the "TAD 12AU7A / ECC82" best so far, the sound is clean and detailed, nothing disturbs, on top of that it can be bought new and cheap.

With the "RFT foil getter" I got the feeling of an annoying freshness, but have to switch back to it to verify it. While the "Gold Lion 12AU7 / ECC82 Genalex" sounds too harmonically-soft and not sufficiently clean.
 
Mar 9, 2022 at 5:47 AM Post #1,137 of 1,430

YanaMJ

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With my TA-20, I've tried JJ gold, Sylvania green label of the 50's, TAD, Brimar Uk and Philips Miniwatt Heerlen code delta.

I prefer the Philips without any comparison.
 
Mar 9, 2022 at 6:06 AM Post #1,138 of 1,430

hmscott

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In the "xDuoo TA-20" I like the "TAD 12AU7A / ECC82" best so far, the sound is clean and detailed, nothing disturbs, on top of that it can be bought new and cheap.

With the "RFT foil getter" I got the feeling of an annoying freshness, but have to switch back to it to verify it. While the "Gold Lion 12AU7 / ECC82 Genalex" sounds too harmonically-soft and not sufficiently clean.
I've heard others enjoy the TAD tubes as well :)

And, I've had the same experience with the modern expressions of famous NOS tubes. The Genalex was an ok tube, none of them were offensive, just not verying exciting - they didn't stir my emotions. Same went the Harmonix, modern Mullard, modern Telefunken, JJ, etc.

TAD also has a few other interesting tubes that might be worth trying, I've wanted to try another 12AX7 - the 7025, and my favorite for the TA-20 - a 12AT7:

7025 WA TAD HIGHGRADE Premium Selected
https://www.tubeampdoctor.com/7025-wa-tad-highgrade-premium-selected

12AT7 / ECC81 TAD Premium Selected (symmetrisch/balanced)
https://www.tubeampdoctor.com/12at7/ecc81-tad-premium-selected-symmetrisch/balanced

And, TAD has a 6SN7 too at a good price:

6SN7GT TAD Premium Selected
https://www.tubeampdoctor.com/6sn7gt-tad-premium-selected

I wonder what the original source was for these TAD tubes? NOS TAD tubes - the comments go back a ways...and TAD have good prices on other brands too :)
With my TA-20, I've tried JJ gold, Sylvania green label of the 50's, TAD, Brimar Uk and Philips Miniwatt Heerlen code delta.

I prefer the Philips without any comparison.
I found similarly, the best were Amperex Philips Heerlen Holland E180CC Pinched Waist tubes, unfortunately they were microphonic, which wasn't so bad - I was able to work around it, but then they developed a static noise that would hit randomly. I've sent them back to get another pair reselected, I hope he can find a pair that don't exhibit that noise, as they were the best sounding tubes for me in the TA-20:

NOS NIB PHILIPS HOLLAND PINCHED WAIST D FOIL GETTER E180CC 7062 12AT7 E81CC
1646824190772.png

Fortunately I have a matched pair, plus 3 spares, of these Mullards made in Heerlen Holland, which are a close 2nd:

Matched Pair E180CC NOS Mullard Holland Valve Tubes
1646824362923.png
Unmatched they are a good bit cheaper: E180CC 5965 12AV7 NOS Mullard Holland Valve Tubes

The Heerlen Holland factory made tubes have all been great sounding tubes :)
 
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Mar 9, 2022 at 6:30 AM Post #1,139 of 1,430

ProAcTivo

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Thak you all for the replies. Apreciated.
The CBS must be awesome but is quite expensive... maybe i will go the Melz route as it is more afordable..
To be honest, i dont want to enter the spiral of tuberolling.. about one year ago i start to mess with EQ with my HD600 and since then i found that the most differences i was able to achieve was via EQ.
The addition os the TA-26 was the cherry on top. The sound i already had with EQ needed more power and more bass and sub bass (via eq was not possible to get more without messing up the sound) and the TA-26 gives exactly that. Im very sensitive with high frequencies so the sound is perfect now in that regard. But i do miss some more clarity in the mids(just a hint more) so maybe one of those tubes will bring me that 😉
 
Mar 9, 2022 at 6:41 AM Post #1,140 of 1,430

albertmuc

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