[viggen]

thanks jon and frm

could I use 3e29 in place of 829b?

[FullRangeMan]

thanks jon and frm

could I use 3e29 in place of 829b?

According Radio Museum you can.
Iam at the phone, later I will post more.
Check what RM say on these tubes:
https://www.radiomuseum.org/tubes/tube_829b.html

[FullRangeMan]

Also check the Russian version GU29, military surplus made by Reflector and Ulyanov factories. GSTubes is out of stock now, but you have to ask Andrey to get some tubes for you, they are dirty cheap.
https://www.gstube.com/catalog/?key=gu29&submit=Find

[viggen]

thanks again frm.  just bought some rca 3e29 off eby

[Jon L]

Also check the Russian version GU29, military surplus made by Reflector and Ulyanov factories. GSTubes is out of stock now, but you have to ask Andrey to get some tubes for you, they are dirty cheap.
https://www.gstube.com/catalog/?key=gu29&submit=Find

GU29 tubes I have found have high shipping fees from Ukraine/Russia, so the total cost ends up being similar/higher compared to RCA 829B.

I must say the 829B tubes are my new favorite tube type, even the stock Chinese(?) 829B tubes and RCA 829B tubes.  After more testing, i definitely prefer 829B over FU19 tubes, even Amperex FU19 tubes I found.  RCA 3e29 tubes look the same(?) as RCA 829B tubes to my eyes. 

I have found the connectors for the tube top pins are a bit too tight for FU19 tubes and bit too loose for FM30/829B tubes, for which the connector pins probably need to be crimped a bit more with pliars. 

[FullRangeMan]

GU29 tubes I have found have high shipping fees from Ukraine/Russia, so the total cost ends up being similar/higher compared to RCA 829B.

I must say the 829B tubes are my new favorite tube type, even the stock Chinese(?) 829B tubes and RCA 829B tubes.  After more testing, i definitely prefer 829B over FU19 tubes, even Amperex FU19 tubes I found.  RCA 3e29 tubes look the same(?) as RCA 829B tubes to my eyes. 

I have found the connectors for the tube top pins are a bit too tight for FU19 tubes and bit too loose for FM30/829B tubes, for which the connector pins probably need to be crimped a bit more with pliars.

High shipping fees from what vendor ?
GSTubes site in Moscow always had low shipping prices similar to China for me. You can solder the transformer wire in the top pins for a better connection.

[Jon L]

High shipping fees from what vendor ?
GSTubes site in Moscow always had low shipping prices similar to China for me. You can solder the transformer wire in the top pins for a better connection.

When I go to the GSTubes site and search for GU29, I get one search result, which if I click on it, I get a photo.  But from there, I cannot figure out how to actually get a price and shipping and order.  Clicking on photo does not go anywhere either..  Very old school website.

[FullRangeMan]

When I go to the GSTubes site and search for GU29, I get one search result, which if I click on it, I get a photo.  But from there, I cannot figure out how to actually get a price and shipping and order.  Clicking on photo does not go anywhere either..  Very old school website.

The price also old school, think of GSTube site as NOS or Vintage.
As I told you before in the post #22 GSTube is out of stock now for the GU29.
You have to email Andrey asking for this tube and he will buy it at Reflector or Ulyanov factories. To get the shipping quote you have to email Andrey at mail at gstube.com as the ship price is calc according the package weight and country destination.

In the GSTube site when the tube is out of stock the tube have no price info and no cart/basket button to Check-out.
When the tube are in stock again the site will show the price at right side and the Cart/basket buttom will appear also. You also can order direct by email with Andrey or his wife Natasha.

Last time I bought at GSTube the Registered shipping price with Tracking Number was under $20 for eight 6C33 tubes.
https://www.gstube.com/catalog/?key=gu29&submit=Find
Phone: +7 (966)666-14.63
Whats App +7 (903)799-22.40
EDITED

[viggen]

Seller didn't realize amp didn't get on a plane for 10 days.  But, after the issue is fixed, it only took 9 days to get to me.

Opened it last night. 

With stock tubes: The good.  Airy.  Gobs of grippy bass.  Clean highs.  The bad.  Vocals in your face.  Sound stage sorta fragmented.

Replaced stock FU19 with RCA 3E29.  The good.  Much smoother and cohesive overall presentation.  Much more subdued compared to FU19.  It's like a completely different amp.  The bass and highs are not as exaggerated and vocals blend in with the rest of the band. 

Replaced stock driver tube with NOS 12ax7 with adapter (original tube off a fisher x100 so should be a Mullard).  The change.  Highs are softer more romantic but at the same time the sound is less dark, more bloom. 

My forever amp sorta just got surpassed by this one:



With a pair of HD58x, it's a very good match with the amp with stock tubes.  The vocals are still too forward but it otherwise the hp is perfectly driven.  However, with stocks tubes replaced, the hp sounds veiled.  I'd say as a hp amp, the "fu19" amp sounds very similar to the APPJ EL84 amp.  It has a very lively presence which is a good match with the 582x which is veiled on its own.

This is only after about 12 hours of ownership.

Side note:

1. Heavy paint smell after opening the box.  Probably wrapped and boxed it up right after the paint dried.  A sign of high demand?  I currently have the windows, doors and ceiling fan open and its cold outside for southern california.
2. Perfectly quiet even on initial turn on.  Even my forever amp has a hint of a buzz for about 5 seconds when initially turned on.  And, it's a 100db+ speaker.

[Jon L]

Yeah, the value is crazy, almost presenting a mental block that an amp this cheap should not sound this great 

[FullRangeMan]

If this nice amp was an Audio Note how much do you think it would cost?
a) $1K
b) $10,000
c) $ 30,000
d) more than $30K

[viggen]

i've only owned the audio note oto.  my forever amp surpasses it.  no comparison. 

the fu19 is marginally better than my forever amp.  funny i think i prefer the forever amp when i am sitting in the listening position.  however, when i am off axis or working at my standing desk, i definitely prefer the fu19.  it doesn't have a sweet spot.  or should i say the sweet spot is every but where it should be. 

so if the oto is $4k msrp, the fu19 should be close to that?  i mean what sets the fu19's price back is that it doesn't have any boutique parts. well, the gaincard with $.29 cents worth of parts sold for $3k in 1990s dollars.

side note.  i asked seller whether i could use 12at7 in place of 12ax7 and he replied no.  in my other amps including the oto, i am able to use 12at7 and 12au7 in place of 12ax7.  so i was hoping i could with this amp too since i much prefer the at and au over the ax in those amps.

[viggen]

speaking of what parts might be in here, i found an el34 amp built by the same maker and the owner has some descriptions of the parts used:

https://hifihaven.org/index.php?threads/this-isnt-about-cheap-asian-sourced-amps-preamps-but-it-is-about-economics-and-value.4569/page-2#post-94668

Based on this, one might want to replace some parts for longer life span and safety?

[FullRangeMan]

i asked seller whether i could use 12at7 in place of 12ax7 and he replied no.  in my other amps including the oto, i am able to use 12at7 and 12au7 in place of 12ax7.  so i was hoping i could with this amp too since i much prefer the at and au over the ax in those amps.

12AX7 have a huge gain of 100 times, maybe the circuit need this gain.
However higher the gain, higher the potential for distortion and hiss.

12AX7    gain=100,
7025       gain 100  Low Noise
12AT7    gain=60/70
ECC81    gain=60
TFK ECC801S   gain=60,  6201, 6679,
12AU7   gain=20,  ECC82, ECC802S, 5963, 5814, 6189, 7316,
12FV7    gain=21

[FullRangeMan]

speaking of what parts might be in here, i found an el34 amp built by the same maker and the owner has some descriptions of the parts used:

https://hifihaven.org/index.php?threads/this-isnt-about-cheap-asian-sourced-amps-preamps-but-it-is-about-economics-and-value.4569/page-2#post-94668

Based on this, one might want to replace some parts for longer life span and safety?

I would replace a part only when it broke.
By the internal photo it use a thin wire, so it will benefit very much of a full wire replacement as Hard Wiring Neotech UPOCC AWG 16 or 18.

[nlitworld]

If you wanted to try something other than 12AX7 in there, try an RCA 5751. Not lower gain enough to feel its lacking, but the dynamics tend to improve greatly over full figured 12AX7.

[SET Man]

Hey!

    I've seen these amps around on eBay before. They look cool for sure, like an old science experiment. How many versions are there?

   Jon L and Viggen... are you guys have the same version? Where did you two got them from? From the same seller?

[opnly bafld]

I would replace a part only when it broke.

After the fire and when it takes other parts with it?

The large brown filter caps are junk and can take more expensive parts with them when they decide to go.
If it's a once in a while amp maybe not a big deal, but if a daily use amp maybe not.

[viggen]

Hey!

    I've seen these amps around on eBay before. They look cool for sure, like an old science experiment. How many versions are there?

   Jon L and Viggen... are you guys have the same version? Where did you two got them from? From the same seller?

The link i bought from has a few other versions.  the one JL and I got are the same with different enclosures.

https://www.aliexpress.us/item/3256805709492361.html?spm=a2g0o.order_list.order_list_main.5.21ef1802jLu98g&gatewayAdapt=glo2usa

[viggen]

i bought a rca 12ax7 radiotron to match the power tubes' aesthetics.

and, thinking about bringing the amp to a tech to replace the no name caps with some nichicons and getting the grounding shored up if they aren't already.  maybe replace the potentiometer.  got some tkd laying around.

here's a schema i found: