[mordy]

drats, couldn't find the album on Tidal

/sad

I found the album on YouTube but just type in Wood after the name (not Wood II)

 

[L0rdGwyn]

Hello Peeps...

Been a warm summer, been busy with lots of outdoor projects. Fired up the GOTL this evening, to make sure it still works

And happily, it does.

Using the simple tube set of an NOS Visseaux 6N7GT driver and a pair of Mullard 6080's as powers....HOW SWEET IT IS!!!

If we have any Acoustic Bass aficionado's reading, may I suggest:



Artist: Brian Bromberg
Album: Wood II

Listen carefully, kids, and all your hopes and dreams might just come true


Cheers....

.

drats, couldn't find the album on Tidal

/sad

I found the album on YouTube but just type in Wood after the name (not Wood II)

It's on Spotify!



Listening now, Visseaux 6J5G, Cetron 6336B and the Auteur, good stuff @JazzVinyl

The vibrato he generates on these complex passages is impressive, the callsuses on this guys fingers could probably deflect bullets.

 

[UntilThen]

Momentarily changing the topic... Picked up a somewhat rare 5U4G. This one was manufactured by Ferranti, which was a British electronics company that operated for over a century, from 1885 until it went bankrupt in 1993.

Again, per Glenn, this can be used in the OTL with four or six 6BL7 / 6BX7, but it is not powerful enough to use with 6AS7-type output tubes. And of course, it is perfectly suitable for use in the GEL3N.

I am pleased to report that it lights up but haven't had a chance to audition it. Later this evening I hope....

Ken, how about the GEC U52? I can pick up this locally for $400 aussie dollars. Pins are tight so are the base. Tested very good. Potentially for use in the GEL3N. Worth it?

 

[L0rdGwyn]

Not sure if there was any interest in these tubes when I posted them before, but I have done some A-Bing of the Visseaux 6J5G (shouldered) and 6J5MG (metal can). I have the day off, so I will providing some thread filler for your viewing pleasure (or displeasure)

Internals are identical per this post: https://www.head-fi.org/threads/feliks-audio-elise-impressions-thread-–-a-new-start-please-read-first-post-for-summary.813488/page-214#post-12970528

Going back and forth, I would say the shouldered pair may have a 5-10% advantage over the metal can in staging and body, but it is a very small difference. At around 2x the price for the shouldered, it is probably a small enough difference that the metal can version would satisfy. They are both uncommon, but the metal cans seem to pop up more on eBay and at international shops.

These are both excellent drivers though, I would take them over some of the very best 6SN7s.

Still listening to JazzVinyl's bassist, love the opening rendition of Caravan and the Shining Star cover trio.

 

[gibosi]

Ken, how about the GEC U52? I can pick up this locally for $400 aussie dollars. Pins are tight so are the base. Tested very good. Potentially for use in the GEL3N. Worth it?

"Worth it' is a difficult question to answer since the way each of us perceives sound is so subjective. But GEC rectifiers are among my favorites and many others have written glowing reviews of the U52, so I would say it is worth getting if the price is right.

400 Australian dollars is equal to about 271 US dollars. Checking eBay's sold listings for the last 30 days, this tube has sold for as little as US$173 to as much as US$458, but most have sold for around US$265. Assuming that the cost to ship within Australia is cheap, I would say that the one you found is worth it.

 

[leftside]

One of the headphones I'd like to drive are a planar @29 ohms and the other a somewhat power hungry new driver type @ 38ohms.

Should be able to drive most headphones well. It's using 3 Lundahl transformers. Chat with Glenn about the most suitable output impedance of the transformers for your headphones. I'm getting a very specific build, as a I already have "The Beast" (aka Glenn 300B) and I'm also getting a custom OTL amp built by a builder here in Canada.

 

[UntilThen]

"Worth it' is a difficult question to answer since the way each of us perceives sound is so subjective. But GEC rectifiers are among my favorites and many others have written glowing reviews of the U52, so I would say it is worth getting if the price is right.

400 Australian dollars is equal to about 271 US dollars. Checking eBay's sold listings for the last 30 days, this tube has sold for as little as US$173 to as much as US$458, but most have sold for around US$265. Assuming that the cost to ship within Australia is cheap, I would say that the one you found is worth it.

Brilliant. You're better than my financial adviser. Shares were wiped out by almost 90 billions in the last 2 days so the consolation is to buy one nice tube.

Yes, locally the postage plus insurance for the cost of the tube is only $16.90.

 

[UntilThen]

Deyan completed my adapters. Very nice ! Also bought 2 GEC L63 from Langrex to try out.

 

[Xcalibur255]

The 300B amp doesn't work so well with the Stellia though. The Stellia are too sensitive and noise is generated. The 300B is dead silent with the LCD4 (and 3) though.

If your company wants to move to the Cloud, I might be able to help, but I admit hardware electronics is not my day job. I've been trying to read what I can about matching amps to headphones and found this article useful:
https://www.headphonesty.com/2019/04/headphone-impedance-demystified/

"The term ‘rule of eighths’ is used as a rough guide. Divide the headphone impedance by 8, and that is the maximum source output impedance (32 ohm headphones / 8 = 4 ohm maximum source output impedance). In practice, it isn’t that strict a rule and often success can be had with a greater range."

The rule of eighths is really for SS amplifiers. With tubes you want the impedance to match closely otherwise you don't get power transfer. On SS the relationship between load and source impedance is different and power transfer is not inhibited by the mismatch the way it is with tubes, so the focus there is on getting a good damping factor to prevent unexpected changes in frequency response.

If you have a 32 ohm headphone and your output transformer has a 32 ohm tap then you are all set. This is why some commerical tube amps have a low and high impedance switch and use multi-tap OPTs, otherwise the high-Z headphones like the HD800 might not sound good on the amp.

I can tell you my 600 ohm DT880s sound really bad on the 45 amp, which has a 16 ohm output impedance. If the amp were SS it would not be an issue.

 

[L0rdGwyn]

Another comparison I had hoped to make, the RFT 6SN7 to the RFT 6J5, a sort of direct 6SN7 to 6J5 comparison. Output tubes have changed to Western Eletric 421A.

First, relative to the Visseaux 6J5G, the RFT 6J5 has a drier tone, a little brighter, less lush, but still musical and satisfying. I think they are comparable when it comes to staging, resolve, dynamics.

Going from the RFT 6SN7 to the 6J5, there is a noticeable increase in soundstage and a bit more resolve. The 6SN7 has a little more mid-bass energy compared to the 6J5, but otherwise they sound very similar tonally. Hard to say which I prefer, probably the 6J5. I do like the small increase in warmth 6SN7 adds, but it may be worth losing for better technicalities.

I have a third RFT 6J5 that is lower testing, haven't used it yet. If it were to cause a channel imbalance, I might do some tube surgery to see if they maintain the same welded plates and ceramic spacers of the 6SN7. As @mordy says, for science!

 

[mordy]

No no no.....
Old tubes are precious non-renewable resources. Only smash it if it is totally unusable!

 

[L0rdGwyn]

No no no.....
Old tubes are precious non-renewable resources. Only smash it if it is totally unusable!

It does have a minor imbalance, but no issues otherwise, I might not have to get the hammer.

 

[leftside]

The rule of eighths is really for SS amplifiers. With tubes you want the impedance to match closely otherwise you don't get power transfer. On SS the relationship between load and source impedance is different and power transfer is not inhibited by the mismatch the way it is with tubes, so the focus there is on getting a good damping factor to prevent unexpected changes in frequency response.

If you have a 32 ohm headphone and your output transformer has a 32 ohm tap then you are all set. This is why some commerical tube amps have a low and high impedance switch and use multi-tap OPTs, otherwise the high-Z headphones like the HD800 might not sound good on the amp.

I can tell you my 600 ohm DT880s sound really bad on the 45 amp, which has a 16 ohm output impedance. If the amp were SS it would not be an issue.

Thanks for the additional info. The article I referenced at https://www.headphonesty.com/2019/04/headphone-impedance-demystified/ does also talk about tube amps:
"The load impedance of a pair of headphones also plays an important, and closely related, role in an amplifier’s distortion performance. The operating voltage and current (or bias) chosen for transistors or tubes in amplifiers is optimized by the designer for low impedance loads, high impedance loads, or a compromise of the two."

but did also state "Lots of opinions fly around, often contradictory".

At the end of the day, I'm going to let the expert decide (i.e. Glenn) and if Glenn also says the output transformer should have a 32 ohm tap, then I'm going to go with that. Asking these questions has helped with my learning, so thanks again for the additional info.

 

[L0rdGwyn]

What?! I thought one of my MOV L63 was broken, made barely a sound in my old amp, every other 6J5 I had worked flawlessly with the adapter. Threw them in the GOTL in case there was some magic revival sauce in Glenn's amp...

THEY LIVE!!! No idea what happened, awesome. Jamming to Yves Tumor - Safe In The Hands of Love, killer album for those that like experimental electronic music.

Yeah, these things sound good...

 

[Xcalibur255]

Thanks for the additional info. The article I referenced at https://www.headphonesty.com/2019/04/headphone-impedance-demystified/ does also talk about tube amps:
"The load impedance of a pair of headphones also plays an important, and closely related, role in an amplifier’s distortion performance. The operating voltage and current (or bias) chosen for transistors or tubes in amplifiers is optimized by the designer for low impedance loads, high impedance loads, or a compromise of the two."

but did also state "Lots of opinions fly around, often contradictory".

At the end of the day, I'm going to let the expert decide (i.e. Glenn) and if Glenn also says the output transformer should have a 32 ohm tap, then I'm going to go with that. Asking these questions has helped with my learning, so thanks again for the additional info.

I can tell you from experience that it's better to let Glenn decide than to tell him what you think you want. Glenn's amps sound good for a reason, he'll steer you in the right direction.