[gibosi]

There is also the GZ37 but costly.

I measured the Mullard GZ37 at 27 volts, the more costly Cossor "Fat" GZ37 (53KU) was 22, and the Mullard GZ32 was 20.

But with respect to the GZ32, one must be careful to purchase a real Mullard GZ32, and not the Brimar 5V4G, with perforated plates. Unfortunately, the Brimar is often labeled as a GZ32. And worse, the 5V4G is rated at only 175ma and cannot provide enough current to run the OTL with 6AS7G installed. On the other hand, a real GZ32 is good for 250 to 300ma in the OTL.

https://frank.pocnet.net/sheets/030/g/GZ32.pdf

 

[Monsterzero]

@2359glenn I dropped you a PM several days ago inquiring about your amps...If you could respond or let me know of a better way to correspond I'd appreciate it.

 

[jekjek]

I measured the Mullard GZ37 at 27 volts, the more costly Cossor "Fat" GZ37 (53KU) was 22, and the Mullard GZ32 was 20.

But with respect to the GZ32, one must be careful to purchase a real Mullard GZ32, and not the Brimar 5V4G, with perforated plates. Unfortunately, the Brimar is often labeled as a GZ32. And worse, the 5V4G is rated at only 175ma and cannot provide enough current to run the OTL with 6AS7G installed. On the other hand, a real GZ32 is good for 250 to 300ma in the OTL.

https://frank.pocnet.net/sheets/030/g/GZ32.pdf

Thanks for the info Ken
I did not know gz32 can provide 250ma

 

[gibosi]

Thanks for the info Ken
I did not know gz32 can provide 250ma

The fact that the Brimar 5V4G is commonly labeled as a GZ32 has created considerable confusion. On more than one occasion, people have had them fail catastrophically in a Glenn OTL, and came to the conclusion that the GZ32 was not suitable for use in the GOTL. However, a true GZ32 is perfectly adequate, and even better, Mullard's version is a very good sounding rectifier.

 

[attmci]

I measured the Mullard GZ37 at 27 volts, the more costly Cossor "Fat" GZ37 (53KU) was 22, and the Mullard GZ32 was 20.

But with respect to the GZ32, one must be careful to purchase a real Mullard GZ32, and not the Brimar 5V4G, with perforated plates. Unfortunately, the Brimar is often labeled as a GZ32. And worse, the 5V4G is rated at only 175ma and cannot provide enough current to run the OTL with 6AS7G installed. On the other hand, a real GZ32 is good for 250 to 300ma in the OTL.

https://frank.pocnet.net/sheets/030/g/GZ32.pdf

Brimar 5V4G, re-branded Russian tube?

 

[gibosi]

Brimar 5V4G, re-branded Russian tube?

No, the 5V4G / CV729 was manufactured by Brimar, and in those amps that can use it, many consider it to be a good sounding rectifier. While 175ma isn't adequate to power the GOTL with 6AS7G installed, it can be used with a quad of 6BL7. And of course, it is fine in the GEL3N.

 

[attmci]

The left tube is a re-branded Brimar.

Yes, I love the CV 729 on the right.

 

[2359glenn]

The fact that the Brimar 5V4G is commonly labeled as a GZ32 has created considerable confusion. On more than one occasion, people have had them fail catastrophically in a Glenn OTL, and came to the conclusion that the GZ32 was not suitable for use in the GOTL. However, a true GZ32 is perfectly adequate, and even better, Mullard's version is a very good sounding rectifier.

Some years ago when I used 5U4 rectifier in 300B amps. It was powering two 300Bs and two C3gs that add up to 200ma
at twice the voltage used in the OTL 425 volt or 850 PIV. Someone put in a GZ32 and it violently exploded on the inside.
I only recommend using this tube in the EL3N amp.

 

[UntilThen]

ECC31 and Tung Sol 5998 sounds really good in Glenn's OTL amp.

 

[whirlwind]

Well I'm definitely a believer now. Another added bonus (for me) is that the slightly elevated B+ has noticeably dropped the static (scratchy) noise level in the driver tubes. I would recommend that new GEL3N owners burn-in their amps using the 3DG4 (YMMV.)

For $4 each for this rectifier...it is a no brainer!

 

[leftside]

ECC31 and Tung Sol 5998 sounds really good in Glenn's OTL amp.

Sounds good in most amps Most tube combos you are recommending are also the favorite combos in my (well actually my wife seems to have taken it over...) WA22.

 

[mordy]

One of my grandsons got into Hi Fi and brought over an Audeze LCD-3 headphone for me to listen to.

It looks exactly like this one. I did not realize how expensive they are, and listened to them without any price prejudice lol. Anyhow, I would only describe them as honestly as I can in any event.
Pulled out my Elise tube headphone amp since I thought it would have enough power for the LCD-3. First I compared it to the Sennheiser HD650, but it was too different to compare with - needed something more detailed, and took out my Beyerdynamic T1 Gen1.

The LCD-3 headphones felt heavy but very comfortable.
Planars are supposed to have very good bass, and the bass is exemplary, detailed, and full bodied, much more so than the T1. However, I felt that the mid range was sweeter with the T1, and the treble was less emphasized than on the T1. (It occurred to me that I could flesh out the bass on the T1 using tone controls.)
I ended up thinking that the bass was more prominent and the mid range and highs were not as much to my liking as the T1. The detail was about the same with both phones.
If you like superlative bass, this is the way to go, but personally I would prefer a different presentation.
Again, I did not try to tweak the amp to better suit the Audeze and just used my GEC saver tube complement - a pair of 60's Fotons and a pair of 50's RCA 6AS7G.
Only spent some 30 minutes with a brand new pair so my impressions may change over time. And yes, the LDC-3 cost almost $2000.....

 

[UntilThen]

Sounds good in most amps Most tube combos you are recommending are also the favorite combos in my (well actually my wife seems to have taken it over...) WA22.

It's no surprise they sound good in other amps too because these are quite special sounding tubes.

What made me smile when I look at the Glenn OTL is that I am only using one NOS ECC31 driver. The tube that came from Langrex is so perfect even the lettering is still 100%.

The 5998 didn't last long in the sockets because I'm back to using 6BX7s again with a GEC B36. Those other power tubes such as GEC 6as7g and Tung Sol 5998 are good, very good but I somehow prefer the more incisive tone of the 6BX7.

 

[JazzVinyl]

Know what you mean about the "incisive tone" of 6BL/BX7's...faster/sharper/more dynamic.

 

[UntilThen]

Mordy, glad you had the chance to listen to the LCD-3. I've only listen to LCD-2f. At Addicted To Audio, they have the whole Audeze range including LCD-4 but I didn't ask to listen to the 3 and 4 because I didn't want my wallet to take a bigger hit.

You need a period of adjusting to the much different sonic signatures when going from T1 to LCD-3. That said, you might be more a 'details' person just like me. Prior to getting Glenn OTL, my fav headphone is the ZMF Eikon but now HD800 has reclaimed pole position. I'm a firm believer that when evaluating a gear, you need to consider the whole setup. Source, amp, headphone and tubes. To a lessor degree headphone cable. Let's not talk about fuse. You have to find the right balance of romantic and dynamic in the whole chain.

However what surprise me is that LCD-2f is gaining favour with me again.