[Galapac]

dac -> 339i -> speaker amp -> he6

I still don't follow. So you had something like this with a 1/4 adapter I assume plugged into the 339i:

and the RCA end into another amp, of which you had the HE6 plugged into and blew them?
Was the amp the HE6 were plugged into turned on and volume up?

 

[Bruc3]

Was the amp the HE6 were plugged into turned on and volume up?

He mentioned it was a Adcom 545 power amp he had it plugged into like below:
https://www.kenrockwell.com/audio/adcom/gfa-545-ii.htm

AFAIK the poweramp does not have its own volume control, it needs a pre-amp to control the volume.

 

[telecaster]

Adcom 545. There was no pop noise. Just one tiny click sound like the clock ticking. It just died peacefully.

For some reasons and maybe others can confirm too. In the past when I use my 339i as a pre-amp out using the line out, there is a noticeable noise floor that does not change when I turn the knob (even when it is zero).

It seems like it is a vintage amplifier from the 1990ish? If yes, there is a good chance of the electrolytic in need of service. As time goes by they can drift or leak, making the amp a DC offset at the speaker terminal. You won't hear the pop noise if you don't plug the speakers obviously. If the DC voltage is present at the output it will kill headphones instantly, and can damage speaker. You can measure the DC offset at the speaker terminal, and you can plug speaker to hear if there is a loud pop noise.
Sorry for those HE6, but plugging headphone to speaker taps is a risky business, especially with old amps.

I did a quick read about HE6 on power amps. Did you power the Adcom after you plugged in your HE6 onto it?

 

[telecaster]

I still own a custom LF339 (6C5/L63 version) and I recently ordered the 339i from mass drop.







At this point, I've owned all iterations of the amp and have tons of adapters.

EF80 to 6SJ7
EF86 to 6SJ7
EF86 to 6C5
6SN7 to 6C5
76 to 6C5



Also a lot of tubes:



Even some especially rare ones like these Genalex Z729 (EF86)



Each of these come with piece of paper with hand written test values.

I haven't been around much mainly because of free time. The elekit amps have always been on my radar as I like doing kits. Previously I've done the bottlehead crack and the transcendent sound masterpiece amps.

Impressive, I love all those tubes, especially when they are in boxes with measurements! Bravo!
About the Elekit, the more I look at it, the more I want to design my own amp or buy one with the tubes I am looking for.
There a nice 300b amp nowadays too from China that looks the bomb.

Anyway everytime I listened to 339 I feel I really don't need to invest in another amp for now! Many many other things to buy first, like a nice ARP 2600 synth from Behringer for example haha!

 

[telecaster]

Side by side with LF339i, the Elekit is very comparable but ultimately wins in depth and height of soundstage. I didn't know LF339i is lacking in those until I hear the TU-8200 with Psvane 12au7 and Gold Lion KT88. It's holographic and 3D in the truest sense of those terms. Elekit is also better in resolution and details. Notes stood out a lot more clearly. It's airier. LF339i is darker and warmer. Now I did not notice that of LF339i until I hear the Elekit TU-8200. Now with KT77 tubes, dynamics have just gone up another notch.

Having said that, I'm not getting rid of LF339i because when I listen to them side by side with LCD-3f, LCD-X, He1000se and HD650, I can see myself loving both but the TU-8200 wins here for me and I've just started using 3 power tubes. More to come...

Both are very powerful... the Elekit 8200 more so. Understandably so because 8200 is 4w in triode mode, 8w in Ultralinear mode and 8.2w in Pentode mode. It's also supremely quiet and feels just lukewarm on the chassis after hours of operation. Not HOT like the LF339i.

With your skills, upgrading and putting together the Elekit 8200 is much easier than upgrading LF339i. Get it and see for yourself.

Thanks for the impressions! Yes the Elekit looks nice for sure! Maybe one day! ^^

 

[telecaster]

I don't think converting 6SJ7 to 6J5 is terribly difficult. Maybe @xmdkq or @telecaster can enlighten us with a diagram of sorts?

The 6J5 pinouts is as follow

and the 6SJ7 pinouts is like this

First a warning, if you don't understand the high voltage involved in tube amps,or you don't understand what those diagrams are for, please don't do the conversion yourself ^^


- F stands for filament in french. Or can be H for heater.
- G for Grid
- A for Anode (which is the P for Plate=Anode) ,
- K for Cathode,
- M for masse in french, which is the S for shield when there is a metal tube protection around the tube!

The pentodes are strapped like this (I believe) :
Connected together G2 and G3 and the Annode.

The you need to change to resistors value, the last two resistors in the power chain before the driver tube.
200ohm ---> 100ohm
30Kohm ---> 33Kohm

That's it ^^
Good vids to understand a tube amp :

 

[UntilThen]

Thanks for the impressions! Yes the Elekit looks nice for sure! Maybe one day! ^^

I've just purchase the accompanying preamp / phono stage called TU-8500 to partner TU-8200. A Bendix 6080wb new pair is coming to me this weekend. I like Bendix in the LF339i. Love the dark and warm tone of that tube.

 

[hp4fun]

It seems like it is a vintage amplifier from the 1990ish? If yes, there is a good chance of the electrolytic in need of service. As time goes by they can drift or leak, making the amp a DC offset at the speaker terminal. You won't hear the pop noise if you don't plug the speakers obviously. If the DC voltage is present at the output it will kill headphones instantly, and can damage speaker. You can measure the DC offset at the speaker terminal, and you can plug speaker to hear if there is a loud pop noise.
Sorry for those HE6, but plugging headphone to speaker taps is a risky business, especially with old amps.

I did a quick read about HE6 on power amps. Did you power the Adcom after you plugged in your HE6 onto it?

For the record, I had been using

dac --> adcom --> he6

for a great result and enjoyed for a few weeks.

Then yesterday I thought I wanted to put 339i into the sound path. I hesitated at the beginning, and used the sp200 as the stepping stone

dac --> sp200's se output --> 3.5mm to RCA adapter --> adcom --> he6

and it worked great too!

So I started to replace the sp200 by the 339i. Then the hp was gone

Yes it is a risky business.

 

[hp4fun]

I still don't follow. So you had something like this with a 1/4 adapter I assume plugged into the 339i:


and the RCA end into another amp, of which you had the HE6 plugged into and blew them?
Was the amp the HE6 were plugged into turned on and volume up?

Yes. the power amps do not have volume control so I used the volume control in dac / 339i.

And this is something I don't quite understand in the 339i.

Theoretically, the pre-amp out needs to deal with a power amp that has 10k+ ohm input impedance. The headphone out only needs to deal with ~100 ohm impedance.

Therefore if I connect the headphone out to an power amp, shouldn't it be 10x difficult to drive and less likely to over power the speaker / headphone?

I read similar discussions long time ago about the pre-amp for power amps. Basically the headphone out was not powerful enough by design.

Given I did make it happen to connect the 339i pre-amp out to the power amp (not great result though), I think it is safe to connect the headphone out to the power amp.

Maybe the OTL design is different. or quite different I should say

 

[hp4fun]

I know it is a 339i thread, but since @UntilThen mentioned this already,

https://www.ebay.com/itm/Rare-Pair-MWT-Marconi-6AS7G-A1834-Valves-Tubes-Used-Tested/184639056281

Price seems quite reasonable.

 

[UntilThen]

Did you get that hp4fun ?

 

[UntilThen]

So I started to replace the sp200 by the 339i. Then the hp was gone

Yes it is a risky business.

What do you mean gone? Your He6se is dead now? I wouldn't worry about using the LF339i as a preamp. I'm just using that strictly as an amp and that's where it excels.

 

[hp4fun]

What do you mean gone? Your He6se is dead now? I wouldn't worry about using the LF339i as a preamp. I'm just using that strictly as an amp and that's where it excels.

Agreed, and my misery was because I used headphone out as preamp.

 

[Galapac]

Did you get that hp4fun ?

Person that bought those was a reseller. Look at the feedback.
dan198745 (34655)

I took a pass on those as they weren't matched and the specs on one were below my minimum.

Valve 1) Ia 74/90 - Gm 5.4/5.9

Valve 2) Ia 51/88 - Gm 4.5/5.6

 

[UntilThen]

Agreed, and my misery was because I used headphone out as preamp.

Extremely sad. I've not blown a headphone before.

Person that bought those was a reseller. Look at the feedback.
dan198745 (34655)

I took a pass on those as they weren't matched and the specs on one were below my minimum.

Valve 1) Ia 74/90 - Gm 5.4/5.9

Valve 2) Ia 51/88 - Gm 4.5/5.6

That's a low reading and not one I'd buy. So beware if it pops up for sale again.


I'm getting these Bendix 6080wb as a 2nd pair.