[TLO]

Got my ken-rads, at first I had a shock, I thought one side was DOA, swapped them around and they are playing music beautifully, any thoughts on this matter? Dirty connectors perhaps? I have a really good first impression of the sound itself, I hope they don't die soon


don69-andy only had a single MELZ 1578 tube left, so I might be messaging you on our local marketplace soon, depending on the MELZ situation... unless you got another pair you wanna let go . Is the ECC33 a suitable replacement if my amp's literature only states it accepts ECC32?

Yes, if it can run 6SN7 or ECC32, it can defintely run ECC33. ECC33 runs very much cooler than ECC32, in fact even cooler than 6SN7.
6SN7 - 6.3 V, 0.6 A, AF = 20
ECC32 - 6.3 V, 0.95 A, AF = 32
ECC33 - 6.3 V, 0.4 A, AF = 35
BTW, I have sold off all of my MELZ 1578, none left.

 

[Isaacc7]

I have several different 7AF7’s that I picked up several years ago after reading some forum threads that raved about them. Been long enough that I don’t remember specifics, only that I wasn’t terribly impressed either and much preferred the 7N7’s I was playing with at the time. From what (little) research I did it appears they weren’t all that popular back then and subsequently not made in big quantities which may be why they are scarce today.

I tried the black plate version that I have and I wasn't impressed. Sounded flatter, highs aren't as extended. Of course it is just one tube, maybe a different one would be better. Going back to the grey plate and the difference is obvious. I'm impressed by the depth I get out of this tube and the midrange is... vivid? It's like the colors have been turned up. The 14af7 is cheap enough I'll get some in and see if there are other variations.

 

[Isaacc7]

One mildly interesting thing about the 14af7 is that I can't see the heater. If it wasn't for the readout on the power supply I would think that the filament was gone. Honestly probably wouldn't have even tried playing music if I didn't see a glow.

 

[ARCXENOS]

I have been offered a pair of MELZ 1578, the plate construction seems to be the right one, correct? Any advice would be welcomed

 

[toddc2]

The shiny black plates with holes look proper. The mica’s should be rectangular with a small tongue on each side (instead of oval) and the top supports should be longer skinny supports. From what I understand these are not 1578’s.

Others may chime in as there have been reports of multiple configurations. Confusing to say the least.

 

[TLO]

I have been offered a pair of MELZ 1578, the plate construction seems to be the right one, correct? Any advice would be welcomed

MELZ1578 should look like this...first one the left.
https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/post-17055619
Here are some pictures of those I have sold

 

[Galapac]

I have been offered a pair of MELZ 1578, the plate construction seems to be the right one, correct? Any advice would be welcomed

What you are showing looks to be the cheaper 6N8S Melz which can be had for no more than $60 and sometimes less.

 

[Isaacc7]

Got a followup from Mr. Jesse about the 2c50:

"All of the 2C50 tubes were made by Bendix. They were contracted by Raytheon for military stock orders, hence the “CRP” Joint Army Navy designation and the Raytheon numbers on them. The tip off is the base, it is a proprietary Bendix material that was heat, vibration, and moisture resistant and was always a marbled light tan color, different from other brands of military tubes with the brown micanol bases."

So I'm not sure where he got the info but he is a pretty well regarded tube vendor. I've put the 2c50 back in the system to try to burn it in. Bendix tubes seem to have the reputation of requiring a long burn in time. I'm not a 100% believer in tube burn in but figure I will give this tube a fair shake. Paired it up with some Sylvania 5933 which I have found to be a very "tubey" sounding tube. Warm and fat bass. I'm getting some intermittent noise from one of them but the combo seems to be working out. Both input and output are NOS so if burn in is a thing they'll do it together.

 

[bcowen]

I have been offered a pair of MELZ 1578, the plate construction seems to be the right one, correct? Any advice would be welcomed

Those are 6N8S with perforated plates. Not usual for the 6N8S variety, but not 1578’s either.

That said, I have no idea what makes the 1578 sound “better” than the regular 6N8S. The mica shape and mica support scheme shouldn’t influence the sound. Probably the plate construction and materials more than anything. And if so, those might sound just as good as a 1578.

 

[ARCXENOS]

Those are 6N8S with perforated plates. Not usual for the 6N8S variety, but not 1578’s either.

That said, I have no idea what makes the 1578 sound “better” than the regular 6N8S. The mica shape and mica support scheme shouldn’t influence the sound. Probably the plate construction and materials more than anything. And if so, those might sound just as good as a 1578.

Actually those steel brackets are vibration blockers only. I mean they were created for those 6n8s that must be used in space ships or submarines where vibration can be. From my 15 years experience the better tubes are the older ones. And the oldest are without steel brackets. I offer you really vintage tubes from 1954. The oldest 1578 with steel brackets structure are from 1975.

Was what I was informed by the seller, but that said, I still requested for the ones labelled as "original", lets see if the seller can obtain any left from his stock...

 

[brokemember]

What you are showing looks to be the cheaper 6N8S Melz which can be had for no more than $60 and sometimes less.

What would be a fair price for the 'real' Melz 1578?

And are there any specific vendors that are recommended?

 

[bcowen]

Was what I was informed by the seller, but that said, I still requested for the ones labelled as "original", lets see if the seller can obtain any left from his stock...

Well, the seller is either misinformed or is misinforming on purpose. I have a 1956 1578 in my amp right now. I have a 1963 in the stash. And I’ve seen far more 1578’s in Ebay listings made prior to 1975 than after. While true 1578’s from different years sound different, a 1578 is a 1578, and what you’ve pictured are not them.

 

[bcowen]

What would be a fair price for the 'real' Melz 1578?

And are there any specific vendors that are recommended?

Seems like they are $150 -$200 these days from most sellers. You might get lucky and find one for less ($100 maybe), but it will take some patience. I don’t have any particular seller to recommend, sorry.

 

[ARCXENOS]

Well, the seller is either misinformed or is misinforming on purpose. I have a 1956 1578 in my amp right now. I have a 1963 in the stash. And I’ve seen far more 1578’s in Ebay listings made prior to 1975 than after. While true 1578’s from different years sound different, a 1578 is a 1578, and what you’ve pictured are not them.

Which is why I am glad I asked this thread before continuing with anything, I appreciate everyone posting. Just out of uncertainty, I will insist on the variant with steel brackets and dual mica ledges

 

[ThanatosVI]

Seems like they are $150 -$200 these days from most sellers. You might get lucky and find one for less ($100 maybe), but it will take some patience. I don’t have any particular seller to recommend, sorry.

The price is much better digestable than I thought, but doesn't help if one can't find a trustworthy source.