7N7 or 7AF7

[John Roman]

Was looking at possibly converting my extended foreplay 3 to 6SN7's and began to notice these loktals. Come highly recommended by Dick Olsher.
Would these also be suitable in my Paramount's. Any suggestions on brands and your experiences?
It's 3 am and I'm listening to Diana Krall.  The Paramount's sound great can't wait to get my BassZilla's finished. The G2 ribbons came in last night but realistically completion is at least a month away. Still looking for an amp to handle the bass load. I want to bi-amp the system, ideas?
Starbucks open in 90 minutes.....
John

[Grainger49]

Poster Paully will chime in.  He has converted two such preamps to 7N7 and loves them.

[Paully]

We tried the 7AF7 at one point it seems like and thought it was ok.  In the end I gave my stash away to a guy in Italy.  I liked the 7N7 a lot and use that.  As you know the 7N7 is the loctal equivalent of the 6SN7.  It is somewhat cheaper but the tall bottle square plates (especially the square black plates) are getting somewhat hard to come by.  There are National Union out there but they are pretty rare so in reality the only flavor that you are going to easily play with is Sylvania and the only tube rolling are the three or four types of 7N7 from that manufacturer.  The tall bottle have a reputation as being better than the shorter triangle plate version which I agreed with. It seems to me that you might want to compare the price of 7N7 tall bottles to various 6SN7 that are more readily available.  I am not an expert on 6SN7 but it seems to me there are still oodles out there that are decent at reasonable prices.  So the savings, as long as you are ok with not getting the super premium 6SN7, aren't huge and the tube rolling options in the 6SN7 are much greater.  In the end you might decide to do 6SN7 and us an adapter for the 7N7.  I don't mean to equivocate, I really like the tube so I don't worry about being able to tube roll like the 6SN7 but you might.  If that doesn't concern you then by all means, I can tell you with certainty that when I switched from 12au7 to the 7N7 I was happier with the sound but I like that warm lush tube sound.

And my only experience here is with Bottlehead preamps.  PJ has a thread you should find in the Paramount section about converting to 6SN7.  Using that it would just be a pin-out change for 7N7.

[Paully]

By the way, there are a few decent tall bottle 7N7 for sale on ebay.  And even a couple of short bottles that they made with the square plates (the square plates really do seem better than the triangle plates).  Take a peak at the prices for those and also the prices for the completed auctions, which are pretty standard for 7N7 and compare to the 6SN7 that you would want to use and decide for yourself whether they are economical enough to justify the Sylvania only option.  It is a worthwhile and fun experiment no matter which was you go.  Let us know what you do.

[John Roman]

Thanks guys,
Good info. I'll definitely  take a look on Ebay for probably all these. Any thoughts on  bi-amping  the bass drivers on my speakers
John

[Paul Joppa]

For bi-amping, the first question is what crossover functions do you need? If you can do it passively at line level, that would be probably the best sonically, but is quite limited in what functions are achievable.

[Lee Hankins]

John, like Paully I went through a loctal tube (7N7, 7F7, 7AF7, 6CG8) rolling adventure.  Sylvania and National Union were the only makers of the 7N7, according to one "expert" source, all tubes not labeled National Union were made by Sylvania.    As Paully stated there were rectangular and triangular plates, tall and short bottles.  Personally I didn't fine their sound anything special (especially the 6CG8), IMHO not worth the effort; even though I did spend considerable time and money on this tube rolling adventure, but it was an interesting experiment.  The bottom line is that a tube that is electrically equivalent does not mean that is will sound the same, always searching for that magical unknown (i.e. cheap) substitution.  

I have found that the 12SN7/12SL7 families are much better sounding tubes so my time and limited tube resources have been directed in their direction.  

[John Roman]

Hey Lee,
I'm considering the 7N7 as it has been recommended by the designer of my speakers. I appreciate your input though.
John

[Paully]

If we all came to the same conclusions this hobby would be really boring and really expensive. 

[RayP]

Years ago I built what I called the tube taster. It was essentially a parafeed design (Edcore transformers) where I could easily switch between 6 different tube types - 76 6N1p 5965 a couple of 6SN7's and 5687.

It was very ugly and quite educational. The main thing I got out of it was that I preferred certain tubes with certain styles of music, so for me there was no perfect tube.

ray

[RayP]

I found some old pictures of the tube taster and a bit of a write up that I did at the time so I have converted it all to a blog.

http://audioratbag.blogspot.com/2011/09/tube-taster.html

I actually dismantled it and built a new one a few years back. I should drag it out sometime and give it a listen.

ray

[Lee Hankins]

Hi John,

I believe that Dick Olsher has stated that his favorite preamp tube family is the 6SN7, so naturally he should like the 7N7.  One has to understand that any recommendation from another individual (especially me) has to be consider biased, we all have different systems and different taste.  I spend a considerable amount of time rolling tubes, something that this annal retentive individual somehow finds enjoyable.  I hope that you did not think that I was down grading the 7N7, I was not.  The 7N7 is a good tube, better in the driver position than as an output tube IMHO, but in all of my systems it just does not stand up to the better 6SN7GT tubes (tung-sol round plates etc.), but we are always trying to find that odd tube for $5.00 that does sound as good as the Tung-Sol round plate or RCA VT-231.

In my extremely biased opinion the 12SN7 family does fit that inexpensive (relative speaking) tube that does sound just as good as the Tung-sol or RCA, they are the exact same tube just a 12 volt version.

The bottom line is that if one does not want to spend top dollar for the better 6SN7GT/VT-231 tubes, then the 7N7 with an adapter is a great bargain.  It actually is a great tube to roll because there are just two tubes manufactors, Sylvania and National Union, each with two plate types and short and tall versions for only 8 tubes total.

I have had the parts for Dick's Basszilla for years, just never got around to building it.  Good luck with yours.