LS15 preamp tube position

BillWojo

New Member
Jun 12, 2015
11
0
1
#1
Picked up a nice LS15 preamp that uses 4 6DJ8 tubes. It came with JJ tubes and my experience with JJ is they are best at keeping dust out of the sockets.
On hand I have 6 Tungsram 6299 (NOS) and various vintage 6DJ8 tubes.
I see that many of you folks have newer ARC gear but I'm guessing that in the past some might have had one of these. Does anyone know where the best tubes should be located? V1, V2, V3, or V4?
What amazes me is that even with the JJ tubes it sounds so good. My system is a Sony CD player into a vintage R2R DAC with PCM63P chips, that feeds the ARC preamp and goes out to restored Mac MC40 monoblocks. Speakers are modified HeathKit AS101's, basically they are Altec Valencias in much nicer cabinets.
I'm very happy with this setup, just looking to get the best out of the preamp.

Thank you
BillWojo
 

BillWojo

New Member
Jun 12, 2015
11
0
1
#2
Wow, looks like this forum has run it's course. Not a peep. Figured that there would be a few AR fans giving advise.

BillWojo
 

MPS

Member
Jun 20, 2016
37
5
8
Finland
#3
I would recommend you simply to try out which tube or combination of tubes sounds good to you. I believe positions 1 and 2 are for amplification stage and 3 and 4 for output buffer, so in principle 1/2 should make a bigger difference but ymmv.
JJ is considered to have reasonably good sound for a new production tube but not comparable to those vintage tubes such as Amperex (Heerlen), Mullard (Blackburn), Telefunken etc... Best of those are made in 195x-196x.
I have experience with LS15 and even it being a nice preamp, I would strongly recommend looking into LS26 or REF3 as at least two steps ahead.
 

BillWojo

New Member
Jun 12, 2015
11
0
1
#4
Thanks MPS for the reply. I've been playing with this today and from studying the schematics it does look like V1 and V2 are for the gain stage. As luck would have it I had no work today and a set of NOS closely matched Amperex 6922 gold pins came in the mail.
They have made a very nice improvement, I'm a lot happier with it now. Sounds more like a tube preamp than a SS one. By far the best preamp I have ever had.
I feel lucky to have found this for the price I did, a LS26 or any of ARC's Ref preamps is way out of my budget.
Again, thanks for the advise. Now I'm wondering if getting another set of the Amperex's for V3 and V4 would make even a bigger improvement.

BillWojo
 

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