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Attention Sonic Frontiers owners.....

Hi, I have recently been corrected of a mistake regarding the Sonic Frontiers Line series pre/amps and Power Series of amps. I was always informed that the most important tube spots for these products was the rear most LV1, V1 rear positions. After trying a little experiment with my tube amp I became curious about a tube swap that I performed. I emailed SFI and I was then told of the circuit topology. It is broken down like this for the Line 2 and Power 2:
Line 2:
V1 and LV1 – Input buffer
V2 and LV2 – Gain stage
V3 and LV3 – Cathode follower
Power 2:
V1 and LV1 – input buffer
V2 and LV2 – voltage amplifier
V3 and LV3 – driver
V4 and LV4 – cathode follower.
I’ve since started using the gain stage slots for my better tubes and have been pleasantly surprised. I recommend that you try the same if you own one of these products. I'm not sure about the Line1+3 or the other power series of amps but I recommend you email SFI about them for more details.
Greg
gsselling
gsselling OP
29 posts
 
Hi Jim, wow, you've really dug into this with all of your might!!! This past week I took out my Siemens E188cc's from my amp and have been running both pairs in the LV1+2 and V 1+2 slots of the pre amp. I have found that they are much better paired like this while running all EH 6922's in the Power 2. I have ordered some more pairs of them to give them a shot in the amp to see what kind of results that would bring. Yesterday I finally got around to doing some room treatments in the way of Auralex absorption panels and some of their bass traps and the improvements that has brought is astounding. I will post more on all of this at a later time and I'll put up some pictures on system here.
Regards
Greg
nghiep's avatar
nghiep
79 posts
 
I have the SF power 2 amp and SF says that the 2 front 6922 run hot. Had anyone experienced the capacitors under the 2 front tubes got hot and the cap. the labels pealed off?
elduende14
51 posts
 
Dear Gsselling,
I have the Line 2SE+ Preamplifier.
As you saw the front line (L3 and LV3) is the less important and really don´t affect the sound. So the problem are line 1 and 2. Both affect the sound, so I bought quads Siemens E88CC and quads Amperex 6922PQ White label made in USA. (for the line 3 I use a pair of Reflektor 6H23NEB)
I tried the four Siemens and then the four Amperex. For me, I prefer the sound of the Amperex but the Siemens have less noise and microphonics.
So, finnally I combined the Amperex with the Siemens. I put the Siemens in the line 2 and the Amperex in the line 1. So I have an identical tube set to replace them in the future.
For me this combination is the best. Althought I have a very little more texture in voices with the 4 Amperex I have less noise and more analitical with the Siemens in the Line 2.
I hope this help you.
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