Sonic Frontiers SFL-2 Preamp

braxus said:
I've read in more then a few comments this pre is supposed to be very dynamic. So it seems to me like I got crappy tubes in this thing causing my sound quality issues. Getting good 6922 tubes would be a problem, as they are becoming harder to find. This pre needs hearty tubes to last. And usually when installing new tubes, this pre needs to be rebiased. So now I have some thinking to do. If my pre sells on Monday, I think I'll get the modded one for sale. If it doesn't sell, I'll just get mine fixed with new tubes and possibly a few mods.
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I wonder how this would sound with AU7's in it, should be able to bias them in. Louder then a AT7 but not as gainy as a AX7
 
Well I sold the SFL-2 I had just this afternoon. I tried to contact a guy selling his YBA preamp, but its been days since he last talked to me. So I ended up putting a large deposit on the upgraded SFL-2 that was for sale. Just got a small amount to go on it and I should have it in the second half of January. We'll see if better newer tubes will make the difference or if I'll still be disappointed in the preamp. I've had many many people state this pre is very dynamic, so my one must of had bad tubes in it. The seller I got my last one from isn't doing a darn thing to reimburse me for buying one with bad tubes. I've been told I should have budgeted an extra amount to replace the tubes anyway. Nice. I ended up losing $100 on this sale. Live and learn. The guy I sold my current SFL-2 to, is planning on replacing the tubes in it anyway, so I'm safe there.
 
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That was a quick sale, Scott. I hope the next SFL-2 you are getting will be the one that does the trick for your system.

Nando.
 
I hope it does the trick too Nando. I had to act fast because the modified SFL-2 had 3 offers on it as of today. The seller was holding out for me because I was the first one contacting him on it. He took my down payment for it today, so its mine once its paid off.

These units seem to be fairly popular. I had 2 offers on mine within the week of listing it only locally. Plus 3 offers on the one I'm buying. All within the past week. So this preamp has to be good for that much hits so quickly. Let's hope I'm happy with the next one.
 
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I was taught that preamps shouldn't add much coloration to the sound, that is what processing and equalization are for, and why integrateds and receivers have tone controls.

Now they DO, of course, but they aren't supposed to alter the sound so much that a really noticeable difference is perceived versus a straight input to the amp.

Getting 8 tubes to dance to the same tune is also kind of a bummer to me. I've had many tube audio items from simple AM radios to a swingin' Hoffman Stereo-Fi console (made in Boss Angeles, USA) and I haven't found one that was finicky in any respect such as that.
 
braxus said:
I hope it does the trick too Nando. I had to act fast because the modified SFL-2 had 3 offers on it as of today. The seller was holding out for me because I was the first one contacting him on it. He took my down payment for it today, so its mine once its paid off.
American made and vintage nos tubes that will work fine. The
These units seem to be fairly popular. I had 2 offers on mine within the week of listing it only locally. Plus 3 offers on the one I'm buying. All within the past week. So this preamp has to be good for that much hits so quickly. Let's hope I'm happy with the next one.
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Hello Scott. That is a fine preamp you have there. I'm sure the problem with the first one was those cheap JJ tubes someone swapped for the originals. Did you ask what tubes are in the new unit you are receiving? I believe these preamps came with Valvos from the manufacture. But there are some others that will work. The quality of the tubes is important. And the bias has to be set on two of those in there which should be a matched pair. Hopefully you will also receive the manual which will show you how to set the bias adjustment.
 
The new SFL-2 I'm getting has eight NIB Amperex Bugle 6DJ8s which he has about 100 hours on them. The preamp was sent to Parts Connexion for factory adjustment.
 
Hola Scott, I read a thread over on the Martin Logan forums and someone there knows a Sonic Frontiers line 2 guru, I'll pop over there tomorrow and see what else I can find out for you buddy :toothy5:
 
Stu,

Did you ever get a hold of that guy about the Sonic Frontiers stuff?

Its funny after I gave the go ahead to purchase the upgraded SFL-2, the YBA guy emailed back stating his still will sell his preamp. I had to tell him its a bit too late. He has since sold the YBA, but there are two more for sale online. I'm going to get the YBA for backup, and use it in my secondary system. Unless I don't like the sound of the upgraded SFL-2, then the YBA will be put into the main system.
 
Well I paid off the upgraded SFL-2 preamp. It's been shipped and is on its way. Should get it the last week of the month.

Buying this all used sure saves a lot of money for high end gear. The new stuff today really isn't anything better (unless its tubes) then stuff from 20 years ago, so might as well save some money.
 
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Well I got the second SFL-2 preamp home today. I openned it up and something I noticed concerned me. 6 black caps to me look like they may have leaked. My previous unit did not look like this. Can someone looking at the pictures confirm my suspicion is correct? I may need to contact the seller to talk to him about this. I did plug the unit in to see how it sounds and its better then the last unit, but I haven't really put it to the test to see if dynamics are still being compromised. Dynamics are better from the short test I did. I did hear a couple quiet pops when no music was playing. Should I be concerned about that or is it just a tube thing?
 

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Yes this pre has been modified by Parts Connexion to do the SE+ upgrade on it. So yes its been worked on before.

Can you point out where LR6 is? I need to know if there are more issues then just those caps I noticed.
 
Circled in the photo.
 

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So I take it the solder joints should be gone over to fix the messy ones?

I had a second listen, this time with more music and a bit louder. Dynamics are almost as good as solid state. Not much of a difference to really complain about it. Lots of air to the music, but not sure about depth or space to the instruments yet. I can't place one instrument in space compared to others yet. Only more listening will help me see on that. The unit sounds good, definitely better then the last one I had. Can't say for certain if it will be any better then the YBA pre I was planning on getting. That pre will be in limbo on purchasing it till I figure out my living situation this year. As mentioned, I may or may not be moving come mid this year.

All I can say is I have a nice system now, enough to piss off the neighbors in an apartment. :P
 
Well I've been in contact with the seller and also some techs. The seller had no clue there was internal issues with the pre he sold me. Of course he is going to say that, but he claims he wasn't dumping the unit. I'll let it go. Can't cry over it now that its in my hands. I just find it hard no one noticed the Solen caps issues while it was in his hands. But he may have not been very tech savvy either, other then the fact he did swap the tubes in this thing when he owned it.

The two techs stated Solen caps don't like heat, and I've been told this preamp looked like it was not in a well ventilated area, causing heat damage with the internal parts. I've been told to expect $300-400 to fix these issues and replace needed parts. Then it should be in the state I was expecting it to be sold to me to.

When I finally complete building my main system, I may at some point get a new rack made up. My current rack isn't making the best space available for the components I'm using. Shame to get rid of the rack I have now, because its well built (custom made) and cost a lot to have made up. Any new rack will most likely be between $700-1000 to get a new one made up.
 
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