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pace
Senior Member
Username: pace

Post Number: 975
Registered: 4-2004
Posted on Tuesday, January 07, 2014 - 1:54 pm:   Edit Post

Ok, this is bearable, but just noticeable to drive me nuts.

I've A-B'ed both channels, swapping out everything~ cables, tubes, power amp channels, stereo, mono, etc etc… and it's something in the actual circuit. Ch1 is always about 1.5db louder than Ch2. I have yet to take a meter to it, so any help as to where to start, and maybe what voltages I should be seeing would be great!!!!

P.S., the only components that look like they're from two different batches are the Midrange 10K pots.
slawie
Senior Member
Username: slawie

Post Number: 578
Registered: 8-2002
Posted on Thursday, January 09, 2014 - 1:19 pm:   Edit Post

Have you tried raising or lowering the pickup height?
pace
Senior Member
Username: pace

Post Number: 977
Registered: 4-2004
Posted on Thursday, January 09, 2014 - 1:39 pm:   Edit Post

Thanks Slawie, because the end result that I'm hoping for is to run my series instruments through the rig w/out any differentiation between the two channels..... but I haven't gotten there yet..... For now I'm running all my mono guitars into an A/B box going to each channel of the F-2B. Even if I jumper a mono instrument from ch1 to ch2 , ch1 is still louder.

So in a nutshell, no, I haven't adjusted p/up height, because my series instruments haven't factored into the equation yet....
edwin
Senior Member
Username: edwin

Post Number: 1781
Registered: 5-2002
Posted on Wednesday, May 28, 2014 - 1:29 pm:   Edit Post

Any luck figuring this out? I've noticed that my channel 2 is louder and cleaner sounding that channel 1. Channel 1 has a kind of blanket over the sound. I've swapped tubes, cables, etc. I'm thinking maybe the aging caps in the signal path (it's one of the ones made in SF with red capped knobs).
pace
Senior Member
Username: pace

Post Number: 1030
Registered: 4-2004
Posted on Saturday, June 21, 2014 - 6:12 am:   Edit Post

I still can't figure it out, and I've had no time to really check into it....I'm thinking either the padding resistors, or the summing resistors may have deviated from their values....
hieronymous
Senior Member
Username: hieronymous

Post Number: 1385
Registered: 1-2005
Posted on Monday, June 23, 2014 - 9:14 am:   Edit Post

Not sure if I knew this before, but according to the manual, Channel 2 has a 6 db pad.

Actually, the grammar in the old manual is terrible - it says "Inputs # 2 provide 6 db pads. Both inputs # 1 and # 2 on a channel may be used simultaneously, too. In this case both signals are resistively mixed in equal proportions." Does that mean if you use both channels at the same time then the 6 db pad is defeated? Anyway, hope this helps!
edwin
Senior Member
Username: edwin

Post Number: 1792
Registered: 5-2002
Posted on Monday, June 23, 2014 - 10:27 am:   Edit Post

I finally hooked up my F2B to Metric Halo Spectrafoo via a ULN-8 to see how it matched up and it turns out that my F2B is actually pretty much right on. After further investigation, I discovered that my power amp has a channel which seems off. The manufacturer seems to think it's the LP/HP/full range filter switch.
davehouck
Moderator
Username: davehouck

Post Number: 11386
Registered: 5-2002
Posted on Monday, June 23, 2014 - 11:07 am:   Edit Post

Harry; you're mixing up the terms channel and input. There are two channels, A & B. Each channel has two inputs, 1 & 2.

It is the input number 2 on each channel that has the 6db pad. If you plug two instruments in inputs 1 & 2 on channel A, then the inputs are summed so that the 6db difference in input gain is eliminated.

If you plug two instruments into inputs 1 of both channels A and B, then nothing is padded.

If you plug two instruments into inputs 2 of both channels A and B, then the signals from both instruments meet a 6db pad.
hieronymous
Senior Member
Username: hieronymous

Post Number: 1386
Registered: 1-2005
Posted on Monday, June 23, 2014 - 12:30 pm:   Edit Post

Thanks Dave - I got confused! That's why they were using the plural for "inputs" and "pads" - it all makes sense now! Should have looked at the manual while I had my F-2B in front of me!
davehouck
Moderator
Username: davehouck

Post Number: 11387
Registered: 5-2002
Posted on Monday, June 23, 2014 - 1:17 pm:   Edit Post

:-)
pace
Senior Member
Username: pace

Post Number: 1035
Registered: 4-2004
Posted on Monday, June 23, 2014 - 4:00 pm:   Edit Post

Reading the thread on the main page, and Dave's response is what made me go to the PDF, and also this thread... But ch B is lower regardless of tubes, power amp channels, patch cords, etc etc

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