| Author | Message | ||
| Michael Kaus |
Steve-have you seen any circuit modifications that would allow for more bass response out of said amp? I can change the .22 cap on the bass control but I think it really lies in the stages after the first LM307 and just infront of the second. It just doesn't have any bass response, even when used with 12's or 15's. Any suggestions? Tubes are new JJ EL34L's biased at 14-15mA. Numerous sets of tubes have been tried and these sound the best. None had any real bass response. Mike}} | ||
| nep2ne |
I get so much bass response from my 65-210 that I think I might have blown a capacitor or are near to doing so. I play an archtop/jazz-style guitar through the deepest pickup. And I tune a half-step lower anyway. What I get is an evil buzzing sound over the entire amp -- it's not the speakers, as it's happened through an external cabinet, and it's not the tubes either. I just bought a second amp -- this one is identical except it's a 100W. I'm hoping the added power of the amp will be enough and I wont come near to blowing anything this time. | ||
| Steve Kennedy |
If ANY series capacitors in the signal path have reduced in value or if any parallel capacitors (to ground) have increased in value then you will lose bass energy. You are either losing it by not allowing it to pass through to the next stage or you are "bleeding" low frequency energy to ground and preventing it from even existing beyond a certain point in the signal path! Try putting a low frequency sine wave (from a generator or synth) into the amp's input and use a scope to "walk" through the circuit by following the schematic and find out where you are losing the low frequency energy. Problems like this have no simple solution... you have to find out what is occurring by troubleshooting. Steve | ||
| Steve Kennedy |
In regards to the overabundance of low frequency energy and the "evil buzzing" sound not caused by the speakers themselves, I would guess it is probably a capacitor (in the preamp signal chain) or a power supply filter cap problem. The filter capacitors (electrolytic type) in the power supply do two things... they filter out hum and they act as a storage reserve that can be used to dump more instantaneous bass energy to the system when needed. If the caps are 20 years old, they have dried out and while they still may be good enough to filter hum, your amp may not be able to deliver the bass energy you need because the resevoir is dry! The result is premature overload and stage clipping because you are constantly asking for more energy than the amp can deliver. If you turn down the volume the problem should get better or disappear. Getting good full power performance at bass frequencies requires good speakers, a preamp stage with good low frequency characteristics and a healthy power supply. Steve | ||
| mike kaus |
Thought I'd put this here-don't know why. I'm sure glad my last name isn't 18! Seriously, it's a shame we've been invaded by this crap. I usually look for the new entries and they're all this gay crap. I guess it's a sign of the times but I don't HAVE to be happy about it. Mike. | ||
| Steve Kennedy (admin) Username: admin Registered: 03-2002 |
Well this is the FOURTH time this system has been attacked and the valuable resource this system provides has been diluted and scarred. I will be scrubbing the system clean of all such garbage and making all posting (except the Urgent Help and System Questions topics) by Registered members only. I know this will result in a flood (or a large trickle) of e-mail asking for registration but it is the only way I can deal with and stop this pollution. These gambling drug-infested gay spammers should be hunted down and dealt with... not because of who they are but what they did to the purity and freedom this system represented. This may change when I can get the time to upgrade the system software that has some new tools that might help but until then, no new posting without registration. This could take some time for me to dole out as I am quite busy right now. Steve |
Tue, 03/25/2014 - 09:57
#1