eq_shadimar Posted August 27, 2002 Share Posted August 27, 2002 Ok I finished installing all the upgrades to my Fisher 500B late last night. It has fixed all of the problems I had with the unit except for one (more on that later). I hooked it up to my Cornwalls last night and in general I was very impressed with the sound. The unit is totally quite. Without a source there is no hum coming from the speakers at any volume. The balance and tone functions are working as well as all the other bells and whistles. I listened to several sources and I liked what I heard. I need to do some more listening and I will post the results here. The DFW area Klipsch Forum members are coming over this weekend and I will ask them to post their impressions here as well. The volume control goes from 1 to 10. When listening to the tuner section a volume setting of 2 produces much loudness. To produce the same volume level while listening to the TT I need to set the dial at 8. This seems very strange to me. While listening to the TT I checked to make sure that both speakers were producing the same volume level and they were. Also there are some "Phono Level" pots on the amp. The owners manual states to but on a mono record set a volume level and then switch back and forth between the tuner and the TT. You are supposed to make the sound levels match. Needless to say I could not make the level match so the pots are cranked all the way. There is more hum while using the TT than other sources (tuner and CD via AUX). The Phono preamp section uses 12AX7's (same as the tone control amp). All the tubes tested good on Dave's (Mallet) tube tester several weeks ago. Since the 12AX7's are used in both the Tone Control Amp and the Voltage Amp and Phase Inverter circuits I figured that I could just move the tubes around to see if the problems followed the tubes. So here is my question (finally). If I move the suspect bad tubes to the tone control circuit or the voltage amp circuit and they are truly bad what should the outcome be? Also is it normal for phono input to be that much lower than the other inputs? Are there any other items that might be causing this? Other tubes in the unit are: 6AU6's for 1st and 2nd IF Amps and 1st and 2nd Limiters 6AQ8 for the RF Amp/OSC MIX One 12AX7 and 2 12AT7's in the tuner section 4 7591's for the power tubes EM84A for the famous Fisher Stereo tuning eye Again all tubes (except for the 7591's) were tested and tested good. The power tubes could not be tested on Dave's tester. Thanks for reading all this and please let me know if ya all have any suggestions. THANKS!! ------------------ ...wake up to find out that you are the eyes of the world... My Home Theater Page This message has been edited by eq_shadimar on 08-27-2002 at 10:04 AM Quote Link to comment Share on other sites More sharing options...
NOSValves Posted August 27, 2002 Share Posted August 27, 2002 If you switch the tubes from the phono section to the main gain section you should see less output from say the tuner or CD if indeed the tubes are the problem. I really don't think you will find that to be the culprit though. What all was in the kit for the phono section ?? I found with Scott amps that replacing every resistor with Quite Metal films on the entire phono section really sparked up the Output and quited down the phono hum ! I'm not at all familiar with Fisher stuff so there maybe some other cause here. One thing I know for sure I will be suprised if you ever get the outputs the same and if you do I think your LP expereince will suffer. Phono section never have equal gain or output compared to CD's and tuners. Craig Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted August 27, 2002 Share Posted August 27, 2002 NOS, what metal film resistors did you use? These can be really mediocre sounding compared to other options. I had some generic metal films in my EICO and all are gone now. Have you tried other options? kh Quote Link to comment Share on other sites More sharing options...
CaptnBob Posted August 27, 2002 Share Posted August 27, 2002 This may be obvious, but, on the off chance ... Make sure you're not plugged into (or switched to) a ceramic phono input. I've done this myself on occasion. Capt'n Bob Quote Link to comment Share on other sites More sharing options...
eq_shadimar Posted August 27, 2002 Author Share Posted August 27, 2002 The only mods made to the Phono section were the signal caps (coupling caps?) that go between PIN 1 on the 12AX7's and what looks to be the output of the RIAA circuit. The user manual states that it is cabable of handling both ceramic and magnetic cartridges but does not explain how to switch between them. I have a feeling that this is what the "Phono Level" pots are for (ie manual adjustment). If it would help I can scan in the schematic. As I said the unit will produce loud volumes levels via the Phono input. It just seems strange to be that with Klipsch speakers and a ~30 watt/channel amp that I would have to set the volume so much higher. Tonight I will try a different TT, a different input using a standalone phono pre-amp, and move the tubes around. Thanks for the input and keep the ideas coming! ------------------ ...wake up to find out that you are the eyes of the world... My Home Theater Page Quote Link to comment Share on other sites More sharing options...
NOSValves Posted August 27, 2002 Share Posted August 27, 2002 Mobile, From the response by Mike Lindsay I would say that the ones I'm using do a bang up job and there Xicons 1% tolerances cheap but seem to do the job !! Quote Link to comment Share on other sites More sharing options...
mike stehr Posted August 27, 2002 Share Posted August 27, 2002 I had some generic metal films in my EICO and all are gone now. You replaced them with Carbon comps, right? Metal films can be edgy in certain places, from what I understand. The resistors are just like any other parts, different types will make different sounds. Carbon comps are laid back as compared to Carbon films or Metal films, metal films would be brighter or edgy. I guess the Carbon films would be a little of both. I'm using Carbon film resistors because they were free. Eventually would like to get Carbon compisition resistors back in. (I liked the sound of them, but they were all drifted and crackly.) Sometimes a well placed metal film can help out a amp that's maybe too laid back. Hell, I don't know....... Xicon still makes cheap carbon comps. Carbon comps are pretty much lowest form on the resistor chain. But they sound nice with tubes, I geuss it just depends on how you want the unit to sound. Ramble. Quote Link to comment Share on other sites More sharing options...
eq_shadimar Posted August 28, 2002 Author Share Posted August 28, 2002 Just to follow up with my testing. As expected chaning out the tubes did not make a difference, however changing out the TT did make a difference. I also had the chance to run the unit for over 5 hours last night and everything is sounding much better. So all in all I am going to say problem solved for now. I need to look over the first TT and see if I can figure out what is going on with it. I would like fix the problem as I think it is the better of the two. i am saving up for a Music Hall entry level TT but it will be a bit before I get that. Thanks for all the replies! ------------------ ...wake up to find out that you are the eyes of the world... My Home Theater Page Quote Link to comment Share on other sites More sharing options...
NOSValves Posted September 1, 2002 Share Posted September 1, 2002 eq_shadimar Try getting a new needle or a completely new cartridge/needle combo. That is where all the difference is in the sound of a turntable also the arm needs to be setup properly its very important also. Craig Quote Link to comment Share on other sites More sharing options...
BBZink Posted September 28, 2014 Share Posted September 28, 2014 I found this only thread, but anyhow, here's my question: I have a fisher 500B, it has a bumpy ride in shipping, tube were crash in transport and wood case to, it is a few week, since i try to make it work, now it's seem to function after, I change all tube with modern one, till i'll find nos. But how do adjust phase inverter? if i have the front amp in front of me, should i turn clockwise to minimum or maximum output? Also, when in stereo on fm and the sound began to be distorted, should i adjust the blue knob on mpx? thank for any help you could provide? regards Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted September 28, 2014 Share Posted September 28, 2014 I found this only thread, but anyhow, here's my question: I have a fisher 500B, it has a bumpy ride in shipping, tube were crash in transport and wood case to, it is a few week, since i try to make it work, now it's seem to function after, I change all tube with modern one, till i'll find nos. But how do adjust phase inverter? if i have the front amp in front of me, should i turn clockwise to minimum or maximum output? Also, when in stereo on fm and the sound began to be distorted, should i adjust the blue knob on mpx? thank for any help you could provide? regards As far as adjusting the tuner section, don't even think about it! You need some fairly sophisticated test equipment to do this correctly, and it is very easy to mess up if it is not done properly. Regarding the phase inverter adjustment, there are a number of ways to do it (at the least you need a signal generator and oscilloscope). Here's one method which is about as good as any: https://groups.google.com/forum/#!topic/rec.audio.tubes/SBCBf0SOAKk And be extremely careful if you do anything under the chassis as the voltages there can be fatal!!! Maynard Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.