mace Posted March 19, 2003 Share Posted March 19, 2003 Well, I've given my new (new to me) Scott 299 a listen for a few hours. At this point, all I can say is it is different than my SS offerings. I've been gone for about 10 days and I've just come home. The Scott awaited so I hooked it up right away. I haven't listened to my SS gear since I got home so I hesitate to compare since I know that 10 days away from the stereo can make it sound different when you get back (all mental). So, I'll give the tubes a while and go back to SS before final judgement. Plus, my CD source is beyond suck, which doesn't help anything. I have some questions: When I first turn it on and keep the volume at zero I can hear music through the B channel. (The A channel has nothing, as expected.) How does one fix this? The balance is way off. The A channel is about 6 dB louder than the B (measured at 50 cm in front of the squaker). This is very noticable at listening position. Is there some easy fix? I've adjusted the balance knob for now to bring down the A channel 6 dB, but now instead of a 30 W amp, I've got a 7 W amp. I don't consider this a long term fix. What does the "Rev Phase" switch do exactly? When I engage it, the B channel goes away completely. What is the ugly, unlabeled 1/4" jack doing on the upper right side of the front panel? Should I expect some hum (not hiss)? With the CD player stopped, there is a hum, a rather low one, which is audible. It doesn't get louder as I increase volume. The hum is noticable at the listening position, about 4 m from the speakers (Corns). Which setting is recommended: Volume or Loudness? More later! Pics coming soon. Mace Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 19, 2003 Share Posted March 19, 2003 Is this the amp you got from a Edster ?? sounds like something has went amiss somewhere along the line. You better check all your connections. I never heard the previous owner having a problem with it. You bought it without seeing a picture ? Craig Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 19, 2003 Share Posted March 19, 2003 Okay I just looked at Edster00 post and he said it worked excellant. So we have to trace down the problem. First off do you have the indepedence wires hooked up to select the 4, 8 or 16 ohm taps ? If so unhook them and tape them off and hook the positive speaker cable to 4, 8 or 16 ohm and the negative to zero (A is left and B is right). This will bypass the Phase switch which is a good idea anyway. Take all the tubes out and reseat them firmly in there socket. You need to bias this amp also so get with me and we will investigate what needs to be done there. Its been a year since I did this amp and at that time I wasn't keeping records so I have no idea if I modified the bias setup or not. I don't think I did but maybe. Did Ed ship it with the tubes in it or out ? If out did he label where they went ? If the volume pot plays real low out of one channel when turned all the way down its not a real big issue I've seen it a few times not much can be done with a 40 year old Pot but clean it or try to find a replacement. Now a 6db difference at normal listening levels sounds strange for a amp that worked excellant so something is goofy. What speakers are you using ? Also the amp shouldn't hiss if all is well unless its at near full volume. Also you should reverse the speakers. Hook up the right to the left and left to right does the volume difference follow the switch or stay in the same speaker ? Craig Quote Link to comment Share on other sites More sharing options...
MBM135 Posted March 20, 2003 Share Posted March 20, 2003 Mace, I'm also looking for a 299 and plan to enter the tube world. Can I ask what SS amp you are using now? MM Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted March 20, 2003 Share Posted March 20, 2003 Hey Craig Think 222C for a minute. on each speaker connection terminal strip there are two grounds. on the inside they're connected together. whassup widdat? Also, on the manual stuff I bought for the 222C it gives the procedure for the AC balance on the output stages. Sez to use a 16 ohm resistor on the speaker terminals, pull the driver tubes and measure voltage across the speaker connection. OK, I can do that, but which speaker terminals? 16? or does it even matter? Also, when testing for rated output, should a guy use 16 ohm R's on the 16 ohm terminals? or 8ohm on the 8 ohm terminals? or what? I tried this on mine older one, the one I put your caps in, I think I used the 16 ohm resistor on the 16 ohm terminals, but max output was exactly half, about 10W/channel. What's the right way to do this? Tom Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 20, 2003 Share Posted March 20, 2003 Tom, The 2 ground are for some wierd speaker setup from day's gone by you can use either for ground or Negative. I've never tested the output at the 16 Ohm taps all I have is 8 Ohm 50 watt resistors. I was under the impression that tube amp put out rated power to all taps. Are you sure you figure it right ? When did you get a finction/sound generator and a scope ? The Test your mentioning I would do on the taps you use with your speakers I would imagine your using 8 Ohm. I would love to know your results on the 8 ohm taps compared to the 16 ohm taps. I guess I could strap 2- 8 ohm together and check myself. I actaully hardly ever do that test anymore I rigged myself up a set of meters in a SS amp and checked them for accuracy and just use them for a reference its just quicker the setting it all up. It also makes it easy to check channel balance ! Craig Maybe Mark will read this and comment he is who I got the idea from. Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted March 20, 2003 Share Posted March 20, 2003 Craig, >>The 2 ground are for some wierd speaker setup from day's gone by you can use either for ground or Negative. That's kinda what I figured. My older not-as-nice 222C has real weak threads on the one of ground connections. I just looked inside, saw them connected, used the other. Worked. >> Are you sure you figure it right ? Not a bit sure. >>When did you get a finction/sound generator and a scope ? A friend gave his Knight Kit scope he built as part of he MSEE project back in the early sixties. It has very low hours and seems to work fine. It's got that cool gray wrinkle coat finish. The thing is really like new, just got a couple scratches sitting on his bench all these decades. I picked up a test CD set and have been using it for a tone generator. PITA so I bought a real nice Heathkit audio tone generator off ebay. It hasn't shown up yet so I'm still dinking around with the CD. Also picked up a real cherry Hickok 6000 from ebay. This thing is nice, not a scratch on it, even the red leatherette stuff on the outside is pretty good. I lifted the chassis, it's real nice underneath. I can't imagine sitting there in a Hickok factory and wiring those things. It's very neat and nice, well done. There's a big honkin tube under there. I need to find more tube data for it. the roll is really nice but is missing a lot of the popular audio stuff. Another member is supposed to be sending me a Variac. It's military surplus from Canada, he says it looks like it's never been used. Between that stuff and the Fluke I'm pretty well armed. Mu buddy that gave me the scope also has a totally cool vacuum tube voltmeter he built from a kit and a big old style Triplett meter that came out of the old Honeywell labs here in Phoenix when they shut down. I'm going to be hitting him up for one or the other, I don't like the "True RMS" AC deal on the new Fluke, it's a PITA, sometimes hunts around for awhile before settling down on a reading. I also picked up the digital output version of the RS SPL meter, it works real nice. It's got a bar graph display across the bottom that updates 5x/second. You can see the output of a CD player or whatnot. The resistor I found at Fry's is a 15 ohm, they didn't have a 16. This is easily compensated for in the math but I need to rig something up that's easier to use. What frequency would you test max output at? 1000Hz? White or pink noise? One thing I discovered with the SPL meter is that LaScalas really do die at 50Hz, mine are pretty flat down to there and fall off like a rock lower than that. Down over 10dB at 40. Tom EDIT: I did figure it wrong on the EICO. It put out 14V across the 15R. I = V/R = 14/15 = .93 amps. Power in watts = current x volts = .93 x 14 = 13 watts. Sounds pretty good to me, it was rated at 14W/channel when it was new. I'll have to re-do the Scott, I pooched that somewhere. Quote Link to comment Share on other sites More sharing options...
edster00 Posted March 20, 2003 Share Posted March 20, 2003 I didn't notice any of the problems Mace is experiencing, certainly not the balance problem. I didn't listen to it much though, as it was in my 3rd system. Perhaps something happened in shipment, but I packed that Scott very well IMHO. I believe that Craig told me the "ugly jack" is a headphone jack. Mace, If I remember correctly Craig said he would do the "bias mod" for you, if you are having that many issues with the Scott I would ask him to take a look at it and do the mod while he has it on his bench. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 20, 2003 Share Posted March 20, 2003 I bet we can figure it out if it was balnced and working fine then its something silly I'm sure you never know with the way they bang these things arround shipping. I had one not long ago a resistor actually fractured in shippng with out any other damage. If need be he can send it here and I'll be more than fair on getting it up toi snuff. But first lets see if we can figure it out thru here and on the phone so he can enjoy it some. Craig Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 20, 2003 Share Posted March 20, 2003 Mark, Thanks your much better at these technical explainations then me !! Craig Quote Link to comment Share on other sites More sharing options...
mace Posted March 20, 2003 Author Share Posted March 20, 2003 Thanks for the insights! To answer some of the questions: 1) The Scott is hooked up to the cornwalls, 1977 with some rope caulk on woofer bins. I'll do some flipping of speakers to A and B channels to track the problem. 2) I'm using the 4 ohm taps for the speakers. The "red" speaker wire goes to the 4 and the "black" wire goes to the "0" (zero). I am not aware of any "impedence wires" needing to be hooked up. This may be part of the problem?!? 3) Yep, I bought it without seeing a picture. I knew it was from a board member and that Craig went over it, so I didn't sweat it too much. From Ed's picture it looks great. It is just that on the inside it is cruddy in spots. I'll get it cleaned up later, no biggie. 4) The amp was shipped with the exposed tubes removed and bubble wrapped. The amp was double boxed. IMHO, the amp was packaged very well. Each removed tube was numbered and an easy to read schematic was included so I knew which tube went where. I'll reseat them and see if that makes a difference. The "protected" tubes were not removed. How does one remove the little cans to get at the tubes? Perhaps these need reseating?? 5) The amp doesn't hiss, but it does hum... this may be a grounding issue of some sort, or just normal for this amp. 6) I also received some hand writen notes and digital photos on how to bias the amp. At this point in time, I've no idea what biasing is, nor what the biasing mod is and how it affects the amp. I need to do some more investigating to understand these things. 7) My SS setup was an NAD 3240 (integrated amp) used as pre-amp and going to a B&K ST2140 power amp. 8) Please understand, I'm not implying I purchased a known screwed up amp. The reason I posted these questions here was for for future reference, should someone else have similar issues. 9) I do remember Craig's offer to give the amp a look over and check bias and what-not, as long as I paid shipping. I'm more inclined to learn such things myself so that I can take care of it in the future. We'll see how much is involved. 10) Was the headphone jack some mod (non-factory)?? Is it possible to disconnect it? 11) Yes, this was Edster's amp. Thanks for all the help! I'll do what was suggested and see what happens. Mace Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted March 20, 2003 Share Posted March 20, 2003 Mark, That's very informative, thanks for taking time to post. I can do the scope thing, but I don't have a distortion analyzer yet. I'll start digging around ebay, see what's out there. Know of anything for sale? I think I'll pick up an 8-ohm resistor set for this. Might as well check at the taps usually used. Your procedure is a little more detailed that I was doing. I just hooked up the R and cranked it full vol, measured volt drop across terminals. I'll try it with the scope as soon as the tone generator rolls in. The CD tone generator is a PITA, I'm always running out of track before I'm done. I've heard remarks in the past about the HF-81 trannies becoming saturated at well under rated output, I should be able to see this in the scope as the sine waveform deteriorates, right? Or not? Tom Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 20, 2003 Share Posted March 20, 2003 Mace, I finally remember your amp has the bias mod without test points !! Great. What you need to do is call me. Email me when you have time to do a little tweaking and we will fix this on the phone. You have your speakers hooked up right !! One thing I will warn you the last 3 people that complained about channel imbalance was all traced to the speakers themselves and the extra sound field and imaging made it more apparent then the previous amp. This is why I want you to switch them to see is it follows the channel. Email me and we will set something up to teach you the ropes craigostby@comcast.net Quote Link to comment Share on other sites More sharing options...
edster00 Posted March 20, 2003 Share Posted March 20, 2003 The hand written notes and photos on biasing were sent to me along with the amp when I got it back from Craig, that is why I included them with the amp. They should be very helpful when Craig talks to you on the phone. Quote Link to comment Share on other sites More sharing options...
mace Posted March 20, 2003 Author Share Posted March 20, 2003 Thanks! I may not be free until maybe next weekend to poke around in this thing. Is it OK to use the amp in it's current state in the meantime or should I not use it? Thanks again for the help, Mace Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 20, 2003 Share Posted March 20, 2003 Well it should be biased. You never know if the pot were bumped and moved from packing and un packing . If the bias it way off it could burn up a tube or worse yet a transformer. Craig Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted March 20, 2003 Share Posted March 20, 2003 Well, looks like I just became the proud owner of this HP 333A. I might have gotten one a little cheaper, but the seller reported this on as being very nice. Tom EDIT: here's a nicer pic: Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 20, 2003 Share Posted March 20, 2003 That is a nice unit and I think the price is right. I'm holding out for Marks equipment this summer ! I never buy cheap test equipment it just doesn't pay ! Where are you headed with all this looks like as I get to busy I could put you to work LOL !!! Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted March 20, 2003 Share Posted March 20, 2003 Craig, >> Where are you headed with all this.... I'm interested in this stuff, you've probably forgotten by now but several months back I floated the idea of producing an Eico clone with upgraded parts and marketing it as a kit or assembled. I'm still poking around the edges of this idea and need to be able to validate ckts and check stuff. I'm also interested in both 12AX7 and 6SN7 preamps, have looked at a couple designs. I took quite a bit of EE stuff when I was working on my (unfinished) MechE degree a few years ago, so I'm comfortable with some of the stuff I'm seeing, but there's always a big difference between book and lab knowledge and understanding how designers actually implemented things back in the 50's and 60's. I might be interested in some work after I get comfortable with the new stuff. I have a strong need to at least feel like I'm know what I'm doing before working on other people's stuff. Tom Quote Link to comment Share on other sites More sharing options...
mace Posted March 20, 2003 Author Share Posted March 20, 2003 Well, it's probably time to take this discussion offline since there are several other threads weaved in here (although that HP looks nice). First off: d'oh! * The imbalance problem was with the DVD player. I hooked up my PowerBook to the "tuner" channel and the balance was fine. I then hooked up the PB to "tape" and balance was fine. I then hooked up the DVD to "tuner" and balance was good. (I then remembered of an incident a long time ago, after I had the B&K for a few days, one channel was softer than the other. I thought it was the B&K. I turned the system off and on and the balance went back to normal. In retrospect, it appears the DVD was the culprit. It must be finicky about dis- and reconnecting to sources or something... who knows.. It is a cheap piece of crud but it does play all regions, PAL/NTSC and is macrovision free.) * With the volume set to zero, I get about 70 dB @ 1 m out of channel B (measured in front of squaker). Note: this is with both "tuner" and "tape" as source selector, using two different sources (PowerBook and DVD player). Tell me this ain't normal. * What is the V and L switch? * Now we be rockin'. Mace Quote Link to comment Share on other sites More sharing options...
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