hurdy_gurdyman
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Posts posted by hurdy_gurdyman
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>i remember disco<
Personally, I'd rather forget it.
Dave [
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Good idea. Why didn't I think of that?
Dave[:$]
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Looking for opinions from a few different forums.I've been
happily listening to my TAD-60 amp driving the Silver Iris OB speakers
for a couple of months now. The amp came with used EL34 (Svetlana) tubes.
Running them 8-16 hours a day, it's just a matter of time before
needing replacements. The amp is set up to take EL34, KT88 and 6550
tubes (triode and ultra-linear mode.) I'm looking for opinions on which
way I should go. This is a bit of a major purchase for me these days,
so I could use some experienced guidance here. Things to consider
include longetivity under long hours of playing, non-fatiguing high
end, taunt bass and good midrange for acoustic instuments. I'll be
listening mostly in triode mode (unless one of the other tube types
proves to sound better in ultra-linear mode.) I listen mostly to jazz
and folk with some classic rock thrown in quite a bit.
Here's the amp I use.http://www.angelfire.com/biz/bizzyb/TAD-60.html
http://www.hawthorneaudio.com/drivers.htm
Here's the speaker drivers used (mounted on open baffles.)
Let's hear what you experienced tube rollers have discovered with amps that can do this type of conversion.
Thanks.
Dave -
I owned a 500C for over 15 years and used it off and on (along with various other vintage tubes and ss amps.) They are a nice sounding amp, but should never be considered good for bass. They have a very "warm" sound, even for a vintage amp. Modern good quality tube amps will leave them in the dust as far as bass goes. Many properly rebuilt vintage amps will, also. The 500C never had as good a transparency as some of the other amps I had, either. They did sound very nice and smooth in the right system, easy to listen to, but not representitive of what's available today with tubes. A really good tube amp can rock in the bass and everywhere else. You can't judge all tubes on one vintage tube receiver noted for being overly warm sounding.I love tubes, love using my tube tester and love watching tubes glow. I have restored a number of tube devices (antique radios and stuff). I also rebuilt a Fisher 500c and as good as it sounds (which is excellent), it is collecting dust in the basement. The bass is just too loose/thick with my Cornwalls. This quality may be desirable with Khorns or La Scalas, but not my CW's.
I'll take solid state with its tight, controlled bass. I like the high resolution, clean sound of solid state across the musical spectrum. Using The Fisher with my Cornwalls is like I am trying to make them sound like my ole Bozaks (which I do indeed like, but not as much as the CW's). I am going to sell that 500c at some point. It is a shame to let such a beauty collect dust.
Just my experience and honest opinion. I also understand that a well functioning 500c is not representative of all tube amplification.
Andy
Dave
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With all the discussions here of tubes vs SS, SET vs PP, etc, I thought some of you might like to read these papers. They are written a bit different than typical tech papers. I enjoyed them.
http://www.vaughnaudio.com/tech-papers.html
Dave
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Audiogon has some interesting threads about the TAD-60.
http://forum.audiogon.com/cgi-bin/fr_srch.pl?0&1&procsrch&3&4&
Dave
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I thought I'd add my 2 cents worth. You mentioned the TAD-60. I have had one of these for a couple of months now. These are a very modern sounding amp with lots of taunt bass and a silky-sweet treble. Mids are wonderful. Enough gain to use without a preamp. I like these far better than the vintage Heathkit, Scott, Fisher, Bell, Altec and harman-kardon amps I've had. I can't compare them with the other amps you mentioned (which, I'm sure, are fine amps), but I do know they are great amps in their own right.
http://www.angelfire.com/biz/bizzyb/TAD-60.html
Dave
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Larry,
Got it this time. I sent a reply.Dave
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Larry,
I've checked my email several times, but nothing from you yet. Perhaps you should re-send.
Dave
the_hurdy_gurdyman@yahoo.com
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I've decided to sell my Thorens TD-160. It's in good shape with only a few minor scuffs on the Plexiglas cover. One of the pins the cover hinges on is missing and has a small nail in it's place, otherwise looks good. No cartridge included. I can take pictures and send them via email. I package things well for shipping.
The reason for selling is that the TD-160 just doesn't do well on a springy floor. It's a well built table with a great reputation, but really needs a concrete floor or wall mounting. My floor is just way to springy for this table.
Price is $150 plus shipping.
If interested, send me an email.
the_hurdy_gurdyman@yahoo.comHere's a pic.
http://pg.photos.yahoo.com/ph/the_hurdy_gurdyman/detail?.dir=6d5d&.dnm=50c3.jpg&.src=ph
(The origional mat is being sold with the table, not the one in this picture.)
Dave
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Congratulations to both of you!
Dave
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Looks like I solved the heat problem. I cheated! I took one of those little pentium cooling fans (nice little ball bearing model) and hooked it up to a 6.5 VDC wal-wart (normally runs on 12 VDV.) The fan, which now runs very slow and quiet, is mounted next to the test sockets on top of the chassis, pointed diagonally toward the transformer (the side facing the 5AR4 rectifier tube.) There is barely any noticable airflow, but it's just enough to cause the two trannies to run at about the same temperature. It's beginning to look like it may have been heat from the rectifier and power transformer was causing the hot running of the right tranny.
The amp is sounding great and is not running hot enough to worry me anymore.
Thanks again Craig for your patience and help.
Dave
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Craig,
I found some instrutions on setting balance by hooking a wire to the right channel speaker output and plugging into left channel tuner input, remove right driver tube and adjust pot for minimum hum. Decided to try this with both channels and see if the heat lessens. I'll leave it on a few hours and see.
I'll be leaving this afternoon for a music fest and won't be back till Sunday evening. I'll post how the amp is doing before I leave, then check back in Monday morning.
Thanks for the help.
Dave
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Craig,
My hands are pretty soft these days, as I've been working as a luthier and musician for several years. Because of health issues, I don't even do a lot of either these days.
The only way I know how to balance for DC is with a VTVM or VOM by checking for any DC between the output pair grids. Chances are there is a better way, huh?
Dave
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Carig,
After several hours of running, the sound is still excellent, but that right tranny still gets way hotter than the left, uncomfortably hot. Maybe it's normal and I'm to much of a worry wort. While I was working on it earlier, I checked carefully the resistance of the right channel tranny vs the left one. They are identical, so no short. Wasn't able to find any more bad resistors. I put my hand on it for about 15 seconds then had to pull off as it was starting to hurt. I can leave my hand on the left on as long as I like.
Does this sound like normal extra heating from the rectifier?
Dave
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Sucess! Replacing the 68 ohm resitor fixed the problem. Turns out the resistor was in the negitive feedback circuit. Not a good place for an open resistor. Both channels sound identical now and I have the bias set right.
Dave
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>I for the life of me can't figure out why someone would tag on a bunch of resistors to correct a drifted value.<
One had already been corrected before I aquired the amp, so I simply played with a couple different resistors untill I got the other channel to have a 10 ohm reading. I didn't have any exact replacements on hand, anyway.
I may have found the main problem. I finally just sit down and started comparing resistance values between right and left channels until I found a substantial difference. There is a 68 ohm resistor connected to the coupling capacitor in the stage just before the final coupling cap. One of them (right channel the one running hottest) is open. Of course, I don't have that particular value on hand, so I'm going to check some local tv repair shops tomorrow and see what I can find.
Dave
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I can personally recommend either the AR-XA or Thorens TD-160 and TD-145. I prefer the AR by a small margin, but both make nice affordable tables. If you like to tinker, old Dual's can be spiffed up to work real nice, also. I have a 1019, and used to have a 1219. Both can be good sounding units, but usually require a good clean/lube to make everything right.
Any of these can sound much better than the slew of inexpensive Japanese tables that flooded the market in the 70's and 80's, or the less expensive Garrard's and all BSR's (of which there are millions...)
I'm using the AR-XA presently, and if you set them up carefully, they are far better than entry level. A real surprise to me.
Dave
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Craig,Dave,
So what your saying is each channel is running two 10 Ohm resistors in parallel this would equal having a single 5 ohm resistor. What these means is all the figures I have given you for having a single 10 Ohm resistor should be cut in half. So you are running the amp to hot. The max I would set the bias for each channel is .25V and in all reality with EL84 tubes I wouldn't run it over .22. I'm not sure where you got the information from but I would be very careful in the future.
The formula is pretty simple the 222D and LK48B should be biased at 44ma per pair of output tubes per Scott spec. so you take this figure
.044 x value of resistor = bias voltage setting
.044 x 5 = .22VDC for 5 ohm resistor value
.044 x 10 = .44VDC for a 10 ohm and so on.
*These above figures are for a pair of tubes*
The maximum idle plate dissipation of a EL84 is 12 watts to figure that you take the current the cathode is run at time the plate voltage
410V X .O44 = 18.04 /2 = 9.02 watts per tube.
You do not want to run the Max plate voltage way over spec and then also push the tube to its ragged edge on plate dissipation. The max suggested plate voltage of a EL84 is in the mid 300 range.
Craig
The two resistors on each side are not both 10 ohms. The one 10 ohm on each side measures about 12 ohms, so another resistor of higher value has been added (memory is telling me they are around 40 or 60 ohms) to bring the total resistor value of each side to 10 ohms. In effect, there is exactly 10 ohms measured for each pair of output tubes, which is as it should be.
Thje JJ EL84 tubes have performed flawlessly for over 10 months in this amp without even a hiccup.
I did a resistance check on both output trannies and each side measures the same, so at least I'm happy knowing that the trannies are ok. I'm sure the problem (less highs on the left) is a solvable problem, probably in the preamp section. Kind of sounds like a light blanket covering the left speaker.
I'm going to temporarily dig out my old Fisher 500C receiver and use it for a while until I figure out what I'm going to do with the Scott. What I really want is an old Heathkit AA-121. I like those old Heathkits, so maybe I'll watch for one and sell the Scott.
Anyone want a Scott LK-48-B? Needs a little work, but is fixable. No power supply hum to speak of and has new orange drops coupling caps. Would consider trade for Heathkit AA-151 or SA-2.
BTW, the Fisher is sounding pretty good right now, just a bit ugly to look at.
Dave
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Craig,
I worded my first post a bit wrong. There are four resistors, but they are in pairs, thus actually being one resistor per channel. The 10 ohm resistors have been bypassed with a second resistor (don't recall what they are at the moment) but they measure right at 10 ohms (or as close as my old Archer meter can tell.) As for the .3 volts, someone elsewhere told me to keep the voltage below .5 volts, and if the tranny felt to hot, to go below .4 volts. Again, my poor old meter is using it's 2.5 volt (analog) scale and may be off a bit. I was worried about the right channel tranny burning up, so I used a voltage on the lower side to be safe (maybe I'm paranoid, but I've lost 3 output trannies on various amps through the years, including a nice Stancor ultra-linear.) The tranny seems to run about the same temp anyway, so I'll increase it to about .45 and see what happens.
I went and re-soldered all the new caps (I replaced all the coupling caps in the amp and preamp.) I admittedly don't have much high frequency hearing anymore, but it sounds like the two channels are closer to sounding the same, but I need to listen at a time when I'm not so sleepy.
How can one tell if an output transformer is too hot? After running this for 12 hours or so I can place my hand on it, but it's awfully uncomfotable. Doesn't actually burn, though.
Dave
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Thanks for the info, Craig. I replaced all the coupling caps a while back with orange drops. I'll recheck the solder joints. In my opinion, the left "duller" sounding channel is the one that sounds wrong. The highs are just plain dull. I'll play with it for a couple of days, and if I can't fix it, maybe I'll call. I have a scope here.
Dave
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My trusty Scott LK-48-B has a problem. The right output tranny has been running a lot hotter than the left (never hot enough to burn flesh, but very uncomfortable after running all day.) The left tranny is only warm. I have checked volages. The tube plates all have 410 VDC, the cathode resistors have 0.3 VDC on them. All four resistors are exactly 10 ohms. No DC offset between tubes. Both sides appear to be identical.
Last night I did some serious comparing between the sound of the two channels. The right channel (hotter one) has much more prominant high frequencies than the left. I checked my EV LS-8 speakers with an old Sansui 8080 receiver I have and they sound identical to each other, so not a speaker problem. I'm using a quad set of JJ EL84's. I tried switching them with no difference.
I guess I need advice where to go from here. I have a couple pairs of trannies for 7591 tubes, but nothing for 7189/EL84 type tubes (if it turns out to be the trannie.) Don't know if they would make a decent substitute or not, but I suspect not.
What else can I check before giving up?
Dave :/
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The old Thorens TD-160 and TD-145 are hard to beat for the price. If you really want to try inexpensive first, consider an old AR table. The turntables are first rate, but the arms are rather primative. However, properly set up, they can do just fine. I like mine better than my TD-160. Old AR's can be picked up for under$50.
Dave
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Hmmm, I still didn't get the pic to come up on the page, only as an attachment. What am I doing wrong?
Dave
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Our friend Bob Crites is in the hospital.
in General Klipsch Info
Posted
Great to hear things are sounding promising. Get well soon, Bob, and best wishes.
Dave