TUBE BIAS, socket to me!

I'm biased toward tubes, both preamp and amp (and guitar amps of course) although my power amp is cathode biased needing no adjustment (single ended class A Pentode). I actually enjoyed biasing my previous tube power amp, even with the occasional mildly burnt finger.

OP, there is one thing for sure. You know it's done, BETTER than most because you did it.  That has always been my position..

Saying that, I have backed off a bit on the self imposed brain surgery (s).
YES practice makes perfect.. Any volunteers? I'm getting close, not seeing double anymore, or less..:-)

Happy Happy...

Regards

oldhvymec

It's hard to adjust bias with vision problems they tell me.

Is it really worth all this fuss? Can't you find a solid state amp that sounds as good or better, or are tubes less expensive for a given sound quality?

Don't shoot me - I am a vinyl guy, so certainly willing to go through some inconvenience for top SQ, but ever since I was in a room with tubes that got so hot a fan had to be installed (ruining the sound of the stereo), I never considered them.

I like to think I am open minded. Convince me why I should change my Plinius 8200MKII integrated amp to a tube one.

Sokogear, It's a personal decision based on your own listening to music. One cannot say for sure exactly which tube amplifier you might prefer to your Plinius SS one.  There are many types of tube amplifier, just as there are a few different standard topologies for SS.  You would have to put in the work yourself.  But since you have already stated your bias for SS, it might not be fruitful.  It's not anyone else's job to convince you of anything.

Thanks Lewm. I am hoping to hear from people who have tried or use both and their reasons for choosing tubes over SS. There was a similar discussion on analogue vs. digital and it was interesting to hear both sides opinions.

sokogear

Tubes can be a lot of fuss, IF you are a very fussy person, which I am not. Therefore, for 43 years they have been easy, and I have heard and prefer tubes over SS. Easy.

As I mentioned in the original post, I simply spray the controls, swish em around put em in the middle, listen. Never bothered with bias.

Make it easier on yourself. To avoid a lot of unknows, I bought, and advise buying a simple tube tester, which you might think fussy, but I like knowing rather than guessing the condition of existing and newly purchased tubes. I always do an annual pre-holiday tube check prior to Thanksgiving. Over the years, a few developed shorts, a few have died, a few have gotten weak. Easy to find and replace with a simple tester.

Over the years I have gotten away with original or substitute tubes 'of the same performance', probably why I have gotten away with plug and play.

This time, I changed types, 6550's to KT88's. It is recommended to change the bias when you change those in my amp.

I didn't bother, the difference is easy to hear, I prefer the KT88's.

Sooo, I asked: how important is bias really? If they sounded better, might they sound even better?

If I was buying a tube amp, I would prefer external bias, safer than needing to go inside mine, yet I am limited in choice by wanting 16 ohm taps on the transformer.

Elliot, I see no reason why you should be surprised that there are no products currently for sale that mimic your Macintosh MX 110, with an FM tuner built into a preamplifier essentially. FM radio is on the rocks. Not many audiophiles even try listening to FM radio for musical pleasure these days. Except maybe in their cars. Back in the heyday of the MX110, every major city had FM stations that actually competed with each other for the quality of their signal and prided themselves on their classical and jazz music content. That’s all gone, pretty much. So that accounts for the absence of a built-in tuner. As for the tone controls, those fell out of fashion in the 90s, except for some notable made in Japan preamplifiers from Accuphase and Luxman. Privately, I think they fell out of fashion because not incorporating tone controls saves a bit of cost on build and development. Audiophile publications often carried articles suggesting that tone controls add distortion, which of course they do. But it’s a question of trade-offs. As far as I am concerned, I would not consider a preamplifier with tone controls, unless they were switchable in and out of the circuit. Apparently you do enjoy FM radio broadcasts, in which case the MX 110 was made for your needs. It’s great that you like it so much. Now I think of it, Accuphase and maybe Luxman too may have made preamplifiers with built in tuners of more recent vintage than that of your Macintosh. Those would be all solid state, most likely.  Very  high quality.

lewm,

I don't recall indicating surprise modern preamps do not have FM. Few have them now, and anyone can stream FM online. I don't stream digital in my music system, and don't listen to FM in the home theater.

Many/most young people never heard excellent FM quality, including many of my audiophile friends. I'm old enough to remember when FM first appeared in cars, gradually replacing those AM radios.

I used to use Carver FM (another used find at Harvey's, amazing reception capability), and now only listen to 1 station, WBGO Jazz, my designated FM antenna in the attic pointed at their broadcast antenna. This FM is every bit as good as they say. Much more involving sound than the Carver (on a shelf, resale value about $15).

I used tone controls when in college, Fisher 200T receiver, and a pair of AR2x's. Also knew how to properly use Loudness Control, low volume while pulling many all-nighter's listening to Allison Steele, the Nightbird,  or Cousin Brucie while the wife and baby slept.

Now I have my L-pads on my speakers, I have never used tone controls since, however I would want them just in case.

I adjust balance, and benefit when a track needs it, prior to Chase Remote Balance it was a walk up, back, up, back, start the track over, PITA, in any case I always want balance. Using Mono Blocks, with individual manual volume pots on lower shelf was not fun. I used to run Onkyo CD with 2 sets outputs, 1 with volume control, direct to amp to speakers

I have had 'skip the controls' preamp and the current Cayin has 'preamp bypass', skipping it's volume control. I never hear a difference, always go for convenience.

Tone controls, filters, ... can get noisy, I am very good at getting to them and properly cleaning them to their original noise free state.

Yes, OK.

@elliottbnewcombjr - aren't all audiophiles by definition fussy? If you don't care about high SQ I doubt you would categorize yourself as an audiophile. You didn't say why you prefer tubes, if you ever had them in your system, when that was, etc.

Your description (testing tubes, spraying tubes, replacing tubes, etc.) sounds like more to do than I currently do with my amp, which is nothing other than leave it on all the time (after 15 years I hope I am not jinxing myself) except to turn it off when the cleaning lady visits, just out of paranoia, even though she knows not to touch anything in the stereo. I am scared she or one of her girls might bump into something by accident.

@sokogear

Is it really worth all this fuss? Can’t you find a solid state amp that sounds as good or better, or are tubes less expensive for a given sound quality?

my 2 cents

yes, no, and no

ymmv

@sokogear

You are defending SS, great. You ought to start a new thread about 'tubes are too fussy ...'.

I and many others prefer tube sound quality, I find tubes more involving. After many years, I sum it up as simply this: analog gets both the fundamentals and overtones 'right'. If you want to know what other people love about tubes, it ain't words, go listen. Many have listened, heard differences, and prefer SS. Many love inefficient speakers and need SS to get enough power.

That's it, except, you have implied I shouldn't consider myself an audiophile, because I am not fussy enough to achieve audiophile sound quality. 

I have achieved, with fun not fuss, over many years, excellent sound quality. Primarily from Vintage gear. I believe, if you came here you would love the sound of my system. I've had excellent SS gear here.

Let's be clear, fussy people enjoy being fussy, it's part of their enjoyment.

Yes tubes are more fussy than SS. I am trying to tell you, if you hear and want tubes, don't fear, tubes don't need to be too fussy.

And, if you are tempted by tubes after hearing them, I believe any person with tube gear: owning a simple tube tester is part of having confidence with tubes. 

If you leave your SS on all the time, IMO you 'drank the koolaid'.

Tubes need break in when new, say 60 hours, after that, me: on just a few minutes before use.

I don't spray tubes, I spray the controls, moving parts with electrical contacts within vintage equipment using contact cleaner and lubricant. That's inherent with vintage equipment, not fussy, regular maintenance. SS doesn't need maintenance? I had to clean the controls of my McIntosh SS Preamp and SS Amp. Newer stuff, perhaps not.

Take great vintage stuff apart, see the thin wires, the 'good enough' parts, nowhere near the current 'audiophile' quality parts, yet those wires and parts is what made that company's reputation.

I'm not criticizing others, but for myself: What I hear: the difference between speakers, between the interaction of the space with those speakers. And excellent engineering of source material. Better TT (up to a point), cartridges.

I hear the difference between formats, LP and Tape, higher noise specs, surprising to many, always besting CD here, and Tubes always preferred to SS when compared here. 

Other than that, I'd rather buy more music than chase minute improvements, fussy improvements if you will.

I have a dedicated circuit for my preamp and amp. Everything else, CD, R2R, Cassette, 8 Track my Chase unit on a regular household circuit. Only one source device is on at a time.

NO: power conditioners, monster power cords, super fuses, directional interconnects, pure silver ... contact fluid on rca jacks, source equipment with external power supplies, weights on my cd player, bejeweled speaker cables, or trusses off the floor. 

Just 'good enough' quality equipment, via tubes to with very revealing  speakers luckily in a listening space great for them. 

I have a good friend with all of the above. He loves my system. We have brought much of his stuff over here, bit by bit, he has to admit, we don't hear a difference. I watch him search for 'better' for many years, frankly he needs a better space, and his speakers are terrific but too narrow dispersion and lack bass. Fixed on spikes (that I gave him), terrific imaging only for center spot. Minimum controls, minimum interconnects, no tone controls, ....

Once, only once that I remember, way back when, a group of golden eared reviewers finally agreed to a blind listening test. Between a Pioneer Receiver and high end separates, the 'best' of the day. Statistically, the answers were random, no discernable difference could be identified.

Once I got an interesting woofer at a garage sale, holes and tears in the cone. Just for fun I slapped some scotch tape on it, it sounded surprisingly good. Finally learned Einstein's theory of relativity.

You may have learned A theory of relativity, but it has nothing to do with Einstein's Theory.

Couldn't have been, it was easy to understand!

@elliottbnewcombjr- I’m not defending SS- its all I’ve ever used. The stereo dealer I trust most told me it depends on the amp more than the technology. Tubes tend to cost a bit more for a given SQ. As I said, my only experience was listening to tubes when the room heated up significantly. Just like belt vs. direct drive TTS - it depends on the table.

I think you are fussy, and an audiophile. My wife and kids think I’m nuts, but I think I am practical and believe in the law of diminishing returns. I’m not an upgraditis guy spending 10’s of thousands on a whim for the latest and greatest. I didn’t get a record cleaning machine because my records are in perfect shape (mostly) and when a dealer had me bring some records in and compare the sound before and after cleaning, I couldn’t hear a difference. I don’t buy old used records unless they are NM or unopened.

Since I leave my amp on all the time I’ve drank  the kool-aid? What does that mean?

I do use a power conditioner- things have to be plugged in somewhere, right? Got a good Furman one used for $300. No dedicated circuits, but I don’t think there are any things being used on the circuit except my amp, phono stage, turntable, tv, and cable box.

I recently vastly improved my turntable by first putting an isolation platform under it. I was convinced by a frequent AG contributor (MC) who swore by it. I was very skeptical about that tweak, but it made a dramatic improvement, like a new turntable - more detail, depth, bass, and to remove foot faults because of my suspended floor over a crawl space put a wall shelf in for my turntable. Of course foot faults went away and the sound improvement was subtle if anything. 
My one interconnect was $200, power cords were all about $100, and my speaker cables were about $500.

No other tweaks other than Herbie’s tenderfeet under my amp and phono stage ($100 total). That was a more theoretical improvement purchase as keeping wires perfectly still does improve the sound, but the question is, can you hear it? Probably not.
My speaker sensitivity is 88dB, so maybe I shouldn’t consider tubes. MC says not to buy speakers under 92dB. I think he goes overboard sometimes.

You hit the nail on the head though, so much is dictated by the room. 
I am thinking that if I follow my rule of not doing any component upgrade unless it is a NOTICEABLE improvement and under $1K net after trade, so I’ll probably stick with my Pliniuis.

i don’t know how old you are, but I think some people who grew up with tubes prefer them. I grew up with vinyl, built a nice collection and tried CDs and didn’t think they even came close to records.

Einstein's Theory of Audio Relativity:
Sound quality equals double blind BS times the vintage age squared.

Auto biasing amps, worth every penny!

Vintage, classic, antique or old, heavily used, low tech, rebuilt? The words you show your bias.

New, high tech, modern or unproven, bleeding edge, trendy? Same thing.

I can’t stand the Marketing BS.

vegasears

Auto biasing amps, worth every penny!

I wish my Cayin had it, alas, adjusters within.

I got hooked on the reviews of the Cayin, they have auto-bias on mark 2,3 but my speakers are 16 ohm, only mark 1 has 16 ohm and it’s bias controls are inside.

Seller had it biased just prior to sale to me, however that was for it’s 6550’s. I tried KT88’s for the first time, much prefer them, and .... of course I should bias them. I’m a DIY, but the words ’lethal’ ’death’ ... gave me lockstep.

Made myself a nice long screwdriver out of a hardwood chopstick, dusted off 30 year old multimeter: new batteries, clean moving parts, pots, contacts, then realized, I never used this multimeter, I don’t understand this stuff. I even found it’s 30 year old manual in my ’instructions’ folder in the basement.

I feel I’m all dressed up, nowhere to go.

jss491,799 posts12-27-2020 12:08pmhttps://forums.stevehoffman.tv/threads/tube-integrated-with-autobias-equivalent-to-cayin-a88t.784890...

if you haven't seen this elliott - some interesting background and discussions

Thanks, I am going back thru the discussion, reminding myself of the many suggestions, and took the time to go thru that, it is interesting.

oldhvymec1,917 posts12-28-2020 6:36pmhttps://www.pinoydvd.com/index.php?topic=139769.0

OP check this thread out pretty good, pics in all...

...........................


thanks, finally had a look today.

Preamp Connected???


"amp should be connected to your preamp but volume is turned fully down ( NO signal applied to the amp )."  


 jomar

• 
  

Re: Cayin A88t - Biasing

I owned previously a A88T amp below are the biasing procedures. Please take note that the amp has HIGH voltages thus extra care should be taken.

1. Open bottom cover to have an access on the Test Point ( TP ) and Variable Trim pots (VR) .
2. Speakers should be connected and amp should be connected to your preamp but volume is turned fully down ( NO signal applied to the amp ).
3. Turn-ON power amp for about 10 minutes to warm-up tubes.
4. Attached positive ( Red ) probe of DVM (Digital Volt Meter) to Test Point . Negative probe of DVM to GROUND.
4. Adjust the VR which corresponds to the tube being biased to get 0.4Volts (400mV) reading
    *** VR1 for V5 , VR2 for V6, VR3 for V7 and VR4 for V8
5. Verify reading after 30 mins to finetune .
6. Power OFF amp and put back bottom cover

lewm

now I see what you were referring to re 'surprised'. but this was a quote found and pasted by another poster, not me.  

"Like me, after living with the MX110Z for a while, you may wonder why all modern preamplifiers don’t include FM tuners and equalization controls—they’re great fun! Also, tell me, is there anything even remotely comparable to the vacuum tubed McIntosh MX110Z currently available today at any price? No, which is a pity."

Price: I don't know when that was written, I got lucky, the mx110z has increased in price over the last year.

A tube tuner/preamp with tuner and phono only would be cool, no need for so many inputs as the integrated amps have them. Gotta have remote volume and remote balance on the integrated so that's available to all sources. 

In my long experience, tube amplifiers that require periodic bias adjustment typically provide both external test points (female jacks where you stick the pos and neg meter probes) and externally accessible potentiometers with which to do the bias adjustment.   Some owners of ARC amplifiers have already mentioned this. Some brands (like Atma-sphere on at least some of the model line) even provide a built in external meter, so you don't need to own a DVM, etc, in order to adjust bias. Another large set of tube amplifiers have an autobias circuit built in, which automatically senses a drift in grid bias voltage and compensates for it, until the tubes themselves are worn out.  Your Cayin amplifiers are unusual in that they apparently do require manual adjustment of bias, but you seem to have to open up the chassis to get at the adjustments.  That may reflect their "made in China" provenance, where perhaps the liability laws that provide legal recourse for persons who are injured by electrical shock whilst biasing are less stringent.  (But perhaps the US distributor could be made liable in the US.) So just take the warnings seriously and proceed carefully.  I always keep one hand in my pocket when working with power on, to remind myself never to grip the amplifier with two hands, which could send a shock across your heart muscle.  It doesn't take much to be lethal.  I don't think you need a non-conductive screw drive blade so long as the handle is non-conductive.  But it couldn't hurt.

Maybe Ralph can chime in, but I have no idea what is being adjusted to 0.4V in your amplifiers.  Surely that does not represent grid bias voltage (between grid and ground or grid and cathode) for an output tube.  Perhaps you are adjusting the voltage across a fixed value resistor which in turn affects bias current.  Also, you need a fairly good quality meter to be accurate in that under 1VDC range.

Now your talking electrocution precautions? Come on.... it can’t be worth it.

i guess as a physics lab hobby, its OK- I’d rather listen to music than play in the lab with tubes. 
I had physics lab in college 40 years ago. No desire to go back there.

@elliottbnewcombjr Before the owning my VTL 450's I had VTL 300 Deluxe mono blocks and they were not Auto Biasing so I feel your pain!

Soko, Read what I wrote.  Elliot's Cayin amplifier is the only tube amplifier I ever heard of where the manufacturer actually invites the user to enter inside the chassis, under any circumstances, let alone when powered up.  All other (US-made) tube amplifiers I know about will usually carry a warning NOT to open the chassis, ever.  Usually the warranty is voided if one does that.  Typical tube amplifiers can be re-biased externally with no risk, or not at all if they incorporate an autobias circuit.  Got that?
It so happens I am a DIYer, so I often do work on my amplifiers and preamplifiers, usually for fun and to satisfy my interest in electronics.  But I didn't even try to do that until I had a solid knowledge base, in part to keep me safe.

Gotcha @lewm. So what user involvement would be involved with normal routine maintenance/upkeep of tube equipment of 2000 vintage or later? Testing, rolling, cleaning, biasing, replacing, etc.

For analogue, I have to get a new stylus (or cartridge) every 2-2500 hours of use.Maybe change a belt after 10 years. I’m not aware of direct drive tables needing anything.

vegasears1,073 posts01-10-2021 2:01pm
not Auto Biasing so I feel your pain!

Not feeling pain is what this is all about!!!

If one wants to roll tubes, one can do so, but that is not a requirement.  To me, it is a form  of mental masturbation.  Bias adjustment would be per the suggestion of the manufacturer.  Some designs run the tubes harder than other designs (closer to their maxima for voltage and current).  Such designs would benefit from bias adjustment at more frequent intervals compared to designs that run the tubes conservatively, because the tubes are wearing out faster in the former case.  How often to replace tubes is also design-dependent.  Vinyl is much more demanding than using a tube amplifier, on a day to day basis, IMO.

Thanks @lewm. You didn't mention about tube testing - how often? I did think tube rolling was kind of just fooling/playing around, especially with newer tube amps.

Day to day, of course, brushing the records and getting up to flip them every 20 minutes (or 10 with 45's) and handling the records (dealing with the sleeves, jackets and external sleeves and filing and removing them) is more time consuming than CDs, let alone streaming, but at this point, it is kind of a ritual.

Do all tubes heat up the room, or is that a design function as well, the harder they run?

Lastly, I have a SS phono stage. Does this reduce the potential benefit of an integrated tube amp? I got this about 9 months ago as before I used one in my integrated that was only adjustable between MM and MC with no variation on load or gain.I never knew how much better my system would sound with a dedicated phono stage versus the one that came with my amp.

When I bought it, the cost of tube phono stages was substantially higher than SS ones, and I was told the lower cost tube ones were "noisy". Is this the case with integrated amps as well?

Just doing some longer term planning/thinking.

Thanks for your opinion.

The amplifier itself is the best tube-tester.  If a tube fails to bias correctly in situ in the amplifier, it should be replaced.
Unless you want to spend thousands of bucks on a separate tube tester that can actually test power tubes at their typical voltage and current, you don't need a tube tester at all.  This was mentioned earlier.  The vintage tube testers, many of which are collected by strange people who collect tube testers, were generally NOT able to test power tubes at meaningful levels of voltage and current.  Of those vintage testers, Hickok is the brand worth having, because Hickok testers along with only a few other brands can test transconductance.  Testers ARE nice to have around for small signal tubes, used in the front end of amplifiers and in preamplifiers/phono stages. But even that is a bit frivolous.  I do own a Hickok Model 533A, one of the older models probably from the post-WW2 era. I do use it to check transconductance (Gm), which is a sign of the life stage of a tube.  If Gm is below the accepted range for that tube, you can ditch it with a clear conscience. I paid $75 for the 533A.  The grandson of the 533 is the 539, one of the most sought after.  A fully reconditioned 539 in top operating condition will cost you more than $1000, easy.  539s come a little closer to being able to test power tubes properly but not really close enough.  I would bet almost no one here besides me owns any tube tester.  I bought it for my own interest in DIY.

@lewm - what about my other questions?

@lewn,

The statement below was from a positive feedback article about the MX110Z that Elliot was gracious enough to provide us.

"Like me, after living with the MX110Z for a while, you may wonder why all modern preamplifiers don’t include FM tuners and equalization controls—they’re great fun! Also, tell me, is there anything even remotely comparable to the vacuum tubed McIntosh MX110Z currently available today at any price? No, which is a pity."

http://www.positive-feedback.com/Issue77/vintage_mcintosh_experience.htm

@ elliottbnewcombjr,

Talk about a labor of love and patience! You kept the same preamp and kept it working after all these years. The money you've saved and knowledge gained on that unit, from not having that dreaded disease of upgraditis...Bloody brilliant if you ask me. 

As an Architect, whose path went the way commercial interior designer. I'd love to hear some of your stories on acoustics where the materials used were passive and maybe active in a room/hall you designed with the customers acoustic wants in mind. 

tyray

I just bought that used McIntosh mx110z tube tuner/preamp in June 2019, a purchase of love but not a long held piece. I sold my McIntosh SS Preamp C28 and McIntosh SS2250 to switch back to tubes.

I have avoided upgrades fairly well, primarily because I have been lucky to both inherit great stuff and been given some great stuff. I have given a lot of stuff to others as well. Met Bill here last year, we swapped my Fisher 800C receiver for his Mitsubishi Vertical TT, LT-5V which I revived and plays in my office system now.

I designed Corporate Offices, New Headquarters, Relocations, Renovations, for 47 years: NYC, Phila, Wash DC, Chicago, San Fran, Toronto, hired my own consultants, did everything soup to nuts.

Just go buy a Raven and put that biasing crap to bed.

skypunk

you haven't been paying full attention, I need 16 ohm taps, the only Cayin with 16 ohms is the original version, with internal bias adjusters.

Raven looks nice, but no 16 ohm taps

@elliotbnewcombjr.I never pay attention and that your loss needing 16 ohms.

like I said buy a raven they make speakers too!

skypunk

I would like to hear a Raven tube amp. Do you live near central NJ?

Trust me, the sound of my 16 ohm speakers is no loss.

And, there is less distortion from an amp’s 16 ohm tap.

https://forum.audiogon.com/discussions/16-ohm-speakers-any-amp-sounds-better-with-more-resolution-sp...

tvad

thanks for the link, that fine looking unit came up in this related thread

https://forum.audiogon.com/discussions/16-ohm-speakers-any-amp-sounds-better-with-more-resolution-sp...

I'm gonna stick with this amp, and have Steve from VAS do it while I watch, then I will use my long wooden screwdriver and do it myself.

Evidently my very old Multi-meter is a good bit less accurate than a digital one, so I will get one of them.

The amp sounds awesome, I just wanted to learn how important people thought proper Bias was. As always I have gotten a lot of help here and learned a lot.