Hi,

I am currently using an ARC REF110 in my system and had a couple of questions on it:

1. How often do I need to bias the amp?

2. Would it be a good idea to tube roll with this amp? If so which ones input or output?

3. Normally after how many hours of use the amp need to re-tubed?

Sincerely,
-dollarman

I usually adjust the bias at least once per month with my Lamm ML 2.1's

When I had ARC Ref 600 Mk lll I readjusted every listening session as there were 31 tubes per amp,

Tube rolling is always fun. Typically ARC uses 6550C's and better results in the midrange can be achieved with KT88's or Sovtek tubes

The golden rule with changing tubes is "when the system stops sounding right or somewhat muddied"

Another consideration is to change the tubes when you can see through the silver barrier at the top of the tube. BTW, don't ever just change one but rather all at once

Not sure if your amp uses 12ax7's which if so that is the single tube to roll to achieve dramatic results as this is the tube that the signal first sees. I use Telefunken NOS circa 1962 12ax7 and the effect is wonderful.

Mullard 12ax7 is also one to consider circa 1957.

Hi OB,

Thanks for your input. The REF110 uses 6H30s in the input stage so probably can't do any tube rolling here. I will check the KT88s but I read on another thread that the downside of using KT88s is softer/loose bass. Has that been your experience with these?

The REF110 uses 6 tubes per channel so biasing once a month should be ok I guess.

Sincerely,
-dollarman

You are correct. The KT88 offers wonderful midrange but at the expense of the lower end

Stick with the 6550's

You are correct. The KT88 offers wonderful midrange but at the expense of the lower end

Stick with the 6550's
Yup. KT88's are richer, bloomier. 6550's are more dynamic and quicker with more punch.

Of the currently available 6550's that are reasonably priced (i.e. not looking for NOS etc.)
A lot of people seem to be liking the Electro Harmonix for their rich midrange, they are really on the KT88 side and a bit warm for my tastes.
I've been using the Svetlana because they are a really exciting dynamic output tube.
The Sovtek is even less polite than the Svetlana.
Never tried the TungSol in my system.

You will get a sense after awhile of how quickly your amp gets out of bias and how quickly your tubes wear. Unless you find someone that has the same amp as you and puts a similar number of hours and on/off cycles, any specific advice will be little help to you. I do however find, that I replace output tubes about twice as often as I replace input tubes.

most amps are self-biasing these days. still unsure why ARC isn't actually.

KR

most amps are self-biasing these days. still unsure why ARC isn't actually.

KR

I disagree with you Keith

Hi,

I am currently using an ARC REF110 in my system and had a couple of questions on it:

1. How often do I need to bias the amp?

2. Would it be a good idea to tube roll with this amp? If so which ones input or output?

3. Normally after how many hours of use the amp need to re-tubed?

Sincerely,
-dollarman


I would assume that your ARC manual says something like 2000 hours for the output tubes and 5000 hours for the 6H30s. While the output tubes might run longer, if you run one to failure, you'll probably have to replace some components.

I'm betting that the ARC 6550s are probably the best all-around performers; ARC can afford to put in whatever they want, and they listen very carefully to their products.

I have a VT-100iii (with a Ref3 and an MP1 and a few 150.2s - yes, I am an ARC freak), which is generally similar to the 110. I hear the 110 has some new caps and other features and sounds really good. What do you think about the sound?

Thanks for the responses so far. One good thing about ARC is that if there is a tube failure you can give them the tube number and they can send you an exact replacement for that one tube.

Biasing is maybe something which I have to experiment with to see how often that needs to be done. As I am still running on the demo unit I don't have the owner's manual which might have some guidelines as to tube hours and how often biasing is necessary.

As far as sound is concerned I am quiet happy with the amp. However I am not an audiophile and I have not played with that many amps (tube or otherwise) over a couple of decades to make any meaningful comparisions to other similarly priced products.

With my current set up I am trying to follow OB's advice of taking the time to smell the roses rather than falling into the eternal spiral of upgrades.

Sincerely,
-dollarman

As far as sound is concerned I am quiet happy with the amp. However I am not an audiophile

your gear would suggest otherwise.

Happy listening

With my current set up I am trying to follow OB's advice of taking the time to smell the roses rather than falling into the eternal spiral of upgrades.


That sounds like a great plan. That amp will last you at least a decade.

I disagree with you Keith

well, BAT, Cary, VTL, Vac all basically are. i believe the new CJ stuff is too.

some of the lower priced stuff (under 2k) may need biasing---but any amp over 10k these days i would think otherwise.

put it this way--for you to have to re-bias as often as you did to me is ludicrous on a 40k retail amp!

now, biasing a single ended Lamm is not very complicated and probably quite fun! however, biasing an old ARC VT100 tube by tube is no fun.

Hi,

I am currently using an ARC REF110 in my system and had a couple of questions on it:

1. How often do I need to bias the amp?

2. Would it be a good idea to tube roll with this amp? If so which ones input or output?

3. Normally after how many hours of use the amp need to re-tubed?

Sincerely,
-dollarman

for #2: i wouldn't bother rolling output tubes, but sometimes the input tubes are fun. i did that with my Carys and it really was a phenomenal improvement when i put some Siemens in...

i also think tube rolling in preamps is more dramatic than power amps (couldn't explain to you why however)

now, biasing a single ended Lamm is not very complicated and probably quite fun! however, biasing an old ARC VT100 tube by tube is no fun.

It is fun

I agree with you completely

Biasing the Ref 600 Mk lll was a pain in the a$$. It took forever

Keith, when will you be up this way again?

well, BAT, Cary, VTL, Vac all basically are. i believe the new CJ stuff is too.

some of the lower priced stuff (under 2k) may need biasing---but any amp over 10k these days i would think otherwise.

put it this way--for you to have to re-bias as often as you did to me is ludicrous on a 40k retail amp!

now, biasing a single ended Lamm is not very complicated and probably quite fun! however, biasing an old ARC VT100 tube by tube is no fun.Any circuitry required for auto biasing is just more stuff hanging off the power supply and more that must be isolated from the audio circuit. Anything that potentially damages sound quality is generally frowned upon when spending that kind of scratch.

Any circuitry required for auto biasing is just more stuff hanging off the power supply and more that must be isolated from the audio circuit. Anything that potentially damages sound quality is generally frowned upon when spending that kind of scratch.


Precisely my point when I said to Keith "I disagree with you".

Hi
Love tubes but because of logistics, staying out of tubes and somehow being extremely contempt with the end of the endless bias-checking and the tube changing and the sound changing because the original tubes were NOS but the replacements are of a different vintage, etc... Yet tubes provide something that SS, so far do not (and vice versa , i must quickly add)

I beg to disagree with both Harrypt and OB.. From a design standpoint the self-biasing provides the optimum biasing level for the tubes at any time, it does not take much from the power supply, besides at that level of price providing the few milliamps required by a self-biasing circuit does not add much to the cost of material or the complexity of the design.. On the Lamm there is really no need for it, since the tubes complement is so sparse but on a REF 600.. it is a necessity so as to extract the best from the amp...

Any circuitry required for auto biasing is just more stuff hanging off the power supply and more that must be isolated from the audio circuit. Anything that potentially damages sound quality is generally frowned upon when spending that kind of scratch.

just like the fancy displays on the new ARC amps (and others), eh? give me a break. call Kevin Hayes, Luke Manley, or Victor Khomenko and ask.

in fact, i would disagree to state that the tubes being properly biased all the time allows for potentially BETTER sound.




OB- i am planning a trip in Sept/Oct. definitely need to have a listening session (or two!)

just like the fancy displays on the new ARC amps (and others), eh? give me a break. call Kevin Hayes, Luke Manley, or Victor Khomenko and ask.

in fact, i would disagree to state that the tubes being properly biased all the time allows for potentially BETTER sound.




OB- i am planning a trip in Sept/Oct. definitely need to have a listening session (or two!)

Looking forward to it Keith

in fact, i would disagree to state that the tubes being properly biased all the time allows for potentially BETTER sound.



Maybe I'm misreading your sentence, but how so? How/why would an improperly biased amp sound better than one that is correctly set?

in fact, i would disagree to state that the tubes being properly biased all the time allows for potentially BETTER sound.



Improperly biased tubes/transistors would allow excursions into operating areas with distortion, which is not what you want. The music may sound different, but it is certainly not a true reproduction of the original signal. :confused:

Improperly biased tubes/transistors would allow excursions into operating areas with distortion, which is not what you want. The music may sound different, but it is certainly not a true reproduction of the original signal. :confused:

I agree completely.

Knowing Keith I will have to ask him what he meant by that the next time that I see him.

Maybe I'm misreading your sentence, but how so? How/why would an improperly biased amp sound better than one that is correctly set?

sorry Curt- wording came out funny---i was talking about a properly biased amp sounding better.

Thanks for the responses so far. One good thing about ARC is that if there is a tube failure you can give them the tube number and they can send you an exact replacement for that one tube.



While that is true, what they can't take into account is whatever wear has taken place between the matching process that occurred at the factory, and the time of tube failure in your installation. Their matching may be useful should you pop a tube in the first month or so, but after a few hundred hours of listening, I'd be leary of just replacing one. I'm sure the amp would work, but I doubt if it would provide the sonics you desire.

Whenever I have a tube failure, I always replace the entire channel's worth of output tubes. (and note, I state when, not if - I'm running a dozen matched EL34s - I have the option of those or 5881s, and while the EL34s are nowhere near as reliable, I much prefer the sound.)

Rene - dunno about the KT88s - while I have used a number of them, and have a couple NOS ones from the 60s, at least the ones I have are less than spectacular. Fun to think of, but possibly not as fun when you actually get to hear them...

Whenever I have a tube failure, I always replace the entire channel's worth of output tubes. (and note, I state when, not if - I'm running a dozen matched EL34s - I have the option of those or 5881s, and while the EL34s are nowhere near as reliable, I much prefer the sound.)

I agree. I never change only one tube

Rene - dunno about the KT88s - while I have used a number of them, and have a couple NOS ones from the 60s, at least the ones I have are less than spectacular. Fun to think of, but possibly not as fun when you actually get to hear them

Here I have to disagree. I think the KT88 is a very warm tube without much of the bottom end that the 6550C provides.

I've been running a VT-100mkiii for several years w/no problems. I plan to replace the output tubes at 2500 hours or so, but if I have a tube "failure" (I don't know how they normally "fail"), will it likely damage other components (e.g., a resistor)?

I have not got any long experience with tube amps but the only failure I saw was when my dealer brought the 110 from Germany without removing the tubes what as far as I know is a big no no. I did not notice the tube failure but the amp sounded edgy and strained specially at higher volumes.

I reported this to the dealer and he asked me to check the tubes and I spotted out straight away that one of output tubes had gone white. I got a replacement from ARC in 3-4 days which is excellent keeping in view that it came from States. Since than I have had no issues with the amp.

My dealer has assured me as well that as long as the amp is not moved frequently with the tubes plugged in blown tubes are a rare incident. For my sake I hope he is right.

No need to change every 2500 hours. Those tubes easily will go 5000 and perhaps even 10000 hours.

Best time to change is when the sound appears muddied.

Some people will change all tubes once/year regardless

I've been running a VT-100mkiii for several years w/no problems. I plan to replace the output tubes at 2500 hours or so, but if I have a tube "failure" (I don't know how they normally "fail"), will it likely damage other components (e.g., a resistor)?

You'll know when one "fails." :) In my experience, usually an internal short(?) which usually takes out a few resisters inside the box. Worst part is the cleaning out of burnt resistor debris, plus the smell.

2500 hours - OMG :eek: - whatever works for you. 500 is usually enough for me, 1000 max. But admittedly, a lot depends upon the amp, its design, and how hard it is actually pushing/working the tubes. I am NOT familiar with the amps you are mentioning - mayhaps the power tubes are all but idling, in which case you won't have blowouts, and you can run them for indecently long periods of time. In the rigs I run, plate voltages are sufficiently high that EL34s do pop, and I lose the glassy, open high end that I want way too soon.

oneobgyn - didn't mean to argue - glad the 88s work for you. I really wanted them to work for me. In my case, I just didn't like the results. But I'm still looking for a nice set of KT66s. :p Probably won't like them either, but one never knows - that's half the fun.

No need to change every 2500 hours. Those tubes easily will go 5000 and perhaps even 10000 hours.

Best time to change is when the sound appears muddied.

Some people will change all tubes once/year regardless
I find that muddiness progresses so slowly that I don't notice the first 60-70% of life is gone. I once waited until the tubes were really gone and realized that I'd been listening for a while with the sound greatly deteriorated. For this reason I just do an output tube swap as one of my chores each Spring along with checking the smoke detectors and changing the oil. I also buy two sets so that I have one spare set on the shelf just in case. Never be without music!

I find that muddiness progresses so slowly that I don't notice the first 60-70% of life is gone. I once waited until the tubes were really gone and realized that I'd been listening for a while with the sound greatly deteriorated. For this reason I just do an output tube swap as one of my chores each Spring along with checking the smoke detectors and changing the oil. I also buy two sets so that I have one spare set on the shelf just in case. Never be without music!


I can't argue with that

Vladimir Lamm mandates that one tube on my amps (6N6P) be changed annually. He also told me another rule of thumb is that if the silver coating on the inside top of the tubes thins to where you can see down into the tube, this also is indication to switch tubes

Thank you for all your comments. I'll keep a keen eye on those bottles.

I find that muddiness progresses so slowly that I don't notice the first 60-70% of life is gone. I once waited until the tubes were really gone and realized that I'd been listening for a while with the sound greatly deteriorated. For this reason I just do an output tube swap as one of my chores each Spring along with checking the smoke detectors and changing the oil. I also buy two sets so that I have one spare set on the shelf just in case. Never be without music!

I'll third that motion...I have a spare 12tet on the shelf, just waiting. :) While I have a crt pj, I would imagine that the wear in output tubes is much like the ongoing degradation of bulbs in panel projectors; its funny to find the video purists that would change out a bulb after 500 or a 1000 hours, still listening to tubes that are older than their projector. Course, I imagine I'd do just the opposite - just keep moving closer and closer to an ever-dimming screen, but by golly, the sound out of my amps would be pristine. Absolutely a function of what one's priorities are.