Tube rolling with Quicksilver Mono 60s -- from KT77 to KT88? KT 120? etc.

@oldhvymec Totally. I ran 60s RCA 6L6 black plates in my EICOs. And 5881 Tung Sol brown base. Now run the 7581A which make the amps sound like really clean and neutral 34s. QS used run the sweet 8417 until they ran out of them.

noromance4,705 posts11-28-2020 9:27amDonvito is correct. I got carried away on tubes and forgot the QSilvers. While you can generally go up from 6L6 to KT88.

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Sure would be nice if he could though, that is a good valve bottom to top.
I’ve always liked the 6L6, bottom to top in a push pull amp. Just the best for a full range valve, sure better than an EL34 or brit KT77s in the BASS region.

I’m a Mac guy, they are magic in the ol Macs MC240s, and my Cary V12r or Six Pacs. Good valve..

The Mac wont stand for a cheap valve it will sound BAD, Those Carys, blow me away, cheap valves sound VERY good in those two .. I mean REAL good..

BUT for mids.. EL34 is just the best.. They are not the best bass valve, but they are not sloppy, in the bass region just lack authority.

I like 6V6 too except they roll of a bit to quick on the top.. great late night listening valve. (Cary’s love um’)

Here is the deal on KT 90s I used them in VTL, 300 DLs, and Cary’s. They sound SS almost, to friggin clinical for me, and they hate hard domes.. Boil your ears.. powerful mids, not smooth and silky like the 77s. I think they lack DEEP bass but they have super control. The 88 is deeper more dynamic, like the 6L6, Kinda Belch it out.. (TUBES)

My oh my.. hands feel good.

Regards

Donvito is correct. I got carried away on tubes and forgot the QSilvers. While you can generally go up from 6L6 to KT88 in an amp designed for the smaller tube, you can't always go down from a big tube to a smaller tube in an amp designed to work with a bigger tube. This is because the plate voltage among other specs won't tolerate lower powered tubes. The TS 7851A maxes at 500v anode while a KT77 can stand 800v. I suspect the QS may have 600v on hand and that rules out the smaller 6L6 class tubes.

6L6 are all over the place for sale. Brand new and matched, about 115 for a matched set of 8. DON'T buy them.

IF they are Solvex, (the older solvex) it is night and day in sonics, and how long they will last, they are outstanding.

The old GE and RCA, metal cover 7581 valve.. serious valve there, super high plate voltage. REAL high, and will stand up..

The 115 sets of 8..LOL Just a bad place to even start.. :-(

WHY? Out of over 150 valves I bought in 3 lots, none of them were at 50% of the TRUE industrial 7581. Closer to 15-30% NEW.. OK, NEW..

Just under a year ago I listened to an MC240 every day for just under 3 years. I used industrial, RCA 6L6 mil/spec metal tube.. They still have 50% wear left on them.. I took the amp down for it's first EVER major service.

This is so fun, chompin' on my turkey sandwich. :-)

Regards

I see. I listed the tubes my amp can handle, that's why I'm asking. 

To adlib on the advice given,
The Person offering advice, is a very experienced owner of Tubes with access to Tubes from a Two Generation Collection.
This person has always been supportive to make Matched Tubes available for loan, and offered much valuable guidance.
The Person has been instrumental in helping others create a understanding of how Tube Rolling can influence their systems.

The advice made available to myself relating to my Monoblocks was to undertake the investigation to learn what was the best Input Valve configuration to get the best from the resident Output Valves.
This is what I did and it has proved so far to be a very economical approach, if the Pre Amp Purchase and Build is deducted from the £700

I felt more compelled to further investigate the Pre side of the System as a result of the impressive improvement to the Sound Quality being experienced 

No they are not! An equivalent tube to the 7581 is a KT66 or a 6LG type of tube!

Not in my manual. Perhaps they're equivalent?

Second new Tung Sol 7581A. They're my current tube in 2 sets of monoblocs.  I've also heard good things about new TS EL34B.

Thanks for the suggestion. It seems like you are saying to consider the preamp as an important factor. I agree. 

My experience with Tube Rolling on my Monoblocks has been carried out by adopting a advice that was offered by a very experiences Tube Roller.
It was to get the Input Valves exchanged and a Type selected that is allowing the Power Amp to deliver a level of performance that is satisfying my personal preferences.

When this was achieved, the Pre Amp in use was seeming to be the next Device in use that was needing a Investigation.
The theory being that the Input Valves may benefit further from a different Pre Amp. 
The follow up investigations with Pre Amps has also produced a Pre Amp exchange, with the result being a Slagle AVC has been removed from the role of being the Systems Pre Amp.

I have been blown away by the impression the
Nelson Pass DIY Pre Amp has made on me, the Korg B1 is a superb 
device at a very 'affordable' cost, even if a Build Service is used to produce it, as I have done.

The Mono's Output Valves have not been Rolled, and there does not feel any immediate need to undertake this investigation. 
It seems hard to consider more can be achieved to the Measures already being perceived.
I am not shut of from from the idea of Rolling Output Tubes,
but there is a level of satisfaction in place at present, that does not feel it needs to be improved upon.

'All in' I invested about £700 in Tubes and Pre Amp, off which a proportion of the outlay will be recoverable if the unselected
Matched Vintage Tubes are resold. 

What ever the Brand of Monoblocks, I can recommend my experience with Investigations undertaken of addressing the Pre Amplification Delivery to the Output Valves, as a Method to produce a overall SQ that will be seen as very beneficial.
How such a approach will then interface with any exchanges of Tubes used at the Output, is at present a unknown, in relation to my experiences.         

It also depends on the amp circuit and what input/driver tubes you use.  

Since you know KT77s now and their signature in your amps, I think it's fair consideration, the highs could be a tad more tipped up (in your amps) particularly when compared to EL34s or KT77s. Always a tradeoff. 

@glowworm -- harsh highs with GL 88? Whoa. I don't need that. Not just to play around.

@decooney
Thanks for the information. I wonder why the manual says that the KT88 can be used? BTW, I use the KT88 with my QS Silver 70 amps and Mike told me that can also use the KT 150 if I wanted to give them a try. This is from the M120 manual! Tube Complement 1 - 12AU7, 1 - 12AT7 2 - KT88 or KT150

@yogiboy
Not sure I’ve helped. Re-check with Mike for sure with your friend’s 120 amps. This is why I say to contact him, have your friend give him the serial# on the amps and ask again. I’m not sure if he tweaked the plate voltage up on mine at some point for the KT150s. Maybe your friend’s amps are okay with 88s. Yes, the "120" manual shows KT88s in two places, and I challenged him on that too. Note: check the front of the web page on the Mono 120s shows only this now "2 KT120 or KT150 outputs". KT88s are no longer listed there for Mono 120s. Manual needs updating, I don't know - better to ask mike on your buddy's version of the Mono 120s, mine are 2019 version. 

Yes, the older Silver 70, 80s, 100 amps seem to be fine to run the KT88s as I understand it, smaller transformers, likely lower plate voltage (supposedly). Same with hilde45s Mono 60s, ideal for KT88s, the sweet spot. I’d also buy a quad of KT88s right now if he’d say it’s okay for my specific mono 120 amps. I won't ask him a 4th time :)  

Watch the highs on the GL KT88s.  The bass is good, but really tiring, harsh highs.  I tried them for close to 100 hours and gave up,  IMO they were never going to change enough to be keepers. My small tubes include many of the vintage ones mentioned above, for power tubes I roll el34s, kt 77 and TS 7581a. If you’re amp can use the 7581a give them a try first. Bargain price and an excellent overall power tube. Worth a try for a minimal investment.  Great base and mid-range, with highs that are extended without the harshness of the 88. 

@decooney
Thanks for the information. I wonder why the manual says that the KT88 can be used? BTW, I use the KT88 with my QS Silver 70 amps and Mike told me that can also use the KT 150 if I wanted to give them a try. This is from the M120 manual! 
Tube Complement 1 - 12AU7, 1 - 12AT7 2 - KT88 or KT150

hilde45
No one has said a word about KT90s....

Bleh.  Stay with GL KT77s or for your upgrade, go with GL KT88s or TS KT120s instead vs. KT90 IMO.   

@yogiboy
@decooney My friend has the QS 120 amps and he has used KT88 tubes with those amps. It states this in the QS M120 manual!
Mono 120 for web (quicksilveraudio.com)

@yogiboy
IF they are the latest Mono 120s with the large transformers, have your friend call or email Mike Sanders at Quicksilver asap, and ask again, directly. Believe me, I’ve pushed it with him multiple times, fwiw. Other info...

Originally, I tried to order my Mono 120s with GL KT88s. Nope. Talked to Mike 3 separate times pushing him to share more, he keeps telling me "NO", no KT88s in my Mono 120s. I took his advice, fwiw. Says they will burn up, prematurely.

Tuning with KT150s:
And, once I got the right mid-1960s vintage dual triode Mullard "blackburn" factory 12AU7 and 12AT7 input/driver tubes, the KT150s sing now. More like a smooth KT88 sound with more depth in the sound stage and more power, dynamics.  Also tried the latest PSVANE small tubes too, a bit more midrange forward compare to the vintage Mullards.  The new Mono 120s needed a better pair of small tubes up front to precede the KT150s. Now I would not go to KT88s anyhow for the latest Mono 120s amps, even if Mike would permit it. . Once I changed coupling caps to high end Mundorf Silver-Golds, the synergy was amazing with the KT150s and Mullard small tubes up front. Super nice now.

Preamp:
They deserve a really good preamp. Now running a 6SN7 full Triode Cary SLP-98 preamp in front of the Mono 120s.  The updates to the Mono 120s and a good preamp in front of them brings them to an entirely new level. 
With the updates, I'd now put them up against the $20K KT150 Conrad Johnson monos all day long.  

The new Mono 120s have huge transformers, look for the big transformers, larger than prior version QS amps. fyi.

@tvad There's no way I'd spend more than $250 on this quad. I'd buy the re-issue not NOS.

Great advice. I'll  try really good KT88s, not sure how they'll change things but they're a basic tube and my stock JJ's are not really that good, so I'll just rotate between them and the KT77's.

No one has said a word about KT90s....

@decooney
My friend has the QS 120 amps and he has used KT88 tubes with those amps. It states this in the QS M120 manual!
Mono 120 for web (quicksilveraudio.com)

Spot on I think after clearing up some things in my head. You seem to have it well in hand.. Sometimes you,re just right.. LOL

If BASS wasn’t mentioned, I would say, stay right where you're at..
BUT YOU DID.... Bigger :-) I love EL34 valves when they're not doing bass duty, plane and simple.. I use them everyday.

30 + years I quit using valves for bass duty.. I could never get the distortion near as low as SS. 15-20% was was the best I could do.. Sounded good, BUT SS sure tightened it up.. 5 - 10% MAX.. with the right drivers.

Have fun, and good source for your valves too. That outfit actually cares and VERY knowledgeable, too. I’ve worked with them 4 or 5 times looking for some rare valves, in restorations of mine..

Regards

Thanks, Table jockey. I'll keep that in mind.

Thanks, oldhvy. I got good advice from decooney and Brent Jessee. The JJ in power position were broken in.

Yes, I did have the good signal valves in with the JJ.

And remember--I don't have JJ's in now. I have GL KT77's in powerposition.

I suppose I'm not trying to eliminate nasties as experience some other possibilities. Let's call it "Kama Sutra, tube-style."

So, perhaps a GL KT88 is a good way to play.

@hilde45, your small input/driver tubes from Brent J are fine may I suggest. I’d recommend you leave those for now and rotate the power tubes (in your specific case). The original stock KT88s were just okay, as aI recall. The KT77s you have now are giving that magical midrange and smooth highs with a little less drive on the low end. It’s a give/take situation. Really good KT88s are the safest bet in your Mono 60 amps. Upgrades to the small triode input/driver tubes is good (as already suggested, and you’ve already done that) with reputable tube provider.

And, of course, KT120 / KT150 is an option, and while the Mono 60s will accept them, may not be totally recommended in your amps. If you do go that route with 120/150s - the sound will tip away into different directions some. The KT120s are like a big KT88s, and they were a bit dry and less full sounding in my QS Mono 120s with the stock coupling caps. I jumped to the KT150s with a whole new sound top to bottom. More air on top, more bottom end punch and a yet very neutral midrange and not so forward or focused midrange like a good old EL34 has. Sound stage set back a little with KT150s in MY QS 120 amps. Reminder, the QS 120 amps were designed to run KT150s, and I cannot run KT88s, it will burn them up, not backward compatible. Yours will run them, why? TIP: I’d suggest NOT going with KT120s or KT150s in your Mono 60s, reason being is the Mono 120s were upgraded again with even larger transformers to get the most out of the higher $ KT150 tubes. 150s or the future KT170s are 15w more per tube, not ideal for your amps. Waste of $ IMO, for your amps. Can’t drive them properly.

The transformers and amp circuit itself has a lot to do with it, and each tube will sound different in different amplifiers/circuits. Yours, for KT88s.

Try not to judge how your amp sounded with the lower grade stock KT88s they came with new. There are much better KT88s out there than what you started with. Same as others, recommend you try really good KT88s. Some are having good luck with the Shuguang Black Treasure KT88s, or Gray Glass PSVANE KT88s, and of course new re-issue GL KT88s.   For reference, we removed KT150s from my friends older Jolida integrated amp (had smaller transformers, lower plate voltage.  It was not designed for KT150s. We installed a tested and well matched quad of PSVANE Gray glass KT88s with quite amazing success. Sounded like a completely different amplifier with really good KT88s. He’s had them over a year now. The did open up after 100hrs. Time will tell.  

And, if you win the lottery, try some ultra expensive EAT KT88s. Really good KT88s can make a difference too :)

WOW serious valves there. It may be GL time if those can't take the nasties out.. The JJ you have in the Powerposition were broke in?

If they were.  You had the good signal valves when you had the JJ in?

Look into that 12BH7, Even an EH, or GL swap there (that valve needs attention) might really mellow the JJs out.., But JJ is JJ (Yuk LOL)

The other "ONE", I would try is a good Tellie, NOS (you know the drill)

OK, one more thing, let the rolles settle a bit.. 20-50hours, ay.. They can be a little wonkie for a bit..

Other than that, YOUR GL choice is good, IMO

Enjoy..

"Those are honkin' tubes. Would they work in my amp? I don't know. They're not on the list the amp came with."

hilde45- They aren't available yet. My guess is if your amp is approved for KT150, they probably will be. Until they are officially released and getting the nod from the amp manufacturer of course, needs to be confirmed.

Thanks, oldhvy. Here's what I currently have (all closely matched) in addition to the outputs:

12AT7/6201 Valvo made for Amperex/Philips, gold pin selected tubes, (1962/1968)
12AX7 Amperex Holland Bugle Boy (1960/1962)
12BH7A RCA (Greyplate)

The small valves.. Roll a couple sets.. Go to someone with a good rep. for your valves IF you don’t check you own.. The guys will chime in..
I have my own gear to check valves... I’m not one to trust to many, it is always trust and VERIFY!!

12AX7
12BH7

The 12AX7 that’s your best friend. ;-)
12BH7 can add a LOT of harshness too. You have to be careful with that valve.. DON’T spend a lot of money, BUT make sure they are balanced and matched.. ASK the seller (of the valves) to help you. LOW noise, and tell them what you want and what you’ve heard... WORK with the tube seller, if he won’t help.. WRONG guy.

Small valves FIRST.. 50 - 100 for a pair. NO MORE...
Tellies, or GOOD RCAs, GE, Volvo, Mazda, Mullard, Solvex, night and day...

PSVANE, Sylvania, be careful, BRIGHT, comes to mind..

JJs nothing come to mind. C- on the ol sound scale at best.. it’s right in there with most RCAs sold as NOS, LOL rare indeed to find GOOD, stock.. you have to test EVERY one...

Have fun save your money, just a bit.. YES the GLs, though expensive are a good valve. My problem, I’ve had higher failure rates than Solvex, at 1/2 the price, and as good if not better in some ways, sonicly.. I don’t care for the 10% matching either. The solvex I use are within 5% (closer to 2% for me) GL is a good choose though. Kinda.. LOL

GE 6550s are a wonder to behold too. really one of the great tubes..of old if you can find a good old set... Push Pull units, love that valve.. Macs sure do...

When the ol hand feel good, I type away.. Friggin blabber mouth.. LOL. It's ok, I know...

Regards

@tablejockey Those are honkin' tubes. Would they work in my amp? I don't know. They're not on the list the amp came with.

Thank you, folks. And special thanks to you oldhvymec for the time you took with your post. I'm tempted to get the GL KT88s but may I ask a question? When you say "signal valve" what do you mean? I'm a bit new to this stuff. 

In my rig I have two tubes in my line stage -- are those the signal valve?

Otherwise, in my mono amps, I have (starting from the rca input plug) (a) an input and (b) a driver tube before I get to (c) two output tubes.

So which is the "signal" tube you're suggesting I play with?

Thanks again and hope your holiday was festive! 

Tighter Bass?. That’s not going to be an EL34. The KT88 is one of the best BASS valves. They are known for just that. I think the brand you were using and the signal valves, are the least expensive, and the better combos. KT88s in Solvex, GL (expensive), but JJ (yuk) in a KT88 not my first pick. That being said. The signal valves are the key to really making a KT88 sound BETTER.

I would put the JJs back in and roll the signal valves. Tellies, GOOD Black Plate RCAs, Amperex. STAY away from Sylvania, PSVANE, GEs (can be all over the map, but there are good valves)

You selected a good valve (KT77) for MidBass, great mids, and wonderful highs they just don’t do BASS duty well without some serious consideration in the speaker department.

KT90s are a consideration, again the key for me with a KT90 was the signal valve. My units that use KT90 ALL do better with GREAT signal valves. Put some so so signal valve in front of them, they sound harsh, sharp, bloated mids, boiling highs. The right signal, valves.. Night and day.. BUT I still think a good KT88 for the money. You can’t beat it.

120, 150s. Never used the valves, of the two the 150 is getting the better reviews, would I try them, yes.. Would I pay for them NO...

I’ve used 450, 750, and 1200 watt valve amps..ALL KT88/90 base.
FOR the $$$$$ you can’t beat them..

 AND a Happy Turkey Day to you and yours. Now turkey sandwich day for me.. My favorite!

Regards

Wait until these are released
https://primalunablog.com/2020/10/30/tung-sol-kt170/

You can be one of  the first to report on sonics. Should be a turbo charged KT150.
The KT150's get positive reviews. Just not much info on them yet.

I suspect you're in the sweet spot now.