Tube Rollings for my Tube Amp?

megasat16

I got my tube SonicFrontiers SFS-50 tube amps a few days ago. Seller packed it extremely well and it arrived safely.

Tubes came with it are EH KT88 for outputs and Sovtek 6922 for the drivers. The seller said he retubed the amp before sale.

There is a noisy EH KT88 and when the amp is powered up, I can see the bias shoot through 75mA very momentarily before it settles back at the correct bias around 50mA. This of course makes noise on the speaker for about 20-40 seconds before the tube bias settles.

The amp is otherwise very quiet after about 1 minute since turned on. There is no buzz, no transformer hum and I knew this is the cursed KT88 because I was looking at the bias meter for each tube upon powering up.

Anyway, it sounded fine after about a minute as I told and never a problem during extended listening.

But I seriously need to do some toob rollin' and gets some smokin' out of this amp.

The manual said it can use EL34 (reduced output to about 35wpc) or 6550 type tubes for output.

What are the good tubes for EL34, and KT88? I think I can use KT66, KT90 tubes in there but not too sure about KT120.

Anyone knows if the amp with KT88 tube will let you roll KT120?

What are the good ones out there? I need suggestions and all suggestions welcome!

Dawgfish

I would stick with KT88s or 6550 if your speakers are hard to drive, you like to listen at louder volumes, or you prefer more bass. The EL34s tend to have sweeter mids though. Really it would be best to try them all over time, but if you have any of the conditions listed above, go with some KT88s or 6550s. I don't know wether your amp can run the KT120s, others will have to answer that, but if they can, I would put them on your short-list. I've been running a quad for a few weeks now and I'm very impressed with them. They have great bass, wide and deep soundstage, silky highs, and mids that approach a good EL34. Their only shortcoming(to some, not me) is they don't have as much high extension as some folks prefer.

Of the KT88 types, I've had good luck with Wing Cs, Gold Lions, and Shuaguang Black Treasures. The Treasures are the best sounding, but I've had some reliability issues with them that most here haven't. I would definitely buy them from a reputable source. I thought I did, but 3 of the 6 I own have gone bad in less than 6 months. Again most here have not had the problems that I have.

I know George mentioned the Wing C KT88s sound good with the SF2, I know they sound good with my Rogue and Primaluna. The only problem with them is they are no longer made and when you find them, they typically go for $300+ a quad. I find the Gold Lions sound similar to the Wing Cs but with warmer mids and slightly less defined lows(though not bad and extension is quite good.). They are a good lower priced options.

There are two nos 6550s that I have tried, the GE and Tung Sol, and they are both excellent! They are also both costly, especially the Tung Sol. The Tung Sol (grey plate, three hole) is one of my favorite power tubes of any type. It does almost everything perfectly, if only it were not so expensive. A sleeper 6550 is the Wing C. Just make sure you get it from a good source like Upscale Audio. It's a very good sounding 6550 and they go for around $200 per quad.

There are many, many good EL34s out there. I've tried NOS Mullard XF2s, Teslas, EIs, GE 6CA7 Fat Boys, Gold Lion KT77s, and Wing Cs. I'm not going to go through each one other than say if you don't mind spending money, go with the Mullards or Teslas (fat boys are quite nice also). If you don't want to spend a lot of cash, go with the Wing Cs.

PS I know the power tubes are your main priority right now, but don't forget about the signal tubes. That will be for another day though.

heiney9

Do it right and puchase Original Tung Sol 6550's. If you're going to go new, I always like the Winged =C= from St. Petersburg NOT to be confused with Svetlana marketed tubes made by New Sensor.

Also give as much attention or more to the small driver tubes, that's where you can really customize and make an tube piece of gear shine.

Have fun............

H9

FTGV

With a custom adapter and adjustment of the B+voltage you might find these an improvement.http://www.vishay.com/docs/91210/91210.pdf
J/k Looks like Dawg has you covered,congrats and enjoy your new toy James.

megasat16

Dawgfish wrote: »

I would stick with KT88s or 6550 if your speakers are hard to drive, you like to listen at louder volumes, or you prefer more bass. The EL34s tend to have sweeter mids though. Really it would be best to try them all over time, but if you have any of the conditions listed above, go with some KT88s or 6550s. I don't know wether your amp can run the KT120s, others will have to answer that, but if they can, I would put them on your short-list. I've been running a quad for a few weeks now and I'm very impressed with them. They have great bass, wide and deep soundstage, silky highs, and mids that approach a good EL34. Their only shortcoming(to some, not me) is they don't have as much high extension as some folks prefer.

Of the KT88 types, I've had good luck with Wing Cs, Gold Lions, and Shuaguang Black Treasures. The Treasures are the best sounding, but I've had some reliability issues with them that most here haven't. I would definitely buy them from a reputable source. I thought I did, but 3 of the 6 I own have gone bad in less than 6 months. Again most here have not had the problems that I have.

I know George mentioned the Wing C KT88s sound good with the SF2, I know they sound good with my Rogue and Primaluna. The only problem with them is they are no longer made and when you find them, they typically go for $300+ a quad. I find the Gold Lions sound similar to the Wing Cs but with warmer mids and slightly less defined lows(though not bad and extension is quite good.). They are a good lower priced options.

There are two nos 6550s that I have tried, the GE and Tung Sol, and they are both excellent! They are also both costly, especially the Tung Sol. The Tung Sol (grey plate, three hole) is one of my favorite power tubes of any type. It does almost everything perfectly, if only it were not so expensive. A sleeper 6550 is the Wing C. Just make sure you get it from a good source like Upscale Audio. It's a very good sounding 6550 and they go for around $200 per quad.

There are many, many good EL34s out there. I've tried NOS Mullard XF2s, Teslas, EIs, GE 6CA7 Fat Boys, Gold Lion KT77s, and Wing Cs. I'm not going to go through each one other than say if you don't mind spending money, go with the Mullards or Teslas (fat boys are quite nice also). If you don't want to spend a lot of cash, go with the Wing Cs.

PS I know the power tubes are your main priority right now, but don't forget about the signal tubes. That will be for another day though.

Dawg,

Thanks for the great ideas! If you have only money for a set of Quad KT88 or 6550, what would you get? This tube rolling business is highly expensive for a poor SS man.

I heard a lot of good things about Treasure and C Wing but can't decide on either one yet. Upscale is near me so I can pay them a visit for my tube needs. They are a little more costly than other Internet dealers or eBay Tube Sellers though.

I have thought about the signal tubes too I will have to ask more opinions on this matter later.

heiney9 wrote: »

Do it right and puchase Original Tung Sol 6550's. If you're going to go new, I always like the Winged =C= from St. Petersburg NOT to be confused with Svetlana marketed tubes made by New Sensor.

Also give as much attention or more to the small driver tubes, that's where you can really customize and make an tube piece of gear shine.

Have fun............

H9

Brock,

I am not sure what you mean by original Tung Sol 6550. Do you mean NOS stuff that cost like $1000 for a quad?

I will look into signal tube rolling later. Thanks for the suggestion!

FTGV wrote: »

With a custom adapter and adjustment of the B+voltage you might find these an improvement.http://www.vishay.com/docs/91210/91210.pdf
J/k Looks like Dawg has you covered,congrats and enjoy your new toy James.

Fred,

Thanks for the congrats! As a primarily ss guy, I found the SF tube amp is OK. With the EH tube it came with it, I found it is lacking in a lot of low level microdynamics where most of my SS amp brings out easily but I hope to get there by toob rolling.

Those IRF are about the nicest 3 legged tubes on the side of the SS planet. After all, they are used in many of Mr. Pass Amps.

Dawgfish

megasat16 wrote: »

Dawg,

Thanks for the great ideas! If you have only money for a set of Quad KT88 or 6550, what would you get? This tube rolling business is highly expensive for a poor SS man.

I heard a lot of good things about Treasure and C Wing but can't decide on either one yet. Upscale is near me so I can pay them a visit for my tube needs. They are a little more costly than other Internet dealers or eBay Tube Sellers though.

I have thought about the signal tubes too I will have to ask more opinions on this matter later.

What's your budget? That would go a long ways towards pointing you in the right direction. If I were to just get one quad and money were not an object, I would go for the NOS Tung-Sol 6550s (the black plates are the best, but you are going to pay $$$$$ for them). People I know who have tried all of the NOS Tung-Sol variants (black plates, solid gray plate, and three-hole gray plate) tell me they are more similar in sound than they are different from each other. You can find quads of the NOS, gray plate, three-hole getter Tung Sols on the Bay for $400ish. That would be my first choice.

Honestly the Treasure KT88s sound as good to me as the NOS Tung Sols, but like I said earlier, I've had reliability issues with them that makes me a little hesitant to go back to them. Again, I seem to be in the minority on this one. When a power tube goes out on a tube amp (unless it has a protected tube grid like the PrimaLuna) it usually takes a resistor out with it and you have to take the amp to a good tech. The resistor is a fairly easy fix so if you are electronic savvy you can do it yourself, but I don't feel comfortable repairing delicate tube amps myself (learned the hard way on an Anthem Amp-1). I've had to take my Rogue to the shop twice now running the Treasure KT-88s in it.

You may pay a little more from Upscale Audio, but what you get for the extra cash is piece of mind. UA extensively tests and burns-in all of their tubes. You can have confidence that you are going to get good tubes from UA and they will stand behing their products. The extra money is worth it IMHO. Honestly if I were in your shoes, I would go by UA, pickup a quad of the WING C 6550s (get the cry treated ones if you want to splurge) and also pick up some National Japan 6DJ8 input tubes. If you really want to splurge go for the Ediswans (spectacular 6922 type). You can get the quad of Wing C 6550s and the National 6DJ8s for less than what you would pay for a quad of Wing C KT88s alone. That's what I would do and you will have sound that is light years ahead of the EH KT88/Sovtek 6DJ8s you have going on now. You can try some of the other stuff recommended above at a later point in time as funds allow.

SCompRacer

FTGV wrote: »

With a custom adapter and adjustment of the B+voltage you might find these an improvement.http://www.vishay.com/docs/91210/91210.pdf
J/k Looks like Dawg has you covered,congrats and enjoy your new toy James.

First there was the jfet, and then, the mosfet!

Life Fred said, njoy your new toy James!

george daniel

To the OP-- try to contact jerryj12--- he had a few quads of TS 6550's that tested strong and had same/close date of manufacture.

megasat16

Dawgfish wrote: »

What's your budget? That would go a long ways towards pointing you in the right direction. If I were to just get one quad and money were not an object, I would go for the NOS Tung-Sol 6550s (the black plates are the best, but you are going to pay $$$$$ for them). People I know who have tried all of the NOS Tung-Sol variants (black plates, solid gray plate, and three-hole gray plate) tell me they are more similar in sound than they are different from each other. You can find quads of the NOS, gray plate, three-hole getter Tung Sols on the Bay for $400ish. That would be my first choice.

Honestly the Treasure KT88s sound as good to me as the NOS Tung Sols, but like I said earlier, I've had reliability issues with them that makes me a little hesitant to go back to them. Again, I seem to be in the minority on this one. When a power tube goes out on a tube amp (unless it has a protected tube grid like the PrimaLuna) it usually takes a resistor out with it and you have to take the amp to a good tech. The resistor is a fairly easy fix so if you are electronic savvy you can do it yourself, but I don't feel comfortable repairing delicate tube amps myself (learned the hard way on an Anthem Amp-1). I've had to take my Rogue to the shop twice now running the Treasure KT-88s in it.

You may pay a little more from Upscale Audio, but what you get for the extra cash is piece of mind. UA extensively tests and burns-in all of their tubes. You can have confidence that you are going to get good tubes from UA and they will stand behing their products. The extra money is worth it IMHO. Honestly if I were in your shoes, I would go by UA, pickup a quad of the WING C 6550s (get the cry treated ones if you want to splurge) and also pick up some National Japan 6DJ8 input tubes. If you really want to splurge go for the Ediswans (spectacular 6922 type). You can get the quad of Wing C 6550s and the National 6DJ8s for less than what you would pay for a quad of Wing C KT88s alone. That's what I would do and you will have sound that is light years ahead of the EH KT88/Sovtek 6DJ8s you have going on now. You can try some of the other stuff recommended above at a later point in time as funds allow.

I have limited budget for this tube rolling business. I think about $400-$500 for a nice quad set of power tubes and another 4 or 5 bills for the quad set of 6922. I will not be spending 4 or 5 figures on a quad set of NOS black plate TungSol 6550. I found some old TungSol 6550s for about 400-500ish on the Bay but I am reluctant to buy from the bay. I would rather pay more and buy from upscale and be happy with it.

I have got in touch with Chris from PCX and he has been a great help. He told me I can use KT120 in the SFS-50 that it has a big enough filament transformer to cover the extra current draw. Using a pair of KT120 will probably yield about 10-15% headroom in output too. Anyway, the reason I want to try KT120 is that a lot of people testify the new KT120 is great.

But I don't need more than 10W from tube amp so I could just roll some EL34 in it. Upscale seems to have some good selection of EL34s in stock.

About the 6922, are those National are Great? How about those Amperex Gold Pins?

Honestly, I don't want to put a lot of coins in the power tube for this amp because I am looking to switch to Triode amps later on.

But most preamp or driver tube uses 6DJ8 so I am thinking to spend more on them.

But you gave me a great idea and I might just pick up a quad set of Winged C 6550s and quad set of National 6DJ8.

Argh...this tube rolling thing is too confusing for a solid state guy! lol

megasat16

SCompRacer wrote: »

First there was the jfet, and then, the mosfet!

Life Fred said, njoy your new toy James!

Thanks Rich! You remind me of Mr. Boberly when you mentioned jfet. Nicest old jfet guru who is now retired.

Tube Preamp or Boberly's all jfet preamp? It sounds the same if you don't lift the top cover up!

george daniel wrote: »

To the OP-- try to contact jerryj12--- he had a few quads of TS 6550's that tested strong and had same/close date of manufacture.

Thank you George! I will PM Jerry to see if he has a stash for sale.

Dawgfish

You can get some really nice stuff with your budget! I can personally tell you the KT120s are as good as advertised. I'm enjoying them in my Primaluna. That being the case I would take a ride over to Upscale Audio and buy a cryo'd quad of TS KT120s and a quad of Ediswan 6922s for about $500 total. The Nationals are a great tube and a bargain for the money, but the Ediswans are in a different league. The Ediswans have the mid-range of the best Amperex and Mullard 6922s with better extension at both ends. The soundstage is very wide and deep. The Amperex tubes are always a good choice in 6Dj8 types, but I find the Ediswans to be better balanced and more refined. With your budget you could buy another quad of Nationals or Amperex's to play around with and a second quad of KT120s (or the Wing C 6550s) for back-up. It's really up to you as far as what you want to spend, but you have a lot of options and they are all better than what you are running now tube wise!

megasat16

So, it is decided on a quad of KT120 cryd and a quad of Ediswans cryd for now. Thanks Dawg! You have been a great help deciding the tubes.

The lesser I spend, the better I feel about my tube amp.

SCompRacer

Dawg, bring back memories. Upscale and Ediswan 6922's, had some back in 2005. Nice tube.

I've had poor luck with cryo'd tubes, early failures. A couple pair of 5687's from ModWright, a pair of nice '50 Raytheon 5687 Kuhl-Tubes from Tube World. The second pair of Kuhl-Tubes from TW were long lasting as were the pair of '58 5AR4 Holland Black Base Kuhl-Tubes I scored on ebay cheap.

Dawgfish

^^Thats good to no about the cryo'd tubes Rich.^^ I've had good luck with my Kt120s and GL KT88s, but I have low hours on both. I'll have to keep an eye on them.

Glad I could be of help megasat16! Let us know what you think after you get the new tubes in and you've had a chance to listen for a while. Remember there will be a break-in period with new tubes, so be patient with them.

SCompRacer

I’ve bought lots of tubes and yeah, sometimes you get a dud, but I had more problems with the low amount of cryo’d tubes I purchased so I quit buying cryo’d. The failures occurred soon after install, like 25 hours or so. IIRC Dan said at the time he was going to stop offering them. Brendan at TW said things happen, and replaced them under warranty. The second pair of 5687 Kuhl Tubes lasted longer than non cryo'd tubes I had. Could have been a poor process or tube to begin with, I dunno.

megasat16

Rich,

Thanks for the info on the Cryd tubes. I thought they should offer more reliability but I understand this is in the grey area.

Not buying cryo'd tubes will save me a good amount for two sets of quads tubes too. I will talk to Upscale about them and the warranty they provide for the cryo'd tubes.

I want to stay away from the fleabay for the tubes for now. I just want a nice set of tubes because I don't hear any tubey sound from the SF.

It's probably tubes that's in there but it's more like just natural side and sounds like a good SS amp.

Is it good or bad for a tube amp? I don't know. I have heard more tubey sounding SS amps.