Solid State Confessions

mep

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Last weekend during the evening I had just turned my stereo on in order to let everything warm up before my listening session. All of a sudden, a big electrical storm hit. Before I could run downstairs to power down my gear, a big bolt of lightning lit up the sky and we lost power for a couple of seconds. I knew that meant that all of my gear had powered down and was now powering up. I ran downstairs and shut everything down. After the storm had passed through, I powered everything back up again. When I did, I noticed that my amp was making some popping noises through my right channel speaker.

The next day I flipped my Jadis on its side and removed the bottom cover in order to check the bias and health of my output tubes. When I was checking the bias, I found I had one dead output tube in the right channel. Bummer. I had just replaced all of the output tubes last June, and when you are buying 12 KT-88 tubes at once, that’s almost $800. Because of the wacky bias scheme that Jadis uses on the Defy 7 MKII, you only have one bias pot for each bank of 3 tubes. That means the tubes have to really be matched carefully. There are only two sources I really trust to match output tubes, and that is Upscale Audio and RAM Labs. Because of the bias scheme and the fact that the tubes had been in there since last June, I went ahead and bought 3 matched tubes from Upscale Audio so I would know they were all matched.

Not to get sidetracked here, but for anyone who owns or is contemplating owning a Defy 7, I will give you a little advice. When you are setting the bias, do not unplug your interconnects from your amp and leave the Jadis inputs un-terminated. I learned this lesson the hard way. I could not get the bias to adjust higher than 3.1v DC on any bank of tubes. When I turned the bias pot up to increase the voltage, my Fluke 77 meter would read “OL” which of course stands for overload and would normally mean you have your meter on the wrong range (set too low) or you have a short. I shot Tomex a PM to ask him what he thought was going on and he was as bum-fazzled as I was. Tom also commented on the wacky bias scheme that Jadis uses and I’m in total agreement. I like to see a bias pot for each output tube, and it should be easily accessed from the outside of the amp with test points that are also accessed from outside of the amp. I really don’t enjoy having to flip a 100lb amp on its side, remove the bottom cover, and then have to measure voltage from one side of a fuse on each output tube to ground and sticking a screwdriver into each of the bias pots while being careful not to come into contact with any high voltage. It’s not a job for the timid or weak. Anyway, the cause of my bias issue was I had unplugged the interconnects from the amp before I flipped it onto its side and left the inputs un-terminated and that was causing some instability in the amp. As soon as I plugged the interconnects back in and powered it back up, I was able to set the bias just fine.

Which now leads me to the next part of the story. While I was waiting for the tubes to show up, I got out my old trusty Phase Linear 400 Series II amp and hooked it up so I would have some music to listen to. I bought the Phase Linear from a local repair shop in Bloomington. It’s run by an older Greek gentleman who is really good at fixing any audio gear. I was in his shop to have my Teac 4 track worked on and I spotted the Phase Linear out of the corner of my eye. Thinking this could possibly make a nice back-up amp for emergency use, I bought it. He had just gone through it and replaced the main power supply filter caps with larger value caps which he assured me gave it better bass punch. I was just glad to know it had new filter caps because they are time bombs after 20 years.

So I hooked up the Phase Linear and powered on the system. I went ahead and fired up the digital music server/computer to let everything cook. Ever since I downloaded Foobar a couple of weeks ago, my digital has never sounded better as I commented on in another thread. Well, now it even sounded better still. The bottom end is much better which shouldn’t come as a surprise, but I wasn’t prepared for how good it sounded from top to bottom, and this was on digital no less. I just kept shaking my head and thinking there is no way an old SS amp should sound this good. Clean, quick, transparent, and with an overall purity I just didn’t think was possible from SS. This little amp is rated at a little over 200 watts at 8 ohms and it sounds like it has a 1000 watts. I previously owned a Pass Labs X-250 which is an impressive looking beast if you like audiophile approved thick face plates that are layered and have the Cyclops meter eyeball underneath all the layers. I hated that amp. Myles described it best in two words, “thin and wimpy.” The Pass Labs is a huge amp that weighs at least twice what the Phase Linear weighs and of course is a much newer design. If I didn’t know better, I would have sworn the Pass Labs had 25 watts per channel, not 250. I sold the Pass Labs amp because I thought it was a cruel joke and it made me think SS sounded worse than I had remembered.

So, even though I had my Jadis fixed and the bias set correctly, I didn’t bother to put it back into my system for last night’s listening session. That would normally never happen. I wanted to listen another night to the Phase Linear to see if I was dreaming about how good I thought the system sounded with the Phase Linear in it or did it really sound that good. The answer is, it really sounds that good and that is messing with my core belief system. With the addition of Foobar and the Phase Linear, my digital music sounds really good for the first time. I can accept it and appreciate it. Of course I still love my tapes and LPs.

The bottom line is that I’m feeling a little conflicted here at the moment. I need to put the Jadis back into the system, but it won’t be tonight. I still have more conclusions that need to be drawn.
 

microstrip

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I have no experience with the Phase Linear, but I have owned the Defy Da7 - to be precise twice. Once with Sonus Faber Amators and the other occasion with ESL63. Both times I got them used.

First thing I would ask is what is your preamplifier?

Now for the solid state. Although I have large tube power amplifiers ( the old VTL MB750s)
from time to time (usually at hot days) I listen to solid state amplifiers for short periods. Usually for the first days I enjoy having a different type of sound, more dramatic and with better control, but as soon as I start listening to recordings I know pretty well or for longer times I start noticing that I am missing some part of the recording, and music seems less enjoyable. (I have to say that the solid state amplifiers I use are not equivalent in price to the VTLs - the Classes M600 are just a dream).

Every time a tube blows any tube man feels his convictions shaken. Mean time between failures of solid state equipment look so promising compared to the thousands of hours between re-tubing. But think that usually after a storm a solid state amplifier will leave you with an enormous bill ...
 

Ron Party

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I wonder if there is a convenient way you could have the best of both worlds, i.e., have both amps connected with some sort of switch where you simply could choose which amp you wanted to use without any degradation in SQ. More knowledgeable folks than me (hint, hint: Gary, are you listening?) might be able to answer this one.
 

mep

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Apr 20, 2010
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microstrip-My preamp is the Counterpoint SA-5.1 which just came back from its maker with some new upgrades. I previously have had the line and phono stages rebuilt and all the RCA jacks replaced. This time I had the power supply upgraded. The power transformer was replaced with the Plitron, all of the power supply caps were replaced and some other passive parts. The umbilical cord from the outboard power supply to the preamp was replaced with Cardas wire. The volume pot was replaced with a DACT pot. The SA-5.1 is one of the few tube preamps on the market that has a pure tube power supply that includes not only the rectifier, but also the voltage regulation.

I get what you are saying about enjoying a new type of sound and then realizing you are missing something. I have felt that way in the past. I may feel that way again real soon. It usually only takes me a couple of hours to want to remove anything SS from my system which is why I feel surprised right now. After my problems I had with keeping my beloved Quicksilver MS-190 amps operating, I swore off tube amps for a short time and that is why I bought the Pass Labs X-250. That quickly soured me on SS and I bought the Defy 7 MKII and never looked back. And yeah, tube breakdowns can make you question your sanity with regards to loving tube amps.
 

fas42

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Mark, from me the simple answer would be that through a series of intentional and accidental steps you have minimised key problems in your system to a point where the underlying quality of your digital recordings is being allowed to shine through, without struggling to do so. From the sound of it, your previous digital setup was generating sufficient problems, in of itself, and in turn interfering with the functioning of SS amp to cause plenty of dissatisfaction; hence the need for tube gear to tame the sound.

Those Pass are classic AB style amps, meaning they are particularly susceptible to power supply quality issues, which in turn are sensitive to ugliness on the mains power coming in. Everything in the system can have an effect on everything else, nothing can be considered in isolation; a holistic approach to improving the system I have found to be the most effective way of moving forward ...

Frank
 

tony ky ma

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Aug 21, 2010
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Mark- Why don't you to make a pair of RCA shorting plug which is very easy to do instead of keep the interconnect on, that is more easy way in service amp, short the in put and load the out put with dimmy resistor is the safe way for tube amp in service, IMO multi power tubes for more power cann't be as good as just a singal tube because they won't be 100% match, so far you have not tried any direct heating real triod in singal end singal tube amp yet ? what is the min power needs for your speaker ? I am quite sure that you will like it to work with your all tubes pre amp
cheers
tony ma
 

mep

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Mark, from me the simple answer would be that through a series of intentional and accidental steps you have minimised key problems in your system to a point where the underlying quality of your digital recordings is being allowed to shine through, without struggling to do so. From the sound of it, your previous digital setup was generating sufficient problems, in of itself, and in turn interfering with the functioning of SS amp to cause plenty of dissatisfaction; hence the need for tube gear to tame the sound.

Actually, you kind of have that backwards. I didn’t like the sound of my digital files when I was listening to them via Media Monkey and my Jadis. I never needed tubes to tame the sound. I did need to stop Media Monkey from monkeying around with my digital files though. All the time when I was displeased with my digital music, the Phase Linear was stored in my workshop room waiting for my Jadis to break.

Those Pass are classic AB style amps, meaning they are particularly susceptible to power supply quality issues, which in turn are sensitive to ugliness on the mains power coming in. Everything in the system can have an effect on everything else, nothing can be considered in isolation; a holistic approach to improving the system I have found to be the most effective way of moving forward ...Frank

Frank-you do understand the vast majority of amplifiers used for audio are Class A/B amps don’t you? And all amplifiers regardless of class of operation are susceptible to power supply quality issues. The power supply is the heart and soul of any component. They need to be well designed for the job they are going to do and well built.
 

mep

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Tony-I actually have shorting plugs laying around. Normally I just leave the interconnects plugged in. Why I pulled them out the other day I have no idea. I guess I thought it would be a good idea to remove them before I flipped the amp on its side. And when I bias the amps, I do use 100 watt dummy load resistors. And you are right about the no 100% match. That is a fact. And there is no guarantee that as the tubes age, they are going to age in the same manner. If all my tubes were perfectly matched, each tube would measure exactly 4v DC in my amp and of course they don't.

I could probaby get by with your 50 watt design. How much are the power and output transformers?
 

garylkoh

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I wonder if there is a convenient way you could have the best of both worlds, i.e., have both amps connected with some sort of switch where you simply could choose which amp you wanted to use without any degradation in SQ. More knowledgeable folks than me (hint, hint: Gary, are you listening?) might be able to answer this one.

Anytime you add a switch and a piece of wire, you lose SQ.

The best of both worlds would be an amplifier that has the soul of the Defy7MkII and the bottom end and clarity of the Phase Linear. One solution will be for Mark to buy another Defy7MkII and run them as strapped parallel monoblocks. He won't get 4 times the power like a bridged SS amp, but he will have half the output impedance, double the iron in output transformers, and may give him the best of both worlds.
 

garylkoh

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IMO multi power tubes for more power cann't be as good as just a singal tube because they won't be 100% match

+1

I would add transistors to this statement too. Multi-transistor high-power SS amps exhibit the same problems. I think that's why the FM Acoustic amps sound so good (to my ears anyway). They are obsessive about matching components - including the output transformers.
 

mep

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Gary-you mentioned this to me before and the idea sounds very good. What doesn't sound good is trying to keep two Defy 7 amps running and in tubes. Now we would be talking about $1,600 to retube the amps and that cost will never go away and willl probably go up. I do think the secret to the Jadis amps is their output transformers. They are works of art and they are massive. The output transformers on the Defy 7 look like they belong on a 300 watt amp. I assume the Defy 7 is mainly Class A because of having 6 KT-88 tubes per channel and only claiming to have 100 watts of output power. Most tube amps that had 6 KT-88s per channel would be rated for at least 200 watts per channel.
 

tony ky ma

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Aug 21, 2010
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I could probaby get by with your 50 watt design. How much are the power and output transformers?[/QUOTE]
Mark
All my transformers are made by Electric Print Audio, 50 watt in copper less than $500 but in silver will be more than $4000. you can email to Jack and ask for the price and say friend of me, to see if he can give you a good price, power trnasformer, I just use the hammond product not too expandsive around $100 and something,
regard
tony ma
 

garylkoh

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Gary-you mentioned this to me before and the idea sounds very good. What doesn't sound good is trying to keep two Defy 7 amps running and in tubes. Now we would be talking about $1,600 to retube the amps and that cost will never go away and willl probably go up. I do think the secret to the Jadis amps is their output transformers. They are works of art and they are massive. The output transformers on the Defy 7 look like they belong on a 300 watt amp. I assume the Defy 7 is mainly Class A because of having 6 KT-88 tubes per channel and only claiming to have 100 watts of output power. Most tube amps that had 6 KT-88s per channel would be rated for at least 200 watts per channel.

Sorry, I'm repeating myself. The Defy 7 is probably the best tube amplifier I've had long-term experience with. If you can find them, my Genesis M60 monoblocks strapped together in mono sounds almost as good. Unfortunately, I don't even have 2 pair anymore. On the 'gon a pair might cost as much as re-tube cost on the Defy7's and you don't need matched tubes. Each tube has an externally accessible bias pot.

The secret definitely is in the output transformer.
 

fas42

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Actually, you kind of have that backwards. I didn’t like the sound of my digital files when I was listening to them via Media Monkey and my Jadis.
So the problems were more subtle than I realised. There was an interesting article by Stan Curtis in HiFiCritic, repeating what I believe others have said, that it can be extremely difficult to get a bit-perfect, or correct, version of a digital file to be fed to the DAC on a Windows system -- every layer of the software may attempt to fiddle with or filter the information, which is exactly what you don't want ...

you do understand the vast majority of amplifiers used for audio are Class A/B amps don’t you? And all amplifiers regardless of class of operation are susceptible to power supply quality issues.
Yes, but AB more so than A or D. This is a simple fact of life because of the nature of the current delivery to the output stage when pushed into the class B region, which then looks like a rectified sine wave.You have lots of very high frequency harmonics in the mix, which the more sensitive areas of the amp have to be able to ignore.

Frank
 

Phelonious Ponk

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Don't underestimate the power of the dark side, Mark.

Tim
 

mep

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I changed my mind. I decided to put the Jadis back into the system for tonight's listening session. I just played Lyle Lovett's song North Dakota before I switched out the amps. I will have to do this again, but at the very beginning of the song, the drummer is very softly tapping on a cymbal. As the song goes on, he starts striking the cymbal harder which makes it easier to hear. Unless I'm confusing the beginning with the middle of the song, I swear that you can hear the drummer softly hitting the cymbal easier and more clearer with the Phase Linear at the beginning of the song than the Jadis. Frantz, since you are the one that told me to get this album, what do you hear at the beginning of the song? Can you hear the drummer softly hitting the cymbal?
 

fas42

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Can you hear the drummer softly hitting the cymbal?
Digital either works correctly in a system or it doesn't, in terms of sounds being reproduced correctly. This type of musical event can be made a mess of, or be totally convincing, almost without limit. If working correctly, the higher the resolution of the rest of the system the more finer and finer detail will be reproduced cleanly, so I would not be not surprised if the tweaked Phase Linear did a better job than the Jadis in this sense ...

Frank
 

Phelonious Ponk

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Lower noise floor = less masking, better resolution of the subtlest details at lower volume. It's no surprise that the Phase Linear does this well. I wouldn't be surprised if that cymbal was clearer as the volume comes up, too. Clipping and metal tweeters make harsh bedfellows. What you're hearing is headroom. An amp that can drive your speakers hard without even getting up out of its chair. In my view, there can't be too much headroom, and there really is no substitute for it. The only question in my mind is what was wrong with the Pass Labs?

Welcome to the dark side. Next up? Active. Bwahahahahaha!!!!!!!!!!!!!!!!!!!! ;)

Tim
 

microstrip

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(...) IMO multi power tubes for more power cann't be as good as just a singal tube because they won't be 100% match, so far you have not tried any direct heating real triod in singal end singal tube amp yet ?

Although it is not clear for me if your are addressing pushpull amplifiers or paralleling several tubes to get a composite tube with lower plate resistance and higher current capability, I should refer that paralleling tubes per si is not a bad thing. We have two important parameters in power tubes - plate current versus bias voltage and transconductance. If you select and match the tubes you can get a composite tube with very good characteristics. Each of my VTLs have 12 6550C tubes - I select them in a way that the sum of the tranconductances of the push side equals the one of the pull side.
 

mep

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microstrip-I don't think it matters with regards to push-pull or parallel single-ended. The point holds true for either type of amp. You are never going to get two output tubes to match perfectly, let alone 12. I am dealling with 6 per channel. I buy the best tubes I can and as matched as they can be. They are not perfectly matched. They are just *close.*
 

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