[fkclo]

Hi Phil,

Thanks for your account of your interesting journey into tube amp design and your detailed explanation of the questions raised. The brochure is really nice and I am amazed to see the boutique parts being used as "standard" in the Valvecode.

How sensitive is the rectifier tube on the sound ? I noted the ValveCode uses 5U4GB but wonder if it can also take a 274B, GZ33, and 5U4G ?

On the casing, have you thought of having the ValveCode in hardwood trim to give it a full retro look ?

Best regards,
F. Lo

 

[Skylab]

Input tube options include 6SN7, 6SL7, 6BL7

Output tube options include 6SN7, 6BL7, and 6BX7

Rectifier tube options include 5U4 (G/GB) 5AR4A, GZ34

 

[ppl]

Francis are you referring to the Sophia Electric > 274B/274A< Rigid & Mesh Plate Tubes? Yes Sir they do look like some mighty fine bottles. I believe they would work in the Valvecode based upon the data on their site, however they caution about having a lot of capacitance after the rectifier tube, with 10 uf the largest value useable. The Valvecode meets this aspect of the tube requirements as there is only a 1.0uF film capacitor directly attached to the tube and that value is within the tubes ratings. However, the Valvecode has a massive amount of capacitance after going through two separate 1k resistors (One for each channel) there is about 500uF. Since those two branches go separately to the Right and Left channel the tube effectively sees 500 ohms and 1,000uf of capacitance. In addition to another series resistor mega cap affair on each channel powering the input stage.

I sure would like this tube to work since the night view would be gorgeous with the GLOW. I will contact Sophia and inquire what changes if any would be required to use that tube. As far as the rectifier tube making a difference in the sound… I tried the 5U4GB 5U4G 5Y3GT GZ34 and 5AR4A. All sounded noticeably different yet all worked fine except the 5Y3GT gave about 50 less volts of high voltage than the others. The Valvecode is sensitive to everything except it apparently don’t care what is connected to it’s output. The Valvecode handles most dynamic headphones quite well including K-1000, however the source, cables, power cords and most definitely tubes. The guys at the Seattle meet used one of them power conditioners to get rid of the Hum and noted several different power cords made quite a difference sonically.
Yes Francis this Amplifier has Brads Accountants screaming………

 

[erikzen]

Quote:

Originally Posted by ppl /img/forum/go_quote.gif Thank you Eric for your thoughtfully honest review of my latest Design. I can completely relate to your fear of Tubes. I like yourself come from a Solid state background and also was completely put-off by high voltages and the horror stories I hear often about this or that Tube Amp blowing up for no apparent reason. I even have to witness such an event live and in person at one of the few meets I attended. This incident also involved electrostatic headphones. This totally convinced me I wanted nothing to do with tubes or high voltage, even thought the mega detail of electrostatic cans can be captivating! one must ask themselves is this really worth your life???

Phil, it's my pleasure to have the opportunity to comment on one of your designs. After having spent some time corresponding with you, I know that you are a very dedicated and passionate music lover and audio designer, the former being the operative word. I know that when you design an amp you have yourself in mind first and not the bottom line or some new audio trend. It's been a pleasure to be able to share some of your passion for music.

Fortunately, or unfortunately as the case may be, having the Valvecode in my house for a month has removed a lot of my fear of the unknown with tubes. I say unfortunately because having to send the Valvecode on to Skylab left an empty feeling in my heart and an empty spot in my system. I couldn't resist and ordered one of those Chinese tube amps. I know they are toys compared to the Valvecode but I want to continue increasing the knowledge quotient. But after reading all of the precautions you took to make sure the Valvecode is safe, I'm worried that other manufacturers will not be as fastidious as you. I'll have to keep an eye out for arching tubes, glowing plates and exploding headphones.

As far as what that additional space should be used for, I'm probably the least qualified to comment on electronic circuit design but a pre-amp out sounds like a logical choice.

What about some kind of tone control like you've had on previous solid state amps, such as your now famous bass boost control? Could you have good old fashioned bass and treble controls?

I have no idea what's involved with creating a balanced input, but it seems that many people who are into high end headphones consider balanced the way to go. Does that even make sense with this amp? I like fkclo's idea of having some wood trim on the casing or how about a wooden knob for the attenuator?

I was wondering also if you could answer directly a couple of questions in this thread that others have asked.

Quote:

Originally Posted by Rob N 6EM7 still has dissimilar sections,one high mu one low mu.How does it work in this amp?

Is this tube a dissimilar triode as Rob N says? If so, what is the disadvantage, if any of using it in the amp? I used it with good results but how does it sound to your ears?

Quote:

Originally Posted by jpelg Perhaps that's why we didn't hear significant changes when we played with that switch at the meet? Can you elaborate how this is implemented in the circuit & should be used by the listener?

I wasn't 100% sure how to best utilize the impedance switch. I think that the right hand headphone jack bypassed the switch. Can you confirm that?

 

[erikzen]

Quote:

Originally Posted by Skylab /img/forum/go_quote.gif Rectifier tube options include 5U4 (G/GB) 5AR4A, GZ34

According to some additional documentation Phil gave me the 5AR4 may result in excessive high voltage and is not recommended. The 5Y3GB will also function but excessively low voltage could result.

 

[Skylab]

That is good to know! I have a bunch of 5U4G's, so I am set on that for the review.

 

[fkclo]

Quote:

Originally Posted by ppl /img/forum/go_quote.gif Francis are you referring to the Sophia Electric > 274B/274A< Rigid & Mesh Plate Tubes? Yes Sir they do look like some mighty fine bottles. I believe they would work in the Valvecode based upon the data on their site, however they caution about having a lot of capacitance after the rectifier tube, with 10 uf the largest value useable. The Valvecode meets this aspect of the tube requirements as there is only a 1.0uF film capacitor directly attached to the tube and that value is within the tubes ratings. However, the Valvecode has a massive amount of capacitance after going through two separate 1k resistors (One for each channel) there is about 500uF. Since those two branches go separately to the Right and Left channel the tube effectively sees 500 ohms and 1,000uf of capacitance. In addition to another series resistor mega cap affair on each channel powering the input stage. I sure would like this tube to work since the night view would be gorgeous with the GLOW. I will contact Sophia and inquire what changes if any would be required to use that tube. As far as the rectifier tube making a difference in the sound… I tried the 5U4GB 5U4G 5Y3GT GZ34 and 5AR4A. All sounded noticeably different yet all worked fine except the 5Y3GT gave about 50 less volts of high voltage than the others. The Valvecode is sensitive to everything except it apparently don’t care what is connected to it’s output. The Valvecode handles most dynamic headphones quite well including K-1000, however the source, cables, power cords and most definitely tubes. The guys at the Seattle meet used one of them power conditioners to get rid of the Hum and noted several different power cords made quite a difference sonically. Yes Francis this Amplifier has Brads Accountants screaming………

Hi Phil,

Yes, indeed I am talking about the Sophia Princess 274B. I am using a pair on the WA5 and also works with a pair of 6SN7 as driver. For most of the music these 274B suits me better than my beloved metal based GZ34. So, if the ValveCode can use the 274B this will be good news. Yes, the tube glow is very nice and the bottle actually looks better than most 5U4G I have used.

From what you say, I can tell the ValveCode can be a lot of fun, given its sensitivity and responsiveness to what is connected to it - power, interconnect, tubes, headphones and sources. Really looking forward to hearing one.

If I have a choice, I would like to get a ValveCode maxxed out upfront instead of shipping the unit back and forth for 3rd party upgrades. Not only will be character of better parts are fully leveraged in the design, but it also avoid the whole spectrum of risks that associated with after-market or DIY upgrades, as I am no DIYer so your approach is exactly what I prefer. I am especially glad to learn that the ValveCode can handle the K1000 well - this is always on my wish list for ValveCode but am too afraid to ask.

Just curious - have you ever consider using silver output transformer for a cost no object version of ValveCode ? I asked, but know very well this will be beyond what my wallet can provide.

F. Lo

 

[Skylab]

With Erik's blessing, I will make a few comments in this thread about the Valvecode.

Unfortunately, the Valvecode prototype, which was hand built by Phil, was pretty beat up when I received it. Some bolts were loose and stripped, and one of the tube sockets had problems. Also, As Erik experienced, there was a pretty loud hum in the left channel. It was less noticeable with my 600 ohm headphones than my 80 ohm ones (regardless of the position of the impedance switch), but it was audible enough that it was intrusive on the music in most cases. As such, I told Phil I could not do a full review, and he agreed. Depending on how things shake out, I may get a chance to review a production unit, and if so, I will do a full, separate review then.

Aside from these issues, and using Tung-Sol 6SN7's as the driver tubes, the amp sounded very good, although a little on the light side. I tried several different 6SN7's as the input tubes, and in every case the overall sonic signature was very clean and revealing, but lighter and leaner than it should be, and more so than I think anyone would want from a tube amp.

Phil suggested I try the 6BL7 as the input tube. This meant I was using 6BL7's as both input and power tubes. And with the 6BL7, the Valvecode sounded terrific (aside from the annoying hum). It was really excellent in this configuration - lush and transparent at the same time, and well balanced. I could tell there was a great amp in there waiting for me to hear it if only the prototype weren't on it's last legs.

But I do think Phil needs to figure out why the Valvecode sounds so good with the 6BL7 and sounds thin with the 6SN7. I used Tung-sol 6SN7GT's from the late 40's that never sound thin. I'm worried that the Valvecode is voiced on the lean side, since the 6BL7 is known as a lush, fat, warm sounding tube. So if the Valvecode sounds "right" with the 6BL7, this means it will only sound that way with that particular tube.

The issue with that is that the 6SN7 is the much more common, popular tube. Sure, the 6BL7 is cheap, but there are hoards of audiophiles with piles of 6SN7's they would like to be able to use. I personally think it will be a problem if the Valvecode sounds thin with the 6SN7.

But again, this is just a very early observation on a prototype that was clearly having some problems. I have relayed all this to Phil. If he and Brad from Triad elect to make this amp a 6BL7 based amp, I am confident that it will be truly excellent sounding. It may be also be possible for Phil to tweak it so that it sounds good with the 6SN7 as well, and in this case, I think it will have broader appeal.

 

[xtreme4099]

Sounds like somethings broke .. the 6sn7gt that came with it was lush and romantic sounding with a thicker sound than the 6bl7s... well anyways thats too bad sky, phil's gotten his boards in so im sure you probably be getting one of those to listen to sometime.

 

[erikzen]

I was very disappointed to hear that the amp arrived at Skylab's in such poor condition. I can't help but take some responsibility for that. I did try to pack the amp securly but there must have been an issue with it prior to shipping it out, and the trip from New York to Chicago only made it worse.

When I first received the amp, I really didn't notice any hum. I tried a variety of the tubes that were included and can't really say I would have characterized any of them as thin or light. As I wrote, this was the first amp I heard the SA5000 with, that made them sound full, rather than just analytic. I stand by my original impressions of the amp and think it truly is a great piece of work.

It was after the meet that I started to notice a bit of hum but wasn't sure if it was a new development or if I hadn't paid any attention to it previously. I don't remember anyone at the meet commenting on hum so maybe something happened to the amp at the meet or when I was trasnporting it back home.

It also seems like that whatever was wrong with the amp before I sent it to Chicago only got worse because although the hum was audible, it was very low and did not seem to be coming from only one channel.

I have already apologized to Phil and Brad for this. Phil, always a gentleman, just said "sh!+ happens". I want to reiterate though that I am more than willing to take responsibility for this and whatever I can do to make up for this, just let me know.

 

[ppl]

It is somewhat disappointing to have ones equipment Malfunction just when you least likely to want a breakdown. About 60 Years ago Mr. Murphy Assured humanity that what can go wrong will go wrong. If it were not enough to have Murphy to worry about we have the all looming never predictable Force Majeure. Well like it or not, stuff happens that is beyond anyone’s control so we simply move on to the future. I want to personally thank all the people that helped get the Valvecode out into the world to be experienced. A lot of good came out of this like folks discovering there true path to Audio nirvana, and Fear of the unknown can at times cloud ones vision so they lose track of adjoining paths that might be worth exploring. Additionally in spite of the technical issues a lot of people got to hear the potential of this Wonderful Amplifier

Speaking of the future Brad is having the limited 1st production run of valvecodes made at this moment. I believe that one will be available to send back to skylab in about 30-45 days. We also decided that since this is an expensive Amplifier and already contains some boutique parts, that OPTIONS would be available. The output transformers could be upgraded at the customer’s request. At this time if someone wants a Valvecode with something different the standard Hammond Iron TRIAD Audio supplies with the Valvecode they could make arrangements to have there transformers of choice installed as long as they meet the electrical specifications of the Hammond standard iron. Another option is alternate voicing. Based upon skylabs suggestions we are going to offer two voicing options one is my preferred sound (Prototype Voiced using 6BL7) using the 6BL7’s driving the 6BX7’s, or what Skylab suggested of providing optimum voicing with the 6SN7 tubes since this is what most people will use. Well now you can specify which you prefer at the time of ordering (We just need separate names for these options) Oh and we could also install AKG K-1000 jacks since the Valvecode has plenty of output for these can’s. Another option is balanced inputs via Input transformers. As you may already be able to tell TRIAD Audio intends to make the Valvecode one serious entry in the top tier vacuum tube Head Amp Arena.

 

[Skylab]

Erikzen - the amp was very well packaged when you sent it to me. I don't think this was your fault in any way. In fact, it's nobody's "fault" - it's just the issue of a prototype which got a healthy workout and got tired

So no worries!

Regarding the tubes that were included to use with the prototype - the 6SN7's that were in there were labeled "Russia 6SN7GT". As such, I did not try them - I have no enthusiasm at all for Russian 6SN7's, having found them generally not to sound very good. I did not even look in the boxes, but I assume that is what was actually in there. So I cannot comment on how the Valvecode sounded with those. I used some of my own 6SN7's, of which I have a healthy number of excellent sounding varieties. But Phil did agree that the Valvecode prototype was voiced with 6BL7's, and as such would sound thin with 6SN7's. He has outlined that he has come up with a solution for this - which sounds like the perfect solution!

Phil - that is all great news. I have no doubt that the ValveCode will be a terrific amp. Based on what I was able hear, I am sure that the ValveCode is, in it's final production, going to be a tremendously good amp.

Exciting stuff!

 

[erikzen]

Quote:

Originally Posted by Skylab /img/forum/go_quote.gif Erikzen - the amp was very well packaged when you sent it to me. I don't think this was your fault in any way. In fact, it's nobody's "fault" - it's just the issue of a prototype which got a healthy workout and got tired So no worries!

I appreciate everyone's support in this matter and feel privileged to have been able to get in on the "ground floor" with this amp.

Quote:

Phil - that is all great news. I have no doubt that the ValveCode will be a terrific amp. Based on what I was able hear, I am sure that the ValveCode is, in it's final production, going to be a tremendously good amp. Exciting stuff!

No doubt! Now I just need to start saving my sheckles so I can buy one of these. Perhaps my kids don't really need to go to college after all.

 

[fkclo]

Quote:

Originally Posted by ppl /img/forum/go_quote.gif We also decided that since this is an expensive Amplifier and already contains some boutique parts, that OPTIONS would be available. The output transformers could be upgraded at the customer’s request. At this time if someone wants a Valvecode with something different the standard Hammond Iron TRIAD Audio supplies with the Valvecode they could make arrangements to have there transformers of choice installed as long as they meet the electrical specifications of the Hammond standard iron. Another option is alternate voicing. Based upon skylabs suggestions we are going to offer two voicing options one is my preferred sound (Prototype Voiced using 6BL7) using the 6BL7’s driving the 6BX7’s, or what Skylab suggested of providing optimum voicing with the 6SN7 tubes since this is what most people will use. Well now you can specify which you prefer at the time of ordering (We just need separate names for these options) Oh and we could also install AKG K-1000 jacks since the Valvecode has plenty of output for these can’s. Another option is balanced inputs via Input transformers. As you may already be able to tell TRIAD Audio intends to make the Valvecode one serious entry in the top tier vacuum tube Head Amp Arena.

Thanks for the great news, Phil. I do appreciate if you can "warn" us of the ballpark so that we all start doing two jobs day and night to save up for it

F. Lo

 

[Frihed89]

My question is for the designer. If any one knows him, and you think it relevant, can you pass my question at the bottom along? I read all the URLs and this amp sounds very promising to me.

The 6SN7GT was designed to run at 300 VDC plate. The 6BX7GT and 6BL7GT were designed for 500 VDC.

I can run them at either voltage in my MPX3 SE Slam as output tubes (and have a Supra power supply to deal with this) and let me tell you they both sound a lot better at 500VDC than 300VDC.

Now, I see they are slated for all of the slots in the cascade circuitry, as are the 6SN7GTs, so I concluded the plate voltage must be around 300VDC on all these tubes?

Mikhail is using a cathode follower as I recall and this is a cascade, which I know little about, so my "untuttored" comment is: Is my comment about the different voltages a potential issue?