[ebag4]

Hi guys.  I have it on what I believe to be good authority that the 10Y tube is all that when it comes to audio amps, "blows away 45s, 300Bs, and 2a3s" is what I was told.  I have decided that I want to build the amp (I am also considering having it built) but I wanted to bounce a couple of things off you that may have heard/built these amps. 

I only found one complete schematic on line and I wanted to hear from those of you in the know what you think of this design, so please comment to your hearts content:




I would also like to hear from those who have heard this amp, what did you think of the sound? 

This amp will be fed by a Dodd Buffer, it will be hi-passed at about 140Hz, it will pwer the coaxials of the GR Research V1.

Thanks for reading!

Ed

[Indiansprings]

What are the specs on that?

[srb]

Okay, I haven't heard an amp that uses a 10Y tube.  But even so, right off the bat I would consider anyone who says that a particular tube type or amplifier topology "blows away" another to be of dubious authority.
 
Steve

[ebag4]

What are the specs on that?

10 / VT-25 Hytron
(Vplate=220V, Vgrid=-7V, Iplate=25ma, Mu=6, Rp=6Kohms)
(10=VT25 with thoriated tungsten filament: Ef=7.5V If=1.25A, Mu=8, 12 watts max)
(10Y uprated to 15 watts, 8Mhz, Vplate max=450VDC)
(DeForest 410 & 510: Ef=7.5V If=1.25A)

10 HYTRON:
---------

Okay, I haven't heard an amp that uses a 10Y tube.  But even so, right off the bat I would consider anyone who says that a particular tube type or amplifier topology "blows away" another to be of dubious authority.
 
Steve

I was actually paraphrasing but suffice it to say he was of the opinion that this is the tube to build an SET around if you are looking at amps using 45s, 2a3s, or 300Bs.

Best,
Ed

[JoshK]

The "10" is supposedly a lovely tube.  There is probably no bigger promoter and experienced user of the tube then Thomas Mayer, aka vinylsaviour.

See his blog http://vinylsavor.blogspot.com/

There are at least 4 different variations on the 10.  There is the 10, 10Y, 801, 801A, from the top of my head.  Note that they 801s have higher dissipation making a 3-5 watt amp instead of a 1watt amp that they 10 limited to. 

One of the challenges with the 10 is the high plate impedance which means you have to have a high primary winding on your output iron.  This means that you have to trade bass away to gain more top end (smaller iron).  This is quite ok in your case as you are using it above 140hz.   I recommend getting iron specifically made for this purpose.  Both Electraprint and Dave Slagle will wind you such. 

The schematic you show would not be my choice of designs.  That is WAY too much gain.  That amp is more suitable for older phono preamps that didn't have much gain.  You can easily accomplish the appropriate gain with only two stages, which is always better than 3 all else being equal. 

There was a buzz surrounding the 10-squared design which uses a 10 to drive a 10(or 801 as it were).  This results in pretty ideal gain structure, maybe a bit light for lower to moderate sensitivity speakers.  One 6SN7 driver stage would yield about 6db more gain.  Essentially just drop the first stage in the above amp. 

[ebag4]

The "10" is supposedly a lovely tube.  There is probably no bigger promoter and experienced user of the tube then Thomas Mayer, aka vinylsaviour.

See his blog http://vinylsavor.blogspot.com/

There are at least 4 different variations on the 10.  There is the 10, 10Y, 801, 801A, from the top of my head.  Note that they 801s have higher dissipation making a 3-5 watt amp instead of a 1watt amp that they 10 limited to. 

One of the challenges with the 10 is the high plate impedance which means you have to have a high primary winding on your output iron.  This means that you have to trade bass away to gain more top end (smaller iron).  This is quite ok in your case as you are using it above 140hz.   I recommend getting iron specifically made for this purpose.  Both Electraprint and Dave Slagle will wind you such. 

The schematic you show would not be my choice of designs.  That is WAY too much gain.  That amp is more suitable for older phono preamps that didn't have much gain.  You can easily accomplish the appropriate gain with only two stages, which is always better than 3 all else being equal. 

There was a buzz surrounding the 10-squared design which uses a 10 to drive a 10(or 801 as it were).  This results in pretty ideal gain structure, maybe a bit light for lower to moderate sensitivity speakers.  One 6SN7 driver stage would yield about 6db more gain.  Essentially just drop the first stage in the above amp.

Josh,
Thanks for your excellent post, this is exactly the kind of feedback I was hoping for.  I will start searching for a better 2 stage schematic. 

Question, I believe the 10Y tube is rated at a higher output than the 10, do you know if the 10Y can get the type of output you are quoting for the 801?

Best,
Ed

[JoshK]

The 10y still have low plate dissipation.  The 801s have higher, so they yield more power.

[JoshK]

According to the data sheet of the 10Y
http://www.mif.pg.gda.pl/homepages/frank/sheets/049/1/10Y.pdf
Plate dissipation is 10w max.  As a rule of thumb, one can assume a SET amp to be about 20% efficient and you want to run a tube at ~80% of its dissipation.  So you can expect somewhere in the ballpark of 1.5-2 watts.  That jives with what I've seen for the 10Y. 

The 801A on the other hand, has a Pd of 20w max.  So about 3-5 watts depending on circuit.
http://www.mif.pg.gda.pl/homepages/frank/sheets/049/8/801A.pdf

[JoshK]

A good thread here about the 10Y:
http://db.audioasylum.com/cgi/m.mpl?forum=tubediy&n=841&highlight=10y+squared

I agree with JLH that you can use a lower primary winding of 5K instead of 8K-10K (more typical) to gain better high freq response while trading away the bass as you are biamping.  You naturally get a bit more power this way too, just worse dampening, which only matters really in the bass.

[ebag4]

Thanks again Josh.  I had seen the thread on AA, in fact it was Larry Moore who recommended the 10 series tubes in the first place. 

I just located an interesting site, GreenValve audio, that has a couple 10 and VT-25 amps listed with schematics, this is one of them:




Here is another:




Of course I wouldn't use the volume control section,I am looking for a power amp only.

With the lowest cost of the 10 series tubes coming at over $200/pair (from what I have seen so far) I would have to think twice about using the 10 drivers for the 10 although I believe you mentioned that that is one of the best directions to go.

I am still taking this all in so any other input is greatly appreiated.

BTW, I have an email into Thomas Mayer, he apparently has kits for the amps he has designed.

Best,
Ed

[JoshK]

I like the design of the first schematic.  The second schematic will be a cheaper amp to build, and not only because of the extra 10's. 

I'd probably modify the second schematic for a 5687 instead of the 417A/5842.  The problem with the 417A is, if you aren't a very experienced designer/builder, and you don't have perfect layout and RF techniques, you are certain to have oscillation. 

Neither of these schematics I'd build as is, because both use too high a primary resistance than what your likely to need.   Talk to Thomas, Dave Slagle and others to get more experienced advice, but that is my take on the subject. 

I fortunately collected the 10s and 801s back when they ran my about $40/tube.  I have enough for my lifetime.

[JoshK]

... although I believe you mentioned that that is one of the best directions to go.

That depends on who you ask.  I've read numerous glowing reviews for Larry Moore 10y-squared amp.  I know Thomas is a huge fan and I know others.   Then there are Jeffrey Jackson and Dave Slagle which don't really care for a 10 driving a 10 because they say it is "too white" or IOW not enough tone. 

I really think the best idea is to gather parts and build your amp on a breadboard before commiting to a design. This way you can experiment until you get the sound you want.  You'll learn a lot too that way.

[ebag4]

I'd probably modify the second schematic for a 5687 instead of the 417A/5842.  The problem with the 417A is, if you aren't a very experienced designer/builder, and you don't have perfect layout and RF techniques, you are certain to have oscillation. 

Josh, you bring up an excellent point and it is one of the reasons I haven't jumped in yet.  I would have never known of the potential for oscillation using that tube and that is my concern, I don't know enough to know what I don't know!   Try to follow that "Logic"..

Good idea breadboarding the amp prior to building it  .

Thanks,
Ed

[shooter]

You have to take your system into consideration on choosing the 10, it is a brighter sounding tube than say a 50,  I prefer the 10 family of tubes on my front horn loaded Rullit 12" field coil, on the other hand the type 50 is preferred on my Lowther Basszilla, my Basszilla is not bright sounding but just has better synergy with the 50, I think that's why Jeffery and Dave demo their Lowther field coil with the globe 50 at last years LSAF, the 50 has beautiful tone, haven't heard the 50 mesh plate though, I am afraid to.

[JoshK]

Josh, you bring up an excellent point and it is one of the reasons I haven't jumped in yet.  I would have never known of the potential for oscillation using that tube and that is my concern, I don't know enough to know what I don't know!   Try to follow that "Logic"..

Good idea breadboarding the amp prior to building it  .

Thanks,
Ed

Well, I was at that point myself not too long ago.  Don't be intimidated but be humble.  Try to go with a proven design (sometimes hard) or get someone like Thomas to offer you a kit or a design he knows. 

BTW, the 417A is a high GM tube (meaning high gain AND high dissipation (i.e. current)) and like all high GM tubes are prone to oscillation if you don't take lots of care in grid stoppers, etc.

[GBB]

I only found one complete schematic on line and I wanted to hear from those of you in the know what you think of this design, so please comment to your hearts content:




I would also like to hear from those who have heard this amp, what did you think of the sound? 

Ed,
The schematic that you show in the 1st post is the Sun Audio VT-25.  You can read more about this amp here: http://www2.big.or.jp/~sunaudio/sv/svvt25_e.html

It's a pretty basic single ended amp that sounds quite good.  It's got lots of gain and wouldn't need the Dodd tube buffer.  I have one that I picked up as a kit in Japan 8 years ago and built myself.  Back then the price was about 1/2 what they charge now - a combination of the shrinking dollar and the rising cost of materials. 
The amp has great tone and sounds wonderful driving single driver speakers.  I've also used it in a biamped horn system with the VT-25 driving the compressions drivers in an Edgarhorn system for frequencies >500hz and it sounds great there as well.

I do agree with Josh that if I were going to the trouble of building an amp from scratch then I'd go for something even fancier such as the 10:10 amp from Larry Moore or the amps from Thomas Mayer.  But even the simple amp shown here will sound really good when matched with speakers with sufficient sensitivity.  The Sun kit uses good iron and that's more than half the battle.

---Gary

[ebag4]

Thanks Josh, I have decided that for my first stab at a Tube amp I will be going with a kit or some sort.

Gary, thanks for the link.  At 2025.00 for the kit I think I will be looking elsewhere.

FWIW, It has been recommended that for what I want to spend on this project that I look at tubes other than the 10Y as it is apparently more expensive to implement properly than some of the more typical offerings.  I believe this to be good advise and I will be looking elsewhere, most likely back to where I started, possible a 6a3/300B Getsetgo kit or still possibly a Tubelab SimpleSe.  I am also considering a couple of completed DIY kit builds currently on Agon.

Best,
Ed

[Jmillerdoc]

Ed,
Hi, I am a registered user at DIYaudio and the PE forum for many years and just found your post so I had to newly register here to contact you so....no PMs for a while.....
I was thinking of building the same amp as I have several of these tubes military grade NOS sitting on the shelf, the 10y variant.  I also have one or two of the 801a variant as well.  If you ever get around to building this amp and want to buy a couple of these tubes I would be glad to sell off two of them at a reasonable price, better the Fleabay and other sources that are selling them at ungodly prices.  You can contact me by email or PM at the diyaudio forum under the same user name if you like.

I have been reviewing these circuits and believe with little modification many of the 45 SET designs out there will accommodate this tube very nicely, I think I will start with a amp I already have sitting on the shelf and wire it up for this tube...will report back here with my results when it's complete.
Cheers and good luck with your build!
Jeff

[anubisgrau]

10Y (or 801A) - FWIW - are not bright sounding tubes
i'm using them in one of the most clever designs i came across - fully direct coupled, A2
so only crystal clear like a fresh mountain creek water
no artificial flavouring or EQ given by a coupling cap
if they sound bright than they are not fed properly by a input/driver stage (E180F in mine)
1/2 6SN7 - or correctly written 6J5 is a common choice as it looks safe on the paper but very wrong sounding, the driver really limits the possibilities of a great tube
my 4 cents...

[ebag4]

Thanks for the feedback guys, much appreciated. 

FWIW, I have built a 2a3 amp since I started this thread, it is my first taste of SET DHT and I am loving it. 

I was communicating with some of the 801/10Y experts and was led to believe that to impliment these tubes correctly I would have to up my budget considerably.  What I didn't know at that time is that by the time I added in upgrades to the 2a3 amp I killed my budget anyway  !

Best,
Ed