Topic: desktop t00bes

[Tim]

looks fun,


http://www.tonepublications.com/spotlight/the-miniwatt-amplifier-take-a-fresh-look-at-hifi/

http://sixmoons.com/audioreviews/miniwatt/miniwatt.html

[cheshirecat]

Interesting... I wonder where they stuffed the power tranny...

[bgalizio]

Wish they had a tube cage for it - protect from some of the tube heat.

[cheshirecat]

I'd suspect it doesn't get all that hot, mini tubes don't typically generate the kind of heat that octals or other large tubes do.

[mfrench]

I'm intrigued, but I do not know the first thing about t00bes.
The price of this has me all the more intrigued in trying this out for a bedroom system.
All that would be necessary is a preamp front end, correct?

good enough for a t00b n00b introductory system?

[bgalizio]

I'm thinking about the upcoming kids when I'm asking about heat issues. Not sure if I want exposed tubes in a very kid-ready area. I already put a tube cage on the main system, which definitely helps the heat, even if you place your palm on the cage.

I'm intrigued, but I do not know the first thing about t00bes.
The price of this has me all the more intrigued in trying this out for a bedroom system.
All that would be necessary is a preamp front end, correct?

good enough for a t00b n00b introductory system?

I don't think this needs a preamp - it appears to be an integrated amp.

Anyone know if these tube types/sizes are readily available?

[mfrench]

it does not appear to be integrated. It only has a pair of inputs on the back, and no source switches.  It does have the volume control, which is a bit odd.

[bgalizio]

it does not appear to be integrated. It only has a pair of inputs on the back, and no source switches.  It does have the volume control, which is a bit odd.

That just means it's only 1 source at a time.

[mfrench]

as stated: t00b n00b.
I'm so used to the classic pre->amp combo, or, all-in-one multi-source integrated, that I went into brain lock.
thanks for the re-expansion of thought process.

[Brian Skalinder]

Anyone know if these tube types/sizes are readily available?

Don't know offhand, but you might check these places for starters:  http://taperssection.com/index.php?topic=49078.msg636937#msg636937

[Tim]

they shouldn't be too hard to find at all and probably fairly inexpensive ($10 a tube or so). they'll also last a long time so if you find a set you like you should be good for a number of years.

[unclelouie]

Nice find! This looks promising.

I think a 6J1 is a pre-amp tube and a 6P1 a power tube. I've never heard them but have read that they're pretty cheap (hense the lack of a roll cage), so upgrading the tubes after purchase would probably be wise. Good tubes will last for many hundreds of hours before needing replacement - I've got a dozen or so zenith and raytheon tubes still working fine in vintage AM radios after 30 years of casual use (although I burn through 6L6's in my guitar amp like you can't imagine).

Considering the amp is only 2.5W per channel, I wouldn't worry about heat.

[mfrench]

current review, by user:
http://www.lencoheaven.net/forum/index.php?topic=1238.0

[Chilly Brioschi]

overpriced & underpowered

[mfrench]

this is where I get confused in t00bes.
Why too little?
There were several comments made at lencoheaven about this thing being about 2x too much power. There is one particular user over there that has amplification that amounts to below single wattage.

[Brian Skalinder]

overpriced & underpowered

What would you recommend as a better price/power value in the same price range?

[Tim]

moke - decent primer here, http://en.wikipedia.org/wiki/Single-ended_triode

and more than you could ever want to know here, http://www.audioasylum.com/forums/set/bbs.html

[mfrench]

thanks, Tim
I've got about a month of 'cipherin time before that makes any sense.

I'd like to try the tube sound, without breaking the budget. This thing strikes me as being in that bracket, obviously.
I'd probably put it in my bedroom system, and have it feed a pair of what are now becoming vintage speakers (late 70's, early 80's), the ADS L-10 bookshelf speakers (two way, w/ silk dome tweeter, probably a 50hz bottom end, by ear. They carry a cello well ).
I cannot find the specs on them, but have found other ADS specs from the same era, and they're all at 89db efficient. They are not rated for high wattage, and my 120w David Hafler SS amp (60w side) can clip them if I'm not careful.
The one review that I found online suggested that the infamous 15w t-amp was making them sing (ADS L-10's).
This tube amp has already garnered the same reputation as the little t-amp for sonics-vs-dollars reviews. So I'm very intrigued.

[cheshirecat]

If you like the Hafler SS sound, you might be interested in picking up a used Dynaco amp, check out the ST-70 which is a 35wpc stereo amp.  A PAS2 or PAS3 (same actual preamp just different faceplate) would match up nicely with them.  Hafler did much of the design work for the original Dyanco gear and it is still very well regarded.  They made some 300,000 ST-70s so while it's a nice performing amp, it is still very cost effective since they were so plentiful.  You can probably pickup a ST70/PAS3 pair for around 600 or 700 fully restored (since I know you're a tinkerer, you might be interested in picking up an unrestored set which could be had for the 3-400 range and do it yourself.  Parts are very plentiful these days and the ST-70 is relatively straightforward to restore, PAS a little tougher, though there are a few sources for new PCBs these days which makes it go a lot faster.

[mfrench]

thank you!
Yeah, I've been known to pitter around with stuff, with mixed results :)
At the point that I'm at with tubes - knowing nothing, I guess I'd prefer to find something that will work right out of the box, and allow me time to learn it before I try anything too tricky.

Regarding the Hafler.
I do like it.  I bought it new in '86/'87ish. I'd had the ADS speakers for a year at that point, and had been running them from a less powerful amplifier (which died). So I bought the Hafler stuff as part of a mega-system that was being installed in a house that we were building. They had probably a dozen amps just like mine that they installed, so I asked them to include me in with one more on the mass purchase.
Its lasted now for nearly 25 years. The few issues that I've had with them (the preamp and amp, both haflers) were easily resolved by myself with a touch of solder here or there. The amp has never caused any problems; the preamp has fairly weak rca hookups, and has caused problems occasionally, requiring resoldering of the rca jacks to the pcb.

at any rate,.. thanks again for the information. I've been perusing eBay for leads.

[Chilly Brioschi]

overpriced & underpowered

What would you recommend as a better price/power value in the same price range?

It would have to be a "project" amp.

REMEMBER tubes use HIGH D.C. Voltages which are LETHAL if mishandled.
Begin any project by reviewing high-voltage safety precautions and by doing a thorough inspection of your tools and work area.   
I've seen an experienced vacuum tube tech literally thrown across the room by touching a loose B+ wire while brushing against a grounded mic. He was shaken, but not killed, but it was all too close of a call.

About power levels, anything below 30 to 40 watts will require exceptionally efficient speakers to sound good, not distort, and provide reasonable bass.

Coming from a Plinius, I would consider 65 to 100 watts, minimum.

BTW, my theory on the "sweetness" of low-powered SET amps is that they have a small, but discernible amount of odd-order THD that enhances the sound in colorful ways.
Some vocals and music "sing" with it (aka Nora Jones) other music gets muddied or clouded.

The N0rh SE-9 ain't bad, but is also under powered, imho.

[Brian Skalinder]

It would have to be a "project" amp.

I was afraid you were going to say that.  Trying to figure out how to get back into tubes inexpensively for my office playback.  Thanks!

[Chilly Brioschi]

It would have to be a "project" amp.

I was afraid you were going to say that.  Trying to figure out how to get back into tubes inexpensively for my office playback.  Thanks!

Office? Do you mean as in a respectable office with others in it, or office like mine, where I find myself with he run of the place after 10 A.M. and get to crank the ol' victrola?   

If you want a sweet desktop sound, without the need for much below 150Hz, you can find it with efficient speakers and a smaller tube amp.
I just feel that the advantage of a tube amp diminishes as the volume goes down, and the subtleties in soundscape get overwhelmed with ringing phones, nail-clipper ticks, and rustling paper. Are you able to get a reasonable sound field  at the office?

All of this talk of 2 watt tube amps and friction-drive turntables makes me feel as though there is some weird backlash going on against the now-realized vision of practical hi-res digital audio.
A pair of good speakers, with a good quality SS amp fed by 24/96 FLAC and a good D/A can be a wondrous thing.

[Brian Skalinder]

Office?

I should have said home office.  So I do have the run of the place.  But it's quite small, and not an ideal listening space.  I currently have a quite good DAC (Mytek Stereo96) feeding active monitors (Alesis M1 MKII).  I miss the variety of tube rolling and the sound I eventually found using tubes I liked with my Audio Experiences Symphonies preamp + SS amp, but don't want the bulk.  Not sure how the active monitors would fit into things, now.  I guess I could simply add a tube pre between my DAC and monitors.  Hmmm...

[rokpunk]

Office?

I should have said home office.  So I do have the run of the place.  But it's quite small, and not an ideal listening space.  I currently have a quite good DAC (Mytek Stereo96) feeding active monitors (Alesis M1 MKII).  I miss the variety of tube rolling and the sound I eventually found using tubes I liked with my Audio Experiences Symphonies preamp + SS amp, but don't want the bulk.  Not sure how the active monitors would fit into things, now.  I guess I could simply add a tube pre between my DAC and monitors.  Hmmm...

I think replacing your Alesis monitors with something a bit more high end is a better solution than adding a tube pre. YMMV.

[som]

There is quite a bit of discussion about the MiniWatt on the Hornshoppe forum, and people are *raving* about it. Quite a bit of info, including tube rolling suggestions and tweaks.

Don't know if you need to register to see it, but here's a link:

http://www.audiophiletalk.com/cgi-bin/yabb2/YaBB.pl?num=1248108891

[Brian Skalinder]

I think replacing your Alesis monitors with something a bit more high end is a better solution than adding a tube pre. YMMV.

The thought's crossed my mind.  I still have a pair of VR-1s hanging out in the basement needing a home.  They definitely sound better to my ears than the monitors.  And I'd forgotten about the VR-1s until just now.  I'll replace the monitors with the VR-1s if I go with a tube pre/amp.

[Chilly Brioschi]

I think replacing your Alesis monitors with something a bit more high end is a better solution than adding a tube pre. YMMV.

The thought's crossed my mind.  I still have a pair of VR-1s hanging out in the basement needing a home.  They definitely sound better to my ears than the monitors.  And I'd forgotten about the VR-1s until just now.  I'll replace the monitors with the VR-1s if I go with a tube pre/amp.

http://www.soundstage.com/revequip/vonschweikert_vr1.htm

"The VR-1 speaker disperses its sound best without grilles, so preferably you’ll use it that way for serious listening. But if you need to use the snap-on grilles, they have been acoustically treated with foam around the tweeter area to help soak up some of the high frequencies, so they don’t get bounced around by the grille’s edges.

The VR-1’s impedance is said to be a nominal 8 ohms with a 4-ohm minimum point in the bass. The sensitivity with 1W input is 90dB "in-room." Bass is quoted, again, in real-room conditions, where it’s said to extend to about 40Hz. VSA offers different power requirements depending on your use of tubes or solid state. For solid-state amps, they say 50 to 100 watts; for tube amps they say to use 10 to 100 watts."

I'd say 20wpc in tube minimum...

Lower power = higher distortion, for good or ill.

[mfrench]

I think replacing your Alesis monitors with something a bit more high end is a better solution than adding a tube pre. YMMV.

The thought's crossed my mind.  I still have a pair of VR-1s hanging out in the basement needing a home.  They definitely sound better to my ears than the monitors.  And I'd forgotten about the VR-1s until just now.  I'll replace the monitors with the VR-1s if I go with a tube pre/amp.

http://www.soundstage.com/revequip/vonschweikert_vr1.htm

"The VR-1 speaker disperses its sound best without grilles, so preferably you’ll use it that way for serious listening. But if you need to use the snap-on grilles, they have been acoustically treated with foam around the tweeter area to help soak up some of the high frequencies, so they don’t get bounced around by the grille’s edges.

The VR-1’s impedance is said to be a nominal 8 ohms with a 4-ohm minimum point in the bass. The sensitivity with 1W input is 90dB "in-room." Bass is quoted, again, in real-room conditions, where it’s said to extend to about 40Hz. VSA offers different power requirements depending on your use of tubes or solid state. For solid-state amps, they say 50 to 100 watts; for tube amps they say to use 10 to 100 watts."

I'd say 20wpc in tube minimum...

Lower power = higher distortion, for good or ill.

Bob,

Can this also be assumed about my Soliloquys?
I have the 6.3's, which are floor standers, and 90dB efficient. They're said to be tube friendly, and have wattage needs of 10w -> 400w
I'm presently driving them with the Plinius 175w SS amp, which makes them sing at the first perceptible watt. They sound gorgeous at that point.

What I've been theorizing about, is purchasing a DIY tube kit; either the Dynaco st-70 kit, or, the Dynaco st-120 kit, both from Bob Latino.
They are both based on all new parts, and a stainless chassis (the originals were chromed steel).
I'm totally comfortable in my soldering skills, and am not slightly intimidated in building my own amp (actually excited about it).

Given this, would I be better having more wattage from tubes, such as the 120w/60w-side?
The cost diff between the st-70 kit and the st-120 kit is not that far apart, with the bulk$ of the purchase being the expense of the stainless chassis.
My gut tells me more is better, but I do not know tubes, so I thank you, or anyone for the mentoring.

[Jimna]

if you go the DIY route with the amp please post pics im curious how hard it would be, and if a layman(me) could do it.

[mfrench]

if you go the DIY route with the amp please post pics im curious how hard it would be, and if a layman(me) could do it.

I've read they're well supported by the "designer" kit creator, Bob Latino. They're also very well documented with directions, and supporting images of each step. The most of it being soldering, and following directions.
By the looks of the underside of the amps, it appears to be built in "layers" or by logical sequence that creates a nice tidy finish. I've been impressed in my reading.
How well do you solder?

There is a fair amount online about them.
Let me find the links again, I'll be right back,.....

I'm back, with links;
st-120 kit - ebay
st-70 kit - ebay

additional:
http://picasaweb.google.com/arnoldmatthews72/ST120Amplifier#

dynaco kit build steps

[Jimna]

wow, might be over my head and solder abilities.  thanks for the links.


im still confused how this would compare at 60wpc to my 200wpc solidstate amp now.  i always thought bigger was better as long as the speakers can take it.

[mfrench]

I can't answer the 'compare' question.

You'd probably be pretty good at soldering after building it! :)

[Tim]

moke you can drive those soliloquoys with 30wpc pretty well.

[mfrench]

thanks, Tim
I figured there is no better way to learn them than to absorb myself in it.
Learning the circuits and pathways via building it would be a great way for me to learn it.

I was all but going to try them, finally, when I bought my Plinius; but it became available before I made a decision, and I knew what it would sound like with the speakers,... yadda, yadda,... yammer yammer.
8 years later, I'm getting the urge to try something different (earth moves slightly).
I've heard so much gushing for so many years regarding tubes, I think I need to finally give 'em a go.

I'll need to tune up my old hafler preamp (dh110) for a front end, until I can do a better preamp.
I found a tuneup kit for the dh110 on eBay, with upgraded capacitors, that is pretty affordable. I might warm up with that project before I commit to the major one.

[Chilly Brioschi]

Bob,

Can this also be assumed about my Soliloquys?
I have the 6.3's, which are floor standers, and 90dB efficient. They're said to be tube friendly, and have wattage needs of 10w -> 400w
I'm presently driving them with the Plinius 175w SS amp, which makes them sing at the first perceptible watt. They sound gorgeous at that point.

What I've been theorizing about, is purchasing a DIY tube kit; either the Dynaco st-70 kit, or, the Dynaco st-120 kit, both from Bob Latino.
They are both based on all new parts, and a stainless chassis (the originals were chromed steel).
I'm totally comfortable in my soldering skills, and am not slightly intimidated in building my own amp (actually excited about it).

Given this, would I be better having more wattage from tubes, such as the 120w/60w-side?
The cost diff between the st-70 kit and the st-120 kit is not that far apart, with the bulk$ of the purchase being the expense of the stainless chassis.
My gut tells me more is better, but I do not know tubes, so I thank you, or anyone for the mentoring.

Remember that this is just one man's opinion...

The Soliloquys are just a tad more efficient than the VR-1's which, due in part to their smaller size, like a bit more power.

I think that the difference between an ST-70 and ST-120 amp would be more of versatility and preference of sound.
6550s are cleaner, punchier, and 6L6's sweeter, warmer as a rule, depending on what tubes you roll in.

Do not be misled, an ST-70 will gleefully power the VR-1s or Soliloquys in most household rooms.
35 tube watts per channel is formidable.
There are some speakers that will make the ST-70 seems anemic, and first to come to mind was the early Bose ceiling-hanger-jobber, was it a 901?

An ST-120 will sound less "tubey", but will be there for bigger spaces and future (outlandish) speaker purchases. An ST-70 is sweet and well-loved by many tube gurus.

BTW, I am using a powered sub with the VR-1s, which takes a big load off the amp anyhow.

A sidenote:
There are some used Prima Lunas and JoLidas out there in the price range of those Dynaclones.
The Dyna circuits are well covered on the 'Net and their parts may live-on forever.
If they follow the Dyna/Heathkit style, they shouldn't be all too hard to assemble.

Any time someone tells me that they are digging in to a tube chassis I always remind them of this:

Disclaimer:  Vacuum tube circuits operate at high voltages.  Contact with circuit components or wiring may cause serious injury or death.  High voltages may remain present in tube equipment for a long time, even if the circuit is turned off or disconnected from the mains voltage.  Do not attempt to repair or build vacuum  tube circuits unless you fully understand the safety principles and possess the technical craft required for dealing with high voltage mains-operated equipment.

I can't find any good tube safety links on the web this morning, but they would be well posted in this thread for posterity...

[mfrench]

thanks, Bob.
This isn't anything that's going to happen too quickly. I need to move a couple of pieces of gear first to cover the kit.
I'm familiar with a guy in Minnesota that is a tube ace, and repair/analysis expert. I'll see if he can find anything, and what he says about this as well.
So, in the meantime I'll read up on the safety factors, and reading in general.

[Tim]

Check this guy out too Moke,
http://sites.google.com/site/niteshadeaudio/about-us/niteshade-news
he's super knowledgeable and always up for talking shop.

and this is another shop worth looking at, they sell some kits
http://hollowstate.netfirms.com/

their Line 2 preamp is very highly regarded

[anodyne33]

I can't find any good tube safety links on the web this morning, but they would be well posted in this thread for posterity...

Pfft! Just stick a screwdriver between the terminals of all your power caps before you dig in.







/sarcasm

[mfrench]

weren't you supposed to lick test them first?

[Tim]

just like a 9v battery

[cheshirecat]

wow, might be over my head and solder abilities.  thanks for the links.


im still confused how this would compare at 60wpc to my 200wpc solidstate amp now.  i always thought bigger was better as long as the speakers can take it.

I've built 4 or 5 ST-70s over the last few years and can definately point you in the right direction.

Just a few points that come to mind...
There are literally 100,000s of ST-70s out there, so I would definately point you in the direction of an ST-70 that you can then change to use 6L6 or 6550s for power tubes.  There will be much more info out there for 'basic' ST-70s.  There are litearlly dozens of well respected mods out there and lots of things you can try once you get things up and running (probably 2 weekends worth of work to put everything together and get it burned in/tested).

I think you'll be surprised what 35wpc will deliver via tubes.

I probably have some pictures of the ST70 rebuild process that I can publish.  No major pitfalls come to mind, the ST-70s have a pretty straightforward desing, and a lot of the minute details are handled on the PC board.

[Chilly Brioschi]

weren't you supposed to lick test them first?

Which explains the domestication of cats....     
 

[cheshirecat]

Some St70 pictures, I have to go back and find the starting pictures, but basically this one started with a chassis that was rather pitted on top so it was shot with hammered finish paint and received some new transformers.

At any rate, there isn't too much going on under the hood of these, not too hard to rebuild one, parts are readily available.

[audBall]

^ Newb question.  What are those two white sockets on either side of the inputs for?  Tubes?

[cheshirecat]

Dynaco initially had preamps called the PAM-1 (I'm guessing Pre Amp Mono version 1) which used the sockets on the front to pass the signal (instead of the RCAs) and for power.  After the invention of the PAS2 (Pre Amp Stereo version 2?) you would use the RCAs and that was pretty much that.

You also use the octal sockets on the front to measure the bias voltage and keep it in check.

[audBall]

Ahhh....gotcha.  Thanks.

[Chilly Brioschi]

Dynaco initially had preamps called the PAM-1 (I'm guessing Pre Amp Mono version 1) which used the sockets on the front to pass the signal (instead of the RCAs) and for power.  After the invention of the PAS2 (Pre Amp Stereo version 2?) you would use the RCAs and that was pretty much that.

You also use the octal sockets on the front to measure the bias voltage and keep it in check.

Pre-Amplifier Module One,  if my aged memory cells can be trusted...

Used a selenium-stack rectifier  (pffft!)

A pair gave true dual-volume control stereo, without that balance-control bleed that was debated heatedly.

[cheshirecat]

Dynaco initially had preamps called the PAM-1 (I'm guessing Pre Amp Mono version 1) which used the sockets on the front to pass the signal (instead of the RCAs) and for power.  After the invention of the PAS2 (Pre Amp Stereo version 2?) you would use the RCAs and that was pretty much that.

You also use the octal sockets on the front to measure the bias voltage and keep it in check.

Pre-Amplifier Module One,  if my aged memory cells can be trusted...

Used a selenium-stack rectifier  (pffft!)

A pair gave true dual-volume control stereo, without that balance-control bleed that was debated heatedly.

Yep, that's the one... the selenium rectifiers are easily replaced with a 6 cent diode these days.

[popskull]

Heres a nice kit if your on a budget and have some basic soldering skills and want to play with tubes for under $200......not as much bling as the Mini-Watt, but it is 8 watts per channel



http://www.tubesandmore.com/scripts/foxweb.dll/moreinfo@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?item=K-502