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What is a good starter Tube Amp?


Bossman

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13 hours ago, Calman said:

Here's a pic of the  Scott amp I'm considering. The bridge rectifier has been replaced but from the attached picture of the underside I can't tell if those white ceracaps are the originals and what further refurbishment is needed for reliability?

I'm hoping someone here can make more sense of the picture.

I'm new to the Forum  and if there's a more appropriate place  for such Qs please chime in.  

The Scott needs a lot more work.  All of the Ceracaps must be replaced in addition to the original electrolytic sections which are still wired in.  Since you are in CA, I'd get hold of Ken at AEA Audio in San Mateo.  He not only does professional restorations, but also sells fully restored amps as well (his cosmetic restorations are the best I've ever seen):

 

http://aeaaudio.com/

 

Forum member Joe ("jhewes") recently had Ken restore a Scott amp and was very satisfied.  I'd send Joe a PM and he can tell you all about it himself.

 

Schu, Hammond transformers are excellent in my opinion.  I've used their power/output xfmrs and chokes exclusively for more years than I can remember.  As far as builders who claim that they design their own transformers, I'd be very skeptical as most are probably doing nothing more than specifying the primary impedance.  Transformer design is so complex an area, requiring an engineering level knowledge of so many different disciplines, that it's an impossible task unless properly educated.  When I worked for the industrial power supply company, which designed and made all transformers on premises, there was a whole engineering team with combined expertise in all the needed areas doing the design work.

 

As to comparing the cost of Deckert's SETs with that of some push-pull ultralinear amps, we're talking about apples and oranges here.  You need to decide what type of design you want and then compare price within that one category.

 

Maynard 

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On 11/10/2016 at 6:52 AM, NOSValves said:

 Contradictions!  One clarification. That is not a SET amplifier. SET stands for Single, Ended, Triode. The EL34 is a Pentode type tube. Don't fret about it people make the mistake with the amplifier type all the time.

NOSValves, thanks for the clarification. I had an idea that even after all the research that I done I would still screw something up.. Although its not a SET, it still sounds good. Now I will be looking for a single ended amp that used EL84's as power tubes.. Now that would be a true SET amp correct? This little amp sounds amazing with my cornscala 3 way horn speakers (E-140, K-55V dual phase plug, and B&C DE-10)! Can't imagine how well a true SET would sound. On a side note I am selling my Emotiva UPA-200 amplifier that is in like new condition with original packaging in order to fund my next tube amp. Thanks again to all for all this very helpfull info!!

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1 hour ago, Bossman said:

Now I will be looking for a single ended amp that used EL84's as power tubes.. Now that would be a true SET amp correct?

 

I suppose you could call it a SET amplifier if the pentode EL84 tubes are strapped in triode...but in my honest opinion it's a triode connected single-ended pentode amplifier.

Like mentioned above by William, pentodes are five element devices. They have a input grid, a suppressor grid, a cathode (most generally indirectly heated, a wire in a metal sleeve/tube) a screen grid, and the plate or anode.

Some tube data sheets for a given pentode will show data for the pentode connected in triode...6V6 is a good example. They connect the screen grid to the plate with a lower value resistor, so the screen grid won't exceed the plate's current/voltage during use...something like that...

 

A triode tube has only three elements, a input grid, a filament, (which is also the cathode with a triode tube) and the plate.

So a example of a single-ended triode amplifier using actual triodes would be an amp with 300B, 2A3, or 45. There are larger transmitting triodes as well which use rather high plate voltages.

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20 hours ago, mike stehr said:

A triode tube has only three elements, a input grid, a filament, (which is also the cathode with a triode tube) and the plate.

So a example of a single-ended triode amplifier using actual triodes would be an amp with 300B, 2A3, or 45. There are larger transmitting triodes as well which use rather high plate voltages.

Mike, what are your thoughts on idht triodes (like those used for vertical amplifiers in televisions).  To me, they are still true triodes due to a lack of a screen or suppressor.

 

Maynard

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13 hours ago, tube fanatic said:

Mike, what are your thoughts on idht triodes (like those used for vertical amplifiers in televisions).  To me, they are still true triodes due to a lack of a screen or suppressor.

 

Maynard

 

Well I'm definitely sold on the dissimilar dual triode 6EM7/6EA7. Indirectly heated and can drive itself, or can be used for AF/preamp type stages.

To be honest, I've never used any idht triode output tubes in any project. If I recall, those type of tubes would be 6A3? Or 6B4G...

 

When the retired EE friend Dan lived up here, we used to ponder over a push-pull amplifier using a 6 volt indirectly heated triode like 6B4G or others.

Mostly because the type of tube being a bit easier to find or bit less expensive than a 2A3. Of course a output triode tube with no filament growl can't be a bad thing to me, along with less concern with heater/filament wiring layout.

 

Mike

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Mike, the 6B4/6A3 are DHTs also.  Just about all of the old TV vertical deflection amplifier types are IDHTs and are suitable for audio work.  For example, there's the 6BL7, 6BX7, 6CK4, 6CY7 (I'm about to start working on a project using this tube in fact), 6FD7, and 12B4 off the top of my head.  It's usually possible to find operating parameters which keep the distortion very low so, for those who can live with low power, they are a nice choice. 

 

Maynard

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  • 2 years later...

Resurrecting this thread. I'm considering buying a integrated tube amp to run my heresy decorators just to try something different. I have a recommendation for the Scott 299 series. Can anyone recommend other tube integrated amps for around the same coin?

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I used to have one of these and liked it a lot.  Mark Deneen had nice things to say about it also.  One concern is that it uses a pair of tubes (I don't recall which ones) that are now unobtainium.  There is a modification that can permit the substitution of more readily available tubes.  I traded mine for servicing done to h/k x30 receivers.

 

The following link is to an eBay listing with which I have no affiliation.

 

https://www.ebay.com/itm/Dynaco-SCA-35-Amplifier-Serviced-Tubes-included-Original-box/264171750674?hash=item3d81dd0512:g:zB8AAOSwiOZcI~4H:rk:1:pf:0

 

@rockhound

 

SCA-35.jpg

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None of that translates to Unobtanium.  Lots of good tubes are no longer produced, and are somewhat expensive.   

 

Brent Jessee:  http://www.audiotubes.com/audtube.htm

 

7199 RCA made

New old stock original box and white box. These are great sounding 1960s USA tubes, and hard to find! The RCA are especially rare and fine sounding. Some made for other brands like Dynaco, but are genuine RCA with the stop sign logo. MUCH better than the Russian crap currently available. Dynaco amp users, stock up!

$59.00

In Stock

7199 other major USA brands, NOS

New old stock original box and white box. These are great sounding 1960s USA tubes, (GE, Sylvania, etc.) and hard to find! MUCH better than the Russian crap currently available. Dynaco amp users, stock up!

$39.00

in Stock

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Before considering a vintage amp that relies on discontinued tubes @rockhound you might want to read the article linked in this thread started by Michael @Schu.

 

If the “facts” in the linked article are accurate, the wisdom of paying high prices for NOS tubes is questionable.  In any event, not something I would recommend to someone asking for suggestions regarding, “ . . . a good starter tube amp.”

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On 12/25/2015 at 5:42 PM, Bossman said:

Hi everyone. I am looking to buy my first tube amplifier to pair with Klipsch speakers. Is it possible to get a decent tube amp under five hundred bucks? Some of the speakers it would be powering are Cornwall II's, Heresys, Forte II's and RF-3's. I listen to a wide variety of music including hip-hop, and I like a decent amount of bass, so Im not sure if an extremely low powered amp would be enough. Any suggestions for a good budget amp? Also how important is it to use a Tube Pre-Amp with a tube power amp? Any advise would be greatly appreciated.

 

With the speakers you have and the music you like consider a 30 watt integrated amp. If you are new to tubes I would pass on a vintage amp. Look at Jolida or Prima Luna. You are close to Upscale Audio near LA. I'd go visit them for a demo. It would be time well spent.

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  • 4 months later...
On 6/14/2019 at 1:02 AM, Ult1mat3X said:

Roland Cube 10gx for metal or Fender Mustang I for clean

 

And you are speaking of amplifiers for generating music, not reproducing music...

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