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Dynaco tube amp and preamp questions

ChopperCharles

Standard Member
I'm about to buy a Dynaco Stereo 70 tube amplifier for a home audio system. I'm going to attach a Sony CD changer to it.... circa 1996 or so. So my questions are... are the CD player's outputs at line level? Can I use a simple volume control in series with the CD player, or must I actually buy a preamp?

Thanks.

Charles.
 

alexs2

Distinguished Member
I'm about to buy a Dynaco Stereo 70 tube amplifier for a home audio system. I'm going to attach a Sony CD changer to it.... circa 1996 or so. So my questions are... are the CD player's outputs at line level? Can I use a simple volume control in series with the CD player, or must I actually buy a preamp?

Thanks.

Charles.

The CD player should have a peak output level of 2V...some run slightly higher,but that is the standard.

You could use a passive preamp(basically an attenuator) between the CD player and power amp,and I've done this with mine at times.

The cheapest decent one is the Creek passive at about £250,and from there the costs rise quite sharply to the Audio Synthesis at about £600,and beyond.

As I'm sure you know,the Dynaco was one of the most popular tubed amps of all time,and a very decent one as well....it would deserve a decent passive if that's your choice,and cheap ones can be quite poor.
 

ChopperCharles

Standard Member
What is a passive preamp? I'm new to tubes and old tech... all the solid state amps I've had have had the volume controls and everything right on them... the Dynaco doesn't though.

Can I run the CD player connected directly to the Dynaco, with a home-built volume control in line between them? Or does the Dynaco need more power on the inputs than regular line level?

Thanks.

Charles.
 

malcolmk

Active Member
Or does the Dynaco need more power on the inputs than regular line level?
I owned a Dynaco amp 40 years ago and a fading memory says that it needed a very large input for full output, which the matching preamp supplied; so I was worried about yours on that score too. However Googling around suggests more recent Dynaco amps need less than 2volts for full output.

One amp I owned needed 11 volts for full output and it was quite difficult to find a preamp which would deliver that. A Nakamichi did the trick. It is now packed away, unlikely to be used again. :(
 

alexs2

Distinguished Member
What is a passive preamp? I'm new to tubes and old tech... all the solid state amps I've had have had the volume controls and everything right on them... the Dynaco doesn't though.

Can I run the CD player connected directly to the Dynaco, with a home-built volume control in line between them? Or does the Dynaco need more power on the inputs than regular line level?

Thanks.

Charles.

I think it's worth checking out the age of the amp as the post above points out.

If it's one of the newer models,and the input sensitivity is 2V or less for full output,then you can use a passive attenuator such as this..

http://www.creekaudio.co.uk/main_product.asp?prolook=obh22#Scene_2

....To control the input level.

If not,it is likely that you will need a traditional active preamp to allow you to boost the signal adequately.
 

ChopperCharles

Standard Member
The more I'm thinking about it, the more the chinese tube amps are sounding like a better financial investment. The Yaqin 100B is reviewed well on audiophile.com...

Charles.
 

alexs2

Distinguished Member
The more I'm thinking about it, the more the chinese tube amps are sounding like a better financial investment. The Yaqin 100B is reviewed well on audiophile.com...

Charles.


The chinese amps are cheaper,but not neccesarily a better investment in terms of return when/if you sell.

Also you have to factor in things like grey imports.....any amp imported outside of the dealer network will be much cheaper,but will have only a return-to-base guarantee if it fails.

Generally,they are well made,good sounding,and reliable,and do offer superb value,but there are a few things to consider first.
 

ChopperCharles

Standard Member
The chinese amps are cheaper,but not neccesarily a better investment in terms of return when/if you sell.

Also you have to factor in things like grey imports.....any amp imported outside of the dealer network will be much cheaper,but will have only a return-to-base guarantee if it fails.

Generally,they are well made,good sounding,and reliable,and do offer superb value,but there are a few things to consider first.

What other things should I consider? I'm not really planning on ever selling the amp, and there's a dealer in Canada that offers a full 1 year warranty and another 2 years of free labor.

Really I just want a nice looking, decent sounding tube amp as a centerpiece to my living room.

Charles.
Charles.
 

alexs2

Distinguished Member
What other things should I consider? I'm not really planning on ever selling the amp, and there's a dealer in Canada that offers a full 1 year warranty and another 2 years of free labor.

Really I just want a nice looking, decent sounding tube amp as a centerpiece to my living room.

Charles.
Charles.


If you have that level of backup from your dealer,you really shouldnt have any worries.

Most modern tube amps are reliable and sound pretty good,even at the cheaper end of the market.

What you do need to think about is how much power you want....single ended designs begin with 2A3 tubes,capable of about 3W per tube at best,and the next up is the famous 300B,which will produce about 8-10W in this form.

The real power comes from 211 or 845 tubes,and whilst the amps are costly,the tubes do sound superb.

In push-pull form,power output rises dramatically,and costs come down.

KT66/KT88/EL34 etc desgins are common and most are pretty good.

Basically avoid overly cheap amps,as the internals are often a bit cheap and nasty,but amps from Shanling,Mei-Xing,Consonance and a few others are all pretty decent bets.
 

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