Who is using a preamp with their ST70?

[JayJH]

I am trying to decide if I really need additional gain from a preamp. I recently built the DIYTube driver board and I have it hooked up the line out of my sound card. I will soon get a tube USB DAC, probably the Scott-Nixon USBTD. I am not sure what the output of that DAC is.

Does it look like there would be a benefit to a preamp in my system. If so, are there any suggestions?

[Slartibartfast]

I am trying to decide if I really need additional gain from a preamp. I recently built the DIYTube driver board and I have it hooked up the line out of my sound card. I will soon get a tube USB DAC, probably the Scott-Nixon USBTD. I am not sure what the output of that DAC is.

Does it look like there would be a benefit to a preamp in my system. If so, are there any suggestions?

I have a modded Dynaco PAS as my preamp connected to my ST-70. I need it for my turntable and CD player. The CD player has no volume control and the near 2.0v output drives the ST-70 to levels that are too loud.

Also an iPod's output level is too low for my liking to drive the amp.

I do not have my computer hooked up to any of my tube equipment, so I can not speak to that.

Robert

[kheper]

I am trying to decide if I really need additional gain from a preamp. I recently built the DIYTube driver board and I have it hooked up the line out of my sound card. I will soon get a tube USB DAC, probably the Scott-Nixon USBTD. I am not sure what the output of that DAC is.

Does it look like there would be a benefit to a preamp in my system. If so, are there any suggestions?

To me going direct into the amp from a DAC with a pot on the amp, which controls the volume, the resulting sound is a bit too thin.

When I use the software control on an app, which controls the volume, directly into an amp which lacks a pot, the sound is lifeless.

With a pre-amp, there is greater stereo separation, than without. Adcom pre-amps have a 'contour' control which boots the bass and treble, proportionally defeating as a the volume is raised. This is very helpful at low listening levels.

[K-MAN]

I use a preamp with my computers DAC and I feel it adds some warmth to the music, plus it's nice to have the treble and bass controls when listening to vinyl.

[sprucemoose]

i am also using a PAS preamp to feed my st70. i need it for the phono stage and switching (2 phonos), and to control the volume of my sony D-5 cd player. and i do like to have the option of loudness and tone controls.

[JayJH]

So it looks like it would be a good idea to use one.

Anyone have any luck with one of the Aikido boards?

[burnedfingers]

Quote
Anyone have any luck with one of the Aikido boards?

I've built a number of them. I have some Aikido's that are hand wired as well as some that I have put together using the boards that diyaudio had in a group buy as well as the boards John Broskie sells.

I've built several using 6SN7 / 6sn7. point to point. A 6AU6 / 5687 point to point. I've built several dual mono 6FQ7 / 5687's and 6N1P / 5687.

They are very uncolored and neutral in my opinion and well worth building. I've put them up to preamps costing 2K and they have come out the winner.

[TerrySmith]

I still use my copy of sorenj07's 6SN7 linestage. You can find it buried in this forum somewhere. Very easy to build!

I did do a couple of tweaks as it had too much gain, remove the cathode caps, and added some feedback.

Found the thread: http://diytube.com/phpBB2/viewtopic.php ... =linestage

[JayJH]

Quote
Anyone have any luck with one of the Aikido boards?

I've built a number of them. I have some Aikido's that are hand wired as well as some that I have put together using the boards that diyaudio had in a group buy as well as the boards John Broskie sells.

I've built several using 6SN7 / 6sn7. point to point. A 6AU6 / 5687 point to point. I've built several dual mono 6FQ7 / 5687's and 6N1P / 5687.

They are very uncolored and neutral in my opinion and well worth building. I've put them up to preamps costing 2K and they have come out the winner.

Can you recommend one of the Aikido boards or tube combos over the others? The tubecad site doesnt really discuss the differences between the boards.

[rockable]

I'm using a NAD 1700 preamp that works well for my ST-70. I know there are a bunch of Adcom fans out here, too. I'm mostly using the system with CD's and ipod at this time.

[JayJH]

As my amp breaks in the sound seems to be getting thinner and more treble biased. Probably more articulate but more fatiguing because of the treble. It hasnt lost its bass, just more treble now.

Is this normal and will a preamp make it fuller and a flatter frequency response?

[kheper]

As my amp breaks in the sound seems to be getting thinner and more treble biased. Probably more articulate but more fatiguing because of the treble. It hasnt lost its bass, just more treble now.

Is this normal and will a preamp make it fuller and a flatter frequency response?

I have never experienced more treble as a function of age. As the caps break in, my amps seem less harsh to the ear. You may want to roll some different driver tubes or change some caps.

A good preamp should not add any coloration to the sound. It should only provide volume control. The frequency response should be the same. Some use the tone controls to compensate for what the amp does not have.

[burnedfingers]

Quote
Can you recommend one of the Aikido boards or tube combos over the others? The tubecad site doesnt really discuss the differences between the boards.

My personal favorite is the 6FQ7/5687 combo. You can change the 6FQ7 and roll others like a 6N1P, 6922, 6DJ8 just to mention a few.

Second choice would be the 6SN7/6SN7 really smooth and laid back just a hair.

The 6AU6/5687 has way too much gain but sounds good. The draw back is that the 6Au6 tubes must be selected for low noise.

[GrooveGrinder]

Consider the buffering function of a preamp.
You may not need gain, but you may need
buffering..

Consider also, transformer based volume controls.
There are several out there, but I haven't seen
any cheap.

You might build a simple tube buffer stage, with
a volume control, and put it in a box.

Buffering can ameliorate sound quality issues
caused by various mismatches and other thing.

[JayJH]

I just ordered the 6sn7 Aikido kit last night. Ill need to figure out a power supply. From what I have heard about this I have high hopes for it.