Preamps for the 120.....

I've tried various combinations and currently settled for the following:

Pass B1 buffer in front of my VTA ST70 in one system
SP14 in front of a Pass F5 Turbo in the other system

I also tried a passive selector / attenuator, which sounded lifeless with either amp.

Kind regards

Michael

I was just about to pull the trigger on an SPxx but last minute decided I might be looking at one of the McIntosh tube pre-amps instead. Maybe rebuild an old C22 or C20.....that's the plan for the next 2 hours anyway! I'm actually in the market for a new Pre-amp, not sure which way to go. If I had the dough I'd get a used C2200 or 2300 and be done with it.

cci1492 wrote:I was just about to pull the trigger on an SPxx but last minute decided I might be looking at one of the McIntosh tube pre-amps instead. Maybe rebuild an old C22 or C20.....  

Just had a look at some of the prices on the C22....Holy moly!!

I think once i am totally finished with the last odds and ends on my amp I will look at an SPXX...not sure which one tho

mcgyver74 wrote:

cci1492 wrote:I was just about to pull the trigger on an SPxx but last minute decided I might be looking at one of the McIntosh tube pre-amps instead. Maybe rebuild an old C22 or C20.....  

Just had a look at some of the prices on the C22....Holy moly!!

I think once i am totally finished with the last odds and ends on my amp I will look at an SPXX...not sure which one tho

The Mac would be a fun project but probably void the warranty

I have both the SP-13 and SP-14, with mods by Don Sachs. You cannot go wrong with either one.

Should you experiment with the 6SN7-based SP-14 you *will*, at some point, want to experiment with some top-grade Chinese CV-181 tubes in the 6SN7 holes, which tubes are too tall for the standard SP-14 case with the lid on. Maybe Roy has a fix for this. My Sachs SP-14 leaves the tubes exposed above a combination wood and metal chassis so height is not a problem.
There is an ample array of 6CG7 (SP-13) and 6SN7 (SP-14) tubes out there, and whichever pre-amp you go to, the sound differences are infinitesimal provided care in component, esp. tube and cap selection. Neither will disappoint and I think A-B'd against a Mac of any vintage you're in for a pleasant surprise.

mcgyver74 wrote:

cci1492 wrote:I was just about to pull the trigger on an SPxx but last minute decided I might be looking at one of the McIntosh tube pre-amps instead. Maybe rebuild an old C22 or C20.....  

Just had a look at some of the prices on the C22....Holy moly!!

I think once i am totally finished with the last odds and ends on my amp I will look at an SPXX...not sure which one tho

You can also look at the McIntosh MX110Z. I love the sound of mine with my M125 monoblocks. If you're patient, you can find one for around $1k.

Somewhere back a few pages on this forum is my review description of my SP14 pre amp (playing with my vta st-70. Despite the passage of a few years, it is still true love. This was an upgrade from another of Roy's pre amps... SP 8 or 10... I forget. It was a big improvement, not that I had any complaints about the old one. I still have it. Loved it. My son's getting it next. But the SP 14! I think Bob probably isn't exaggerating back on page 1 of this thread.

Tube Nube wrote:Somewhere back a few pages on this forum is my review description of my SP14 pre amp (playing with my vta st-70. Despite the passage of a few years, it is still true love. This was an upgrade from another of Roy's pre amps... SP 8 or 10... I forget.  It was a big improvement, not that I had any complaints about the old one. I still have it. Loved it. My son's getting it next. But the SP 14! I think Bob probably isn't exaggerating back on page 1 of this thread.

How much heat does the 14 throw? I need a pre-amp that will sit in a drawer and I don't want it to overheat or burn up my cabinets

mcgyver74 wrote:


How much heat does the 14 throw?   I need a pre-amp that will sit in a drawer and I don't want it to overheat or burn up my cabinets

Got a pic of this cabinet? Can air flow through the space you want to put this in?

I have used three preamps with my VTA ST120. The first is actually a Xiang Sheng DAC01A that I have configured to be able to use the volume control for the RCA outputs and which can serve as a source selector and thefefore, as a standalone preamp. From this I can run the DAC01A outputs to either an old SS Hafler DH101 with phono amp, tone and balance controls or to a Transcendent Sound Grounded Grid tube preamp. All three configurations work well and I can't really tell much of a difference among them. It just depends on how I am feeling on any given day that determines what I will use.

corndog71 wrote:

Got a pic of this cabinet?  Can air flow through the space you want to put this in?

Kind of, it has a glass front that is a drawer, and there is a shelf inside the drawer,  the back is partially covered but air can get out...

Crappy photos here

https://s1024.photobucket.com/user/mhering74/library/Misc

mcgyver74 wrote:

corndog71 wrote:

Got a pic of this cabinet?  Can air flow through the space you want to put this in?

Kind of, it has a glass front that is a drawer, and there is a shelf inside the drawer,  the back is partially covered but air can get out...

Crappy photos here

https://s1024.photobucket.com/user/mhering74/library/Misc

It's not ideal. If I were you I would be looking at other cabinets. Something that air can actually flow through. Are you thinking the preamp would replace that receiver? Is that a PS4 in there too? Putting that in a closed cabinet will probably shorten its life. It is a computer after all and they do not like hot environments. It looks like you could fit a preamp to the right of the amp on top. You just have to move whatever is over there.

That is an old PS3 that I am likely dumping since I don't use it anymore and yes the plan would be to replace the receiver with the preamp.

Sadly replacing the cabinet is not in the cards, my XYL is very understanding about my hobbies but there are limits

overall, shouldn't run any hotter than a 100w light bulb (the old fashioned incandescent type, not a new florescent or LED bulb)

Thanks  100 Watt bulb would quickly roast the inside of that cabinet

I was really hoping I could build an SP14, but looks like I may need to go SS for the pre

mcgyver74 wrote:That is an old PS3 that I am likely dumping since I don't use it anymore and yes the plan would be to replace the receiver with the preamp.

Sadly replacing the cabinet is not in the cards,  my XYL is very understanding about my hobbies but there are limits

Just tell her that they get hot and need airflow. If you have to put it in the cabinet and it breaks then it's her fault.

mcgyver74 wrote:Thanks  100 Watt bulb would quickly roast the inside of that cabinet

I was really hoping I could build an SP14, but looks like I may need to go SS for the pre

You mentioned that the cabinet is open in back? Install one (or several) cooling fans powered from a 12VDC, 1A wall-wart.

https://www.amazon.com/Cooler-Master-Bearing-Computer-Radiators/dp/B000O8I474  

That will allow you to do pretty much whatever you want.

Trash the drawer and convert to an open shelf? Maybe line the inside with rubber or cork matting, or cover it with a carpet scrap ...

Another option might be to drill a bunch of holes in the top of the drawer area and the drawer itself so heat can rise and dissipate.

sKiZo wrote:Trash the drawer and convert to an open shelf? Maybe line the inside with rubber or cork matting, or cover it with a carpet scrap ...

Adding an insulator??

Really??

Unfortunately modding the cabinet is out of the question, the XYL loves that piece.

She is so great with all my hobbies that I have to be supportive when she asks something.

I can open the front and look at a fan, but it's near the wall and I worry the heat will hurt that paint

"We are anticipating the ST-1 to begin shipping later this year." I'm willing to wait for this unless a great Mac deal becomes available.

mcgyver74 wrote:Unfortunately modding the cabinet is out of the question,  the XYL loves that piece.

She is so great with all my hobbies that I have to be supportive when she asks something.

I can open the front and look at a fan, but it's near the wall and I worry the heat will hurt that paint

Good paint will not be disturbed by that level of heat.

Now, how would she feel about a re-paint and accent wall? You get many points at a low cost and can upgrade the paint as needed.

Sadly we just finished re-painting the entire apartment, She's not likely to change colors

I just wonder how hot that pre would get temp wise, I mean my 120 throws some pretty good heat (Those outputs can get upwards of 250 degrees and the rectifier can get up to 300) that would bake the cabinet good and likely cause failure

mcgyver74 wrote:Sadly we just finished re-painting the entire apartment,  She's not likely to change colors

I just wonder how hot that pre would get temp wise,  I mean my 120 throws some pretty good heat (Those outputs can get upwards of 250 degrees and the rectifier can get up to 300) that would bake the cabinet good and likely cause failure

The OEM Dynaco PAS3 has a total of five tubes in an unvented chassis.  4 x 12AX7, 1 x 12X4. It barely gets warm to the touch. Mine lives on a shelf with an FM3 above it and an AF6 below it.

Once upon I time, I had a Scott LC21, which apart from being entirely unremarkable, also did not throw any heat worth worrying about.

Small signal tubes of the 6XXX or 12XXX varieties don't make much heat.

Would the SP14 have similar heat output to the PAS3?

mcgyver74 wrote:Would the SP14 have similar heat output to the PAS3?

No, it would not. The SP14 is configured around five (5) octal tubes that, by their very nature make more heat than miniature tubes. That would be a Roy/Bob question as to whether you might be able to configure a fan on the 14 to move enough air to make up the difference. Keep in mind that the 6SN7 is NOT a KT88/6550 or any other power-pentode, such that the heat from it is a fraction of what the output tubes deliver. But, still more than a PAS.

Which, as it happens, would not be all that bad an option *and* give you a phono pre-amp. Lots-O-aftermarket upgrades as well.