Don Sachs SP14 Tube Preamp Review

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JackD

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #260 on: 18 Nov 2017, 01:57 am »
Ashgar

There is supposed to be another new firmware upgrade coming in the next couple of weeks according to Paul.  Ted Smith has made even more improvements.

A_shah

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #261 on: 18 Nov 2017, 03:22 am »
Ashgar

There is supposed to be another new firmware upgrade coming in the next couple of weeks according to Paul.  Ted Smith has made even more improvements.

Jack ,
Did not know , will ask  Jeremy Bretey at PS audio next week and check on that ! they have excellent customer Service ! Yes I seen the Video's of TED explaining his FPGA technology in detail , I also read Jim Austins Review of Benchmark DAC 3 HGC comparing it to the Directstream  :duh: maybe with his ears and his  review hat should have compared it to the GTE Trinity  DAC , something I can't afford I would have believed him , needless to say I have heard the Benchmark DAC, sure it's good just sounds  different www.tnt-audio.com/sorgenti/trinity_tech_e.html

JackD

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #262 on: 18 Nov 2017, 03:38 am »
Jim is more than a little off the rails with that review. The different chip groups definately do not sound the same.  The new firmware will be called Redcloud.  Now that you have the DS you ought to join the PS forum. 

A_shah

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #263 on: 18 Nov 2017, 03:46 am »
Jim is more than a little off the rails with that review. The different chip groups definately do not sound the same.  The new firmware will be called Redcloud.  Now that you have the DS you ought to join the PS forum.


Jack
Thank you !  will do !    :thumb:

tdinut

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #264 on: 28 Nov 2017, 10:38 pm »
Hi Don,

I could not seem to find the actual number, but can you please tell me what the lowest output impedance you can achieve with your line stage?

I have several amps but I think the lowest Input Impedance on my amps is one with an Input Impedance of 10,000 ohms.

So I am curious what you'd be able to achieve via the output impedance on the preamp.

Thank you!


mresseguie

Re: Don Sachs SP14 Tube Preamp Review
« Reply #265 on: 29 Nov 2017, 01:23 am »
Hi Don,

I could not seem to find the actual number, but can you please tell me what the lowest output impedance you can achieve with your line stage?

I have several amps but I think the lowest Input Impedance on my amps is one with an Input Impedance of 10,000 ohms.

So I am curious what you'd be able to achieve via the output impedance on the preamp.

Thank you!

Hello, Joe.

I believe my Model 2 has Jupiter Cu 2.2 uF caps inside because my SS amp has an input impedence of 10k ohms.

I've had the Model 2 for a year now and I love it.

Michael

tdinut

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #266 on: 29 Nov 2017, 01:26 am »
Thank you very much Michael.

I've been trying to catch up on this thread. Looks like a lot of Don Sachs love here. This is extremely encouraging. I appreciate your response. I should talk to Don about an order and options.



dls123

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #267 on: 29 Nov 2017, 01:37 am »
Hello, Joe.

I believe my Model 2 has Jupiter Cu 2.2 uF caps inside because my SS amp has an input impedence of 10k ohms.

I've had the Model 2 for a year now and I love it.

Michael


I usually use a .47 uF cap which will get you down to 70K or so input impedance.   If you have a 10K SS amp then you need 2 uF output caps.  That will do the trick nicely.  About $50-60 extra cost, that's all

Don

tdinut

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #268 on: 29 Nov 2017, 01:39 am »

Hi Don,

Thank you for taking the time out to answer my question.

I'll call to discuss additional options and upgrades.




I usually use a .47 uF cap which will get you down to 70K or so input impedance.   If you have a 10K SS amp then you need 2 uF output caps.  That will do the trick nicely.  About $50-60 extra cost, that's all

Don

Speed Racer

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #269 on: 29 Nov 2017, 02:19 am »
Deleted (Apparently nonsensical information)
« Last Edit: 29 Nov 2017, 07:07 am by Speed Racer »

A_shah

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #270 on: 29 Nov 2017, 02:30 am »
I have two sets of caps in my DS-2 one set is Jupiter's  i believe 1.uf that go goes down to 47K and the second set is is 3.0uf  Audiocap theta film caps & foil caps bypassed by Russian Teflon caps which according to Don brings it down to 2.3Hz technically flat down to 20HZ( their is no music below 30 Hz any way )
So for as  impedance  mismatch is concerned  ? I have had no issues with my Odyssey Kismet amplifier or my 3 DAC's that i tested the unit with  PS audio Directstream DAC,  Chord Mojo, or the Schiit Gungnir )
The 3.1 audio theta  combo caps has allowed me to disconnect my Hsu VTF-15 Mk11 Subwoofer from my two channel system , I get more than enough Bass with the DS-2 & Directstream Combo

Speed Racer

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #271 on: 29 Nov 2017, 03:01 am »
Mine will have two sets of caps as well. For my Pioneer M-22 at 50,000 Ohms we will use 2.0uF Audiocap Theta caps bypassed by Russian teflon caps on one output. For the tube amp I may someday buy, another output will have .47uF Multicap RTX caps bypassed by Russian teflon caps.

That's is what Don said would sound the best so that is what I am going with!!

dls123

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #272 on: 29 Nov 2017, 03:26 am »
10K ohms SS amp? Wouldn't you need 8 uF for that if you want the roll off to be good at 20 Hz?

I used this calculator:

https://www.v-cap.com/coupling-capacitor-calculator.php

...and assumed that the -3 dB point would be 2 Hz for a rolloff below 20 Hz. Using 2 uF caps means the roll off is good until 80 Hz.

HI
That cap calculator is nonsense.  They want you to assume that the LF rolloff will start at 10X the value of the -3 dB point. They want to sell you a large and expensive cap.  The reality of it is that 3 octaves is plenty and 2 octaves is really sufficient.  An octave is 2X the frequency value.  So even 3 octaves is only 8X.   If you keep the - 3 dB point below 5 Hz I seriously doubt you will hear any LF loss into your amp.  If you really want to drive a 10K load then you can go 3 uF.  Into 10K to get a 5 Hz -3dB point you need 3.185 uF of capacitance.   So 3 uF is fine.  The thing is, that besides cost, there is a tradeoff in sonic quality between values as you get a larger cap value.  More phase error, etc...  I cannot hear any difference in cap sizes up to about 3 uF.  If I put a 4.7 uF cap in I don't think it sounds quite as good.  So you are using a larger cap to avoid any rolloff at all below 20 Hz and giving up sound quality.  The reality is that there is little if any music below 25-30 Hz unless you are into electronica or Bach organ fugues.  Piano goes down to 27.5 Hz and bass about 30 Hz.  Also, most people don't have speakers that will play below 30-35Hz.   So if you use a 3 uF cap you might get a smidge of LF rolloff into 10K between 20 and 35 Hz, but your speakers and the music itself don't go down there anyway.  So you put a 4.7 uF cap in the preamp to get performance you don't need and it doesn't sound quite as good as the 2 or 3 uF cap.   

Quite frankly I never understood why on Earth a manufacturer would make ANY amp with a 10K input impedance.  There are plenty of good SS amps out there with 47K input impedance and some are 100K.  It has nothing to do with SS vs. tube.  Any tube amp I have ever seen is 80K or higher and most are 100K.   My KT88 amp is 220K.   If I am building an amp and matching preamp for a customer I use .33 uF caps.  That gives a -3 dB point of 2.2 Hz and a nice small output cap.   

mresseguie

Re: Don Sachs SP14 Tube Preamp Review
« Reply #273 on: 29 Nov 2017, 03:57 am »
Hello, Speedy.

I see Don's already answered your question.  :)

My specific situation with my preamp was that I have a pair of two-way monitors that play down to 43Hz. When I commissioned Don to make my preamp, I told him I wanted to be able to power a pair of subs, so one pair of outs has caps for subs and my Jupiter Cu caps are for the two-ways. I haven't bought the subs yet, but once I do, the monitors will only play down to ~100Hz or 110Hz.

When you get your preamp and allow for some burn in, come back here and tell us what you think of it. I suspect you'll be pleased.

Michael


JackD

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #274 on: 29 Nov 2017, 05:36 am »
Michael

Don't you now own a pair of full range speakers that go down into the 20's?. How will that cap choice in partnership with Don's amp react to those speakers?

mresseguie

Re: Don Sachs SP14 Tube Preamp Review
« Reply #275 on: 29 Nov 2017, 05:57 am »
Hi, Jack.

You are correct. I do own a pair of Daedalus Apollos. They're definitely full range. Not only did they not exist when I ordered my Model 2, I hadn't planned on making such a purchase. I guess I could say that after listening to them for about three hours, I just couldn't imagine not buying them. [This is the same exact thing that I experienced while sitting in Don's living room listening to his audio system. I knew I'd be a fool to say, "Thanks for your time, but I'll just have to think about it for a while." Of course I told him I'd buy his preamp. :banana piano:] For now, the Apollos and my Kootenay 120 will remain in WA/OR. I will either buy a second Model 2 from Don (!) or a DAC/pre to power the amp.

Okay. I should say a 2nd Model 2 is a possibility. A DAC/pre is a possibility. A totally different preamp is a possibility. I have some time to make my decision. In the mean time, I will use my Nuprime DAC-9 for my preamp needs. Once I do make a decision and purchase the item(s), the DAC-9 will be used in an office system.

« Last Edit: 29 Nov 2017, 07:23 am by mresseguie »

Speed Racer

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #276 on: 29 Nov 2017, 06:10 am »
Jeez, I am sorry I responded.....

mresseguie

Re: Don Sachs SP14 Tube Preamp Review
« Reply #277 on: 29 Nov 2017, 07:26 am »
Speedy,

It's all good. This is a part of our education. We make assumptions and ask questions. Then, we get really good answers from folks who really know their stuff.

There are no stupid questions. We're all learning this stuff. :thumb:

tdinut

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #278 on: 29 Nov 2017, 10:21 am »



+1


 :beer:



Speedy,

It's all good. This is a part of our education. We make assumptions and ask questions. Then, we get really good answers from folks who really know their stuff.

There are no stupid questions. We're all learning this stuff. :thumb:

dls123

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Re: Don Sachs SP14 Tube Preamp Review
« Reply #279 on: 30 Nov 2017, 03:56 am »
Michael

Don't you now own a pair of full range speakers that go down into the 20's?. How will that cap choice in partnership with Don's amp react to those speakers?

Hi
My amp has a 220K input impedance.  That means that even a .33 uF output cap in the preamp driving it will easily be flat down the 20 Hz into it.  The base preamp price and build is a .47 uF cap, which will easily drive any tube amp there is and be flat down to 20 Hz.