DAC direct to Spectral Amps

marty

Well-Known Member
Apr 20, 2010
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It's been said a number of times - Spectral amps are current driven, and very few DACs or other preamps can properly drive them. Spectral eased the language in some recent amps, like the 400RS, but tightened it again in the 300RS. That alone creates user confusion, and understandably so. Other functions provided by their preamps include DC and oscillation protection, and I have triggered the DC-offset protection circuit a number of times with my Pass XP-25 myself; apparently, it is not all that stable in that department.

Tasos is correct but there's more. Spectral has flip-flopped on this issue more than Mitt Romney. Although my 400 owners manual specifically says the only requirement is to use a low output impedance pre-amp, they have now instructed their dealers not to sell a Spectral amp of any kind to someone not using a Spectral pre-amp. This is at least the 3rd or 4th flip- flop in over 20 years. Wow. It's more confusing than "fat Oprah?" thin Oprah?" Make up your mind already Spectral and stick to it!
 

Console

Member
Apr 17, 2017
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Timbuktu ;)
So... Since 3 days I have a DMC 30 SL G2 in my system. Compared to DAC direct, there is a huge difference in Sound!
The 30 SL goes into 180 via Shotgun S1, and along with this I bought a MH 770 UL. All stuff was from a collector and still boxed new and 100% mint. This Pre changed worlds compared to Weiss DAC 202 direct: Timbre, Imaging, soundstage, dynamics and flow changed a few level. So: DAC direct works, but after having the Pre in since someone days, I would not recommend it at all!
 

lydon

New Member
Jul 10, 2011
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Marty, I was thinking about what would Spectral's position be if the company were to ever get around to developing their own SOTA DAC. You know, that every safe guard would be exercised so the amps wouldn't burn up because the design could/would support driving those amps without a pre amp in the singal path. But today, according to Spectral, there's something which is beyond our collective understanding that would jeopardize the warranty should we want to drive those beautiful amps directly with our DAC's which is just ludicrous.
 
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ack

VIP/Donor & WBF Founding Member
May 6, 2010
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Marty, I was thinking about what would Spectral's position be if the company were to ever get around to developing their own SOTA DAC.

If the 4000SV is any indication, its really low output makes it sound very thin driving the amps; so, I guess QED, no need to guess what the DAC might do. I measured -12dB difference between my Alpha and the 4000SV.
 

BMCG

VIP/Donor
Oct 1, 2016
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If the 4000SV is any indication, its really low output makes it sound very thin driving the amps; so, I guess QED, no need to guess what the DAC might do. I measured -12dB difference between my Alpha and the 4000SV.

Indeed...and at the risk of (re)stating Spectral's design philosophy....their intent is clearly to offer products that work best together.

if you dislike this approach...don't select Spectral..not like there's a lack of alternates.
 

ack

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May 6, 2010
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Moreover, there is no volume control in the player, nor was there one in the previous DAC, so probably unlikely there will be one in the new DAC
 

lydon

New Member
Jul 10, 2011
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But that would mean that the DAC would not be SOTA. Just for a moment, imagine, that the consumer of this device is a single source person, just digital. The analog outputs are the same quality as those found on the latest Spectral pre amp. The lastest SHHA modules, the fabulous volume control pot, etc. etc. Then why would you need to take that extra step of requiring the use of a pre amp? That my friends is already happening today without the blessing of the company, but with some risk. It's called pushing the envelope. Now should Spectral create such a DAC then I would fully expect the company policy to be they don't require a pre amp and your warranty would be honored to safeguard your investment in an amplification system. Now that would be truly SOTA engineering as well as thinking on their part. Wouldn't you agree?
 
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ack

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May 6, 2010
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You may be making too many assumptions regarding an analog volume control inside the DAC or player - an analog volume control (which is what they apparently favor) usually sits between an active buffer and an output stage (for a number of reasons, one being to keep input and output impedances fixed), and if the player has only an output stage, you are asking for a lot more complexity than you think. Obviously, I don't have their schematics, but it seems to me the player does indeed have just an output section. In other words, you are suggesting to effectively put the basics of an analog preamp inside the player or DAC, and that means a lot more than just an additional potentiometer. Since you are then implementing the basic circuitry of a preamp you might as well offer additional analog inputs. Well, FWIW, such a thing existed in the SDR-1000 from the 80's. By now, I am sure you are thinking, well, so many other DACs have variable output - true, like mine, but how many of them sport true analog volume controls.

Moreover, to say that the DAC would not be SOTA for lack of variable output is like saying no phono preamp w/o one can be SOTA either; or any other source, like a Sequerra tuner, or a tape deck.

You do have good points, but I feel they are overly simplistic. There was also a thread here a while ago on this very issue: why not put a preamp inside the DAC with additional inputs... I was too lazy to respond.
 
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lydon

New Member
Jul 10, 2011
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Yeah, I'm no electronics engineer thats for sure. Though my material point is that; in this 40th year of the Spectral brand I personally would love to see the team create a truly great SOTA DAC that all user would be proud own and use daily. The company's white board in the past has surely changed throughout the years with other companies designs capturing the attention of those at Spectral. But should they market their own unique design let it not be a standard affair. It could simply come down to whether or not the company wants the investment in a (pre amp & amplifier) and then you can do as you will. Which exist today and that would just be a profound disappointment. For as long as enthusiasts have been waiting for a phone stage from Spectral whatever makes it way to market, my hope is that their future DAC will be spectacular in every way that matters to those who listen and take there listening seriously. Being able to bypass the pre amp would be in my opinion one such indication of the technical advancements to make it truly SOTA.
 
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rjc1845

Well-Known Member
Jun 22, 2016
37
5
113
Greater Boston
Well, I started this thread back in April to explore an entry to Spectral electronics. As you all know, it requires a commitment to both Spectral/MIT which is difficult for many. My path has been circuitous and at moments I was ready to abandon the idea. Since April, I first upgraded my Pass INT60 to a Pass 350.8.......second step was to move to Magico S3 from S1. I ran my DAC volume control (Bricasti M1SE) direct to the 350.8. I tried fine tuning the system with a variety of signal and power cables with varying degrees of success but still continued to find holes in the sound.
I then decided to eat the elephant one bite at a time by acquiring the MIT cables. I bought a Matrix 50 Proline and then HD60 speaker cable. These cables performed as advertised...wonderful bass, spacious soundstage but I felt lacked PRAT and at times seemed they were missing something tonally ( particularly violin and upper piano frequencies). Bear in mind, Bricasti to Pass amp.
Well, in the last few days, I finally found HD 90.1 and a DMC30 SS Series 2 (late s/n 309 + ....thank you ACK) and the system change has been transformational to my ears. PRAT is there in spades, instruments sound real, low level detail retreival is exceptional and dynamics superb.
Now the dichotomy, will DMA360 S2 be an improvement......time will tell.
 

ack

VIP/Donor & WBF Founding Member
May 6, 2010
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Well done! We should meet
 

PeterA

Well-Known Member
Dec 7, 2011
10,156
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North Shore of Boston
Yeah, I'm no electronics engineer thats for sure. Though my material point is that; in this 40th year of the Spectral brand I personally would love to see the team create a truly great SOTA DAC that all user would be proud own and use daily. The company's white board in the past has surely changed throughout the years with other companies designs capturing the attention of those at Spectral. But should they market their own unique design let it not be a standard affair. It could simply come down to whether or not the company wants the investment in a (pre amp & amplifier) and then you can do as you will. Which exist today and that would just be a profound disappointment. For as long as enthusiasts have been waiting for a phone stage from Spectral whatever makes it way to market, my hope is that their future DAC will be spectacular in every way that matters to those who listen and take there listening seriously. Being able to bypass the pre amp would be in my opinion one such indication of the technical advancements to make it truly SOTA.

How would one be able to use the long awaited Spectral phono and Spectral DAC without a pre amp? Are you suggesting that both pieces should have variable outputs?
 

Mdp632

Well-Known Member
May 30, 2016
416
124
148
Well, I started this thread back in April to explore an entry to Spectral electronics. As you all know, it requires a commitment to both Spectral/MIT which is difficult for many. My path has been circuitous and at moments I was ready to abandon the idea. Since April, I first upgraded my Pass INT60 to a Pass 350.8.......second step was to move to Magico S3 from S1. I ran my DAC volume control (Bricasti M1SE) direct to the 350.8. I tried fine tuning the system with a variety of signal and power cables with varying degrees of success but still continued to find holes in the sound.
I then decided to eat the elephant one bite at a time by acquiring the MIT cables. I bought a Matrix 50 Proline and then HD60 speaker cable. These cables performed as advertised...wonderful bass, spacious soundstage but I felt lacked PRAT and at times seemed they were missing something tonally ( particularly violin and upper piano frequencies). Bear in mind, Bricasti to Pass amp.
Well, in the last few days, I finally found HD 90.1 and a DMC30 SS Series 2 (late s/n 309 + ....thank you ACK) and the system change has been transformational to my ears. PRAT is there in spades, instruments sound real, low level detail retreival is exceptional and dynamics superb.
Now the dichotomy, will DMA360 S2 be an improvement......time will tell.

Thanks for sharing. I'm also considering the move from Pass electronics to Spectral. But, I'm still doing some research and listening.

With regards to your source. How are you feeding that Bricasti DAC? E.g. A laptop or a dedicated server?

Do you have any other sources in your system?
 

rjc1845

Well-Known Member
Jun 22, 2016
37
5
113
Greater Boston
I only use digital for source material. Feeding the Bricasti with Sonore microRendu with their Signature power supply with SR fuses and Cardas power cord/ Roon- NAS-Tidal.
 

rjc1845

Well-Known Member
Jun 22, 2016
37
5
113
Greater Boston
a brief update to my above post regarding the 30Ss-2 I'll lieu of DAC direct. Today, I have the Spectral 300 in for demo to compare to the Pass 350.8. The good folks at my local shop have been extremely accommodating and I now recognize the value add they can deliver. I have the next 4 days to sort things out but from an erfonomic standpoint , I much prefer 70 pounds that fits in lower shelf of my GPA rack vs. the big Pass.
 

Mdp632

Well-Known Member
May 30, 2016
416
124
148
a brief update to my above post regarding the 30Ss-2 I'll lieu of DAC direct. Today, I have the Spectral 300 in for demo to compare to the Pass 350.8. The good folks at my local shop have been extremely accommodating and I now recognize the value add they can deliver. I have the next 4 days to sort things out but from an erfonomic standpoint , I much prefer 70 pounds that fits in lower shelf of my GPA rack vs. the big Pass.

I'm looking forward to your impressions and comparisons. I assume you are using a balanced connection between the pre and amp ?
 

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