SOLD WITHDRAWN DCB1 Preamp - Nelson Pass B1 Clone

[wHIZZY]

This is an extremely neutral and transparent sounding preamp which is built to a very high standard using - Modushop Galaxy case, Toroidy supreme transformer and I believe Audio note Tanalum resitors in the circuit board.

Direct coupled preamp (no coupling caps) based on Nelson Pass's B1 Buffer. It boasts symmetrical Salas shunt voltage regulators that use LED strings for very accurate voltage reference. Includes 5 relays for input signal switching and an output relay for delayed start-up muting. Being based on the B1 Buffer, Voltage Gain is close to 1 (buffer amp).

There is a very light mark on the top cover which shows up in certain lights.

Now also listed on eBay where you can find clearer higher resolution photos.

Selling on the WAM for it cost me - £425 collection preferred but will post at cost

 

[wHIZZY]

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[wHIZZY]

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[wHIZZY]

Eric Bump

 

[wHIZZY]

Bumpy

 

[Tony T]

Can you explain the difference between this and a typical active preamp? I have First Watt F5’ and may be interested, the F5 has 16db gain but I am unsure if this would be suitable fo me? Sorry for the questions

 

[wHIZZY]

Can you explain the difference between this and a typical active preamp? I have First Watt F5’ and may be interested, the F5 has 16db gain but I am unsure if this would be suitable fo me? Sorry for the questions.

I'm no expert but as I understand it the main design function of a buffer preamplifier such as the B1 is to minimise signal distortion caused by impedance mismatches between the source selected (CD, phono amp, tuner etc) and the power amp. It does this by acting as a buffer between high impedance input sources and the impedance of the power amp.

The other main difference is it further aims to minimise distortion by not adding signal gain, so eliminating any resulting distortion.. In other words it can reduce the input signal level but not increase them. As most signal sources outputs levels (CD, phono stages, tuner) are far to high to be fed directly into a power amp this is not normally an issue.

As you are already using a power amp designed by Nelson Pass I would imagine this pre also designed by him should match.providing you have fairly efficient speakers and don't need gain.

 Dave

 

[Tony T]

Ok, thank you for your help. I will have a think about it over the next few days.
Regardless, GLWTS
Tony

 

[montesquieu]

I'm a big fan of the DCB1 (I've owned several) - in general there is too much gain washing about in systems these days with the average CDP or DAC outputting something around 2.0 to 2.5 volts (most phono stages 1-2 volts) and a typical power amp around 26db on average

However, in this this context, the 16db is a bit low in overall gain terms .. the DCB1 has unity gain (0DB uplift) so the total gain in the system is going to be quite low. An active preamp with a modest amount of gain (6db-12db) would be a better option, I suggest, unless you have very high output from your sources or your speakers are particularly sensitive. (97db+).

Where the DCB1 really comes into its own is in systems where the sensitivity of the power amp is high and a passive pot or other gain-free device (eg a transformer volume control) would be used to avoid excessive gain - eg Leak Stereo 20, Radford STA25, or many solid state amplifiers designed to be used with a passive pot, into averagely-sensitives spealers. Where this is the case, its a superb, cost-effective option and far superior to a passive pot that would suffer from all sorts of impedance mismatch issues.

 

[ian917]

I have an almost identical DCB1 to this and I use it with an F6. You’ll need to spend a lot to get something better suited to your F5, unless you listen at very high levels.

 

[montesquieu]

I have an almost identical DCB1 to this and I use it with an F6. You’ll need to spend a lot to get something better suited to your F5, unless you listen at very high levels.

I'm not concerned about the quality which I'd be the first to say is very very high for the money involved. I'm concerned about the gain match, as I said 'unless you have very high output from your sources or your speakers are particularly sensitive'. What speakers are you using?

 

[ian917]

I'm not concerned about the quality which I'd be the first to say is very very high for the money involved. I'm concerned about the gain match, as I said 'unless you have very high output from your sources or your speakers are particularly sensitive'. What speakers are you using?

Q Acoustics Concept 300 - 84db/6ohm nominal impedance. Amp is 25w/8ohms and 50w/4ohms.

At normal listening levels I still have over 25% travel on the stepped attenuator available.

 

[Tony T]

I'm a big fan of the DCB1 (I've owned several) - in general there is too much gain washing about in systems these days with the average CDP or DAC outputting something around 2.0 to 2.5 volts (most phono stages 1-2 volts) and a typical power amp around 26db on average

However, in this this context, the 16db is a bit low in overall gain terms .. the DCB1 has unity gain (0DB uplift) so the total gain in the system is going to be quite low. An active preamp with a modest amount of gain (6db-12db) would be a better option, I suggest, unless you have very high output from your sources or your speakers are particularly sensitive. (97db+).

Where the DCB1 really comes into its own is in systems where the sensitivity of the power amp is high and a passive pot or other gain-free device (eg a transformer volume control) would be used to avoid excessive gain - eg Leak Stereo 20, Radford STA25, or many solid state amplifiers designed to be used with a passive pot, into averagely-sensitives spealers. Where this is the case, its a superb, cost-effective option and far superior to a passive pot that would suffer from all sorts of impedance mismatch issues.

Not sure if that’s aimed at me. I use Proac Tablette 10 signature with this particular setup, I do have Tannoy DMT12 II but they’re used in my main setup and besides it’s pretty clear that the F5’ runs out of steam pretty quickly when in combination with the Tannoy.
The use case will be late night listening in the near field with the Proac/F5 mono’s in a 6 metre long by 2.8 metre across conservatory with speakers firing across the width, listening position is around 4-6 feet from the speakers. Sources are Rega P8 & Rega Apollo with a Audiolab transpor, both via a Soncoz SGD1 DAC.

 

[montesquieu]

Not sure if that’s aimed at me. I use Proac Tablette 10 signature with this particular setup, I do have Tannoy DMT12 II but they’re used in my main setup and besides it’s pretty clear that the F5’ runs out of steam pretty quickly when in combination with the Tannoy.
The use case will be late night listening in the near field with the Proac/F5 mono’s in a 6 metre long by 2.8 metre across conservatory with speakers firing across the width, listening position is around 4-6 feet from the speakers. Sources are Rega P8 & Rega Apollo with a Audiolab transpor, both via a Soncoz SGD1 DAC.

Soncoz is a whacking 4V output so you have lots available there if you need it. No surprise though the amp is not working with Tannoys I tried both F5 and F6 with mine (12in HPD-based) and while pleasant enough, neither really lit them up properly even at 91db sensitivity (and an active preamp). The Proacs are only 86db so I would definitely be careful using a unity gain pre even if using late at night/near field.

 

[Tony T]

Soncoz is a whacking 4V output so you have lots available there if you need it. No surprise though the amp is not working with Tannoys I tried both F5 and F6 with mine (12in HPD-based) and while pleasant enough, neither really lit them up properly even at 91db sensitivity (and an active preamp). The Proacs are only 86db so I would definitely be careful using a unity gain pre even if using late at night/near field.

Unfortunately I’m in agreement with you, a little bit of reading confirms that the DCB1 is not tailored to my needs.
OP, sorry for barging in on your sales thread. GLWTS

 

[wHIZZY]

Unfortunately I’m in agreement with you, a little bit of reading confirms that the DCB1 is not tailored to my needs.
OP, sorry for barging in on your sales thread. GLWTS

Not a problem, I'm in total agreement that if you are concerned there is not enough gain then it would be foolish to purchase the amp and I'm not over concerned if it doesn't sell, it's more about making space and it being appreciated and used than raising money.

 

[wHIZZY]

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