a passive buffer bass performance?
Gents, I also have interest in the subject of passive buffer versus active preamp especially in a bass application.
I am looking at putting a preamp after a miniDSP, to drive a long cable (5-6m) around the room to a mono Dclass amp which drives the sub. The mono amp takes a balanced input and has plenty of Vgain (30-31dB), so technically a passive preamp should be better not to saturate the amp input.
However I will try an alephP here first since I am already putting two of those together, but I might consider later selling one and doing a DC-coupled, balanced passive with a unity gain instead.
Would a B1 (Mezmerize) be a good fit for the job or something else?
Gents, I also have interest in the subject of passive buffer versus active preamp especially in a bass application.
I am looking at putting a preamp after a miniDSP, to drive a long cable (5-6m) around the room to a mono Dclass amp which drives the sub. The mono amp takes a balanced input and has plenty of Vgain (30-31dB), so technically a passive preamp should be better not to saturate the amp input.
However I will try an alephP here first since I am already putting two of those together, but I might consider later selling one and doing a DC-coupled, balanced passive with a unity gain instead.
Would a B1 (Mezmerize) be a good fit for the job or something else?
dB ratios should be like second nature to Audio enthusiasts and especially to DIYaudio Members.
A gain of 1times equals a dB ratio of 0dB
A gain of more than 1times is a +ve dB value
A gain of less than 1times is a -ve dB value.
eg 10times equals +20dB
divide by 10 = 0.1times equals -20dB
inverting or non-inverting don't affect the ratio and so they don't show as different in the dB value. One needs to tag on "inverting" to avoid ambiguity.
The formula for those few that want to be able to work it out is:
Gain = 20*log{V/Vref} and also = 10*log{Power/Pref}
Note that dB is a ratio. It must be referred to a reference.
dBV is referred to 1V
dBW is referred to 1W
dBu is referred to ~0.7747Vrms
There are lots of others, but like dBu, I have to look it/them up.
A gain of 1times equals a dB ratio of 0dB
A gain of more than 1times is a +ve dB value
A gain of less than 1times is a -ve dB value.
eg 10times equals +20dB
divide by 10 = 0.1times equals -20dB
inverting or non-inverting don't affect the ratio and so they don't show as different in the dB value. One needs to tag on "inverting" to avoid ambiguity.
The formula for those few that want to be able to work it out is:
Gain = 20*log{V/Vref} and also = 10*log{Power/Pref}
Note that dB is a ratio. It must be referred to a reference.
dBV is referred to 1V
dBW is referred to 1W
dBu is referred to ~0.7747Vrms
There are lots of others, but like dBu, I have to look it/them up.
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Don't let this discourage you, but...
We tried the B1 against the Aleph P (or 1.7?) this weekend on F5T monos. The owner of the F5T and Aleph P thought the B1 was more open and less congested. The B1 was only powered on for 5 minutes. It wasn't even warmed up.
Maybe it's good that you build the Aleph P and later a B1 and see the evolution for yourself. It's the only way to know unless you know someone with all these preamps.
Good Luck!
What was wrong with yours.
Nothing was wrong with my B1.
I also tried different MKP/MKS input and output caps in my example.
Power amps I tried them with were the Emotiva UPA-200, Adcom GFA-535II, Adcom GFA-5300 and one of the Crown XLS-series Class D amps.
For me, there was no comparison.
Perhaps the OP should build both and compare them for himself. As with most threads asking for opinions, there's always going to be some folks who prefer "A" over "B" and vice versa.
vdi_nenna,
thanks for the comments! they evaluated it on the full range though?
I was only wondering about the bass performance since I really could do without the added gain and consider a passive choice. 30uF of (expensive) film caps at AlephP's output suggests a low enough knee point for the HP filter on the bottom of the audio range for bass signal to make it out, but still, it made me wonder about what to expect for the punch??; (well, I guess I can always use miniDSP to change that bottom though; isn't it amazing how we are allowed to cheat now?).
but you are right, there will always be "an evolution", for better or worse
thanks for the comments! they evaluated it on the full range though?
I was only wondering about the bass performance since I really could do without the added gain and consider a passive choice. 30uF of (expensive) film caps at AlephP's output suggests a low enough knee point for the HP filter on the bottom of the audio range for bass signal to make it out, but still, it made me wonder about what to expect for the punch??; (well, I guess I can always use miniDSP to change that bottom though; isn't it amazing how we are allowed to cheat now?).
but you are right, there will always be "an evolution", for better or worse
Yes. Full-range in both sense of the word.
It was used on 6 ft tall Sound Lab ESLs.
Cap choice is important. Try Russian NOS types over larger caps. Some are paper in oil and others Teflon.
By bypassing with better caps I was able to get more bass out of my 6 inch dayton full range speakers.
It was used on 6 ft tall Sound Lab ESLs.
Cap choice is important. Try Russian NOS types over larger caps. Some are paper in oil and others Teflon.
By bypassing with better caps I was able to get more bass out of my 6 inch dayton full range speakers.
The DCB1 looks pretty interesting. The best cap is no cap. I'd go that route over the upgrading the stock B1. It might be even cheaper to build compared to buying good teflon 10uf caps or whatever. And the Salas shunts are real good based on what I've heard from the Salas phono stage.
But I believe in Nelson's original B1 article he said the B1 was relatively uneffected by power supply quality...I think he even used a switch mode wall wart. Makes sense since you are not really amplifying the noise. Might be a different scenario with the bipolar supply in the DCB1.
But I believe in Nelson's original B1 article he said the B1 was relatively uneffected by power supply quality...I think he even used a switch mode wall wart. Makes sense since you are not really amplifying the noise. Might be a different scenario with the bipolar supply in the DCB1.
I build the original version of the B1 and used first two 9V battery packs. The sound was very good. I wanted to show it to some friends, before I went to them I changed the battery packs against a wall wart.
My proudness was gone away completetely when we started to hear music.....dull, bad dynamics.
So I would say some wall warts do the job, some not......
BTW I like only the B1 with the caps Nelson used. You can see them in the reviews or in his article.
One of the experiences that the cap sound was better for me.
My proudness was gone away completetely when we started to hear music.....dull, bad dynamics.
So I would say some wall warts do the job, some not......
BTW I like only the B1 with the caps Nelson used. You can see them in the reviews or in his article.
One of the experiences that the cap sound was better for me.
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I have one on my table that was lent me by a board member here and member of my local area audio group. He's been patient about getting it back. Thanks Dave!
Needs a transformer and volume control to work.
It's getting colder here so I'll be trapped inside more often. Maybe them.
I originally had mine with (2) 9 volt batteries, and changed to a notepad power supply. I have built, but not implemented yet, the power supply 6L6 showed in his build guide. Noting a lack dynamics (with F5) and less full sound on amps with more gain, I parked it in favor of a tube unit.
Looking for that power supply suggested by 6L6, I have come upon a BA-3 board and parts......hmmmm
Russellc
The B1 PSU in my build was a single rail of the Peter Daniel PSU board.
For a BA-3pre, you will need both rails of the Peter Daniel PSU. (Or something else bipolar, the Didden super reg will work, with a couple of tweaks to run with 24V rails. Or the Broskie I used, or a number of different solutions. You could point wire a 317/337 if you wanted, they work really, really, really well with 220uF cap across the Adj-Gnd resistor)
For a BA-3pre, you will need both rails of the Peter Daniel PSU. (Or something else bipolar, the Didden super reg will work, with a couple of tweaks to run with 24V rails. Or the Broskie I used, or a number of different solutions. You could point wire a 317/337 if you wanted, they work really, really, really well with 220uF cap across the Adj-Gnd resistor)
TNT Audio magazine ran a series of articles regarding regulated power supplies.
At the end of the article, they tested batteries as well. Some of the power regulators had less noise than batteries. I think the alkaline batteries had the least noise.
It's on page 4. Simple Voltage Regulators Part 1: Noise - [English]
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