Buffered volume control.

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pre65
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#1 Buffered volume control.

Post by pre65 »

I've been having "issues" with my two best preamps, and my back up valve pre is not really good enough for the main system.

I was going to try a passive pre, but having read of their pitfalls, and not having time to DIY a passive with a buffer I looked to Ebay. :)

I purchased a simple device from a Chinese supplier, a 12v 2 valve buffer with volume control and it was £19:99 inc postage. It came this morning, and I'm using it now. Out of the box it sounds good, and when it's run in I might rig up a better 12v supply than the standard wall wart.

It says the two valves are 6J1, so there might be mileage in getting better quality items, but it will do for now.

http://www.ebay.co.uk/itm/NEW-DC12V-Aud ... 2749.l2649
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#2 Re: Buffered volume control.

Post by Ant »

One of the go to buffer circuits is the Nelson pass b1, this is supposed to have none of the disadvantages of a normal passive; I.e the variable output impedance.
I keep meaning to try one out.
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pre65
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#3 Re: Buffered volume control.

Post by pre65 »

Has anyone here had the chance to compare the Pass B1 with the Broskie ACF ?

I'm liking what this £20 bit of kit is doing. :D
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pre65
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#4 Re: Buffered volume control.

Post by pre65 »

Doing some internet searches on the ACF, it seems I did a breadboard version in 2013 and documented it on this forum.

I'd completely forgotten about that. :?

Seems strange reading about something I've made and forgotten about. :lol:
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#5 Re: Buffered volume control.

Post by pre65 »

This morning I'm playing disc 2 of a 4 disc set " The magical world of James Last" and enjoying it very much.

I'm thinking of words to describe how this £20 piece of Chinese crap can make my humble system sound so good, and having re-read two old threads on here re passives and buffers I'll nick some appropriate phrases that apply.

"instead replaced by a fuller mid range and more natural top end. bass has filled out as well"

"the whole sonic picture is now just very natural"

"for me its strengths are vocal articulation and dynamics and scale. The dynamics on a dynamic track are staggering."

So, mightily encouraged by the result, I need to consider the future. Ant mentioned the Pass B1 buffer, but there is a DCB1 (direct coupled version with regulators) version on DIY Audio, and seemingly it's much preferred to a normal B1.

I'll start a new thread on the DCB1 when I've done more research.
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#6 Re: Buffered volume control.

Post by pre65 »

What I really like is the lack of fatigue I'm getting.

I used to suffer from "transistor ear" after a while in the past with a "full" presentation, but (so far :) ) I've not been affected.

The thread on DIY Audio on the DCB1 Mezmerize version (6 input with relays) is linked below, and I have enquired if PCBs are still available.

http://www.diyaudio.com/forums/pass-lab ... hread.html
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#7 Re: Buffered volume control.

Post by Ant »

Id be interested if they are available too phil, the b1 and variants are what alot of people recommend for the f5
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Ray P
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#8 Re: Buffered volume control.

Post by Ray P »

pre65 wrote: Sat Sep 02, 2017 12:20 pm The thread on DIY Audio on the DCB1 Mezmerize version (6 input with relays) is linked below, and I have enquired if PCBs are still available.

http://www.diyaudio.com/forums/pass-lab ... hread.html
Check out the DIY Audio store Phil - https://diyaudiostore.com/collections/p ... -b1-buffer

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#9 Re: Buffered volume control.

Post by Ray P »

DIY Audio member 'Tea-Bag' still has a single input 'hot-rod' version available too, PCBs and/or kits.

http://www.diyaudio.com/forums/swap-mee ... -kits.html

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pre65
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#10 Re: Buffered volume control.

Post by pre65 »

Thanks Ray, It was "teabag" that I was in contact with.

I'm debating whether to go for the six input version, or a single input and separate switching box.

Seems running them at 200ma is better than normal, without the large heatsink complications of the higher current versions.
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#11 Re: Buffered volume control.

Post by simon »

Ray P wrote: Sun Sep 03, 2017 9:27 am He's a good guy.
+1
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#12 Re: Buffered volume control.

Post by JohnG »

Thank you for this recommendation
I,m just about to purchase a less than £20 device based on the Musical Fidelity X10-D schematics. Looks like a good option to have a valve output stage.
It should also drive the poweramp direct as I am doing with the CD Player.
Could this also have a Phonostage connected to it, so it could be used as volume control ?
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#13 Re: Buffered volume control.

Post by Mike H »

Image Watching.

I did one with JugFET o/p stage, but turned out it wasn't very good.
 
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#14 Re: Buffered volume control.

Post by DSJR »

JohnG wrote: Sun Sep 03, 2017 1:24 pm Thank you for this recommendation
I,m just about to purchase a less than £20 device based on the Musical Fidelity X10-D schematics. Looks like a good option to have a valve output stage.
It should also drive the poweramp direct as I am doing with the CD Player.
Could this also have a Phonostage connected to it, so it could be used as volume control ?

I have an X10-D here. The stock article coloured the sound hugely, but back then it mellowed out the scratchy '5 Star' Marantz '63KI' CD players we sold by the bucketload at the time. I long ago did a Rock Grotto upgrade, built a large 12VAC adaptor for it and fitted the better valves he supplies. The results were far less sonic intrusion when it was connected, but then, what's the point when the theoretical advantage doesn't seem to matter in practise...
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pre65
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#15 Re: Buffered volume control.

Post by pre65 »

Still happy with the pre/buffer, and no inclination to try and build something better. :D
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