best pre-amp for Pass F6

[fabrice63]

Hi everyone,

I am looking for an nice great pre-amp to boost my Philips IS-5021 output , before my F6.


The DAC analog output is about 1 v rms , impedance is 200 ohms.


something simple , one in one out , dead quite , some noble stuff that some of you guy's know's about 😀


Tanks in advance


Fabrice


.

 

[vdi_nenna]

Listed are some simple preamps. There are others, so look around.

I have used BOZ-J and B1 with the F6. BOZ-J has gain, 1 jfet in the path and 1 10uF cap in the output. B1 no gain.

BOZ-J has a little more in the way of bass support than the B1. The B1 is a little more transparent.

Also, there's a B1 rev2 that has no caps in the path.

B1- http://www.diyaudio.com/forums/pass-labs/124889-b1-buffer-preamp-418.html

BOZ-J- see post 2. 10 ohm resistor should be 22 ohm with a 16v power supply, but 10 ohm will still work.
http://www.diyaudio.com/forums/pass-labs/103050-jfet-boz.html

B1 rev2 - see attached.

Vince

 

[xrk971]

Best is a matter of debate and subjective. There are preamps that use 30+ actives per channel with exceedingly low distortion. But is that consistent with Pass Fx amp philosophy?

This one is very simple and just about every circuit from Juma works very well without fussing.

I just built this one and it sounds superb.

http://www.diyaudio.com/forums/pass-labs/146310-bf862-preamp-43.html#post4918316

Single ended class A with gain adjustable from 6dB to 17dB. Silent and super transparent.

 

[vdi_nenna]

What type of surface mount resistors are on your board?

 

[xrk971]

0805 metal thin film 1% (maybe 5% but measure within 1%)

 

[2 picoDumbs]

Zen Mod's KISS

 

[2 picoDumbs]

Best is a matter of debate and subjective. There are preamps that use 30+ actives per channel with exceedingly low distortion. But is that consistent with Pass Fx amp philosophy?

This one is very simple and just about every circuit from Juma works very well without fussing.

I just built this one and it sounds superb.

http://www.diyaudio.com/forums/pass-labs/146310-bf862-preamp-43.html#post4918316

Single ended class A with gain adjustable from 6dB to 17dB. Silent and super transparent.

Yes that is a nice preamp.

 

[fabrice63]

The jeft-BOZ looks interesting, but where to find some genuine matched 2sk170 bl ??

I have some nice 14.8 v / 6 A lipo battery for it ;-)

.

 

[fabrice63]

is the LSK 170 from the store the same as the 2sk170bl ??

.

 

[bk856er]

The jeft-BOZ looks interesting, but where to find some genuine matched 2sk170 bl ??

I have some nice 14.8 v / 6 A lipo battery for it ;-)

.

Could try here?

BK

 

[2 picoDumbs]

is the LSK 170 from the store the same as the 2sk170bl ??

.

Yes

 

[Soundhappy]

Control Volume with Light

Work with DAC , CD-players or audio cards if output gain is sufficient.
Maybe try first put some simple carbon potentiometer directly from source to amplifier to attenuate signal not preamplify ?
Switch with individual resistors , Autoformer Volume Control

http://www.intactaudio.com/module.html

or Transformer Volume Control all of this are interesting
sonic way to explore for passive friendy amplifier with his source & speakers.

What about this solution presented by Papa ?
Volume control with jfet buffer by light & resistors vactrol
so no physical contacts in audio path like switch or potentiometer.
Copyright and schematic courtesy by Mr Nelson Pass

http://www.diyaudio.com/forums/anal...uator-new-passive-preamp-133.html#post1520215

 

[fabrice63]

I dont want to attenuate the DAC output , i dont want the DAC volume to be at 100 % , it work great at - 8db on it's scale ( the lowest distortion point ).

i want some gain ;-) , with the less components as possible ;-)


.

 

[vdi_nenna]

The jeft-BOZ looks interesting, but where to find some genuine matched 2sk170 bl ??

I have some nice 14.8 v / 6 A lipo battery for it ;-)

.

I'm currently using the BOZ-J with a single-ended input, 15w Aleph.
I'm always amazed by the sound when casually listening to this setup.
It's an engaging sound. Draws you in and makes you listen.
BTW- using this with Volumio music server and Gungnir delta/sigma USB DAC, not new multi-bit version.

The jfets are available in the DIYAudio Store.

 

[Zen Mod]

I believe Iron Pre SE will suffice , as proper one

and , little later , Iron

OK, I'm biased ......

 

[Soundhappy]

.....
i want some gain ;-) , with the less components as possible ;-)


.

Ok you have DAC with volume potentiometer knob and if connected directly to F6 they need some gain anyway ?
Jfet buffer are great no doubt if necessairy.

Personally i don't use preamplifiers any more transistored or triodes
i change for autoformer volume control 🙂
i like gain up stages like was used in M2 with Edcor.
Smaller number of semiconductors in delicate audio signal path.

Really minimal "preamp" ?

just wire on core + 6 dB with transformer volume control

SAC Thailand

Maybe this is not your taste game but i share my great discoverings 🙂

Zen Mod preamp KIS can be new champion as well
Enjoy & kindest regards

 

[Soundhappy]

I dont want to attenuate the DAC output , i dont want the DAC volume to be at 100 % , it work great at - 8db on it's scale ( the lowest distortion point ).

Do you know your DAC analog gain stages are op-amp's ? Volume knob are digital encoder ?
Audio source DAC or CD-player with pure single-ended or push-pull stages
in class A after digital circuit that logic choice for class A F6 amplifier.
Op-amp can have strange harmonic content so if you give them more gain that non garantie it's sound fantastic
I know this situation from my past conclusion non class A glory without adequate DAC or CD-player.
On the photo my actual single-ended CD-player work great without classic preamp in the audio chain.

 

[Zen Mod]

AVC or TVC alone , can be standalone , if all puzzles are well placed (Rout of preceding stage , friendly interconnects etc.)

but , integrated in properly made package (good enough buffer and good enough PSU for it) , that's notch or two upped game

plenty of possible solutions , not just mentioned Iron Pre (drekload of details in thread)

in my opinion , speaking of AVC (I prefer it to TVC , when galvanic isolation isn't needed ) , pretty best bang for the buck is Intact audio 200$ offer

I also prefer those to their later ones (shebang with two rotary switches)

 

[poseidonsvoice]

AVC or TVC alone , can be standalone , if all puzzles are well placed (Rout of preceding stage , friendly interconnects etc.)

but , integrated in properly made package (good enough buffer and good enough PSU for it) , that's notch or two upped game

plenty of possible solutions , not just mentioned Iron Pre (drekload of details in thread)

in my opinion , speaking of AVC (I prefer it to TVC , when galvanic isolation isn't needed ) , pretty best bang for the buck is Intact audio 200$ offer

I also prefer those to their later ones (shebang with two rotary switches)

This (but my implementation is expensive, max gain of +7dB): Poseidon's Voice Lazarus

This...with stupendously good measurements, and a default gain of +6dB: Differential Preamp 8×2 – Neurochrome :: Audio

This...if no gain is required: LDR3.V2K Passive Preamp Kit | Tortuga Audio

This...if you love DHT tubes and just a little gain:http://www.kandkaudio.com/single-ended-line-stage-preamps/

Best,
Anand.

 

[Zen Mod]

mine are members of MYB approach group of products

in fact , all gadgets I've made are