AKSA's Lender Preamp with 40Vpp Ouput GB

[Harry3]

Hi X
I received the boards that you sent, thanks.
I also bought two DC to DC step up boards.

Need to finish off my Slewmaster amp and move house

 

[xrk971]

Hi Harry3,

You only need one DC step up for one main board for stereo.

Thanks for the update.

X

 

[xrk971]

Thanks, X, for the MELF example. Any chance to measure yet?


BK

Here are the measurements...

20Vpp into 7kohm load (about 23ppm THD):

4.0Vpp into 7kohm load (about 7ppm THD):

It looks pretty clean. The gain is set at 20dB for this case as JPS64 did not send me a 12k MELF for the FB resistor. I am using 10R degeneration resistors on the LTP.

Here's the clincher though, the thread title is 40Vpp output. I had to raise the Vcc to 50v but here it is... only 64ppm THD and the profile looks glorious.

So let's push this amp to just before clipping and see what it can do, well, if you run Vcc at 59v, it can push out 51.4Vpp with 0.013% THD:

That's pretty darn good and enough to mae 41wrms into 8ohms assuming your current buffer amp can keep up.

 

[AKSA]

Lovely work, X! This is a very impressive performance using bare bones circuitry, no CCS on the LTP even which according to Self is essential....
It's interesting that 40Vpp to 51.4Vpp only double distortion, but maintained the profile.
Terrific measurements, thanks for sharing all this.

Ciao,

Hugh

 

[xrk971]

Hi Hugh,
Well, it’s your design that makes it all work. I think it may be, the fact that it is so bare bones and simple that the harmonic distortion profile looks so simple. I am thinking maybe I only build output stages from now on and connect this preamp in front of everything? Why mess around with another input stage when this works so well.

 

[press57]

GB3 still open if,put me in for a 1 set of TH boards.

 

[xrk971]

GB Status Update...

GB #2 Closed
Thimios - 1 set SMT, Paid
Pinnocchio - 1 set SMT, Paid
Mituisho - 1 set SMT, Paid
Alurudin - 1 set TH, Paid
*muthumuthiah - 3 sets all TH, ship all with order from GB #1, Paid (special address?)
jwjarch - 1 set TH, Paid
jwjarch - 1 set of TH daughterboards only, Paid
jwjarch - 1 set SMT 0805/1206 (shipment to be combined with above), Paid
briansz - 2 set TH, Paid
steefdebruijn - 2 sets TH + spare set SMT daughterboards, Paid
jmc207 - 2 sets: 1 TH and 1 SMT; +1 spare set TH daughterboards, Paid
marcus22ch - 2 sets SMT, Paid
vanofmonks - 1 set TH, Paid
pfisl - 1 set TH, Paid
neoinc - 1 set TH, Paid
redarc12 - 1 set of TH daughterboards only, Paid
gtose - 1 set SMT 0805/1206 version, Paid
Vunce - 1 set TH plus 1 spare set of TH daughterboards, Paid
Malvin - 1 set SMT 0805/1206, Paid
arthur - 4 sets, 2 TH & 2 SMT, Paid
cowneko - 1 set SMT 0805/1206, plus DZT5401 & fjv1845 set, Paid

---- List for GB #3 - Still Open ----
*nania - 1 set SMT, Invoice sent - need payment please
Pierre QuiRoule, 1 set TH, Paid
jugi63, 1 set TH, Paid
bk856er, 1 set TH, Paid
ft0601, qnty 2 complete sets TH, Paid
*press57, Please send PayPal address

All boards packed, ready to ship once task of printing shipping labels is completed.

 

[Skip Pack]

JPS64 - 2 sets w/ SMT daughterboards
Algar Emi - 1 set, SMT or TH?
Redarc12 - 1 set, SMT or TH?
CFT - 1 set, SMT or TH?
Jacques Antoine - 1 set TH
Silasmellor - 1 set THT
Bvtrinh- 1 set TH
ggetzoff - 1 set TH
tubesguy - 1 set TH
Aatto - 1 set SMT
Mordikai - 1 set TH
Johnny2Bad 1 set TH; 1 set SMT
Skip Pack 2 sets TH

I didn't see a protocol for further communications (payment, shipping addr . . .) Please let me know how you are working this one.

Thanks, Skip

 

[xrk971]

I didn't see a protocol for further communications (payment, shipping addr . . .) Please let me know how you are working this one.

Thanks, Skip

Did I somehow missed seeing your name on GB 1? Sorry about that. You are just in time for this latest GB2/3. Please pm me your PayPal address and I will send you invoice. I will send packages out this Fri.

 

[xrk971]

GB Status Update

GB #2 Closed
Thimios - 1 set SMT, Paid
Pinnocchio - 1 set SMT, Paid
Mituisho - 1 set SMT, Paid
Alurudin - 1 set TH, Paid
*muthumuthiah - 3 sets all TH, ship all with order from GB #1, Paid (special address?)
jwjarch - 1 set TH, Paid
jwjarch - 1 set of TH daughterboards only, Paid
jwjarch - 1 set SMT 0805/1206 (shipment to be combined with above), Paid
briansz - 2 set TH, Paid
steefdebruijn - 2 sets TH + spare set SMT daughterboards, Paid
jmc207 - 2 sets: 1 TH and 1 SMT; +1 spare set TH daughterboards, Paid
marcus22ch - 2 sets SMT, Paid
vanofmonks - 1 set TH, Paid
pfisl - 1 set TH, Paid
neoinc - 1 set TH, Paid
redarc12 - 1 set of TH daughterboards only, Paid
gtose - 1 set SMT 0805/1206 version, Paid
Vunce - 1 set TH plus 1 spare set of TH daughterboards, Paid
Malvin - 1 set SMT 0805/1206, Paid
arthur - 4 sets, 2 TH & 2 SMT, Paid
cowneko - 1 set SMT 0805/1206, plus DZT5401 & fjv1845 set, Paid

---- List for GB #3 - Still Open ----
*nania - 1 set SMT, Invoice sent - need payment please
Pierre QuiRoule, 1 set TH, Paid
jugi63, 1 set TH, Paid
bk856er, 1 set TH, Paid
ft0601, qnty 2 complete sets TH, Paid
press57, 1 set TH, Paid
*Skip Pack, 1 set TH, Invoice sent

 

[schlomoff]

pre

hello x, I received the boards, top.I will take a new set of boards TH thank you dence

 

[xrk971]

Hi Schlomoff,

You would like another set of TH daughterboards only or a complete set with motherboard?

 

[schlomoff]

Hi Schlomoff,

You would like another set of TH daughterboards only or a complete set with motherboard?

complete merci

 

[xrk971]

GB Status Update

GB #2 Closed
Thimios - 1 set SMT, Paid
Pinnocchio - 1 set SMT, Paid
Mituisho - 1 set SMT, Paid
Alurudin - 1 set TH, Paid
*muthumuthiah - 3 sets all TH, ship all with order from GB #1, Paid (special address?)
jwjarch - 1 set TH, Paid
jwjarch - 1 set of TH daughterboards only, Paid
jwjarch - 1 set SMT 0805/1206 (shipment to be combined with above), Paid
briansz - 2 set TH, Paid
steefdebruijn - 2 sets TH + spare set SMT daughterboards, Paid
jmc207 - 2 sets: 1 TH and 1 SMT; +1 spare set TH daughterboards, Paid
marcus22ch - 2 sets SMT, Paid
vanofmonks - 1 set TH, Paid
pfisl - 1 set TH, Paid
neoinc - 1 set TH, Paid
redarc12 - 1 set of TH daughterboards only, Paid
gtose - 1 set SMT 0805/1206 version, Paid
Vunce - 1 set TH plus 1 spare set of TH daughterboards, Paid
Malvin - 1 set SMT 0805/1206, Paid
arthur - 4 sets, 2 TH & 2 SMT, Paid
cowneko - 1 set SMT 0805/1206, plus DZT5401 & fjv1845 set, Paid

---- List for GB #3 - Still Open ----
*nania - 1 set SMT, Invoice sent - need payment please
Pierre QuiRoule, 1 set TH, Paid
jugi63, 1 set TH, Paid
bk856er, 1 set TH, Paid
ft0601, qnty 2 complete sets TH, Paid
press57, 1 set TH, Paid
*Skip Pack, 1 set TH, Invoice sent
*Schlomoff, 1 set TH, Invoice sent

 

[muthumuthiah]

Hi X
I sent you a PM regarding my postal address.
Cheers
MM

 

[xrk971]

Hi X
I sent you a PM regarding my postal address.
Cheers
MM

Can you please resend? Thanks.

 

[xrk971]

My Mouser order just showed up so now I have all Wima/Nichicon/Elna Silmic for the caps. I also got the correct pot but unfortunately ended up getting the SMT version of the X121 jack for the 8-pin ribbon cable. Need to double check the BOM for the correct part number. Anyhow, this is going to be a nice preamp now fully loaded with name brand caps. The triple 4700uF 63v Nichicons on the CRCRC are definitely a nice touch as power supplies go. I don't think you will find a quieter PSU for a similar level of low complexity here (1 MOSFET for the cap Mx). Just checking the fit here and thought I would share this beauty shot when loaded with the "good stuff". The Elna Silmic II 220uF 50v and Wima 1uF 250v on the outputs should be particularly great here. I am running a 4.7uF 100v Wima MKS on the input sitting where the electrolytic would go. I think 4.7uF should be plenty of bass extension considering input impedance is 47kohm. Also using Wima 220pF 100v MKS for the input RFI filter. Will be sure to use all carbon film resistors on the input signal path and critical parts of the output and feedback.

 

[xrk971]

GB Status Update

GB #2 Closed
Thimios - 1 set SMT, Paid
Pinnocchio - 1 set SMT, Paid
Mituisho - 1 set SMT, Paid
Alurudin - 1 set TH, Paid
*muthumuthiah - 3 sets all TH, ship all with order from GB #1, Paid (special address?)
jwjarch - 1 set TH, Paid
jwjarch - 1 set of TH daughterboards only, Paid
jwjarch - 1 set SMT 0805/1206 (shipment to be combined with above), Paid
briansz - 2 set TH, Paid
steefdebruijn - 2 sets TH + spare set SMT daughterboards, Paid
jmc207 - 2 sets: 1 TH and 1 SMT; +1 spare set TH daughterboards, Paid
marcus22ch - 2 sets SMT, Paid
vanofmonks - 1 set TH, Paid
pfisl - 1 set TH, Paid
neoinc - 1 set TH, Paid
redarc12 - 1 set of TH daughterboards only, Paid
gtose - 1 set SMT 0805/1206 version, Paid
Vunce - 1 set TH plus 1 spare set of TH daughterboards, Paid
Malvin - 1 set SMT 0805/1206, Paid
arthur - 4 sets, 2 TH & 2 SMT, Paid
cowneko - 1 set SMT 0805/1206, plus DZT5401 & fjv1845 set, Paid

---- List for GB #3 - Still Open ----
*nania - 1 set SMT, Invoice sent - need payment please
Pierre QuiRoule, 1 set TH, Paid
jugi63, 1 set TH, Paid
bk856er, 1 set TH, Paid
ft0601, qnty 2 complete sets TH, Paid
press57, 1 set TH, Paid
Skip Pack, 2 sets TH, Paid
Schlomoff, 1 set TH, Paid

 

[prasi]

Hi xrk,
Boards received, thank you. They look amazing and very nice design by JP.

regards
Prasi

 

[Johnny2Bad]

The tools mentioned look great, especially if you are in need of a fast production-level workflow; I just found a video (38 minutes) on YouTube that I found extremely informative wrt SMD soldering with relatively basic tools and supplies. It's good enough that I recommend everyone in this thread to check it out.

Oh, and don't waste your time reading the comments; they are juvenile and of no value, and it doesn't get better if you drill down. I couldn't see any posts where he replied, so no answers there anyway.

One thing he doesn't mention is the composition of the flux cleaner he uses with the acid brush (it will make sense after you view it), but my guess is it's the same 50:50 acetone / alcohol mix he uses in another segment.

Sparky's Widgets: How To SMD Soldering