AKSA's Lender Preamp with 40Vpp Ouput GB

[xrk971]

I am starting to ship now. There are still a few sets left if you are interested.

It sounds great and measures very well. Like a muscular Aksa Lender Preamp that can drive 8ohm loads.

 

[MShipmanPE]

PM sent

 

[MShipmanPE]

X

Just a reminder:

1 set TH AKSA’s Lender preamp boards
1 set AKSA Lender PMOS Hybird Aleph 20 watt boards
Ship together
Paid $25
Need invoice for remaining balance.

Thx

 

[xrk971]

Mshipman,
Ok just sent you invoice.

 

[Vunce]

Hi X,

My current daughter boards have 12k resistors in R10 to use with my MoFo amp.
I am assembling another set of DB’s to use with a tube amp that has 20db of gain on its own. Can I use 3.3K or lower in R10 to significantly lower the gain?

Vunce

 

[xrk971]

Hi Vunce,
Yes, changing R10 to 3.3k will give you 10.4dB gain, which is in general on the low side even when driving a 20dB amp. I would go a bit higher with 3k9 for 14dB gain on the Aksa Lender pre. Here is a trick: solder R10 sticking out the back side all on its own so you can easily swap it out.
X

 

[Vunce]

Thanks X

 

[MShipmanPE]

Have boards in hand.

Thanks X

 

[Vunce]

While waiting for components to arrive for my ALPHA20 project, I assembled a set of daughter boards to lower the gain in my AKSA Lender preamp. The original set used 12K ohm resistors in R10 and worked great with my MoFo amplifier, but was too ‘hot’ for my 6L6 tube amp. I used 4.7K ohm for these daughter boards. The resistor change enables a much finer volume control.
I was able to position Q4 and Q5 so I could attach small heatsinks, they get pretty warm/hot.

 

[xrk971]

Nice work, Vunce. I did the same trick to get the heatsinks on opposite sides too. Those are nice coupling caps you have. Only the best here.

 

[Vunce]

Thanks X.
Believe it or not, positioning Q4 and Q5 took more time then soldering the rest of the board

 

[xrk971]

I know how that feels. I spent 4hrs one time debugging 1 daughterboard. Could not find problem and finally abandoned it to make a new one in 30minutes. Worked fine on new one. Kick myself for blowing half a day.

 

[zman01]

JPS64 MELF resistor GB

JPS64,

Hope you are feeling better.

Have you started the MELF resistor GB for SMD PCB builders? Sorry if this has already been discussed and I am asking again.

 

[twocents]

Extra boards?

Thank you X - received my boards yesterday, but a real noob question - what are these extra boards for? Don't see them in your build or Vunce's build.

 

[xrk971]

They are in the main (MB) schematic. Basically a power entry CLC filter, a Power On/Off switch holder, and a input/output panel with multi-input selector switch.

These are all optional should you need them. Some people like to have multiple inputs to a Preamp.

 

[twocents]

They are in the main (MB) schematic. Basically a power entry CLC filter, a Power On/Off switch holder, and a input/output panel with multi-input selector switch.

These are all optional should you need them. Some people like to have multiple inputs to a Preamp.

Ok, thanks. I believe you. Had one look at the schematic then immediately closed it again.

Do I need it? When to use the CLC filter for example?

 

[xrk971]

Don’t panic. Just look at the core amp circuits. The rest is just getting power to it and signal to and from.

The amp core has 5 actives - hardly anything more simple than that. 15 resistors, 4 caps, 1 diode.

 

[tome]

Hi
If any boards left, I'll take one motherboard, two TH daughter boards and two 20W ALPHA boards.
thanks
Tome

 

[xrk971]

Hi
If any boards left, I'll take one motherboard, two TH daughter boards and two 20W ALPHA boards.
thanks
Tome

There are more preamp boards but need to order Alpha 20 boards. I will add you to the GB and when boards arrive will send all to you in one shipment.

 

[tome]

OK,no problem