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GB Group Buy Salas UltraFSP RIAA

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After significant amounts of design and testing, we are announcing a group buy for a revised Salas Folded Simple Phono preamplifier.

The power supply has been updated for the UltraBIB type, 1.3S. The S being for Special application in supporting only higher voltages. It keeps the voltage very steady at 28-36volts, depending on gain needs.

Also, additional switch banks are provided to making gain changes much easier. This can allow with a few switch settings and voltage adjustments to change the gain signature and use a different cartridge.

The signal portion remains otherwise the same as the legacy FSP. Schematics for UltraFSP

The BOM is provided here.
UFSP BOM

There is significant cost associated with the boards, the transistors and parts for the kit. If you are a previous owner of the previous Salas FSP, you can reuse your signal transistors as needed as well as signal caps.

However, I will be offering kits as well. I realize that we are in the midst of ... supply chain problems, postal delays, lost wages and more. Please be mindful I will do my best to provide boards and parts as best as I possibly can, but substitions and other matters may come up, which I will try to communicate.

To the meat of it.

UFSP Board cost 58.00 a pair.


RAW power supply, 15.00 (shown with optional parts kit)


Minikit costs, include MSRP of mouser parts, + packing and paypal fees. 55.00

Includes matched C1 and C2, plus C2Y trimmer caps. Matched Q3 and Q7.
See BOM link above.

Big Parts Kit, including minikit - 185.00.


Big Parts kit does not include below
Full Parts Kit for RAW PS - 44.00

2SK369BL matched Pair, for high gain settings, all except low MC - 12.00 R1 included for IDSS.

2SK369BL matched Quad, for LOMC Gain settings - 26.00 R1-R2 included for IDSS. (See BOM Spreadsheet TAB for 2SK369BL)

2SK170BL - triple Pairs for Q4-Q6. Includes resistors R8 and R11 based on IDSS of Q4, Q5. 36.00

Above Jfets, one set per pair of boards sold

max.


https://docs.google.com/document/d/1ip_eB3CbCMnZqCa7Nrlpsx4D9TfRMBJnN2GqJsKhqFE/edit




 
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new boards are 152mmx107mm for one channel. But PS part is v-scored an can be removed. The prior board was discussed as two channels. I can try to measure side by side later for those interested in using same space.

Here is the old vs new board for sizing.
The old board measures at 140mm x 95mm
 

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So, Have I got this correct? I use the 1.3S for that voltage range but I can use my existing 1.3 for the lower voltage range. And, only one needed cause it has both channels. But, if I want to I can just use a raw power supply? Why would I want to do that since the UBib1.3 has such great reviews?

I signed up. Hopefully if it doesn't make sense Tea will message me. Thank you both for this.

Don
 
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So, Have I got this correct? I use the 1.3S for that voltage range but I can use my existing 1.3 for the lower voltage range. And, only one needed cause it has both channels. But, if I want to I can just use a raw power supply? Why would I want to do that since the UBib1.3 has such great reviews?

Glad you mentioned this.
This is incorrect, so it's worth pointing out. There is no build guide yet, so the original FSP serves as a precedent.

The raw supply is occasionally in a separate box, but is effectively a pre-filter and ground end point in one. Do AC/DC here.

The 1.3S. has no AC/DC. It adds two zeners here to keep the voltage up.

We did the earlier protos with standard UBIB. The problem is that a little voltage drop at warm up with the UBIB standard made setting the testpoint on the phono board not difficult, but time consuming. So this was altered to allow the voltage to remain pretty rock solid, and not drift from turn on to many hours. Plus, it's built onto the board, but can be broken off as well.
 
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The 1.3S (S for special) is the Ubib shunt reg section of the phono for working steadier at the phono's rail voltage range. DC input only and outputs from 28V up to 38V only. Has a couple of opposite going Zeners for stabilizing drift and augmented local filtering. To help easier TP setting of the phono. Because the 2SK369s input stage when in LMC or MC setting has the tendency to drift along the same way with the regular Ubib 1.3.

The regular Ubib 1.3 outputs from 5V-40V. But its optimized for drift in the 5-25V lower output range. For the vast majority of general applications. Most of them don't care for small thermal drift anyway. It could take a Zener mod but its bulkier also as it has rectification bridge and Quasimodo network which go along with a transformer and we don't want a transformer's hum field in the phono box. We put the Raw PSU board and the transformer(s) in another box.

In other words we could use a classic Ubib but I developed a most right Ubib tweaked for this very job. Comes as standard attached to the phono PCB along a score line. No worries.
It can either stay attached or break away to be arranged otherwise somewhere near in the box. Say phono channels in the middle and 1.3s sections along the side panels if someone has a narrow box.
 
Not to touch smb. on a raw spot, but do we have any plan to add Capacitor Multiplier to the RAW DC PCB? Also, wold be nice to add possibility and include transformers snubbers. Based on some feedbacks, such RC snubbers are not that important when constant current draw is used, but any way, it is nice to have such optimal feature.
 
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I have an original unbuilt FSP kit that I have been working towards by building a few simpler phonos first.

I’m pretty sure I have everything. Possibly not the extra JFETs to build it specifically for low output.

That is because I wanted the flexibility of using it with both MM and MC carts and I have a high quality JFET MC head amp I can switch in and out in front of the FSP to allow for an additional 20dB of gain.

It seems like this “Ultra” version has addressed the issue of adjustable gain and also improved the power supply.

Are there certain parts of the package I can buy to use with my original FSP kit so that I can benefit from some of the improvements?

I’m thinking maybe the power supply? But it seems like the variable gain would require new boards?

BTW...I tried viewing the spreadsheet order form. For some reason it won’t open for me on my iPhone in Sheets.