I’m adding an SRS PERF10 reference clock to my Vivaldi stack (what the heck – in for a penny, in for a dollar). Does anyone know if the “Reference In” setting in the Vivaldi clock menu should be set to “TTL” or “AC” for the PERF10? I did a search for the subject on this community but couldn’t find an answer.
Thanks for any help you can give me with this.
Hi Craig, welcome to the community.
It should be set for AC as the PERF10 outputs a sine-wave on it’s Clock outputs.
(From the PERF10’s Manual)
- Outputs 1-8. 75Ω BNC connectors which carry the 10 MHz output. Each output is a 10 MHz sine wave with an amplitude of 1 Vpp when terminated in 75 Ω
By the way, you might want to read-up on this thread from @PaleRider who discusses the use of the PERF10 extensively. 
Thank you so much for the quick reply!
I didn’t realize a sine wave output is the same as an AC output. I guess it’s pretty apparent electrical engineering is not my field.
I did see @PaleRider’s earlier post, but I didn’t see the answer to my question anywhere in that thread. Thanks for directing my attention to it, though – I’ll re-read his comments to see if he has any other pointers for using the PERF10.
Hello Craig and welcome. Page 18 of the Vivaldi Clock manual also implicitly states that the appropriate input is AC with its reference to use of a rubidium clock.
Hi Greg,
Thanks for the welcome, and thanks also for the reference to Page 18 of the clock manual. Yes, I missed that – I was stuck on the information at Page 13. Now I’m a bit embarrassed (but better informed, at least!).
Do you have any other tips on how to get the most out of the PERF10? Did you ever try it with a separate linear power supply, for instance?
Hey Craig, you’re not the first to miss info in the manuals; I sure did! dCS manuals are very informative, but often not intuitive. 
No real suggestions. The PERF10 is a great device, pretty much set and forget. Some here will advocate exploration of clock cables, or improved power supply [I had one built for mine by Plixir], and if you are so inclined, it could be worth your time. Otherwise, sit back and enjoy.
Thanks for the advice. I already went down the rabbit hole on clock cables for my Vivaldi stack, but I think I may try an external power supply at some point. I’ve had good success with Paul Hynes units in the past, but now that he’s gone dark, I’ll have to explore other options. I heard good things about Plixir from someone else who used to own a Paul Hynes power supply, so that sounds like an avenue worth exploring.
Hey, if you don’t mind me asking, what cables have you tried for your Vivaldi and what did you like best? I have the transparent reference (red) cables now and am thinking of upgrading to their XL range (blue)…
Hi Cleop
Are you using the Perf 10 ?
I have a Vivaldi stack
Can you describe the improvements ?
Im considering too the Mutec ref 120
tks
Hi Marcelo,
So, I’ve been a bit busy in my personal life and haven’t looked at my messages on the dCS community until just now. Sorry for the delay in getting back to you.
In case you haven’t yet pulled the trigger on an external reference clock, I do recommend the Perf10, although I haven’t heard the Mutec ref 120 for comparison. I did find adding a high-quality external LPS elevated the performance of the Perf10 even further.
Interestingly, I recently had a chance to compare the Perf10 to a CH Precision T1, which many people feel is the best external clock out there at the moment. The T1 did not have the GPS module, so I can’t say how it would compare with that included, but on its own, I felt the Perf10 and external LPS was slightly more dimensional. Obviously, your mileage may vary.
– Craig (“Cleop”)
I use a cybershaft op21 with my Vivaldi clock. Works perfectly, and still much better since I changed the clock cable.
Yes, I agree the clock cable can make a significant difference. I’ve tried a few (including, among others, Apogee, Blue Jeans Cable, Transparent, and Shunyata), but the one that’s worked best for me between the Perf10 and Vivaldi clock is from Black Cat.