Joseph, thanks for your replies. Woops! Right, so that I get this right.....eventually..... which caps should I check again to make sure I have the right values. Rob.
Hi Joseph. On the BOM I (sort of used - in conjunction with the silk screen print) the BOM suggested leaving out C17 - 20) I think this is the Clave Fremen edition recommendation?
In an attempt to cure the lack of HF and clearly having no idea as to how the circuit of my version works, about a week ago I in fact soldered the missing caps 17 - 20 on the L channel board. Of course it made no difference the HF response.
UPDATE : Today I managed to find some 150pf crappy old ceramic caps and removed the incorrect 22n caps and soldered these in. These were the only low value caps I have at anywhere near the recommended 220pf. On my test system it is of course sounding much better and the HF response is sounding good.
So...now I need recommendations as to the best type of cap to get for the C12 position. In addition I would like some advice on adding C17 - 20 to the R channel board to make the boards the same. I have to say that in my test system both channels are sounding the same...or should I remove C17 - 20 from the L channel?
Thanks in advance. Rob.
In an attempt to cure the lack of HF and clearly having no idea as to how the circuit of my version works, about a week ago I in fact soldered the missing caps 17 - 20 on the L channel board. Of course it made no difference the HF response.
UPDATE : Today I managed to find some 150pf crappy old ceramic caps and removed the incorrect 22n caps and soldered these in. These were the only low value caps I have at anywhere near the recommended 220pf. On my test system it is of course sounding much better and the HF response is sounding good.
So...now I need recommendations as to the best type of cap to get for the C12 position. In addition I would like some advice on adding C17 - 20 to the R channel board to make the boards the same. I have to say that in my test system both channels are sounding the same...or should I remove C17 - 20 from the L channel?
Thanks in advance. Rob.
I would vote for removal.. As adviced originally.
Now, in C12 there is a Wima FKP2, 220pF cap in the 'industrial' BOM of the FE versions.
But also Armtrans caps from Hificollective would be good, that is even better. While at it, it would be nice to change also C30 (1nF) for either an FKP2, or Armtrans, or some kind of Styroflex capacitor
Now, in C12 there is a Wima FKP2, 220pF cap in the 'industrial' BOM of the FE versions.
But also Armtrans caps from Hificollective would be good, that is even better. While at it, it would be nice to change also C30 (1nF) for either an FKP2, or Armtrans, or some kind of Styroflex capacitor
Yes and it is valid also for the Rev. C.
I suggest you to remove those test caps.
🙂
I absolutely second George's recommendation.
Just remember that Amtrans AMCH are way better than Wima FPK2 😉
The rest of the BOM will be the limiting factor... In case in the future you will rework your boards here is my BOM fort TP boards:
My_Ref Ultimate Rev C BOM 2.0 - Google Sheets
Brilliant. Thanks Joseph and Dario. I looked at the Hifi Collective site the other week and registered in case I needed to buy caps. I will report back in due course. Rob.
There appear to be two choices of cap at 220pf, Amtrans AMCH Polypropylene and Silver Mica (no brand name given), both the same price. Any preferences? Or maybe I should buy both flavours.
I had a good session with the amp yesterday and even with the ceramic 150pf's it sounds very good. I found some 68pf caps of the same type and added them in parallel for roughly 218pf. Doesn't sound massively different.
I have ordered some Amtrans caps in both 150pf and 220pf. Will report back once I have them. Once again, thanks to all who have replied to my posts and given advice on the problems I had. Rob.
I have ordered some Amtrans caps in both 150pf and 220pf. Will report back once I have them. Once again, thanks to all who have replied to my posts and given advice on the problems I had. Rob.
Thanks!
Thanks for the BOM Clave, I still have a spare pair of green pcb boards from my build of the rev C Ultimate 10 years ago My Ref Revision C Ultimate GB (Green Mountain Edition) | twiddlingmyknobs
I was surprised to find the Rev C seems to drive some big EV cabinets I am usually driving with a 200 W PA? I lost a channel on the PA and tried switching to the Rev C and it seems to sound OK with the big 15" EV cabs. What is the output of the Rev C?
Thanks for the BOM Clave, I still have a spare pair of green pcb boards from my build of the rev C Ultimate 10 years ago My Ref Revision C Ultimate GB (Green Mountain Edition) | twiddlingmyknobs
I was surprised to find the Rev C seems to drive some big EV cabinets I am usually driving with a 200 W PA? I lost a channel on the PA and tried switching to the Rev C and it seems to sound OK with the big 15" EV cabs. What is the output of the Rev C?
Hi, I was checking My_Ref Ultimate Rev C BOM 2.0, but I am a little bit confused. Suggested resistors got different characteristics than proposed values. For example: Resistor R2 should be 10K 1/4W with 2% tolerance, however part number is 71-RN55E-B-10K/R, which is resistor not with the power rating of 1/4W but with 1/10W. Is it ok to use 1/10W resistors instead of 1/4W?