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I'm about to order the parts for a Pete Millett Hybrid Tube amp for my DT880s, but I have a few questions. For the 100 uf and 220 uf electrolytic capacitors, would it be better to buy the high quality Elna Cerafines on the parts list, or buy larger (about 5 times the capacitance), slightly lower quality Panasonic FCs of the same diameter? Are there any other parts subsitutions that you recommend that will fit in the PCB? Lastly, will this amp sound better than my PIMETA? I really want to try out tube sound, but I'm wondering if this will turn out to be worse than my current amp.

 

[ITZBITZ]

I bought the Nichicon Muse KZ 100uF/100V units from Percy Audio as they are highly respected in the tube world. I went with 220uF Muse KZ also for the other two caps.

I haven't ordered any 0.22uF WIMA caps yet, I'm still trying to decide if I want to go that route or not. I can't think of anything else I want from Welborne Labs so it's kind of a tiny order.

I also haven't ordered tubes or sockets yet. Other than that, I'm fully soldered and ready to go!

Oh, I haven't ordered a case yet, other than that I'm fully soldered and ready to go!

Oh, I haven't installed the BUF634T's yet, other than that I'm fully soldered and ready to go!

As for sound, I have no idea. But I have the same headphones (DT880's) so I am as curious as you are about the results. I was actually thinking of using it as a preamp to my PPA, but I don't know yet.

 

[00940]

regarding c16 and c7, output caps : buy the best caps you can. 100uf is ok for high impedance cans. Below 100ohms you could want to bump those caps to 220uf.

c13 and c4 must be from the highest quality. Wima mkp is the least you can do. The other 0.22 "can" be wima mks. Mkp wouldn't hurt though.

c1, c9, c10, c18, c19 could be increased to 220uf (or higher) at first sight.

 

[slindeman]

I didn't want to order from Percy or Welborne, so for the caps I bought:

(7) 470uF 63V Panasonic FC (Digikey # P10352-ND)
(2) 220uF 35V Panasonic FC (Digikey # P10297-ND)
(8) .22uF 50V Panasonic Polypropylenes (Digikey # P3224-ND)

Note that if you buy 10 of the 470uF and the .22uF you will save money even though you only need 7 or 8 of them because of the qty discount. I believe the WIMAs are metallized polypropylene, right? I would assume the Panasonic Polyprop's might be better since they are not metallized.

Pete said the 470uF would be fine, and I would probably suggest using larger than a 100uF at least for the output cap if you use low impedance headphones or you will lose some bass. Whether the Cerafines would make a big difference over Panasonic FC I couldn't say since I've never compared them. Upgrading the output cap to a Blackgate would be a good choice, but you can always do that later.

If you are also ordering stuff from Mouser, you can save a little cash as mouser carries many of the parts that are listed on Pete's parts list from Digikey. Just do a search on the manufacturer's part number. Usually mouser is a little cheaper, but not always.

As far as on-board upgrades there isn't much you can do besides change the caps and play with the different tubes and biasing. If you go off-board you can use nicer RCA jacks, potentiometer, power supply, and case.

Hope this helps!

 

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Quote:

Originally posted by slindeman I didn't want to order from Percy or Welborne, so for the caps I bought: (7) 470uF 63V Panasonic FC (Digikey # P10352-ND) (2) 220uF 35V Panasonic FC (Digikey # P10297-ND) (8) .22uF 50V Panasonic Polypropylenes (Digikey # P3224-ND) Note that if you buy 10 of the 470uF and the .22uF you will save money even though you only need 7 or 8 of them because of the qty discount. I believe the WIMAs are metallized polypropylene, right? I would assume the Panasonic Polyprop's might be better since they are not metallized. Pete said the 470uF would be fine, and I would probably suggest using larger than a 100uF at least for the output cap if you use low impedance headphones or you will lose some bass. Whether the Cerafines would make a big difference over Panasonic FC I couldn't say since I've never compared them. Upgrading the output cap to a Blackgate would be a good choice, but you can always do that later. If you are also ordering stuff from Mouser, you can save a little cash as mouser carries many of the parts that are listed on Pete's parts list from Digikey. Just do a search on the manufacturer's part number. Usually mouser is a little cheaper, but not always. As far as on-board upgrades there isn't much you can do besides change the caps and play with the different tubes and biasing. If you go off-board you can use nicer RCA jacks, potentiometer, power supply, and case. Hope this helps!

Thanks a bunch. I've decided to go for the Panasonic FCs (the largest I can fit on the board, since they're all so inexpensive). I've read a number of places that they actually measure better (and sound better) than the Cerafines. Since I want to order everything from as few stores as possible, I'm going to have to find a replacement for the Wimas now too. How are those panasonic polypros? What's the largest/best that will fit on the b oard? Should I bother socketing the tubes, and if so, do you have any reommended part #s from digikey or mouser? On an interesting note, I believe that this amp is the same design used in the upcoming Headroom Hothead. Anybody have any info on sound quality compared to a PIMETA? I really hope these mesh well with my DT880s.

 

[ITZBITZ]

Quote:

Originally posted by slindeman (8) .22uF 50V Panasonic Polypropylenes (Digikey # P3224-ND)

Thanks for the reminder! I use these caps for PPA bass boost and crossfeed circuits and they are very nice. I think I'll use this same part instead of the WIMA and since I make a weekly order from DigiKey anyway, that will be perfect.

 

[Voodoochile]

I also used those Panasonic film/foil caps. Pete Millett said that they would be at least as good as the original Wimas. FWIW.

It's a pretty cool amp, very nice for the relatively small outlay.