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A Very Compact Hybrid Amp - Page 15

post #211 of 2213
Can anyone confirm the Pitch of C5P & C10P?

BoM lists 5mm pitch but pdf of the board measures 7.5mm.
post #212 of 2213
Quote:
Originally Posted by Forte View Post
Can anyone confirm the Pitch of C5P & C10P?
BoM lists 5mm pitch but pdf of the board measures 7.5mm.
Please take a look at your latest emails & if you don't find the info you need drop runeight or myself a PM....
post #213 of 2213
I have a couple of questions that may have been addressed already, but I can't recall for sure, so I'm sorry if I'm asking again.

The first is grounding the case - do we want the case to be tied to signal ground, or should it just be floating?

The second is transistor matching - are there any positions where hfe matching is going to improve performance?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I've got some tubes lined up for rolling once I get this built.

GE 5814
RCA 6189
Amprex 8416
CBS 7730
CBS 7318
post #214 of 2213
Thread Starter 
Transistor matching is not required as long as you use the "25" class BC327/337 and the "C" class BC550/560.

The case does not need to be grounded but the board's SG pad should be connected to the case.

Don't forget that the headphone jack's ground must float and be insulated from the case. It is connected to the OG pad on the board.
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #215 of 2213
guys what is the parts cost to build this amp? Do we have a BOM established?
post #216 of 2213
Quote:
Originally Posted by sachu View Post
guys what is the parts cost to build this amp? Do we have a BOM established?
Something like $130 USD complete w/case & adapter but search this thread for "shipping" for details... Should get some international cost feedback once all 10 prototypers are done. This for an amp w/unique & innovative things going on based on proven/tested designs. With a tube compatibility list as long as your arm, discrete rail + output buffers delivering class A into most headphones, no trimpot tube rolling, a single cap in the primary signal path of each channel, built-in e12 delay & offset protection in an amp that fits on your hand. And is impressing the heck out of the two prototypers that have them built

Here are my initial tube impressions from my meager tube collection (we'll need a tube thread):
  1. EH 12AU7 - Crisp, full range response. Bass & treble very present, almost akin to having the old "loudness" button pressed. Quite in your face but fun. Edit: Longer listening - A bit too hard/in-your-face
  2. Raytheon 12au7 - Like the EH but less so
  3. Raytheon CK5814a - From here down kinda mellow out w/o such noticeable bass & treble extension but lend "interesting" personality to music... May come back to them.
    Edit: Longer listening - I did come back to this & liking it!
  4. GE JAN 5963
  5. RCA 5815A
Note the list is almost an inverse of my preference for them in SOHA, again running them much "better" here. I've an Amperex 8416, Mullard 6922 & Sylvania 12BH7a on the way to try. Someday I will grab a BB 6dj8 too.

Quite satisfied w/this amp & I've not heard fancy-pants tubes in it yet
post #217 of 2213
Guys, We discussed the 24v Adapter from Mouser before XR-2440LED, and although Runeigth thought it might be a bit high at 1.6 A, isn't worthwhile including it on the BOM, since the price is decent, compared to sourcing elsewhere?

Although it's overkill, it would then be able to drive some of the higher powered tubes without a problem. I can see where there will be situations where people start trying the higher current tubes and then run into issues with overheating/failing transformers if they go with a lower rated unit.

I would also suggest that fuses be mandatory, if they are not already.
post #218 of 2213
I'm getting ahead of myself, but it occurred to me that two CTH's would fit very nicely into a 1455T2201, for a very small and interesting balanced amp.
post #219 of 2213
MrSlim are you one of the current prototypers? Don't recall...
WRT adapter although it never hurts to have more VA than you need we do not expect the amp to draw more than 0.8A -> 1.0A even with highest support tube heaters (12.6V/6.3V @ 600ma).
You make a good point though in how much headroom does a wallwart rated @ 1A have.. Think its customary for them to be rated at their max continuous draw, but some makers could cut corners. BTW, My 0.833A one gets barely/normally warm w/my 12.6-300ma heated tubes.

Think waitrob pinged the balanced idea a bit ago... If you are ever going to try it go for a 2.0A+ wallwart

Oh, up to runeight if that XR-2440LED (w/qty 0) appears on BoM (not a bad idea, just have the A/C jack size business to consider). Sachu - yes a BoM is around for proto PCBs.
post #220 of 2213
cfcubed, yes I Iam, although I was dragging my heels at getting my Mouser order in, while the BOM settled a bit.. I fired it off this morning. I still haven't received the board from Runeight yet, but I'm putting that down to the cross border issues.

If I decide to try the balanced route, I'd have to operate on my precious K601's... a scary thought
post #221 of 2213
Well, here's a teaser pic. Casing and wiring this afternoon. Finger's crossed!
LL
post #222 of 2213
Quote:
Originally Posted by wiatrob View Post
Well, here's a teaser pic. Casing and wiring this afternoon. Finger's crossed!
Great! Looks good to me...

Casing and wiring.. and LV reg HS I trust Geez maybe I should change my username to "Heatsink", "BrokenRecord" or something
post #223 of 2213
HScubed?
post #224 of 2213
Now it has one. Glad I got a spare 24V reg! It's pretty tight squueeze... Had to bend two fins to clear C4P, there's a few millimeters between the bottom of the sink and the TO-92s and it's way clear of the D3 and D1...
LL
post #225 of 2213
Wow you guys are amazing! I can't even think about building one of these, let alone designing it.
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