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A Very Compact Hybrid Amp - Page 80

post #1186 of 2203
5/8/09 at 9:14am
Quote:
Originally Posted by cfcubed View Post
[I][*]This reminded me I've non-BoM C4 caps in BOTH my builds. And I know that a couple others that mentioned hum did also (TimJo). So non-BoM couplers could be involved. [*]I shielded my input runs, but larger C4s added between 2 & 4 inches of unshielded wire to the input stage.[*]wiatrob - Don't see you doing experiments if you don't hear the problem[/LIST]
I am using the wimas Bill provides, so non-BOM, but no long leads.

There did seem to be a number of builders who heard noise with the 6n1p. It may be useful to mention what headphone is used to test. For instance, I don't hear it with 32ohm px-100, and hear it somewhat with 32ohm RE2, but do hear it most clearly with 50ohm SA6, so I think sensitivity and the nature of iems and maybe even armatures bring it out.
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post #1187 of 2203
5/8/09 at 10:16am
Quote:
Originally Posted by HeadphoneAddict View Post
I NEVER heard any hum with the loaner CTH from wiatrob and Mullard short plate, even with very sensitive IEM.
And from looking at Sherwood's review, he heard a slight hum on my Proto. I need to collect that amp when Blutarsky is done with it and do a side by side.

That's the proof build an it actually has socketed coupling caps (Wimas in both my builds) so it has 'longer' leads.
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post #1188 of 2203
5/8/09 at 11:14am
I plan to conduct the tests as I suggested them within the next week, if y'all can wait that long

I'll be doing this on my 2nd CTH w/more room + bottom mounted heater reg so it will be easier to fiddle. Again, disabling the switcher entirely & trying 6V batt heater supply... If noise/hum disappears will lower switcher Vin to < 24V w/resistor & see if that helps.

I plan to pull the Mundorf S+Os & replace w/Sonicap Gen Is and will try to shield their leads (& ground the shields). We have a lot going on in a small space.

OK enough for me for now, need "Less posting, moar building" as Nate posted elsewhere
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post #1189 of 2203
5/8/09 at 12:50pm
Quote:
Originally Posted by cfcubed View Post
But even the minority hearing this very faint noise/hum between tracks seem to report they really like the amp... And for many it has become their primary amp (often displacing other DIY amps.)
Absolutely! Still the most enjoyable and engaging amp I have heard, my other amps are gathering dust.

Quote:
Originally Posted by cfcubed View Post
I plan to conduct the tests as I suggested them within the next week, if y'all can wait that long

I plan to pull the Mundorf S+Os & replace w/Sonicap Gen Is and will try to shield their leads (& ground the shields).
Look forward to hearing the results of your tests, especially the shielding of the cap leads.
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post #1190 of 2203
5/8/09 at 12:50pm
Quote:
Originally Posted by keyid View Post
Nice Diagram
Yeah, it's awesome and very detailed isn't it? Thanks to Ric Lee for making it

Quote:
Originally Posted by smeggy View Post
I feel left out now because I don't have any hum
smeggy, I recall you have cans that come with hookup wires that can be connected directly to your A/V receiver's speaker outs ...that or unless sachu uses proprietary components when he builds them
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post #1191 of 2203
5/8/09 at 12:51pm
Quote:
Originally Posted by Forte View Post
Absolutely! Still the most enjoyable and engaging amp I have heard, my other amps are gathering dust.
Its a good amp, and for the size its very good. But the bijou is in another class, both in sq and COST!
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post #1192 of 2203
5/8/09 at 1:40pm
Good to know. I'll be joining the Bijou crowd soon. I finally got motivated to get off my ass and finish it, I finished air wiring my tube sockets last night. 2 years in the making, sitting in a case without wire....I absolutely hate wiring, panel work, etc.
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post #1193 of 2203
5/8/09 at 3:35pm
Quote:
Originally Posted by cfcubed View Post
IOW, think this issue is a very minor one affecting a minority of CTH builds/listeners. E.g. in my case, its sooo minor I'm not motivated to open the case to experiment
This has been my feeling as well. I'd rather keep listening to it than take the time to fiddle with it...

But I was wondering about the non-bom interstage cap theory. The way I mounted the VitQ's, I suppose I could be picking something up via the leads.
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post #1194 of 2203
5/8/09 at 3:50pm
Quote:
Originally Posted by wiatrob View Post
And from looking at Sherwood's review, he heard a slight hum on my Proto. I need to collect that amp when Blutarsky is done with it and do a side by side.

That's the proof build an it actually has socketed coupling caps (Wimas in both my builds) so it has 'longer' leads.
Are they two different amps? And if not different amps, could the difference be the tubes we used? I was too lazy to try anything but my Mullards.
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post #1195 of 2203
5/8/09 at 4:00pm
Quote:
Originally Posted by wiatrob View Post
And from looking at Sherwood's review, he heard a slight hum on my Proto. I need to collect that amp when Blutarsky is done with it and do a side by side.

That's the proof build an it actually has socketed coupling caps (Wimas in both my builds) so it has 'longer' leads.
The one I built for Smeggy actually has sockets for the coupling caps. However I did install BOM caps on his amp.
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post #1196 of 2203
5/8/09 at 11:38pm
Quote:
Originally Posted by HeadphoneAddict View Post
Are they two different amps? And if not different amps, could the difference be the tubes we used? I was too lazy to try anything but my Mullards.
One is built on the Proto PCB and one on the production PCB. I did talk to Sherwood this afternoon. The noise he heard was without music playing, with volume cranked. I hear noise on ALL tube amps in that scenario.

There is virtually NO difference between the two PCBS. BUT - the proof build you had does have higher amperage inductors - it's rated to run the 6H30 - I think 1 and 1.25 Amps. I sent a set to Holland, but don't know if he's tried them.

I'm about to curl up with mine and this Siemens ECC82 Chrome Plate...
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post #1197 of 2203
5/9/09 at 12:09am
Quote:
Originally Posted by adamus View Post
Its a good amp, and for the size its very good. But the bijou is in another class, both in sq and COST!
Glad to hear that. I have a set of Bijou boards from the original group buy that I can finally start to build having found a budget chassis at last. Won't be as desktop friendly though given its size.
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post #1198 of 2203
5/9/09 at 12:12am
Quote:
Originally Posted by wiatrob View Post
One is built on the Proto PCB and one on the production PCB. I did talk to Sherwood this afternoon. The noise he heard was without music playing, with volume cranked. I hear noise on ALL tube amps in that scenario.

There is virtually NO difference between the two PCBS. BUT - the proof build you had does have higher amperage inductors - it's rated to run the 6H30 - I think 1 and 1.25 Amps. I sent a set to Holland, but don't know if he's tried them.

I'm about to curl up with mine and this Siemens ECC82 Chrome Plate...
I have a new Siemens E82CC (according to the box) still here in the shrinkwrap.
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post #1199 of 2203
5/9/09 at 12:24am
Quote:
Originally Posted by HeadphoneAddict View Post
I have a new Siemens E82CC (according to the box) still here in the shrinkwrap.
Give you 5$ for it
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post #1200 of 2203
5/9/09 at 2:54am
im really enjoying my Siemens 5814A triple mica just got them the other day
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