SET Asylum

Single Ended Triodes (SETs), the ultimate tube lovers dream.

Return to SET Asylum

Message Sort: Post Order or Asylum Reverse Threaded

300/76/6sn7 Hogan amp - Repaired? Cap questions

76.21.130.64
Posted on May 28, 2020 at 04:59:37
jackpollard
Audiophile

Posts: 15
Location: NE US
Joined: September 5, 2010



Hello all;

So I posted about my Hogan amp having distortion issues and getting it repaired. Turned out a relative of a friend owned an electronic repair company for many years and was doing home repairs. He initially changed the resisters, no fix. Then put the meter on the cap's and they were swinging all over the place. The Hogan has 6 caps, they all seemed to be Illinois Capacitor (IC) 450V 100uF caps. He swapped them all out. I posted a pic of the before.

Now I can't tell if it's my ears, but for some reason the amp just does not sound as liquid as it used to. Again it might just be me. Do caps have that big of an impact on the sound? Should I redo the caps?

Thanks in advance

 

Hide full thread outline!
    ...
RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on May 29, 2020 at 07:03:39
rogerh113
Audiophile

Posts: 507
Location: San Francisco South Bay
Joined: October 20, 2014
 I am no expert, but I do think caps make a big difference. If you do a search, you will find a lot of cap shoot-off discussions and comparisons. Like in all things, often the 'worst' component will determine sound quality, and that might be happening to you. I was very careful about cap selection, as well as all component selections, when I built my amp.

Component placement, wire routing, and work quality can also make a difference. If you have a picture of the inside before the work was done, that would be useful to see.

 

Good news, posted on May 29, 2020 at 08:38:42
RayP
Audiophile

Posts: 727
Location: Maryland
Joined: June 30, 2005
 I am pleased to see that you got the problem fixed. Happy listening.

ray

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on May 29, 2020 at 09:35:51
jackpollard
Audiophile

Posts: 15
Location: NE US
Joined: September 5, 2010
 Thanks for both your responses!

Ray; I so thank you for your suggestions and help!

The picture I posted is the before. The after is mainly the same.

They used the same brand caps, the main difference is the Illinois Capacitor (IC) 450V 100uF were replaces with Illinois Capacitor (IC) 500V 47uF caps.

DO you think that would constitute a major change?

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on May 29, 2020 at 11:41:43
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since: September 9, 2000
 What caps did you use?

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on May 29, 2020 at 12:32:44
jackpollard
Audiophile

Posts: 15
Location: NE US
Joined: September 5, 2010
 They were Illinois Capacitor (IC) 500V 47uF caps. The old ones were 450V 100uF.

I know the volts should not be lower than what was replaced, but should the uF difference matter?

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on May 31, 2020 at 08:31:34
WntrMute2
Audiophile

Posts: 782
Location: Detroit
Joined: September 16, 2002
 I don't know if you have solved your issue yet but you choose caps that are the wrong value and are now wondering if that could effect the sound? That will effect the sound far more than the manufacturer will IMHO. PReplace with the correct values and update us

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on May 31, 2020 at 10:52:21
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since: September 9, 2000
 Yes. I thought it was odd. A higher voltage is no big deal, but a much different value can make a big difference.

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on May 31, 2020 at 15:25:06
jackpollard
Audiophile

Posts: 15
Location: NE US
Joined: September 5, 2010
 I thought he did use the same caps, when he pulled them out he said "Great I have 6". It was not until I got home I realized they were different.

I did order 6 of the correct value caps, it would have bothered me until I did.

Now I have to either hone my soldering/desoldering skills or find someone again. But that's a whole other post.

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on June 1, 2020 at 07:36:49
Cpwill
Audiophile

Posts: 1096
Location: DC
Joined: December 22, 2003
Contributor
  Since: October 24, 2008
 From the picture in your original post, it looks like a fairly simple solder job (easily accessible, not a lot of other leads on the tags, etc.), but you might want to have some copper wick or a solder sucker. From the locations, it would guess the lower capacitance has lowered your B8 accounting for the reduced SQ.

Where in the NE are you?

Good luck and stay safe.


"Anyone who understands jazz knows that you can't understand it. It's too complicated. That's what's so simple about it." - Yogi Berra.

Cpwill

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on June 1, 2020 at 10:52:17
jackpollard
Audiophile

Posts: 15
Location: NE US
Joined: September 5, 2010
 Thank you for the response, I might, stressing the "might" attempt it myself.

If you don't mind me asking, what did you mean by; "lower capacitance has lowered your B8 accounting."

My very novice understanding is the microfarad difference is in the amount of capacitance that's available for use. So the new caps have roughly 1/2 the amount as the old.

I'm in Maryland.

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on June 1, 2020 at 11:19:44
Cpwill
Audiophile

Posts: 1096
Location: DC
Joined: December 22, 2003
Contributor
  Since: October 24, 2008
 My apologies, it's a typo. I meant to type B+. The 4 IC Caps in the picture appear to be in the power supply filter. As they store energy, cutting the value in half will reduce the B+ voltage, probably by a lot. B+ feeds the output transformer and tube anodes. A difference of 10-15% +/- won't change SQ much, but more than that changes the whole operating points of the tube, increasing distortion or worse.

I am in DC. If you would like help once the caps arrive, send me an email. Masks required.


"Anyone who understands jazz knows that you can't understand it. It's too complicated. That's what's so simple about it." - Yogi Berra.

Cpwill

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on June 1, 2020 at 16:43:16
Paul Joppa
Industry Professional

Posts: 7295
Location: Seattle, WA
Joined: April 23, 2001
 Assuming the caps are the power supply filters, it won't change B+ by much. It will however increase ripple (hum), which may or may not be audible.

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on June 2, 2020 at 05:55:41
jackpollard
Audiophile

Posts: 15
Location: NE US
Joined: September 5, 2010
 Thanks for explaining that, makes sense.

I also appreciate your offer, I have to say the people on this forum have always been the nicest I've ever met! While I wait for the cap's I have some older more or less junk electronics that I might work on to hone my skills a bit. I will certainly let you know and again thank you.

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on June 2, 2020 at 06:05:06
Cpwill
Audiophile

Posts: 1096
Location: DC
Joined: December 22, 2003
Contributor
  Since: October 24, 2008
 I stand corrected.


"Anyone who understands jazz knows that you can't understand it. It's too complicated. That's what's so simple about it." - Yogi Berra.

Cpwill

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on June 2, 2020 at 13:25:30
91derlust
Audiophile

Posts: 1101
Joined: December 25, 2014
 Will it affect the output impedance of the supply? Could that affect sound quality?

I suspect the PSU in the Hogan amp was not "engineered" so maybe it doesn't matter. 47uF does seem a bit low value to supply a low rp triode, if that is what it is doing.


"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

RE: 300/76/6sn7 Hogan amp - Repaired? Cap questions, posted on June 2, 2020 at 13:39:47
Paul Joppa
Industry Professional

Posts: 7295
Location: Seattle, WA
Joined: April 23, 2001
 Good call.

Yes, the output signal current flows through the power supply, mostly through the last filter capacitor, so that would have some effect. At 20Hz the reactance of 47uF is 160 ohms - not insignificant relative to the 3000 or so output transformer primary impedance.

 

Thanks Paul. I've learned a lot from your posts. Nt., posted on June 3, 2020 at 03:00:27
91derlust
Audiophile

Posts: 1101
Joined: December 25, 2014
 .
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

Page processed in 0.033 seconds.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]