Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Zebop on August 21, 2021, 05:17:11 pm

Title: Seymour Duncan 100 convertible
Post by: Zebop on August 21, 2021, 05:17:11 pm

Hello,

I hope somebody can help me out. I’m trying to replace the tubes to the
Seymour Duncan 100 convertible. However, when I went to Amplified Parts website they give you several choices of tubes. Can anybody tell which ones come close to the stock tubes the amp came with. Or if you don’t telling me what are differences in these tubes. It will greatly be appreciated.
Thanks for your help
Danilo

Title: Re: Seymour Duncan convertible
Post by: sluckey on August 21, 2021, 07:26:40 pm

Call plexi50. He's in your area.

Title: Re: Seymour Duncan 100 convertible
Post by: acheld on August 21, 2021, 09:42:26 pm

Hi there.  This is probably the wrong location for your post -- one of our moderators will likely move it.

Couple of questions for you:   Is there a problem with your amp?  Is it operating well, or are you trying to correct a problem?  Or are you just trying to do maintenance?

I'm not personally well acquainted with this amp, but the schematic we have shows a of quad EL-34 tubes, 1 12AX7, a pair of 12AU7, and a 5U4 rectifier tube.  Is this correct?  Amplified Parts is saying that you need 6 12AX7 tubes, which seems unlikely to me -- but I may be looking at the wrong schematic.   How many tubes are actually in your amp?

I looked at the brands Amplified Parts is offering, and I think there is not much difference between them.  This is likely to be a controversial statement, to say the least.   I personally prefer Sovtek, Mullard Reissue, and TAD as brands.  BUT, are they really better than anything else?  Probably not.   I generally stay away from Chinese tubes, but I am sure there some quality built tubes from there as well.

I normally deal with Antique Electronic Supply, which I think is the same company as Amplified Parts, and have had great luck with their service.   When I get a bum part, a phone call is all it takes to get a new one shipped pronto.  That is the key for you.

If there is an actual problem with your amp, though, just throwing a bunch of new tubes may or may not solve the problem.

Title: Re: Seymour Duncan 100 convertible
Post by: John G on August 22, 2021, 02:22:21 am

Hi,
I have seen at least TWO versions of this amp.The power amp section does differ so I suggest that you find the two schemos and compare differences.
Dougs schematic section might have them.
Getting the right set of tubes will make all the difference in how well the amp performs.
John

Title: Re: Seymour Duncan 100 convertible
Post by: Zebop on August 23, 2021, 03:32:32 pm

Thanks for the advice. The original tubes are in the amp, over twenty years. When I turn the on strange sounds are coming out. So I figured it’s time to invest  on new tubes.