YAOB (yet another one-zero-two build)

[martin manning]

Another PT option: http://triodeelectronics.com/twredushsusi.html
You shouldn't need to elevate the filament string to get a quiet amp.

[aflynt]

Anybody tried the transformers from Hoffmanamps? He's got a Fender Twin power transformer that appears to be exactly the same as the old ones spec-wise:

HT 690VAC @310ma, 6.3V @6A filaments, 3x3 3/4" mounting centers...

I like dealing with him. When I ordered my wire for this build it was shipped out in less than 15 minutes!

-Aaron

[talbany]

It does both. Even in standby.

-Aaron

Alright

Check a few things..
Does the hum change slightly when changing V1 AX
In clean channel pull V2 does the hum get worse?
Does the hum go away when you pull the PI tube?

Tony

[aflynt]

Does the hum change slightly when changing V1 AX

I wont get a chance to try these until later on, but please forgive my ignorance... What is "AX?"

-Aaron

Edit: Figured it out. 12AX7.... Doh!

[talbany]

If it's the PT (Good chance) and you don't mind the extra weight and cost the export Twin/Showman PT from Mojo/Heybour is a bit better than the 120 only primary version..IMO
Remember 102 has an export..

Tony

[rogb]

Question for Tony:

I see this #102 uses the precision PS.
What are your thoughts on this compared to the original PS layout?

Reason I'm asking is I have one of these boards myself and I'm not sure whether to go with it as in this project or build one that follows the correct AG layout.

Great build by the way, I will be following you shortly with a 50w version

[talbany]

Question for Tony:

I see this #102 uses the precision PS.
What are your thoughts on this compared to the original PS layout?

Reason I'm asking is I have one of these boards myself and I'm not sure whether to go with it as in this project or build one that follows the correct AG layout.

Great build by the way, I will be following you shortly with a 50w version

You probably already know the answer but I'll say it anyway.
If your going after the true 102 tone and feel try to stay as close to the layout as possible,since it is the most accurate of all info so far posted on the www. of 102..
If you want to do a variation on the amp and like the PS power supply it will no doubt sound fine just a bit different..IMO..
FWIW..I personally do not use the PS supply because the caps I prefer are all Axial's (F&T,Spragues,TAD's)
Good Luck with the build!!

Tony

[rogb]

Thanks Tony, good answer

I used F&Ts in my last build (AB763 with modded normal channel) and I'm very
happy with that. I may build both boards and see how I get on with them.

I would really like to stick closely to #102, but I am a terrible modder and I can rarely leave anything stock.
Maybe 102 will be a first

[talbany]

I may build both boards and see how I get on with them.

Cool!!.. If you do (Please) report your opinion on each to the forum!!
BTW..The F&T's are the the closest (in materials used) to the old TVA's

Thanks Tony, good answer

I try to give these out every now and then..

Again Good luck with the build!!

Tony

[aflynt]

Does the hum change slightly when changing V1 AX

Not that I can tell.

In clean channel pull V2 does the hum get worse?

Not that I can tell.

Does the hum go away when you pull the PI tube?

Yes. Completely.

FWIW the hum is much worse on the overdrive channel.

-Aaron

[talbany]

Alright so we know the hum is coming from (more than likely) the filament supply from the pre amp side.. Since the problem started after you changed transformers we can rule out some kind of grounding or lead dress issues, (unless you changed some wiring on the pre amp side when you changed transformers or had a filter cap go bad).. I've had transformers that hum and vibrate on the chassis couple that hum into the pre amp filaments somehow and no matter what I tried could not get rid of it completely.. Sometimes you can really notice the hum get worse when you changed to different 12AX's sometimes you have to go through 5 or 6 before you can hear the change,sometimes not..So with this being said since your transformer is vibrating and this problem occurred right after the X-former change my next move would be to tack in another transformer and rule that out..I've seen 3 amps with transformers that vibrate do this..2 Heybours and an old Twin..

Good Luck

Tony

[aflynt]

Thanks so much, Tony! I'll try tacking in the old PT tonight and listen.

-Aaron

[aflynt]

I reinstalled the old Power Transformer (low B+ Quad Reverb) and discovered that the amp still hums in a similar way, just not as loud. Now I'm beginning to wonder if it always hummed but I just didn't notice it until the new higher B+ PT made it more obvious. Anyway... I put the new PT back in. For now I'll just see if I can live with the buzz.

Thanks for the help everyone!
-Aaron

[Structo]

Triode has the Twin Reverb PT for $86.54

http://triodeelectronics.com/twredushsusi.html

[aflynt]

Triode has the Twin Reverb PT for $86.54

http://triodeelectronics.com/twredushsusi.html

Thanks for the link! That's a very nice price. I'm not entirely certain that it IS the PT at this point, though given that it hums with both transformers.

-Aaron