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31
Q & A / Re: Original Model T questions.
« Last post by _peter on May 24, 2018, 01:36:48 am »
Don't worry, that's just the way they build amps back in the days.
I can't make out any component in the picture that has been touched.
Maybe, after all these years, the amp might need a cap job.

Peter
32
Q & A / 76 Red Knob Concert Lead Output Transistors
« Last post by bigmufffuzzwizz on May 23, 2018, 09:00:33 pm »
I’ve got a red concert lead on my bench.  I’ve come to the conclusion from testing that Q3  is bad (reading voltage from collector to emitter). This unit has 22-3155 7613 transistors (not available) instead of the still available 2n3055 listed on the scheme. Are these interchangeable? Considering the scheme should I replace all 5 Q’s with 2n3055 like the original scheme? Can I just replace one or need they be changed in pairs similar to tubes?
33
Q & A / Re: Inexpensive speaker repair suggestion.
« Last post by GrannyGremlin on May 23, 2018, 12:03:25 pm »
Nice clean tear - easy to fix.

Don't use epoxy - too heavy.  Rubber/contact cement only if it's a poly cone vs paper.  For a paper cone like this one use regular white/school glue.  Water it down a bit so it doesn't go on thicker than necessary, dries slower, and paints on with a brush easier (though sometimes I just finger it on).  Alternatives include Wood Glue and  Modge Podge (in both cases def water down) - both being water based as well and very similar.

Paper towel is a bit thick - I use toilet paper (if thick/multiply, use a single ply).  Layer of glue on both front and back, line up the tear, stick on TP patch on rear only ( don't want to see that from the front), and then paint over the patch with another layer of glue (watering it down as mentioned also helps is not rip the TP when you top coat). Optionally another coat on the front as well if you're worried it's not strong enough.  Be conservative with the glue - you can always add another coat later.

Basically you don't want to add significant weight in an unbalanced way. That can be bad.  Adding weight in a balanced way (e.g. paint the entire cone with watered down glue/mod podge) is a common mod in DIY HiFi circles for cheap drive units when you want to lower the resonance/bass response and don't mind risking the loss of a bit of high end (cuz there's a tweeter for that anyway).  I've repaired many a low power vintage alnico this way (reconing is not worth it - costs more than replacing the speaker).  After a few you even learn to make them not so damn ugly.

34
Q & A / Re: Inexpensive speaker repair suggestion.
« Last post by bigobassman on May 22, 2018, 06:31:30 pm »
I've repaired several splits like you have.  You need a sheet of paper towel and some flexible rubber glue/cement that is applied with a brush.  Cut a strip of paper towel a little larger than the tear.  Apply a layer of glue around the tear and then lay the paper towel section as smooth as possible over it.  Then put a layer of glue over the top of the towel extending out on the cone some.  If possible, do the back side as well.  Works great!   :-)
35
Q & A / Re: Original Model T questions.
« Last post by RacerX on May 22, 2018, 08:19:58 am »
Hi _peter, Thanks for confirming it is stock. In the 80’s I bought a kit to modify my guitar for “killer tone” from the back of a guitar magazine. It consisted of some resistors, capacitors and other things that we’re to be soldered between the pots, pick-ups and switch. When it was completed it sort of looked like the inside of this amp. It just had this homemade look with electical parts soldered in places and that is what the inside of this Model T reminded me of.
36
Q & A / Re: Inexpensive speaker repair suggestion.
« Last post by eddiemac on May 22, 2018, 06:54:41 am »
I would try a light application of epoxy glue, to the crack only  - just enough so it stays solidly together.
37
Q & A / Re: Original Model T questions.
« Last post by _peter on May 22, 2018, 03:56:40 am »
Hi,

it's a first generation and it looks stock. Why do you think it has been modified?

Best,
Peter
38
Q & A / Re: Inexpensive speaker repair suggestion.
« Last post by RacerX on May 21, 2018, 07:58:17 pm »
Sorry, pictures from iPhone load as incompatible.
39
Q & A / Inexpensive speaker repair suggestion.
« Last post by RacerX on May 21, 2018, 07:54:33 pm »
Hello,  I have a Sunn Beta 402 that I have let set for a long time. I went to use it and noticed all four speakers have identical cracks. Only one crack per speaker, and all are the same. I was pressing on the cone to get the separation seen in the picture. The material actually closes up tight without any pressure on it. I need inexpensive repair so someone can use it long enough to try my amp or I can make a short video to demastrate it. I understand it would be best to replace or recone them but it looks like the value of a Beta 402 would only be worth what it would cost to properly repair it, or even less with shipping’s . I was thinking of using some fingernail polish or latex caulking?  I also read in a post where a guy said to lightly spray the cones with lacquer to refresh them. So I was wondering if maybe there is a material like felt, I could embed in the crack and use some lacquer as an adhesive. Any advice would be appreciated. Thank you in advance.
40
Q & A / Re: Sunn Sorado Coupling Caps
« Last post by Soundmasterg on May 20, 2018, 11:35:32 am »
Its a subtle thing, but the effect is clearly there. Its up to taste...use whichever one you like better.

Greg
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