Yamaha Amps

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Daviedawg
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Re: Yamaha Amps

Unread postby Daviedawg » Mon Aug 31, 2015 9:08 pm

There have been recent reproductions like that one in your pic. The original ones are pretty sought after. And of course the Dominator circuit was the inspiration for Jim Marshall to produce the "Bluesbreaker" amp that Clapton used on the Beano album. And which lives on in the many "18 watt" builds like my own. So the Dommie is Royalty in the world of valve amps.

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Re: Yamaha Amps

Unread postby Buzzard » Sun Sep 06, 2015 12:48 pm

MxR wrote:Thank you for your help so far. Will report if I make some progress.


How is your TA-90 project coming on :?:

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Peter


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Re: Yamaha Amps

Unread postby MxR » Wed Sep 09, 2015 5:12 am

I finally got support from Yahama UK. They sent me a part of service manual for this model, so at least I now have a circuit diagram.

I am still waiting for new transistors. I couldn't get the exact ones, like in the schematics, instead I bought some with similiar specs. I'm also waiting for new 5W 0R5 resistors, which I will also change. I still have to measure ESR values of filter cap and speaker output cap.

There is however one thing that bothers me, in the circuit diagram B+ voltage is +90V. I have set the transformer's voltage to 220V (previously set at 240V). Even so, I still get only a little over +80V on B+. Could this be due to a bad filter cap?


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Re: Yamaha Amps

Unread postby Daviedawg » Wed Sep 09, 2015 5:09 pm

Try it back at 240v. It may be just what the transformer outputs. Did you measure the output at the trannie or after rectifier and filters? Take a few key readings under load and compare with the schematic.

I am not sure that the filter caps would be the problem but if in doubt new caps cannot be a bad thing.

Dd


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SF500 Sunburst three colour Aug 1978
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SC400 red transparent 1982
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Re: Yamaha Amps

Unread postby MxR » Mon Sep 14, 2015 7:11 pm

I measured filtered DC (so between the +Vdc contact of the filter cap and GND). When I had the transformer set at 240VAC, B+ voltage was around 78V, under no load. When the transformer windings were set at 220VAC, B+ under no load is a little over 80V. The transformer's label matches the model number in the schematics, so the transformer is original.


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Re: Yamaha Amps

Unread postby JereFuzz » Sat Dec 26, 2015 1:56 am

I bought a G50-112 basically on looks alone. Those old Yamaha grill clothes are amazing. Luckily, the G50-112 still worked, including the reverb! It has some crackles and volume drops so I took it to a shop to get it repaired. Mine looks to be in the same condition as this one:

Image

The sound is quite nice but the distortion is a bit limited. I wonder why more amp makers don't put more thought into the patterns of the grill cloth? Anyway, I'd like to see Yamaha put new amps into production with that old late 70s/early 80s style.

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Re: Yamaha Amps

Unread postby JereFuzz » Sat Dec 26, 2015 2:03 am

Actually, mine's in better shape than that one ...


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Re: Yamaha Amps

Unread postby JereFuzz » Sat Dec 26, 2015 2:04 am

Got it for $150 ...


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Re: Yamaha Amps

Unread postby Buzzard » Sat Dec 26, 2015 1:07 pm

JereFuzz wrote:I bought a G50-112 basically on looks alone.
The sound is quite nice but the distortion is a bit limited. Regards ...


Hi JereFuzz , Welcome to the Yamaha Forums. :D

Most of the amps in the "G" series have a fairly weak distortion, more like an overdrive.
If you use a guitar with high output humbuckers, you'll have distortion, but no metal.
The "G" amps work well with pedals, and they are generally quite loud.

Best Regards
Peter


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Re: Yamaha Amps

Unread postby JereFuzz » Sat Dec 26, 2015 4:40 pm

Buzzard wrote:
JereFuzz wrote:I bought a G50-112 basically on looks alone.
The sound is quite nice but the distortion is a bit limited. Regards ...


Hi JereFuzz , Welcome to the Yamaha Forums. :D

Most of the amps in the "G" series have a fairly weak distortion, more like an overdrive.
If you use a guitar with high output humbuckers, you'll have distortion, but no metal.
The "G" amps work well with pedals, and they are generally quite loud.

Best Regards
Peter


Thanks for the info. With Yamaha's renewed commitment to guitars (Revstar) hopefully this translate to a new commitment to amps. I'm in the market for a Revstar and I would be in the market for a new Yamaha amp if they can nail down the aesthetic.

Regards ...


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Re: Yamaha Amps

Unread postby Buzzard » Sun Dec 27, 2015 12:25 am

JereFuzz wrote: I'm in the market for a Revstar and I would be in the market for a new Yamaha amp if they can nail down the aesthetic.

Regards ...


If you're gigging, the THR-100 models might be a good choice for you, or maybe the DG models.
If you're mostly playing at home and for practice, the THR-10 models are brilliant. ((i))

Regards
Peter


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Yamaha J-110L (115L) bass cabinet

Unread postby Buzzard » Sun Feb 14, 2016 5:24 pm

My bass stack just grew up ((i)) ....... TALL as a man. :D

From this: .......................................................................................................................... to this: ((i))
Image Image

:?: Did I reallly need to get a bass double stack :?: ........ NOPE , but the price was right, and I just couldn't resist it.
I rarely use this bass amp setup, since it's definitely NOT neighbor friendly, still, way too cool to pass up.

These 115 cabinets are great for guitar too, giving more "bottom end" to your guitar.
I tried using it with a Yamaha G-100 212 II and even with different guitar amp heads: G-100 , G-100 II , DG-130Ha, ALL sounds good.
Image Image

Speaker is a single (Yamaha JA-38020) 15" , 120watt , 8ohm unit, in a bass reflex cabinet.
Image

Regards
Peter


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Re: Yamaha Amps

Unread postby jeff-carolina » Sun Feb 14, 2016 6:39 pm

Congrats on your new acquisition!!! Certainly looks impressive. Love that Weddington


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Re: Yamaha Amps

Unread postby Buzzard » Sun Feb 14, 2016 7:12 pm

jeff-carolina wrote:Congrats on your new acquisition!!! Certainly looks impressive. Love that Weddington


Thanks Jeff.

The Weddington is a good choice for testing amps, it has so many sounds due to the pickup settings, giving a wide range of tone.

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Peter


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Sometimes you gotta compromise ..........

Unread postby Buzzard » Mon Feb 15, 2016 10:19 pm

The amps that are not currently in use must be stored somehow. :roll:

I really could use a LARGE room with all amps set up ready to play.

The compromise is to SHARE space for my gear. (Y)

Image

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Peter


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