Traynor YBA-1 sounds crappy

[Cloutier]

Hi,

I have my friend's Traynor YBA-1 that he uses for bass. It sounds really crappy, no headroom, distorting with volume as low as 1. A sound I would describe as "farty", for the lack of a better word. Same with a guitar plugged instead.

I have the schematic attached. Sorry for the poor quality, but that the only one I could find that corresponded to what's inside the amp. The only difference is the one I have has a 470K resistor between V2A grid and ground. Anyone knows what's the use, compared to none as per the schematic?

It came with GT valves, which where replaced with Electro Harmonix 6CA7EH. The problem worsened.

I checked every resistors and they are good. The voltages and resistances on the power transformer are good, no shorts or opens. Same for the primary side of OT. However, I measure only 1.8R between the secondary leads, that's 0.6 if I subtract the internal 1.2R of my DMM. I unsoldered them just to make sure I wasn't getting a false reading. So far that's the only thing I can see. Is this reading normal?

Any ideas appreciated.

Thanks.

[Leo_Gnardo]

Same for the primary side of OT. However, I measure only 1.8R between the secondary leads, that's 0.6 if I subtract the internal 1.2R of my DMM. I unsoldered them just to make sure I wasn't getting a false reading. So far that's the only thing I can see. Is this reading normal?

Yes, and the DC resistance of the OT's secondary winding has little to do with the amp's health.

Before we go blaming the amp for everything, have we tried different/better speakers with this amp? Also test with a known good instrument & cable, no effects in the way?

Way back when, I had a similar Traynor, and the first day I played it through a pair of ElectroVoice 15's "WOW Why haven't I done this before?" Big improvement over what cheap 15's Traynor had installed.

[loudthud]

Take Voltage readings and compare to the numbers on the schematic.

[Cloutier]

Yes, and the DC resistance of the OT's secondary winding has little to do with the amp's health.

Before we go blaming the amp for everything, have we tried different/better speakers with this amp? Also test with a known good instrument & cable, no effects in the way?

Way back when, I had a similar Traynor, and the first day I played it through a pair of ElectroVoice 15's "WOW Why haven't I done this before?" Big improvement over what cheap 15's Traynor had installed.

Thanks for the replies.

The speakers are Peavey sp15-825. They are working good. I plugged the cab to my fender hot rod deluxe and it worked fine. Same crappy sound with two different perfectly working basses and two different perfectly working guitars. Decent cable, 10 ft.

Plate voltages where ok.

Thanks again.

[Cloutier]

Anything else?

[Mick Bailey]

Check the screen voltages at the tube sockets. Also check the amp is biased correctly.

Ignoring the headroom/distortion, is there any volume there?