Genz Benz Streamliner Fault

[Fretless Fiend]

AnyValve techies know what this could be?? I have a Genz Benz 900 Streamliner Head which has been my go-to Amp for the last 5 years. Prior to a gig yesterday the  first one after  a long lay off I noticed that the active mid frequency filter does not appear to be working properly and I I am sometimes getting  a mild overdrive distortion when I hit the strings hard. I am familiar the operation of the gain and drive an eq functions and know that the front end isnt working as well as it used to. Could this be a problem with one of the valves going a bit soft? They are around 3 years old and have had moderate usage up until March 2020 and then only used sporadically at low volumes up until yesterday.

 

Thanks

Andy

 

 

[Bigguy2017]

First try re-seating the valves.

[Gareth Hughes]

The designer of the Streamliner is a regular here - AgedHorse/Andy. He’s been really helpful to me in the past with any Genz Benz issues/queries. Drop him a line, he’ll be the perfect guy to point you in the right direction.

[Silky999]

I have the same amp. Try swapping the tubes around and see if the problem moves. The top is very easy to take off with an Allen key but makes sure you let the valves cool down and unplug the power between changes. If the problem moves then you can identify which valve. From left to right if looking at the front…1st is gain, then bass and treble, 3rd is mids. Sometimes just pulling a valve out and re-seating it is enough to get it working again. 
I think the standard valves are a JJ ECC83S and 2 Ruby ECC83 in that order. 
Aged Horse is the man with all the knowledge of that amp and gave me advice about changing the broken blue leds.

Edited August 24, 2021 by Silky999

[Downunderwonder]

First order of trouble shooting is try another amp keeping everything else same.

[Fretless Fiend]

Thanks for the sound advice guys. I swapped the two eq valves around and the problem disappeared completely. Swapped them back and the problem didn't come back. I think reseating them as suggested, plus some very fine emery on the pins did the trick.

 

[Fretless Fiend]

Hi It's me again, having got my initial problem sorted I have noticed that when I turn the gain control past 12.0clock there seems to be little difference in the volume and doesn't make any difference to the output level or tone.  Volume control increases as expected. Have tried several valves in the V1 slot and they behave exactly the same. Is this normal? Playing as I do, with a clean sound and rarely over-driving I have not noticed this before as the gain is normally set between 9-10. I have a GB shuttle 6 as well and this winds its gain all the way up to max.... which is what I thought I would expect on the Streamliner.

[Silky999]

This is what the manual states;
 

 

GAIN SWITCH – This switch sets the gain sensitivity of the preamp gain stages. With the switch set to the IN

position and the Amber indicator LED illuminated, the gain stages are set to a higher sensitivity, driving the preamp

gain stages harder, producing more harmonic content and overdrive. The degree of overdrive will depend upon the

output level of your bass guitar pick-ups and preamp as well as your playing style. This switch should be used in

conjunction with the Gain control for setting the overall gain structure of the preamp. This switch can also be used as

an Active/Passive switch. The lower gain position is more suitable for high output level active basses and a cleaner

tone.

GAIN CONTROL – This control sets the input gain of the 12AX7 TUBE preamp. The volume of the signal is then

controlled by the Tube Preamp Volume control and also the Master Volume control. Note that overdriving the input

tube gain stage may be a desirable tonal characteristic of your playing style. This control, in conjunction with the

Gain switch, Preamp and Master Volume controls, allows you to set the amount of tube overdrive or clean tone your

amp produces.

PREAMP VOLUME CONTROL – This control sets the volume (and make-up gain) of the preamp after the Input

and EQ stages but before the Effects Send jack. Use this control in conjunction with the Gain and Master Volume

controls to achieve the necessary gain structure for your playing and music style

 

so I think yours is working as it should….