Genz Benz Shuttle 9.0 troubles!

[morebasstimes10]

I just bought this amp used because my GB Shuttle 6.0 was not quite cutting it for larger gigs. I tried it out with my Epifani UL 410 (4 ohm) and it wasn't as loud as the 6.0 combo with it's single 12" speaker. Took it in to my repair guy and got this:

Hi Jack. I tested your Shuttle 9.0 and this is what I found.
1)Fan was on at power up. Tested with dummy load and Fan speed increased as power output increase with slight delay.
2) at idle output (measured with scope) a high frequency oscillation on o approximately 400mv peak to peak. Could not be detected when output connected to speakers.
3)Power output test with 100 Hz and1Khz input.
Output measured 500Wrms into 4 ohm dummy load.
Don't know if this normal or not. Do not have schematics for this amp.

The preamp tube tested fine and without a schematic for my tech I am at a dead end. Any advice (besides throwing it off the nearest bridge) would be greatly appreciated!
Thank you my bass buddies!

 

[rapidfirerob]

I just bought this amp used because my GB Shuttle 6.0 was not quite cutting it for larger gigs. I tried it out with my Epifani UL 410 (4 ohm) and it wasn't as loud as the 6.0 combo with it's single 12" speaker. Took it in to my repair guy and got this:

Hi Jack. I tested your Shuttle 9.0 and this is what I found.
1)Fan was on at power up. Tested with dummy load and Fan speed increased as power output increase with slight delay.
2) at idle output (measured with scope) a high frequency oscillation on o approximately 400mv peak to peak. Could not be detected when output connected to speakers.
3)Power output test with 100 Hz and1Khz input.
Output measured 500Wrms into 4 ohm dummy load.
Don't know if this normal or not. Do not have schematics for this amp.

The preamp tube tested fine and without a schematic for my tech I am at a dead end. Any advice (besides throwing it off the nearest bridge) would be greatly appreciated!
Thank you my bass buddies!

AgedHorse will chime in. He designed the amp and repairs them. He's here on TB.

 

[basscooker]

@agedhorse has a quick and inexpensive service. Recommended.

 

[Wasnex]

I just bought this amp used because my GB Shuttle 6.0 was not quite cutting it for larger gigs. I tried it out with my Epifani UL 410 (4 ohm) and it wasn't as loud as the 6.0 combo with it's single 12" speaker. Took it in to my repair guy and got this:

Hi Jack. I tested your Shuttle 9.0 and this is what I found.
1)Fan was on at power up. Tested with dummy load and Fan speed increased as power output increase with slight delay.
2) at idle output (measured with scope) a high frequency oscillation on o approximately 400mv peak to peak. Could not be detected when output connected to speakers.
3)Power output test with 100 Hz and1Khz input.
Output measured 500Wrms into 4 ohm dummy load.
Don't know if this normal or not. Do not have schematics for this amp.

The preamp tube tested fine and without a schematic for my tech I am at a dead end. Any advice (besides throwing it off the nearest bridge) would be greatly appreciated!
Thank you my bass buddies!

Here are the specs:

Shuttle 9.0 900W Lightweight Bass Amp Head Specifications:

• Power Output 500W/900 W, 8 Ohm/4 Ohm

Shuttle 6.0 600 Watt Lightweight Bass Amp Specifications:

• Power: 375W/8 ohms; 600W/4 ohms.

Regarding the HF osciallation.

Class D works on pulse width modulation (PWM). The square wave is a way higher frequency than the audio. The Low Filter blocks most of the PWM square wave. No idea if 400mV is acceptable or not.

 

[agedhorse]

The typical repair tech does not have the necessary knowledge or skill level to repair many of the modern amps, their learning stopped with 1970's technology.

The HF oscillation is absolutely normal and in fact necessary for operation, this is the PWM residual from the modulator and is well within limits.

Power measurement is made using a THD analyzer, a gated sine wave and gated averaging detector, this is not normally used in a typical low tech repair shop and can easily result in erroneous measurement.

The output of the amp is not ground referenced, if the test equipment used is ground referenced than the readings will be incorrect.

Comparing the Shuttle combo to another amp/cabinet is not apples to apples. The Shuttle speaker is almost 100dB/1W/1M sensitivity, if the 410 has a lower sensitivity it could easily be less loud.

If the amp has been previously repaired and incorrect parts used, that can also contribute to the difference (I see it often enough to mention it, especially on amps sold via eBay).

PM me and I can provide the information on the factory service program.

 

[SWoods]

The typical repair tech does not have the necessary knowledge or skill level to repair many of the modern amps, their learning stopped with 1970's technology.

The HF oscillation is absolutely normal and in fact necessary for operation, this is the PWM residual from the modulator and is well within limits.

Power measurement is made using a THD analyzer, a gated sine wave and gated averaging detector, this is not normally used in a typical low tech repair shop and can easily result in erroneous measurement.

The output of the amp is not ground referenced, if the test equipment used is ground referenced than the readings will be incorrect.

Comparing the Shuttle combo to another amp/cabinet is not apples to apples. The Shuttle speaker is almost 100dB/1W/1M sensitivity, if the 410 has a lower sensitivity it could easily be less loud.

If the amp has been previously repaired and incorrect parts used, that can also contribute to the difference (I see it often enough to mention it, especially on amps sold via eBay).

PM me and I can provide the information on the factory service program.

The typical repair tech does not have the necessary knowledge or skill level to repair many of the modern amps, their learning stopped with 1970's technology.

The HF oscillation is absolutely normal and in fact necessary for operation, this is the PWM residual from the modulator and is well within limits.

Power measurement is made using a THD analyzer, a gated sine wave and gated averaging detector, this is not normally used in a typical low tech repair shop and can easily result in erroneous measurement.

The output of the amp is not ground referenced, if the test equipment used is ground referenced than the readings will be incorrect.

Comparing the Shuttle combo to another amp/cabinet is not apples to apples. The Shuttle speaker is almost 100dB/1W/1M sensitivity, if the 410 has a lower sensitivity it could easily be less loud.

If the amp has been previously repaired and incorrect parts used, that can also contribute to the difference (I see it often enough to mention it, especially on amps sold via eBay).

PM me and I can provide the information on the factory service program.

 

[SWoods]

Hi Aged horse,
My GB 9.0 has a very loud fan, which goes on upon startup.
Do you have any suggestions. Where can I get a replacement fan.
Or is something else wrong?
Thanks, Stu woods

 

[agedhorse]

Hi Aged horse,
My GB 9.0 has a very loud fan, which goes on upon startup.
Do you have any suggestions. Where can I get a replacement fan.
Or is something else wrong?
Thanks, Stu woods

It depends on where in the build cycle it sits. There was a factory update that included a new fan, machined sleeves, and baffle sheet metal. This is automatically installed at no charge beyond the flat rate service charge. It's also possible that the fan is failing, the fan control circuit is bad, or there could be other issues that are causing the fan control to mistrack (a very common cause when a user replaces the fan with something that has a different control curve).

PM me and I will send you information on the service program, this is the only way I handle repairs on GB products.

 

[jshinal]

I have gigged a Shuttle 9.0 for several years and had agedhorse repair it.

It will give you all the wattage and performance you expect, and it's not necessary to throw it off anything.