Spongy mode is dead on Roadster

[dancutmore]

Hi guys,
I am pretty much a noob when it comes to tube amps. I have a Roadster 2x12 combo and normally played it on Bold mode but got a bit adventurous with the amp the other day and discovered that 'spongy' mode is dead for lack of a better word. I get sound out of it but all channels sound like clean channels muffled. When I flick the switch back to the off position, I get a second of what the channel should sound like. Does anyone have any ideas on what this could be? Just to throw it out there, I bought this amp from a guy in the US and in order for me to use it in Australia, I have it plugged into a step down transformer. Not sure if this has anything to do with it, but it can't hurt to give you guys all the info. Also, I am pretty sure I have had it play through spongy mode before with no dramas. Any help would be appreciated.
Dan

 

[screamingdaisy]

Could be a loose wire or corrosion on the switch.

 

[jbird]

The spongy mode works by lowering the incoming voltage...And your using a step down transformer...I don't like the mix...I'm not sure I would diagnose the amp or the circumstances?

 

[dancutmore]

What do you mean you are not sure you would diagnose the amp or circumstances? You aren't going to be held accountable. Any help or ideas/knowledge would be appreciated. I know it isn't ideal to have the setup the way it is. but the transformer just brings the voltage from the 240v in Aus to the 110v(I'm pretty sure) you guys have in the US. which is what the amp needs. Besides, it has worked fine in the past in spongy mode

 

[domct203]

Welcome to The Board.

As long as your step-down transformer is at least 500W you should be fine. Spongy mode is simply another tap on the primary side of the power tranny, it does not care if the step-down transformer is on a utility pole outside or in the room with the amp.

This could be a preamp tube issue, some brands do not like the lower voltages of Spongy mode, and will "drop out".

Do you have any Tung-Sol reissue, Mullard reissue, Electo-Harmonix, Sovtek or Mesa Russian1 or Russian2 12AX7's in there? This is a known issue, especially in the V3 & V5 positions (cathode follower).

Are you using the FX loop? If yes, Hard-Bypass it and see if anything changes.

Report back and we'll keep trouble-shooting.

Dom

 

[domct203]

The spongy mode works by lowering the incoming voltage...And your using a step down transformer...I don't like the mix...I'm not sure I would diagnose the amp or the circumstances?

Then why bother to post in the thread?? I'm not flaming, just sayin'.

The step-down tranny, if correctly sized, will have no ill-effect on the amp. It is no different (in the US) than the (large) step-down transformers at the tops of utility poles that drop the high voltage transmitted by the utility company down to the 220V that enters your home and is phase split to 110V that reaches your outlets.

Dom

 

[dancutmore]

The spongy mode works by lowering the incoming voltage...And your using a step down transformer...I don't like the mix...I'm not sure I would diagnose the amp or the circumstances?

Then why bother to post in the thread?? I'm not flaming, just sayin'.

The step-down tranny, if correctly sized, will have no ill-effect on the amp. It is no different (in the US) than the (large) step-down transformers at the tops of utility poles that drop the high voltage transmitted by the utility company down to the 220V that enters your home and is phase split to 110V that reaches your outlets.

Dom

Could not agree more!

Thank you very much for the advice, it is funny you should mention the hard bypass switch, I have only just found out what it does a couple of days ago. I have it set now to hard bypass and unfortunately it has made no difference. When I get home this afternoon I will check out the preamps as they certainly could be the issue. When I first got the amp I had a tube issue and got some replaced by a tech guy and I haven't investigated what he put in. Pretty silly of me I know, but like I said, bit of a noob here. I didn't realise how touchy these mofos are. Again thanks for the advice and hopefully I can get this mother pumpin again!!

 

[domct203]

Here is some more info on the Cathode Follower positions.
http://forum.grailtone.com/viewtopic.php?f=4&t=25102&start=19
It appears anything made by New Sensor Corp have shown to fail in cathode follower use. New Sensor brands include those I mentioned previously (Mesa used Sovtek for their "Russian 1" & Electro Harmonix for their "Russian 2" 12AX7). Any NOS, Chinese or JJ are fine.

If this is effecting all channels I would start swapping with V1, V3 & V6 in that order. Get a known good 12AX7 and swap it into V1. If that doesn't change anything replace the original tube and move on to V3, then V6 if needed.

Once this is worked out I would consider at least new power tubes. You have no idea of the condition of the current ones, being a used amp.

Dom

 

[dancutmore]

Well, I got all up in the guts of the amp and pulled out a couple of preamp tubes and sure enough there were a couple of eh's in there from russia I think (slovak?) There were also a couple of the original Mesa's in there. When I went to do a bit of swapping around I accidentally bent a couple of the prongs on them and of course when I went to bend them back I busted two of the tubes so now I have only got 4 good tubes left Which I don't think is enough to even get sound right? Anyways, I have decided to just retube the dam thing. Looking at Doug's tubes and trying to decide between the metal and hard rock set. I normally play anything from Tool,System,Mastodon to Chilis,Pearl Jam, Nirvana. I was thinking the Hard Rock sounded more versatile. Above all though I really want that chug when you palm mute you know? Again, any advice would be great!

 

[domct203]

If you are bending tube pins you are using too much force on the tubes. Gently rock the tube in a small circular motion when removing/installing. Be especially carefull on the power & rectifier tubes, they have a keyed pin on the (brittle) base that is easily broken off if not aligned properly.

Alot of players here (myself included) feel that the Tung-Sol reissue sounds great in V1 (The Tung-Sol is fine here, but don't use one in V3 or V5 ).

Doug's sets are a decent set of tubes, and his customer service is very good. Regardless of the set you order, the standard Dual Rectifier uses 5 preamp tubes, your Roadster uses 6. Be sure to discuss this with Doug before you order so you are not short 1 tube!

Dom

 

[dancutmore]

Again, it is funny you say that as about an hour ago, I sent him an email regarding that very thing lol. I thought it was weird his kit only mentioned 5.
In regards to the pins, one might say I am a bull at a gate with these things and unfortunately it is a case of lesson learned the hard way. Now I don't have an amp to play at all until the tubes turn up
Again thank you so much for you help, you are a wealth of knowledge

 

[dancutmore]

Just thought I would check in and let you know that all is fixed and turns out you were spot on!! New set of tubes turned up, installed them and nothing worked. Had a look and the sovtek in v6 wasn't lit so I took it out and replaced it with an old one of mine and hey presto, the amp is alive again. Both on spongy and bold. Never sounded better by the way. I am absolutely in love with it now and am shocked that it can sound so much better without even messing with any settings. I mean, this thing is f@$king wailing!!!! Just going to see if I can get the sovtek replaced and I will be happy as Larry!!! Thank you soooo much for your help, you have helped me realize why I spent nearly $4.5k on this thing!! I did have my doubts!!

 

[domct203]

I'm really glad that I could help, and that it all worked out good.

Every time that I start to guess if the Roadster is really for me I just turn it up a little louder and realize it is a perfect fit!

Rock-on!

Dom

 

[ryjan]

I love happy endings.

 

[ironjose]

did you change the power tubes as well?... and by the way i hate the cathode followers !!! hahaha lol
im glad your amp got fixed!!!

 

[jbird]

So what tubes did you go with?

 

[dancutmore]

Went with the hard rock preamp kit from dougs tubes and the ruby 6l6gcmstr's. hope this helps, it helped me for sure!!!