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Post by kruzty on Feb 14, 2006 21:05:56 GMT -7
Is it OK to use a 12AT7 as the phase inverter in the Ghia? I just got mine today (from eBay) and want to change some tubes. Thanks in advance for the info.
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Post by guitarman1 on Feb 15, 2006 7:06:03 GMT -7
It won't cause any damage krusty, if that's what you mean by "OK".
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Post by zdogma on Feb 15, 2006 7:14:21 GMT -7
I tried it and it didn't sound so good, but I'm not sure if it was a matched tube like miles recommends. It lost some of that nice midrange sound, and there seemed to be less output tube breakup.
I'll be interested to hear your impressions.
Any particular sound you're trying to get?
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Post by kruzty on Feb 15, 2006 7:33:06 GMT -7
Yes, I mainly meant "would it do any harm." I don't have a particular sound in mind, I just have a few Mullard 12at7's lying around that I used in my BiValve. I liked them in the driver position there, but that was different than a phase inverter. I'll give it a shot and see! Thanks for the response, guys.
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Post by myles on Feb 15, 2006 11:35:57 GMT -7
I do not like the AT7 as it is too "stiff". The gain is about the same as a 5751 and the 5751 is a much nicer tube.
The 12AT7 will also run very hot as the Ghia has a unique feature that is generally not seen in other amps, even Z ones ... a fixed bias phase inverter. I stay with the 5751 or 12BH7 for a sort of more clean headroom jazz tone.
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Post by kruzty on Feb 16, 2006 7:05:02 GMT -7
Thanks for the info, Myles. I'm going to try a balanced 12BH7 from Mike to give a little more clean headroom.
Would a higher GT rating for my EL-84 tubes give more clean headroom, as well, or would that negatively affect other things about the amp? Mine came to me with some old Mesa tubes and I replaced them with a pair that was in my Blues Jr. They are white, which is the medium GT rating. As soon as I got the Blues Jr. I replaced the stock tubes (GT Sovtek's) with GT EL-84S (JJ's), so I had those to use. They sound worlds better then the Mesa tubes, but would the JJ's and/or higher GT rating make much of a difference?
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Post by guitarman1 on Feb 16, 2006 7:56:43 GMT -7
I do not like the AT7 as it is too "stiff". The gain is about the same as a 5751 and the 5751 is a much nicer tube. The 12AT7 will also run very hot as the Ghia has a unique feature that is generally not seen in other amps, even Z ones ... a fixed bias phase inverter. I stay with the 5751 or 12BH7 for a sort of more clean headroom jazz tone. What kind of tone does a 12BH7 give to the Ghia Myles? Can you recommend any particular new or nos brand?
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Post by Curt on Feb 16, 2006 14:22:06 GMT -7
Thanks for the info, Myles. I'm going to try a balanced 12BH7 from Mike to give a little more clean headroom. Would a higher GT rating for my EL-84 tubes give more clean headroom, as well, or would that negatively affect other things about the amp? Mine came to me with some old Mesa tubes and I replaced them with a pair that was in my Blues Jr. They are white, which is the medium GT rating. As soon as I got the Blues Jr. I replaced the stock tubes (GT Sovtek's) with GT EL-84S (JJ's), so I had those to use. They sound worlds better then the Mesa tubes, but would the JJ's and/or higher GT rating make much of a difference? LOL Man I hear ya !! My Ghia came off the 'bay w/Boogie tubes too ............YUCK !!!!!! Can ya say DARK?!?!?! JJ's from KCNOS along with a balanced RCA long plate 5751 and a NOS 12AX7..Bliss !
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Post by myles on Feb 17, 2006 18:57:34 GMT -7
Thanks for the info, Myles. I'm going to try a balanced 12BH7 from Mike to give a little more clean headroom. Would a higher GT rating for my EL-84 tubes give more clean headroom, as well, or would that negatively affect other things about the amp? Mine came to me with some old Mesa tubes and I replaced them with a pair that was in my Blues Jr. They are white, which is the medium GT rating. As soon as I got the Blues Jr. I replaced the stock tubes (GT Sovtek's) with GT EL-84S (JJ's), so I had those to use. They sound worlds better then the Mesa tubes, but would the JJ's and/or higher GT rating make much of a difference? The BH7 is a fun tube in the Ghia. The Blues Jr.... stick with the mid ratings. Remember, this is one of the few EL84 amps that is NOT a cathode biased amp. It is fixed grid biased and has no adjustment and works best with mid range (4-6) tubes. Fender used the EL84 rather than a 6V6 as the EL84 was cheaper. The Mesa are generally the darker Sovteks and the JJs are much nicer in these amps (or any EL84 amp from my point of view).
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Post by myles on Feb 17, 2006 18:58:54 GMT -7
I do not like the AT7 as it is too "stiff". The gain is about the same as a 5751 and the 5751 is a much nicer tube. The 12AT7 will also run very hot as the Ghia has a unique feature that is generally not seen in other amps, even Z ones ... a fixed bias phase inverter. I stay with the 5751 or 12BH7 for a sort of more clean headroom jazz tone. What kind of tone does a 12BH7 give to the Ghia Myles? Can you recommend any particular new or nos brand? The BH7 will give the amp less agression and more clean headroom. Any NOS 12BH7 is great but get them from a good source that tests them. Mike at KCA is great for these.
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