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Post by kledbet on Nov 22, 2005 17:41:51 GMT -7
OK I promised to get back to you about this and here is the result. My amp now has NO ghost notes and in my opinion sounds great. Whenever you talk about adding something to any amp you run the risk of either upsetting those who either build the amp, or offending those for whom the amp works great. The bottom line is that at least on some of these amps the ef86 tube occilates when the volume runs high. This can be fixed by adding a small stabilization circuit to the ef86 tube. The cost is about $50 for the job to be done or if you are good with this yourself then you can contact Dan at (650) 571 6887 and talk to him about all of this.... I am not an expert. Here are the things I tried to fix the amp with no success: 1. New NOS tubes in all positions 2. Dampening the ef86 tube 3. Moving the head away from the speaker 4. Lowering the bias on the KT66 tubes All I can say is that now the issue for me is gone and I love the sound of the amp, the ghost notes at least for me was to much to put up with. If you don't have this problem, that's great, don't fix what is not broken. If like me you amp sings out a note a 6th lower than the note you are playing then at least you have an option of discussing it with the tech. Good luck to all of you and many thanks to the good Doc for a great amp.
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dewman
Junior Member
Posts: 86
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Post by dewman on Nov 22, 2005 19:28:09 GMT -7
Thanks- will call Dan to see what he did and possibly do the A/B test myself. Glad the problem is fixed for you, hope the tone remains great and the mod did the trick without sacrificing anything. Thanks for bringing this to the forum's attention!
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Post by kledbet on Nov 22, 2005 23:20:36 GMT -7
Great let me know the result when you try it out. After talking with Dan he is going to make a kit available to all who want to try it. I think the kit with instructions is about $35-$40. I know Dan said the problem was not in the filter caps as has been suggested by several others, but rather in the way the ef86 tube was responding in the circuit. As I mentioned before the stereo amps built in 1957 using an ef86 tube sometimes had this same issue, and the stabilizing circuit was added to those designs as well with great success. By the way if you play with a closed back cab you will not hear the occilations as much as you will hear them in an open back cab, also less efficient speakers also minimize the problem. I will keep playing the amp tomorrow and if I hear any negative changes I will be sure to let you know.
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Post by taswegian on Nov 23, 2005 0:05:58 GMT -7
By the way if you play with a closed back cab you will not hear the occilations as much as you will hear them in an open back cab, also less efficient speakers also minimize the problem. I play through a closed back stock Z-Best so maybe that explains the lack of ghost notes with me, plus some serious valves... I'd still check with the Doc as we 66'ers have a lifetime warranty if you are the original owner and this mod may nullify that.
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Post by DRZ on Nov 23, 2005 5:06:48 GMT -7
Hey guys before his gets out of hand, I'd like to see this mod. At this time I don't recomend it only because I have never seen it and what it does.
Also I 'm having little trouble believeing the high freq snubing circuit will remedy a low freq 120hZ harmonic ailasing.
Could be true could be snake oil.
DR.Z
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Post by myles on Nov 23, 2005 10:52:43 GMT -7
This is sort of an interesting subject that is really pretty complex.
Ghost notes can be brought on by all sorts of things. Before I'd mod a Route 66 I would try a few things. Amps are very interactive in nature and if this mod has something to do with the EF86 the first thing I'd do is try a new good EF86. Bad ones that are physically microphonic can cause all sorts of havoc. The Z amps such as the Z-28, Route 66, KT-45 and Delta 88 are the most forgiving amps of any that use an EF86 but just the other day I had an NOS Dario Miniwatt go south in one of my amps.
Second ... make sure your output tubes are matched and in good shape. Make sure the bias is set properly. You will find this can also cause what can appear to be ghost notes or something like that.
When you change output tubes also think about changing your phase inverter.
Most ghost notes are caused by an amp being "under capped" or has bad caps in the power supply. When designing an amp it is a really delicate balance of "how much to cap" the power supply. Too little and you have issues like ghost notes. Too much and the amp has no life and is constricted. This is pretty famous in the old non-master Marshall amps. The early ones had less filtering than later ones. At one point there were six big blue filter caps sitting on top of the chassis of these amps. After hearing the results in many amps Marshall dropped back to 4 of the big LCRs on later amps. The Marshall JTM-45 reissue has two 50/50 caps. One of the biggest improvements one can make to these amps is a 32/32 and 26/26.
The Doc has the Route 66 in a really great state of balance. I would not change the amp personally. What I would do if I had any ghost note issues with my Route 66 clients would be to change the output set, rebias, check the caps in the amp and change the EF86. The bias would be done first as that is no cost for my clients, and then I'd check the EF86.
The Route 66 is one amp that I do not even own. The reason I do not have one is because it is one of the most prolific amps that my own clients have. I see lots of these on tour and in general use. I don't need to own one as I know so many folks that have them and will let me use them when I'd like to do that. I think the amps are a real icon in the amp world and love them just the way they came from the good Doctor.
I think there are too many factors that can manifest into ghost notes or something that behaves as ghost notes. What I would suggest to the fellow that started this post would be ... send one of these things to the Doc and try to get his take on it. I don't think he has a lot of extra time but he might be game.
For anybody in this forum that is in my area (So Cal) ... or will be in the area, I would be more than happy to check out anybodies Z amp for free and if a class A/B amp check and adjust the bias if necessary at no charge. I will also let you try a few different EF86s so you can see for yourself what these can do.
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Post by ducmike on Nov 24, 2005 7:05:44 GMT -7
Is there an authorized Dr Z service tech in the Dallas, TX area? The ghost notes don't bother me enough to risk shipping, but I would like to get a check-up to be safe.
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Post by kledbet on Dec 3, 2005 13:17:57 GMT -7
OK I need to amend my earlier post. I think it is important to be honest and so it is necessary for me to say that my ghost notes are not completely gone. My initial listening after the mod, was done on other equipment, and not my own cabs. After playing the amp at home it did not take long to realize that the ghost notes were still there and the mod did not totally remove the problem. I wish there was a fix that everyone new about that would take this away, but there isn't. This topic of ghost notes in the 66 is the 2nd most read topic in the Route 66 forum, I would guess its because many players are aware of this issue. If at any point I come across what the real problem is I will return to the forum with the answer. Thanks for the kind spirit of everyone who chimed in on this topic, my desire was to help, not put down anyone. Good luck, and play on.
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Post by ducmike on Dec 4, 2005 8:24:48 GMT -7
kledbet, have you sent the mod info to DrZ?
And a bump for the tech in Dallas question.
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Post by kledbet on Dec 5, 2005 9:30:28 GMT -7
No I have not sent Dr Z the mod info, as it is owned by the tech. I don't read nor understand schematics but if I do get a copy of it I will forward it on.
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