Mike1959

Hi Myles, You may remember me from a few months ago (think my last post was in November 2005) regarding a sick Nomad 45 that had a gloomy prognosis! Well... I picked up the amp a couple of days ago and its good news. First off - the technician who repaired the amp is THE most respected MESA authorised engineer in the country - certainly in respect with MESA USA. All UK forum members who own a MESA amp take note: DO NOT entrust you amp to anyone else. Go to www.surreyamps.co.uk and contact Stan Lawrence. With the assistance of MESA USA (in particular a technician called Phet [silent h]), the amp has been returned to it's former glory and has been 100% certified. If you must go to another engineer, make sure that they are MESA authorised. Please dont make the same mistake I made I contacted someone who had an advert in UKs Guitarist magazine. He claimed he was qualified to repair MESA amps and had in fact restored a Nomad 45 for another client who was very satisfied. Fact he is not recognised by MESA and does not own the sophisticated equipment with which to undertake testing. Fact he charged me a lot of money for a botch-up, which only added to the ultimate cost and hassle of repairs. Fact he installed a fan and by law is required to ensure it conforms to regulations and supply a PAT certificate, which he did not without this certificate, the equipment cannot be played in public and all the associated legal liabilities. The total cost of repairs now stands at £400. It would have cost less than half that had I contacted MESA UK in the first place!! Stan Lawrence of www.surreyamps.co.uk determined that the amp had probably had a faulty capacitor since new (the original owner lied to me and I made the mistake of thinking it just needed new valves). The unauthorised engineer attempted to replace the capacitor but ended up damaging the main PCB with CU tracks pulled from the fibre-glass. Now to the good stuff. I have had a chance to play with this amp and here are my observations - Channel 1 is superb! Great clean and rock sounds abound. Channel 2 is my favourite in the normal power amp mode. But here is the interesting part switch the power amp voicing to extreme and channels 2 and 3 really opened up. I got some truly amazing low end grind with channel 3 in this mode. I havent had the chance to play it through an extension cab but I would imagine its awesome. Anyway, thank you Myles for your advice and support in the past. Truly appreciated! Best, Mike.

Myles, The tech told me that replacing the board is not an option. He wasn't specific when he spoke but I took it to mean that replacments are not available, as this model is discontinued. From what you say, I am now thinking he meant refitting them as an after service is not possible - something to do with the way they are fitted into the chasis. I will ask him to confirm. Thanks. Mike

Myles, I wish i'd known about that. It wasn't a deliberate attempt to not see an authorised Mesa tech. I saw an ad in the Guitarist magazine and gave them a call. Assuming the worse, PCB board is FCUK'd and the responsible party (previous owner or tech) don't want to know, and knowing that Mesa don't have any replacement boards, would you know if there is any chance of sourcing a replacement? I'm making a further assumption that even if I could obtain a replacment, it could be fitted? To think I could have bought three used 50 watt Marshall amps for the same initial outlay. I have invested so much money, time and effort, I want to exhaust all reasonable possibilities before I take the 'sell for parts' route. Once again, thank you for your trouble Myles. Mike

Hi Myles, I thought Id give you an update on the ailing Nomad. Spoke with the Mesa tech today. He hasn't finished his inspection yet but he was able to tell me what he had found so far - The opto-circuits are blown. He said these components should last forever; they don't generally go unless, as he put it, 'the amp has had a hi-voltage up it's backside'. As a result of the problems with the opto-circuits, channels 2 and 3 have channel 1 superimposed over them (I think that's the word he used). There is a 100Hz ripple that's very prominent in channel 2 - that's the low level modulation that I was complaining about. He also said that someone had botched a replacement electrolytic replacment. That is most likely the previous tech's handy work. Whilst I don't think he caused the problem, he assured me he had worked on Nomads before. He said he had repaired another clients amp, and he was very impressed with his work. I am very unhappy that he claimed to be able to service Mesa amps, but clearly didnt know how to either analyse the circuit and determine the problem, or replace components correctly. There is a possible short in the circuit somewhere. He is now awaiting some photos of the circuit boards from Mesa USA for comparison. He said sometimes you can zap the bridge with high voltage. AND THAT'S THE GOOD NEWS. If the PCBs are beyond repair, replacements are not available and the cost of repairing would be prohibitive, as in 'build an amp from scratch'. Once he has finished the inspection, he will supply me with a report and photographic evidence. If the amp cannot be repaired within reasonable cost, I will contact either the seller or the other technician, or both, depending on his findings. As it stands now it is not good. Ive spent £700 on the amp, and a further £200 for the service. Excuse me while I go and drown my sorrows Mike

Thanks Myles.

Hi Myles, Re: Nomad 45 I was going to take my amp to the MESA tech when I realised that he is located other side of London. And as only accepts between 10 - 5pm, it would have cost to 2 days annual leave to deliver and collect. I contacted UK distributor and they have given me the name of a more local tech. Not only that, I am told he is THE tech in the UK when it comes to complex tube circuitry. I had a long conversation on the phone. He is also aware of the sympathetic vibration issues with this amp model, particularly with heat affected components rattling. He also suggested a bad speaker (didn't think of that one) and the possibility of burnt out carbon resistors. Things are looking up again! I will deliver the amp to him this evening. Hopefully, I will have some good news by the end of the week. Mike

Myles, Thanks for the tip. I'll ask the tech to check for anything loose. I'm hoping to take it to the tech on Tuesday and pick it up later this week. I will post my findings. Mike

Hi Myles, Re Nomad 45 I spent a lot of time with the amp this weekend. Although there has been a definite improvement in the tone, there is still an underlying, raucous tone. Almost like a dissonant sound you get with a maxed fuzz pedal. But here's the thing, sometimes I can hardly hear it and other times I find it so bad. Also, when I can hear it, the low end is really mushy. Maybe this is just the way this map is meant to play, I don't know. I've owned Boogies before and the tone was always tight, even with the hi-gain settings. I will be taking it to a Mesa tech during the week to have it checked. If he finds nothing wrong then maybe it's just me! Perhaps I should just stick with Marshalls. Anyway, will let you know how it goes. Thanks. Mike

Thanks Myles. I will let you know how things turn out. Mike

Myles - will do. But in the meantime, if I could just trouble you again... I replaced the V5 with a 12AX7M and was impressed with the results. My understanding is that the long plate version outputs a high amplitude -which I think would drive the output stage harder. Changing #8s to #6s would make the tubes distort earlier? Or was there something more? By the way your web site has a ton of great info! I will, be browsing there from time to time. Hope to soak up a little bit of your wealth of knowledge. Thanks again. Mike

Myles, thanks will do. Though I'm not sure when that might be as I've sent the tubes back and I've decided to work with the #8s for a while. Get my moneys worth Mike

Hi Myles, Re: Groove Tubes UK I spoke with the supplier - he advised me he always orders matched quartets. They come taped together but he untapes them for packaging purposes. On inspection of the supplied tubes, I could see where he had cut through the tape. I told him that I was still concerned with the UK distributors comments; whether he was being straight or just humoring Joe Public I don't know, but he had put me off! I was really looking forward to installing these tubes and the whole sorry tale had taken the edge of it. The tubes have been returned for a refund. I'm hoping that the representative at guitarXS miss-communicated what actually happens, because I would like to be able to purchase Groove Tubes again in the future, but not from the UK distributor if what he told me is correct! Myles, I propose to contact GT USA to obtain clarification, unless you have any other suggestions. Regarding Saunders Stewart agency - all I can say is you must really love your job - well the three that I'm aware of Mike

Myles, Thank you for your response. This is exactly the same reason why I queried my order. The representative I spoke with at guitarXS.com was VERY CLEAR. He said that any pair of matched duets with the same # rating can be supplied as a quartet. He said, I would not be able to hear the difference between two pairs of duets with the same rating. This is very disconcerting as I paid for a matched quartet and received two boxes that were NOT TAPED TOGETHER. Considering the variances as per your posting, I may as well have purchased 4 matched JJs. Needless to say, I will be returning the tubes for a refund. But it would seem that GT UK are miss-selling your products. Now, it seems I am going to have to order directly from Groove Tubes USA in order to ensure I get what I pay for. By the way, had a quick peek at saunders-stewart-models, not that I do that sort of thing very often What's your connection with the them? Mike.

Myles, Regarding GT matched quartets - Spoke with the suppler. He informed me that GT no longer ship quartets in one box. He also said that GTs are the same as JJ's. Also spoke to guitarXS.com - UK distrubitor for GT. I was informed that a quartet is basically two deuts with the same rating, eq #6. I'm going to fit install them now, will post my findings later. Thanks. Mike

Myles, How do Groove Tubes ship their matched quartets of EL84S? I ask because I just received two sets of matched pairs and I was expecting one pack with a matched quartet - GT stipulate (on their website) that "All tubes are exactly matched into duets, quartets, sextets and even octets". Thanks. Mike

Myles, Appreciate your concern. The reading that I posted may be wrong as his memory was sketchy. In any case, I'd already decided that he is too far away and I've located a Mesa tech who is based locally. I will be taking the amp to him in the next few days. I've installed the replace V1 preamp tube and the 12AX7-M in the V5 position. I have noticed a significant improvemment; hi-gain settings are much more usable and musical. I recorded the amp yesterday and I'm quite pleased with tone - I was even able to achieve the famous Boogie controlled feedback. I think the icing on the cake will be #6s. Should have them in a couple of days and will let you know. Thanks again Myles. Mike

Hi Myles, Re: Nomad 45 Bias Spoke with the technician. Apparently he didn't do anything with the bias. He said the when he installed the GT-EL84S #8s the bias was pretty much spot-on at 25-26mA. He said that some of the soldering around the tube sockets was a bit dry so he resoldered where necessary, and replaced the output capacitors because, as he put it 'if they are not performing to spec they can cause abnormal low level noises' that this amp was suffering from. If my understanding is correct, I can install #6s without further modification. I will order some today - should be able to fit them and try out later in the week. I will say that - as it is now - the chan 1 clean settings has a nice chime to the tone. The tech said if I replaced the existing tubes with #6s I would lose some of that quality. That being the case, wouldn't I be able to swap them back if I wanted to record a cleaner sounding amp? Also, what effect, if any, will the GT-12AX7M have on the tone quality? Thanks again for your continued assistance. Mike

Myles, Re: Nomad 45 The Mesa tech asked me because the bias has been changed from stock. The tech who recently serviced the amp installed a bias circuitl, which I understant has been calibrated for #8s. So wouldn't it require setting back to stock - whatever that setting is?

Hi Myles, I have received today the replacement GT-EC833S and GT-12AX7-M tubes. I have installed them but I won't be able to try them out until tomorrow. I will let you know how it goes. It the meantime, I have contacted a Mesa Tech in London. He will perform the bias set up for the #6 tubes, but he is not familiar with these Groove Tubes and has asked what the bias voltage should be set to. Can you advise me? Thanks. Mike

Myles, Though my knowledge on this subject is minimal, I would agree with your reasoning as it makes perfect sense to me. I've order a replacement ECC83S and 12AX7M (wow- twice the price for the latter). I was 'quietly' feeling relieved when I played the amp today, having swapped the V1 and V5. I could get a really nice clean tone and the heavy gain settings were really aggresive but musical at the same time. This is exactly why I bought the Boogie in the first place. Once I've replaced the preamp valves and I am happy that the noise problems are resolved, I will replace the EL84s with #6s. I've got a feeling that the #6s may impart a softer top end - not so brittle. Damn I wish I kept with what you said in the first place and not be swayed by other peoples opinions. Mayybe the #8s would better suit a blues player as they do have have a nice sparkle to the tone. If all works okay, I will even consider a 1x12 ext cab for live stuff. Oh God - incoming GAS attack! Anyway, thanks again Myles for sticking with my problem. Much appreciated. Mike

Hi Myles, Spoke with John as suggested. He told me to return the amp to stock - remove the bias circuit etc. Basically he said that the amp circuit was designed to run with fixed bias and I could install hotter or colder tubes without worrying. When I asked him about Mesa not matching their El84's he said there was no need due to the inherent tolerences in the tube design, or words to that effect. I played the amp briefly again today - having swapped V1 and V5 - and I must say that there was a definite improvement: much tighter and more musical higher gain. Will try again over the next few days to see if change is consistent. I have ordered a replacement ECC83S, but was wondering about a long plate version you mentioned in an earlier posting. Is this a GT offereing and what model is it? Thanks. Mike

Bump.

Thanks Myles, will do that. Mike.

Hi Myles, Regard the Nomad 45 - Sorry, I think I messed up the postings. I spoke with the technician who performed the service. In a previous post I said he replaced the filter caps, but I think that should be output caps. He thinks the problem lies with one of the preamp valves. I've tried swapping V1 and V5 but I couldnt tell for sure as I wasnt able to play at full tilt, so will have to wait until this weekend to confirm. In the meantime, I've ordered a backup GTECC83S. I also contacted Mesa and asked them if the drop in volume from chan 2 (vintage) to chan 3 (modern) is normal. He couldn't say for sure and suggested I try a side by side comparison with another Nomad 45. If anyone on this board has a Nomad 45, I would appreciate it if you could verify this finding. I also enquired about the problematic J175 semiconductors (?) and the known problems with some inferior quality components that found their way into the Nomad range. These SC are used as channel mutes - when they leaked they would cause problems such as volume loss. He also suggested tugging on the pots as that would identify a fault that could cause a volume change. I will post again when Ive tried the above. Thanks again for your time. Regards Mike

Mike You are very welcome. Let me know what you find. Hi Myles, Having discussed the problems i was experiencing with a technician, I decided to have the Nomad serviced. The technician discussed my requirements with Groove Tubes and installed GT replacements preamp and poweramps tubes. The GTEL84S valves are #8's to give me the tighter low-end. A bias circuit was installed and the stock filter caps were replaced with higher spec caps. The technician suggested that the stock caps can cause the problem I was experiencing. I also had two fans installed to prolong tube life and reduce the likelyhood of the board getting fryed. I went to collect the amp yesterday, listened to the results - there was a definite sparkle in the tone . It seemed that the effort and money was well spent until I got home and put the amp through it's paces. Tried all the various settings as per the manual and this is what I found - There is a nasty low-end resonance like an electrical noise that's prevalent when playing the wound strings. It is not so apparent with cleaner settings on channel 1. Although there has been some improvement to the high gain settings with more sustain, it doesn't have that Boogie singing quality. At high gain settings, the low end still sounds a bit woolly with a brittle mid to high end. When I tried to obtain a controlled feedback, all I get is a pulsing microphonic squeal. I recorded the amp for a project I'm working on - that was when the symptons were really apparent. If it would help in any diagnosis, I could provide an MP3. I will discuss my findings with the amp technican on Monday. But I have to say, my heart sank when I played it in anger today. Did I make a mistake in having #8's fitted as opposed to your suggested #6' (though I can't see how that would cause the problems I'm describing). Any advise/diagnosis would be very much appreciated. Regards, Mike Hi Myles - just wanted to add another observation. Comparing channels 2 and 3, I set up the gain, vol and tone controls exactly the same, with chan2 set to 'Vintage' and chan3 set to 'Modern', I would have expected chan3 to be louder. Not so. Chan3 is significantly quieter, and when I set it to 'Vintage' it is even quieter. So much so that it cannot compete with chan1 set to 'Clean'. Thanks again in advance. Regards Mike