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 Post subject: NEWBIE TUBES QUESTION
PostPosted: 14 Apr 2017, 21:41 
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Joined: 14 Apr 2017, 21:27
Posts: 4
Location: Newfoundland
Hi All... Just found this site and forum, I Am an amateur ( hack) Musician...BUT!...over the years I have built a nice little recording studio in my home. Recently while scanning the classifieds I came across and ad selling a Roth Cocoon Tube Amp 2 channel 13w + 13W... with it came a set of Blueroom Pods... the ask was $150!!!... needless to say I snapped them up right away... Now for someone with the worst case of G.A.S. that you have seen... this may have been a mistake.... This is my first experience with a Tube Amp...needless to say, this little Amp has blown my mind... it combinded with the Bluerooms have breathed new life into old music... it like hearing these old song for the very first time...So... now I want more tube Amps, and I am considering trying my hand at a build... Sound like fun...and I can only imagine the personal satisfaction one would get from building a tube amp that sounds amazing.... So thats my intorduction... but the purpose for this post is... I am wondering, can I replace the tubes that came in the Roth Cocoon?... not that there is anything wrong with them or the sound.... but as i started researching tube amplification, it occurred to me that there may be better quality tubes that i can swap these ones out with?... who know maybe the ones in the amp are the best available... the tubes are.... CHINA 12AU7 ( 2 of these )..and CHINA 12AX7 ( 2 of these )...lol... just read that off the side...Now I am thinking there just might be better quality tubes out there...lol.. Any thoghts or suggestions are greatly appreciated. is it just that simply... natch the tube number and plug and pla with no other considerations?

Finally what are the recommendations for a Newbies "First Build " Amp?... I dont need alot of power.....not intertsted in loud so much as quality maybe 15-25 watts?.... DIY Kits anygood?

Any and all suggestions are welcome, thanks in advance

Paul

Newfoundland CA


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PostPosted: 15 Apr 2017, 15:26 
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Joined: 04 Jun 2008, 20:59
Posts: 3397
Location: Arizona, USA
Hi, Welcome to the glowing world of tubes. Yes I do believe I would swap out the tubes. There are many. Some tube vender sites have descriptions of the various tubes together with how they sound. While not one of my favorite sites Tube Depot has some descriptions of common tubes (the 12AU7 and 12AX7 are common tubes BTW). NOS (new old stock) tubes IMO do not necessarily sound better than new ones and the cost is generally quite a bit higher. I would stick to new production tubes at first. You didn't indicate what the output tubes were but they can be swapped as well. Lots of choices again.

For a starter project I would suggest something simple. Fender Champ designs are everywhere and will do to get your feet wet. They are low power, but simple to build and will teach you how to go about diy of bigger ones. Once you have it done (and working) you can move on to something serious.

Good listening
Bruce

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PostPosted: 15 Apr 2017, 20:10 
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Joined: 13 Feb 2013, 11:02
Posts: 37
Location: Canada
I agree with gofar. I would replace the stock tubes. They are adaquate, but there are far better.
Contact The Tubestore (www.thetubestore.com). They have a good selection of new manufacture tubes, and being in Canada, no brokerage fees.
Since you're new to tubes, go with new as opposed to NOS. Not only expensive, but you have to really know what you're doing to not get ripped off.

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Dan Santoni
DTS Audio Electronics
www.dtsaudioelectronics.com


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PostPosted: 17 Apr 2017, 10:31 
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Joined: 14 Apr 2017, 21:27
Posts: 4
Location: Newfoundland
Thats great Guys, thanks... I am Not sure of what the other tubes are... The am ps a stereo Amp ROTH COCOON MC4.... It does sound amazing. This weekend I was on the classifieds and Lucked into a Tube tester... its a protable Suitcase stylr model... It is a Moddel 3423 TRIPLETT TUBE TESTER.... the guys also gave me about 150 tubes with it, he says they have all been tested and all are working... There are a number of 12AU7A and 12AX7A They arre Sylvania 9 West Germany ) Gold Brand.... I havent bee through them all yet, but ther are all New in the Pkg
Also alot of GE Brand 6AU6A... BRIMAR 12AU7..... Alos Some SUPERIOR Brand.... At some point, I will build a Single Channel Guitar amp... but I am more interested in A Stereo Power Amp...L&R Channel with Power Switch and Volume Control.... what would be the suggested Schematics for this?... I spent the easter weekend watching 'Uncle Dougs" Videos On Youtube.. Amazing...explanations of how a tube amp works, from Input Signal to Sound out the speaker... he does the video in relation to The Fender Champ... After watching the Vids... I am even more excited about building my first Tube Amp...Any suggestions greatly appreciated.

Cheers

Paul
Newfoundland


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PostPosted: 17 Apr 2017, 11:09 
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Joined: 04 Jun 2008, 20:59
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Location: Arizona, USA
Hi, If the tubes actually are good..it may be a huge score. Many such are desirable and even as used tubes can command high prices. Good show.

Good listening
Bruce

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PostPosted: 17 Apr 2017, 12:12 
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Joined: 14 Apr 2017, 21:27
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Location: Newfoundland
The Guy I got them from was a Local trch, now retired... there is a Huge variety of Tubes he assured me that he tested them all and all are working. The tester is pretty amazing...near the bottom there is a detachable display filled with a roll of paper, that is a scroll that you turn the knob and a list of tubes displays, with all the specs for the tube number...not sure how to use this yet, but I am looking forward to figuring it out...I'd say it cost a pretty penny in its day. I am pretty excited about getting started...so step one for me is finding a schematic to build.... I am thinking two channel ( Stereo ) maybe 15 -25 watts per side...nt really interested in Volume...just sound quality. Hopefully I will come across something not too difficult, with a high quality of sound. I am finding schematics online...but its impossible for me to know whcih of the easier builds will be the best quality. Once I decise on the Amp to build, I am off to the races.

Paul


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PostPosted: 17 Apr 2017, 12:50 
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Joined: 05 Aug 2016, 14:35
Posts: 212
Sadly, that device is no more a tube amp than is my golden retriever. What it is, is a tube pre-amp (maybe) driving MosFet package amps for the output. Note that there are no output transformers, and the thing weighs about 4 pounds, kinda-sorta precluding the iron necessary for a 13-watt tube amp.

Try this: Remove one/both of the tubes for one channel - and see if this makes an actual difference. There are any number of Chinese amps out there that light up the tubes - and only light them up. Not suggesting that this is true of the Roth, but I cannot find a schematic anywhere, which leads to my question.

A few more clues:

Low B+. The thing has an outboard power-supply. So, nowhere near enough B+ to drive a power pentode.
No Line-out - meaning that you are stuck with the (likely) class D onboard amp chips to make the sound. Pretty much wiping out any advantage of the tubes anyway.

These things were obscenely expensive when-new, and, in my opinion, fraudulent if they actually called themselves "TUBE" amplifiers. Several ex-vendors call it a Hybrid. But quite a few went with the Tube Amp false flag. Roth themselves called it 'high-resolution pure tube sound' - which it isn't.

If you have a pristine device, perhaps you paid the right price that is, if you like the glow. But, for the record, I would not touch that thing on a bet.

VTA sells a good tube pre-amp and good tube power amp, kits or built.
Curcio Audio has options as well.
Parks audio will sell you boards, and give you some ideas.
There are many other and similar options.
There are a lot of legacy (vintage) options as well that will give you much more than what you have.


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PostPosted: 17 Apr 2017, 13:08 
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Joined: 14 Apr 2017, 21:27
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Location: Newfoundland
Yeah... I kinda wondered about the Amp...I cant find a schematic for it either... but have no fear... I will be pulling the cover off to have a "Look-See"...lol... its sold as a hybrid as you mention....as it is actualy an Ipod Dock.... the power supply is proprietary...and weighs about 1.5 Lbs...and the power plug has maybe 6 power contacts on it, so it not a simple wall wart device. The list price on it is about $770 US...so around $1100 Canadian.... and with it came a set of Blueroom Pods...very Funky looking British Speakers...they are Black and look like snowmen.... 3 balls stacked on top of one another... I am told they are pretty rare, and were a couple of grand new...lol...who knows.... hard to find pricing on them...but the whole set up sounds amazing, the Amp is like new, and I only paid $150 for the whol shot, so i think i did very well....but the big benefit right now is, that buying it has caused me to do some research, and as a result... not I am bent on building my own Tube Amp... I have A small workshop with A CNC,, as well a Metal Lathe, A Wood Lath and a Milling Machine, plus a coupe of Laser Cutter / Engravers, and a ton of wood working tools..... I am looking forward to building a nice Stage to mount it on as well... thast going to take a bit of woek, so I am hoping to find the right 2 channel design to put into it...should be fun.


Cheers

Paul
Newfoundland


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