[430011]

A bit off the current topic:
I know it has been discussed before, but what is the consensus on adding ventilation to the case of the amp? I was thinking of drilling a pattern of small holes in the case in the space just behind the 12AU7 tubes and around the octal sockets. It seems to be the hottest part of the case. Then drilling holes or using perforated aluminum sheet in the bottom of the case to allow convection heat loss. Would there be a negative impact on RFI rejection? it seems unlikely that would be a significant concern.
 
Generally the amp doesn't get too hot during normal outside temperature days and I don't think about it. However, here in western WA we have been experiencing some 90+ days which means a very warm living room since A/C isn't really a thing here. On those days the amp case gets very hot indeed. sometimes I'll run a small computer case fan on it, but I don't love that solution. I know that class A tube amps run hot, but this is bordering VERY hot. Thanks!

 

[lucidreamer]

  A bit off the current topic:
I know it has been discussed before, but what is the consensus on adding ventilation to the case of the amp? I was thinking of drilling a pattern of small holes in the case in the space just behind the 12AU7 tubes and around the octal sockets. It seems to be the hottest part of the case. Then drilling holes or using perforated aluminum sheet in the bottom of the case to allow convection heat loss. Would there be a negative impact on RFI rejection? it seems unlikely that would be a significant concern.
 
Generally the amp doesn't get too hot during normal outside temperature days and I don't think about it. However, here in western WA we have been experiencing some 90+ days which means a very warm living room since A/C isn't really a thing here. On those days the amp case gets very hot indeed. sometimes I'll run a small computer case fan on it, but I don't love that solution. I know that class A tube amps run hot, but this is bordering VERY hot. Thanks!

 
I also considered adding a silent fan on top of the case but then discarded the idea since any fan would introduce noise and I often listen to the music at low volumes. I do not know if there are any tube amplifiers with open tube design that have cooling fans.
You may consider using a pair of socket savers for the power tubes as I did. they have no effect on the audio quality. Hard to believe but it does reduce the overall temperature of the metal case a little bit because the heated glass bulb is risen about an inch from the top plate and tubes stay cooler too. I could tell the difference by touching the bases of the tubes before and after installing the socket savers.

 

[lucidreamer]

Just arrived a pair of Philips 7581A NOS tubes that I got on eBay lately and these tubes are built like tanks and just ooze quality! They are bigger than GE 6L6GC too and the connectors inside are pretty solid and thick, real MIL-spec type of equipment. I put them in and the sound struck me as super-clean and detailed, the highs are very articulate and pronounced and the bass feels very tight, probably the best I ever heard in a tube amp. Now I understand why many recommended this tube for bass amps especially. I think I will stick to that tube for a while, just want to see if the sound will mellow out a little bit during the break-in, the highs seem to be on the border of fatiguing at times especially with the Fostex speakers (up to 40kHz driver range). If listening for that kind of sound will prove to be fatiguing after several hours, I will probably put them in the drawer or sell them later. What is funny is that those tubes were so abundant before and in the 60-70's they were sold for a penny, something like 2-5 bucks each. These days they are sold for $120 each in stores.
But so far - pretty happy with that tube overall! Thanks for your recommendations guys, really appreciate it!

 

[JK-47]

Thanks for the tube updates Efussion and lucidreamer,
 
I'll have to try me GE 5814's again soon. I haven't had then in in months. It's mostly been the 6189 Philco/Lansdale's (more detail and resolution), and Amperex 7316's (warmer midrange and holographic soundstage) lately...
 
I have some Philips input tubes on the way, and will fill you guys in on the sound when I get home from work in 3 weeks...
 
Blue 6189's and Green 5814's
 
lucidreamer,
 
Like all tubes, sometimes they need time to settle or different paring on the input tubes to tune the sound slightly. My critical tube listening is always done with headphones, so I'm sure to have the whole frequency spectrum represented. That might be hard to do with small full range speakers.

 

[catcherfly]

Hi All,

I am looking to buy some RCA 12AU7A Clear tops and a pair of power tubes. Currently I am running Philips 7581A 6L6GC and Amperex 12AU7 Orange Globe tubes in Ultralinear mode. Do any of you have suggestions for other power tube options to try out?

Here is a link for some Clear Tops. Any thoughts on these? They are from the 70s and I don’t know if the Clear tops are still worth it post 60s. http://www.ebay.com/itm/RCA-12AU7A-ECC82-Clear-Top-Tubes-Matched-Pair-Tested-NOS-NIB-Matched-Codes-/261962447366?pt=LH_DefaultDomain_0&hash=item3cfe2dba06

Any thoughts would be greatly appreciated!

After 20 years as an artist I have decided to open an audio equipment, audio furniture, and record store (web and retail) in Portland Maine. The TU-8200 has had a lot to do with this choice! I am trying to finish up some prototypes in the next few months including a turntable, a line of Rock Maple furniture, a line of speaker cabinets with Audio Nirvana drivers, and a speaker/subwoofer selector box. For now I am using my home as a showroom and I’ll post some high quality pictures when I install the Maple equipment/record units and the finished speaker/sub selector box. In the meantime, here are a few pics and videos!

Thanks,
Joe








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[VIDEO] IMG 0470 from K|M|A on Vimeo.
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[JK-47]

Nice set up catcherfly

 

[catcherfly]

Nice set up catcherfly

Thanks JK-47!

I am continually amazed at how good the TU-8200 sounds. I have two pairs of speakers hooked up to the 8200 and it effortlessly fills the entire apartment. I have also stopped listening to my HE-400i through my Audio-GD balanced headphone amp in preference for the 8200.

Can anyone recommend a store or reliable eBay seller for tubes? After hearing Lucidreamer's, and other's, stories I am a bit nervous, especially without a tube tester.
And again, can anyone recommend some power tubes? I am currently running Philips 7581A 6L6GC with Amperex 12AU7 Orange Globe.

Thank you!

 

[lucidreamer]

Can anyone recommend a store or reliable eBay seller for tubes? After hearing Lucidreamer's, and other's, stories I am a bit nervous, especially without a tube tester.
And again, can anyone recommend some power tubes? I am currently running Philips 7581A 6L6GC with Amperex 12AU7 Orange Globe.

 
Hi Catcherfly!
 
Congratulations on the Elekit setup, looks really nice with Nirvana Audio speakers! The full-range speakers with Elekit tube amplifier is a match made in heaven!

 
As for the power tubes - It really depends what kind of sound you are trying to pursue. I would say that Philips 7581A that you already have is one of the best NOS tubes out there for me. I currently use these tubes too since last week as they were brand new when I bought them and now just keep opening up terms of the sound. Really clean and tubey sound that they output. I even noticed that they starting glowing blue much more now than they did when I just put them in in the first day. The same blue glowing starting showing with my other TAD new production 6L6GC tubes after they burned in a little bit, so it must be  a good indication of new tubes. 7581A have the best bass sound for me compared to other tubes.
 
Another great NOS choice, if you prefer a little warmer and laid-back British sound is EL34 but they are harder to come by in NOS state, especially XF1 or XF2 made by Mullard Blackburn factory. I have only listened to XF1 and XF2 double and single getter ones but other NOS EL34 are supposed to be great as well, there is lots of information about them on the internet. If you are looking to buy EL34 - I would recommend http://www.cathedralstone.net/Pages/MullardEL34finalm.htm, Michael really knows his stuff and can help you with your tube selections.
 
For the input tubes - I really dig the RFT 12AU7 ones. Westinghouse black plates are great too with very open and spacious sound but RFT sound cleaner and more dynamic. There was a site on the internet, I cannot remember which one at the moment, where there was a table comparing the sound character between different 12AU7 brands. I will try to find and post it later. RCA 12AU7 - I read somewhere that it is not as good as Westinghouse, but they could be different tubes too.
 
Please keep up posted on your experiences with tube rolling, etc.

 

[JK-47]

Thanks JK-47!

I am continually amazed at how good the TU-8200 sounds. I have two pairs of speakers hooked up to the 8200 and it effortlessly fills the entire apartment. I have also stopped listening to my HE-400i through my Audio-GD balanced headphone amp in preference for the 8200.

Can anyone recommend a store or reliable eBay seller for tubes? After hearing Lucidreamer's, and other's, stories I am a bit nervous, especially without a tube tester.
And again, can anyone recommend some power tubes? I am currently running Philips 7581A 6L6GC with Amperex 12AU7 Orange Globe.

Thank you!

 
Hmmm... a reliable ebay seller... that can be a tough one. Originally I looked at buying tubes in a few ways; pay a premium and buy from a few online retailers that claim they test and match etc. , roll the dice on ebay, buy a tube tester or testers and know 100%  that I was getting what I was paying for. In some case I have had to send replacement tubes back to the seller, and have heard almost every excuse in the book.
 
I will say that my testers have already almost paid for themselves in the span of less than a year (my 2 new testers have, but not my vintage Hickok yet). They have enabled me to return duds, non matched pairs, and micro-phonic input tubes, with little or no argument from the seller. Almost 1 out of 3 sets of vintage tubes I buy have problems or are not as advertised, not too mention I can buy single tubes and match them myself. I prefer the term vintage when talking about older tubes, I feel "NOS" (New Old Stock) is grossly over used and misleading. Very few old tubes are actually untouched and mint...
 
In the end it's up to you. The world of tubes is very murky, but oh so rewarding

 

[catcherfly]

Hi Catcherfly!

Congratulations on the Elekit setup, looks really nice with Nirvana Audio speakers! The full-range speakers with Elekit tube amplifier is a match made in heaven!

As for the power tubes - It really depends what kind of sound you are trying to pursue. I would say that Philips 7581A that you already have is one of the best NOS tubes out there for me. I currently use these tubes too since last week as they were brand new when I bought them and now just keep opening up terms of the sound. Really clean and tubey sound that they output. I even noticed that they starting glowing blue much more now than they did when I just put them in in the first day. The same blue glowing starting showing with my other TAD new production 6L6GC tubes after they burned in a little bit, so it must be  a good indication of new tubes. 7581A have the best bass sound for me compared to other tubes.

Another great NOS choice, if you prefer a little warmer and laid-back British sound is EL34 but they are harder to come by in NOS state, especially XF1 or XF2 made by Mullard Blackburn factory. I have only listened to XF1 and XF2 double and single getter ones but other NOS EL34 are supposed to be great as well, there is lots of information about them on the internet. If you are looking to buy EL34 - I would recommend http://www.cathedralstone.net/Pages/MullardEL34finalm.htm, Michael really knows his stuff and can help you with your tube selections.

For the input tubes - I really dig the RFT 12AU7 ones. Westinghouse black plates are great too with very open and spacious sound but RFT sound cleaner and more dynamic. There was a site on the internet, I cannot remember which one at the moment, where there was a table comparing the sound character between different 12AU7 brands. I will try to find and post it later. RCA 12AU7 - I read somewhere that it is not as good as Westinghouse, but they could be different tubes too.

Please keep up posted on your experiences with tube rolling, etc.

Thanks a lot for your suggestions Lucidreamer. I will definitely spend some time on the Catherdral Stone site

 

[catcherfly]

Hmmm... a reliable ebay seller... that can be a tough one. Originally I looked at buying tubes in a few ways; pay a premium and buy from a few online retailers that claim they test and match etc. , roll the dice on ebay, buy a tube tester or testers and know 100%  that I was getting what I was paying for. In some case I have had to send replacement tubes back to the seller, and have heard almost every excuse in the book.

I will say that my testers have already almost paid for themselves in the span of less than a year (my 2 new testers have, but not my vintage Hickok yet). They have enabled me to return duds, non matched pairs, and micro-phonic input tubes, with little or no argument from the seller. Almost 1 out of 3 sets of vintage tubes I buy have problems or are not as advertised, not too mention I can buy single tubes and match them myself. I prefer the term vintage when talking about older tubes, I feel "NOS" (New Old Stock) is grossly over used and misleading. Very few old tubes are actually untouched and mint...

In the end it's up to you. The world of tubes is very murky, but oh so rewarding :evil:

Thanks JK-47! Is there one modern tube tester you would recommend?

 

[catcherfly]

Hmmm... a reliable ebay seller... that can be a tough one. Originally I looked at buying tubes in a few ways; pay a premium and buy from a few online retailers that claim they test and match etc. , roll the dice on ebay, buy a tube tester or testers and know 100%  that I was getting what I was paying for. In some case I have had to send replacement tubes back to the seller, and have heard almost every excuse in the book.

I will say that my testers have already almost paid for themselves in the span of less than a year (my 2 new testers have, but not my vintage Hickok yet). They have enabled me to return duds, non matched pairs, and micro-phonic input tubes, with little or no argument from the seller. Almost 1 out of 3 sets of vintage tubes I buy have problems or are not as advertised, not too mention I can buy single tubes and match them myself. I prefer the term vintage when talking about older tubes, I feel "NOS" (New Old Stock) is grossly over used and misleading. Very few old tubes are actually untouched and mint...

In the end it's up to you. The world of tubes is very murky, but oh so rewarding :evil:

Victor recommended the Genalex Gold Lion KT88 as an affordable new option. Does anyone have experience with this tube? The Tube Store is one source. Have any of you purchased from them?

 

[mhamel]

Victor recommended the Genalex Gold Lion KT88 as an affordable new option. Does anyone have experience with this tube? The Tube Store is one source. Have any of you purchased from them?

 
I've been running the new release Genalex Gold Lion KT77 the past couple of months and have been really happy with them. Jim McShane sells them at a good price with a great warranty.
 
I'm using Sylvania 12BH7 as the input tubes, but the heater circuit for the preamp tubes in my amp has been upgraded to handle the additional current these draw.

 

[JK-47]

For testers I use a Maxi-Pre Amp 2, and a Maxi-matcher 2. Be warned though, the measurments will not coincide with Hickok testers that are used by many sellers on eBay. I use Hickok tested bogey tubes to create a reference for my testers.

The Amplitrex is another reference tester that many eBay sellers use. It cost more than the Maxi products, and has a may not be in Stock.

Space tech makes a few digital testers, but have not heard anything regarding their performance.

I like my Maxi's, they are awesome for matching and telling me if a tubes are bad.

In the end it doesn't seem there is one end all, be all answer to tube testers. Each one has there pros and cons...

 

[catcherfly]

For testers I use a Maxi-Pre Amp 2, and a Maxi-matcher 2. Be warned though, the measurments will not coincide with Hickok testers that are used by many sellers on eBay. I use Hickok tested bogey tubes to create a reference for my testers.

The Amplitrex is another reference tester that many eBay sellers use. It cost more than the Maxi products, and has a may not be in Stock.

Space tech makes a few digital testers, but have not heard anything regarding their performance.

I like my Maxi's, they are awesome for matching and telling me if a tubes are bad.

In the end it doesn't seem there is one end all, be all answer to tube testers. Each one has there pros and cons...

Thanks JK-47! I look forward to checking out the Maxi's and the others you mentioned