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McChanson Valve Amp Owners Thread


BLAH BLAH

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I have query, if anyone can help. I'm running a McChanson headphone amp/tube buffer as a preamp.

 

The McChanson uses different tubes to most preamps -

1 x 6V4/6BW4 and

2 x 6S45P/ 6S15P

 

Are there equivalent tubes to these that will do the job? I think the 6S45P is the same as the EC8020 and WE437A, but I don't want to roll the wrong tubes and do damage.

 

The 6V4 is the one I can't find an equivalent for. The current tube I am using is a GE, which came with the headphone amp - but the details on it are too faded to read. 

 

Any advice is welcome.

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1 hour ago, Gelert said:

I have query, if anyone can help. I'm running a McChanson headphone amp/tube buffer as a preamp.

 

The McChanson uses different tubes to most preamps -

1 x 6V4/6BW4 and

2 x 6S45P/ 6S15P

 

Are there equivalent tubes to these that will do the job? I think the 6S45P is the same as the EC8020 and WE437A, but I don't want to roll the wrong tubes and do damage.

 

The 6V4 is the one I can't find an equivalent for. The current tube I am using is a GE, which came with the headphone amp - but the details on it are too faded to read. 

 

Any advice is welcome.

Email Eric and ask him, I am sure he will tell you what you can use.

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2 hours ago, Gelert said:

I have query, if anyone can help. I'm running a McChanson headphone amp/tube buffer as a preamp.

 

The McChanson uses different tubes to most preamps -

1 x 6V4/6BW4 and

2 x 6S45P/ 6S15P

 

Are there equivalent tubes to these that will do the job? I think the 6S45P is the same as the EC8020 and WE437A, but I don't want to roll the wrong tubes and do damage.

 

The 6V4 is the one I can't find an equivalent for. The current tube I am using is a GE, which came with the headphone amp - but the details on it are too faded to read. 

 

Any advice is welcome.


I don’t know anything about 6V4, however my McChanson headphone amp also uses 6BW4 as rectifier tube.

I did some research and as a backup, if I cannot source any NOS 6BW4, I believe I can tube roll to EZ81 or 6CA4 or EZ80, despite some of these alternatives having more current capacities (runs hotter or less hot?)

 

Regardless, I have since found very affordable GE NOS 6BW4 on fleabay.  My understanding is that rectifier tubes don’t need replacing as often as power tube, so I haven’t really gone crazy to stock up, only got 2 spare. 
 

Best bet is still to email Eric for details. 

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On 14/10/2021 at 11:44 AM, BLAH BLAH said:

Yes but would it make a difference to the sound output though...:hyper:

Based on my careful tests during integration of each component into the signal chain, yes I do believe that the current (unconventional) signal chain collectively provides the most enjoyable tonal character (to my ears) across all media types within my particular room size and configuration. In the spirit of ongoing system development, rearranged the chain so that the analogue signal from Meridian 568.2mm no longer goes through Sansui AU-777A preamp stage but rather goes directly into Phase Linear 1000 autocorrelator. Haven't begun listening tests yet but am curious to see if the benefit noticed upon adding the Sansui into the chain as a preamp (now just serves as phono stage) is noticeably lost upon its removal from the chain. It might not be as I was not previously using the Phase Linear 1000 for post-DAC processing but now that I am, this might overshadow the "toobiness" colouration added by Sansui preamp stage as the AU-777A, to my understanding, is their first non-tube flagship model and was thus designed to sound like a tube amp but without the tubes. Will report back on in situ test results :thumb:

 

On 14/10/2021 at 11:54 AM, lenticularis said:

Would it act like a bass-trap?

Not sure what exactly you are referring to, but the low end in my system sounds so sweet that people wander in off the street like flies to sh*t, which I suppose could be described as a "bass trap" 🤣

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1 hour ago, att23 said:

I did some research and as a backup, if I cannot source any NOS 6BW4, I believe I can tube roll to EZ81 or 6CA4 or EZ80, despite some of these alternatives having more current capacities (runs hotter or less hot?)

After quite a bit of research I ended up replacing the stock 6BW4 rectifier tube with a NOS Amperex Bugle Boy EZ81 (via Etsy tube shop) given that Eric's design for this unit permits rolling a 6BW4 for EZ81, EZ81, or 6V4. Noticeable sound improvement since making the switch. Can't say for sure if this caused an increase in heat output from unit, but maybe 🤷‍♂️

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@krazywaffle I actually couldn’t hear any difference even when I accidentally plugged the 12AT7 in lieu of the 6BW4 :P
 

I can only hear difference when I tube roll the power and preamp tubes. 

Edited by att23
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3 minutes ago, att23 said:

I actually couldn’t hear any difference even when I accidentally plugged the 12AT7 in lieu of the 6BW4 :P

Interesting. Didn't know that a 12AT7 could be used in lieu of the 6BW4 rectifier 🤔

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3 hours ago, krazywaffle said:

Interesting. Didn't know that a 12AT7 could be used in lieu of the 6BW4 rectifier 🤔

Probably should not try. It was a rookie mistake, but it didn’t blow up and there was no damage done. I was happily listening to a few songs before I realise the mishap, and didn’t notice any SQ issues. LOL. Perhaps testament to Eric’s robust design?

 

Edit: I made the mistake because they look quite similar (to a newbie, now I realised they don’t look alike) and the faded marking of 6201 on the NOS tube (another name for 12AT7) got me confused with 6BW4. 
 

Edited by att23
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On 12/10/2021 at 11:48 PM, xlr8or said:

 

OK - very good question. So this all depends on the input sensitivity of the integrated tube amp and what mV value is specified. What you ideally want is for the incoming signal to be capped at this value in order for it to not clip and distort the amplified signal at the maximum volume output of the tube amp.

 

So what should you do? Maximise the preamp volume or the integrated amp volume? Think of the intergrated amp serving as a power amp without the volume control. In this case turn up the volume on the intergrated amp to its maximum setting and use the preamp volume control to feed in the signal volume level. That's how I would recommend doing it. I would even go as far and recommend you bypass the volume control on the intergrated amp and shunt it with a 50kohm resistor to remove it from the signal path. Easy enough to do if you're OK to use a soldering iron. You can always return it back to its default configuration.


Thank you Kirk,

 

Having assembled my own light-dependant resistor Stereo Coffee pre-@amp from the basic circuit-board kit and loving its transparency, I continue to use it as a pre-amp into my TimE KT 150 amp from Eric.

 

Thinking I was ‘kinder’ to the load for the Valve amp to drive my 87dB efficient speakers, I had the pre-amp at max and the KT150 at whatever level I wanted for my chosen volume level.

 

Following your post, I now have the KT150 at max. volume setting and the pre-amp modulating. It seems I get a richer sound this way, more akin to my big 200wpc solid-state amp, but retaining the sweetness of valves.

 

 

Edited by lenticularis
Typo
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17 hours ago, att23 said:


I don’t know anything about 6V4, however my McChanson headphone amp also uses 6BW4 as rectifier tube.

I did some research and as a backup, if I cannot source any NOS 6BW4, I believe I can tube roll to EZ81 or 6CA4 or EZ80, despite some of these alternatives having more current capacities (runs hotter or less hot?)

 

Regardless, I have since found very affordable GE NOS 6BW4 on fleabay.  My understanding is that rectifier tubes don’t need replacing as often as power tube, so I haven’t really gone crazy to stock up, only got 2 spare. 
 

Best bet is still to email Eric for details. 

Thank you,

 

I had made some notes a couple of years ago when I bought the amp off Eric, just in case I wanted to try some tube rolling.

My notes bracket the 6V4 and 6BW4 as similar; so 6BW4 would be the one I would look for. I have a second GE rectifier already, so I guess I can look for a matched pair of replacement drive tubes.  

 

I know bugger all about tubes, but wanted to hear what all the fuss was about. He makes nice sounding gear, even though some of it looks basic. The build quality is excellent. 

 

I picked up the tube buffer directly from him in Burwood. He gave me some passive, non tube and non powered products to evaluate for him that he was experimenting with as buffers that might improve the sound for some systems. They were interesting, and did change the sound to a more tube like quality, but lacked the soundstage.

 

Really nice guy, Eric. 

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On 15/10/2021 at 1:44 PM, att23 said:


I don’t know anything about 6V4, however my McChanson headphone amp also uses 6BW4 as rectifier tube.

I did some research and as a backup, if I cannot source any NOS 6BW4, I believe I can tube roll to EZ81 or 6CA4 or EZ80, despite some of these alternatives having more current capacities (runs hotter or less hot?)

 

Regardless, I have since found very affordable GE NOS 6BW4 on fleabay.  My understanding is that rectifier tubes don’t need replacing as often as power tube, so I haven’t really gone crazy to stock up, only got 2 spare. 
 

Best bet is still to email Eric for details. 

I emailed Eric,

 

He doesn't know about that Svetlana tube; and recommended not to use it.

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@Gelert Not sure what you asked Eric, and why specifically Svetlana brand name pops up.  I only know EZ81 was introduced by Mullard in the 50s and nowadays most commonly manufactured by JJ electronics. So it’s in abundance as alternative.
 

So what useful alternative did Eric give you? 
 

Edit:  Here you go in case yourself or Eric wants to know more…
https://www.jj-electronic.com/en/ez81-6ca4

 

Edited by att23
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The EZ80/6V4 is different to the EZ81/6CA4 and 6BW4. The EZ80 takes in 600mA for its 6.3v heater voltage.  The EZ81 takes in 1,000mA and the 6BW4 takes in 950mA. The power transformer needs to be checked for the 6.3v seconday to ensure it has enough current capacity to accommodate the increase required from the EZ81 and 6BW4. You can always go backwards, but going forward requires checking. Why one would change a rectifier type comes back to acquiring a 'stiffer' sound. The voltage drop on the DC rectified B+ going to the tubes would be higher with the EZ80 in place compared to the EZ81. The EZ81 would technically draw in more plate current. So you maybe asking which rectifier type should I use? The one that allows the least voltage drop for a change in rectifier type.

Edited by xlr8or
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Thanks @xlr8or for clarifying.  Basically, EZ80 is equivalent to 6V4.
Whereas the fact that @Gelert mentioned in his initial post that he can also use 6BW4 (assumed this was advised by Eric) means that he now can also use EZ81 and 6CA4. 

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Just now, att23 said:

Thanks @xlr8or for clarifying.  Basically, EZ80 is equivalent to 6V4.
Whereas the fact that @Gelert mentioned in his initial post that he can also use 6BW4 (assumed this was advised by Eric) means that he now can also use EZ81 and 6CA4. 

 

Yep, along with the GEC U709, which is a priceless treasure. 😁

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6 minutes ago, xlr8or said:

 

Yep, along with the GEC U709, which is a priceless treasure. 😁


Sounds too exotic for me 😜 given I cannot tell the different rectifier sound especially via my headphones… 

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19 minutes ago, att23 said:


Sounds too exotic for me 😜 given I cannot tell the different rectifier sound especially via my headphones… 

 

The best sounding EZ80 out there is the 1950's Brimar long black shiny plate square getter. For the EZ81, it's the 1950's GEC/Marconi U709. You can hear a difference in these 2 rectifiers.

 

20211017_095516.thumb.jpg.45f7c162bffbc1cfa6a328ed1cb626c0.jpg

 

Screenshot_20211017-095629_eBay.thumb.jpg.10f69f70b66b717f9366d9cb3953a461.jpg

 

Screenshot_20211017-095651_eBay.thumb.jpg.d5d3c179acda47349f16cef1c287363b.jpg

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1 hour ago, xlr8or said:

For the EZ81, it's the 1950's GEC/Marconi U709. You can hear a difference in these 2 rectifiers

Thanks for the insight. Could tell a notable improvement when tube buffer rectifier was rolled from stock Russian 6BW4 (supplied with unit) to NOS Amperex Bugle Boy EZ81. Will keep an eye out for a GEC/Marconi U709 for next rolling round. Any suggestion for what matched pair might be worthwhile rolling current Russian 6S3P-DR gold grids for?

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2 hours ago, att23 said:

@Gelert Not sure what you asked Eric, and why specifically Svetlana brand name pops up.  I only know EZ81 was introduced by Mullard in the 50s and nowadays most commonly manufactured by JJ electronics. So it’s in abundance as alternative.
 

So what useful alternative did Eric give you? 
 

Edit:  Here you go in case yourself or Eric wants to know more…
https://www.jj-electronic.com/en/ez81-6ca4

 

Thanks for the link. Eric offered no alternative to these tubes, just said they shouldn't be tried; and suggested I email him if I needed to know more. As I was curious about the Svetlanas, I will just not use them; and stay with the GEs as rectifiers. I have a spare GE, so no need to change tubes. 

 

I'm using Reflektor 6S45P-E tubes for the output stage, and they are providing a nice sound.

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10 hours ago, krazywaffle said:

Thanks for the insight. Could tell a notable improvement when tube buffer rectifier was rolled from stock Russian 6BW4 (supplied with unit) to NOS Amperex Bugle Boy EZ81. Will keep an eye out for a GEC/Marconi U709 for next rolling round. Any suggestion for what matched pair might be worthwhile rolling current Russian 6S3P-DR gold grids for?

 

My pick for the 6S45P would be the EC8020. However, finding them is a real challenge. Here are some other substitutes for the 6S45P that can also be considered:

 

https://www.diy-audio-guide.com/6c45.html

 

For the 6S3P, my pick would be the WE 417A. Other suitable substitutes for the 6S3P are the 5842, EC86 and PC86.

Edited by xlr8or
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17 hours ago, xlr8or said:

For the 6S3P, my pick would be the WE 417A. Other suitable substitutes for the 6S3P are the 5842, EC86 and PC86.

Thanks heaps for the suggestions, will commence hunting :thumb:

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On 15/10/2021 at 2:33 PM, krazywaffle said:

Will report back on in situ test results :thumb:

The loss of "magic" was almost immediately noticeable following the removal of the Sansui AU-777A preamp stage from signal chain. As such, I'd recommend in situ experimentation with high-quality vintage preamp stages (dedicated or integrated) to assess their imposition of "magic" into the heard music :)

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