[johnwmclean]

Adam, I'm considering something like this
http://www.designnotes.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=M4701B&Category_Code=hiehp
I'm not too concerned about soft start, but definitely would want protection from going to a one rail fault.

 

[jdkJake]

This looks interesting as a potential solution. A bit pricey though.
 
   http://www.borbelyaudio.com/eb292132.asp

 

[johnwmclean]

Yeah they are a bit pricey, I'll also need two as the psu is dual mono. The circuit I've referenced although not relay or soft start protecting should kick in if there's a gross error with the amp, it's also its passive. The thing I'm unsure is how this would effect sq.

 

[jdkJake]

Yeah, I hear you on the sq question. The less in the signal path the better.
 
Well, at least they are not too expensive if it does not work out.

 

[fishski13]

Quote:

Adam, I'm considering something like this
http://www.designnotes.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=M4701B&Category_Code=hiehp
I'm not too concerned about soft start, but definitely would want protection from going to a one rail fault.

i would go with the K4700 - the relay trips at 1V DC vs 10V of the K4701.  they're big and expensive.  i was researching for DC protection in an old Harman Kardon Citation 12 amp i picked up.  i don't trust 40 yr old sand running into my speakers.  i've decided to gut and rebuild it with new components.
 
Fostex has also discontinued quite a few of their drivers recently.  i would nab up a second pair for you Horn Shoppes if the drivers are on the cutting block.
 

 

[cfcubed]

BTW, Ed's great about support for his stuff.  Before I knew to *always* check DC offset, an inexpensive commercial tube pre w/o delay or offset protection used the nice DC amping of my DIY F1 to fry the FE126s in my horns.  IIRC Ed shipped out matched/treated driver replacements for less than I could get raw/unmatched drivers for.   
I now have a better pre w/relay but have yet to add speaker protection... I'd probably just grab "speaker protection" from e bay if I did it.
Quote:

<snip>
Fostex has also discontinued quite a few of their drivers recently.  i would nab up a second pair for you Horn Shoppes if the drivers are on the cutting block.

 

[rx7mark]

 
Quote:

 
Would you mind summarizing the details of the build, gains, upgrades, transformers, rev to the BOM, etc. 
 
I know some of it is on this thread, but a summary post would be great.
 
 

 
Just a reminder John, if you wouldn't mind posting the data on you build when you have a moment.
 
Ignore this if you are still camping.
 
Mark 


 

 

[johnwmclean]

Besides these components listed everything else was exactly
as per the BOM on the Cavalli Audio site. Most if not all the components
necessary for the power amp option follow are as per recommended under Tweaks.
 
My Power Amp Recipe:
 
R21 50Ω
[size=medium][size=14.0px]R13 1.82kΩ
R22, R23 33.2kΩ
C2, C3 2.2p 250V
R20 330Ω
R32, R33 5W .47Ω Mills MRA-5[/size][/size]
 
[size=medium][size=14.0px]Tubes: Telefunken white diamond ECC86.

Zobel: 22Ω 2W and 0.047µF 100V film capacitor.[/size][/size] 

[size=medium][size=14.0px]The Conrad sinks I used were custom made, so I’m not sure of any thermal spec,[/size][/size]
[size=medium][size=14.0px]they only ever get warmish, the boards are biased at 200mA.

The gain is slightly too high for the HD800, I would have preferred more travel on[/size][/size]
[size=medium][size=14.0px]the pot especially as it’s a 24 stepper (Dact). It’s also too low for inefficient speakers,[/size][/size]
[size=medium][size=14.0px]as I’ll be using Horns it won’t be an issue. Perfect for K1000’s.[/size][/size]
 
 

 

[rx7mark]

Thanks John!  
 
That is exactly what I was hoping for.  What are the specs for your transformers and what are you using for the tube heaters?
 
And any more listening impressions?   B22 comparison?
 
I am very envious and inspired, and hope to build something similar when I get back to the states.  Currently on a job in Italy.
 
Mark

 

[johnwmclean]

The tube heater is a Sigma11, configured for 12.6V output, using a Sumr 60VA 15V (single secondary) custom transformer. Be careful with the Sigma11 it’s not the best idea as a heater supply, running continuous highish current is not really what this linear supply was intended for. The temp with 6GM8 is around 45 degrees and with the 6H30’s runs hot, I’ve clocked them at 65 degrees. I’ve used the chunkiest on board http://au.element14.com/jsp/search/productdetail.jsp?SKU=1213475     
 
The psu is a dual Sigma22, Custom, SumR 120VA transformers, surprisingly even with these big Conrad heatsink’s it also gets warm.
 

 
 

 

[martinz]

Quote:

The tube heater is a Sigma11, configured for 12.6V output, using a Sumr 60VA 15V (single secondary) custom transformer. Be careful with the Sigma11 it’s not the best idea as a heater supply, running continuous highish current is not really what this linear supply was intended for. The temp with 6GMA is around 45 degrees and with the 6H30’s runs hot, I’ve clocked them at 65 degrees. I’ve used the chunkiest on board http://au.element14.com/jsp/search/productdetail.jsp?SKU=1213475     
 
The psu is a dual Sigma22, Custom, SumR 120VA transformers, surprisingly even with these big Conrad heatsink’s it also gets warm.
 

so what is the best heater for EHHA?
 

 

[johnwmclean]

I don't think there's any such thing as best just different, but I do like the H-PS-1:
http://glass-ware.stores.yahoo.net/hps1.html

There's also Pete Millets supply:
http://www.pmillett.com/DC_filament_supply.htm

The Sigma11's fine for 6MG8's, it's overkill, pricey and runs hot, but not excessively, still well within spec.

 

[martinz]

Quote:

I don't think there's any such thing as best just different, but I do like the H-PS-1:
http://glass-ware.stores.yahoo.net/hps1.html

There's also Pete Millets supply:
http://www.pmillett.com/DC_filament_supply.htm

The Sigma11's fine for 6MG8's, it's overkill, pricey and runs hot, but not excessively, still well within spec

 
I'm planning to use AC 12.6V regulator scheme from cavalli's website
 
Are those two (pete millets' & H-PS-1) a lot better than this one?

 

[sachu]

Not particularly..the one on AC's website is just perfect for the amp. I have used this in two of my EHHA builds.

 

[martinz]

thank you sachu
 
is it better using its own transformer or sharing with S22? I'm using Avel Lindberg 100VA transformer for my S22