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Skorpio 27th November 2009 10:19 AM

Tubelab Simple SE questions
 
Hi,

I am in the process of building Tubelabs Simple SE amplifier. Most of the components are on hand and only few things must be cleared:

Due to layout issues, I have two seperate ECC81 tubes, one on each side of chassis. I would like to try different input possibilities:

1.SRPP
2.CCS loading as standard
3.CCS loading with other half of ECC81

How do I connect a ECC81 as CCS (10mA) and what values do I use?
Is there any problems with this compared with the standard solid state CCS?

Is it possible to change from UL to triode mode and from feedback to non-feedback during playback?

hwong 11th December 2009 01:31 AM

I have started building the Simple SE but everything is in limbo for almost 4 weeks.

Most of the parts are ordered from Digikey (Canada). R2, C10, C20, C12, C22 and the Hammond choke from Mouser because Digikey does not have any in stock. Put the orders in on the same day, got my Digikey order 2 days after (Nov-12) but am still waiting for the Mouser order to arrive!

Talked to Mouser yesterday and the guy told me it will take up to 10 weeks because USPS is not very reliable lately! (I have no problem with USPS with other US online retailer). Anyway, I found a Candian online outfit that carries the caps but they do not have the Metal Oxide R2. This is what they have,
VISHAY BC COMPONENTS|PR03000201503JAC00|Metal Film Resistor | Newark.com

will it be fine to use this instead?

rotaspec 11th December 2009 01:48 AM

Quote:

Originally Posted by hwong (Post 2009330)
I have started building the Simple SE but everything is in limbo for almost 4 weeks.

Talked to Mouser yesterday and the guy told me it will take up to 10 weeks because USPS is not very reliable lately! (I have no problem with USPS with other US online retailer). Anyway, I found a Candian online outfit that carries the caps but they do not have the Metal Oxide R2. This is what they have,
VISHAY BC COMPONENTS|PR03000201503JAC00|Metal Film Resistor | Newark.com

will it be fine to use this instead?

I don't have the circuit schematic here, but you should be fine as the value and rating are the same. You can always change to the original later if needed.

Gary

tubelab.com 11th December 2009 01:53 AM

Quote:

will it be fine to use this instead?
It will work fine. R2 is just a bleeder resistor to make sure that the power supply caps get discharged when the power is shut off. These new small size resistors get pretty hot so make sure that it is not placed in direct contact with the PC board. Leave 1/4 to 1/2 inch of space between them.

hwong 11th December 2009 04:54 AM

Great. Thanks. Will put the order in and should get them within 2 days. Then I can complete the build.

hwong 15th December 2009 04:18 PM

Need more help here.

I recevied the resistor and capacitors 2 days after I put the order in. That was fast services. Fellow canadian if you are looking for an alternative online supplier, try this outfit US - Electronic Components Distributor | Newark.com.

I made a mistake when ordering the 6.3V cap. Somehow I put in 15000uF instead of the 1500uf. I found out when I try to insert it into the pcb and the leads spacing don't line up properly. So I have to order them again. This is when the question came up:
The Didgikey part list in tubelab is a panasonic FC and the Mouser part is a Nichicon, the Newark carries United Chemi-Con. I got the 1500uf 63V and they have the 6.3V also.

UNITED CHEMI-CON|EKZE6R3ELL152MJ20S|Aluminum Electrolytic Capacitor | Newark.com

The spec looked the same but if I deviate away from these two brand, will it affect the quality of the sound?

I can order from Digikey but they don't have the FC series in stock. They do have the FM series (Part P-12343-ND). Is it not as good as the FC series and that is why it did not make it to the tubelab partlist?

Will the FM series better than the United Chemi-Con? Since both Digikey and Newark have the canadian arm, their delivery time is usually within 2 working days.

I have given up hope on my Mouser order, still no sight of it after six weeks. How long will it take to ship a <3lb package from TX to Canada? Is this an issue with Mouser or is it USPS ** Sigh**

MellowTone 16th December 2009 12:16 AM

Quote:

Originally Posted by Skorpio (Post 1994268)
Due to layout issues, I have two seperate ECC81 tubes, one on each side of chassis.

Sorry, can you explain exactly what you mean by that?

Quote:

Originally Posted by Skorpio (Post 1994268)
Is it possible to change from UL to triode mode and from feedback to non-feedback during playback?

I'm pretty sure you'll do damage to the amp, tubes and yourself trying that. Definitely don't go switching UL to triode while going. I wouldn't try switching feedback while it's on either.

As a general rule with tubes, if you're changing anything, turn it off, unplug it, change whatever it is then check again before powering up. When you're working with expensive tubes and several hundred volts, better safe than sorry.

DigitalJunkie 16th December 2009 12:34 AM

Sometimes you can get away with switching 'on the fly' but it is not recommended,It may result in loud clicks and pops,possibly damaging to speakers,if not tubes,transformers,etc.
I've done it on certain amps,but there's usually a 'thump' involved.
Unplugging the amp is a bit excessive,but turning it off before switching settings is a good idea,if not standard practice.

Skorpio 16th December 2009 10:44 AM

Quote:

Originally Posted by MellowTone (Post 2014464)
Sorry, can you explain exactly what you mean by that?



I'm pretty sure you'll do damage to the amp, tubes and yourself trying that. Definitely don't go switching UL to triode while going. I wouldn't try switching feedback while it's on either.

As a general rule with tubes, if you're changing anything, turn it off, unplug it, change whatever it is then check again before powering up. When you're working with expensive tubes and several hundred volts, better safe than sorry.

Instead of one common ECC81 (one half for each channel) I am using two seperate ECC81, one for each channel with one half left unused...

Ty_Bower 16th December 2009 11:43 AM

Quote:

Originally Posted by hwong (Post 2013966)
I made a mistake when ordering the 6.3V cap. Somehow I put in 15000uF instead of the 1500uf. I found out when I try to insert it into the pcb and the leads spacing don't line up properly.

This is somewhat off topic, but anyway...

When you install the electrolytic capacitors, don't have them tight up against the board when you solder them in. Leave a small (1/16" ~ 1/8") gap between the bottom of the cap and the circuit board.

George makes a passing mention of this somewhere in the assembly instructions. If you keep them tight against the board, then each time they expand/contract from thermal cycles, they pull at the leads. Eventually it can cause early failure of the cap. Leaving just a tiny wiggle room here eliminates this problem.


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