In My tube amps the power switch, swithes on the filaments and the ht.
But I switch off a separate switch for ht till the tubes warm up for abour one to five minutes.
Then I switch on ht for once again two to three minutes.
Then once the tubes are hot only I apply music.
This is a must for power amps.
For pre's the same sequence but short time should be ok.
Do this and you will be listening to your tube stuff with beautiful sound frome the start and for long years to come.
Srian.
But I switch off a separate switch for ht till the tubes warm up for abour one to five minutes.
Then I switch on ht for once again two to three minutes.
Then once the tubes are hot only I apply music.
This is a must for power amps.
For pre's the same sequence but short time should be ok.
Do this and you will be listening to your tube stuff with beautiful sound frome the start and for long years to come.
Srian.
I always use separate fliament supplies. So 2 switches.
Frankly, I rarely turn the hi-fi off. All my computer programmes go through it, which includes all my music. I'm totally digital.
Since my system consists of 4P1Ls and 01As and I have a plentiful supply of both, I'm really not bothered. I turn it off if I'm going away.
Frankly, I rarely turn the hi-fi off. All my computer programmes go through it, which includes all my music. I'm totally digital.
Since my system consists of 4P1Ls and 01As and I have a plentiful supply of both, I'm really not bothered. I turn it off if I'm going away.
I use two switches as follows.
No matter which switch you switch on first.....filament will be on first....then the other switch will get the B+ on.....
At the sme time, no matter which switch you switch off first..... B+ will be off first.
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Thanks Guys guess we're doing this to minimise cathode stripping
but what about the tube rectifier, anyway to safe guard this as AZ 1
aren't getting any cheaper. Btw re data sheet for AZ 1, it states for
first caps max is 60uf. I'm planing to use 10uf but I notice that some
are using 8uf & I believe Andy using 0.1uf why is this so ?
Thanks
but what about the tube rectifier, anyway to safe guard this as AZ 1
aren't getting any cheaper. Btw re data sheet for AZ 1, it states for
first caps max is 60uf. I'm planing to use 10uf but I notice that some
are using 8uf & I believe Andy using 0.1uf why is this so ?
Thanks
According to the data you can use up to 60uF. It's up to you what you use below that. I was using .1uF because it's choke input. It's useful to put a tiny cap before the choke.
If you want low distortion consider starved filaments. Interesting article here
DHT with starved filaments.
At the end there's a bit on cathode stripping or in his case no sign of it.
If you want low distortion consider starved filaments. Interesting article here
DHT with starved filaments.
At the end there's a bit on cathode stripping or in his case no sign of it.
Hi Andy,
Thanks , reality is I'm building with 01A's instead of the 26.
Ale tells me that I can run the pre at 160 v. what voltage are
you running at if I may ask. I also have a pair of AZ4 which
is suppose to be the same as AZ1 accept the filament current.
Can't recall if transformer filament current is sufficient for the AZ4.
Thank again
Thanks , reality is I'm building with 01A's instead of the 26.
Ale tells me that I can run the pre at 160 v. what voltage are
you running at if I may ask. I also have a pair of AZ4 which
is suppose to be the same as AZ1 accept the filament current.
Can't recall if transformer filament current is sufficient for the AZ4.
Thank again
I thought Ale's gyrator needed just over 200v? But he'll tell you himself.
You want the mesh plate with the AZ1 or AZ11. Both fine. That's the "special" sound you're after. The solid plate is just another rectifier - nothing special.
If you are going to use choke input with the AZ1 or whatever, then you must read up on critical inductance. The 01A x 2 plus gyrator is barely going to get you to 6mA, if that.
With a 30H choke you're just about OK, maybe a 100K bleeder resistor. With a 15H choke you need a 22K bleeder resistor of about 6 watts. 10H choke needs a 12K resistor which could do with being 10W. It's all a balancing act - it's nice to have a larger value choke but the DC resistance than starts to go up with smaller chokes. Hammond 30H 157G is probably a good choice - just a 100K bleeder required at 2W, and a DC resistance of 595R.
I'd recommend choke input - smoother. And definitely polypropylene caps only. Motor run caps are fine and not expensive.
You want the mesh plate with the AZ1 or AZ11. Both fine. That's the "special" sound you're after. The solid plate is just another rectifier - nothing special.
If you are going to use choke input with the AZ1 or whatever, then you must read up on critical inductance. The 01A x 2 plus gyrator is barely going to get you to 6mA, if that.
With a 30H choke you're just about OK, maybe a 100K bleeder resistor. With a 15H choke you need a 22K bleeder resistor of about 6 watts. 10H choke needs a 12K resistor which could do with being 10W. It's all a balancing act - it's nice to have a larger value choke but the DC resistance than starts to go up with smaller chokes. Hammond 30H 157G is probably a good choice - just a 100K bleeder required at 2W, and a DC resistance of 595R.
I'd recommend choke input - smoother. And definitely polypropylene caps only. Motor run caps are fine and not expensive.
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SSHV2 contains CCS and guided shunt element. If load unable takes up current (tube heater is cold), the shunt will stabilize the output voltage.
Small DHT tube (as 01, 26...) almost insensitive to "cold" cathode, so "underheating" is not problem.
Larger ones (as 10Y, 801 etc.) with thoriated tungsten filament are most sensible, even so I use my 10/801 preamp also with "one switch".
Naturally my 841-10Y-801a PSE amp has two -heaters and HV- switches (I use mercury vapor rectifiers with 10-30 min heating period).
Small DHT tube (as 01, 26...) almost insensitive to "cold" cathode, so "underheating" is not problem.
Larger ones (as 10Y, 801 etc.) with thoriated tungsten filament are most sensible, even so I use my 10/801 preamp also with "one switch".
Naturally my 841-10Y-801a PSE amp has two -heaters and HV- switches (I use mercury vapor rectifiers with 10-30 min heating period).
Hi Andy
Well I actually bought 6 rectifiers 2 AZ 1 mesh, 2 Az 1 normal
for testing purpose. The 2 Az 4 are also mesh plates.
Well if I go choke input I would need a new transformer.
What is the HV on your transformer is it 250v ?
For chokes I'm going to use 3, first choke 10H then split
to 30H hammond chokes for each channel
Thanks again for the advice
Well I actually bought 6 rectifiers 2 AZ 1 mesh, 2 Az 1 normal
for testing purpose. The 2 Az 4 are also mesh plates.
Well if I go choke input I would need a new transformer.
What is the HV on your transformer is it 250v ?
For chokes I'm going to use 3, first choke 10H then split
to 30H hammond chokes for each channel
Thanks again for the advice
Why not? That's what I did before I started building ( 380 pages for me, that's 3800 posts!). A lot of my questions were answered before I asked them.
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I agree, 438 pages is too much and a lot of it is just asking fairly trivial questions. The best site for all this is bartola valves. Ale Moglia has the best circuits these days, and this is the latest, using the latest version of his Gyrator:
VT-25 DHT Preamp Update – Bartola Valves
This circuit can be adapted for 01A or 26. Take your choice. Buy the Gyrator from Ale and ask him to give you the details for your choice of tube.
Then buy a couple of V7 filament regs from Rod Coleman (Lyrima) and specify the tube you are using, and that you will be using filament bias.
I use the 01A. The 10Y is expensive. Both are thoriated filaments. I'd put the 26 a trifle lower than those but still very good indeed.
To build the above you need the usual DIY skills plus you need to understand how filament bias works, and why you need a very good filament supply for it, ideally choke input. Look at the other threads on 01A.