Hi Brinkman,
The 5 V is nothing. Also consider that the larger core and higher quality steel lowers the flux density, making a quieter transformer. Over sizing the power transformer is always a good practice in tube gear. So buying exactly what you think you need, you may be shooting yourself in the foot. Within reason of course!
-Chris
The 5 V is nothing. Also consider that the larger core and higher quality steel lowers the flux density, making a quieter transformer. Over sizing the power transformer is always a good practice in tube gear. So buying exactly what you think you need, you may be shooting yourself in the foot. Within reason of course!
-Chris
The specified TX from the impasse article is: 325-0-325V @ 40mA; 6.3VCT @ 2.0A
The Hammond 290CX is 325-0-50-325V @ 207mA; 5V @ 3A; 6.3VCT @4.5A and weighs 6.8lbs. Prices range from $80-100USD before shipping.
The Edcor XPWR051 is 330-0-330V @ 125mA; 6.3VCT @ 4.0A and weighs 6.0lbs. Price is $61.91USD before shipping.
The Edcor XPWR268 is 325-0-325V @ 150mA; 6.3VCT @ 4.5A and also weighs 6.0lbs. Price is $62.42USD before shipping.
I decided to set the Hammond aside for use with my Tubelab SE (which will actually utilize the 5V winding) and ordered the XPWR268 because its VA rating was higher than the XPWR051.
The Hammond 290CX is 325-0-50-325V @ 207mA; 5V @ 3A; 6.3VCT @4.5A and weighs 6.8lbs. Prices range from $80-100USD before shipping.
The Edcor XPWR051 is 330-0-330V @ 125mA; 6.3VCT @ 4.0A and weighs 6.0lbs. Price is $61.91USD before shipping.
The Edcor XPWR268 is 325-0-325V @ 150mA; 6.3VCT @ 4.5A and also weighs 6.0lbs. Price is $62.42USD before shipping.
I decided to set the Hammond aside for use with my Tubelab SE (which will actually utilize the 5V winding) and ordered the XPWR268 because its VA rating was higher than the XPWR051.
Great to hear that. The B+ of the Hammond is a bit high for my intended use of 45 tubes but I would like to change the power supply of my Tubelab SE to choke-input and hopefully that will eat up some of the surplus B+. Otherwise, the Edcor I selected seems sufficiently overspec’d for the Impasse.
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Don't be too concerned about the higher B+. It won't hurt you. Back in the days of tubes, voltages were easily 20% from the stated value, and the test equipment they used wasn't a whole lot better. B+ measurements might have been 5%, but the AC supply varied a lot more than that. Your Edcor will be fine.
Too bad you're using 45 tubes. I use them for restoring old radios because I have no choice as to what I have to use. Designing new equipment to use old tubes no longer manufactured puts excessive pressure on existing stock and drives the prices up on the poor person who wants their old radio to work. If you have a choice in the future, please choose tubes that are in current production.
"No snowflake in an avalanche ever feels responsible"
-Chris
Too bad you're using 45 tubes. I use them for restoring old radios because I have no choice as to what I have to use. Designing new equipment to use old tubes no longer manufactured puts excessive pressure on existing stock and drives the prices up on the poor person who wants their old radio to work. If you have a choice in the future, please choose tubes that are in current production.
"No snowflake in an avalanche ever feels responsible"
-Chris
I see your point which is why the Tubelab project is the only one I have planned that uses no longer in production tubes. I don’t like to build projects that I cannot hand down because I chose to build it using esoteric/expensive/NLA tubes. This is why my other tube projects use KT88s, EL34 or new-production 300B (gold lion).
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I would think that's ok.
They're specified as ceramic discs. Not sure why they have to be rated so high voltage. Maybe good practice incase of catastrophic tube failure or something. I think there's about 60v on the centre tap with a fairly low ac current on the heaters.
The purpose of these caps is to remove high frequency noise.
0.01uf (10nf) is pretty small, so 0.047 would mean it would filter a bit lower.
A quick Google suggests the typical working resistance of a heater element is 80ohms,so
Cutoff freq = 1/(2pi*rc) which for 80 ohms and 0.00000001f is about 200khz.
If for three heaters in parallel, say 20ohm then your 0.047uf would have a cutoff around 170khz.
I see no reason why, value wise 0.047 would be an issue.
Is it ceramic caps you have of this value?
I can't see any reason why film shouldn't be used. I'm guessing that cost would be the most likely reason.
They have the voltage rating required and x or y caps havnt been specified here.
They're specified as ceramic discs. Not sure why they have to be rated so high voltage. Maybe good practice incase of catastrophic tube failure or something. I think there's about 60v on the centre tap with a fairly low ac current on the heaters.
The purpose of these caps is to remove high frequency noise.
0.01uf (10nf) is pretty small, so 0.047 would mean it would filter a bit lower.
A quick Google suggests the typical working resistance of a heater element is 80ohms,so
Cutoff freq = 1/(2pi*rc) which for 80 ohms and 0.00000001f is about 200khz.
If for three heaters in parallel, say 20ohm then your 0.047uf would have a cutoff around 170khz.
I see no reason why, value wise 0.047 would be an issue.
Is it ceramic caps you have of this value?
I can't see any reason why film shouldn't be used. I'm guessing that cost would be the most likely reason.
They have the voltage rating required and x or y caps havnt been specified here.
Thanks for the input. I have film caps, but I, too, can't find a reason film won't work. I'm just trying to avoid a mail order for nothing but a couple of caps.
Finally got my Edcor XPWR268-120 power transformer for my imPasse today.
@MrDave45: I see you have the F4 plus imPasse as well as the His Masters Noise phono preamp? I’m planning on building a MC version of Sy’s Equal Opportunity phono preamp; would you care to comment on the sound of the HMN + Impasse + F4 combo?
@MrDave45: I see you have the F4 plus imPasse as well as the His Masters Noise phono preamp? I’m planning on building a MC version of Sy’s Equal Opportunity phono preamp; would you care to comment on the sound of the HMN + Impasse + F4 combo?
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@Brinkman
Hi, I've used the posh sowter step ups in my hmn, it's been loaded to suit a benz wood sl (0.3mv), although sowter recommended just using a 47k l I adding resistor, but with experimentation I settled on some zobel network.
The system has no hiss at usual listening levels (say one o'clock on preamp) , only once you get to around 4 o'clock or so.
Provided you have a good slab, preferably a tape recording, then certainly in combination with the obl15 recordings sound like instruments rather than recordings of instruments.
My local hifi dealer usually has some kef blade 2 or reference hooked up to chord Dave through expensive chord or musical fidelity integrated amps.
Their setup has better trble and stereo imaging, mine has better bass, mid range and tonality.
As long as you partner this system with reasonably sensitive speakers, I really don't think you would be disappointed. Apart from better dacs and streamers, my next upgrade would be a second f4 to either run bridged or biamp. I have no desire to improve speakers or amplifiers otherwise. I always get the feeling this is what it must have sounded like in the control room. It's just sounds right.
Hi, I've used the posh sowter step ups in my hmn, it's been loaded to suit a benz wood sl (0.3mv), although sowter recommended just using a 47k l I adding resistor, but with experimentation I settled on some zobel network.
The system has no hiss at usual listening levels (say one o'clock on preamp) , only once you get to around 4 o'clock or so.
Provided you have a good slab, preferably a tape recording, then certainly in combination with the obl15 recordings sound like instruments rather than recordings of instruments.
My local hifi dealer usually has some kef blade 2 or reference hooked up to chord Dave through expensive chord or musical fidelity integrated amps.
Their setup has better trble and stereo imaging, mine has better bass, mid range and tonality.
As long as you partner this system with reasonably sensitive speakers, I really don't think you would be disappointed. Apart from better dacs and streamers, my next upgrade would be a second f4 to either run bridged or biamp. I have no desire to improve speakers or amplifiers otherwise. I always get the feeling this is what it must have sounded like in the control room. It's just sounds right.
Has anyone added a line out to the impasse?
Id quite like to add one to send to my headphone amp, and maybe a sub later on, but there are other options for that.
Id rather avoid using opamps if possible. Probably slightly irrational, but i dont think the HMN, impasse or f4 use negative feedback. Not sure about my headphone amp though.... Its a g&w T2.6F hybrid. I recently picked up a second one on ebay for a steal for use with my main hifi. Ive used my first one in my studio for the last 15 years or so and i still love it.
Id quite like to add one to send to my headphone amp, and maybe a sub later on, but there are other options for that.
Id rather avoid using opamps if possible. Probably slightly irrational, but i dont think the HMN, impasse or f4 use negative feedback. Not sure about my headphone amp though.... Its a g&w T2.6F hybrid. I recently picked up a second one on ebay for a steal for use with my main hifi. Ive used my first one in my studio for the last 15 years or so and i still love it.
