Opinions on the web vary but most have the output of the Ipod at (or less than) 1V RMS. That's probably less than half what you'd see from just about any commercial CD player and might go a long way towards your perceived low output. But it also might not explain it. It'd be nice to know what the rated efficiency of your speaker is. My 2 way bookshelf speakers are ~90dB/1W/1M, I'm hoping the simple is more than up to the task of driving them.
Ok, all three of the following devices produce the same maximum volume on the amp:
Computer Line Out
iPod
Standalone DVD Player stolen from guest room TV
The sound quality is very good just not loud. I have no clue on the speaker specs. These were purchased from Radio Shack for $15 when they discontinued them about 2 years ago. I don't think they are very efficient. Although a picture doesn't mean much in this case, here is what it looks like:
I'm an audio newb, I don't have any other speakers yet. I was going to start working on the speakers next if the amp worked out. Nate, can me and my amp come visit sometime?
Computer Line Out
iPod
Standalone DVD Player stolen from guest room TV
The sound quality is very good just not loud. I have no clue on the speaker specs. These were purchased from Radio Shack for $15 when they discontinued them about 2 years ago. I don't think they are very efficient. Although a picture doesn't mean much in this case, here is what it looks like:
An externally hosted image should be here but it was not working when we last tested it.
I'm an audio newb, I don't have any other speakers yet. I was going to start working on the speakers next if the amp worked out. Nate, can me and my amp come visit sometime?
The Simple SE which I built is very sensitive. In other words, it has a lot of gain. Mine requires very little input voltage to drive it to ear splitting levels. My complaint was that I can never get the volume knob past 9:00 without being too loud. My speakers are rated about 92 dB.
With that said, I've experienced big changes in amplifier gain by changing the output transformers. I used a pair of 6.6K:4 ohm transformers (Hammond 1620) on a PP EL84 amp. Swapping out those transformers for a set of Z565 replicas resulted in a big drop in gain. I had to turn the volume knob up a lot more to get the same kind of volume. I think the Z565 replicas are closer to 8K~9K on the primary side for the same 4 ohm secondary load.
You could also probably get more volume simply by switching to the next size secondary tap, if you transformer has them. For example, the 8 ohm tap should be louder than the 4 ohm tap. My Simple SE has Transcendar 5K:8 transformers, and they only have the 8K tap on the secondary.
Which CXSE did you purchase? If you have the cathode feedback connected, it should get louder if you disconnect it. If you haven't hooked up the UL tap, it should be louder in UL mode (although you may want cathode feedback if you are running UL).
With that said, I've experienced big changes in amplifier gain by changing the output transformers. I used a pair of 6.6K:4 ohm transformers (Hammond 1620) on a PP EL84 amp. Swapping out those transformers for a set of Z565 replicas resulted in a big drop in gain. I had to turn the volume knob up a lot more to get the same kind of volume. I think the Z565 replicas are closer to 8K~9K on the primary side for the same 4 ohm secondary load.
You could also probably get more volume simply by switching to the next size secondary tap, if you transformer has them. For example, the 8 ohm tap should be louder than the 4 ohm tap. My Simple SE has Transcendar 5K:8 transformers, and they only have the 8K tap on the secondary.
Which CXSE did you purchase? If you have the cathode feedback connected, it should get louder if you disconnect it. If you haven't hooked up the UL tap, it should be louder in UL mode (although you may want cathode feedback if you are running UL).
n_maher said:Perhaps it's time for a picture of how you have the output trafos wired? Don't be shy, I can pretty much guarantee I've done something dumber as a part of a build.
Here you go. I just switched to UL mode to see if it made much of a difference but not really. It might be a little bit louder but nothing really noticeable.
The red wire is B+, Blue is the Plate, White/Blue is UL tap.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
It seems odd that an EH tube would have no markings at all. Most of the EH I've seen have a relatively boring font in black print. Got a pic of your tube, by any chance?
Well, now I'm a liar. This one has yellow print.
http://www.newsensor.com/ProductHighLight.aspx?ProId=24
and this one:
http://thetubestore.com/12at7eh.html
and this one too:
http://www.tubedepot.com/eh-12at7.html
Well, now I'm a liar. This one has yellow print.
http://www.newsensor.com/ProductHighLight.aspx?ProId=24
and this one:
http://thetubestore.com/12at7eh.html
and this one too:
http://www.tubedepot.com/eh-12at7.html
Definitely Russian. I can see the flying saucer. The plates look about the right shape and size too, although that isn't conclusive. I'd wager it probably is a 12AT7, although it's still odd there is no printing on it. OK, maybe not so odd. My New Sensor KT88 have no printing on them either.
Have you triple checked the values of all the resistors installed on the board? There's only a couple dozen - it doesn't take long to go through them all with the ohmmeter. Keep the power off, obviously.
What's the primary impedance of your CXSE? Did you get the CXSE25-8-5K?
Have you triple checked the values of all the resistors installed on the board? There's only a couple dozen - it doesn't take long to go through them all with the ohmmeter. Keep the power off, obviously.
What's the primary impedance of your CXSE? Did you get the CXSE25-8-5K?
I cannot see any errors with the way the transformers are wired. Do you have access to a different 12AT7 input valve? You might find one at a music shop that sells guitar amps. Otherwise, I would pull the board out and check ALL of the component values on the board. You may have mixed up some of the resistors. Check with a meter. Not the first time I have made that mistake. My electronics knowledge is not that great, but what would the effect be of a burnt out current regulator?
Best of luck...
Best of luck...
chrish said:
Ha ha! It's half past eleven here... nearly midnight! But lunch does sound good. I wonder what's upstairs in the fridge?
As long as you keep at least 0.5 mA through the 12AT7, the gain doesn't change much and it should be reasonably linear. Overall amp gain should be from about 16.5 dB (0.5 mA) to 19.5 dB (10 mA) with a healthy 12AT7. Once the CCS falls under ~0.4 mA it turns to garbage. Frequency response goes in the toilet and amp gain is -50 dB. It just won't work at all.
N1ESE said:All resistors check out A-OK so that's not it.
Donut have another 12AT7 to try at the moment.
I can test a few of the dozen or so that I have and drop a few in the mail to you Monday. Or if you're dying to get the thing running we might be able to hook up some time this weekend. Drop an email with your address at a minimum.
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