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Old 22nd November 2012, 02:50 AM   #31
freax is offline freax  Australia
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Yeah, I'll think about the OTL amp, thanks for your help guys.

Alright, I'll go with the OTL amp.

Removing those output transformers from the signal path is what convinced me that its a good idea regardless, that and the fact that I've currently got speakers that will sing just fine at 15 watts (Sony SS-212's), and that it consumes the same amount as an ST-70...

And that 10 watts tube power is enough for me, but 15 watts is even slightly better.

And I can always roll a couple of chip amps for the 12inch or 15 inch down throwing drivers.

Last edited by freax; 22nd November 2012 at 03:13 AM.
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Old 22nd November 2012, 03:15 AM   #32
cotdt is offline cotdt  United States
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What's the point of a nice amp with poor source and poor speakers? The amp makes the least amount of difference. You should upgrade the rest first and just use a chipamp for under $200.

When you have the funds, you can get a SE 845 or GM70 setup for your 20W of output. The transformers alone might cost $1000. An EL34 based amp is not going to be near as transparent as a direct-heated triode amp based on George Anderson's design.
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Old 22nd November 2012, 03:34 AM   #33
freax is offline freax  Australia
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Quote:
Originally Posted by cotdt View Post
What's the point of a nice amp with poor source and poor speakers? The amp makes the least amount of difference. You should upgrade the rest first and just use a chipamp for under $200.

When you have the funds, you can get a SE 845 or GM70 setup for your 20W of output. The transformers alone might cost $1000. An EL34 based amp is not going to be near as transparent as a direct-heated triode amp based on George Anderson's design.

I've got a nice source, its in the mail, arriving from Russia, then needs to be built.

nice, very nice: 6C33C OTL power amp running two heaters on OP tubes.. - YouTube

All I need now is good speakers.

Last edited by freax; 22nd November 2012 at 03:38 AM.
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Old 22nd November 2012, 03:35 AM   #34
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Originally Posted by freax View Post
Yeah, I'll think about the OTL amp, thanks for your help guys.

Alright, I'll go with the OTL amp.

Removing those output transformers from the signal path is what convinced me that its a good idea regardless, that and the fact that I've currently got speakers that will sing just fine at 15 watts (Sony SS-212's), and that it consumes the same amount as an ST-70...

And that 10 watts tube power is enough for me, but 15 watts is even slightly better.

And I can always roll a couple of chip amps for the 12inch or 15 inch down throwing drivers.
You might be surprised what this OTL can do, but as cotdt mentioned, the amp is not nearly as significant as the speakers first and signal source second. Once they are taken care of, the right amp can bring it all to life.

Of course if you're in the mood for an amp project, then go for it. It would be hard to beat this OTL for the $$$.

I've been wiring like a maniac all night. Time for a break.
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Old 22nd November 2012, 03:39 AM   #35
freax is offline freax  Australia
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Originally Posted by Alan Cohen View Post
You might be surprised what this OTL can do, but as cotdt mentioned, the amp is not nearly as significant as the speakers first and signal source second. Once they are taken care of, the right amp can bring it all to life.

Of course if you're in the mood for an amp project, then go for it. It would be hard to beat this OTL for the $$$.

I've been wiring like a maniac all night. Time for a break.
Indeed, its good to take a break once in a while from doing THAT many point to point joints.

You might be surprised what kind of amp I am using, a Sony STR-K670P

Click the image to open in full size.

And I have reached the limit of what this amp can do, and I'm bored with it, infact its ticking me off.

It'll be a nice upgrade I reckon

I just hope I can get the order in before the country shuts down for the year...

Last edited by freax; 22nd November 2012 at 03:54 AM.
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Old 22nd November 2012, 04:14 AM   #36
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Agreed, Freax. I've had one of these for a few years now (Sony STR-DA5600ES). It's actually great as a 7.1 processor, but for music listening, it's pretty much useless. Weak-kneed with a hard and thin sound. I can show you some $59 DACs from ebay that sound better than the one in this thing. The controls on the front panel are impossible to understand and the on-screen menus are just as bad. See that knob on the left marked "TONE"? Yeah, doesn't do what you'd expect - at all. And that's just the start...

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Old 22nd November 2012, 04:20 AM   #37
freax is offline freax  Australia
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Originally Posted by autoformer View Post
Agreed, Freax. I've had one of these for a few years now (Sony STR-DA5600ES). It's actually great as a 7.1 processor, but for music listening, it's pretty much useless.
Cheap tho, thats why I bought it, for $120 off ebay :P Mine does good as a bass driver, I might keep it hanging around to drive my 12 inch sealed sub in combination with the OTL tube amp.

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Weak-kneed with a hard and thin sound. I can show you some $59 DACs from ebay that sound better than the one in this thing.
OMG the dac is actually worse than my onboard soundcard's DAC!

This is the one that I'm working on at the moment: http://www.diyaudio.com/forums/digit...-off-ebay.html

I was surprised when I switched from using TOSLINK/optical SPDIF for 4 years over to analog rca just recently as an experiment.

I suppose back when it was made it was half decent for consumer gear, but not today, even when contending with an onboard motherboard DAC.. haha

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The controls on the front panel are impossible to understand and the on-screen menus are just as bad. See that knob on the left marked "TONE"? Yeah, doesn't do what you'd expect - at all. And that's just the start...
Yep I had another Sony here with me not that long ago with Bass + Tone controls on it, neither one did a damn thing! Weak at the knees even for a cheap integrated chip amp.

Last edited by freax; 22nd November 2012 at 04:36 AM.
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Old 22nd November 2012, 09:35 AM   #38
freax is offline freax  Australia
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Can you guys provide me a schematic? Info on this amp is eluding me.

I'm looking at their forum now.

Last edited by freax; 22nd November 2012 at 09:40 AM.
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Old 22nd November 2012, 12:41 PM   #39
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Originally Posted by freax View Post
Can you guys provide me a schematic? Info on this amp is eluding me.

I'm looking at their forum now.
Which amp? The 15W OTL? If so, the schematic is published in his book Tubes and Circuits: Bruce Rozenblit: 9781477532867: Amazon.com: Books and is copyrighted so I don't want to post it online.

From what I gather, this design is a fairly new upgraded circuit to his previous amps. It eliminates two transformers and a drive tube yet maintains all the OTL goodness.

He also has a 300B OTL monoblock project in there that is going to be a must build for me. The tubes aren't cheap, but the sound is supposed to be second to none. "The most glorious 1W in all of audio" is the claim. I have heard nothing to refute it. My long term plan is to biamp my Altecs and run the 15W OTL into the 15s and the 300Bs into the horns.

BTW, if you're ditching your Sony, what are you going to use for a preamp? I don't think a preamp is a must as it has an input sensitivity of 2.2V, but it is recommended.

Click around his website. Bruce has a refreshing DIY mindset and interesting philosophy with respect to audio. He also has an interesting DIY speaker project using full-range Tang Band 8" drivers. I built a pair for <$600 and they sound excellent for that $$$. 95dB sensitivity is very loud with 3W. They will work nicely with 1W and scream with 15.

Transcendent Sound DIY Specialist in Vacuum Tube OTL Amplifiers
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Old 22nd November 2012, 01:54 PM   #40
freax is offline freax  Australia
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Originally Posted by Alan Cohen View Post
Which amp? The 15W OTL? If so, the schematic is published in his book Tubes and Circuits: Bruce Rozenblit: 9781477532867: Amazon.com: Books and is copyrighted so I don't want to post it online.
Bugger, oh well I'll just have to use my imagination and your build pictures for now :P

Quote:
He also has a 300B OTL monoblock project in there that is going to
be a must build for me.
I've wanted to build a 300B amp for almost a decade, enjoy

Quote:
BTW, if you're ditching your Sony, what are you going to use for a preamp? I don't think a preamp is a must as it has an input sensitivity of 2.2V, but it is recommended.
Yes I saw that this afternoon, for now I will do without and just power it with whatever the TDA1543 can muster, I've thought about swapping out the driver tube(s) with something with a bit more gain, I would like to try the 12AU7 but it hasn't got more gain than the 12AT7...If it becomes an issue I might get a really high quality 12AX7... or something with a gain of 90 instead of 60 (12AT7).

I'll have to use my turntable preamp if things get too desperate, I'm not going to build a tube preamp just yet :P I might be able to fit a battery tube preamp into the TDA1543 DAC which /might/ put out 2.2v pp but it would be a super tight squeeze.

I'm outta luck until I can get a preamp and will just have to make do.

This is what the DAC puts out:
Analog first output
The output voltage of 0.7 M RMS when connecting a digital signal corresponding to 0 dB
The first output OR1/OL1 is for connecting to a tube amp that has high input impedance, 300k Ohms - 500k Ohms and sensitivity of 300 mV.
XP3
Pin 6: Out R1
Pin 5: Common bus, GND
Pin 4: Out L1

Analog second output
The output voltage of 0.7 M RMS when connecting a digital signal corresponding to 0 dB
The second output OR2/OL2 is for an upgrade. You can connect Up Transformer through a capacitor 10 uF. For example Sowter 4383 or equivalent. In this case, you can use an amplifier with an input impedance of 47k ohms and a sensitivity of 1V.
XP3
Pin 3: Out R2
Pin 2: Common bus (GND)
Pin 1: Out L2

http://www.ebay.com.au/itm/130681589933?ssPageName=STRK:MEWNX:IT&_trksid=p398 4.m1497.l2649


Quote:
He also has an interesting DIY speaker project using full-range Tang Band 8" drivers. I built a pair for <$600 and they sound excellent for that $$$. 95dB sensitivity is very loud with 3W. They will work nicely with 1W and scream with 15.
No good for me, I'm not in the mood to be cutting wood up, I've got my eye on the Frugel Horn flat pack kits: SOUND WITH STYLE - CUSTOM LOUDSPEAKERS Frugel Horn MK3 kit flat pack Mark Audio Fostex Tang Band

Last edited by freax; 22nd November 2012 at 02:15 PM.
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