Raka said:
I already answered to that question...
I bypassed EACH IC.
That's the ideal.
I can't recommend you anything less than the ideal.
We're talking fast components, if you don't whant to have oscillations, then bypass each IC.
Although near to each other, with only one cap it will be near from one and far from the other, or far from the two ICs.
In the end you'll see that the board size I did for my pre (10x5cm) is a miracle.
That's what I did.😉Raka said:
carlosfm said:
In the end you'll see that the board size I did for my pre (10x5cm) is a miracle.
Thanks, Carlos. The distance from the cap pin to both IC pins is less than 15mm, is this enough?
BTW, my prototype is now 40x30mm each channel.
Small and beautiful
Can you fit a 0.1 ceramic or polyester cap in that space?
I mean "glued" to the IC's supply pins.
I have the caps "glued" to the ICs, and to get the op-amps out of the sockets I have to do some gimnastics.
You can see it in the pics.
Very good, Raka.
Next time we'll make a walkman with a Gainclone inside.
Raka said:
Can you fit a 0.1 ceramic or polyester cap in that space?
I mean "glued" to the IC's supply pins.
I have the caps "glued" to the ICs, and to get the op-amps out of the sockets I have to do some gimnastics.
You can see it in the pics.
Raka said:
BTW, my prototype is now 40x30mm each channel.
Very good, Raka.
Next time we'll make a walkman with a Gainclone inside.
Low pass filter in GC
Hi,
first of all, holidays are great if you didn't know.
Back to hell (hot here...) I build one channel of my pre a la Carlos, with a buf634 and 637. The power supply is based on 7815 and 7915 with 4700uF before and 1000uF after them.
Sound is Ok (well, my tweeters are damaged and nobody seems to deal with peerless those days), not to say that is a terrific upgrade, but this should change as another GC better built is expected.
I've got one question to you Carlos, you told me that the buf634 runs hot here but I found that it doesn't. However, the 637 runs very hot (can be touched though) is this normal? I suspect that my bypassing is not good enough. Besides, the 7815 is warm but the 7915 is dead cool, what's here?
I want to add the low pass filter as read in Rasmussen (I like your surname) articles. Where and what to fit in my pre stage?
Hi,
first of all, holidays are great if you didn't know.
Back to hell (hot here...) I build one channel of my pre a la Carlos, with a buf634 and 637. The power supply is based on 7815 and 7915 with 4700uF before and 1000uF after them.
Sound is Ok (well, my tweeters are damaged and nobody seems to deal with peerless those days), not to say that is a terrific upgrade, but this should change as another GC better built is expected.
I've got one question to you Carlos, you told me that the buf634 runs hot here but I found that it doesn't. However, the 637 runs very hot (can be touched though) is this normal? I suspect that my bypassing is not good enough. Besides, the 7815 is warm but the 7915 is dead cool, what's here?
I want to add the low pass filter as read in Rasmussen (I like your surname) articles. Where and what to fit in my pre stage?
I believe that the LPF needs to be placed very close to the input of the GC, rather than in the preamp. This is based on advice from Pedja who may confirm this if he sees the thread. 😉
Re: Low pass filter in GC
Hi Raka,
It's hot in here too...
Let's see:
1 - I use the OPA627, not the 637, and my pre has a gain of around 2.4, not enough for the 637.
Below 5x, you'll have nasty distortion with the 637.
2 - I use 7818 / 7918, as I said, my PSU is +/- 18v.
Check the voltages before the regulators, it shouldn't be much more than 20v. If it's too high, use 7818/7918.
I did put 15 ohm resistors after the diode bridges, as you can see on the pics, because I had a higher voltage than needed and the regulators got very hot too (I had the transformer, didn't buy one).
I hope you're not using a 2x18v transformer with your 7815/7915 regulators, they will get hot.
3 - It's not normal that the op-amp is hot and the buffer is cold.
Oscillations? Have you bypassed close to each chip?
What gain do you have on your pre?
If it's bellow 5x (normal for a line pre), change the op-amps for the OPA627.
And the BUF634, without any heatsink, gets really hot!
Don't forget it's outputing 250ma current, enough to drive any line, almost any pair of headphones, and even a small speaker.
Oh, I'm finishing the film on my camera, and new pics will come next week.
The pre is finished, box included.
Hard work, but beautiful.
Today I'm gonna compare my pre and GC with some commercial products.
Let's say that the source will be a LINN CD12.
We're gonna put side by side my pre and GC with commercial (high-end) pre and power amps.
Stay tuned.😉
Raka said:
Hi Raka,
It's hot in here too...
Let's see:
1 - I use the OPA627, not the 637, and my pre has a gain of around 2.4, not enough for the 637.
Below 5x, you'll have nasty distortion with the 637.
2 - I use 7818 / 7918, as I said, my PSU is +/- 18v.
Check the voltages before the regulators, it shouldn't be much more than 20v. If it's too high, use 7818/7918.
I did put 15 ohm resistors after the diode bridges, as you can see on the pics, because I had a higher voltage than needed and the regulators got very hot too (I had the transformer, didn't buy one).
I hope you're not using a 2x18v transformer with your 7815/7915 regulators, they will get hot.
3 - It's not normal that the op-amp is hot and the buffer is cold.
Oscillations? Have you bypassed close to each chip?
What gain do you have on your pre?
If it's bellow 5x (normal for a line pre), change the op-amps for the OPA627.
And the BUF634, without any heatsink, gets really hot!
Don't forget it's outputing 250ma current, enough to drive any line, almost any pair of headphones, and even a small speaker.
Oh, I'm finishing the film on my camera, and new pics will come next week.
The pre is finished, box included.
Hard work, but beautiful.
Today I'm gonna compare my pre and GC with some commercial products.
Let's say that the source will be a LINN CD12.
We're gonna put side by side my pre and GC with commercial (high-end) pre and power amps.
Stay tuned.😉
Hi Carlos,
Hot here, I'm sorry hearing about your fire problems I wish you managed very soon this point.
I suppose it's not time to build a beefy class A amp.
I was mistaken, I actually used the 627. BTW, at first I used the OPA134 I had at hand and noticed that this gain problem resulting in .
I'm using a 15V trafo and 7815 (and 7915) and only the 7815 gets hot. I suppose both should be hot, right?
I used the same gain as you because I knew it worked beautifully for you.
I'm planning a more careful layout for the bypassing, and would like to include the lowpass in it. You don't have layout drawing or a more close picture of it, do you?
The only thing I've heard about the CD12 was from an old man (a 64 years, now linn dealer) that is strongly devoted to vinyl and that by no means is blind loyal (in the bad sense) to the scotish. He told me that the CD12 sounds analog. It's the very first time I heard him praising a CD player (he thinks the LP12 is just a decent player). I trust him.
Hot here, I'm sorry hearing about your fire problems I wish you managed very soon this point.
I suppose it's not time to build a beefy class A amp.
I was mistaken, I actually used the 627. BTW, at first I used the OPA134 I had at hand and noticed that this gain problem resulting in .
I'm using a 15V trafo and 7815 (and 7915) and only the 7815 gets hot. I suppose both should be hot, right?
I used the same gain as you because I knew it worked beautifully for you.
I'm planning a more careful layout for the bypassing, and would like to include the lowpass in it. You don't have layout drawing or a more close picture of it, do you?
The only thing I've heard about the CD12 was from an old man (a 64 years, now linn dealer) that is strongly devoted to vinyl and that by no means is blind loyal (in the bad sense) to the scotish. He told me that the CD12 sounds analog. It's the very first time I heard him praising a CD player (he thinks the LP12 is just a decent player). I trust him.
lost mail
Somebody sent me an e-mail with a question, but I accidentally deleted it before reading.
I don't know who it was.
Please send it again.
Somebody sent me an e-mail with a question, but I accidentally deleted it before reading.
I don't know who it was.
Please send it again.
Raka said:
Raka,
Sometimes there's a liittle more voltage on one of the secondaries.
Cheap traffos...
Check it out.
I have some pictures of the boards mounted on the box, on the film I'm finishing.
I don't remember if I took closeups of the boards, I'll find out when I finish the film.
As for the CD12, some people say it's the best cd-player in the world.
I don't know, but I'll take my dac with me (OPA627s, of course
), and let's see...
Oh, and the OPA134 is unity gain stable, maby you have a problem there?
Raka
Something seems wrong with your pre. If the BUF634 is set for wide band it definitely gets hot. The 627/634 combo draws about 50mA per rail (in a 10k load) if i'm not mistaken. The 627 definitely does not get hot. The combo sounds rather underwhelming with 7815/7915, but better sound is easy to get with a slightly more compicated regulator. You may have seen my post on the subject.
cheers
peter
Something seems wrong with your pre. If the BUF634 is set for wide band it definitely gets hot. The 627/634 combo draws about 50mA per rail (in a 10k load) if i'm not mistaken. The 627 definitely does not get hot. The combo sounds rather underwhelming with 7815/7915, but better sound is easy to get with a slightly more compicated regulator. You may have seen my post on the subject.
cheers
peter
analog_sa said:
Yes, I use the BUF634 in wide bandwidth mode.
And I also think that there's something wrong there, Raka.
The sound is so good even as it is (7818/7918) that if I changed them for something better you definitely would have to call the doctor.😀
high-end session
Well guys, let me tell you how it went.
We used a room where there was an Audio Analogue Pre and two monoblocks.
My friend had, for a start, mounted a pair of Epos 11 speakers (!), the same as I use at home.
The cd player was nothing less than a Linn CD12.
The guy definitely has an ear to detect subtle sounds and it's good to have someone like that at hand.
He called us (me and my brother) the attention to certain things that we wouldn't notice, but it was clear after he said it.
We used several combinations of the gear we had at hand, and several speakers.
Unfortunately, most high-end speakers these days are a tough load, hard to drive.
As they don't sell some of the brands of speakers that are usually more sensitive, we tested what we had at hand.
Time was limited, and we didn't test some things we would like to.
Summarizing:
1. Pick the right speaker and my LM3875 based GC sounds better than some expensive amps (including those AA monoblocks).
We didn't have time to play with amps as we would like to.
2. My pre is much better than that AA pre, but inferior to the Jeff Rowland Coerence😀 . Deam, that's a hell of a pre!
3. The Linn CD12 is an impressive cd player!
He didn't have the user manual at hand, so we could't activate the digital out (!), to use it as a transport and test my Audio Alchemy DDE v.3.0 Dac.
We used an Arcam FMJ cd player instead and the sound was murky. It's a bad cd-player to use as a transport. My suggestiion was to use and old Arcam 270 transport he had there.
He didn't whant to believe, as he likes the FMJ, but I insisted and the truth is that with the 270 transport the sound came alive.
Very good indeed.
Back to the CD12 and deam,😱 nothing can compete with that.
Well, when I got out I thought to myself that I must try the LM3886.
Maby some of the speakers that didn't play well with my GC would go well with the LM3886.
Don't forget that it has double the current.
Well guys, let me tell you how it went.
We used a room where there was an Audio Analogue Pre and two monoblocks.
My friend had, for a start, mounted a pair of Epos 11 speakers (!), the same as I use at home.
The cd player was nothing less than a Linn CD12.
The guy definitely has an ear to detect subtle sounds and it's good to have someone like that at hand.
He called us (me and my brother) the attention to certain things that we wouldn't notice, but it was clear after he said it.
We used several combinations of the gear we had at hand, and several speakers.
Unfortunately, most high-end speakers these days are a tough load, hard to drive.
As they don't sell some of the brands of speakers that are usually more sensitive, we tested what we had at hand.
Time was limited, and we didn't test some things we would like to.
Summarizing:
1. Pick the right speaker and my LM3875 based GC sounds better than some expensive amps (including those AA monoblocks).
We didn't have time to play with amps as we would like to.
2. My pre is much better than that AA pre, but inferior to the Jeff Rowland Coerence😀 . Deam, that's a hell of a pre!
3. The Linn CD12 is an impressive cd player!
He didn't have the user manual at hand, so we could't activate the digital out (!), to use it as a transport and test my Audio Alchemy DDE v.3.0 Dac.
We used an Arcam FMJ cd player instead and the sound was murky. It's a bad cd-player to use as a transport. My suggestiion was to use and old Arcam 270 transport he had there.
He didn't whant to believe, as he likes the FMJ, but I insisted and the truth is that with the 270 transport the sound came alive.
Very good indeed.
Back to the CD12 and deam,😱 nothing can compete with that.
Well, when I got out I thought to myself that I must try the LM3886.
Maby some of the speakers that didn't play well with my GC would go well with the LM3886.
Don't forget that it has double the current.
As it should be. The AA joke is using 5534s in a textbook circuit. So the GC didn't sound too good then?
cheers
peter
Raka said:
He was impressed with the sound but sceptic about the choice of speakers you have to make it play at 100%.
Then, at the end, he picked the CD12 and the CD we were listening to and connected it to a system with:
- Jeff Rowland Coerence pre-amp.
- Goldmund power amp (I don't know the model, but it was a monster).
- B&W 800 signature speakers.
Each balanced interconnect costs around 1500 Euros (1m!).
Deam, it sounded very good.
It's hard to impress a guy that listens to systems like this everyday, isn't it?
Anyway, it's an old friend of mine and my main objective here was to test my gear, nothing more.
Oh, and let me tell you that he was a sceptic but I convinced him some time ago to take his Micromega amp to my house for a few days.
Some mods and I returned it to him.
He is very happy with the sound now, so happy that he was thinking in buying a Lavardin IT, but not anymore.
Those crappy NE5532s on the pre had to go.😀
This guy called me crasy some time ago, but not anymore.😀
Did you try other speakers ? How efficient are the epos ? So the conclusion was that your gc was better than the AA amps on which speakers? I think that should be impressive enough.Don't expect the gc to drive the B&W Signatures though.
How much are those AA amps /pre?
How much are those AA amps /pre?
protos said:
The Epos played well, but curiously not as well as at my room.
That got me thinking that although my 4TC cable is good for my GC, the 8TC that we had yesterday for the tests may not be a good thing, as it may have more capacitance.
Most of the time we were testing speakers, in fact.
We tried so many that I can't remember all.
The ones that played better were curiously the smaller ones, and not so expensive, as Energy, Canton, System Audio, B&W 601 S3...
As I said, they don't have some of the more sensitive speakers that exist on the market, as Triangle, Cabasse, some JMLabs (they used to have them...).
Of course I don't expect the GC to drive the B&W signatures.😀
The AA pre costs around 650 Euros and the monoblocks around 700 Euros each.
We were busy with the speakers and lost our time, because there were plenty of pre/powers to be tested.
We got out at 11 without eating and we had to go dinner.
Then we were talking until 3am.
I said, and he agreed, that we should have tested other speaker cables.
I keep thinking that we were fooled by that.
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