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brown dogs

T

timH

pfm Member
no not labradors but brown dog adaptors - where can I get 'em from - I want to put some AD8610's in place of 8 pin Dil OP27's

Tim
 
Brown dogs

Tim

How quickly do you need them? I was thinking of buying a few and having them sent to my sister in law who lives in LA. She is visiting us in a couple of months.

How easy are they to solder, I am very much a novice.

Also, as usual, I can’t decide which op amps to use. Maybe I should start off with something inexpensive considering my inexperience.
 
I could do with 6 at the most. I'm starting off with a couple of AD8610's to start with - I got them as free samples from AD. They look impossible to solder but I thought the same about some smd resistors and they were a lot easier in practice.

I could probably wait a while - but couldn't your sister-in-law put them in an envelope

Tim
 
I am getting a bit confused as to the type I need.

I need a dual op amp and I am considering using 2 AD825's on one adaptor. The adaptor I set the link to is supposed to convert 2 AD825's to a single DIP. But I cant see it can, there are only 8 pads to solder too, surely the should be 16.

Also, I have just fitted to my CD player a couple of sockets which Farnell described as DIP sockets, they also sell DIL socckets under a different code number. The technical data sheet for both items are identical. Is a DIL socket the same as a DIP socket
 
I think they've got a glitch with their pictures. If you scroll down the link you posted and click on through hole dip it takes you to a picture of what you're looking for (maybe)

don't know what dip and dil mean
 
Hi Tim

I think the through the hole DIP is for making a dual 8 pin DIP out of 2 single 8 pin DIP's

DIL = Dual In Line.
DIP = ?????

I need an adaptor that will take 2 surface mount OP Amps and output to a 8 pin DIL. The words say it will but the picture doesnt. (as far as I can tell).
 
Fatcat

I think you're right.

Blow it - it's for the M.T.D. tray (much too difficult) I'm going to save up for some OPA627 Dip8's

Tim
 
DIL means dual in line
DIP mean dual inline package

As far as I understood they meant the same thing.

Of course, its friday now so I am much more interested in dipping my chips into dill sause and eating them all up.
 
Got home to find my LM6172 op amps had arrived. Quickly ate my fish, chips and peas, fitten new op amps into my DIP sockets. Played a few CD's. Not happy. Sounds awful. Although last weekends non oversampling of the TDA1541 had also made things worse.

In short, the first two mods to my CD player have made things worse.
 
fitten new op amps into my DIP sockets
Click to expand...

LM6172's are fast op-amps; putting them into sockets is not a good move, since the added lead inductance reduces the decoupling effectiveness.

This could be part of the problem. It could also be that the original decopupling is not good enough for the faster op-amp and may need modification too.

Andy.
 
I found the LM6171 to sound bright even with better decoupling in my Arcam Alpha 5+.
What other mods have you done? I wouldn't recommend zero oversampling if you are just going to replace the op-amps

Here is a list of Op-amps I have tried in my modded Arcam for the I/V and filter,

AD811
Opa604
LM6181
LM6171
OPA132
OPA627
OPA637
AD825
AD8610
AD8065
OP27

In my system and with the other mods I have done to the Arcam, the OP27 used for both the I/V and filter stage sound better than all the others I have tried, the OPA627's are very good and musical aswell but sound too dark for me, I can see why some people like these
 
Andy

I just checked the 855 circuit diagram, you are correct. There are only 4 capacitors associated with each OP Amp. The reason I used the 6172's is the 6171's I used in my Rotel 965 sounded superb. I have just checked the 965 and it has 9 capacitors associated with each Op Amp.

Ron

I have partly followed the recommendations of John and Jake regarding the non oversampling. I have removed pins 1, 2, 3, 15, 16 and 18 plus linked the vacated holes.
I have read though every post regarding oversampling hoping to find a clue as to where I have gone wrong. I have found that you have also tried the above mod, but found it screwed up timing and bass. Is my understanding of the above correct. That is exactly what is now wrong with my CD player.

I was intending to cut track joining pin 2 and 4 of TdA1541, join pin 4 of TdA1541 to pin 9 of SAA7220 filter next.

With regard to other mods. I have also bought some 11DQ10 diodes, LM337’s and LM317’s and I intend replacing some of the capacitor and resistors.

My logic in doing the non oversampling first was the fact that I thought this was the most difficult job to do. I didn’t want to do replace a load of components only to kill the CD player doing the non oversampling at the end.

I replaced the op amps with LM6172’s on the basis that the tonal balance may not be correct, but because of there very revealing nature I would be able to hear more clearly the effects of future mods.
 
Do the clock mod next but also think about the Black Gates and using LM329 or TL431 volyage references in the regulator circuits - also replace the fixed reg in the clock circuit with an LM317 circuit (if its an A5+ you have. I've fitted an external OSCAP to power the audio board using a transformer with twin 18v sec's 10000uF BC114's and MSR1560 soft recovery diodes. This gives smoothed +-27v to the board. (looking at super-regging it down to +-20v in the future)

Drop me a pm with your email if you want details

Tim
 
TL431 is for 5v output. Join legs 1 and 3 and you have a 2.5v reference. Use it in the second circuit on Neil Mcbride's site. R3 and R5 at 2k7 and R4 at 680r gives 5v output

Tim
 
Originally posted by fatcat
Andy

I just checked the 855 circuit diagram, you are correct. There are only 4 capacitors associated with each OP Amp. The reason I used the 6172's is the 6171's I used in my Rotel 965 sounded superb. I have just checked the 965 and it has 9 capacitors associated with each Op Amp.

Ron

I have partly followed the recommendations of John and Jake regarding the non oversampling. I have removed pins 1, 2, 3, 15, 16 and 18 plus linked the vacated holes.
I have read though every post regarding oversampling hoping to find a clue as to where I have gone wrong. I have found that you have also tried the above mod, but found it screwed up timing and bass. Is my understanding of the above correct. That is exactly what is now wrong with my CD player.

Do you have the Alpha5+? Remember that if you do the zero oversampling mod you are bypassing the filtering so it can sound a bit harsh etc if you don't do a few other mods, the 5+ has a chip that helps alot, when John did the zero oversampling mod he bypassed this chip aswell so it sounded worse, there is also two capacitors in a circuit that lowers the output voltage of the TDA1541 to near zero, these need to be upgraded to better types.

I was intending to cut track joining pin 2 and 4 of TdA1541, join pin 4 of TdA1541 to pin 9 of SAA7220 filter next.

Yes, this is a good mod

With regard to other mods. I have also bought some 11DQ10 diodes, LM337’s and LM317’s and I intend replacing some of the capacitor and resistors.

Be careful with the 11dq10 schottkies, I tried these for the audioboard,clock circuit etc in my Arcam but I didn't like them, they made the highs sound very clean but it screwed up the bass, try them and see what you think, it may be best to use the 11dq10's in the digital section and something like msr1560 for the analogue section.
Also its worth doing the mods Tim recommends regarding the LM317 in the clock circuit, this cleans the sound up nicely, also using the TL431's Lm329's in the regulator circuits would be worthwhile, I'm afraid you just have to try most mods and see what you think, it's took me about two years to get mine sounding how I like, I nearly scrapped it more than once.
The main thing I want now is a pair of Andy's super regs

My logic in doing the non oversampling first was the fact that I thought this was the most difficult job to do. I didn’t want to do replace a load of components only to kill the CD player doing the non oversampling at the end.

No, its not to hard to do, I think some people don't like the idea of having to desolder the filter chip and having to either bend the legs underneath or cut them off and then linking the holes together with wire

I replaced the op amps with LM6172’s on the basis that the tonal balance may not be correct, but because of there very revealing nature I would be able to hear more clearly the effects of future mods.

The only cdp I liked the LM's in was a Marantz cd63 KI I modded for a friend, the LM's seem to be best if used with bitstream dacs, the old multibit tda1541a's are not the easiest of dacs to mod but once you can get it right, you will be struggling to find anything that willl touch them
Click to expand...
 
hi fatcat,

The logical next move after the non oversampling mod is the cut the track and join the pins mod.

This should bring about an improvement.

Modding the Arcam is a rollercoaster ride with some highs and some lows.
All the mods have to be enabled in order to hear the finished result.
I found one of the biggest and most satisfying changes were the resistors.
They really smoothed things and gave an air of sophistication to an ordinary player.

My player is extemely revealing of microphone technique.
It really shows what is happening right at the start of the recording process whilst still portraying a performance rather than a static recording.

dogrun.gif
 
Thanks to everybody who has given me advice. Without it my CD player would not now be back on song.

Yesterday, I did the cutting the link between pin 2 & 4 and linking pin 4 to 9 mod. This improved things, it sounded OK but something was still not right. The bass and timing where wrong.

Today, I replaced the capacitors that feed the TDA1541 with a couple of Black Gates, plus replaced the capacitor that feeds the SAA7220 with a Black Gate. This really improved things. The midrange and treble became crystal clear. I was quite pleased but still the bass and timing where wrong.

I then replaced the LM6172’s with the original NE5532’s.

BINGO

Timing and bass returned, plus some. Although the midrange and treble are not as smooth, I am very very pleased with the way it sounds. It sounds a lot better than the unmodded player did. Strangeley, I am happy playing it at what sounds to be a lower volume.
The player I am modding is a Rotel 855. The DAC and filters appear to be identical to the AA5. I think I will try a dual version of the OP27 or OPA627, then leave the output section alone for the time being. The 855-output section comes with Black Gates as standard, plus the resistors in the output are not all the same types. I am assuming they will be better quality where required.

Next weekend it’s the diodes.
 
Hi Fatcat,

Glad to see you are getting some good results, do you have the service manual for the Rotel? Does it have a 74hc175 chip before the Dac? Also is the the TDA1541 the A version?
One of the best things I did to mine was replace the TDA1541A to the crown version
 
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