Adcom GFP-750 just came in, low volume

chandler9a

Okay, so my Adcom GFP-750 just came in and I waited a while to hook it up. It looks brand new and powers on just fine. Jumpers are in and using the unbalanced connections

However, I have to turn the volume at least half way up to get the sound to where I would listen to it. I can turn it all the way up and its not even close to ear bleeding loud.

I have it going from my NAD CD player to my dac via dig coax to the Adcom which is connected to my GFA-555
speakers are SDA-1C's.

I've taken the DAC out of the mix but no difference in volume being unusually low. It sounds fine but I feel like I should not have to turn it up to 3 O'clock to get it to a decent listening level.

Did I hook it up wrong?? It all seems pretty simple.

heiney9

Are you sure you don't have the passive section engaged?

H9

P.s. This is a solid pre, built like a tank. I don't understand all the issues people are having with these. Well, in a couple cases as in Polkfarmboy, I can see why.

heiney9

Turn the volume way down before you start switching between active and passive

chandler9a

I have tried it in both modes and the same issue. Where should the volume be at normal listening levels? I mean by yourself with nobody else around and not ear bleeding.

The RCA's are hooked up into the main 1 out to the amp. seems simple enough but man its just not loud at all until I really turn it up and I never go past 11 o'clock on volume nobs.

heiney9

chandler9a wrote: »

I have it going from my NAD CD player to my dac via dig coax to the Adcom which is connected to my GFA-555
speakers are SDA-1C's.

This is very confusing verbage. Perhaps you could state in a more understandable way. Nothing should be "going from it" other than the ouput to the amp so I'm not sure what you mean by that. The NAD shouldn't be hooked to the pre-amp at all if you are using a dac, so that's very confusing the way you stated it.

H9

heiney9

The path should be

Source (NAD) cdp hooked to the dac via coax or toslink, dac hooked to unbalanced cd input on the pre, unbalanced Main 1 output of pre-amp should be connected to the power amp, power amp connected to the speakers.

Be sure passive is disengaged, cd input is selected. For mine, 9:00 is about normal listening with 11:00 being loud --in active mode. In passive mode anywhere from 12:00-3:00 depending on how loud the source was mastered, etc.

H9

chandler9a

Sorry it is a little confusing.

I tried the set up with and without the DAC, even with the CD player alone as the source (no DAC), the volume is the same.

the only output from the pre is to the amp. CD>Pre>Amp and CD>DAC>PRE>Amp is what I did. Both the same.

Could it be that it is not going into Active mode? Even though the light indicates that it is?

heiney9

When the light is on it's in Passive so it shouldn't be on if you want to listen to active.

I suppose it's possible it's stuck in Passive. It's just weird that in these cases it worked fine for the seller but then not for the buyer then when it;s returned to the seller it works fine. In Polkfarmboy's case it worked fine for the seller and an authorized service center said there was nothing wrong with it and when the seller recieved it back it worked fine. But PFB never got it to work properly.

Try some different I/C's is about all I can recommend at this point.

H9

chandler9a

Thanks for the input, H9. I am going to do some process of elimination for a bit. Could be cable, could be something else but I'll figure it out.

audiocr381ve

Sounds like you have it connected correctly.

This may or may not help but make sure the pins on the balanced input are in the correct holes.

I normally listen in passive mode between 8 and 9 o'clock. In active mode it's more near 8 o'clock for normal listening.

You can try main out 2. Make sure the processor loop isn't engaged as well.

heiney9

audiocr381ve wrote: »

I normally listen in passive mode between 8 and 9 o'clock. In active mode it's more near 8 o'clock for normal listening.

Hmmm.....when I have mine in passive it's up to 50% quieter at the same volume setting as active. It's strange you listen to both active and passive at the same volume setting. I would think passive would be a whole lot quieter.

heiney9

audiocr381ve wrote: »

.

This may or may not help but make sure the pins on the balanced input are in the correct holes.

You can try main out 2. Make sure the processor loop isn't engaged as well.

Both good suggestions. The owners manual will show you how the pins are installed. I believe FTGV is correct that having them in or out shouldn't affect the output, but perhaps if they are "in" the wrong position it might affect output.

Have you tried plugging into another input becides "cd". You can use the tuner or aux input instead of the cd input. See if that changes something.

H9

falconcry72

You could try using different inputs on the pre. Also try switching out cables.

audiocr381ve

heiney9 wrote: »

Hmmm.....when I have mine in passive it's up to 50% quieter at the same volume setting as active. It's strange you listen to both active and passive at the same volume setting. I would think passive would be a whole lot quieter.

Yea same case for me. Passive is a lot quieter but it's generally within "1 hour" of each other or so for normal listening.

chandler9a

Alright guys, Just did all of the above. No change. Pins are in the correct holes, swapped I/C's, tried AUX 1, main out 2, processor loop is not engaged...etc. Lastly, I did notice a huge change when I swapped my NAD 116 pre into the mix, volume is at a normal level.

So, it seems like the issue is somewhere in the Adcom pre, this CAN'T be what all of you are experiencing with this unit so I guess I should just contact the seller and see what he says?

falconcry72

Is the knob on the left set to "stereo"?

chandler9a

falconcry72 wrote: »

Is the knob on the left set to "stereo"?

Yes, it is.

heiney9

Sounds like you've done what you can do. No, that's not what I've experienced so contact the seller. Y'all have ne scratching my head that the past (3) 750's bought by someone here have had issues. I guess it happens, but I can't say I understand it. Just a run of bad luck I guess.

H9

chandler9a

yea, you know something is wrong when this NAD 116 sounds A LOT better than the Adcom 750. I was going to sell the NAD but it looks like its staying for now...

Thanks for all the help guys.

audiocr381ve

chandler9a wrote: »

yea, you know something is wrong when this NAD 116 sounds A LOT better than the Adcom 750. I was going to sell the NAD but it looks like its staying for now...

Thanks for all the help guys.

Seriously, talk about a run of bad luck. I know you've been waiting to hear this one for several months.

chandler9a

Its just weird because it came looking so perfect with all of its original stuff...but you never know what could have happened on the inside during shipping I guess. I hate it when the problem is not obvious and I can't figure it out.

I don't know everything about audio but I know enough to say this does not sound as people have talked/wrote about.

Worse things can happen, just part of the journey.

dkg999

heiney9 wrote: »

Sounds like you've done what you can do. No, that's not what I've experienced so contact the seller. Y'all have ne scratching my head that the past (3) 750's bought by someone here have had issues. I guess it happens, but I can't say I understand it. Just a run of bad luck I guess.

H9

Do we know that it's not the same Adcom 750 being resold and passed around? Stranger things have happened!

audiocr381ve

chandler9a wrote: »

Its just weird because it came looking so perfect with all of its original stuff...but you never know what could have happened on the inside during shipping I guess. I hate it when the problem is not obvious and I can't figure it out.

I don't know everything about audio but I know enough to say this does not sound as people have talked/wrote about.

Worse things can happen, just part of the journey.

So the passive mode isn't working at all? A whole lot less components working in this mode. Is it making decent sounds at least?

chandler9a

Passive mode and active mode "work." It's just that I have to turn it up half way to hear the music well and can turn it up all the way with it not being too loud. I am listening to my NAD at 9:00 now and thats pretty normal for me. There's not much difference, if any, in the volume in passive and active modes. Very little bass overall and altogether not impressed with the sound.

Can't be working right. Something's got to be wrong. And I didn't buy it here.

heiney9

Something is definitely wrong, even in passive mode you should get a nice full sound.

H9

audiocr381ve

Somethings wrong for sure. I had a NAD C162 (a step up from your 116) and although I didn't do a side by side comparison, I believe the Adcom would run circles around it. Let us know what the seller says.

chandler9a

the seller insists that nothing was ever wrong with it and he does have good feedback. I have to admit now that it has warmed up it sounds a lot better. But, I NEVER turn the volume to 3:00 and I can with this unit. Is that normal with you guys?

I know every pre has its own gain so maybe I'm just being paranoid. I just got back from a meeting and the sound has really opened up, I'm listening to some Brian Bromberg right now and the bass is coming alive for sure.


I think I might have gotten ahead of myself here and learned a hard lesson on letting things warm up, just hard to imagine I have to turn the volume up that much but maybe thats just the way this unit was designed. I'm going to take it to my Dad's system and try it on his 1.2TL's to confirm...

audiocr381ve

chandler9a wrote: »

the seller insists that nothing was ever wrong with it and he does have good feedback. I have to admit now that it has warmed up it sounds a lot better. But, I NEVER turn the volume to 3:00 and I can with this unit. Is that normal with you guys?

I know every pre has its own gain so maybe I'm just being paranoid. I just got back from a meeting and the sound has really opened up, I'm listening to some Brian Bromberg right now and the bass is coming alive for sure.


I think I might have gotten ahead of myself here and learned a hard lesson on letting things warm up, just hard to imagine I have to turn the volume up that much but maybe thats just the way this unit was designed. I'm going to take it to my Dad's system and try it on his 1.2TL's to confirm...

Dude 3 o'clock would be absurdly loud in passive mode. I just turned mine up to 12 o'clock (passive mode) and had to turn it back down. Are you in passive or active mode?

I don't feel like this piece needs any warm-up, especially in passive mode. I say send it back and tell him you have problem with it.

audiocr381ve

Is volume changing between active and passive?

chandler9a

I'm in active mode, the volume is slightly lower in passive but not much.

It is starting to get too loud at 3:00 and I would never listen to at that level anyway. The guy said he kept it at 12:00-1:00 for his listening. I still can't imagine anything close to that being even Okay.

I just wish I had another one to test it against, it could be just me and my system so its hard to tell.

thsmith

maybe is has a 250k ohm volume control, may have been replaced, just guessing but that would not explain the passive and active volume being the same.

In the manual is there options you can set inside that explain this ?

I had a 750 for a while but do not remember much about it.