Adcom pre amps

disneyjoe7

I heard somewhere that Adcom made some Pre's and not so Pre's does anyone know what models where good and other which are not?

ben62670

If you are looking for a solid Adcom pre I would stay away from the 4xx's, and the 5xx's minus the GFP-565. The 7xx Pre's are the ones to look for. Hopefully H9 will chime in. He knows Adcom pre's much more than I.
Ben

disneyjoe7

I was thinking the 7's where bad no?

heiney9

The best pre amp Adcom made was the GFP-750. It was a Nelson Pass design based very closely on his $4000 Aleph P, which is considered among the best sounding SS pre-amps. The 750 is a dead neutral preamp in both passive and active mode. If you don't like dead neutral sounding components I'd steer clear of it.

I have one I'm borrowing from my brother...........it's dead neutral and when paired with my warm, open Aleph 30 amp it certainly sounds much different then what I'm used too. For me the jury is still out as to whether or not it has the correct synergy I'm looking for. That said, it's a fantastic sounding pre-amp.

The GFP-750 retailed for between $1250-1500 depending on when it was purchased. Typically mint units sell in the $800-950 range used with lesser units (many missing the remote) selling for $650-800. I believe you can still get the remote from Adcom, but if you find a unit w/o it I'd call Adcom to make sure.

The GFP-710 and GFP-715 are also among their better designs. Anything with a tuner in it is not the greatest and leaves a lot to be desired. The GFP-555 is also one people commonly see.......not the greatest unit either.

This would be my only recommendation for Adcom pre-amps

GFP-750
GFP-715
GFP-710.......in that order. Anything else short of free; I'd look else where.

Hope this helps

Linky to a review from Stereophile http://www.stereophile.com/solidpreamps/133/

H9

P.s. we were using the GFP-750 to run Ted's currently acquired (by my brother) BAT VK-120's since the Adcom is a true balanced pre and they sounded absolutely fantastic, dynamic, balanced, very open and detailed, not a hint of harshness. If it's good enough for those; it's good enough for anything

comfortablycurt

Good to know. I've been strongly considering the GFP-710 for my first pre-amp, with a later upgrade to the 750. Sounds like I'm on the right track.:)

I'd been wondering whether or not the 750 was actually fully balanced or not...thanks for answering that for me Brock.

Does anyone know whether any of the Adcom amps are fully balanced? I'm planning on picking up an Adcom GFA-555 for the power amp, which doesn't have balanced outs. I've been considering an Adcom 555SE, or 5802 for a future upgrade though. Those both have balanced outs, but are they truly balanced, or just bridged? Anyone know?

Systems

It won't beat the 750 but if one is really into modding the 565 can be made into a good little pre.

heiney9

comfortablycurt wrote: »

Good to know. I've been strongly considering the GFP-710 for my first pre-amp, with a later upgrade to the 750. Sounds like I'm on the right track.:)

I'd been wondering whether or not the 750 was actually fully balanced or not...thanks for answering that for me Brock.

Does anyone know whether any of the Adcom amps are fully balanced? I'm planning on picking up an Adcom GFA-555 for the power amp, which doesn't have balanced outs. I've been considering an Adcom 555SE, or 5802 for a future upgrade though. Those both have balanced outs, but are they truly balanced, or just bridged? Anyone know?

The new 555 SE and 5802 are balanced. Have a peak at the owner manual DL's at the Adcom site to find out others. I believe the 5800 is as well.

comfortablycurt

heiney9 wrote: »

The new 555 SE and 5802 are balanced. Have a peak at the owner manual DL's at the Adcom site to find out others. I believe the 5800 is as well.

Good to know. Thanks Brock.

I checked the manuals for both, but it didn't mention anything about being fully balanced, or true reference differential or anything of that nature, so I wasn't sure. It simply said "balanced". From what I've gathered, being "balanced" doesn't always mean that it's actually truly balanced. Thanks for the clarification though.:)

So what would be considered an average/fair price for a GFP-710? I've seen them go for around 150-200 for the most part. Would you say that's a fair price? I saw on on ebay recently with a BIN of 125 +shipping...and it didn't sell. I was really wishing I had the money.

Toolfan66

Thanks for this info as well. i have been looking into Adcom for a 2 channel setup.

disneyjoe7

Thanks for the education, I was playing with a GTP-500 pre amp to bypass my HT receiver for 2 channel. I see that was just a toy, but it sounded better then the HT receiver.

Systems

comfortablycurt wrote: »

. From what I've gathered, being "balanced" doesn't always mean that it's actually truly balanced.

Correct most preamps and amps with balanced inputs/outputs just have an extra circuit stage called an inverter.Depending on whether its an input or output,the inverter either creates the negative(inverted) half of the balanced signal or sums it back to single ended.

As H9 pointed out the 750 is a true fully balanced design meaning it duplicates the entire circuit for both the positive and negative halves of the signal.In the case of the 750 ,in active mode it uses just one MOSFET for each half so has a very short and simple signal path.
There are some amps that are are fully balanced from input to output but most of these are of the mega buck variety.There are some real performance advantages with the fully balanced design especially so when using balanced cables.

comfortablycurt

GV#27 wrote: »

Correct most preamps and amps with balanced inputs/outputs just have an extra circuit stage called an inverter.Depending on whether its an input or output,the inverter either creates the negative(inverted) half of the balanced signal or sums it back to single ended.

As H9 pointed out the 750 is a true fully balanced design meaning it duplicates the entire circuit for both the positive and negative halves of the signal.In the case of the 750 ,in active mode it uses just one MOSFET for each half so has a very short and simple signal path.
There are some amps that are are fully balanced from input to output but most of these are of the mega buck variety.There are some real performance advantages with the fully balanced design especially so when using balanced cables.

Thanks for the info GV. It's appreciated...that cleared up several things I'd been wondering.



I was checking some of the manuals on Adcom's site...and according to them, the 5802's balanced inputs are bridged. Correct me if I'm wrong, but this isn't a truly balanced design is it? This would be utilizing the "inverter" that you described if I'm reading it right...correct?

Sorry for derailing the thread here.;)

disneyjoe7

Don't worry about the derail its all good. Bring it on.

heiney9

comfortablycurt wrote: »

Thanks for the info GV. It's appreciated...that cleared up several things I'd been wondering.



I was checking some of the manuals on Adcom's site...and according to them, the 5802's balanced inputs are bridged. Correct me if I'm wrong, but this isn't a truly balanced design is it? This would be utilizing the "inverter" that you described if I'm reading it right...correct?

Sorry for derailing the thread here.;)

I believe the 5802 amp is a fully balanced design. But GV should know for sure. I can't find my schematic, plus I'm lazy right now

Not sure about the "new" 555SE as the original 555 was NOT a balanced amp. My guess is the new 555SE might be of the "inverter" type.........haven't seen a schematic of it.

Systems

Well with only the manual to go by it is possible(can't say for sure without a schematic) that the 5802 is as H9 surmised a balanced design. The reason I say so is the absence of a bridging switch,which I believe is usually a feature on most of their models.It may have been omitted because the output stage is already operating in a bridged/balanced config.

The 555se is bridgable so is not a fully balanced design in stereo mode.

I should add that not all amps need an extra inverter for their balanced inputs,many( like H9's Aleph )sum the two halves of the signal at their the differential input stage.

comfortablycurt

Alright...thanks for the info guys.

So, if it came down to a choice between the 555SE and the 5802, which one would come more highly recommended?

They both seem to have a lot of great reviews...but I've also read a lot of reviews where people switched from a 555 to a 5802, and ended up going back to the 555. They have a much different sound from what I've gathered, due to the MOSFET's in the 5802. It seems that a lot of people really prefer the sound of the 555.

heiney9

comfortablycurt wrote: »

Alright...thanks for the info guys.

So, if it came down to a choice between the 555SE and the 5802, which one would come more highly recommended?

They both seem to have a lot of great reviews...but I've also read a lot of reviews where people switched from a 555 to a 5802, and ended up going back to the 555. They have a much different sound from what I've gathered, due to the MOSFET's in the 5802. It seems that a lot of people really prefer the sound of the 555.

5802 without question. A superb sounding amp....save up the extra coin/wait and get that one. It's quite a bit more refined than the 555, but then it should be.

I prefer the 555 over the 5500 (slight) but the 5802 is on a whole other level.

comfortablycurt

heiney9 wrote: »

5802 without question. A superb sounding amp....save up the extra coin/wait and get that one. It's quite a bit more refined than the 555, but then it should be.

I prefer the 555 over the 5500 (slight) but the 5802 is on a whole other level.

That's what I figured the case would be. Thanks for the info.

In either case, I'll be getting a GFA-555 to start with most likely. I can get one used for around 300, opposed to closer to 800 for the 5802. The 5802 is currently the prime contender for my next amp after the 555 though.

I haven't heard a whole lot of praise in regards to the 5400's or 5500's though really. Their reviews seem to be somewhat neutral in comparison to Adcom's other amps.

CRESCENDOPOWER

Don't bother! A pre-amp is the least critical component in any audio system.

POST#14:D

nooshinjohn

CRESCENDOPOWER wrote: »

Don't bother! A pre-amp is the least critical component in any audio system.

POST#14:D

more sarcasm

Blownrx7

Disneyjoe7,
disclaimer: Not trying to derail this thread, just offering some more options.

I had a GFP750 and it is a very good preamp. Certainly at it's price point, it's features and performance make a very compelling unit

BUT, although it is a very good it was not as good as I hoped.
If you are NOT set on getting a remote, check out the Aragon Aurum. I compared the two and the Aurum was easily much more transparent and from top to bottom, the Aurum bettered the 750. Much blacker background, less grain and plenty of bass slam.
It's typically in the $500-600 range.
Food for thought...

lakesailor

As a guy who used to own a ton of different Adcom over the years I can say from experience that Heiney9 is basically bang on in every post I have read in this thread.

heiney9

Blownrx7 wrote: »

Disneyjoe7,
disclaimer: Not trying to derail this thread, just offering some more options.

I had a GFP750 and it is a very good preamp. Certainly at it's price point, it's features and performance make a very compelling unit

BUT, although it is a very good it was not as good as I hoped.
If you are NOT set on getting a remote, check out the Aragon Aurum. I compared the two and the Aurum was easily much more transparent and from top to bottom, the Aurum bettered the 750. Much blacker background, less grain and plenty of bass slam.
It's typically in the $500-600 range.
Food for thought...

Not everyone digs the "truthfulness" of the GFP-750. I don't find a hint, not a hint of grain in the pre and no noise even putting my ear right next to the speakers........can't get much blacker than that. Different strokes for different folks. It's about as dead neutral as an active pre-amp can get and switching between active and passive (once the level is matched) there is very little difference.

Many people prefer a pre that has a adds a little "flavor" to their music....if that's the case you may not like this pre as it emphasizes both stellar and poor recordings equally.

H9

P.s. That's not to say that it can't be beat.....it certainly can but expect to pay over $3-4K to start to hear some differences.

Blownrx7

heiney9 wrote: »

Not everyone digs the "truthfulness" of the GFP-750. I don't find a hint, not a hint of grain in the pre and no noise even putting my ear right next to the speakers........can't get much blacker than that. Different strokes for different folks. It's about as dead neutral as an active pre-amp can get and switching between active and passive (once the level is matched) there is very little difference.....

My experience was different. The active mode did add grain. I verified it by operating in both modes AND comparing it to the Aurum and a Simaudio P5 (about as transparent as they get and very revealing of bad recordings).
BTW, my comments referred to the GFP in the passive mode which was superior to the active mode in my system (but not superior to the Aurum or the P5).

I'm not saying the GFP was unacceptable, just that I found something that sounded better in my system and offered a possible option that MAY be more desireable for someone else too.

YMMV

heiney9

Blownrx7 wrote: »

I'm not saying the GFP was unacceptable, just that I found something that sounded better in my system and offered a possible option that MAY be more desireable for someone else too.

YMMV

I was also just offering a bit more insight based on my experience. It's all good....finally a civil discussion on CP - lol . Not everyone likes or hears the same things.

Enjoy the music

H9

steveinaz

heiney9 wrote: »

Not everyone digs the "truthfulness" of the GFP-750. I don't find a hint, not a hint of grain in the pre and no noise even putting my ear right next to the speakers........can't get much blacker than that. Different strokes for different folks. It's about as dead neutral as an active pre-amp can get and switching between active and passive (once the level is matched) there is very little difference.

Many people prefer a pre that has a adds a little "flavor" to their music....if that's the case you may not like this pre as it emphasizes both stellar and poor recordings equally.

H9

That's where I am with the Placette and Benchmark DAC1 in a preamp mode. The Placette is neutrality defined---but I'm finding it a bit boring. My Benchmark is back in a preamp capacity, and I am digging the extra excitement, punch, texture, body. I forgot how good the DAC1 sounded in this role, now I'm back to rifling thru CD's again. I'm very seriously considering the Benchmark DAC1 PRE.

heiney9

steveinaz wrote: »

That's where I am with the Placette and Benchmark DAC1 in a preamp mode. The Placette is neutrality defined---but I'm finding it a bit boring. My Benchmark is back in a preamp capacity, and I am digging the extra excitement, punch, texture, body. I forgot how good the DAC1 sounded in this role, now I'm back to rifling thru CD's again....

I hear ya Steve.

I prefer the Adcom in "active" mode. I was looking at a Pass Labs Aleph "L" to go with my Aleph 30 amp, but it is essentially a passive pre-amp and I was afraid to take the plunge. Atleast the Adcom (also a pure Nelson Pass design) I can switch between passive/active plus it's fully balanced and has a remote.

People tend to slam Adcom as being mid-fi, but this pre is something special, a real stunner when mated with other exceptional gear. I am totally taken with the sysnergy I have going on right now.....euphoric at times.

H9

steveinaz

Exactly the right choice. Whatever the Benchmark is, I love what it does for my music; and that's all that matters.

I don't believe in the term "mid-fi." Equipment either meets the standard to produce music with a certain level of accuracy, or it doesn't. Audio snobs throw mid-fi out there as a way to feel better about spending more on a preamp than I did my last automobile...LOL

cnh

Ok,

We've talked about Adcom pre-s. I've heard one of the lesser models Heiney9 mentions above..wasn't that impressed with it on a GFA-555 I was buying! Seller was using that, the 555 and a McIntosh CD player with Devore Fidelity Giboon 3 bookshelves and a good sub...don't remember the model? So what about a non-adcom pre-amp for a 555. What would be good?

I don't like 'neutral' that much. Prefer something a bit 'smoother' and 'warmer'. What should I be looking at in the not too stratospheric price realm?

Also, does anyone know what GFA-555 original Large Caps look like? Are they a darker shade of baby blue? I haven't opened up the unit...yet but am trying to figure out if the Caps have been replaced or not. Either way those guys are 'huge'. What should I be 'listening' for in order to tell what shape my caps are in?

Thanks guys....

cnh

fbm211

Perhaps a tube preamp for warm sound in in order. If the caps in the 555 are bad you would probably know it by listening to it the first time. Here are some links to some pres on audiogon. http://www.audiogon.com/cgi-bin/cls.pl?preatran&1243173622&/Rotel-RC---972 http://www.audiogon.com/cgi-bin/cls.pl?preatran&1243123848&/Sansui-Ca-2000-Upgraded-power http://www.audiogon.com/cgi-bin/cls.pl?preatran&1243105134&/Classe-CP-35 http://www.audiogon.com/cgi-bin/cls.pl?preatran&1242942053&/Classe-CP-60-Preamplifier http://www.audiogon.com/cgi-bin/cls.pl?preatran&1242587484&/Acurus-RL11

Systems

If the caps are real bad you will hear some hum.