classe twenty five and classe fifteen


Hi there I am curious to what the differences are between these amp I am guessing that they are built the same years and they have the same design philosophy but the twenty five is the higher model, i cant seem to find to much info on the 25, any info would be greatly apperated.

Thanks,Paul
paulficarella
I bought a DR-25 in 1989 to drive a pair of Apogee Stages, later used it to drive Apogee Duetta Signatures, and still use it today in bridged mono mode to drive the Martin Logan Stage center channel in my HT setup. The 25 was simply a change in name from the DR-25 since Dave Reich (DR) left Classe' in about 1991 and they had to drop the DR in the name.

The 25 is an excellent amp. It outputs 250 w/ch into 8 ohms and doubles up as the speaker impedance halves (500w/ch into 4 ohms and 1000 w/ch into 2 ohms). It delivers lots of current as well. It runs relatively cool for a high power design and is as reliable as a brick.

The 25 is refined and dynamic, if a little dark, and can easily drive most speakers with low efficiency and/or low impedance loads. Mine has been in service for 20 years and is still going strong. Never ever had it go into protection mode, even driving Apogees and Thiels at high volumes.

I never owned the 15 but did try a DR-10 before (quickly) trading up to the 25 and there was no contest. The 10 was dull and lifeless compared to the 25. Even though I did not have the money at the time for the 25, the difference was so profound that I bit the bullet and traded up within a week. Can't recall exactly how I swung the extra $2500 for it, but I did and it has proven to be one of the best audio investments I have made.

I have heard the fifteen in a few systems and feel that it is, predictably, halfway in between the 10 and the 25. My advice is to hold out for a 25. You will be glad you did.

Good luck.
I was a Classe dealer for many years and concure that the 25 is an excellent amp. The 15 was also very good, but the 25 was better.

There were actually a few small changes from the "DR" series to the "numbered" series:

The improvements to the Ten, Fifteen and Twenty Five vs the DR-10, DR-15 and the DR-25 are as follows:

* Current delivery to the front end was improved with better impedance matching between supply and signal bearing circuitry.

* Amount of input stage regulation was reduced.

* Output stage emitter resistor values were changed.

These changes resulted in the new amps sounding more alive and having more "jump factor". The DR series were a little darker and warmer sounding.

I still think the best sounding Classe amps were the DR3VHC and the DR8 and DR9.
Mofimadness,

I thought the same thing, but when I called B&W/Classe' Audio about 2 years ago to inquire about having my DR-25 upgraded to Twenty Five status, they told me that any changes between the models were extremely minor and that there would be no audible difference.

I'm sure that you are right. As the original owner, I was not entirely pleased with B&W's/Classe's reluctance toward helping me with that. I actually tried to contact Dave Reich, but apparently he is no longer involved in audio.

DR probably works better with forward speakers and the Twenty Five with laid back ones. Regardless, it is a hell of an amp. I don't think I would kick either out of bed ;)

Always heard good things about the first Dave Reich designs, but never actually heard them. Based on specs, they were not rated high on wattage, but I understand that ran in Class A all the way to clipping?
Dlcockrum,

If you look at the product literature, (I still have some), it lists the amps output(s) as A/B. I swear though, that Glen Grue once told me that the amps do run Class A up to a point, but I really can't confirm or deny that. I always thought that they did. I had a pair of DR8's running mono and LOVED them on my Apogee Stages and I had a DR3VHC on a pair of Acoustat Model Sixes that ROCKED!
Sorry, I needed to clarify that the DR3, DR3B and DR3VHC were indeed Class A amps. The DR8 and DR9 were listed as Class A/B amps, but "might" have ran Class A up to a certain level.
I owned both the Twenty Five and the DR25 in the same system, and much preferred the Twenty Five, despite Classe telling me the technical differences were minor. I found it more dynamic, alive, open sounding. I originally explored the Twenty Five, already owning the DR25, after reading the Stereophile review, where the reviewer (LG I believe) very much liked the Fifteen and did not like the DR15 at all. My speakers at the time were Snell B Minors.
The BIGGEST change between the DR-25 and the Model 25 was the removal of Dave Reich's name off the internal circuit board and replaced with Glen Grue's name. I still have the original DR-25 and Model 25 promotional literature and there is NO mention of any updates nor changes to the specifications. Dave Reich is a designer, Glen Grue is a marketer.
The worst power amp I have ever owned by far was a DR10, which was bland and inspid to a point that it made everything sound like a loud AM radio! I replaced it with an old, old Son of Ampzilla which was superior in every way, and sounded far more powerful and snappy, although its rated power was quite a bit lower. Ulimately a pair of the rare-as-hens-teeth Exposure XVI monoblocks showed what a huge amount of music was being strangled to death by the DR10s. I ended up giving the DR10 away.
I don't doubt you had a bad experience with the DR-10. You don't say what speakers and other equipment it was mated with. Proper matching is everything. I've been in this hobby for 40+ years and have owned more amps (tube and solid state, mid-fi and high end) than I can count on the digits of both hands and feet. Not one of them ever came close to sounding like an AM radio, not even the Phase Linear 400 Series 2 that I have in my collection. Peace.
I OWNED THE 15, IT WAS A LITTLE LACKING IN THE BASS COMPARED TO OTHER AMPS I'VE OWNED BUT IT WAS A REAL NICE AMP BUILT LIKE A TANK. THE PROTECTION CIRCUITS ARE VERY SENSITIVE, IT WOULD SHUT DOWN WHEN USING TUBE PREAMPS SO I HAD TO SELL IT, IF YOU DO NOT MATE WITH TUBE PREAMP IT IS FINE!
I run the 15 amp with a tube preamp, specifically a Modulus 3A preamp. I am very happy with the marriage.
Hey, Brf, I think the biggest change was the face plate (removal of DR from all model names) that would be the most obvious to most people. (Even the next gen of Classe (when the Fifteen change to the CA-150) was the same amp.

I like this Classe series and still own a Fifteen. Thought the bass is great, the mids and highs lack allot of detail but still sound okay, but no match for the inter detailed mids and highs from Krell of the same vintage. just mho.
The difference between the 15 & 25 are that the 25 has more pairs of output transistors.
The 15's bass was the equal of the KSA-250.
The Classe 15's bass is no where near as good as the Krell KSA 250. In fact, very few amplifiers can match the bass impact and depth of a KSA 250. Besides, what do you know about bass....you own Merlins :-)
Yuck, yuck, yuck.

Dick Olsher(I think)reviewed it in Nov '94. I purchased a '15 based on this review after I returned form Daharan, Saudi Arabia(volunteered for 91 days temp duty to afford equipment since the pay was tax-free once you entered Saudi air-space).
I have bought a used Twenty-Five to drive a pair of KEF 103.4. It has matched pretty nice.
Appreciated if someone could share the manual/instruction with me.
Thanks.
I used a DR-10 for several years, and replaced it with a CA-300. The 300 was a major improvement across the board. More detailed, more dynamic, and a more even tonal balance. In looking at the circuitry inside, I noticed the DR-10 had a coupling capacitor whereas the CA-300 was direct-coupled. The 300 also had a large number of small power supply capacitors and the 10 used a single pair of large caps. Classe mentioned the power supply changes in their literature at the time.
This is a question is ear marked for "mofimadness" (the Classe dealer).
Mo - you were saying a couple of things.
#1: that the DR-9 was 1of your faves. Is it a sweeter amp than the Classe' - 25?
#2: you said you ran your a pair of DR-8's in mono. I ran a pair of DR-9's in mono & the amps sounds way better in Stereo than it does in mono, there's no comparison! That's why I'm looking at a Classe' - 25, I need the power. Did you do anything with your DR-8's other than flip the switches at the back?
#3: Between the Classe' - 15 & the Classe' - 25, which did you prefer & why?

Bill

I had the DR25 Nice robust amp).

From memory I recall (long time ago) both DR25 and DR15 had balanced inputs, these were a bit of a hoax as they were just an opamp that summed and they fed into the single ended input afterwards.

Better sound is obtained by just using the single ended inputs straight into the discrete input transistors.

Inputs are also capacitor coupled, I replaced the 5uf electrolytic coupling cap for a better quality plastic one for a further improvement in sound, and increased the Class A bias a bit more so the heatsinks ran at 50c on a hot day 30c.

Cheers George

#1: that the DR-9 was 1 of your faves. Is it a sweeter amp than the Classe’ - 25?

Yes.  Sweeter, warmer and smoother.

#2: you said you ran your a pair of DR-8’s in mono. I ran a pair of DR-9’s in mono & the amps sounds way better in Stereo than it does in mono, there’s no comparison! That’s why I’m looking at a Classe’ - 25, I need the power. Did you do anything with your DR-8’s other than flip the switches at the back?
Your’s are the first comments that I remember liking the stereo version over the mono better? I had quite a few customers come back and buy a second amp for mono. I guess it would depend on the speakers they were driving, but for most of the demanding speakers of the time, the monos were the way to go.

#3: Between the Classe’ - 15 & the Classe’ - 25, which did you prefer & why?

The 25 was better. Better bass control and extension. Better grip on the high frequencies, effortless power when needed.


If anyone knows the answers, wd be much appreciated.
What's the wattage consumption on the 25? 
And do they produce alot of heat? 
If anyone knows the answers, wd be much appreciated.
What's the wattage consumption on the 25?
And do they produce alot of heat?

According to the literature in my dealer binder, the 25 has a power consumption of 325 watts at idle.

They really don't run that hot.  Depends on the volume setting and what speaker it is driving, but normally, not that hot...which I know is relative, but that's the best answer without knowing all the parameters.


I owned a fifteen, and it was a very nice amp. Solid, musical, pleasant, flowing and rhythmic. I liked it a lot, in my second system, driving a pair of vintage Ryan MCL3. Seemed appropriate vintage for the speakers.
I wasn’t really looking to replace it, until I happened to get an opportunity to A/B it against a pair of modern hypex nCore monoblocks... :-) 
willmacc6 posts09-28-2018 1:31pmIf anyone knows the answers, wd be much appreciated.
What’s the wattage consumption on the 25?
And do they produce alot of heat?

Classe DR-25 a very nice reliable amp, sweet and never in your face, a little boring.
They run factory spec 22mV across their .27ohm emiter resistors, around 10watts Class-A per channel at idle, warm to touch.
I raised that and got better sound, so the heatsinks after an hour of idle at 28c ambient were just uncomfortable for the palms of my hands after 6 seconds around 50c, this was more like 35mV across the .27ohm emiter resistors.

Mains fuse ratings are
100v-120v 12amp fast blow
220v -240v 6amp fast blow
This is not indicative of the power consumption but more the inrush current to charge the power supply caps.

If anyone wants the service manual PM me with your email address. I’ll send it out once to the first one, but you must send it to others if they want it here on Audiogon.

Cheers George
IMO the Classe Omega Reference monoblock amps are still the best sounding and performing amplifier Classe ever made to date.

Thanks guys. The model I saw is the later 25 (without DR) ie after founder was stitched up and booted out.

So I take it thats's 25w consumption at standby or idle? And then with any signal/volume its the full class A monte, no matter 'watt'
 :)
willmacc7 posts09-28-2018 6:17pmThanks guys. The model I saw is the later 25 (without DR) ie after founder was stitched up and booted out.

So I take it thats's 25w consumption at standby or idle? And then with any signal/volume its the full class A monte, no matter 'watt'
 :)
The 25 in the DR25 is short for 250w into 8ohms, nothing to do with power consumption.

Cheers George
If that was true then the 15 would be 150 wpc and it's in fact 175 wpc. So many on here are regurgitating nonsense . I haven't a clue from where they get it. The differences between the DR versions and the subsequent versions are indeed clearly audible and a real upgrade. Anyone who says different doesn't have a clue. 
If that was true then the 15 would be 150 wpc and it's in fact 175 wpc.
I don't know about the DR15. 


The 25 in the DR25 is short for 250w into 8ohms
https://www.hifiengine.com/manual_library/classe-audio/dr-25.shtml

The idle current power consumption is around 100w with factory adjusted bias give or take. I took them up much higher so heatsinks were at 50c

Cheers George
Your link is standard specs and provides no support to your assertion that the 25 stands for 250wpc. As I stated, does that make sense when the dr15 has 175wpc? The DR 8 I suppose has 80wpc, the DR 9 has 90wpc and DR 3 has 30wpc? Do you honestly believe the DR 25 to be an outlier in the nomenclature?
Jeez, the Model 10 amp was 120wpc, the 15 was 175wpc and the 25 was 250wpc. Taken directly from the specs in the owners manuals.   These are all into 8 ohms.  At 4 ohms they doubled their power.  I owned both the 10 and 15.  The 10 sounded better as the 15 was too dark sounding.  There is much better out there, used or not. 
The model numbers of the Classe amplifiers had nothing to do with the power rating.  They were close, but not exact.  Even the "Seventy" amp was rated at 75 watts.
CA100 CA200 CA300 CA400 CAP80 CAP100 CAP150 all same
Sorry, I meant to older, classic, vintage, original Classe amps.
 I think the next generation was 101, 151, 201, 301, 401 maybe Classe just having some fun

I have to ask if the classe 15 could handle 2 ohms.... looking for amps for my thiel cs 3.6. Preferring to get warmer (but not too warm) sounding amps to keep things from sounding aggressive.
Thiel’s are pretty bright

I would say no, as the DR25 just had enough current for the 3.6's when I had them.
The low impedance value explains the CS3.6's need for the iron-fisted Mark Levinson No.23.5 to provide control in the bass; the CS3.6 would appear to be current-hungry. 
Cheers George
So I got a pair of classe 25z I don’t know if they’re dr or not. I also have no idea what I’m looking at inside as the inside looks way different. Any classe aficionados on here that could look at the pictures and say? One seems to have updated output boards attached. And the other seems to have the original boards on the outputs but they added 4 more filter caps to the filter board
Open the cover and look at the circuit boards.  The main board should say "designed by Glen Grue". if it is, its the 25.  The DR25 was designed by David Reish.  Glen Grue pushed him out when he took over the company.
just look at front panel...either the earlier DR-25 or later Twenty Five