At first glance I wasn't sure exactly what I was looking at..... And I still dont, but they are cool pics anyway
Always Wanted to do this...
- Thread starter EchoWars
- Start date
how does it sound?
EW.. just wondering whether you have had any kind of opportunity to do any critical listening? Any comments or first impressions that you can share?
I'm curious to hear your thoughts on how this one compares to other similar Kenwood amps you have worked on, and am particularly interested in whether the opamp mod has had any impact on the character of the amp. You suggested to me in a PM that you expected it to be a fairly neutral modification from a sonic perspective.
EW.. just wondering whether you have had any kind of opportunity to do any critical listening? Any comments or first impressions that you can share?
I'm curious to hear your thoughts on how this one compares to other similar Kenwood amps you have worked on, and am particularly interested in whether the opamp mod has had any impact on the character of the amp. You suggested to me in a PM that you expected it to be a fairly neutral modification from a sonic perspective.
And that is my impression now. The 7100 has always been a very nice sounding amp, and is one of the best bargans on eBay, since Kenwood made so many of them. I don't know production figures, but I'm betting that Kenwood made more KA-7100's or KA-3500's than any piece ever on their manufacturing line.
Quantity does not exclude quality in this case, and this is a damn nice sounding unit. A OPA2604 as a unity-gain buffer imparts little to nothing to the sound of the amp, and overall it has the nicely detailed sound that the 7100 is known for. I don't think you will be disappointed.
I'm a happy camper!
Just got my upgraded KA-7100 back last night and had my first opportunity to listen to it for a while today.
My first impression is that EchoWars hit the nail on the head with his description. The amp has always sounded clean and clear to my ears, but with the recapping, cleaning, and modding work completed by EW it has never sounded better!!! :yes:
Unfortunately I can't do a direct A/B comparison, but it does seem slightly more detailed than before, and it almost seems like I can push the levels up a bit more without it sounding "loud" or uncomfortable. Less listener fatigue
might be a way of describing it... :scratch2:
At the moment I am driving a pair of Paradigm Titan v.3 speakers. It will be interesting to try this with other speakers, and even get some vinyl spinning!
Pics and nudies to follow shortly!
Just got my upgraded KA-7100 back last night and had my first opportunity to listen to it for a while today.
My first impression is that EchoWars hit the nail on the head with his description. The amp has always sounded clean and clear to my ears, but with the recapping, cleaning, and modding work completed by EW it has never sounded better!!! :yes:
Unfortunately I can't do a direct A/B comparison, but it does seem slightly more detailed than before, and it almost seems like I can push the levels up a bit more without it sounding "loud" or uncomfortable. Less listener fatigue
might be a way of describing it... :scratch2:
At the moment I am driving a pair of Paradigm Titan v.3 speakers. It will be interesting to try this with other speakers, and even get some vinyl spinning!
Pics and nudies to follow shortly!
OvenMaster
Baby, you're my winterblue
hpsenicka said:
You're feeding Titans?! That's a huge relief! I was wondering if my KEF's would be overdriven with my 90 wpc Yamaha, and I've been a bit afraid of frying them, but if you're using Titans with that Kenwood, then I can use my breadbox-sized KEFs with a Yammi! EW that looks like great work. Really pro. :thmbsp:
Congrats to both.
Tom
CDFixer- try this link
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shelby1420
Enjoying the music.....
Pacopico said:
Me too me too, every time i see one of these threads yakkin about EW working on people's gear :thmbsp: , looking at pictures of his work is like looking at pictures of a surgeon doing his or her thing
, pure magic, get little chills every time i think he is gonna be working on my amp HMMMMMMMMM Dr Glen, yeah that sounds right!!!!! :thmbsp:
more fun with the modded KA-7100!
A brief update ..
I have been thoroughly enjoying having my old KA-7100 back in service. It has become a daily driver... I currently have it set up in a small room/office, and am now driving a pair of Paradigm Atom v.3 speakers.
Today, just for fun I borrowed a Carver M-400a power amp, and have the KA-7100 pre-amp driving the Carver. The Atom's seem to enjoy having the extra power on tap.... but I am afraid to really crank it up! I sure can fill the 10x12' room with sound!
Still haven't found the time to finish cleaning up my spare KA-7100 to do some direct A/B comparisons.. I have been spending spare time just listening and enjoying! I hope to get to that this coming week.
Thanks again EW!
By the way... when comparing the preamp section original factory specs for both the KA-7100 and the KA-9100, I was surprised to find that the KA-7100 preamp appears to equal or surpasses the KA-9100 in some respects. The S/N ratios for the TAPE, TUNER, and AUX inputs is 110dB, as opposed to 100dB for the 9100. The freq resp for the TAPE/AUX is 10-100,000Hz (+0, -1.8 dB) on the KA-7100, as opposed to 7-50,000Hz (+0, -1.0 dB) on the KA-9100. Are these differences material in the real world, or insignificant?
EW.. any comments on whether the upgrades/mods would have improved upon any of these specs?
The PHONO stage specs require a bit more interpretation.... the KA-7100 takes a maximum input level of 200mV (rms) with THD 0.02% at 1,000Hz., while the KA-9100 is rated at 250mV (rms) THD 0.03% at 1,000Hz. I don't know what to make of these figures... seems like a teeny bit of a tradeoff.
A brief update ..
I have been thoroughly enjoying having my old KA-7100 back in service. It has become a daily driver... I currently have it set up in a small room/office, and am now driving a pair of Paradigm Atom v.3 speakers.
Today, just for fun I borrowed a Carver M-400a power amp, and have the KA-7100 pre-amp driving the Carver. The Atom's seem to enjoy having the extra power on tap.... but I am afraid to really crank it up! I sure can fill the 10x12' room with sound!
Still haven't found the time to finish cleaning up my spare KA-7100 to do some direct A/B comparisons.. I have been spending spare time just listening and enjoying! I hope to get to that this coming week.
Thanks again EW!
By the way... when comparing the preamp section original factory specs for both the KA-7100 and the KA-9100, I was surprised to find that the KA-7100 preamp appears to equal or surpasses the KA-9100 in some respects. The S/N ratios for the TAPE, TUNER, and AUX inputs is 110dB, as opposed to 100dB for the 9100. The freq resp for the TAPE/AUX is 10-100,000Hz (+0, -1.8 dB) on the KA-7100, as opposed to 7-50,000Hz (+0, -1.0 dB) on the KA-9100. Are these differences material in the real world, or insignificant?
EW.. any comments on whether the upgrades/mods would have improved upon any of these specs?
The PHONO stage specs require a bit more interpretation.... the KA-7100 takes a maximum input level of 200mV (rms) with THD 0.02% at 1,000Hz., while the KA-9100 is rated at 250mV (rms) THD 0.03% at 1,000Hz. I don't know what to make of these figures... seems like a teeny bit of a tradeoff.
Seeing as how you're feeding the phono stage perhaps 5mV even with a fairly high output MM cart, the spec is pretty meaningless. Back when phono was King, there used to be some pretty high output carts, but even these didn't put out more than perhaps 10mV (which is huge for a cart). Someone may correct me, but I believe that 10mV was about it for a MM cart (we will not discuss ceramic carts).
The FR specs don't mean too much. Kenwood might have used a filter at the input to purposefully roll off the response on the 9100, and maybe they didn't on the 7100. That won't change with the opamp buffer...in unity gain mode its response is well into the MHz region, however, the rest of the amp is the limiting factor (as well it should be).
Just remember with the 7100 as a preamp...power amplifier on last, off first...that OPA2604 is DC coupled to the output and will misbehave on power up or down, so make sure it gets turned on or off with the separate amplifier in a powered-down state.
The FR specs don't mean too much. Kenwood might have used a filter at the input to purposefully roll off the response on the 9100, and maybe they didn't on the 7100. That won't change with the opamp buffer...in unity gain mode its response is well into the MHz region, however, the rest of the amp is the limiting factor (as well it should be).
Just remember with the 7100 as a preamp...power amplifier on last, off first...that OPA2604 is DC coupled to the output and will misbehave on power up or down, so make sure it gets turned on or off with the separate amplifier in a powered-down state.
Micropassatman
Swollen Member
Anybody swapped out the original binding posts for 5-ways on a vintage Kenwood amp? I really would like to use banana plugs instead of the needle threading technique... Just curious how feasible itmight be.
Micropassatman
Swollen Member
I guess I just find it annoying that I have to be able to 'see' the rear of the unit to wire the speakers up. The 7100/7500 combo are in an armoire in the bedroom, and it is NOT fun trying to remove these pieces while they're wired to the speakers. Guess I'm just splitting hairs now...
an update...
Several weeks ago I noticed that the KA-7100 appeared to be developing a pronounced (and annoying) power-off thump. I consulted with EchoWars, who advised that changing the value of one of the caps (C41) from the original value of 10uf to 2.2uf would cause the protection relay to open almost immediately on power off, and eliminate the thumping!
EW supplied the required cap, and with a little assistance from someone with a steady hand and experience soldering on a PCB (thanks Bolly!) the unit is working like a champ again!
I also took advantage of an opportunity to hook up my KA-7100 in place of Bolly's Yamaha M2, and hear how the Kenwood's power amp section sounds driving Bolly's AR-9's! I have to say I was quite impressed... I found the sound to be very clean and clear in comparison to the Yamaha.
I have no idea how much of this difference to attribute to basic differences in the 2 amps, or to the fact that the Kenwood was recently recapped and overhauled while the Yamaha M2 was original.
The KA-7100 didn't seem to have too much trouble driving the AR-9's to respectable volume levels, but it is worth noting that this was a bi-amped configuration with a Pioneer SPEC-2 driving the bottom end of the AR-9's, using the Pioneer SPEC-1 as the pre-amp. Unfortunately we didn't have a chance to really tinker with relative gain settings of the 2 amps (there is no gain control on the KA-7100) and get the AR-9'S singing to their full potential. I guess that could be the subject of another thread... and maybe another listening session!
Several weeks ago I noticed that the KA-7100 appeared to be developing a pronounced (and annoying) power-off thump. I consulted with EchoWars, who advised that changing the value of one of the caps (C41) from the original value of 10uf to 2.2uf would cause the protection relay to open almost immediately on power off, and eliminate the thumping!
EW supplied the required cap, and with a little assistance from someone with a steady hand and experience soldering on a PCB (thanks Bolly!) the unit is working like a champ again!
I also took advantage of an opportunity to hook up my KA-7100 in place of Bolly's Yamaha M2, and hear how the Kenwood's power amp section sounds driving Bolly's AR-9's! I have to say I was quite impressed... I found the sound to be very clean and clear in comparison to the Yamaha.
I have no idea how much of this difference to attribute to basic differences in the 2 amps, or to the fact that the Kenwood was recently recapped and overhauled while the Yamaha M2 was original.
The KA-7100 didn't seem to have too much trouble driving the AR-9's to respectable volume levels, but it is worth noting that this was a bi-amped configuration with a Pioneer SPEC-2 driving the bottom end of the AR-9's, using the Pioneer SPEC-1 as the pre-amp. Unfortunately we didn't have a chance to really tinker with relative gain settings of the 2 amps (there is no gain control on the KA-7100) and get the AR-9'S singing to their full potential. I guess that could be the subject of another thread... and maybe another listening session!
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hpsenicka said:
Echowars, can you provide any additional technicial details or specs that would help compare the input sensitivity of the modded KA-7100 amp section to the SPEC-2 and/or the Yamaha M-2 we were using?
According to Bolly's info, the input sensitivity specs of those units is:
Yamaha M-2: 1.62V/25k ohm +/- 5k ohm
Pioneer SPEC-2: 2.0V/50k ohm
Honestly, I don't know. Guess I had ample opportunities to test it, with all the 7100's that came through here, but I must admit that I never did. And if I gave you a figure, I'd just be a guess.
Input impedance will be about 30K, but sensitivity...? Certainly it's in the ballpark of 1.2 - 2V. Probably closer to the lower end of that if it's typical of Kenwood gear.
Input impedance will be about 30K, but sensitivity...? Certainly it's in the ballpark of 1.2 - 2V. Probably closer to the lower end of that if it's typical of Kenwood gear.
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